src/HTTP/Request2/SOCKS5.php
protected function performAuthentication($username, $password)
    {
        $request  = pack('C2', 1, strlen($username)) . $username
                    . pack('C', strlen($password)) . $password;

        $this->write($request);
        $response = unpack('Cvn/Cstatus', $this->read(3));
        if (1 != $response['vn'] || 0 != $response['status']) {
            throw new HTTP_Request2_ConnectionException(
                'Connection rejected by proxy due to invalid username and/or password'
            );
        }
    }
protected function performAuthentication($username, $password)
    {
        $request  = pack('C2', 1, strlen($username)) . $username
                    . pack('C', strlen($password)) . $password;

        $this->write($request);
        $response = unpack('Cvn/Cstatus', $this->read(3));
        if (1 != $response['vn'] || 0 != $response['status']) {
            throw new HTTP_Request2_ConnectionException(
                'Connection rejected by proxy due to invalid username and/or password'
            );
        }
    }
Performs username/password authentication for SOCKS5

@param string $username Proxy user name
@param string $password Proxy password

@throws HTTP_Request2_ConnectionException
@throws HTTP_Request2_MessageException
@link http://tools.ietf.org/html/rfc1929