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/requestlog/requestlog.go

@@ -1,5 +1,5 @@
 // Package requestlog writes the lines sww prints on stdout: one
-// JSON object per request, two from discriminator and a short one from rproxy,
+// JSON object per request, two from waf and a short one from rproxy,
 // marked "type":"request", and the process's own messages as JSON lines marked
 // "type":"process".
 package requestlog
@@ -14,9 +14,9 @@ import (
 	"sneak.berlin/go/smallwebwaf/internal/ratelimit"
 )
 
-// The action a request line names: what discriminator did with the request.
+// The action a request line names: what waf did with the request.
 const (
-	// ActionForward is a request discriminator allowed, which rproxy passes to
+	// ActionForward is a request waf allowed, which rproxy passes to
 	// the app.
 	ActionForward = "forward"
 
@@ -55,7 +55,7 @@ const (
 	// ActionCountryDenied is a request refused because its client's country
 	// is not in SWW_EXCLUSIVELY_ALLOWED_COUNTRIES.
 	ActionCountryDenied = "country_denied"
-	// ActionOwnEndpoint is a request discriminator answered at one of its own
+	// ActionOwnEndpoint is a request waf answered at one of its own
 	// endpoints, or a question about a path under /_sww/.
 	ActionOwnEndpoint = "own_endpoint"
 )
@@ -69,14 +69,14 @@ const OffenceLimit = "limit"
 // that broke the error burst.
 const LimitHitMinuteRefusals = "minute_refusals"
 
-// The discriminator_line a request line names, which says which of
-// discriminator's two lines about a question it is.
+// The waf_line a request line names, which says which of
+// waf's two lines about a question it is.
 const (
-	// DiscriminatorLineDecision is discriminator's line at its decision.
-	DiscriminatorLineDecision = "decision"
-	// DiscriminatorLineReport is discriminator's line when rproxy's report
+	// WAFLineDecision is waf's line at its decision.
+	WAFLineDecision = "decision"
+	// WAFLineReport is waf's line when rproxy's report
 	// comes, with the decision's fields and the report's together.
-	DiscriminatorLineReport = "report"
+	WAFLineReport = "report"
 )
 
 // timeLayout is RFC 3339 with milliseconds.
@@ -89,9 +89,9 @@ const timeLayout = "2006-01-02T15:04:05.000Z07:00"
 //nolint:tagliatelle // docs/request-log.md names the fields in snake_case
 type Line struct {
 	Type string `json:"type"`
-	// DiscriminatorLine is DiscriminatorLineDecision or DiscriminatorLineReport
-	// on discriminator's two lines about a question.
-	DiscriminatorLine string `json:"discriminator_line,omitempty"`
+	// WAFLine is WAFLineDecision or WAFLineReport
+	// on waf's two lines about a question.
+	WAFLine string `json:"waf_line,omitempty"`
 
 	// The standard web log fields. Scheme is how the client reached rproxy, or
 	// the trusted proxy in front of it.
@@ -111,7 +111,7 @@ type Line struct {
 	UserAgent     string `json:"user_agent"`
 
 	// Request detail. RequestID is the id rproxy made for the request, or for a
-	// request to discriminator's own endpoints a new one. ForwardedFor is the
+	// request to waf'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.
@@ -131,7 +131,7 @@ type Line struct {
 	HasAuthorization bool              `json:"has_authorization,omitempty"`
 	HasCookie        bool              `json:"has_cookie,omitempty"`
 
-	// Response detail, of discriminator's own answer. Aborted is true when
+	// Response detail, of waf'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"`
 	Aborted             bool   `json:"aborted,omitempty"`
@@ -142,7 +142,7 @@ type Line struct {
 	// taken with a request it would have refused: ActionClientDenied,
 	// ActionTemporarilyBanned, ActionPermanentlyBanned, ActionCountryDenied,
 	// ActionClientIsRateLimited, ActionBlockedByBlockRule,
-	// ActionBlockedByCoreRuleSet, or, in discriminator,
+	// ActionBlockedByCoreRuleSet, or, in waf,
 	// ActionRequestHeaderTooLarge for the header limits.
 	WouldAction string `json:"would_action,omitempty"`
 	// Heuristic is the name of the heuristic that refused the request, in
@@ -151,7 +151,7 @@ type Line struct {
 	Heuristic        string         `json:"heuristic,omitempty"`
 	HeuristicFigures map[string]any `json:"heuristic_figures,omitempty"`
 	// AfterAnswerHeuristic and AfterAnswerHeuristicFigures are the same for
-	// the heuristic that banned the client after discriminator answered the
+	// the heuristic that banned the client after waf answered the
 	// request.
 	AfterAnswerHeuristic        string         `json:"after_answer_heuristic,omitempty"`
 	AfterAnswerHeuristicFigures map[string]any `json:"after_answer_heuristic_figures,omitempty"` //nolint:lll // a struct tag cannot be split
@@ -231,7 +231,7 @@ type RProxyLine struct {
 	// sooner. DurationResponseMS runs from then until the answer ends.
 	DurationRequestMS  float64 `json:"duration_request_ms"`
 	DurationResponseMS float64 `json:"duration_response_ms"`
-	// Disposition is the valid disposition discriminator answered or, while
+	// Disposition is the valid disposition waf answered or, while
 	// DefaultDisposition is true, the value of SWRP_DEFAULT_DISPOSITION. It is ""
 	// when neither gave one.
 	Disposition        string `json:"disposition,omitempty"`