inbound-antispam-panel: inbound journal milter on port 25

Step 3/12 of docs/plans/inbound-antispam-panel.md. The panel serves a second milter while the inbound relay is on (internal/milter/inbound.go, socket INBOUND_JOURNAL_MILTER_SOCKET, default /run/selfpost/inbound-journal.sock). build/postfix-config.sh puts it last on port 25, after the optional antispam milter, with default_action=accept; postfix-wrapper.sh waits for its socket. At end-of-message it writes one inbound_spam_log row per recipient at an inbound domain - other port-25 recipients (DMARC report addresses) get none - and always accepts. With a filter attached it reads the verdict from X-Rspamd-Action and X-Spamd-Result (action, score, up to six weighted symbols, only what the patterns recognise, 255 bytes); without one those headers are the sender's and are not read. The plan named X-Rspamd-Score, which rspamd does not have. The antispam compose fragment mounts rspamd/milter_headers.conf into the sidecar so that it adds the two headers (checked in rspamd 3.11: both routines exist and remove a sender's own headers of those names). Store: InsertInboundSpam, IsInboundDomain. Checked on the test server, uncommitted tree: go vet ./... ok, go test ./... ok (22 packages), make e2e ok - the relayed message of inbound_relay_delivers_and_refuses has its journal row (accept by selfpost) and the DMARC report sent through the same listener has none. Not yet seen in a real run: a verdict written by rspamd reaching this milter. The e2e stand has no filter, and the test server's only inbound domain has no upstream, so it accepts no mail. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
2026-10-11 22:18:14 +03:00
parent a3cc52d6d4
commit 28ec784ae2
17 changed files with 748 additions and 31 deletions
@@ -0,0 +1,224 @@
+package milter
+
+import (
+	"errors"
+	"net"
+	"strings"
+	"testing"
+
+	"github.com/emersion/go-milter"
+
+	"github.com/mixeme/selfpost/internal/store"
+)
+
+// fakeInbound is the journal and the inbound-domain list of one test.
+type fakeInbound struct {
+	domains   map[string]bool
+	rows      []store.InboundSpamEntry
+	insertErr error
+	lookupErr error
+}
+
+func (f *fakeInbound) InsertInboundSpam(e store.InboundSpamEntry) error {
+	if f.insertErr != nil {
+		return f.insertErr
+	}
+	f.rows = append(f.rows, e)
+	return nil
+}
+
+func (f *fakeInbound) IsInboundDomain(name string) (bool, error) {
+	if f.lookupErr != nil {
+		return false, f.lookupErr
+	}
+	return f.domains[name], nil
+}
+
+// A header of the kind the documented rspamd sidecar adds.
+const spamdResult = "default: False [7.20 / 15.00];\n\tBAYES_SPAM(5.10)[100.00%];\n\tMIME_GOOD(-0.10)[text/plain];\n\tARC_NA(0.00)[];\n\tRCVD_COUNT_ZERO(0.00)[0];\n\tR_DKIM_NA(2.20)[]"
+
+// message replays one message through s: envelope, headers in order, end.
+func message(t *testing.T, s *inboundSession, from string, rcpts []string, headers [][2]string) milter.Response {
+	t.Helper()
+	if _, err := s.MailFrom(from, mods(nil)); err != nil {
+		t.Fatalf("MailFrom: %v", err)
+	}
+	for _, r := range rcpts {
+		if _, err := s.RcptTo(r, mods(nil)); err != nil {
+			t.Fatalf("RcptTo: %v", err)
+		}
+	}
+	for _, h := range headers {
+		if _, err := s.Header(h[0], h[1], mods(nil)); err != nil {
+			t.Fatalf("Header: %v", err)
+		}
+	}
+	resp, err := s.Body(mods(map[string]string{"i": "ABC123"}))
+	if err != nil {
+		t.Fatalf("Body: %v", err)
+	}
+	return resp
+}
+
+func inboundSessionFor(t *testing.T, rec InboundStore, filter bool) *inboundSession {
+	t.Helper()
+	s := &inboundSession{rec: rec, filter: filter}
+	if _, err := s.Connect("mx.example.net", "tcp4", 0, net.ParseIP("203.0.113.7"), mods(nil)); err != nil {
+		t.Fatalf("Connect: %v", err)
+	}
+	return s
+}
+
+// With no filter attached an accepted message is a plain row, one per
+// recipient, decided by nobody.
