private bool IsConnected(ClientMetadata client)
{
if (client.TcpClient.Connected)
{
if ((client.TcpClient.Client.Poll(0, SelectMode.SelectWrite)) && (!client.TcpClient.Client.Poll(0, SelectMode.SelectError)))
{
byte[] buffer = new byte[1];
if (client.TcpClient.Client.Receive(buffer, SocketFlags.Peek) == 0)
{
return(false);
}
else
{
return(true);
}
}
else
{
return(false);
}
}
else
{
return(false);
}
}
private void FinalizeConnection(ClientMetadata client)
{
#region Add-to-Client-List
if (!AddClient(client))
{
Log("*** FinalizeConnection unable to add client " + client.IpPort);
client.Dispose();
return;
}
// Do not decrement in this block, decrement is done by the connection reader
int activeCount = Interlocked.Increment(ref _ActiveClients);
#endregion
#region Start-Data-Receiver
Log("*** FinalizeConnection starting data receiver for " + client.IpPort + " (now " + activeCount + " clients)");
if (_ClientConnected != null)
{
Task.Run(() => _ClientConnected(client.IpPort));
}
Task.Run(async() => await DataReceiver(client));
#endregion
}
private bool AddClient(ClientMetadata client)
{
if (!_Clients.TryRemove(client.IpPort, out ClientMetadata removedClient))
{
// do nothing, it probably did not exist anyway
}
_Clients.TryAdd(client.IpPort, client);
Log("*** AddClient added client " + client.IpPort);
return(true);
}
private async Task <bool> MessageWriteAsync(ClientMetadata client, byte[] data)
{
try
{
#region Format-Message
string header = "";
byte[] headerBytes;
byte[] message;
if (data == null || data.Length < 1)
{
header += "0:";
}
else
{
header += data.Length + ":";
}
headerBytes = Encoding.UTF8.GetBytes(header);
int messageLen = headerBytes.Length;
if (data != null && data.Length > 0)
{
messageLen += data.Length;
}
message = new byte[messageLen];
Buffer.BlockCopy(headerBytes, 0, message, 0, headerBytes.Length);
if (data != null && data.Length > 0)
{
Buffer.BlockCopy(data, 0, message, headerBytes.Length, data.Length);
}
#endregion
#region Send-Message-Async
await client.NetworkStream.WriteAsync(message, 0, message.Length);
await client.NetworkStream.FlushAsync();
return(true);
#endregion
}
catch (Exception)
{
Log("*** MessageWriteAsync " + client.IpPort + " disconnected due to exception");
return(false);
}
}
private bool RemoveClient(ClientMetadata client)
{
if (!_Clients.TryRemove(client.IpPort, out ClientMetadata removedClient))
{
Log("*** RemoveClient unable to remove client " + client.IpPort);
return(false);
}
else
{
Log("*** RemoveClient removed client " + client.IpPort);
return(true);
}
}
private async Task DataReceiver(ClientMetadata client)
{
try
{
#region Wait-for-Data
while (true)
{
try
{
if (!IsConnected(client))
{
break;
}
byte[] data = await MessageReadAsync(client);
if (data == null)
{
// no message available
await Task.Delay(30);
continue;
}
if (_MessageReceived != null)
{
Task <bool> unawaited = Task.Run(() => _MessageReceived(client.IpPort, data));
}
}
catch (Exception)
{
break;
}
}
#endregion
}
finally
{
int activeCount = Interlocked.Decrement(ref _ActiveClients);
RemoveClient(client);
if (_ClientDisconnected != null)
{
Task <bool> unawaited = Task.Run(() => _ClientDisconnected(client.IpPort));
}
Log("*** DataReceiver client " + client.IpPort + " disconnected (now " + activeCount + " clients active)");
client.Dispose();
}
}
private async Task <byte[]> MessageReadAsync(ClientMetadata client)
{
/*
*
* Do not catch exceptions, let them get caught by the data reader
* to destroy the connection
*
*/
#region Variables
int bytesRead = 0;
int sleepInterval = 25;
int maxTimeout = 500;
int currentTimeout = 0;
bool timeout = false;
byte[] headerBytes;
string header = "";
long contentLength;
byte[] contentBytes;
if (!client.NetworkStream.CanRead)
{
return(null);
}
if (!client.NetworkStream.DataAvailable)
{
return(null);
}
#endregion
#region Read-Header
using (MemoryStream headerMs = new MemoryStream())
{
#region Read-Header-Bytes
byte[] headerBuffer = new byte[1];
timeout = false;
currentTimeout = 0;
int read = 0;
while ((read = await client.NetworkStream.ReadAsync(headerBuffer, 0, headerBuffer.Length)) > 0)
{
if (read > 0)
{
await headerMs.WriteAsync(headerBuffer, 0, read);
bytesRead += read;
// reset timeout since there was a successful read
currentTimeout = 0;
}
else
{
#region Check-for-Timeout
