Request tags, with refusing and limits per tag (closes #175)

Each request gets tags, logged as `tags`: `asn=`, `country=`, one per `SWW_TAG_LISTS` list holding the client, `crowdsec`, `dnsbl=<zone>`, `abuseipdb` and `exploitsignature`. `SWW_TAG_DENY` refuses by tag and `SWW_TAG_LIMIT_PERCENT` lowers limits by tag. They replace `SWW_ASN_LIMIT_PERCENT`, `SWW_COUNTRY_LIMIT_PERCENT` and `SWW_DENIED_COUNTRIES`, with no aliases. A tag in those settings that nothing configured can give stops the start.

Judgement call: `SWW_ASN_LIMIT_PERCENT_URL` stays, its entries counting like `asn=` tags.
Judgement call: `SWW_TAG_LIMIT_PERCENT` also lowers byte limits, as the settings it replaces did.
Trips a reader: `sww_country_list_refusals_total` now counts only `SWW_EXCLUSIVELY_ALLOWED_COUNTRIES` refusals.

Model: opus-5-5

internal/discriminator/lookup.go

@@ -4,8 +4,10 @@ import (
 	"context"
 	"net/http"
 	"net/netip"
+	"strings"
 	"time"
 
+	"sneak.berlin/go/smallwebwaf/internal/config"
 	"sneak.berlin/go/smallwebwaf/internal/lookup"
 )
 
@@ -19,7 +21,8 @@ const (
 )
 
 // lookUp looks up the client's AS number and country, in the lookup
-// database or through GeoJS, and notes them for the log line, unless
+// database or through GeoJS, and notes them for the log line and as the
+// request's asn= and country= tags, unless
 // SWW_LOOKUP_SOURCE is off or the client is on a private, loopback or
 // link-local address, which no lookup can place. The lookup database
 // answers at once. With GeoJS, while a setting needs the answer, such as a
@@ -47,6 +50,34 @@ func (rq *request) lookUp(ctx context.Context, now time.Time) {
 	rq.line.ASN = rq.lookupAnswer.ASN
 	rq.line.ASName = rq.lookupAnswer.ASName
 	rq.line.Country = rq.lookupAnswer.Country
+
+	if tag := asnTag(rq.line.ASN); tag != "" {
+		rq.addTag(tag)
+	}
+
+	if tag := countryTag(rq.line.Country); tag != "" {
+		rq.addTag(tag)
+	}
+}
+
+// asnTag returns the tag of asn, an AS number as the lookup gives it, such as
+// asn=64496 for AS64496, or "" for no AS number.
+func asnTag(asn string) string {
+	if asn == "" {
+		return ""
+	}
+
+	return config.ASNTagPrefix + strings.TrimPrefix(asn, "AS")
+}
+
+// countryTag returns the tag of country, a code as the lookup gives it, such
+// as country=DE for DE, or "" for no country.
+func countryTag(country string) string {
+	if country == "" {
+		return ""
+	}
+
+	return config.CountryTagPrefix + country
 }
 
 // addLookup adds answer, an answer about a client from the lookup