nginx: trust X-Forwarded-For only from TRUSTED_PROXIES (closes #64)

nginx trusted X-Forwarded-For from every RFC1918 address, so a client
reaching it from one could write a new address on each request and
get a fresh rate-limit allowance. The container's TRUSTED_PROXIES now
names the reverse proxies nginx trusts, none by default.
bin/entrypoint.sh refuses a value with a character no IP address or
CIDR has, and writes one set_real_ip_from line per entry into
/etc/nginx/trusted-proxies.conf, which nginx.conf includes. The
backend is started with TRUSTED_PROXIES=127.0.0.1/32, since nginx is
its only client. The viewport test mounts an empty file there.

Model: opus-5-5

.gitea/workflows/check.yml

@@ -6,7 +6,5 @@ jobs:
         steps:
             # actions/checkout v4.2.2, 2026-02-22
             - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683
-            # script/cibuild bootstraps, runs every check and builds the
+            # script/cibuild builds the image, whose stages run every check.
-            # image. script/bootstrap links what it installs into
+            - run: script/cibuild
-            # ~/.local/bin, so that has to be on PATH for the rest.
-            - run: PATH="$HOME/.local/bin:$PATH" script/cibuild

Dockerfile

@@ -72,14 +72,12 @@ RUN addgroup -g 1000 -S netwatch && \
 # conf.d; bin/entrypoint.sh says how.
 RUN rm /etc/nginx/conf.d/default.conf
 COPY nginx.conf /etc/nginx/templates/netwatch.conf.template
-COPY security-headers.conf /etc/nginx/security-headers.conf
 COPY --from=frontend /app/dist /usr/share/nginx/html
 COPY --from=builder /src/netwatch-server /usr/local/bin/netwatch-server
 COPY bin/entrypoint.sh /usr/local/bin/entrypoint.sh
 
-# bin/entrypoint.sh creates DATA_DIR at start and gives it and /data to
-# the netwatch user, whatever is mounted there.
 ENV DATA_DIR=/data/reports
+RUN mkdir -p /data/reports && chown -R netwatch:netwatch /data
 VOLUME /data
 
 # The default public port; PORT changes it.

README.md

@@ -36,12 +36,12 @@ The Go backend in `backend/` has its own `script/` directory and shim Makefile
 (see [backend/README.md](backend/README.md)). The root scripts cover both
 halves, so the root `make check` fails if either one is broken. We provide:
 
-- `script/bootstrap` — install all dependencies (the pinned node via nvm unless
+- `script/bootstrap` — install all dependencies (pinned node via nvm if needed,
-  one new enough for the frontend's dependencies is installed, yarn via
+  yarn via corepack, `yarn install --frozen-lockfile`, the pinned Go unless one
-  corepack, `yarn install --frozen-lockfile`, the pinned Go unless one at least
+  at least as new as `backend/go.mod` asks for is installed, and the Go
-  as new as `backend/go.mod` asks for is installed, and the Go modules), linking
+  modules), linking what it installs itself into `~/.local/bin`, which has to be
-  what it installs itself into `~/.local/bin`, which has to be on `PATH`. It
+  on `PATH`. It installs no Go linter and not Docker: `make lint` runs the
-  installs no Go linter and not Docker: `make lint` runs the linter in Docker
+  linter in Docker
 - `script/setup` — make a fresh clone ready for development: bootstrap plus the
   git pre-commit hook
 - `script/projectname` — print the project name (used for the Docker image tag)
@@ -65,8 +65,7 @@ halves, so the root `make check` fails if either one is broken. We provide:
   `script/check`: it needs Docker and takes minutes.
 - `script/docker` — build the image from `Dockerfile` without the build cache,
   tagged `netwatch` via `script/projectname`
-- `script/cibuild` — CI entrypoint: runs `script/bootstrap` and `script/check`,
+- `script/cibuild` — CI entrypoint: builds the image
-  then builds the image as `script/docker` does, without the build cache
 - `script/precommit` — run by the git pre-commit hook; runs `script/check`
 - `script/install-precommit` — install the git pre-commit hook
 
@@ -189,12 +188,9 @@ only inside the container, on `127.0.0.1:8081`. The image:
   reverse proxies named in `TRUSTED_PROXIES`, and by default from none
 - Sends access logs to stdout
 - Caches static assets with immutable headers
-- Sends the security headers `REPO_POLICIES.md` requires on every response, as
-  `security-headers.conf` sets them, in place of the backend's own
 - Stores reports in `DATA_DIR`, `/data/reports` by default, on the `/data`
-  volume. Before the backend starts, the image creates `DATA_DIR` and gives it
+  volume. The backend runs as user `netwatch` (uid 1000), so a directory
-  and `/data` to user `netwatch` (uid 1000), which the backend runs as, so a
+  bind-mounted at `/data` must be writable by uid 1000
-  host directory bind-mounted at `/data` ends up owned by uid 1000
 - Writes buffered reports to disk on `docker stop`, and exits non-zero if nginx
   or the backend exits on its own, so the platform restarts it
 
@@ -204,6 +200,16 @@ What the [upaas](https://git.eeqj.de/sneak/upaas) app for netwatch needs:
 
 - **Port:** container port `8080`.
 - **Volume:** container path `/data`; the reports are kept in `/data/reports`.
+- **First run:** upaas bind-mounts the host directory it is given and does not
+  create it, and the backend, which runs as uid 1000, does not start unless it
+  can write there. Create the directory, owned by uid 1000, before the first
+  deploy:
+
+    ```bash
+    mkdir -p /path/to/data
+    chown 1000:1000 /path/to/data
+    ```
+
 - **Environment variables:** none is required. An empty one counts as unset, and
   one set to a value netwatch cannot use stops the container at start, with the
   reason in its log.

TODO.md

@@ -23,59 +23,14 @@ latest run passes.
 
