Files
smallwebwaf/internal/proxy/biased.go
T
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Blocklists and an AS percentage file fetched by URL (closes #29)
SWWAF_BLOCKLIST_URLS names lists of addresses and netblocks, fetched every
SWWAF_BLOCKLIST_REFRESH (24h, never under 1h); an IPv4-mapped line stands
for its IPv4 address or netblock. reputation.json keeps each list's last
try, failed or not, even one cut off by a stop, which a restart waits on
as a running instance does, and its last good copy, whole, used while a
fetch fails. SWWAF_BLOCKLIST_ACTION denies, limits or only logs a listed
client; the log line names the lists, each raises reputation_hit, and a
failed fetch raises source_failure. SWWAF_ASN_LIMIT_PERCENT_URL is fetched
the same way and counts as SWWAF_ASN_LIMIT_PERCENT does, the lower winning.

Judgement call: a failed fetch is retried after the refresh, not sooner.
Not done: ban notes do not name the lists yet.

Model: opus-5-5
2026-10-07 16:51:48 +00:00

112 lines
4.0 KiB
Go

package proxy
import (
"sneak.berlin/go/smallwebwaf/internal/config"
)
// whole is the percentage of each limit a client gets when no biased
// threshold lowers its limits.
const whole = 100
// percentage is a client's limit percentage for the rate limits or for
// the byte limits, as the biased thresholds give it, and the setting that
// gave it: "" with whole when none lowers that kind of limit.
type percentage struct {
percent int64
setting string
}
// biasedThresholdsSet reports whether a biased threshold can lower a
// client's limits: one of its lists is not empty,
// SWWAF_UNKNOWN_LIMIT_PERCENT is below 100, or SWWAF_ASN_LIMIT_PERCENT_URL
// is set. The client's lookup is then needed before its request goes on.
func biasedThresholdsSet(cfg *config.Config) bool {
return len(cfg.ASNLimitPercent) > 0 || len(cfg.CountryLimitPercent) > 0 ||
len(cfg.ASNBytesPercent) > 0 || len(cfg.CountryBytesPercent) > 0 ||
cfg.UnknownLimitPercent < whole || cfg.ASNLimitPercentURL != ""
}
// limitPercentages returns the client's limit percentages, for the rate
// limits and for the byte limits, by its AS number and country as looked
// up, each "" when unknown, and the blocklists that list it. Each is the
// lowest of those the settings give it, the first of them in the order
// below when several are lowest: the percentage SWWAF_ASN_LIMIT_PERCENT
// gives its AS number, the one the file SWWAF_ASN_LIMIT_PERCENT_URL names
// gives it, the one SWWAF_COUNTRY_LIMIT_PERCENT gives its country, for a
// client without a country, SWWAF_UNKNOWN_LIMIT_PERCENT, and for a client
// a blocklist lists, the percentage of SWWAF_BLOCKLIST_ACTION while it is
// limit. For the byte limits, SWWAF_ASN_BYTES_PERCENT and
// SWWAF_COUNTRY_BYTES_PERCENT take the place of the first three for an AS
// number or a country they list.
func (rq *request) limitPercentages() (percentage, percentage) {
cfg := rq.h.config
asn, country := rq.line.ASN, rq.line.Country
unknown := percentage{percent: whole}
if country == "" {
unknown = percentage{cfg.UnknownLimitPercent, "SWWAF_UNKNOWN_LIMIT_PERCENT"}
}
fetched := percentage{percent: whole}
if percent, listed := rq.h.lists.ASNLimitPercent(asn); listed {
fetched = percentage{percent, "SWWAF_ASN_LIMIT_PERCENT_URL"}
}
listed := percentage{percent: whole}
if len(rq.line.Reputation) > 0 && cfg.BlocklistAction == "limit" {
listed = percentage{cfg.BlocklistLimitPercent, "SWWAF_BLOCKLIST_ACTION"}
}
asnRequests := lowest(given(cfg.ASNLimitPercent, asn, "SWWAF_ASN_LIMIT_PERCENT"),
fetched)
countryRequests := given(cfg.CountryLimitPercent, country,
"SWWAF_COUNTRY_LIMIT_PERCENT")
asnBytes, countryBytes := asnRequests, countryRequests
if _, listed := cfg.ASNBytesPercent[asn]; listed {
asnBytes = given(cfg.ASNBytesPercent, asn, "SWWAF_ASN_BYTES_PERCENT")
}
if _, listed := cfg.CountryBytesPercent[country]; listed {
countryBytes = given(cfg.CountryBytesPercent, country, "SWWAF_COUNTRY_BYTES_PERCENT")
}
return lowest(asnRequests, countryRequests, unknown, listed),
lowest(asnBytes, countryBytes, unknown, listed)
}
// given returns the percentage percents, the setting named setting, gives
// code, an AS number or a country, or whole when it does not list code.
func given(percents map[string]int64, code, setting string) percentage {
percent, listed := percents[code]
if !listed {
return percentage{percent: whole}
}
return percentage{percent, setting}
}
// lowest returns the lowest of percentages below whole, the first of them
// when several are lowest, or whole when none is below it.
func lowest(percentages ...percentage) percentage {
low := percentage{percent: whole}
for _, p := range percentages {
if p.percent < low.percent {
low = p
}
}
return low
}
// logged returns p as the log line and the notes of a ban give it: its
// percent and setting, or nil and "" for whole, which they leave out.
func (p percentage) logged() (*int64, string) {
if p.percent == whole {
return nil, ""
}
return &p.percent, p.setting
}