如何在protobuf.net中反序列化UDPTunnel

我正在Unity3d (c#脚本)中做一个voip客户端代码，现在我能够成功连接到任何一个mumble公共服务器。但是当我试图反序列化UDP隧道时，我得到了很多例外，包括"无效的wiretype"，"数字溢出"，"无效字段"，"endofstream"，"错误的组结束了"和bla bla……

var udpTunnel = Serializer.DeserializeWithLengthPrefix<UDPTunnel> (_ssl, PrefixStyle.Fixed32BigEndian);

where _ssl是SslStream

这是我的完整方法

nternal void ProcessTcpData ()
{
        try {
                var masg = IPAddress.NetworkToHostOrder (_reader.ReadInt16 ());
                MessageType messageType = (MessageType)masg;
                Debug.Log ("Received message type: " + messageType);
                switch (messageType) {
                case MessageType.Version:
                        _mc.RemoteVersion = Serializer.DeserializeWithLengthPrefix<Version> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.CryptSetup:
                        var cryptSetup = Serializer.DeserializeWithLengthPrefix<CryptSetup> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        ProcessCryptSetup (cryptSetup);
                        break;
                case MessageType.CodecVersion:
                        _mc.CodecVersion = Serializer.DeserializeWithLengthPrefix<CodecVersion> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.ChannelState:
                        _mc.ChannelState = Serializer.DeserializeWithLengthPrefix<ChannelState> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.PermissionQuery:
                        _mc.PermissionQuery = Serializer.DeserializeWithLengthPrefix<PermissionQuery> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.UserState:
                        _mc.UserState = Serializer.DeserializeWithLengthPrefix<UserState> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.ServerSync:
                        _mc.ServerSync = Serializer.DeserializeWithLengthPrefix<ServerSync> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        _mc.ConnectionSetupFinished = true;
                        break;
                case MessageType.ServerConfig:
                        _mc.ServerConfig = Serializer.DeserializeWithLengthPrefix<ServerConfig> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        _validConnection = true; // handshake complete
                        break;
                case MessageType.TextMessage:
                        var textMessage = Serializer.DeserializeWithLengthPrefix<TextMessage> (_ssl, PrefixStyle.Fixed32BigEndian);
                        break;
                case MessageType.UDPTunnel:
                        if (_validConnection) {
                                var udpTunnel = Serializer.DeserializeWithLengthPrefix<UDPTunnel> (_ssl, PrefixStyle.Fixed32BigEndian);
                        }
                        break;
                case MessageType.Ping:
                        var ping = Serializer.DeserializeWithLengthPrefix<MumbleProto.Ping> (_ssl, PrefixStyle.Fixed32BigEndian);
                        Debug.Log ("Received ping: " + ping.timestamp + ", udp: " + ping.udp_packets + ", tcp:" +
                                ping.tcp_packets);
                        break;
                case MessageType.Reject:
                        var reject = Serializer.DeserializeWithLengthPrefix<Reject> (_ssl,
PrefixStyle.Fixed32BigEndian);
                        _validConnection = false;
                        _errorCallback ("Mumble server reject: " + reject.reason, true);
                        break;
                default:
                        _errorCallback ("Message type " + messageType + " not implemented", true);
                        break;
                }
                if (_validConnection) {
                        Debug.Log ("Handshake Complete:'tconnection is valid");
                }
        } catch (Exception ex) {
                Debug.LogException (ex);
        }
}

_reader是一个BinaryReader