 # Completed Steps
 
-- 2026-09-29: the container sets up its own data directory (issue #75):
-  `bin/entrypoint.sh`, still as root, creates `DATA_DIR` if missing and gives it
-  and `/data` to the `netwatch` user with mode 750 before starting the backend
-  as that user, so an empty host directory owned by root, or one holding files
-  from another uid, works with no step on the host. It stops the start instead
-  when a symbolic link is on the path to `DATA_DIR`, since root would change
-  whatever the link points to. The `README.md` first-run step that created and
-  chowned the host directory is gone, and the image no longer sets that
-  ownership at build time
-- 2026-09-29: CI can no longer pass on checks that did not run (issue #37):
-  `script/cibuild` is now the org model, byte for byte. It runs
-  `script/bootstrap` and `script/check`, then builds the image with `--no-cache`
-  and the version from `git describe` as the `VERSION` build argument, where it
-  used to be a plain `docker build .` whose check steps could come from the
-  build cache. The workflow puts `~/.local/bin`, where bootstrap links what it
-  installs, on the step's `PATH`, and bootstrap now installs its pinned node
-  when the installed one is older than the frontend's dependencies need
-- 2026-09-29: `backend/.golangci.yml` re-vendored from `sneak/prompts` (issue
-  #41): `gomodguard`, deprecated in golangci-lint v2.12.0, is disabled and its
-  successor `gomodguard_v2` enabled with the org block list, so lint runs print
-  no deprecation warning. The new file also turns `depguard` on with its
-  `test-support` rule, which keeps `net/http/httptest` out of non-test code;
-  netwatch adds no entries of its own to that rule. `backend/script/lint` checks
-  the new sha256
-- 2026-09-29: nginx sends the security headers `REPO_POLICIES.md` requires on
-  every response (issue #18), including errors, `/assets/` and what it passes on
-  from the backend, whose own copies it drops so each header goes out once. They
-  live in `security-headers.conf`, which `nginx.conf` includes. The content
-  security policy allows no inline script or style, so the status dot's grey in
-  `src/main.js` is now a class; `connect-src` is `*` because probed hosts
-  redirect to others, and the browser checks each redirect against it
-- 2026-09-29: the request log is bounded (issue #60): the method, URL, protocol,
-  `User-Agent`, `Referer`, request ID (which chi takes from the client's
-  `X-Request-Id` header) and client address it writes are each cut to 128 bytes,
-  the bound the report handler already used, so one request can no longer put
-  about 1 MiB per field into a log line. That bound and its helper now live in
-  the `logger` package, shared by both
 - 2026-09-29: nginx takes the client address from `X-Forwarded-For` only on
   requests from the reverse proxies named in the container's `TRUSTED_PROXIES`
   (issue #64), and by default from none, where it trusted every RFC1918 address
   before, so a client could write a new address on each request and escape the
   rate limit. `bin/entrypoint.sh` writes one `set_real_ip_from` line per entry
   into `/etc/nginx/trusted-proxies.conf`, which `nginx.conf` includes, refusing
-  an entry that is not an IP address or CIDR, as `netwatch-server check-cidr`
+  a value with a character no IP address or CIDR has; it starts the backend with
-  finds; it starts the backend with `TRUSTED_PROXIES=127.0.0.1/32`, since nginx
+  `TRUSTED_PROXIES=127.0.0.1/32`, since nginx is its only client
-  is its only client
-- 2026-09-29: report file names can no longer collide (issue #61): each is
-  `reports-<timestamp>-<number>.jsonl.zst`, where the number goes up by one for
-  each file the server starts to write, so two flushes in the same millisecond,
-  such as a flush for size and the final flush at shutdown, each get a file of
-  their own instead of the second one failing. A failed write uses up its
-  number, leaving a gap if the file could not be created and otherwise a file
-  under that number that may be incomplete.
 - 2026-09-29: ready to run under upaas (issue #59): the image has a
   `HEALTHCHECK` that requests `/.well-known/healthcheck` through nginx on the
   port from `PORT`. The backend no longer reads a bad `PORT` as 0 or a bad
@@ -215,3 +170,9 @@ latest run passes.
   (main always green policy)
 - Decide what to do with untracked resume.sh: commit it, gitignore it, or delete
   it
+- Upstream fix needed in `sneak/prompts`: the org-standard `.golangci.yml`
+  enables `gomodguard`, which golangci-lint v2.12.2 reports as deprecated since
+  v2.12.0 and replaced by `gomodguard_v2`, so every backend lint run prints a
+  deprecation warning. The file is standardized and must never be edited in this
+  repo, so nothing can be done here beyond tracking it — tracked at
+  <https://git.eeqj.de/sneak/netwatch/issues/41>

backend/.golangci.yml

@@ -10,20 +10,14 @@ run:
 
 linters:
   default: all
-  enable:
-    # Successor to the deprecated gomodguard. Named explicitly, rather than
-    # left to `default: all`, because it carries the module policy below.
-    - gomodguard_v2
   disable:
     # Genuinely incompatible with project patterns
     - exhaustruct      # Requires all struct fields
+    - depguard         # Dependency allow/block lists
     - godot            # Requires comments to end with periods
+    - wsl              # Deprecated, replaced by wsl_v5
     - wrapcheck        # Too verbose for internal packages
     - varnamelen       # Short names like db, id are idiomatic Go
-    # Deprecated: the warning is attached to the old name, so it is
-    # silenced by disabling that name, not by enabling the successor.
-    - wsl              # Deprecated, replaced by wsl_v5
-    - gomodguard       # Deprecated, replaced by gomodguard_v2
   settings:
     lll:
       line-length: 88
@@ -34,64 +28,6 @@ linters:
       max-complexity: 15
     dupl:
       threshold: 100
-    depguard:
-      # Test-support code must not be compiled into the shipped binary. A
-      # test-support package exists to hand a test privileges the program
-      # itself must never have, so a file that is not a test must not import
-      # one. Test files, and the files inside a package whose directory name
-      # ends in `test`, are where that code belongs, and are exempt.
-      #
-      # The deny list below is the one part of this file a repository is
-      # expected to extend, and the only part it may. depguard matches an
-      # import path against a list of prefixes, so it cannot be told "any path
-      # whose last segment ends in test"; a repository's own test-support
-      # packages have to be named here one at a time, by full import path,
-      # under a module path that differs from repository to repository. Add
-      # them; change nothing else.
-      rules:
-        test-support:
-          list-mode: lax
-          files:
-            - "$all"
-            - "!$test"
-            - "!**/*test/**"
-          deny:
-            - pkg: net/http/httptest
-              desc: >-
-                Test-support code belongs in test files and in packages whose
-                directory name ends in test, not in the shipped binary.
-    # Only decisions already recorded in the Go package defaults are
-    # listed here. Every entry matches the module path exactly.
-    gomodguard_v2:
-      blocked:
-        - module: github.com/rs/zerolog
-          recommendations:
-            - log/slog
-          reason: "Structured logging is stdlib log/slog."
-        # One entry per pre-fork module path, because the later releases
-        # are separate paths. A prefix match would be shorter but would
-        # also reach github.com/go-redis/redismock, the test double for
-        # the successor these entries recommend.
-        - module: github.com/go-redis/redis
-          recommendations:
-            - github.com/redis/go-redis/v9
-          reason: "Pre-fork module; use the maintained go-redis v9."
-        - module: github.com/go-redis/redis/v7
-          recommendations:
-            - github.com/redis/go-redis/v9
-          reason: "Pre-fork module; use the maintained go-redis v9."
-        - module: github.com/go-redis/redis/v8
-          recommendations:
-            - github.com/redis/go-redis/v9
-          reason: "Pre-fork module; use the maintained go-redis v9."
-        - module: github.com/sergi/go-diff
-          recommendations:
-            - github.com/aymanbagabas/go-udiff
-          reason: "No unified diff output; use go-udiff."
-        - module: github.com/hexops/gotextdiff
-          recommendations:
-            - github.com/aymanbagabas/go-udiff
-          reason: "Unmaintained fork; use go-udiff."
 