+func TestInboundRecordsAcceptedMessage(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, false)
+	resp := message(t, s, "<sender@example.net> SIZE=1200",
+		[]string{"<a@in.example.com>", "b@IN.example.com"},
+		[][2]string{{"Subject", "=?utf-8?Q?Sch=C3=B6n?="}})
+	if resp != milter.RespAccept {
+		t.Errorf("end-of-message response = %v, want accept", resp)
+	}
+	if len(rec.rows) != 2 {
+		t.Fatalf("rows = %+v, want one per recipient", rec.rows)
+	}
+	want := store.InboundSpamEntry{
+		InboundDomain: "in.example.com", ClientIP: "203.0.113.7",
+		From: "sender@example.net", To: "a@in.example.com", Subject: "Schön",
+		Decision: store.SpamDecisionAccept, Engine: store.SpamEngineSelfPost,
+	}
+	if rec.rows[0] != want {
+		t.Errorf("row = %+v\nwant  %+v", rec.rows[0], want)
+	}
+	if rec.rows[1].To != "b@IN.example.com" || rec.rows[1].InboundDomain != "in.example.com" {
+		t.Errorf("second row = %+v", rec.rows[1])
+	}
+}
+
+// Port 25 also takes DMARC reports for the server's own name. They are not
+// the relay's mail and the journal says nothing about them.
+func TestInboundSkipsRecipientsOutsideInboundDomains(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, false)
+	message(t, s, "noreply-dmarc@google.com",
+		[]string{"dmarc-example.com@mail.example.org", "a@in.example.com"}, nil)
+	if len(rec.rows) != 1 || rec.rows[0].To != "a@in.example.com" {
+		t.Errorf("rows = %+v, want the inbound recipient alone", rec.rows)
+	}
+}
+
+// With the filter attached its verdict headers become the engine and detail.
+func TestInboundReadsTheFiltersVerdict(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, true)
+	message(t, s, "sender@example.net", []string{"a@in.example.com"}, [][2]string{
+		{"Subject", "Cheap pills"},
+		{"X-Rspamd-Action", "add header"},
+		{"X-Spamd-Result", spamdResult},
+	})
+	if len(rec.rows) != 1 {
+		t.Fatalf("rows = %+v", rec.rows)
+	}
+	got := rec.rows[0]
+	if got.Engine != store.SpamEngineRspamd || got.Decision != store.SpamDecisionAccept {
+		t.Errorf("engine %q, decision %q", got.Engine, got.Decision)
+	}
+	if want := "add header, score 7.20 / 15.00; BAYES_SPAM(5.10) MIME_GOOD(-0.10) R_DKIM_NA(2.20)"; got.Detail != want {
+		t.Errorf("detail = %q\nwant     %q", got.Detail, want)
+	}
+}
+
+func TestInboundQuarantineAction(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, true)
+	message(t, s, "sender@example.net", []string{"a@in.example.com"},
+		[][2]string{{"x-rspamd-action", "quarantine"}})
+	if len(rec.rows) != 1 || rec.rows[0].Decision != store.SpamDecisionQuarantine || rec.rows[0].Detail != "quarantine" {
+		t.Errorf("rows = %+v", rec.rows)
+	}
+}
+
+// Without a filter in front, a verdict header is the sender's own writing.
