private void socket_Receive(IAsyncResult ar)
{
try
{
int received = Handle.EndReceive(ar);
if (received <= 0)
{
Disconnect();
return;
}
if (received > 5000 || _handshakeStream.Length + received > 5000)
{
//attack prevention of overflowing the HandshakeStream
//It's really impossible for Socks or HTTPS proxies to use even 5000 for Initial Packets
Disconnect();
return;
}
LengthReceived += received;
_handshakeStream.Write(_buffer, 0, received);
}
catch
{
Disconnect();
return;
}
byte[] payload = _handshakeStream.ToArray();
switch (PacketsReceived)
{
case 0:
{
//initial Socks packet
if (payload.Length >= 3)
{
string headerStr = Encoding.ASCII.GetString(payload);
//check the proxy client
if (payload[0] == SOCKS5_VERSION_NUMBER)
{
Type = ProxyType.Socks5;
}
else if (headerStr.StartsWith("CONNECT") && headerStr.Contains(":"))
{
Type = ProxyType.HTTPS;
//Grab here the IP / PORT
using (StreamReader sr = new StreamReader(new MemoryStream(payload)))
{
string line = sr.ReadLine();
if (line == null)
{
break;
}
//could have done it better with RegEx... oh well
string[] split = line.Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries);
if (split.Length > 0)
{
try
{
string ipPort = split[1];
this.TargetServer = ipPort.Split(':')[0];
this.TargetPort = ushort.Parse(ipPort.Split(':')[1]);
this._isConnectCommand = true;
this._isDomainNameType = true;
//Send Command to client and wait for response from CommandHandler
new ReverseProxyConnect(ConnectionId, this.TargetServer, this.TargetPort).Execute(Client);
Server.CallonConnectionEstablished(this);
return; //Quit receiving and wait for client's response
}
catch
{
Disconnect();
}
}
}
}
else
{
break;
}
if (CheckProxyVersion(payload))
{
SendSuccessToClient();
PacketsReceived++;
_handshakeStream.SetLength(0);
Server.CallonConnectionEstablished(this);
}
}
break;
}
case 1:
{
//Socks command
int MinPacketLen = 6;
if (payload.Length >= MinPacketLen)
{
if (!CheckProxyVersion(payload))
{
return;
}
this._isConnectCommand = payload[1] == 1;
this._isBindCommand = payload[1] == 2;
this._isUdpCommand = payload[1] == 3;
this._isIpType = payload[3] == 1;
this._isDomainNameType = payload[3] == 3;
this._isIPv6NameType = payload[3] == 4;
Array.Reverse(payload, payload.Length - 2, 2);
this.TargetPort = BitConverter.ToUInt16(payload, payload.Length - 2);
if (_isConnectCommand)
{
if (_isIpType)
{
this.TargetServer = payload[4] + "." + payload[5] + "." + payload[6] + "." + payload[7];
}
else if (_isDomainNameType)
{
int domainLen = payload[4];
if (MinPacketLen + domainLen < payload.Length)
{
this.TargetServer = Encoding.ASCII.GetString(payload, 5, domainLen);
}
}
if (this.TargetServer.Length > 0)
{
//Send Command to client and wait for response from CommandHandler
new ReverseProxyConnect(ConnectionId, this.TargetServer, this.TargetPort).Execute(Client);
}
}
else
{
SendFailToClient();
return;
}
Server.CallonUpdateConnection(this);
//Quit receiving data and wait for Client's response
return;
}
break;
}
}
try
{
Handle.BeginReceive(_buffer, 0, _buffer.Length, SocketFlags.None, socket_Receive, null);
}
catch
{
Disconnect();
}
}