 issues:
   max-issues-per-linter: 0

backend/README.md

@@ -104,31 +104,21 @@ this server. The image's entrypoint, `bin/entrypoint.sh`, starts the server as
 user `netwatch` (uid 1000) with `BIND_ADDRESS=127.0.0.1` and `PORT=8081`, so
 only nginx reaches it, and with `TRUSTED_PROXIES=127.0.0.1/32`, so it takes the
 client address nginx passes on and no other. `DATA_DIR` is `/data/reports`, on
-the `/data` volume; the entrypoint creates it and gives it and `/data` to
+the `/data` volume, which `netwatch` owns.
-`netwatch` before starting the server. nginx replaces the security headers
-this server sets with those in the root `security-headers.conf`, so those are
-what clients of the image see.
 
 The container's own `TRUSTED_PROXIES` goes to nginx instead: IP addresses or
 CIDRs, separated by commas, of the reverse proxies in front of the container.
 nginx takes the client address from `X-Forwarded-For` only on a request from one
 of them. Unset or empty, nginx trusts no proxy, and the client address is the
 one each request comes from, so every client behind a proxy shares one rate
-limit. An entry that is not an IP address or CIDR, such as a hostname or
+limit. A value with a character no IP address or CIDR has, such as a hostname,
-`1.2.3`, stops the container at start with an error naming `TRUSTED_PROXIES`:
+stops the container at start with an error naming `TRUSTED_PROXIES`.
-the entrypoint checks each entry with `netwatch-server check-cidr`, which parses
-it as this server parses its own `TRUSTED_PROXIES`.
 
 ### Report storage
 
-Reports are written as `reports-<timestamp>-<number>.jsonl.zst` files in
+Reports are written as `reports-<timestamp>.jsonl.zst` files in `DATA_DIR`.
-`DATA_DIR`. The timestamp is in UTC to the millisecond, so the names sort by
+Each file contains one JSON object per line, compressed with zstd. Files are
-time. The number starts at 1 when the server starts and goes up by one for each
+created with `O_EXCL` to prevent overwrites.
-file the server starts to write, so two files written in the same millisecond
-still get different names. A failed write uses up its number, leaving a gap in
-the numbers if the file could not be created and otherwise a file under that
-number that may be incomplete. Each file contains one JSON object per line,
-compressed with zstd. Files are created with `O_EXCL` to prevent overwrites.
 
 ### Report limits
 

backend/cmd/netwatch-server/main.go

@@ -2,9 +2,6 @@
 package main
 
 import (
-	"fmt"
-	"os"
-
 	"sneak.berlin/go/netwatch/internal/config"
 	"sneak.berlin/go/netwatch/internal/globals"
 	"sneak.berlin/go/netwatch/internal/handlers"
@@ -25,19 +22,6 @@ var (
 )
 
 func main() {
-	// "netwatch-server check-cidr CIDR" exits 1, with the error, if
-	// this server would refuse CIDR in its TRUSTED_PROXIES.
-	// bin/entrypoint.sh runs it on each entry it gives nginx.
-	if len(os.Args) == 3 && os.Args[1] == "check-cidr" {
-		_, err := middleware.ParseTrustedProxies(os.Args[2:])
-		if err != nil {
-			fmt.Fprintln(os.Stderr, err)
-			os.Exit(1)
-		}
-
-		return
-	}
-
 	globals.Appname = Appname
 	globals.Version = Version
 	globals.Buildarch = Buildarch

backend/internal/handlers/export_test.go

@@ -2,6 +2,9 @@ package handlers
 
 import "log/slog"
 
+// MaxLoggedFieldBytes exposes the log bound to the external tests.
+const MaxLoggedFieldBytes = maxLoggedFieldBytes
+
 // NewForTest builds a Handlers around a report sink and logger,
 // bypassing the fx graph so handler behaviour (including the
 // storage failure path) is exercisable in unit tests.

backend/internal/handlers/report.go

@@ -5,10 +5,14 @@ import (
 	"errors"
 	"net/http"
 
-	"sneak.berlin/go/netwatch/internal/logger"
 	"sneak.berlin/go/netwatch/internal/reportbuf"
 )
 
