private static byte Serialize(MqttSubscribePacket packet, MqttPacketWriter packetWriter)
{
if (!packet.TopicFilters.Any())
{
throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.8.3-3].");
}
if (!packet.PacketIdentifier.HasValue)
{
throw new MqttProtocolViolationException("Subscribe packet has no packet identifier.");
}
packetWriter.Write(packet.PacketIdentifier.Value);
if (packet.TopicFilters?.Count > 0)
{
foreach (var topicFilter in packet.TopicFilters)
{
packetWriter.WriteWithLengthPrefix(topicFilter.Topic);
packetWriter.Write((byte)topicFilter.QualityOfServiceLevel);
}
}
return(MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Subscribe, 0x02));
}
private static byte Serialize(MqttPublishPacket packet, MqttPacketWriter packetWriter)
{
ValidatePublishPacket(packet);
packetWriter.WriteWithLengthPrefix(packet.Topic);
if (packet.QualityOfServiceLevel > MqttQualityOfServiceLevel.AtMostOnce)
{
if (!packet.PacketIdentifier.HasValue)
{
throw new MqttProtocolViolationException("Publish packet has no packet identifier.");
}
packetWriter.Write(packet.PacketIdentifier.Value);
}
else
{
if (packet.PacketIdentifier > 0)
{
throw new MqttProtocolViolationException("Packet identifier must be empty if QoS == 0 [MQTT-2.3.1-5].");
}
}
if (packet.Payload?.Length > 0)
{
packetWriter.Write(packet.Payload, 0, packet.Payload.Length);
}
byte fixedHeader = 0;
if (packet.Retain)
{
fixedHeader |= 0x01;
}
fixedHeader |= (byte)((byte)packet.QualityOfServiceLevel << 1);
if (packet.Dup)
{
fixedHeader |= 0x08;
}
return(MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Publish, fixedHeader));
}
private static byte Serialize(MqttUnsubscribePacket packet, MqttPacketWriter packetWriter)
{
if (!packet.TopicFilters.Any())
{
throw new MqttProtocolViolationException("At least one topic filter must be set [MQTT-3.10.3-2].");
}
if (!packet.PacketIdentifier.HasValue)
{
throw new MqttProtocolViolationException("Unsubscribe packet has no packet identifier.");
}
packetWriter.Write(packet.PacketIdentifier.Value);
if (packet.TopicFilters?.Any() == true)
{
foreach (var topicFilter in packet.TopicFilters)
{
packetWriter.WriteWithLengthPrefix(topicFilter);
}
}
return(MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Unsubscibe, 0x02));
}
private byte Serialize(MqttConnectPacket packet, MqttPacketWriter packetWriter)
{
ValidateConnectPacket(packet);
// Write variable header
if (ProtocolVersion == MqttProtocolVersion.V311)
{
packetWriter.WriteWithLengthPrefix("MQTT");
packetWriter.Write(4); // 3.1.2.2 Protocol Level 4
}
else
{
packetWriter.WriteWithLengthPrefix("MQIsdp");
packetWriter.Write(3); // Protocol Level 3
}
byte connectFlags = 0x0;
if (packet.CleanSession)
{
connectFlags |= 0x2;
}
if (packet.WillMessage != null)
{
connectFlags |= 0x4;
connectFlags |= (byte)((byte)packet.WillMessage.QualityOfServiceLevel << 3);
if (packet.WillMessage.Retain)
{
connectFlags |= 0x20;
}
}
if (packet.Password != null && packet.Username == null)
{
throw new MqttProtocolViolationException("If the User Name Flag is set to 0, the Password Flag MUST be set to 0 [MQTT-3.1.2-22].");
}
if (packet.Password != null)
{
connectFlags |= 0x40;
}
if (packet.Username != null)
{
connectFlags |= 0x80;
}
packetWriter.Write(connectFlags);
packetWriter.Write(packet.KeepAlivePeriod);
packetWriter.WriteWithLengthPrefix(packet.ClientId);
if (packet.WillMessage != null)
{
packetWriter.WriteWithLengthPrefix(packet.WillMessage.Topic);
packetWriter.WriteWithLengthPrefix(packet.WillMessage.Payload);
}
if (packet.Username != null)
{
packetWriter.WriteWithLengthPrefix(packet.Username);
}
if (packet.Password != null)
{
packetWriter.WriteWithLengthPrefix(packet.Password);
}
return(MqttPacketWriter.BuildFixedHeader(MqttControlPacketType.Connect));
}