+func TestInboundIgnoresVerdictHeadersWithoutAFilter(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, false)
+	message(t, s, "sender@example.net", []string{"a@in.example.com"}, [][2]string{
+		{"X-Rspamd-Action", "no action"},
+		{"X-Spamd-Result", spamdResult},
+	})
+	if len(rec.rows) != 1 || rec.rows[0].Engine != store.SpamEngineSelfPost || rec.rows[0].Detail != "" {
+		t.Errorf("rows = %+v", rec.rows)
+	}
+}
+
+// The filter is attached fail-open, so with it down the headers are again the
+// sender's: nothing of them reaches the journal except through the patterns.
+func TestRspamdVerdictKeepsOnlyWhatItRecognises(t *testing.T) {
+	action, detail := rspamdVerdict("<script>alert(1)</script>", "default: False [1 / 15]; <b>HTML</b> lower_case(9.9) \x1b[31m")
+	if action != "" {
+		t.Errorf("action = %q, want it dropped", action)
+	}
+	if detail != "score 1 / 15" {
+		t.Errorf("detail = %q", detail)
+	}
+
+	var many strings.Builder
+	for i := 0; i < 400; i++ {
+		many.WriteString("SYMBOL_WITH_A_LONG_NAME_" + strings.Repeat("X", 30) + "(1.00)[];")
+	}
+	if _, detail := rspamdVerdict("reject", many.String()); len(detail) > verdictMaxBytes || strings.Count(detail, "(") > verdictMaxSymbols {
+		t.Errorf("detail of %d bytes with %d symbols", len(detail), strings.Count(detail, "("))
+	}
+	if action, _ := rspamdVerdict(strings.Repeat("a", 33), ""); action != "" {
+		t.Errorf("an action of 33 letters was kept")
+	}
+}
+
+// A second message on the same connection starts clean.
+func TestInboundResetsBetweenMessages(t *testing.T) {
+	rec := &fakeInbound{domains: map[string]bool{"in.example.com": true}}
+	s := inboundSessionFor(t, rec, true)
+	message(t, s, "one@example.net", []string{"a@in.example.com"}, [][2]string{
+		{"Subject", "First"}, {"X-Rspamd-Action", "add header"},
+	})
+	message(t, s, "two@example.net", []string{"b@in.example.com"}, nil)
+	if len(rec.rows) != 2 {
+		t.Fatalf("rows = %+v", rec.rows)
+	}
+	want := store.InboundSpamEntry{
+		InboundDomain: "in.example.com", ClientIP: "203.0.113.7",
+		From: "two@example.net", To: "b@in.example.com",
+		Decision: store.SpamDecisionAccept, Engine: store.SpamEngineSelfPost,
+	}
+	if rec.rows[1] != want {
+		t.Errorf("second row = %+v\nwant         %+v", rec.rows[1], want)
+	}
+
+	// An aborted transaction leaves nothing behind for the next one either.
+	if _, err := s.MailFrom("three@example.net", mods(nil)); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := s.RcptTo("c@in.example.com", mods(nil)); err != nil {
+		t.Fatal(err)
+	}
+	if err := s.Abort(mods(nil)); err != nil {
+		t.Fatal(err)
+	}
+	if len(rec.rows) != 2 || len(s.rcpts) != 0 {
+		t.Errorf("after an abort: rows %d, pending recipients %v", len(rec.rows), s.rcpts)
+	}
+}
+
+// The journal failing is never the mail's problem.
+func TestInboundAcceptsWhenTheStoreFails(t *testing.T) {
+	for name, rec := range map[string]*fakeInbound{
+		"insert": {domains: map[string]bool{"in.example.com": true}, insertErr: errors.New("boom")},
+		"lookup": {lookupErr: errors.New("boom")},
+	} {
+		s := inboundSessionFor(t, rec, false)
+		if resp := message(t, s, "sender@example.net", []string{"a@in.example.com"}, nil); resp != milter.RespAccept {
+			t.Errorf("%s failure: response = %v, want accept", name, resp)
+		}
+	}
+}