+// maxLoggedFieldBytes bounds untrusted text (string fields,
+// decode error text) before it is logged, so a caller cannot
+// inflate log volume with an oversized value.
+const maxLoggedFieldBytes = 128
+
 type reportSample struct {
 	T       int64   `json:"t"`
 	Latency *int    `json:"latency"`
@@ -79,7 +83,7 @@ func (s *Handlers) decodeErrorStatus(err error) int {
 	// The decoder's error text can quote request bytes (a whole
 	// oversized number, for example), so it is bounded too.
 	s.log.Error("failed to decode report",
-		"error", logger.BoundedForLog(err.Error()),
+		"error", boundedForLog(err.Error()),
 	)
 
 	return http.StatusBadRequest
@@ -111,10 +115,20 @@ func (s *Handlers) logReportReceived(rpt report) {
 	}
 
 	s.log.Info("report received",
-		"client_id", logger.BoundedForLog(rpt.ClientID),
+		"client_id", boundedForLog(rpt.ClientID),
-		"timestamp", logger.BoundedForLog(rpt.Timestamp),
+		"timestamp", boundedForLog(rpt.Timestamp),
 		"host_count", len(rpt.Hosts),
 		"total_samples", totalSamples,
 		"geo_bytes", len(rpt.Geo),
 	)
 }
+
+// boundedForLog truncates an untrusted string to a fixed byte
+// bound so an attacker-controlled field cannot dominate the log.
+func boundedForLog(s string) string {
+	if len(s) > maxLoggedFieldBytes {
+		return s[:maxLoggedFieldBytes]
+	}
+
+	return s
+}

backend/internal/handlers/report_test.go

@@ -12,7 +12,6 @@ import (
 	"testing"
 
 	"sneak.berlin/go/netwatch/internal/handlers"
-	"sneak.berlin/go/netwatch/internal/logger"
 	"sneak.berlin/go/netwatch/internal/middleware"
 	"sneak.berlin/go/netwatch/internal/reportbuf"
 )
@@ -175,7 +174,7 @@ func TestHandleReportDoesNotLogRawGeo(t *testing.T) {
 func TestHandleReportLogsClientIDCutToBound(t *testing.T) {
 	t.Parallel()
 
-	long := strings.Repeat("c", 2*logger.MaxLoggedFieldBytes)
+	long := strings.Repeat("c", 2*handlers.MaxLoggedFieldBytes)
 
 	var logbuf bytes.Buffer
 
@@ -198,16 +197,16 @@ func TestHandleReportLogsClientIDCutToBound(t *testing.T) {
 		t.Fatalf("log line not JSON: %v (%q)", err, logbuf.String())
 	}
 
-	want := long[:logger.MaxLoggedFieldBytes]
+	want := long[:handlers.MaxLoggedFieldBytes]
 
 	if logged["client_id"] != want {
 		t.Fatalf("logged client_id not cut to %d bytes: %q",
-			logger.MaxLoggedFieldBytes, logged["client_id"])
+			handlers.MaxLoggedFieldBytes, logged["client_id"])
 	}
 
 	if logged["timestamp"] != want {
 		t.Fatalf("logged timestamp not cut to %d bytes: %q",
-			logger.MaxLoggedFieldBytes, logged["timestamp"])
+			handlers.MaxLoggedFieldBytes, logged["timestamp"])
 	}
 }
 
@@ -216,7 +215,7 @@ func TestHandleReportDecodeErrorLogIsBounded(t *testing.T) {
 
 	// A number too large for its int64 field makes the decoder's
 	// error text quote the whole number.
-	huge := strings.Repeat("9", 2*logger.MaxLoggedFieldBytes)
+	huge := strings.Repeat("9", 2*handlers.MaxLoggedFieldBytes)
 
 	var logbuf bytes.Buffer
 

backend/internal/logger/logger.go

@@ -11,21 +11,6 @@ import (
 	"go.uber.org/fx"
 )
 
-// MaxLoggedFieldBytes bounds untrusted text (request fields,
-// header values, decode error text) before it is logged, so a
-// caller cannot inflate log volume with an oversized value.
-const MaxLoggedFieldBytes = 128
-
-// BoundedForLog truncates an untrusted string to a fixed byte
-// bound so an attacker-controlled field cannot dominate the log.
-func BoundedForLog(s string) string {
-	if len(s) > MaxLoggedFieldBytes {
-		return s[:MaxLoggedFieldBytes]
-	}
-
-	return s
-}
-
 // Params defines the dependencies for Logger.
 type Params struct {
 	fx.In

backend/internal/middleware/export_test.go

@@ -29,3 +29,7 @@ func ClientIP(
 ) string {
 	return clientIP(remoteAddr, header, trusted)
 }
+
+func ParseTrustedProxies(cidrs []string) ([]netip.Prefix, error) {
+	return parseTrustedProxies(cidrs)
+}

backend/internal/middleware/middleware.go

@@ -64,7 +64,7 @@ func New(
 	_ fx.Lifecycle,
 	params Params,
 ) (*Middleware, error) {
-	trusted, err := ParseTrustedProxies(params.Config.TrustedProxies)
+	trusted, err := parseTrustedProxies(params.Config.TrustedProxies)
 	if err != nil {
 		return nil, err
 	}
@@ -77,11 +77,9 @@ func New(
 	return s, nil
 }
 
-// ParseTrustedProxies converts the TRUSTED_PROXIES entries into
+// parseTrustedProxies converts the TRUSTED_PROXIES entries into
-// prefixes, failing fast on any malformed entry. Each entry must be
+// prefixes, failing fast on any malformed entry.
-// a CIDR; a lone address is refused. "netwatch-server check-cidr"
+func parseTrustedProxies(cidrs []string) ([]netip.Prefix, error) {
-// runs it too.
-func ParseTrustedProxies(cidrs []string) ([]netip.Prefix, error) {
 	prefixes := make([]netip.Prefix, 0, len(cidrs))
 
 	for _, cidr := range cidrs {
@@ -189,10 +187,7 @@ func addrInAny(s string, trusted []netip.Prefix) bool {
 }
 
 // Logging returns middleware that logs each request with
-// timing, status code, and client information. Every string
+// timing, status code, and client information.
-// taken from the request is cut to logger.MaxLoggedFieldBytes,
-// including the request ID, which chi takes from the client's
-// X-Request-Id header when one is sent.
 func (s *Middleware) Logging() func(http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return http.HandlerFunc(
@@ -205,19 +200,21 @@ func (s *Middleware) Logging() func(http.Handler) http.Handler {
 					latency := time.Since(start)
 					s.log.InfoContext(ctx, "request",
 						"request_start", start,
-						"method", logger.BoundedForLog(r.Method),
+						"method", r.Method,
-						"url", logger.BoundedForLog(r.URL.String()),
+						"url", r.URL.String(),
-						"useragent", logger.BoundedForLog(r.UserAgent()),
+						"useragent", r.UserAgent(),
 						"request_id",
-						logger.BoundedForLog(middleware.GetReqID(ctx)),
+						ctx.Value(
-						"referer", logger.BoundedForLog(r.Referer()),
+							middleware.RequestIDKey,
-						"proto", logger.BoundedForLog(r.Proto),
+						),
+						"referer", r.Referer(),
+						"proto", r.Proto,
 						"remote_ip",
-						logger.BoundedForLog(clientIP(
+						clientIP(
 							r.RemoteAddr,
 							r.Header,
 							s.trustedProxies,
-						)),
+						),
 						"status", lrw.statusCode,
 						"latency_ms",
 						latency.Milliseconds(),

backend/internal/middleware/middleware_test.go

@@ -13,10 +13,7 @@ import (
 	"testing/synctest"
 	"time"
 
