Read every setting through viper and rename the settings (closes #211)

Every setting of discriminator and rproxy is read through viper, in place
of the os.LookupEnv function Main passed down. NewViper turns AutomaticEnv
and AllowEmptyEnv on, so a setting that is set but empty reads as set. A
setting may also be given as a file, the _FILE form, which rproxy's
settings now have too; rproxy still writes nothing to disk.

The settings are renamed. Discriminator's take the prefix SWW_WAF_,
rproxy's take SWW_RPROXY_, and the shared SWW_COMMAND keeps SWW_. The Core
Rule Set's settings take SWW_WAF_CORE_RULE_SET_ rather than SWW_WAF_WAF_.
Every place a name appeared changed: the code, the viper keys, tests,
documents, examples, the README's settings table and the image files.

Model: deepseek-v4-pro

internal/rproxy/bodies.go

@@ -10,16 +10,16 @@ import (
 )
 
 // errResponseTooLarge ends an app's response body that is longer than
-// SWRP_MAX_RESPONSE_SIZE.
+// SWW_RPROXY_MAX_RESPONSE_SIZE.
 var errResponseTooLarge = errors.New(
-	"the response body is over SWRP_MAX_RESPONSE_SIZE")
+	"the response body is over SWW_RPROXY_MAX_RESPONSE_SIZE")
 
 // requestBody is the visitor's request body. rproxy first reads up to the first
 // 64 KiB of it into held, and then, on its way to the app, the transport reads
 // it on a goroutine of its own.
 type requestBody struct {
 	// body is the visitor's body, ending in an *http.MaxBytesError past
-	// SWRP_MAX_REQUEST_SIZE.
+	// SWW_RPROXY_MAX_REQUEST_SIZE.
 	body io.ReadCloser
 	rq   *request
 	// held is the part read before the request goes to the app, which Read gives
@@ -68,7 +68,7 @@ func (b *requestBody) Close() error {
 // responseBody is the app's response body on its way to the visitor.
 type responseBody struct {
 	// body is the app's body, ending in an *http.MaxBytesError past
-	// SWRP_MAX_RESPONSE_SIZE.
+	// SWW_RPROXY_MAX_RESPONSE_SIZE.
 	body io.ReadCloser
 	rq   *request
 }

internal/rproxy/discriminator.go

@@ -65,9 +65,9 @@ func (rq *request) handleNoUsableAnswer(ctx context.Context, err error) {
 		rq.answer(http.StatusBadGateway)
 	default:
 		// discriminator cannot be connected to, does not answer at all, or does not answer
-		// within SWRP_TIMEOUT_MS. A request that keeps discriminator busy past
-		// SWRP_TIMEOUT_MS, like any request while discriminator is overloaded, gets
-		// SWRP_DEFAULT_DISPOSITION here. deny closes this, at the cost of answering 503
+		// within SWW_RPROXY_TIMEOUT_MS. A request that keeps discriminator busy past
+		// SWW_RPROXY_TIMEOUT_MS, like any request while discriminator is overloaded, gets
+		// SWW_RPROXY_DEFAULT_DISPOSITION here. deny closes this, at the cost of answering 503
 		// whenever discriminator is slow. Making such requests hard to send is
 		// https://git.eeqj.de/sneak/smallwebwaf/issues/182.
 		rq.h.processLog.Warn("discriminator gave no answer", "error", err.Error())
@@ -84,7 +84,7 @@ func (rq *request) handleNoUsableAnswer(ctx context.Context, err error) {
 }
 
 // ask sends discriminator the question, and returns its answer, which must have come
-// whole within SWRP_TIMEOUT_MS. It ends when ctx does, as when the visitor goes
+// whole within SWW_RPROXY_TIMEOUT_MS. It ends when ctx does, as when the visitor goes
 // away.
 func (rq *request) ask(ctx context.Context) (*discriminatorAnswer, error) {
 	ctx, cancel := context.WithTimeout(ctx, rq.h.config.Timeout)
@@ -228,7 +228,7 @@ func (h *handler) sendReport(ctx context.Context, report *discriminator.Report)
 }
 
