fix(mtproto): sync accept TDLib reconnect service parity

internal/mtprotoedge/auth_key_switch_test.go

@@ -15,7 +15,7 @@ func TestEncryptedConnectionSwitchesAuthKeyEvenWhenSessionIDIsReused(t *testing.
 	_, authB, cipherB := dialHandshake(t, addr, dc, pub)
 	msgID := proto.NewMessageIDGen(time.Now)
 
-	sendEncrypted(t, connA, cipherA, authA, msgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
+	sendEncryptedWithSeq(t, connA, cipherA, authA, msgID.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 1})
 	for range 3 { // new_session_created + pong + msgs_ack; leave no A-key frame on the socket.
 		readServerMessage(t, connA, cipherA, authA.AuthKey)
 	}

internal/mtprotoedge/encrypted.go

@@ -1481,15 +1481,15 @@ func validateClientEnvelope(now time.Time, msgID int64, seqNo int32, typeID uint
 	if msgTime.After(now.Add(30 * time.Second)) {
 		return badMsgIDTooHigh
 	}
-	if clientMessageAllowsEitherSeqParity(typeID) {
+	switch clientMessageContentPolicyFor(typeID) {
-		return 0
+	case clientMessageContentRequired:
-	}
-	if clientMessageNeedsAck(typeID) {
 		if seqNo%2 == 0 {
 			return badMsgSeqNotOdd
 		}
-	} else if seqNo%2 != 0 {
+	case clientMessageContentForbidden:
-		return badMsgSeqNotEven
+		if seqNo%2 != 0 {
+			return badMsgSeqNotEven
+		}
 	}
 	return 0
 }
@@ -1498,48 +1498,68 @@ func validateClientContainerEnvelope(msgID int64, seqNo int32, typeID uint32) in
 	if !validClientMessageIDBits(msgID) {
 		return badMsgIDInvalidBits
 	}
-	if clientMessageAllowsEitherSeqParity(typeID) {
+	switch clientMessageContentPolicyFor(typeID) {
-		return 0
+	case clientMessageContentRequired:
-	}
-	if clientMessageNeedsAck(typeID) {
 		if seqNo%2 == 0 {
 			return badMsgSeqNotOdd
 		}
-	} else if seqNo%2 != 0 {
+	case clientMessageContentForbidden:
-		return badMsgSeqNotEven
+		if seqNo%2 != 0 {
+			return badMsgSeqNotEven
+		}
 	}
 	return 0
 }
 
-func clientMessageAllowsEitherSeqParity(typeID uint32) bool {
+type clientMessageContentPolicy uint8
-	switch typeID {
-	case mt.PingDelayDisconnectRequestTypeID,
-		// get_future_salts 的 seqno 奇偶在客户端间不一致：部分客户端按内容消息发奇数，
-		// gotd 按服务消息发偶数。两者都合法（官方服务器都接受），故不在此卡奇偶，避免
-		// 误判 bad_msg 触发客户端重连风暴。ack/content 行为仍由 clientMessageNeedsAck 决定。
-		mt.GetFutureSaltsRequestTypeID:
-		return true
-	default:
-		return false
-	}
-}
 
