rproxy and servewaf replace the one-process smallwebwaf (closes #172, closes #165)

`smallwebwaf` with no command now prints the commands and exits with status 2.
The image runs rproxy, or servewaf with SMALLWEBWAF_COMMAND=servewaf. The
passing-on code, its settings and its log fields and metric go. internal/proxy
keeps the checks, answers, reports and own endpoints; its tests run through the
real rproxy. The documents describe the pair.

Judgement call: clients.json keeps token_refused, since state files refuse unknown fields.
Deviation: script/gitea-requests sets SWWAF_LOG_REQUEST_HEADERS, to label requests.

Model: opus-5-5

internal/proxy/errorburst_test.go

@@ -17,8 +17,8 @@ import (
 
 const errorBurstThreshold = "SWWAF_ERROR_BURST_THRESHOLD"
 
-// refused is a request the tests here send, which smallwebwaf refuses
-// after a rule file match, or for a missing or wrong token.
+// refused is a request the tests here send, which servewaf refuses after a rule
+// file match.
 type refused int
 
 const (
@@ -27,11 +27,6 @@ const (
 	// banRule is one its ban rule refuses with 403, and bans the client
 	// for.
 	banRule
-	// noMetricsToken is one for the metrics without a token, and
-	// wrongAdminToken one for the bans with the metrics token, each
-	// refused with 401.
-	noMetricsToken
-	wrongAdminToken
 )
 
 // send sends r from the client at from, checks its answer and log line as
@@ -45,14 +40,6 @@ func (r refused) send(s *sender, from string) logLine {
 			requestlog.ActionRuleBlocked)
 	case banRule:
 		return s.request(from, probePath, http.StatusForbidden, requestlog.ActionBanned)
-	case noMetricsToken:
-		return s.request(from, proxy.MetricsPath, http.StatusUnauthorized,
-			requestlog.ActionAdmin)
-	case wrongAdminToken:
-		line, _ := s.requestWithHeader(from, proxy.BansPath, "Authorization: "+bearer,
-			http.StatusUnauthorized, requestlog.ActionAdmin)
-
-		return line
 	}
 
 	s.t.Fatalf("no request for the refusal %d", r)
@@ -60,7 +47,7 @@ func (r refused) send(s *sender, from string) logLine {
 	return logLine{}
 }
 
-// startForErrorBurst is startWithClock with testRules, both tokens and
+// startForErrorBurst is startWithClock with testRules, the metrics token and
 // SWWAF_ERROR_BURST_THRESHOLD at threshold, and the settings in env.
 func startForErrorBurst(
 	t *testing.T, threshold string, env map[string]string,
@@ -70,7 +57,6 @@ func startForErrorBurst(
 	settings := map[string]string{
 		errorBurstThreshold: threshold,
 		rulesDir:            writeRules(t, testRules),
-		adminToken:          adminSecret,
 		metricsToken:        token,
 	}
 	maps.Copy(settings, env)
@@ -87,14 +73,7 @@ func TestErrorBurstBreaksAtOneOverTheThreshold(t *testing.T) {
 		refusals []refused
 	}{
 		{"block rule", []refused{blockRule, blockRule, blockRule, blockRule}},
-		{
-			"missing or wrong token",
-			[]refused{noMetricsToken, wrongAdminToken, noMetricsToken, wrongAdminToken},
-		},
-		{
-			"a mix ending in a ban rule",
-			[]refused{blockRule, noMetricsToken, blockRule, banRule},
-		},
+		{"a ban rule last", []refused{blockRule, blockRule, blockRule, banRule}},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
 			t.Parallel()
@@ -130,13 +109,11 @@ func TestErrorBurstBreaksAtOneOverTheThreshold(t *testing.T) {
 func TestErrorBurstBanNotesHistoryAndMetrics(t *testing.T) {
 	t.Parallel()
 
-	const scraper = "192.0.2.200"
-
 	s, clk, server := startForErrorBurst(t, "2", nil)
 	start := clk.Now()
 
 	blockRule.send(s, client)
-	wrongAdminToken.send(s, client)
+	blockRule.send(s, client)
 	line := blockRule.send(s, client)
 
 	expires := start.Add(time.Hour)
@@ -173,19 +150,17 @@ func TestErrorBurstBanNotesHistoryAndMetrics(t *testing.T) {
 		t.Fatalf("bans\n%+v\nwant\n%+v", got, want)
 	}
 
