Fix CertFP channel join timing

bot/bot.go

@@ -41,6 +41,8 @@ type Bot struct {
 	warmupUntil    map[string]time.Time
 }
 
+const certFPInitialJoinDelay = 2 * time.Second
+
 func New(cfg Config, db *storage.DB, plugins []Plugin, log *zap.Logger) *Bot {
 	return NewWithStats(cfg, db, plugins, log, NewStats())
 }
@@ -293,9 +295,36 @@ func (b *Bot) connect(ctx context.Context) error {
 			if b.shouldUseNickServFallback() {
 				go b.nickServFallback(c, actualNick)
 			}
-			for _, ch := range b.Config.Channels {
-				b.markChannelWarmup(ch)
-				c.Write("JOIN " + ch)
+			joinChannels := func() {
+				// A delayed callback must not send a JOIN on a connection that
+				// has already been replaced by a reconnect.
+				b.mu.RLock()
+				currentClient := b.client
+				b.mu.RUnlock()
+				if currentClient != c {
+					return
+				}
+				for _, ch := range b.Config.Channels {
+					b.markChannelWarmup(ch)
+					c.Write("JOIN " + ch)
+				}
+			}
+			if shouldDelayCertFPJoin(b.Config.Server, mechanism, capState) {
+				b.Log.Info("delaying initial channel joins for CertFP identification",
+					zap.String("network", b.Config.NetworkName),
+					zap.Duration("delay", certFPInitialJoinDelay),
+				)
+				timer := time.NewTimer(certFPInitialJoinDelay)
+				go func() {
+					defer timer.Stop()
+					select {
+					case <-timer.C:
+						joinChannels()
+					case <-ctx.Done():
+					}
+				}()
+			} else {
+				joinChannels()
 			}
 		}
 		if m.Command == "NOTICE" && capState.certFPEnroll && capState.enrollSent && m.Prefix != nil && strings.EqualFold(m.Prefix.Name, capState.nickServName) {
@@ -350,6 +379,13 @@ func (b *Bot) connect(ctx context.Context) error {
 	}
 }
 
+func shouldDelayCertFPJoin(server ServerConfig, mechanism string, state *capNegotiation) bool {
+	return strings.TrimSpace(server.ClientCert) != "" &&
+		strings.EqualFold(strings.TrimSpace(mechanism), "EXTERNAL") &&
+		state != nil &&
+		!state.saslSucceeded
+}
+
 func (b *Bot) trackOwnChannelMembership(currentNick string, message *irc.Message) {
 	if b.networkStats == nil || message == nil || message.Prefix == nil {
 		return

bot/join_test.go

@@ -0,0 +1,33 @@
+package bot
+
+import "testing"
+
+func TestShouldDelayCertFPJoinOnlyForUnconfirmedExternalAuth(t *testing.T) {
+	server := ServerConfig{ClientCert: "/etc/gobot/oftc.pem"}
+
+	tests := []struct {
+		name       string
+		clientCert bool
+		mechanism  string
+		state      *capNegotiation
+		want       bool
+	}{
+		{name: "OFTC CertFP without SASL confirmation", clientCert: true, mechanism: "EXTERNAL", state: &capNegotiation{}, want: true},
+		{name: "successful SASL EXTERNAL", clientCert: true, mechanism: "EXTERNAL", state: &capNegotiation{saslSucceeded: true}, want: false},
+		{name: "password SASL", clientCert: true, mechanism: "PLAIN", state: &capNegotiation{}, want: false},
+		{name: "no client certificate", mechanism: "EXTERNAL", state: &capNegotiation{}, want: false},
+		{name: "missing negotiation state", clientCert: true, mechanism: "EXTERNAL", state: nil, want: false},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			candidate := ServerConfig{}
+			if test.clientCert {
+				candidate = server
+			}
+			if got := shouldDelayCertFPJoin(candidate, test.mechanism, test.state); got != test.want {
+				t.Fatalf("shouldDelayCertFPJoin() = %v, want %v", got, test.want)
+			}
+		})
+	}
+}

docs/nickserv-sasl.md

@@ -183,5 +183,13 @@ For the final passwordless mode, the server must advertise SASL and the
 `EXTERNAL` mechanism. All DNS backends behind a shared IRC hostname should
 expose the same capability set.
 
+Some networks, including OFTC, use the client certificate for TLS CertFP
+identification but do not advertise SASL `EXTERNAL`. GoBot still presents the
+configured certificate during the TLS handshake. When SASL `EXTERNAL` is not
+confirmed, GoBot waits two seconds before its initial channel joins so services
+can apply the account identification and cloak first. The warning that the
+configured SASL mechanism was not advertised is expected for this network;
+it does not mean that the TLS certificate failed.
+
 If a network renames the bot to Guest..., review the optional nickserv_fallback
 and nickserv_ghost identity settings.