-func clientMessageNeedsAck(typeID uint32) bool {
+const (
+	clientMessageContentRequired clientMessageContentPolicy = iota + 1
+	clientMessageContentForbidden
+	clientMessageContentOptional
+)
+
+// clientMessageContentPolicyFor classifies the client envelope, not merely the
+// constructor's usual sending convention. MTProto requires API RPCs to be
+// content-related and requires containers/acknowledgements to be irrelevant,
+// but clients may mark the other service constructors as either. TDLib uses
+// even sequence numbers for its reconnect state/resend/cancel service batch,
+// while gotd and DrKLO use odd sequence numbers for some of the same requests.
+func clientMessageContentPolicyFor(typeID uint32) clientMessageContentPolicy {
 	switch typeID {
 	case proto.MessageContainerTypeID,
 		mt.MsgsAckTypeID,
+		mt.MsgCopyTypeID:
+		return clientMessageContentForbidden
+	case mt.PingRequestTypeID,
 		mt.PingDelayDisconnectRequestTypeID,
-		mt.DestroySessionRequestTypeID,
+		mt.GetFutureSaltsRequestTypeID,
-		mt.HTTPWaitRequestTypeID,
+		mt.MsgsStateReqTypeID,
-		mt.BadMsgNotificationTypeID,
+		mt.MsgResendReqTypeID,
-		mt.BadServerSaltTypeID,
 		mt.MsgsAllInfoTypeID,
 		mt.MsgsStateInfoTypeID,
+		mt.DestroySessionRequestTypeID,
+		mt.HTTPWaitRequestTypeID,
+		mt.RPCDropAnswerRequestTypeID,
+		mt.BadMsgNotificationTypeID,
+		mt.BadServerSaltTypeID,
 		mt.MsgDetailedInfoTypeID,
-		mt.MsgNewDetailedInfoTypeID:
+		mt.MsgNewDetailedInfoTypeID,
-		return false
+		destroyAuthKeyRequestTypeID:
+		return clientMessageContentOptional
 	default:
+		return clientMessageContentRequired
+	}
+}
+
+func clientMessageIsContentRelated(typeID uint32, seqNo int32) bool {
+	switch clientMessageContentPolicyFor(typeID) {
+	case clientMessageContentRequired:
 		return true
+	case clientMessageContentOptional:
+		return seqNo%2 != 0
+	default:
+		return false
 	}
 }
 

internal/mtprotoedge/encrypted_test.go

@@ -69,6 +69,72 @@ func (h *durableDestroyLayerRPC) deletion() ([8]byte, int64) {
 	return h.authKeyID, h.sessionID
 }
 
