public static SocketConnectionResult TryCreateTunnel(Socket socks5Socket, string destAddress, int destPort, ProxyInfo proxy, bool resolveHostnamesLocally)
{
try
{
// SEND HELLO
socks5Socket.Send(BuildHelloMessage(proxy.Authenticate));
// RECEIVE HELLO RESPONSE - HANDLE AUTHENTICATION
byte[] buffer = new byte[255];
if (socks5Socket.Receive(buffer) != 2)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[0] != SocksVersion)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[1] == (byte)Authentication.UsernamePassword)
{
if (!proxy.Authenticate)
{
// Proxy server is requesting UserPass auth even tho we did not allow it
return(SocketConnectionResult.InvalidProxyResponse);
}
else
{
// We have to try and authenticate using the Username and Password
// https://tools.ietf.org/html/rfc1929
socks5Socket.Send(proxy.AuthenticationMessage);
if (socks5Socket.Receive(buffer) != 2)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[0] != SubnegotiationVersion)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[1] != 0)
{
return(SocketConnectionResult.AuthenticationError);
}
}
}
else if (buffer[1] != (byte)Authentication.NoAuthentication)
{
return(SocketConnectionResult.AuthenticationError);
}
if (resolveHostnamesLocally && Helpers.GetAddressType(destAddress) == AddressType.DomainName)
{
destAddress = destAddress.Resolve().ToString();
}
// SEND REQUEST
socks5Socket.Send(BuildRequestMessage(Command.Connect, Helpers.GetAddressType(destAddress), destAddress, destPort));
// RECEIVE RESPONSE
int received = socks5Socket.Receive(buffer);
if (received < 8)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[0] != SocksVersion)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[1] > 8)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[1] != 0)
{
return((SocketConnectionResult)buffer[1]);
}
if (buffer[2] != 0)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
if (buffer[3] != 1 && buffer[3] != 3 && buffer[3] != 4)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
AddressType boundAddress = (AddressType)buffer[3];
if (boundAddress == AddressType.IPv4)
{
if (received != 10)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
}
else if (boundAddress == AddressType.IPv6)
{
if (received != 22)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
}
else
{
int domainLength = buffer[4];
if (received != 7 + domainLength)
{
return(SocketConnectionResult.InvalidProxyResponse);
}
}
return(SocketConnectionResult.OK);
}
catch (SocketException ex)
{
return(ex.ToConnectionResult());
}
catch
{
return(SocketConnectionResult.UnknownError);
}
}