mixeme
96 lines
3.3 KiB
Go
96 lines
3.3 KiB
Go
package milter
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import (
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"log"
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"time"
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"github.com/mixeme/selfpost/internal/store"
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)
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// overLimit reports whether the message currently being received should be
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// refused under a level-2 differentiated limit (guide § Rate limiting). It
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// checks the domain-level and application-level limits in turn; either being
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// exceeded is enough to refuse.
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//
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// It is deliberately fail-open: any store error, or the absence of a usable
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// limit, is treated as "not over limit" so a malfunction of the level-2
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// limiter can never block mail — Postfix's level-1 anvil limit
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// (architecture.md § Mail path) remains the backstop, and it does not depend
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// on this milter at all. Only a clean count at or above a configured ceiling
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// returns true.
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//
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// A message that passes reserves a slot per applicable limit, released once it
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// reaches the send log (or is abandoned) — see inflight for why the stored
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// count alone is not enough.
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func (s *session) overLimit() bool {
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if s.clientIP == "" {
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return false // no client IP to key on; level-2 does not apply
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}
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checks := []struct{ scope, ref string }{
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{store.RateLimitScopeDomain, domainOf(s.from)},
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{store.RateLimitScopeApp, s.login},
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}
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var taken []*reservation
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for _, c := range checks {
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if c.ref == "" {
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continue
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}
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rl, ok, err := s.rec.RateLimit(c.scope, c.ref)
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if err != nil {
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log.Printf("journal-milter: rate-limit lookup %s %q: %v (fail-open)", c.scope, c.ref, err)
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continue
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}
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// No limit configured, an inert draft, or a client IP outside the
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// registered set: the differentiated limit does not apply here.
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if !ok || !rl.Active() || !rl.AllowsIP(s.clientIP) {
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continue
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}
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since := time.Now().Add(-time.Duration(rl.WindowSeconds) * time.Second)
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n, err := s.rec.CountMessages(c.scope, c.ref, since)
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if err != nil {
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log.Printf("journal-milter: rate-limit count %s %q: %v (fail-open)", c.scope, c.ref, err)
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continue
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}
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key := c.scope + "|" + c.ref
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n += s.flight.count(key, since)
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if n >= int64(rl.MaxMessages) {
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log.Printf("journal-milter: %s %q over limit: %d/%d in %ds from %s — refusing 4xx",
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c.scope, c.ref, n, rl.MaxMessages, rl.WindowSeconds, s.clientIP)
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// The message is refused, so the slots claimed for the limits
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// checked before this one must not stay claimed.
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for _, r := range taken {
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s.flight.release(r)
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}
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return true
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}
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taken = append(taken, s.flight.reserve(key))
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}
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s.reserved = append(s.reserved, taken...)
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return false
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}
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// releaseReservations gives back every slot this message holds. It runs once
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// the message is in the send log (where the stored count sees it), and whenever
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// the transaction ends without getting there.
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func (s *session) releaseReservations() {
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for _, r := range s.reserved {
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s.flight.release(r)
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}
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s.reserved = nil
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}
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// recordRejected writes a send-log row for a message refused by a level-2
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// limit (guide § Rate limiting — refusals are recorded too), so the rejection
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// shows up in the monitoring screen. Only MAIL-stage fields are known; the
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// write is best-effort and never affects the response.
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func (s *session) recordRejected() {
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err := s.rec.InsertRejected(store.SendLogEntry{
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Domain: domainOf(s.from),
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AppLogin: s.login,
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From: s.from,
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})
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if err != nil {
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log.Printf("journal-milter: record rejected %s: %v", s.from, err)
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}
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}
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