+func TestClientMessageContentPolicy(t *testing.T) {
+	tests := []struct {
+		name   string
+		typeID uint32
+		want   clientMessageContentPolicy
+	}{
+		{name: "api_rpc", typeID: tg.HelpGetConfigRequestTypeID, want: clientMessageContentRequired},
+		{name: "container", typeID: proto.MessageContainerTypeID, want: clientMessageContentForbidden},
+		{name: "msgs_ack", typeID: mt.MsgsAckTypeID, want: clientMessageContentForbidden},
+		{name: "msg_copy", typeID: mt.MsgCopyTypeID, want: clientMessageContentForbidden},
+		{name: "bad_msg_notification", typeID: mt.BadMsgNotificationTypeID, want: clientMessageContentOptional},
+		{name: "bad_server_salt", typeID: mt.BadServerSaltTypeID, want: clientMessageContentOptional},
+		{name: "msg_detailed_info", typeID: mt.MsgDetailedInfoTypeID, want: clientMessageContentOptional},
+		{name: "msg_new_detailed_info", typeID: mt.MsgNewDetailedInfoTypeID, want: clientMessageContentOptional},
+		{name: "ping", typeID: mt.PingRequestTypeID, want: clientMessageContentOptional},
+		{name: "ping_delay_disconnect", typeID: mt.PingDelayDisconnectRequestTypeID, want: clientMessageContentOptional},
+		{name: "get_future_salts", typeID: mt.GetFutureSaltsRequestTypeID, want: clientMessageContentOptional},
+		{name: "msgs_state_req", typeID: mt.MsgsStateReqTypeID, want: clientMessageContentOptional},
+		{name: "msg_resend_req", typeID: mt.MsgResendReqTypeID, want: clientMessageContentOptional},
+		{name: "msgs_all_info", typeID: mt.MsgsAllInfoTypeID, want: clientMessageContentOptional},
+		{name: "msgs_state_info", typeID: mt.MsgsStateInfoTypeID, want: clientMessageContentOptional},
+		{name: "destroy_session", typeID: mt.DestroySessionRequestTypeID, want: clientMessageContentOptional},
+		{name: "http_wait", typeID: mt.HTTPWaitRequestTypeID, want: clientMessageContentOptional},
+		{name: "rpc_drop_answer", typeID: mt.RPCDropAnswerRequestTypeID, want: clientMessageContentOptional},
+		{name: "destroy_auth_key", typeID: destroyAuthKeyRequestTypeID, want: clientMessageContentOptional},
+	}
+
+	now := time.Now()
+	msgID := proto.NewMessageIDGen(func() time.Time { return now }).New(proto.MessageFromClient)
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := clientMessageContentPolicyFor(test.typeID); got != test.want {
+				t.Fatalf("content policy = %d, want %d", got, test.want)
+			}
+
+			evenCode := validateClientContainerEnvelope(msgID, 8, test.typeID)
+			oddCode := validateClientContainerEnvelope(msgID, 9, test.typeID)
+			directEvenCode := validateClientEnvelope(now, msgID, 8, test.typeID)
+			directOddCode := validateClientEnvelope(now, msgID, 9, test.typeID)
+			if directEvenCode != evenCode || directOddCode != oddCode {
+				t.Fatalf(
+					"top-level/container parity mismatch = top(%d,%d) container(%d,%d)",
+					directEvenCode, directOddCode, evenCode, oddCode,
+				)
+			}
+			switch test.want {
+			case clientMessageContentRequired:
+				if evenCode != badMsgSeqNotOdd || oddCode != 0 {
+					t.Fatalf("required content parity codes = even:%d odd:%d", evenCode, oddCode)
+				}
+			case clientMessageContentForbidden:
+				if evenCode != 0 || oddCode != badMsgSeqNotEven {
+					t.Fatalf("forbidden content parity codes = even:%d odd:%d", evenCode, oddCode)
+				}
+			case clientMessageContentOptional:
+				if evenCode != 0 || oddCode != 0 {
+					t.Fatalf("optional content parity codes = even:%d odd:%d", evenCode, oddCode)
+				}
+				if clientMessageIsContentRelated(test.typeID, 8) || !clientMessageIsContentRelated(test.typeID, 9) {
+					t.Fatal("optional service content bit was not derived from seq_no parity")
+				}
+			}
+		})
+	}
+}
+
 // TestEncryptedPingPong 验证 M2/M4：握手后 client 加密 ping，
 // server 回 new_session_created + pong + msgs_ack。
 func TestEncryptedPingPong(t *testing.T) {
@@ -79,7 +145,7 @@ func TestEncryptedPingPong(t *testing.T) {
 	clientMsgID := proto.NewMessageIDGen(time.Now)
 	const pingID int64 = 0x1234beef
 	pingMsgID := clientMsgID.New(proto.MessageFromClient)
-	sendEncrypted(t, conn, cipher, auth, pingMsgID, &mt.PingRequest{PingID: pingID})
+	sendEncryptedWithSeq(t, conn, cipher, auth, pingMsgID, 1, &mt.PingRequest{PingID: pingID})
 
 	replies := collectReplies(t, conn, cipher, auth.AuthKey, mt.PongTypeID)
 	mustHave(t, replies, mt.NewSessionCreatedTypeID, "new_session_created")
@@ -230,6 +296,55 @@ func TestMsgsStateReq(t *testing.T) {
 	}
 }
 
