feat(lib): expose WEIGH matches as prometheus metrics

Signed-off-by: Xe Iaso <me@xeiaso.net>

docs/docs/CHANGELOG.md

@@ -13,10 +13,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 <!-- This changes the project to: -->
 
+- Expose WEIGHT rule matches as Prometheus metrics.
 - Allow more OCI registry clients [based on feedback](https://github.com/TecharoHQ/anubis/pull/1253#issuecomment-3506744184).
 - Expose services directory in the embedded `(data)` filesystem.
-- Add Ukrainian locale ([#1044](https://github.com/TecharoHQ/anubis/pull/1044))
-- Allow Renovate as an OCI registry client
+- Add Ukrainian locale ([#1044](https://github.com/TecharoHQ/anubis/pull/1044)).
+- Allow Renovate as an OCI registry client.
+- Properly handle 4in6 addresses so that IP matching works with those addresses.
 
 ## v1.23.1: Lyse Hext - Echo 1
 

lib/anubis.go

@@ -576,6 +576,7 @@ func (s *Server) check(r *http.Request, lg *slog.Logger) (policy.CheckResult, *p
 				return cr("bot/"+b.Name, b.Action, weight), &b, nil
 			case config.RuleWeigh:
 				lg.Debug("adjusting weight", "name", b.Name, "delta", b.Weight.Adjust)
+				policy.Applications.WithLabelValues("bot/"+b.Name, "WEIGH").Add(1)
 				weight += b.Weight.Adjust
 			}
 		}

lib/policy/checker.go

@@ -51,6 +51,11 @@ func (rac *RemoteAddrChecker) Check(r *http.Request) (bool, error) {
 		return false, fmt.Errorf("%w: %s is not an IP address: %w", ErrMisconfiguration, host, err)
 	}
 
+	// Convert IPv4-mapped IPv6 addresses to IPv4
+	if addr.Is6() && addr.Is4In6() {
+		addr = addr.Unmap()
+	}
+
 	return rac.prefixTable.Contains(addr), nil
 }
 

lib/policy/checker_test.go

@@ -21,6 +21,20 @@ func TestRemoteAddrChecker(t *testing.T) {
 			ok:    true,
 			err:   nil,
 		},
+		{
+			name:  "match_ipv4_in_ipv6",
+			cidrs: []string{"0.0.0.0/0"},
+			ip:    "::ffff:1.1.1.1",
+			ok:    true,
+			err:   nil,
+		},
+		{
+			name:  "match_ipv4_in_ipv6_hex",
+			cidrs: []string{"0.0.0.0/0"},
+			ip:    "::ffff:101:101",
+			ok:    true,
+			err:   nil,
+		},
 		{
 			name:  "match_ipv6",
 			cidrs: []string{"::/0"},