 // postReport posts report to discriminator, and waits for its answer for up to
-// SWRP_TIMEOUT_MS.
+// SWW_RPROXY_TIMEOUT_MS.
 func (h *handler) postReport(ctx context.Context, report *discriminator.Report) error {
 	body, err := json.Marshal(report)
 	if err != nil {

internal/rproxy/limits_test.go

@@ -33,13 +33,9 @@ func announcedLength(size int) string {
 func TestServerHasTheFixedLimits(t *testing.T) {
 	t.Parallel()
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
-		if name == "SWRP_WAF_BACKEND" {
-			return nowhere, true
-		}
-
-		return "", false
-	})
+	cfg, err := config.RProxyFromEnvironment(viperFrom(map[string]string{
+		"SWW_RPROXY_WAF_BACKEND": nowhere,
+	}))
 	if err != nil {
 		t.Fatalf("settings: %v", err)
 	}

internal/rproxy/request.go

@@ -50,10 +50,10 @@ type request struct {
 	start       time.Time
 
 	// disposition is what is done with the request: discriminator's valid disposition,
-	// or SWRP_DEFAULT_DISPOSITION. It is "" when neither gave one.
+	// or SWW_RPROXY_DEFAULT_DISPOSITION. It is "" when neither gave one.
 	disposition string
 	// answered is true when discriminator gave disposition, which makes a report due,
-	// and byDefault when SWRP_DEFAULT_DISPOSITION did.
+	// and byDefault when SWW_RPROXY_DEFAULT_DISPOSITION did.
 	answered  bool
 	byDefault bool
 	// asn and country are discriminator's X-Client-ASN and X-Client-Country, for the
@@ -118,10 +118,10 @@ func (rq *request) answerHealth() {
 }
 
 // readFirstPartOfBody reads up to the first 64 KiB of the body into memory,
-// within SWRP_MAX_REQUEST_TIME_MS, and reports whether the request goes on. A
+// within SWW_RPROXY_MAX_REQUEST_TIME_MS, and reports whether the request goes on. A
 // visitor too slow to send it is answered 408. For a malformed chunk, or a
 // visitor that went away or stopped its sending side, the connection is closed
-// without an answer. A body over SWRP_MAX_REQUEST_SIZE goes on with the part
+// without an answer. A body over SWW_RPROXY_MAX_REQUEST_SIZE goes on with the part
 // read, so that discriminator is asked first; passToApp then refuses it.
 func (rq *request) readFirstPartOfBody() bool {
 	if rq.body == nil {
@@ -190,7 +190,7 @@ func (rq *request) forward(ctx context.Context) {
 }
 
 // rewrite makes the request the app receives: the visitor's request, unchanged,
-// sent to SWRP_UPSTREAM_URL, with the forwarded headers and the request's id set,
+// sent to SWW_RPROXY_UPSTREAM_URL, with the forwarded headers and the request's id set,
 // without any X-Client-ASN or X-Client-Country the visitor sent, and with
 // discriminator's.
 func (rq *request) rewrite(pr *httputil.ProxyRequest) {
@@ -325,7 +325,7 @@ func (rq *request) send(status int, body []byte) {
 
 // prepareOwnAnswer readies the connection for an answer rproxy gives itself: the
 // reading of a body that has not arrived whole ends at deadline, and the answer
-// has SWRP_MAX_RESPONSE_TIME_MS from now to reach the visitor, even when the app
+// has SWW_RPROXY_MAX_RESPONSE_TIME_MS from now to reach the visitor, even when the app
 // used that time up first.
 func (rq *request) prepareOwnAnswer(deadline time.Time) {
 	rq.stopReadingBody(deadline)
@@ -419,7 +419,7 @@ func (rq *request) bytesEachWay() (int64, int64) {
 }
 
 // requestDeadline is when the visitor must have sent its whole request, or zero
-// when SWRP_MAX_REQUEST_TIME_MS is off.
+// when SWW_RPROXY_MAX_REQUEST_TIME_MS is off.
 func (rq *request) requestDeadline() time.Time {
 	limit := rq.h.config.MaxRequestTime
 	if limit == 0 {
@@ -440,7 +440,7 @@ func (rq *request) stopReadingBody(deadline time.Time) {
 	_ = rq.rc.SetReadDeadline(deadline)
 }
 
