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/*
Copyright (c) 2015, Arvid Norberg
All rights reserved.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef SOCKS_SERVER_HPP_INCLUDED
#define SOCKS_SERVER_HPP_INCLUDED
#include "simulator/simulator.hpp"
#ifdef __GNUC__
#pragma GCC diagnostic push
#if __GNUC__ >= 9
#pragma GCC diagnostic ignored "-Wparentheses"
#endif
#endif
#include <boost/bimap.hpp>
#ifdef __GNUC__
#pragma GCC diagnostic pop
#endif
#ifdef _MSC_VER
#pragma warning(push)
// warning C4251: X: class Y needs to have dll-interface to be used by clients of struct
#pragma warning( disable : 4251)
#endif
namespace sim
{
enum socks_flag
{
// when this flag is set, the proxy will close the client connection
// immediately after sending the response to a UDP ASSOCIATE command
disconnect_udp_associate = 1,
// when this flag is set, the reponse to UDP ASSOCIATE will contain an empty
// hostname, rather than the relay IP address
udp_associate_respond_empty_hostname = 2
};
struct SIMULATOR_DECL socks_connection : std::enable_shared_from_this<socks_connection>
{
socks_connection(asio::io_context& ios, int version, std::array<int, 3>& cmd_counts
, std::uint32_t flags, int& bind_port);
asio::ip::tcp::socket& socket() { return m_client_connection; }
void start();
private:
void on_handshake1(boost::system::error_code const& ec, size_t bytes_transferred);
void on_handshake2(boost::system::error_code const& ec, size_t bytes_transferred);
void on_handshake3(boost::system::error_code const& ec, size_t bytes_transferred);
void on_request1(boost::system::error_code const& ec, size_t bytes_transferred);
void on_request2(boost::system::error_code const& ec, size_t bytes_transferred);
void on_write(boost::system::error_code const& ec, size_t bytes_transferred
, bool close);
void close_connection();
int format_response(asio::ip::address const& addr, int port, int response);
int format_hostname_response(char const* hostname, int port, int response);
void on_connected(boost::system::error_code const& ec);
void on_request_domain_name(boost::system::error_code const& ec, size_t bytes_transferred);
void on_request_domain_lookup(boost::system::error_code const& ec
, const asio::ip::tcp::resolver::results_type ips);
void open_forward_connection(asio::ip::tcp::endpoint const& target);
void bind_connection(asio::ip::tcp::endpoint const& target);
void start_accept(boost::system::error_code const& ec);
void udp_associate(asio::ip::tcp::endpoint const& target);
void on_read_udp(boost::system::error_code const& ec, std::size_t bytes_transferred);
void wait_for_eof(boost::system::error_code const& ec, std::size_t bytes_transferred);
void on_server_receive(boost::system::error_code const& ec
, std::size_t bytes_transferred);
void on_server_forward(boost::system::error_code const& ec
, size_t bytes_transferred);
void on_client_receive(boost::system::error_code const& ec
, std::size_t bytes_transferred);
void on_client_forward(boost::system::error_code const& ec
, size_t bytes_transferred);
char const* command() const;
int& m_bind_port;
asio::io_context& m_ios;
asio::ip::udp::resolver m_udp_resolver;
asio::ip::tcp::resolver m_resolver;
boost::bimap<asio::ip::address, std::string> m_name_mapping;
// this is the SOCKS client connection, i.e. the client connecting to us and
// being forwarded
asio::ip::tcp::socket m_client_connection;
// this is the connection to the server the socks client is being forwarded
// to
asio::ip::tcp::socket m_server_connection;
asio::ip::tcp::acceptor m_bind_socket;
asio::ip::udp::socket m_udp_associate;
asio::ip::udp::endpoint m_udp_associate_ep;
asio::ip::udp::endpoint m_udp_from;
std::array<char, 1500> m_udp_buffer;
// receive buffer for data going out, i.e. client -> proxy (us) -> server
char m_out_buffer[65536];
// buffer size
int m_num_out_bytes;
// receive buffer for data coming in, i.e. server -> proxy (us) -> client
char m_in_buffer[65536];
// buffer size
int m_num_in_bytes;
// set to true when shutting down
bool m_close = false;
// the SOCKS protocol version (4 or 5)
const int m_version;
int m_command;
std::array<int, 3>& m_cmd_counts;
std::uint32_t const m_flags;
};
// This is a very simple socks4 and 5 server that only supports a single
// concurrent connection
struct SIMULATOR_DECL socks_server
{
socks_server(asio::io_context& ios, unsigned short listen_port
, int version = 5, std::uint32_t flags = 0);
void stop();
void bind_start_port(int const port) { m_bind_port = port; }
// return the number of CONNECT, BIND and UDP_ASSOCIATE commands the proxy
// has received
std::array<int, 3> cmd_counts() const
{ return m_cmd_counts; }
private:
void on_accept(boost::system::error_code const& ec);
asio::io_context& m_ios;
asio::ip::tcp::acceptor m_listen_socket;
std::shared_ptr<socks_connection> m_conn;
asio::ip::tcp::endpoint m_ep;
int m_bind_port = 2048;
// set to true when shutting down
bool m_close = false;
// the SOCKS protocol version (4 or 5)
const int m_version;
std::array<int, 3> m_cmd_counts;
std::uint32_t const m_flags;
};
}
#ifdef _MSC_VER
#pragma warning(pop)
#endif
#endif
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