/// <summary>
/// Sends a message to the client over the open network stream.
/// </summary>
/// <param name="Message">Message to send.</param>
/// <returns>true if the message was sent successfully to the target recipient.</returns>
protected async Task <bool> SendMessageInternalAsync(Message Message)
{
log.Trace("()");
bool res = false;
string msgStr = Message.ToString();
log.Trace("Sending message:\n{0}", msgStr.SubstrMax(512));
byte[] messageBytes = ProtocolHelper.GetMessageBytes(Message);
await streamWriteLock.WaitAsync();
try
{
if (Stream != null)
{
await Stream.WriteAsync(messageBytes, 0, messageBytes.Length);
res = true;
}
else
{
log.Info("Connection to the client has been terminated.");
}
}
catch (IOException)
{
log.Info("Connection to the client has been terminated.");
}
finally
{
streamWriteLock.Release();
}
log.Trace("(-):{0}", res);
return(res);
}
/// <summary>
/// Asynchronous read and processing function for each client that connects to the TCP server.
/// </summary>
/// <param name="Client">Client that is connected to TCP server.</param>
/// <remarks>The client is being handled in the processing loop until the connection to it
/// is terminated by either side. This function implements reading the message from the network stream,
/// which includes reading the message length prefix followed by the entire message.</remarks>
private async void ClientHandlerAsync(Client Client)
{
this.log.Info("(Client.RemoteEndPoint:{0})", Client.RemoteEndPoint);
string prefix = string.Format("{0}[{1}] ", this.logPrefix, Client.RemoteEndPoint);
PrefixLogger log = new PrefixLogger(this.logName, prefix);
clientList.AddNetworkPeer(Client);
log.Debug("Client ID set to 0x{0:X16}.", Client.Id);
await Client.ReceiveMessageLoop();
// Free resources used by the client.
clientList.RemoveNetworkPeer(Client);
await Client.HandleDisconnect();
Client.Dispose();
log.Info("(-)");
}
/// <summary>
/// <para>Starts the TCP server listener and starts client thread handlers.</para>
/// <para>If the application is restarted, it may be the case that the TCP port
/// is unusable for a short period of time. This method repeatedly tries to reuse that port until it succeeds
/// or until 10 unsuccessful attempts are reached.</para>
/// </summary>
/// <returns>true if the function succeeds, false otherwise</returns>
public bool Start()
{
log.Info("(Roles:[{0}])", this.Roles);
int tryCounter = 0;
bool res = false;
while (tryCounter < 10)
{
try
{
this.Listener.Server.SetSocketOption(SocketOptionLevel.Socket, SocketOptionName.ReuseAddress, true);
this.Listener.Start();
res = true;
break;
}
catch (SocketException se)
{
log.Info("Socket error code {0} occurred while trying to reuse socket: {1}.", se.SocketErrorCode, se.ToString());
}
int waitTime = tryCounter * 3;
log.Info("Will wait {0} seconds and then try again.", waitTime);
Thread.Sleep(waitTime * 1000);
tryCounter--;
}
if (res)
{
clientQueueHandlerThread = new Thread(new ThreadStart(ClientQueueHandlerThread));
clientQueueHandlerThread.Start();
acceptThread = new Thread(new ThreadStart(AcceptThread));
acceptThread.Start();
IsRunning = true;
}
log.Info("(-):{0}", res);
return(res);
}
/// <summary>
/// Reads messages from the client stream and processes them in a loop until the client disconnects
/// or until an action (such as a protocol violation) that leads to disconnecting of the client occurs.
/// </summary>
public async Task ReceiveMessageLoop()
{
log.Trace("()");
try
{
if (UseTls)
{
SslStream sslStream = (SslStream)Stream;
await sslStream.AuthenticateAsServerAsync(Base.Configuration.TcpServerTlsCertificate, false, SslProtocols.Tls12, false);
}
Stream clientStream = Stream;
byte[] messageHeaderBuffer = new byte[ProtocolHelper.HeaderSize];
byte[] messageBuffer = null;
ClientStatus clientStatus = ClientStatus.ReadingHeader;
uint messageSize = 0;
int messageHeaderBytesRead = 0;
int messageBytesRead = 0;
while (!server.ShutdownSignaling.IsShutdown)
{
Task <int> readTask = null;
int remain = 0;
log.Trace("Client status is '{0}'.", clientStatus);
switch (clientStatus)
{
case ClientStatus.ReadingHeader:
{
remain = ProtocolHelper.HeaderSize - messageHeaderBytesRead;
readTask = clientStream.ReadAsync(messageHeaderBuffer, messageHeaderBytesRead, remain, server.ShutdownSignaling.ShutdownCancellationTokenSource.Token);
break;
}
case ClientStatus.ReadingBody:
{
remain = (int)messageSize - messageBytesRead;
readTask = clientStream.ReadAsync(messageBuffer, ProtocolHelper.HeaderSize + messageBytesRead, remain, server.ShutdownSignaling.ShutdownCancellationTokenSource.Token);
break;
}
default:
log.Error("Invalid client status '{0}'.", clientStatus);
break;
}
if (readTask == null)
{
break;
}
log.Trace("{0} bytes remains to be read.", remain);
int readAmount = await readTask;
if (readAmount == 0)
{
log.Info("Connection has been closed.");
break;
}
log.Trace("Read completed: {0} bytes.", readAmount);
bool protoViolationDisconnect = false;
bool disconnect = false;
switch (clientStatus)
{
case ClientStatus.ReadingHeader:
{
messageHeaderBytesRead += readAmount;
if (readAmount == remain)
{
if (messageHeaderBuffer[0] == 0x0D)
{
uint hdr = ProtocolHelper.GetValueLittleEndian(messageHeaderBuffer, 1);
if (hdr + ProtocolHelper.HeaderSize <= ProtocolHelper.MaxSize)
{
messageSize = hdr;
clientStatus = ClientStatus.ReadingBody;
messageBuffer = new byte[ProtocolHelper.HeaderSize + messageSize];
Array.Copy(messageHeaderBuffer, messageBuffer, messageHeaderBuffer.Length);
log.Trace("Reading of message header completed. Message size is {0} bytes.", messageSize);
}
else
{
log.Warn("Client claimed message of size {0} which exceeds the maximum.", hdr + ProtocolHelper.HeaderSize);
protoViolationDisconnect = true;
}
}
else
{
log.Warn("Message has invalid format - it's first byte is 0x{0:X2}, should be 0x0D.", messageHeaderBuffer[0]);
protoViolationDisconnect = true;
}
}
break;
}
case ClientStatus.ReadingBody:
{
messageBytesRead += readAmount;
if (readAmount == remain)
{
clientStatus = ClientStatus.ReadingHeader;
messageBytesRead = 0;
messageHeaderBytesRead = 0;
log.Trace("Reading of message size {0} completed.", messageSize);
Message incomingMessage = CreateMessageFromRawData(messageBuffer);
if (incomingMessage != null)
{
disconnect = !await messageProcessor.ProcessMessageAsync(this, incomingMessage);
}
else
{
protoViolationDisconnect = true;
}
}
break;
}
}
if (protoViolationDisconnect)
{
await messageProcessor.SendProtocolViolation(this);
break;
}
if (disconnect)
{
break;
}
}
}
catch (Exception e)
{
if ((e is ObjectDisposedException) || (e is IOException))
{
log.Info("Connection to client has been terminated.");
}
else
{
log.Error("Exception occurred: {0}", e.ToString());
}
}
log.Trace("(-)");
}
