// Copyright (c) 2018, The Monero Project
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#pragma once
#include <cstdint>
#include <boost/asio/ip/tcp.hpp>
#include <boost/asio/io_service.hpp>
#include <boost/system/error_code.hpp>
#include <boost/type_traits/integral_constant.hpp>
#include <boost/utility/string_ref.hpp>
#include <memory>
#include <utility>
#include "net/fwd.h"
#include "span.h"
namespace epee
{
namespace net_utils
{
class ipv4_network_address;
}
}
namespace net
{
namespace socks
{
//! Supported socks variants.
enum class version : std::uint8_t
{
v4 = 0,
v4a,
v4a_tor //!< Extensions defined in Tor codebase
};
//! Possible errors with socks communication. Defined in https://www.openssh.com/txt/socks4.protocol
enum class error : int
{
// 0 is reserved for success value
// 1-256 -> reserved for error values from socks server (+1 from wire value).
rejected = 92,
identd_connection,
identd_user,
// Specific to application
bad_read = 257,
bad_write,
unexpected_version
};
/* boost::system::error_code is extended for easier compatibility with
boost::asio errors. If std::error_code is needed (with expect<T> for
instance), then upgrade to boost 1.65+ or use conversion code in
develop branch at boost/system/detail/std_interoperability.hpp */
//! \return boost::system::error_category for net::socks namespace
const boost::system::error_category& error_category() noexcept;
//! \return net::socks::error as a boost::system::error_code.
inline boost::system::error_code make_error_code(error value) noexcept
{
return boost::system::error_code{int(value), socks::error_category()};
}
//! Client support for socks connect and resolve commands.
class client
{
boost::asio::ip::tcp::socket proxy_;
std::uint16_t buffer_size_;
std::uint8_t buffer_[1024];
socks::version ver_;
/*!
Only invoked after `*send(...)` function completes or fails.
`bool(error) == false` indicates success; `self.get()` is always
`this` and allows implementations to skip
`std::enable_shared_from_this<T>` (ASIO callbacks need shared_ptr).
The design saves space and reduces cycles (everything uses moves,
so no atomic operations are ever necessary).
\param error when processing last command (if any).
\param self `shared_ptr<client>` handle to `this`.
*/
virtual void done(boost::system::error_code error, std::shared_ptr<client> self) = 0;
public:
using stream_type = boost::asio::ip::tcp;
// defined in cpp
struct write;
struct read;
struct completed;
/*!
\param proxy ownership is passed into `this`. Does not have to be
in connected state.
\param ver socks version for the connection.
*/
explicit client(stream_type::socket&& proxy, socks::version ver);
client(const client&) = delete;
virtual ~client();
client& operator=(const client&) = delete;
//! \return Ownership of socks client socket object.
stream_type::socket take_socket()
{
return stream_type::socket{std::move(proxy_)};
}
//! \return Socks version.
socks::version socks_version() const noexcept { return ver_; }
//! \return Contents of internal buffer.
epee::span<const std::uint8_t> buffer() const noexcept
{
return {buffer_, buffer_size_};
}
//! \post `buffer.empty()`.
void clear_command() noexcept { buffer_size_ = 0; }
//! Try to set `address` as remote connection request.
bool set_connect_command(const epee::net_utils::ipv4_network_address& address);
//! Try to set `domain` + `port` as remote connection request.
bool set_connect_command(boost::string_ref domain, std::uint16_t port);
//! Try to set `address` as remote Tor hidden service connection request.
bool set_connect_command(const net::tor_address& address);
//! Try to set `domain` as remote DNS A record lookup request.
bool set_resolve_command(boost::string_ref domain);
/*!
Asynchronously connect to `proxy_address` then issue command in
`buffer()`. The `done(...)` method will be invoked upon completion
with `self` and potential `error`s.
\note Must use one of the `self->set_*_command` calls before using
this function.
\param self ownership of object is given to function.
\param proxy_address of the socks server.
\return False if `self->buffer().empty()` (no command set).
*/
static bool connect_and_send(std::shared_ptr<client> self, const stream_type::endpoint& proxy_address);
/*!
Assume existing connection to proxy server; asynchronously issue
command in `buffer()`. The `done(...)` method will be invoked
upon completion with `self` and potential `error`s.
\note Must use one of the `self->set_*_command` calls before using
the function.
\param self ownership of object is given to function.
\return False if `self->buffer().empty()` (no command set).
*/
static bool send(std::shared_ptr<client> self);
};
template<typename Handler>
class connect_client : public client
{
Handler handler_;
virtual void done(boost::system::error_code error, std::shared_ptr<client>) override
{
handler_(error, take_socket());
}
public:
explicit connect_client(stream_type::socket&& proxy, socks::version ver, Handler&& handler)
: client(std::move(proxy), ver), handler_(std::move(handler))
{}
virtual ~connect_client() override {}
};
template<typename Handler>
inline std::shared_ptr<client>
make_connect_client(client::stream_type::socket&& proxy, socks::version ver, Handler handler)
{
return std::make_shared<connect_client<Handler>>(std::move(proxy), ver, std::move(handler));
}
} // socks
} // net
namespace boost
{
namespace system
{
template<>
struct is_error_code_enum<net::socks::error>
: true_type
{};
} // system
} // boost
