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

Every setting of waf 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: waf'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_.

Model: deepseek-v4-pro (first version); opus-5-5 (rework)

internal/rproxy/request.go

@@ -34,14 +34,14 @@ const plainText = "text/plain; charset=utf-8"
 
 // minSendTime is the least time to send an answer rproxy gives itself, or the
 // status and headers of the app's answer. A shorter time can run out before the
-// first byte is written, on a busy host or as SWRP_MAX_RESPONSE_TIME_MS runs out,
+// first byte is written, on a busy host or as SWW_RPROXY_MAX_RESPONSE_TIME_MS runs out,
 // and the visitor then gets a closed connection and no answer.
 const minSendTime = 10 * time.Second
 
 // errResponseTooLate refuses an app's answer that arrives once
-// SWRP_MAX_RESPONSE_TIME_MS has run out.
+// SWW_RPROXY_MAX_RESPONSE_TIME_MS has run out.
 var errResponseTooLate = errors.New(
-	"the answer arrived after SWRP_MAX_RESPONSE_TIME_MS ran out")
+	"the answer arrived after SWW_RPROXY_MAX_RESPONSE_TIME_MS ran out")
 
 // request is one request on its way through rproxy, from the moment its headers
 // have been read to its log line and report.
@@ -61,10 +61,10 @@ type request struct {
 	start       time.Time
 
 	// disposition is what is done with the request: waf'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 waf 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 waf's X-Client-ASN and X-Client-Country, for the
@@ -127,10 +127,10 @@ 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 waf is asked first; passToApp then refuses it.
 func (rq *request) readFirstPartOfBody() bool {
 	if rq.body == nil {
@@ -198,7 +198,7 @@ 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
 // waf's.
 func (rq *request) rewrite(pr *httputil.ProxyRequest) {
@@ -247,7 +247,7 @@ func (rq *request) modifyResponse(res *http.Response) error {
 
 	requestEnd := rq.endRequest()
 
-	// An answer that arrives once SWRP_MAX_RESPONSE_TIME_MS has run out is not
+	// An answer that arrives once SWW_RPROXY_MAX_RESPONSE_TIME_MS has run out is not
 	// passed on: the visitor is answered 504.
 	limit := rq.h.config.MaxResponseTime
 	if limit > 0 && !time.Now().Before(requestEnd.Add(limit)) {
@@ -273,7 +273,7 @@ func (rq *request) modifyResponse(res *http.Response) error {
 	rq.closeAfterAnswer()
 
 	// An answer that arrives before the app has been sent the whole request ends
-	// the request, and SWRP_MAX_RESPONSE_TIME_MS starts.
+	// the request, and SWW_RPROXY_MAX_RESPONSE_TIME_MS starts.
 	rq.startResponseTimer(requestEnd)
 
 	res.Body = &responseBody{body: limitBody(res.Body, maxBytes), rq: rq}
@@ -361,7 +361,7 @@ func (rq *request) closeAfterAnswer() {
 
 // 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, and at least minSendTime.
 func (rq *request) prepareOwnAnswer(deadline time.Time) {
 	rq.stopReadingBody(deadline)
@@ -470,7 +470,7 @@ 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 {
@@ -511,7 +511,7 @@ func (rq *request) stopPassingOnBody(deadline time.Time) {
 	rq.stopReadingBody(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()
@@ -525,7 +525,7 @@ 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
@@ -552,7 +552,7 @@ func (rq *request) requestTimedOut() {
 }
 
 // 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
@@ -567,7 +567,7 @@ func (rq *request) wroteRequest(info httptrace.WroteRequestInfo) {
 	rq.startResponseTimer(requestEnd)
 }
 
-// startResponseTimer starts SWRP_MAX_RESPONSE_TIME_MS, which runs from
+// startResponseTimer starts SWW_RPROXY_MAX_RESPONSE_TIME_MS, which runs from
 // requestEnd, unless it has started already.
 func (rq *request) startResponseTimer(requestEnd time.Time) {
 	limit := rq.h.config.MaxResponseTime
@@ -586,7 +586,7 @@ func (rq *request) startResponseTimer(requestEnd time.Time) {
 		rq.responseTimedOut)
 }
 
-// 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()
@@ -604,7 +604,7 @@ func (rq *request) responseReceived() {
 
 // setResponseDeadline sends the status and headers of the app's answer, with
 // at least minSendTime, before ReverseProxy reads the answer's body, and then
-// the rest has until SWRP_MAX_RESPONSE_TIME_MS after the end of the request.
+// the rest has until SWW_RPROXY_MAX_RESPONSE_TIME_MS after the end of the request.
 func (rq *request) setResponseDeadline() {
 	limit := rq.h.config.MaxResponseTime
 	if limit == 0 {