Lower limits for listed AS numbers and countries (closes #21)

SWWAF_ASN_LIMIT_PERCENT and SWWAF_COUNTRY_LIMIT_PERCENT give the clients
of the AS numbers and countries they list that percentage of every rate
and byte limit, rounded down; SWWAF_ASN_BYTES_PERCENT and
SWWAF_COUNTRY_BYTES_PERCENT take its place for the byte limits of those
they list; SWWAF_UNKNOWN_LIMIT_PERCENT (100) covers clients without a
country. The lowest applies. While one lowers a limit, a request waits
for its client's lookup, and SWWAF_LOOKUP_SOURCE=off stops the start. Log
lines give limit_percent and bytes_percent with their settings; ban
notes, and so alerts, give the broken limit's.

Judgement call: a client without a country is unknown, whatever its AS number.
Judgement call: bytes_percent and its setting are log fields SPEC does not name.
Rule suppressed: funlen on FromEnvironment, one line per setting.

Model: opus-5-5

internal/proxy/request.go

@@ -56,9 +56,12 @@ type request struct {
 	lookedUp     bool
 	lookupAnswer lookup.Answer
 	// counted is true for a request the rate limits counted, whose bytes
-	// the byte limits count once it has ended.
-	counted bool
-	start   time.Time
+	// the byte limits count once it has ended. limitPercent and
+	// bytesPercent are then its client's limit percentages for the rate
+	// limits and for the byte limits.
+	counted                    bool
+	limitPercent, bytesPercent percentage
+	start                      time.Time
 	// checked is when the checks were done, and upstreamStart when the
 	// request was handed to the app.
 	checked       time.Time
@@ -212,9 +215,10 @@ func (rq *request) check(ctx context.Context) *refusal {
 // them refuses is not counted for the rate limits. Then come the rate
 // limits, unless the client is in SWWAF_RATE_LIMIT_EXEMPT_NETS or the
 // request's path is exempt under SWWAF_RATE_LIMIT_EXEMPT_PATHS, so that
-// every other request is counted, and last the rule files. A request
-// exempt from the rate limits is exempt from the byte limits too. ctx is
-// the request's own context.
+// every other request is counted, each of them by the client's limit
+// percentages, and last the rule files. A request exempt from the rate
+// limits is exempt from the byte limits too. ctx is the request's own
+// context.
 func (rq *request) checkClient(ctx context.Context) string {
 	cfg := rq.h.config
 	if isInside(rq.client, cfg.AllowNets) {
@@ -239,6 +243,12 @@ func (rq *request) checkClient(ctx context.Context) string {
 
 	rq.counted = !isInside(rq.client, cfg.RateLimitExemptNets) &&
 		!pathExempt(rq.in.URL, cfg.RateLimitExemptPaths)
+	if rq.counted {
+		rq.limitPercent, rq.bytesPercent = limitPercentages(cfg, rq.line.ASN, rq.line.Country)
+		rq.line.LimitPercent, rq.line.LimitPercentSetting = rq.limitPercent.logged()
+		rq.line.BytesPercent, rq.line.BytesPercentSetting = rq.bytesPercent.logged()
+	}
+
 	if rq.counted && rq.limitBroken(now) {
 		return requestlog.ActionRateLimited
 	}