Rename internal/proxy to internal/servewaf (closes #173)

The package passes nothing on since the one-process mode went: it answers rproxy's questions, takes its reports and answers servewaf's own endpoints. It is now named after the command it serves, with `git mv`, and its constructor is `servewaf.New`. `SPEC.md` and the other documents follow. No change of behaviour.

Model: opus-5-5

internal/rproxy/servewaf.go

@@ -11,7 +11,7 @@ import (
 	"net/http"
 	"strings"
 
-	"sneak.berlin/go/smallwebwaf/internal/proxy"
+	"sneak.berlin/go/smallwebwaf/internal/servewaf"
 )
 
 // answerBodyMaxBytes is the most of the body of servewaf's answer that is read.
@@ -38,10 +38,10 @@ type servewafAnswer struct {
 // notes nothing, and no report is due for it: servewaf holds no decision to report
 // on.
 func (rq *request) noteAnswer(answer *servewafAnswer) {
-	disposition := answer.header.Get(proxy.DispositionHeader)
+	disposition := answer.header.Get(servewaf.DispositionHeader)
 
 	switch disposition {
-	case proxy.DispositionAllow, proxy.DispositionDeny, proxy.DispositionClose:
+	case servewaf.DispositionAllow, servewaf.DispositionDeny, servewaf.DispositionClose:
 		rq.disposition = disposition
 		rq.answered = true
 		rq.asn = answer.header.Get(asnHeader)
@@ -74,7 +74,7 @@ func (rq *request) handleNoUsableAnswer(ctx context.Context, err error) {
 		rq.disposition = rq.h.config.DefaultDisposition
 		rq.byDefault = true
 
-		if rq.disposition == proxy.DispositionAllow {
+		if rq.disposition == servewaf.DispositionAllow {
 			rq.passToApp(ctx)
 		} else {
 			rq.answer(http.StatusServiceUnavailable)
@@ -169,13 +169,13 @@ func (rq *request) newQuestion(ctx context.Context) (*http.Request, error) {
 	question.TransferEncoding = in.TransferEncoding
 
 	question.Header = in.Header.Clone()
-	question.Header.Set(proxy.ClientHeader, rq.client.String())
-	question.Header.Set(proxy.PeerHeader, rq.peer.String())
-	question.Header.Del(proxy.ContentLengthHeader)
+	question.Header.Set(servewaf.ClientHeader, rq.client.String())
+	question.Header.Set(servewaf.PeerHeader, rq.peer.String())
+	question.Header.Del(servewaf.ContentLengthHeader)
 
 	announced := in.Header.Get("Content-Length")
 	if announced != "" {
-		question.Header.Set(proxy.ContentLengthHeader, announced)
+		question.Header.Set(servewaf.ContentLengthHeader, announced)
 	}
 
 	question.Header.Set(requestIDHeader, rq.id)
@@ -196,7 +196,7 @@ func (rq *request) answerWith(answer *servewafAnswer) {
 
 	header := rq.out.Header()
 	maps.Copy(header, answer.header)
-	header.Del(proxy.DispositionHeader)
+	header.Del(servewaf.DispositionHeader)
 
 	// Go's server adds a Content-Type it guesses from the body to a response whose
 	// headers have no Content-Type key. The key with no value sends none.
@@ -210,7 +210,7 @@ func (rq *request) answerWith(answer *servewafAnswer) {
 // sendReport sends servewaf report on a goroutine of its own, so that the
 // visitor does not wait for it. The report goes on after ctx, the request's own
 // context, has ended.
-func (h *handler) sendReport(ctx context.Context, report *proxy.Report) {
+func (h *handler) sendReport(ctx context.Context, report *servewaf.Report) {
 	h.reportsMu.Lock()
 	defer h.reportsMu.Unlock()
 
@@ -228,7 +228,7 @@ func (h *handler) sendReport(ctx context.Context, report *proxy.Report) {
 
 // postReport posts report to servewaf, and waits for its answer for up to
 // SWRP_TIMEOUT_MS.
-func (h *handler) postReport(ctx context.Context, report *proxy.Report) error {
+func (h *handler) postReport(ctx context.Context, report *servewaf.Report) error {
 	body, err := json.Marshal(report)
 	if err != nil {
 		return fmt.Errorf("encode the report: %w", err)