-	wantOffences := ratelimit.Offences{Limit: 1, RuleBlocked: 2, TokenRefused: 1}
+	wantOffences := ratelimit.Offences{Limit: 1, RuleBlocked: 3}
 	if offences := historyOf(t, server, client).Offences; offences != wantOffences {
 		t.Errorf("history counts the offences %+v, want %+v", offences, wantOffences)
 	}
 
-	metrics := s.scrape(scraper)
+	metrics := s.scrape()
 	wantMetric(t, metrics, `smallwebwaf_rate_limit_hits_total{instance="app",`+
 		`kind="refusals",window="minute"}`, 1)
 	wantMetric(t, metrics, `smallwebwaf_offences_total{instance="app",kind="limit"}`, 1)
 	wantMetric(t, metrics,
-		`smallwebwaf_offences_total{instance="app",kind="rule_blocked"}`, 2)
-	wantMetric(t, metrics,
-		`smallwebwaf_offences_total{instance="app",kind="token_refused"}`, 1)
+		`smallwebwaf_offences_total{instance="app",kind="rule_blocked"}`, 3)
 	wantMetric(t, metrics, `smallwebwaf_bans_made_total{cause="limit",instance="app"}`, 1)
 }
 
@@ -291,19 +266,15 @@ func TestErrorBurstCountsEachClientTheChecksApplyTo(t *testing.T) {
 		allowNets: allowed, rateLimitExemptNets: exempt,
 	})
 
-	// A client in SWWAF_ALLOW_NETS still needs the token, but is not
-	// counted.
+	// A client in SWWAF_ALLOW_NETS is not refused, and so not counted.
 	for range 3 {
-		line := noMetricsToken.send(s, allowed)
-		if line.LimitHit != "" {
-			t.Errorf("log line has limit_hit %q, want none", line.LimitHit)
-		}
+		s.request(allowed, blockedPath, http.StatusOK, requestlog.ActionForward)
 	}
 
 	// One the rate limits do not apply to is.
-	noMetricsToken.send(s, exempt)
+	blockRule.send(s, exempt)
 
-	line := wrongAdminToken.send(s, exempt)
+	line := blockRule.send(s, exempt)
 	if line.LimitHit != requestlog.LimitHitErrorBurst {
 		t.Errorf("log line has limit_hit %q, want error_burst", line.LimitHit)
 	}
@@ -336,7 +307,6 @@ func TestObserveModeLogsAndAlertsTheErrorBurst(t *testing.T) {
 		mode:                observe,
 		errorBurstThreshold: "1",
 		rulesDir:            writeRules(t, testRules),
-		adminToken:          adminSecret,
 	})
 	start := clk.Now()
 	held := bans.Ban{
@@ -347,10 +317,11 @@ func TestObserveModeLogsAndAlertsTheErrorBurst(t *testing.T) {
 	}
 	server.Ledger.Load([]bans.Ban{held})
 
-	// Under a ban, enforce mode would have refused these before the
-	// endpoint, so their tokens are not counted.
+	// Under a ban, enforce mode would have refused these before the rule, so
+	// they are not counted.
 	for range 2 {
-		line := wrongAdminToken.send(s, otherClient)
+		line := s.request(otherClient, blockedPath, http.StatusOK,
+			requestlog.ActionForward)
 		wantWouldAction(t, line, requestlog.ActionBanned)
 
 		if line.LimitHit != "" {
@@ -360,7 +331,7 @@ func TestObserveModeLogsAndAlertsTheErrorBurst(t *testing.T) {
 
 	// The block rule's refusal, which enforce mode would have answered 403,
 	// is the second of the client's, and would have banned it.
-	wrongAdminToken.send(s, client)
+	s.request(client, blockedPath, http.StatusOK, requestlog.ActionForward)
 
 	line := s.request(client, blockedPath, http.StatusOK, requestlog.ActionForward)
 	wantWouldAction(t, line, requestlog.ActionRuleBlocked)