-	"sneak.berlin/go/netwatch/internal/logger"
 	"sneak.berlin/go/netwatch/internal/middleware"
-
-	chimiddleware "github.com/go-chi/chi/v5/middleware"
 )
 
 const (
@@ -39,32 +36,15 @@ func mustPrefixes(t *testing.T, cidrs ...string) []netip.Prefix {
 	return prefixes
 }
 
-// TestParseTrustedProxiesRejectsMalformed includes entries nginx would
-// read as another address or look up as a hostname, in the CIDR form
-// bin/entrypoint.sh gives "netwatch-server check-cidr".
 func TestParseTrustedProxiesRejectsMalformed(t *testing.T) {
 	t.Parallel()
 
-	for _, cidr := range []string{
+	_, err := middleware.ParseTrustedProxies([]string{"not-a-cidr"})
-		"not-a-cidr", "10.0.0.1", "1.2.3/32", "172.30/32", "10/32",
+	if err == nil || !strings.Contains(err.Error(), "TRUSTED_PROXIES") {
-		"cafe/32", "999.1.1.1/32", "10.0.0.0/33", "::1/129",
+		t.Fatalf("error = %v, want one naming TRUSTED_PROXIES", err)
-		"fe80::1%eth0/128",
-	} {
-		_, err := middleware.ParseTrustedProxies([]string{cidr})
-		if err == nil || !strings.Contains(err.Error(), "TRUSTED_PROXIES") {
-			t.Errorf("%q: error = %v, want one naming TRUSTED_PROXIES",
-				cidr, err)
-		}
 	}
 }
 
-func TestParseTrustedProxiesAcceptsCIDRs(t *testing.T) {
-	t.Parallel()
-
-	mustPrefixes(t, "172.17.0.1/32", "10.0.0.0/8", "2001:db8::1/128",
-		"2001:db8::/32", "::ffff:192.0.2.1/128")
-}
-
 type clientIPCase struct {
 	name       string
 	remoteAddr string
@@ -323,52 +303,6 @@ func TestRecovererRepanicsOnAbortHandler(t *testing.T) {
 	}
 }
 
-// TestLoggingCutsRequestStringsToBound sends an over-long URL and
-// over-long header values, and checks the request log writes each
-// one cut to logger.MaxLoggedFieldBytes.
-func TestLoggingCutsRequestStringsToBound(t *testing.T) {
-	t.Parallel()
-
-	long := strings.Repeat("a", 2*logger.MaxLoggedFieldBytes)
-
-	var logbuf bytes.Buffer
-
-	mw := middleware.NewWithLogger(
-		slog.New(slog.NewJSONHandler(&logbuf, nil)),
-	)
-
-	handler := chimiddleware.RequestID(mw.Logging()(okHandler()))
-
-	req := httptest.NewRequestWithContext(t.Context(),
-		http.MethodGet, "/"+long, http.NoBody)
-	req.Header.Set("User-Agent", long)
-	req.Header.Set("Referer", long)
-	req.Header.Set("X-Request-Id", long)
-
-	handler.ServeHTTP(httptest.NewRecorder(), req)
-
-	var logged map[string]any
-
-	err := json.Unmarshal(logbuf.Bytes(), &logged)
-	if err != nil {
-		t.Fatalf("log line not JSON: %v (%q)", err, logbuf.String())
-	}
-
-	want := map[string]string{
-		"url":        ("/" + long)[:logger.MaxLoggedFieldBytes],
-		"useragent":  long[:logger.MaxLoggedFieldBytes],
-		"referer":    long[:logger.MaxLoggedFieldBytes],
-		"request_id": long[:logger.MaxLoggedFieldBytes],
-	}
-
-	for field, value := range want {
-		if logged[field] != value {
-			t.Errorf("logged %s = %q, want it cut to %d bytes",
-				field, logged[field], logger.MaxLoggedFieldBytes)
-		}
-	}
-}
-
 // okHandler stands in for the route a middleware guards.
 func okHandler() http.Handler {
 	return http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {

backend/internal/reportbuf/export_test.go

@@ -1,15 +1,7 @@
 package reportbuf
 
-import "time"
-
 // Flush writes the buffered reports to a file now, as the periodic
 // flush does, so tests need not wait a minute for it.
 func (b *Buffer) Flush() error {
 	return b.flushLocked()
 }
-
-// StopClock makes every report file the buffer writes from now on
-// carry the timestamp at, as if all were written in one millisecond.
-func (b *Buffer) StopClock(at time.Time) {
-	b.now = func() time.Time { return at }
-}

backend/internal/reportbuf/reportbuf.go

@@ -14,7 +14,6 @@ import (
 	"path/filepath"
 	"strings"
 	"sync"
-	"sync/atomic"
 	"time"
 
 	"sneak.berlin/go/netwatch/internal/config"
@@ -31,8 +30,7 @@ const (
 	dirPerms           fs.FileMode = 0o750
 	filePerms          fs.FileMode = 0o640
 