-// startRequestTimer starts SWRP_MAX_REQUEST_TIME_MS, which runs from the
+// startRequestTimer starts SWW_RPROXY_MAX_REQUEST_TIME_MS, which runs from the
 // request's headers being read until the app has been sent the whole request.
 func (rq *request) startRequestTimer() {
 	deadline := rq.requestDeadline()
@@ -454,7 +454,7 @@ func (rq *request) startRequestTimer() {
 	rq.requestTimer = time.AfterFunc(time.Until(deadline), rq.requestTimedOut)
 }
 
-// requestTimedOut is called when SWRP_MAX_REQUEST_TIME_MS runs out while the
+// requestTimedOut is called when SWW_RPROXY_MAX_REQUEST_TIME_MS runs out while the
 // request is still on its way to the app. The answer names the side rproxy was
 // waiting on at that moment: 408 when it was waiting for the visitor to send more
 // of its body, 504 when it was waiting for the app to be reached or to take what
@@ -500,7 +500,7 @@ func (rq *request) gotFirstResponseByte() {
 }
 
 // wroteRequest is called once the app has been sent the whole request:
-// SWRP_MAX_REQUEST_TIME_MS ends and SWRP_MAX_RESPONSE_TIME_MS starts.
+// SWW_RPROXY_MAX_REQUEST_TIME_MS ends and SWW_RPROXY_MAX_RESPONSE_TIME_MS starts.
 func (rq *request) wroteRequest(info httptrace.WroteRequestInfo) {
 	if info.Err != nil {
 		return // the transport gives up, or tries again
@@ -524,7 +524,7 @@ func (rq *request) wroteRequest(info httptrace.WroteRequestInfo) {
 	}
 }
 
-// responseTimedOut is called when SWRP_MAX_RESPONSE_TIME_MS runs out before the
+// responseTimedOut is called when SWW_RPROXY_MAX_RESPONSE_TIME_MS runs out before the
 // app has sent its whole answer.
 func (rq *request) responseTimedOut() {
 	rq.mu.Lock()
@@ -539,7 +539,7 @@ func (rq *request) responseTimedOut() {
 // answer before the visitor has sent its whole body, as with a 404 it sends
 // without reading it. The time limits then run on: until the transport's read of
 // the body returns, Go's server cannot send the answer, and
-// SWRP_MAX_REQUEST_TIME_MS is what ends that read for a visitor that stops
+// SWW_RPROXY_MAX_REQUEST_TIME_MS is what ends that read for a visitor that stops
 // sending.
 func (rq *request) responseReceived() {
 	if rq.body != nil && !rq.body.received.Load() {
@@ -549,7 +549,7 @@ func (rq *request) responseReceived() {
 	rq.stopTimers()
 }
 
-// setResponseDeadline sets SWRP_MAX_RESPONSE_TIME_MS on the connection to the
+// setResponseDeadline sets SWW_RPROXY_MAX_RESPONSE_TIME_MS on the connection to the
 // visitor: the app's answer must reach the visitor within it of the end of the
 // request.
 func (rq *request) setResponseDeadline() {

internal/rproxy/rproxy.go

@@ -1,9 +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
 // 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
+// discriminator goes to the visitor as discriminator gave it.
+// SWW_RPROXY_DEFAULT_DISPOSITION
 // decides only when discriminator cannot be connected to, does not answer at all, or
-// does not answer within SWRP_TIMEOUT_MS. rproxy itself refuses a request with a
+// does not answer within SWW_RPROXY_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
 // sent it. It keeps nothing between requests and never touches disk. "rproxy" in
 // SPEC.md says what it does.
@@ -71,7 +72,7 @@ type Server struct {
 