+// TestTDLibReconnectRecoveryContainerAcceptsEvenServiceMessages reproduces the
+// first container TDLib emits after reopening an authenticated session with
+// unknown queries. All service entries and the outer container use the current
+// even sequence number. Rejecting msgs_state_req as a content-only constructor
+// turns the valid inner message into bad_msg_notification(code=64), after which
+// TDLib closes the session and retries the same container forever.
+func TestTDLibReconnectRecoveryContainerAcceptsEvenServiceMessages(t *testing.T) {
+	const dc = 2
+	addr, pub, _ := startTestServer(t, Options{DC: dc})
+	conn, auth, cipher := dialHandshake(t, addr, dc, pub)
+
+	ids := proto.NewMessageIDGen(time.Now)
+	pendingMsgID := ids.New(proto.MessageFromClient)
+	ackMsgID := ids.New(proto.MessageFromClient)
+	stateMsgID := ids.New(proto.MessageFromClient)
+	pingMsgID := ids.New(proto.MessageFromClient)
+	outerMsgID := ids.New(proto.MessageFromClient)
+	const (
+		pendingSeqNo int32 = 9
+		serviceSeqNo int32 = 10
+	)
+
+	pendingBody := mustEncodeTL(t, &mt.PingRequest{PingID: 0xc01d})
+	ackBody := mustEncodeTL(t, &mt.MsgsAck{MsgIDs: []int64{stateMsgID - 4}})
+	stateBody := mustEncodeTL(t, &mt.MsgsStateReq{MsgIDs: []int64{pendingMsgID, stateMsgID - 4}})
+	pingBody := mustEncodeTL(t, &mt.PingDelayDisconnectRequest{PingID: 0x5eed, DisconnectDelay: 60})
+	container := &proto.MessageContainer{Messages: []proto.Message{
+		{ID: pendingMsgID, SeqNo: int(pendingSeqNo), Bytes: len(pendingBody), Body: pendingBody},
+		{ID: ackMsgID, SeqNo: int(serviceSeqNo), Bytes: len(ackBody), Body: ackBody},
+		{ID: stateMsgID, SeqNo: int(serviceSeqNo), Bytes: len(stateBody), Body: stateBody},
+		{ID: pingMsgID, SeqNo: int(serviceSeqNo), Bytes: len(pingBody), Body: pingBody},
+	}}
+
+	sendEncryptedWithSeq(t, conn, cipher, auth, outerMsgID, serviceSeqNo, container)
+	frames := collectReplyFrames(t, conn, cipher, auth.AuthKey, map[uint32]int{
+		mt.MsgsStateInfoTypeID: 1,
+		mt.PongTypeID:          2,
+	})
+	for _, frame := range frames {
+		if frame.TypeID == mt.BadMsgNotificationTypeID {
+			var bad mt.BadMsgNotification
+			if err := bad.Decode(frame.Plain); err != nil {
+				t.Fatalf("decode bad_msg_notification: %v", err)
+			}
+			t.Fatalf("TDLib reconnect recovery container was rejected: %+v", bad)
+		}
+	}
+}
+
 // TestMsgResendReq 验证 MTProto msg_resend_req 由连接层按状态查询兜底响应，
 // 不会落入业务 RPC fallback。
 func TestMsgResendReq(t *testing.T) {

internal/mtprotoedge/exchange_test.go

@@ -1044,7 +1044,7 @@ func TestReconnectFakeReqPQThenEncryptedFrame(t *testing.T) {
 	cancel()
 
 	msgGen := tgproto.NewMessageIDGen(time.Now)
-	sendEncrypted(t, conn, cipher, auth, msgGen.New(tgproto.MessageFromClient), &mt.PingRequest{PingID: 7})
+	sendEncryptedWithSeq(t, conn, cipher, auth, msgGen.New(tgproto.MessageFromClient), 1, &mt.PingRequest{PingID: 7})
 
 	var resPQFrame bin.Buffer
 	ctx, cancel = context.WithTimeout(context.Background(), 5*time.Second)

internal/mtprotoedge/helpers_test.go

@@ -250,7 +250,7 @@ func encodeClientMessageForTest(t *testing.T, msg bin.Encoder) ([]byte, int32) {
 	if container, ok := msg.(*proto.MessageContainer); ok {
 		return raw, clientContainerSeqNoForTest(container)
 	}
-	if clientMessageNeedsAck(typeID) {
+	if clientMessageContentPolicyFor(typeID) == clientMessageContentRequired {
 		return raw, 1
 	}
 	return raw, 0

internal/mtprotoedge/inbound_preflight.go

@@ -454,7 +454,7 @@ func (s *Server) walkInbound(
 		return &dispatchBadMsgError{msgID: msgID, seqNo: seqNo, code: code}
 	}
 