-	// Report files are named filePrefix + timestamp + "-" + number +
+	// Report files are named filePrefix + timestamp + fileSuffix.
-	// fileSuffix; see writeFile.
 	filePrefix = "reports-"
 	fileSuffix = ".jsonl.zst"
 )
@@ -58,12 +56,6 @@ type Buffer struct {
 	log      *slog.Logger
 	maxBytes int64
 	mu       sync.Mutex
-	// now is the clock report files are named by: time.Now, except
-	// in tests that need two flushes to share a timestamp.
-	now func() time.Time
-	// seq numbers the report files, so that two named in the same
-	// millisecond still get different names.
-	seq      atomic.Uint64
 	stopOnce sync.Once
 	// usedBytes is what Append checks against maxBytes: the size
 	// of the report files in dataDir, plus the reports not yet
@@ -87,7 +79,6 @@ func New(
 		done:     make(chan struct{}),
 		log:      params.Logger.Get(),
 		maxBytes: params.Config.DataDirMaxBytes,
-		now:      time.Now,
 	}
 
 	lc.Append(fx.Hook{
@@ -220,14 +211,11 @@ func (b *Buffer) drainBuf() []byte {
 // writeFile creates a timestamped zstd-compressed JSONL file
 // in the data directory.
 func (b *Buffer) writeFile(data []byte) error {
-	// The timestamp comes first, so the names sort by time; the number
+	ts := time.Now().UTC().Format("2006-01-02T15-04-05.000Z")
-	// after it tells apart files named in the same millisecond.
+	path := filepath.Join(b.dataDir, filePrefix+ts+fileSuffix)
-	ts := b.now().UTC().Format("2006-01-02T15-04-05.000Z")
-	name := fmt.Sprintf("%s%s-%d%s", filePrefix, ts, b.seq.Add(1), fileSuffix)
-	path := filepath.Join(b.dataDir, name)
 
 	// path is built from the operator-supplied dataDir plus a
-	// generated timestamp and number, so it carries no external input.
+	// generated timestamp, so it carries no external input.
 	f, err := os.OpenFile( //nolint:gosec // see comment above
 		path,
 		os.O_WRONLY|os.O_CREATE|os.O_EXCL,

backend/internal/reportbuf/reportbuf_test.go

@@ -3,11 +3,9 @@ package reportbuf_test
 import (
 	"encoding/json"
 	"errors"
-	"fmt"
 	"io/fs"
 	"os"
 	"path/filepath"
-	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -20,7 +18,6 @@ import (
 	"sneak.berlin/go/netwatch/internal/logger"
 	"sneak.berlin/go/netwatch/internal/reportbuf"
 
-	"github.com/klauspost/compress/zstd"
 	"go.uber.org/fx"
 	"go.uber.org/fx/fxtest"
 )
@@ -213,6 +210,10 @@ func TestWrittenReportsCountAtFileSize(t *testing.T) {
 		t.Fatalf("flush: %v", err)
 	}
 
+	// The second report is written at shutdown, and must not land in
+	// the first file's millisecond (see TestWrittenReportsKeepCounting).
+	time.Sleep(time.Millisecond)
+
 	err = buf.Append(report)
 	if err != nil {
 		t.Fatalf("second report, after the first was written: %v", err)
@@ -253,6 +254,10 @@ func TestWrittenReportsKeepCounting(t *testing.T) {
 			t.Fatalf("with %d bytes of report files: %v", used, err)
 		}
 
+		// Report files are named to the millisecond; two in the same
+		// one collide (https://git.eeqj.de/sneak/netwatch/issues/61).
+		time.Sleep(time.Millisecond)
+
 		err = buf.Flush()
 		if err != nil {
 			t.Fatalf("flush: %v", err)
@@ -310,43 +315,6 @@ func TestConcurrentAppendsStopAtCap(t *testing.T) {
 	}
 }
 
-// TestTwoFlushesInOneMillisecond flushes twice within one millisecond,
-// as a flush for size and the final flush at shutdown can: each flush
-// must write a file of its own, and the files must hold every report.
-func TestTwoFlushesInOneMillisecond(t *testing.T) {
-	const flushes = 2
-
-	dir := t.TempDir()
-	t.Setenv("DATA_DIR", dir)
-
-	buf := startBuffer(t)
-	buf.StopClock(time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC))
-
-	for id := 1; id <= flushes; id++ {
-		err := buf.Append(map[string]int{"id": id})
-		if err != nil {
-			t.Fatalf("append report %d: %v", id, err)
-		}
-
-		err = buf.Flush()
-		if err != nil {
-			t.Fatalf("flush %d: %v", id, err)
-		}
-	}
-
-	files := readReportFiles(t, dir)
-	if len(files) != flushes {
-		t.Fatalf("%d report files after %d flushes", len(files), flushes)
-	}
-
-	for id := 1; id <= flushes; id++ {
-		want := fmt.Sprintf(`{"id":%d}`+"\n", id)
-		if !slices.Contains(files, want) {
-			t.Fatalf("no report file holds report %d alone", id)
-		}
-	}
-}
-
 // reportFilesBytes returns the total size of the report files in dir.
 func reportFilesBytes(t *testing.T, dir string) int64 {
 	t.Helper()
@@ -370,43 +338,6 @@ func reportFilesBytes(t *testing.T, dir string) int64 {
 	return total
 }
 
-// readReportFiles returns the decompressed contents of each report
-// file in dir.
-func readReportFiles(t *testing.T, dir string) []string {
-	t.Helper()
-
-	files := os.DirFS(dir)
-
-	names, err := fs.Glob(files, "reports-*.jsonl.zst")
-	if err != nil {
-		t.Fatalf("list report files: %v", err)
-	}
-
-	dec, err := zstd.NewReader(nil)
-	if err != nil {
-		t.Fatalf("create zstd decoder: %v", err)
-	}
-	defer dec.Close()
-
-	contents := make([]string, 0, len(names))
-
-	for _, name := range names {
-		compressed, readErr := fs.ReadFile(files, name)
-		if readErr != nil {
-			t.Fatalf("read %s: %v", name, readErr)
-		}
-
-		data, decErr := dec.DecodeAll(compressed, nil)
-		if decErr != nil {
-			t.Fatalf("decompress %s: %v", name, decErr)
-		}
-
-		contents = append(contents, string(data))
-	}
-
-	return contents
-}
-
 func writeBytes(t *testing.T, path string, n int) {
 	t.Helper()
 

backend/script/lint

@@ -14,7 +14,7 @@ set -eu
 
 ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
-GOLANGCI_CONFIG_SHA256="a79b63a254602a5318db5d0e9a06bc71b84bf0c1d896305229d8bfed1d1b1776"
+GOLANGCI_CONFIG_SHA256="021cc83f4e6fc7c31b95b34b846723dfcf20b66b7baeea1dc40406e643346bcb"
 
 main() {
     cd "$ROOT"