if (currentTimeout >= maxTimeout)
{
timeout = true;
break;
}
else
{
currentTimeout += sleepInterval;
await Task.Delay(sleepInterval);
}
if (timeout)
{
break;
}
#endregion
}
if (bytesRead > 1)
{
// check if end of headers reached
if (headerBuffer[0] == 58)
{
break;
}
}
else
{
#region Check-for-Timeout
if (currentTimeout >= maxTimeout)
{
timeout = true;
break;
}
else
{
currentTimeout += sleepInterval;
await Task.Delay(sleepInterval);
}
if (timeout)
{
break;
}
#endregion
}
}
if (timeout)
{
Log("*** MessageReadAsync timeout " + currentTimeout + "ms/" + maxTimeout + "ms exceeded while reading header after reading " + bytesRead + " bytes");
return(null);
}
headerBytes = headerMs.ToArray();
if (headerBytes == null || headerBytes.Length < 1)
{
return(null);
}
#endregion
#region Process-Header
header = Encoding.UTF8.GetString(headerBytes);
header = header.Replace(":", "");
if (!Int64.TryParse(header, out contentLength))
{
Log("*** MessageReadAsync malformed message from " + client.IpPort + " (message header not an integer)");
return(null);
}
#endregion
}
#endregion
#region Read-Data
using (MemoryStream dataMs = new MemoryStream())
{
long bytesRemaining = contentLength;
timeout = false;
currentTimeout = 0;
int read = 0;
byte[] buffer;
long bufferSize = 2048;
if (bufferSize > bytesRemaining)
{
bufferSize = bytesRemaining;
}
buffer = new byte[bufferSize];
while ((read = await client.NetworkStream.ReadAsync(buffer, 0, buffer.Length)) > 0)
{
if (read > 0)
{
dataMs.Write(buffer, 0, read);
bytesRead = bytesRead + read;
bytesRemaining = bytesRemaining - read;
// reset timeout
currentTimeout = 0;
// reduce buffer size if number of bytes remaining is
// less than the pre-defined buffer size of 2KB
if (bytesRemaining < bufferSize)
{
bufferSize = bytesRemaining;
}
buffer = new byte[bufferSize];
// check if read fully
if (bytesRemaining == 0)
{
break;
}
if (bytesRead == contentLength)
{
break;
}
}
else
{
#region Check-for-Timeout
if (currentTimeout >= maxTimeout)
{
timeout = true;
break;
}
else
{
currentTimeout += sleepInterval;
await Task.Delay(sleepInterval);
}
if (timeout)
{
break;
}
#endregion
}
}
if (timeout)
{
Log("*** MessageReadAsync timeout " + currentTimeout + "ms/" + maxTimeout + "ms exceeded while reading content after reading " + bytesRead + " bytes");
return(null);
}
contentBytes = dataMs.ToArray();
}
#endregion
#region Check-Content-Bytes
if (contentBytes == null || contentBytes.Length < 1)
{
Log("*** MessageReadAsync " + client.IpPort + " no content read");
return(null);
}
if (contentBytes.Length != contentLength)
{
Log("*** MessageReadAsync " + client.IpPort + " content length " + contentBytes.Length + " bytes does not match header value " + contentLength + ", discarding");
return(null);
}
#endregion
return(contentBytes);
}
private async Task AcceptConnections()
{
_Listener.Start();
while (!_Token.IsCancellationRequested)
{
string clientIpPort = String.Empty;
try
{
#region Accept-Connection
TcpClient tcpClient = await _Listener.AcceptTcpClientAsync();
tcpClient.LingerState.Enabled = false;
#endregion
#region Get-Tuple-and-Check-IP
string clientIp = ((IPEndPoint)tcpClient.Client.RemoteEndPoint).Address.ToString();
if (_PermittedIps != null && _PermittedIps.Count > 0)
{
if (!_PermittedIps.Contains(clientIp))
{
Log("*** AcceptConnections rejecting connection from " + clientIp + " (not permitted)");
tcpClient.Close();
continue;
}
}
#endregion
ClientMetadata client = new ClientMetadata(tcpClient);
clientIpPort = client.IpPort;
Log("*** AcceptConnections accepted connection from " + client.IpPort);
Task unawaited = Task.Run(() =>
{
FinalizeConnection(client);
}, _Token);
}
catch (ObjectDisposedException ex)
{
// Listener stopped ? if so, clientIpPort will be empty
Log("*** AcceptConnections ObjectDisposedException from " + clientIpPort + Environment.NewLine + ex.ToString());
}
catch (SocketException ex)
{
switch (ex.Message)
{
case "An existing connection was forcibly closed by the remote host":
Log("*** AcceptConnections SocketException " + clientIpPort + " closed the connection.");
break;
default:
Log("*** AcceptConnections SocketException from " + clientIpPort + Environment.NewLine + ex.ToString());
break;
}
}
catch (Exception ex)
{
Log("*** AcceptConnections Exception from " + clientIpPort + Environment.NewLine + ex.ToString());
}
}
}