 // New returns the server `sww rproxy` runs. Go's server itself refuses
 // a request line and headers over requestHeaderMaxBytes, with 431, closes a
-// connection idle for idleTimeout, and applies SWRP_MAX_REQUEST_TIME_MS while
+// connection idle for idleTimeout, and applies SWW_RPROXY_MAX_REQUEST_TIME_MS while
 // the headers arrive. The handler applies the time and size limits from then
 // on.
 func New(params Params) *Server {
@@ -103,7 +104,7 @@ func New(params Params) *Server {
 }
 
 // WaitForReports returns once the reports being sent have gone or failed,
-// which SWRP_TIMEOUT_MS bounds. Any report after this call is dropped: that of
+// which SWW_RPROXY_TIMEOUT_MS bounds. Any report after this call is dropped: that of
 // a WebSocket that closes while rproxy stops, for one.
 func (s *Server) WaitForReports() {
 	s.h.reportsMu.Lock()
@@ -212,7 +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 adminPrefix itself, so such a
-// request gets here only when SWRP_DEFAULT_DISPOSITION allowed it. ctx is the
+// request gets here only when SWW_RPROXY_DEFAULT_DISPOSITION allowed it. ctx is the
 // request's own context.
 func (rq *request) passToApp(ctx context.Context) {
 	maxBytes := rq.h.config.MaxRequestSize

internal/rproxy/rproxy_test.go

@@ -18,6 +18,8 @@ import (
 	"testing"
 	"time"
 
+	"github.com/spf13/viper"
+
 	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/discriminator"
 	"sneak.berlin/go/smallwebwaf/internal/requestlog"
@@ -43,13 +45,13 @@ const (
 
 // The settings the tests set.
 const (
-	timeoutSetting     = "SWRP_TIMEOUT_MS"
-	defaultDisposition = "SWRP_DEFAULT_DISPOSITION"
-	trustedProxies     = "SWRP_TRUSTED_PROXIES"
-	maxRequestSize     = "SWRP_MAX_REQUEST_SIZE"
-	maxResponseSize    = "SWRP_MAX_RESPONSE_SIZE"
-	maxRequestTime     = "SWRP_MAX_REQUEST_TIME_MS"
-	maxResponseTime    = "SWRP_MAX_RESPONSE_TIME_MS"
+	timeoutSetting     = "SWW_RPROXY_TIMEOUT_MS"
+	defaultDisposition = "SWW_RPROXY_DEFAULT_DISPOSITION"
+	trustedProxies     = "SWW_RPROXY_TRUSTED_PROXIES"
+	maxRequestSize     = "SWW_RPROXY_MAX_REQUEST_SIZE"
+	maxResponseSize    = "SWW_RPROXY_MAX_RESPONSE_SIZE"
+	maxRequestTime     = "SWW_RPROXY_MAX_REQUEST_TIME_MS"
+	maxResponseTime    = "SWW_RPROXY_MAX_RESPONSE_TIME_MS"
 )
 
 // The headers the tests set and look at.
@@ -345,6 +347,17 @@ func startServer(
 	return addr, out, server
 }
 
+// viperFrom returns a viper Set with each of settings, as the viper
+// config.NewViper returns one bound to a process's environment.
+func viperFrom(settings map[string]string) *viper.Viper {
+	v := viper.New()
+	for name, value := range settings {
+		v.Set(name, value)
+	}
+
+	return v
+}
+
 // startServerLogging is startServer with rproxy's request lines going to
 // requestLog and its process lines to processLog.
 func startServerLogging(
@@ -354,15 +367,11 @@ func startServerLogging(
 	t.Helper()
 
 	settings := map[string]string{
-		"SWRP_WAF_BACKEND": backend, "SWRP_UPSTREAM_URL": appURL,
+		"SWW_RPROXY_WAF_BACKEND": backend, "SWW_RPROXY_UPSTREAM_URL": appURL,
 	}
 	maps.Copy(settings, env)
 
-	cfg, err := config.RProxyFromEnvironment(func(name string) (string, bool) {
-		value, ok := settings[name]
-
-		return value, ok
-	})
+	cfg, err := config.RProxyFromEnvironment(viperFrom(settings))
 	if err != nil {
 		t.Fatalf("settings %v: %v", settings, err)
 	}