private static void EncodeFbnsConnectPacket(FbnsConnectPacket packet, DataWriter writer)
{
var payload = packet.Payload;
uint payloadSize = payload?.Length ?? 0;
byte[] protocolNameBytes = EncodeStringInUtf8(packet.ProtocolName);
// variableHeaderwriterferSize = 2 bytes length + ProtocolName bytes + 4 bytes
// 4 bytes are reserved for: 1 byte ProtocolLevel, 1 byte ConnectFlags, 2 byte KeepAlive
uint variableHeaderwriterferSize = (uint)(STRING_SIZE_LENGTH + protocolNameBytes.Length + 4);
uint variablePartSize = variableHeaderwriterferSize + payloadSize;
// MQTT message format from: http://public.dhe.ibm.com/software/dw/webservices/ws-mqtt/MQTT_V3.1_Protocol_Specific.pdf
writer.WriteByte((byte)((int)packet.PacketType << 4)); // Write packet type
WriteVariableLengthInt(writer, variablePartSize); // Write remaining length
// Variable part
writer.WriteUInt16((ushort)protocolNameBytes.Length);
writer.WriteBytes(protocolNameBytes);
writer.WriteByte(packet.ProtocolLevel);
writer.WriteByte(packet.ConnectFlags);
writer.WriteUInt16(packet.KeepAliveInSeconds);
if (payload != null)
{
writer.WriteBuffer(payload);
}
}
private static Packet DecodePacketInternal(DataReader reader, int packetSignature, ref uint remainingLength)
{
if (Signatures.IsPublish(packetSignature))
{
var qualityOfService =
(QualityOfService)((packetSignature >> 1) &
0x3); // take bits #1 and #2 ONLY and convert them into QoS value
if (qualityOfService == QualityOfService.Reserved)
{
throw new DecoderException(
$"Unexpected QoS value of {(int)qualityOfService} for {PacketType.PUBLISH} packet.");
}
bool duplicate = (packetSignature & 0x8) == 0x8; // test bit#3
bool retain = (packetSignature & 0x1) != 0; // test bit#0
var packet = new PublishPacket(qualityOfService, duplicate, retain);
DecodePublishPacket(reader, packet, ref remainingLength);
return(packet);
}
switch (packetSignature & 240) // We don't care about flags for these packets
{
case Signatures.Subscribe& 240:
var subscribePacket = new SubscribePacket();
DecodePacketIdVariableHeader(reader, subscribePacket, ref remainingLength);
DecodeSubscribePayload(reader, subscribePacket, ref remainingLength);
return(subscribePacket);
case Signatures.Connect:
var connectPacket = new FbnsConnectPacket();
DecodeConnectPacket(reader, connectPacket, ref remainingLength);
return(connectPacket);
case Signatures.ConnAck:
var connAckPacket = new FbnsConnAckPacket();
DecodeConnAckPacket(reader, connAckPacket, ref remainingLength);
return(connAckPacket);
case Signatures.SubAck:
var subAckPacket = new SubAckPacket();
DecodePacketIdVariableHeader(reader, subAckPacket, ref remainingLength);
DecodeSubAckPayload(reader, subAckPacket, ref remainingLength);
return(subAckPacket);
case Signatures.Unsubscribe& 240:
var unsubscribePacket = new UnsubscribePacket();
DecodePacketIdVariableHeader(reader, unsubscribePacket, ref remainingLength);
DecodeUnsubscribePayload(reader, unsubscribePacket, ref remainingLength);
return(unsubscribePacket);
case Signatures.PingResp:
return(PingRespPacket.Instance);
case Signatures.PubAck:
var pubAckPacket = new PubAckPacket();
DecodePacketIdVariableHeader(reader, pubAckPacket, ref remainingLength);
return(pubAckPacket);
default: return(null);
//default:
// throw new DecoderException($"Packet type {packetSignature} not supported");
}
}
static void DecodeConnectPacket(DataReader reader, FbnsConnectPacket packet, ref uint remainingLength)
{
string protocolName = DecodeString(reader, ref remainingLength);
// if (!PROTOCOL_NAME.Equals(protocolName, StringComparison.Ordinal))
// {
// throw new DecoderException($"Unexpected protocol name. Expected: {PROTOCOL_NAME}. Actual: {protocolName}");
// }
packet.ProtocolName = protocolName;
DecreaseRemainingLength(ref remainingLength, 1);
packet.ProtocolLevel = reader.ReadByte();
// if (packet.ProtocolLevel != Util.ProtocolLevel)
// {
// var connAckPacket = new ConnAckPacket();
// connAckPacket.ReturnCode = ConnectReturnCode.RefusedUnacceptableProtocolVersion;
// context.WriteAndFlushAsync(connAckPacket);
// throw new DecoderException($"Unexpected protocol level. Expected: {Util.ProtocolLevel}. Actual: {packet.ProtocolLevel}");
// }
DecreaseRemainingLength(ref remainingLength, 1);
int connectFlags = reader.ReadByte();
packet.CleanSession = (connectFlags & 0x02) == 0x02;
bool hasWill = (connectFlags & 0x04) == 0x04;
if (hasWill)
{
packet.HasWill = true;
packet.WillRetain = (connectFlags & 0x20) == 0x20;
packet.WillQualityOfService = (QualityOfService)((connectFlags & 0x18) >> 3);
if (packet.WillQualityOfService == QualityOfService.Reserved)
{
throw new DecoderException($"[MQTT-3.1.2-14] Unexpected Will QoS value of {(int)packet.WillQualityOfService}.");
}
packet.WillTopicName = string.Empty;
}
else if ((connectFlags & 0x38) != 0) // bits 3,4,5 [MQTT-3.1.2-11]
{
throw new DecoderException("[MQTT-3.1.2-11]");
}
packet.HasUsername = (connectFlags & 0x80) == 0x80;
packet.HasPassword = (connectFlags & 0x40) == 0x40;
if (packet.HasPassword && !packet.HasUsername)
{
throw new DecoderException("[MQTT-3.1.2-22]");
}
if ((connectFlags & 0x1) != 0) // [MQTT-3.1.2-3]
{
throw new DecoderException("[MQTT-3.1.2-3]");
}
packet.KeepAliveInSeconds = DecodeUnsignedShort(reader, ref remainingLength);
string clientId = DecodeString(reader, ref remainingLength);
if (string.IsNullOrEmpty(clientId))
{
throw new DecoderException("Client identifier is required.");
}
packet.ClientId = clientId;
if (hasWill)
{
packet.WillTopicName = DecodeString(reader, ref remainingLength);
var willMessageLength = DecodeUnsignedShort(reader, ref remainingLength);
DecreaseRemainingLength(ref remainingLength, willMessageLength);
packet.WillMessage = reader.ReadBuffer(willMessageLength);
}
if (packet.HasUsername)
{
packet.Username = DecodeString(reader, ref remainingLength);
}
if (packet.HasPassword)
{
packet.Password = DecodeString(reader, ref remainingLength);
}
}
