private static async Task PerformAuth(Socket socket, Socks5Options options)
{
/*
+-----+------+----------+------+----------+
| VER | ULEN | UNAME | PLEN | PASSWD |
+----+-------+----------+------+----------+
| 1 | 1 | 1 to 255 | 1 | 1 to 255 |
+----+-------+----------+------+----------+
*/
var buffer = ConstructAuthBuffer(options.Credentials.Username, options.Credentials.Password);
await socket.SendAsync(buffer, SocketFlags.None);
/*
+----+--------+
|VER | STATUS |
+----+--------+
| 1 | 1 |
+----+--------+
*/
var response = new byte[2];
var read = await socket.ReceiveAsync(response, SocketFlags.None);
if (read != 2)
{
throw new SocksocketException($"Failed to perform authentication, the server sent {read} bytes.");
}
if (response[1] != 0)
{
socket.Close();
throw new SocksocketException("Proxy authentication failed.");
}
}
private static async Task SelectAuth(Socket socket, Socks5Options options)
{
/*
+----+----------+----------+
| VER | NMETHODS | METHODS |
+----+----------+----------+
| 1 | 1 | 1 to 255 |
+----+----------+----------+
*/
var buffer = new byte[4] {
5,
2,
Socks5Constants.AuthMethodNoAuthenticationRequired, Socks5Constants.AuthMethodUsernamePassword
};
await socket.SendAsync(buffer, SocketFlags.None);
/*
+-----+--------+
| VER | METHOD |
+-----+--------+
| 1 | 1 |
+-----+--------+
*/
var response = new byte[2];
var read = await socket.ReceiveAsync(response, SocketFlags.None);
if (read != 2)
{
throw new SocksocketException($"Failed to select an authentication method, the server sent {read} bytes.");
}
if (response[1] == Socks5Constants.AuthMethodReplyNoAcceptableMethods)
{
socket.Close();
throw new SocksocketException("The proxy destination does not accept the supported proxy client authentication methods.");
}
if (response[1] == Socks5Constants.AuthMethodUsernamePassword && options.Auth == AuthType.None)
{
socket.Close();
throw new SocksocketException("The proxy destination requires a username and password for authentication.");
}
if (response[1] == Socks5Constants.AuthMethodNoAuthenticationRequired)
{
return;
}
await PerformAuth(socket, options);
}
public static async Task <Socket> Connect(Func <Socket> socketFactory, Socks5Options options)
{
if (options == null)
{
throw new ArgumentNullException(nameof(options));
}
var socket = socketFactory();
await socket.ConnectAsync(options.ProxyHost, options.ProxyPort);
await SelectAuth(socket, options);
await Connect(socket, options);
return(socket);
}
private static async Task Connect(Socket socket, Socks5Options options)
{
/*
+-----+-----+-------+------+----------+----------+
| VER | CMD | RSV | ATYP | DST.ADDR | DST.PORT |
+--- -+-----+-------+------+----------+----------+
| 1 | 1 | X'00' | 1 | Variable | 2 |
+-----+-----+-------+------+----------+----------+
*/
var addressType = GetDestAddressType(options.DestinationHost);
var destAddr = GetDestAddressBytes(addressType, options.DestinationHost);
var destPort = GetDestPortBytes(options.DestinationPort);
var buffer = new byte[6 + options.DestinationHost.Length];
buffer[0] = 5;
buffer[1] = Socks5Constants.CmdConnect;
buffer[2] = Socks5Constants.Reserved;
buffer[3] = addressType;
destAddr.CopyTo(buffer, 4);
destPort.CopyTo(buffer, 4 + destAddr.Length);
await socket.SendAsync(buffer, SocketFlags.None);
/*
+---- +-----+-------+------+----------+----------+
| VER | REP | RSV | ATYP | BND.ADDR | BND.PORT |
+-----+-----+-------+------+----------+----------+
| 1 | 1 | X'00' | 1 | Variable | 2 |
+-----+-----+-------+------+----------+----------+
*/
var response = new byte[255];
await socket.ReceiveAsync(response, SocketFlags.None);
if (response[1] != Socks5Constants.CmdReplySucceeded)
{
HandleProxyCommandError(response, options.DestinationHost, options.DestinationPort);
}
}