-	content := clientMessageNeedsAck(typeID)
+	content := clientMessageIsContentRelated(typeID, seqNo)
 	if record, seen := overlay.seenRecord(msgID); seen {
 		if record.seqNo != seqNo || record.content != content {
 			return &dispatchBadMsgError{msgID: msgID, seqNo: seqNo, code: badMsgContainer}

internal/mtprotoedge/layer_seed_test.go

@@ -28,7 +28,7 @@ func TestRegisterSeedsNegotiatedLayerBeforeFirstRPC(t *testing.T) {
 	conn, auth, cipher := dialHandshake(t, addr, 2, pub)
 
 	clientMsgID := proto.NewMessageIDGen(time.Now)
-	sendEncrypted(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 7})
+	sendEncryptedWithSeq(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 7})
 
 	// 等 pong 回来，确保携带注册动作的那一帧已处理完成。
 	gotPong := false

internal/mtprotoedge/outbound_test.go

@@ -544,7 +544,7 @@ func TestOutboundActorSerializesConcurrentSends(t *testing.T) {
 	conn, auth, cipher := dialHandshake(t, addr, dc, pub)
 
 	clientMsgID := proto.NewMessageIDGen(time.Now)
-	sendEncrypted(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
+	sendEncryptedWithSeq(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 1})
 	collectReplies(t, conn, cipher, auth.AuthKey, mt.MsgsAckTypeID)
 	freezeActiveTestSessionProfile(t, srv.Conns(), auth.AuthKey.ID, auth.SessionID, tlprofile.ProfileCanonical)
 	srv.Conns().SetReceivesUpdates(auth.SessionID, true)
@@ -1034,7 +1034,7 @@ func TestOutboundResendAndAckState(t *testing.T) {
 	conn, auth, cipher := dialHandshake(t, addr, dc, pub)
 
 	clientMsgID := proto.NewMessageIDGen(time.Now)
-	sendEncrypted(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
+	sendEncryptedWithSeq(t, conn, cipher, auth, clientMsgID.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 1})
 	collectReplies(t, conn, cipher, auth.AuthKey, mt.MsgsAckTypeID)
 	freezeActiveTestSessionProfile(t, srv.Conns(), auth.AuthKey.ID, auth.SessionID, tlprofile.ProfileCanonical)
 	srv.Conns().SetReceivesUpdates(auth.SessionID, true)

internal/mtprotoedge/session_manager_test.go

@@ -1205,9 +1205,9 @@ func TestSessionManagerPush(t *testing.T) {
 
 	// 各发一个 ping 建立 session，触发注册（并清掉 new_session_created/pong/ack）。
 	msgGen := proto.NewMessageIDGen(time.Now)
-	sendEncrypted(t, conn1, cipher1, auth1, msgGen.New(proto.MessageFromClient), &mt.PingRequest{PingID: 1})
+	sendEncryptedWithSeq(t, conn1, cipher1, auth1, msgGen.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 1})
 	collectReplies(t, conn1, cipher1, auth1.AuthKey, mt.PongTypeID)
-	sendEncrypted(t, conn2, cipher2, auth2, msgGen.New(proto.MessageFromClient), &mt.PingRequest{PingID: 2})
+	sendEncryptedWithSeq(t, conn2, cipher2, auth2, msgGen.New(proto.MessageFromClient), 1, &mt.PingRequest{PingID: 2})
 	collectReplies(t, conn2, cipher2, auth2.AuthKey, mt.PongTypeID)
 
 	if got := srv.Conns().Online(); got != 2 {