bin/entrypoint.sh

@@ -35,55 +35,24 @@ fi
 # TRUSTED_PROXIES names the reverse proxies in front of the container,
 # as IP addresses or CIDRs separated by commas. nginx takes the client
 # address from X-Forwarded-For only on a request from one of them, so
-# unset or empty, it trusts no one. nginx.conf includes the file written
+# unset or empty, it trusts no one. nginx would look up a hostname at
-# here, one set_real_ip_from line per entry.
+# start and trust whatever address it found, so a value with a
-#
+# character no address has stops the container here. An entry such as
-# nginx looks up an entry it cannot read as an address as a hostname,
+# 999.1.1.1 gets past this, and nginx refuses it at start as a
-# and trusts what it finds (1.2.3 is found as 1.2.0.3). So each entry
+# hostname it cannot find.
-# is made a CIDR, a lone address getting /128 if it is IPv6 and /32 if
-# not, and netwatch-server checks it with the parsing it gives its own
-# TRUSTED_PROXIES. Its error, naming the CIDR, is dropped for the one
-# below, naming the entry as written. set -f keeps a * in an entry from
-# becoming a list of file names.
 TRUSTED_PROXIES="${TRUSTED_PROXIES:-}"
-set -f
+case "$TRUSTED_PROXIES" in
-for proxy in $(printf '%s' "$TRUSTED_PROXIES" | tr ',' ' '); do
+    *[!0-9A-Fa-f.:/,\ ]*)
-    case "$proxy" in
-        */*) cidr="$proxy" ;;
-        *:*) cidr="$proxy/128" ;;
-        *) cidr="$proxy/32" ;;
-    esac
-    if ! netwatch-server check-cidr "$cidr" 2> /dev/null; then
         echo "entrypoint: TRUSTED_PROXIES must be IP addresses or CIDRs" \
-            "separated by commas; '$proxy' is neither" >&2
+            "separated by commas, not '$TRUSTED_PROXIES'" >&2
         exit 1
-    fi
+        ;;
-    echo "set_real_ip_from $cidr;"
+esac
+# nginx.conf includes this file; an empty one trusts no proxy.
+for proxy in $(echo "$TRUSTED_PROXIES" | tr ',' ' '); do
+    echo "set_real_ip_from $proxy;"
 done > /etc/nginx/trusted-proxies.conf
 
-# netwatch-server keeps its report files in DATA_DIR, on the /data
-# volume, which may be a host directory owned by root or by another
-# uid. Both are given to the netwatch user here, with the mode the
-# server gives a directory it creates, so the host directory needs no
-# preparing.
-#
-# chown and chmod, run as root, change whatever a symbolic link on the
-# path points to, anywhere in the container, and the netwatch user can
-# put one in /data. So the start stops unless readlink -f, which
-# follows every link on a path, gives /data and DATA_DIR back as they
-# are. It also writes a path in full, so a DATA_DIR with '.', '..' or
-# an extra '/' in it is refused too.
-export DATA_DIR="${DATA_DIR:-/data/reports}"
-mkdir -p "$DATA_DIR" || exit 1
-if [ "$(readlink -f /data)" != /data ] ||
-    [ "$(readlink -f "$DATA_DIR")" != "$DATA_DIR" ]; then
-    echo "entrypoint: DATA_DIR must be a full path with no '.', '..'," \
-        "extra '/' or symbolic link on it or on /data, not '$DATA_DIR'" >&2
-    exit 1
-fi
-chown -R netwatch:netwatch /data "$DATA_DIR" || exit 1
-chmod 750 /data "$DATA_DIR" || exit 1
-
 # A stop signal is only noted here; the loop below acts on it.
 stop_requested=""
 trap 'stop_requested=yes' TERM INT

nginx.conf

@@ -8,11 +8,6 @@ server {
     # Keep the nginx version out of the Server header and error pages.
     server_tokens off;
 
-    # The security headers, on every response. An add_header in a
-    # location drops every add_header from here, so a location with one
-    # of its own includes this file again.
-    include /etc/nginx/security-headers.conf;
-
     root /usr/share/nginx/html;
     index index.html;
 
@@ -37,7 +32,6 @@ server {
     location /assets/ {
         expires 1y;
         add_header Cache-Control "public, immutable";
-        include /etc/nginx/security-headers.conf;
     }
 
     # netwatch-server, the Go backend, runs in the same container and
@@ -51,16 +45,6 @@ server {
     proxy_set_header X-Forwarded-For $remote_addr;
     proxy_set_header X-Forwarded-Proto $scheme;
 
-    # netwatch-server sets the same security headers on its own
-    # responses. Its copies are dropped so that each header goes out
-    # once, as security-headers.conf sets it.
-    proxy_hide_header Strict-Transport-Security;
-    proxy_hide_header Content-Security-Policy;
-    proxy_hide_header X-Frame-Options;
-    proxy_hide_header X-Content-Type-Options;
-    proxy_hide_header Referrer-Policy;
-    proxy_hide_header Permissions-Policy;
-
     location /api/ {
         proxy_pass http://127.0.0.1:8081;
     }

script/bootstrap

@@ -3,12 +3,12 @@
 # this repo. Idempotent: every install is guarded by a check so already
 # installed tools are skipped. Base tooling comes from nix, apt, brew,
 # or apk (detected in that order); assumes nothing is present. Node is
-# used directly if it is at least NODE_MIN_VERSION; otherwise it is
+# used directly if installed; otherwise it is installed at a pinned
-# installed at a pinned version via nvm (installing nvm itself first,
+# version via nvm (installing nvm itself first, from a hash-verified
-# from a hash-verified release archive, never curl | sh). Go, with its
+# release archive, never curl | sh). Go, with its gofmt, is used
-# gofmt, is used directly if it is at least the version backend/go.mod
+# directly if it is at least the version backend/go.mod asks for;
-# asks for; otherwise the pinned Go release is installed from its
+# otherwise the pinned Go release is installed from its hash-verified
-# hash-verified archive.
+# archive.
 #
 # What this script installs outside the system package manager lives
 # under $HOME and is linked into ~/.local/bin, where make and the git
@@ -23,10 +23,6 @@ ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
 
