Rename discriminator to waf everywhere (closes #312)

The command is now `sww waf`, and the package is `internal/waf`. Types,
functions, files, tests, comments, docs, the Dockerfile, the runit
script, `script/`, compose examples, the log field `waf_line` and the
`X-From-Waf` test header follow. No behaviour changes, and no setting
changes name: rproxy already finds the waf through `SWRP_WAF_BACKEND`.

Done with one `sed -i` (Discriminator and DISCRIMINATOR to WAF,
discriminator to waf) over the files `git grep -i discriminator`
listed, as sneak allowed for this rename, then `git mv` for the
package and files. By hand afterwards: the header's spelling, which
the linter requires, and the padding after `waf` in `sww`'s usage
text.

Model: opus-5-5

internal/rproxy/rproxy.go

@@ -1,10 +1,10 @@
-// Package rproxy is the reverse proxy in front of one app that asks discriminator
-// about each request. It passes a request discriminator allows to the app and the
+// Package rproxy is the reverse proxy in front of one app that asks waf
+// about each request. It passes a request waf allows to the app and the
 // app's answer back, within the size and time limits. Any other answer from
-// discriminator goes to the visitor as discriminator gave it. SWRP_DEFAULT_DISPOSITION
-// decides only when discriminator cannot be connected to, does not answer at all, or
+// waf goes to the visitor as waf gave it. SWRP_DEFAULT_DISPOSITION
+// decides only when waf cannot be connected to, does not answer at all, or
 // does not answer within SWRP_TIMEOUT_MS. rproxy itself refuses a request with a
-// method it does not pass on, or one it cannot put to discriminator as the visitor
+// method it does not pass on, or one it cannot put to waf as the visitor
 // sent it. It keeps nothing between requests and never touches disk. "rproxy" in
 // SPEC.md says what it does.
 package rproxy
@@ -22,10 +22,10 @@ import (
 	"time"
 
 	"sneak.berlin/go/smallwebwaf/internal/config"
-	"sneak.berlin/go/smallwebwaf/internal/discriminator"
+	"sneak.berlin/go/smallwebwaf/internal/waf"
 )
 
-// How rproxy keeps connections to the app and to discriminator open between
+// How rproxy keeps connections to the app and to waf open between
 // requests.
 const (
 	idleConns       = 100
@@ -80,14 +80,14 @@ func New(params Params) *Server {
 	backend := params.Config.WAFBackend
 	errorLog := slog.NewLogLogger(params.ProcessLog.Handler(), slog.LevelWarn)
 	h := &handler{
-		config:                 params.Config,
-		requestLog:             params.RequestLog,
-		processLog:             params.ProcessLog,
-		errorLog:               errorLog,
-		transport:              newTransport(),
-		discriminatorTransport: newDiscriminatorTransport(),
+		config:       params.Config,
+		requestLog:   params.RequestLog,
+		processLog:   params.ProcessLog,
+		errorLog:     errorLog,
+		transport:    newTransport(),
+		wafTransport: newWAFTransport(),
 		reportURL: (&url.URL{
-			Scheme: backend.Scheme, Host: backend.Host, Path: discriminator.ReportPath,
+			Scheme: backend.Scheme, Host: backend.Host, Path: waf.ReportPath,
 		}).String(),
 	}
 
@@ -122,10 +122,10 @@ type handler struct {
 	requestLog io.Writer
 	processLog *slog.Logger
 	errorLog   *log.Logger
-	// transport carries requests to the app, and discriminatorTransport questions and
-	// reports to discriminator.
-	transport              http.RoundTripper
-	discriminatorTransport http.RoundTripper
+	// transport carries requests to the app, and wafTransport questions and
+	// reports to waf.
+	transport    http.RoundTripper
+	wafTransport http.RoundTripper
 	// reportURL is where the reports go.
 	reportURL string
 	// reports waits for the reports being sent. reportsMu guards starting one
@@ -147,11 +147,11 @@ func newTransport() *http.Transport {
 	}
 }
 
-// newDiscriminatorTransport returns what carries questions and reports to
-// discriminator. It speaks HTTP/1.1 only. Go's HTTP/2 client refuses to send
+// newWAFTransport returns what carries questions and reports to
+// waf. It speaks HTTP/1.1 only. Go's HTTP/2 client refuses to send
 // a visitor's Upgrade header, or a Connection header other than close or
-// keep-alive, and that would read as discriminator giving no answer.
-func newDiscriminatorTransport() *http.Transport {
+// keep-alive, and that would read as waf giving no answer.
+func newWAFTransport() *http.Transport {
 	transport := newTransport()
 	transport.Protocols = new(http.Protocols)
 	transport.Protocols.SetHTTP1(true)
@@ -160,15 +160,15 @@ func newDiscriminatorTransport() *http.Transport {
 }
 
 // ServeHTTP handles one request: it answers the health check itself, refuses a
-// request with a method it does not pass on or one it cannot put to discriminator as
+// request with a method it does not pass on or one it cannot put to waf as
 // the visitor sent it, and for any other request reads the first part of the
-// body, asks discriminator, and does what the answer says. Once the answer has ended,
+// body, asks waf, and does what the answer says. Once the answer has ended,
 // it writes the request's log line and sends its report.
 func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rq := h.newRequest(w, r)
 	defer rq.finish(r.Context())
 
-	if r.Method == http.MethodGet && r.URL.Path == discriminator.HealthPath {
+	if r.Method == http.MethodGet && r.URL.Path == waf.HealthPath {
 		rq.answerHealth()
 
 		return
@@ -201,9 +201,9 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	rq.noteAnswer(answer)
 
 	switch rq.disposition {
-	case discriminator.DispositionAllow:
+	case waf.DispositionAllow:
 		rq.passToApp(r.Context())
-	case discriminator.DispositionClose:
+	case waf.DispositionClose:
 		// This panic has Go's server close the connection without an answer,
 		// and log nothing; the deferred finish still runs.
 		panic(http.ErrAbortHandler)
@@ -213,7 +213,7 @@ func (h *handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 }
 
 // passToApp passes the request on to the app, unless a limit or its path keeps
-// it from the app. discriminator answers a path under ownEndpointPrefix itself, so
+// it from the app. waf answers a path under ownEndpointPrefix itself, so
 // such a request gets here only when SWRP_DEFAULT_DISPOSITION allowed it. ctx is the
 // request's own context.
 func (rq *request) passToApp(ctx context.Context) {