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.

Model: opus-5-5

internal/requestlog/requestlog.go

@@ -14,19 +14,13 @@ import (
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 )
 
-// The action a request line names: what smallwebwaf did with the
-// request.
+// The action a request line names: what servewaf did with the request.
 const (
-	// ActionForward is a request passed to the app.
+	// ActionForward is a request servewaf allowed, which rproxy passes to the
+	// app.
 	ActionForward = "forward"
-	// ActionTooLarge is a request or response over its size limit, or, in
-	// servewaf, a request over the header limits.
+	// ActionTooLarge is a request over the header limits.
 	ActionTooLarge = "too_large"
-	// ActionTimedOut is a request or response that ran out of time.
-	ActionTimedOut = "timed_out"
-	// ActionUpstreamError is a request the app could not be reached
-	// for, or whose answer could not be passed on.
-	ActionUpstreamError = "upstream_error"
 	// ActionRateLimited is a request refused because it took its client
 	// over a rate limit, which bans the client.
 	ActionRateLimited = "rate_limited"
@@ -48,8 +42,8 @@ const (
 	ActionDenied = "denied"
 	// ActionCountryDenied is a request refused for its client's country.
 	ActionCountryDenied = "country_denied"
-	// ActionAdmin is a request smallwebwaf answered at one of its own
-	// endpoints, under /_smallwebwaf/.
+	// ActionAdmin is a request servewaf answered at one of its own endpoints,
+	// or a question about a path under /_smallwebwaf/.
 	ActionAdmin = "admin"
 )
 
@@ -86,8 +80,8 @@ type Line struct {
 	// two lines about a question.
 	ServeWAFLine string `json:"servewaf_line,omitempty"`
 
-	// The standard web log fields. Scheme is how the client reached
-	// smallwebwaf, or the trusted proxy in front of it.
+	// The standard web log fields. Scheme is how the client reached rproxy, or
+	// the trusted proxy in front of it.
 	Time          string `json:"time"`
 	Instance      string `json:"instance"`
 	ClientIP      string `json:"client_ip"`
@@ -103,8 +97,8 @@ type Line struct {
 	Referer       string `json:"referer"`
 	UserAgent     string `json:"user_agent"`
 
-	// Request detail. RequestID is the X-Request-ID a trusted proxy sent,
-	// or a new one, and is sent on to the app. ForwardedFor is the
+	// Request detail. RequestID is the id rproxy made for the request, or for a
+	// request to servewaf's own endpoints a new one. ForwardedFor is the
 	// X-Forwarded-For header as received. ClientGroup is the netblock the
 	// client is counted as. ASN, ASName and Country are the client's AS
 	// number, AS name and country, as looked up.
@@ -123,17 +117,10 @@ type Line struct {
 	RequestHeaders   map[string]string `json:"request_headers,omitempty"`
 	HasAuthorization bool              `json:"has_authorization,omitempty"`
 	HasCookie        bool              `json:"has_cookie,omitempty"`
-	// Websocket is true when the connection was upgraded, as for a
-	// WebSocket.
-	Websocket bool `json:"websocket,omitempty"`
 
-	// Response detail, from the headers of the answer: the app's, as
-	// passed on, or those of smallwebwaf's own. Aborted is true when the
-	// client went away early.
+	// Response detail, of servewaf's own answer. Aborted is true when rproxy, or
+	// the admin's tool, went away before the answer.
 	ResponseContentType string `json:"response_content_type,omitempty"`
-	UpstreamStatus      int    `json:"upstream_status,omitempty"`
-	CacheControl        string `json:"cache_control,omitempty"`
-	Location            string `json:"location,omitempty"`
 	Aborted             bool   `json:"aborted,omitempty"`
 
 	// The decision.
@@ -183,17 +170,13 @@ type Line struct {
 
 	// The timings, in milliseconds. DurationChecks is the time until the
 	// checks were done, and DurationWAF the part of it the Core Rule Set
-	// took. DurationUpstreamConnect, DurationUpstreamFirstByte and
-	// DurationUpstreamTotal run from when the request was handed to the
-	// app: until there was a connection to it, until the first byte of its
-	// answer arrived, and until the end. Each but DurationTotal is nil for
-	// a request that did not get that far.
-	DurationTotal             float64  `json:"duration_total"`
-	DurationChecks            *float64 `json:"duration_checks,omitempty"`
-	DurationWAF               *float64 `json:"duration_waf,omitempty"`
-	DurationUpstreamConnect   *float64 `json:"duration_upstream_connect,omitempty"`
-	DurationUpstreamFirstByte *float64 `json:"duration_upstream_first_byte,omitempty"`
-	DurationUpstreamTotal     *float64 `json:"duration_upstream_total,omitempty"`
+	// took. DurationUpstreamTotal is what the report of an allowed request gives,
+	// from the hand-over to the app until the end of its answer. Each but
+	// DurationTotal is nil for a request that did not get that far.
+	DurationTotal         float64  `json:"duration_total"`
+	DurationChecks        *float64 `json:"duration_checks,omitempty"`
+	DurationWAF           *float64 `json:"duration_waf,omitempty"`
+	DurationUpstreamTotal *float64 `json:"duration_upstream_total,omitempty"`
 }
 
 // RProxyLine is rproxy's short line in the request log about one request. The