servewaf always answers rproxy well within its time limit (closes #182)

A question waits on GeoJS at most 800ms, the new default of
SWWAF_LOOKUP_TIMEOUT. It does not wait at all when the checks will refuse
it whatever GeoJS answers. Just before the Core Rule Set, servewaf refuses
more than 50 cookies or 100 header fields with 431.

Shared default changed: SWWAF_LOOKUP_TIMEOUT also applies to smallwebwaf
with no command.
Judgement call: SWWAF_REPUTATION_TIMEOUT stays 2s, since no request waits
on the DNS blocklists or AbuseIPDB.

Model: opus-5-5

docs/metrics.md

@@ -17,7 +17,8 @@ label as `exported_instance` unless the scrape sets `honor_labels: true`.
 
 - `smallwebwaf_rate_limit_hits_total`, by `window` and by `kind` (`requests`,
   `bytes` or `refusals`);
-- `smallwebwaf_size_and_time_limit_hits_total`, by `limit`, the setting passed;
+- `smallwebwaf_size_and_time_limit_hits_total`, by `limit`, the setting passed.
+  `servewaf`'s header limits have no setting, so it leaves them out;
 - `smallwebwaf_offences_total`, by `kind`;
 - `smallwebwaf_bans_made_total`, by `cause`;
 - `smallwebwaf_active_bans` and `smallwebwaf_permanent_bans`.

docs/request-log.md

@@ -67,7 +67,8 @@ Every line has:
       CrowdSec decision, each of which bans the client;
     - `country_denied`, `rate_limited`, `rule_blocked` and `waf_blocked`:
       refused by that check;
-    - `too_large` and `timed_out`: a size or time limit was passed;
+    - `too_large`: a size limit was passed, or a header limit in `servewaf`;
+    - `timed_out`: a time limit was passed;
     - `upstream_error`: the app could not be reached, or its answer broke off;
     - `admin`: answered at one of `smallwebwaf`'s own endpoints.
 - `would_action`: in `observe` mode, what `enforce` mode would have done with a

docs/settings.md

@@ -157,7 +157,7 @@ that take `off`, the `_FILE` form, and what each group does and why.
     - an anomaly threshold per AS number.
 - `SWWAF_LOOKUP_DB_PATH` (default empty): the IPinfo Lite database file, in its
   `.mmdb` form, for `SWWAF_LOOKUP_SOURCE=file`.
-- `SWWAF_LOOKUP_TIMEOUT` (default `1s`): how long a request waits for its
+- `SWWAF_LOOKUP_TIMEOUT` (default `800ms`): how long a request waits for its
   client's first answer from GeoJS, and how long a request to GeoJS may take. A
   duration; never `off`.
 - `SWWAF_ADD_LOOKUP_HEADERS` (default `false`): `true` passes the app the
@@ -340,7 +340,10 @@ A few limits are fixed rather than settings:
 - at most 1,000 DNS blocklist queries are under way at once;
 - at most 20,000 anomaly counters are kept;
 - each alert destination's queue holds at most 1,000 alerts;
-- `servewaf` holds at most 10,000 answered requests awaiting their reports.
+- `servewaf` holds at most 10,000 answered requests awaiting their reports;
+- `servewaf` refuses a request with more than 50 cookies or more than 100 header
+  fields (see "Answering in time" under "`servewaf`" in
+  [`SPEC.md`](../SPEC.md)).
 
 ## `servewaf`
 
@@ -358,3 +361,9 @@ at start still shows them.
 request to an app. `SWWAF_WAF_BODY_LIMIT` has an effect up to 64 KiB less one
 byte, whatever its value. A question carries no more of a body than 64 KiB (see
 "`servewaf`" in [`SPEC.md`](../SPEC.md)).
+
+`SWWAF_LOOKUP_TIMEOUT` is the longest a question waits on an outside source.
+Keep it well under `rproxy`'s `SWRP_TIMEOUT_MS`, as the default is. No question
+waits for `SWWAF_REPUTATION_TIMEOUT`, since the DNS blocklists and AbuseIPDB are
+asked in the background (see "Answering in time" under "`servewaf`" in
+[`SPEC.md`](../SPEC.md)).