 # Pinned versions, 2026-07-07
 NODE_VERSION="22.17.0"
-# The oldest node the frontend's dependencies accept: the "engines"
-# field of puppeteer-core 25.5.0, the most demanding of them, asks for
-# 22.12.0 or newer, 2026-09-29. An older installed node is not used.
-NODE_MIN_VERSION="22.12.0"
 NVM_VERSION="0.40.3"
 # sha256 of https://github.com/nvm-sh/nvm/archive/refs/tags/v0.40.3.tar.gz
 NVM_SHA256="5f4d6aaa04a177dc93c985e31dbc411ab6b8c6e1e21d8015dbc1372625fcd1d0"
@@ -140,22 +136,8 @@ ensure_nvm() {
     rm -rf "$tmp"
 }
 
-# node_ok: the node on PATH is at least NODE_MIN_VERSION. node itself
-# compares the two: major, then minor, then patch.
-node_ok() {
-    if missing node; then return 1; fi
-    node -e '
-        const have = process.versions.node.split(".").map(Number);
-        const want = process.argv[1].split(".").map(Number);
-        for (let i = 0; i < 3; i++) {
-            if (have[i] !== want[i]) process.exit(have[i] > want[i] ? 0 : 1);
-        }
-    ' "$NODE_MIN_VERSION"
-}
-
-# ensure_node: unless node_ok, install NODE_VERSION and link its node.
 ensure_node() {
-    if node_ok; then return 0; fi
+    if ! missing node; then return 0; fi
     ensure_nvm
     nvm_sh "nvm install $NODE_VERSION"
     link_bin "$HOME/.nvm/versions/node/v$NODE_VERSION/bin/node" node

script/cibuild

@@ -1,29 +1,15 @@
 #!/bin/sh
-# script/cibuild: run the CI build. It bootstraps first: a CI runner
+# script/cibuild: run the CI build: build the one image from Dockerfile,
-# checks out and runs this and nothing else, and script/fmt-check runs
+# whose stages run the checks as build steps (the backend's fmt-check,
-# the formatter on the host, which a pristine checkout cannot do.
+# lint and tests, and the frontend's test, lint and fmt-check). This is
-# --no-cache for the same reason as script/docker: the gate phases the
+# the only build step the Gitea workflow runs.
-# final stage depends on are RUN steps, and a cached one is a check that
-# did not run.
 set -eu
 
-SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd -P)"
+ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
-ROOT="$(cd "$SCRIPT_DIR/.." && pwd -P)"
 
 main() {
     cd "$ROOT"
-    "$SCRIPT_DIR/bootstrap"
+    timeout 300 docker build .
-    "$SCRIPT_DIR/check"
-    # Own line: a failing command substitution inside an argument does
-    # not trip `set -e`, so the inline form degrades silently to an
-    # empty constant. VERSION is computed here because .dockerignore
-    # excludes .git, so `git describe` in a build stage yields an empty
-    # version without failing.
-    version="$(git describe --tags --always --dirty 2>/dev/null || true)"
-    [ -n "$version" ] || version="unknown"
-    docker build --no-cache \
-        --build-arg VERSION="$version" \
-        -t "$("$SCRIPT_DIR/projectname")" .
 }
 
 main "$@"

script/frontend-viewport-test

@@ -64,15 +64,13 @@ main() {
     # nginx.conf is a template: the image renders it over its own
     # default.conf, with the same port and limit bin/entrypoint.sh uses.
     # The empty file it includes trusts no proxy, as bin/entrypoint.sh
-    # writes it when TRUSTED_PROXIES is unset. nginx.conf also includes
+    # writes it when TRUSTED_PROXIES is unset.
-    # the security headers, so the page runs under the shipped policy.
     docker run -d --rm --name "$SERVER" \
         --network "$NETWORK" --network-alias netwatch \
         -e PORT=8080 -e NGINX_ENVSUBST_FILTER='^PORT$' \
         -v "$ROOT/dist:/usr/share/nginx/html:ro" \
         -v "$ROOT/nginx.conf:/etc/nginx/templates/default.conf.template:ro" \
         -v /dev/null:/etc/nginx/trusted-proxies.conf:ro \
-        -v "$ROOT/security-headers.conf:/etc/nginx/security-headers.conf:ro" \
         "$SERVER_IMAGE" > /dev/null
 
     # The image's own entrypoint already exposes CDP on 9222 and passes

security-headers.conf

@@ -1,24 +0,0 @@
-# The security headers REPO_POLICIES.md requires on every response.
-# nginx.conf includes this file, which Dockerfile copies to
-# /etc/nginx/security-headers.conf. always sends each header on error
-# responses too.
-
-add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
-
-# Scripts and styles load only from the page's own origin. Inline ones
-# are blocked, style attributes in markup included, so style elements
-# through classes or element.style. data: images are for the favicon
-# in index.html. connect-src is * because the browser checks each probe in
-# src/main.js against it, and also every redirect the probe follows,
-# and several of those hosts redirect to others; a list of hosts here
-# would block those probes. It also covers the reports the page sends
-# to its own origin.
-add_header Content-Security-Policy "default-src 'self'; connect-src *; img-src 'self' data:; object-src 'none'; base-uri 'none'; form-action 'none'; frame-ancestors 'none'" always;
-
-add_header X-Frame-Options DENY always;
-add_header X-Content-Type-Options nosniff always;
-
-# The probed hosts are not told where the page is served from.
-add_header Referrer-Policy no-referrer always;
-
-add_header Permissions-Policy "accelerometer=(), camera=(), display-capture=(), geolocation=(), gyroscope=(), magnetometer=(), microphone=(), midi=(), payment=(), usb=()" always;

src/main.js

@@ -716,7 +716,7 @@ function hostRowHTML(host, index, showPin = true) {
         ${pinBtn}
         <div class="w-[420px] flex-shrink-0 grid grid-cols-[minmax(0,1fr)_auto] items-center">
           <div class="flex items-center gap-2 min-w-[200px]">
-            <div class="w-3 h-3 rounded-full flex-shrink-0 bg-[#6b7280]"></div>
+            <div class="w-3 h-3 rounded-full flex-shrink-0" style="background-color: ${latencyHex(null)}"></div>
             <span class="font-medium text-white truncate">${host.name}</span>
           </div>
           <div class="latency-value text-4xl font-bold tabular-nums text-right mt-3" data-host="${index}">