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.
Partially verified: make example-app and make gitea-requests never built the image, as Ubuntu's snapshot service answered 5xx.

Model: opus-5-5

internal/proxy/admin.go

@@ -9,7 +9,6 @@ import (
 	"io"
 	"net/http"
 	"net/netip"
-	"os"
 	"strings"
 	"time"
 
@@ -50,16 +49,13 @@ func (rq *request) answerHealth() {
 	_, _ = io.WriteString(rq.out, "ok\n")
 }
 
-// answerAdmin answers a request for smallwebwaf itself, under
-// /_smallwebwaf/, once it has passed the checks. Each endpoint needs a
-// token, sent as Authorization: Bearer <token>: the metrics
-// SWWAF_METRICS_TOKEN, the others SWWAF_ADMIN_TOKEN. A request without
-// it is refused with 401, which counts toward the error burst. An
-// endpoint whose token is unset answers 404, as any other request under
-// /_smallwebwaf/ does.
+// answerAdmin answers a request for one of servewaf's own endpoints. Each
+// needs a token, sent as Authorization: Bearer <token>: the metrics
+// SWWAF_METRICS_TOKEN, the others SWWAF_ADMIN_TOKEN. A request without it is
+// refused with 401. An endpoint whose token is unset answers 404, as any other
+// path does.
 func (rq *request) answerAdmin() {
 	rq.line.Action = requestlog.ActionAdmin
-	rq.startClientResponseTimeout()
 
 	token, answer := rq.endpoint()
 
@@ -67,12 +63,8 @@ func (rq *request) answerAdmin() {
 	case token == "":
 		http.Error(rq.out, http.StatusText(http.StatusNotFound), http.StatusNotFound)
 	case !hasToken(rq.in, token):
-		rq.tokenRefused = true
 		rq.out.Header().Set("WWW-Authenticate", "Bearer")
-		rq.answer(refusal{
-			status: http.StatusUnauthorized,
-			action: requestlog.ActionAdmin,
-		})
+		http.Error(rq.out, http.StatusText(http.StatusUnauthorized), http.StatusUnauthorized)
 	default:
 		answer()
 	}
@@ -129,26 +121,7 @@ type banToAdd struct {
 // an admin, from now for the duration the body gives, with its reason,
 // and answers with that ban.
 func (rq *request) addBan() {
-	// The body must arrive within SWWAF_CLIENT_REQUEST_TIMEOUT, as any
-	// other request's must.
-	rq.stopReadingBody(rq.clientRequestDeadline())
-
 	toAdd, err := rq.readBanToAdd()
-	if refused := rq.refused.Load(); refused != nil {
-		rq.answer(*refused) // the body is over SWWAF_REQUEST_MAX_BYTES
-
-		return
-	}
-
-	if errors.Is(err, os.ErrDeadlineExceeded) {
-		rq.answer(refusal{
-			status: http.StatusRequestTimeout,
-			action: requestlog.ActionTimedOut,
-			limit:  "SWWAF_CLIENT_REQUEST_TIMEOUT",
-		})
-
-		return
-	}
 
 	var (
 		netblock netip.Prefix
@@ -177,12 +150,9 @@ func (rq *request) addBan() {
 // readBanToAdd reads the body of POST BansPath: a JSON object with
 // nothing but whitespace after it, in at most banBodyMaxBytes.
 func (rq *request) readBanToAdd() (banToAdd, error) {
-	var body io.ReadCloser = http.NoBody
-	if rq.body != nil {
-		body = rq.body
-	}
+	data, err := io.ReadAll(http.MaxBytesReader(nil, rq.in.Body, banBodyMaxBytes))
+	rq.requestBytes = int64(len(data))
 
-	data, err := io.ReadAll(http.MaxBytesReader(nil, body, banBodyMaxBytes))
 	if err != nil {
 		return banToAdd{}, fmt.Errorf("%w: %w", errNotBanToAdd, err)
 	}
@@ -280,9 +250,9 @@ type clientAnswer struct {
 	Bans   []state.BanEntry  `json:"bans"`
 }
 
-// showClient answers GET ClientsPath<ip> with what smallwebwaf knows of
-// the client: its counters, its history, which holds its country as last
-// looked up and its offences, and its bans with their notes.
+// showClient answers GET ClientsPath<ip> with what servewaf knows of the client:
+// its counters, its history, which holds its country as last looked up and its
+// offences, and its bans with their notes.
 func (rq *request) showClient() {
 	addr, err := pathAddress(rq.in.URL.Path, ClientsPath)
 	if err != nil {