/*

Copyright (c) 2007-2018, Arvid Norberg
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in
      the documentation and/or other materials provided with the distribution.
    * Neither the name of the author nor the names of its
      contributors may be used to endorse or promote products derived
      from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.

*/
#include "libtorrent/config.hpp"

#include "libtorrent/aux_/disable_warnings_push.hpp"

#if defined TORRENT_OS2
#include <pthread.h>
#endif

#include <boost/version.hpp>
#include <boost/bind.hpp>

#include "libtorrent/aux_/disable_warnings_pop.hpp"

#include "libtorrent/natpmp.hpp"
#include "libtorrent/io.hpp"
#include "libtorrent/assert.hpp"
#include "libtorrent/enum_net.hpp"
#include "libtorrent/socket_io.hpp"
#include "libtorrent/io_service.hpp"
#include "libtorrent/aux_/time.hpp"
#include "libtorrent/aux_/escape_string.hpp"

#include <boost/asio/ip/host_name.hpp>

//#define NATPMP_LOG

#ifdef NATPMP_LOG
#include <iostream>
#endif

#if defined TORRENT_ASIO_DEBUGGING
#include "libtorrent/debug.hpp"
#endif

using namespace libtorrent;

natpmp::natpmp(io_service& ios
	, portmap_callback_t const& cb, log_callback_t const& lcb)
	: m_callback(cb)
	, m_log_callback(lcb)
	, m_currently_mapping(-1)
	, m_retry_count(0)
	, m_socket(ios)
	, m_send_timer(ios)
	, m_refresh_timer(ios)
	, m_next_refresh(-1)
	, m_disabled(false)
	, m_abort(false)
{
	// unfortunately async operations rely on the storage
	// for this array not to be reallocated, by passing
	// around pointers to its elements. so reserve size for now
	m_mappings.reserve(10);
}

void natpmp::start()
{
	mutex::scoped_lock l(m_mutex);

	error_code ec;
	address gateway = get_default_gateway(lt::get_io_service(m_socket), ec);
	if (ec)
	{
		char msg[200];
		snprintf(msg, sizeof(msg), "failed to find default route: %s"
			, convert_from_native(ec.message()).c_str());
		log(msg, l);
		disable(ec, l);
		return;
	}

	m_disabled = false;

	udp::endpoint nat_endpoint(gateway, 5351);
	if (nat_endpoint == m_nat_endpoint) return;
	m_nat_endpoint = nat_endpoint;

	char msg[200];
	snprintf(msg, sizeof(msg), "found router at: %s"
		, print_address(m_nat_endpoint.address()).c_str());
	log(msg, l);

	m_socket.open(udp::v4(), ec);
	if (ec)
	{
		disable(ec, l);
		return;
	}
	m_socket.bind(udp::endpoint(address_v4::any(), 0), ec);
	if (ec)
	{
		disable(ec, l);
		return;
	}

#if defined TORRENT_ASIO_DEBUGGING
	add_outstanding_async("natpmp::on_reply");
#endif
	m_socket.async_receive_from(boost::asio::buffer(&m_response_buffer[0]
		, sizeof(m_response_buffer))
		, m_remote, boost::bind(&natpmp::on_reply, self(), _1, _2));
	send_get_ip_address_request(l);

	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
		if (i->protocol == none
			|| i->action != mapping_t::action_none)
			continue;
		i->action = mapping_t::action_add;
		update_mapping(i - m_mappings.begin(), l);
	}
}

void natpmp::send_get_ip_address_request(mutex::scoped_lock& l)
{
	using namespace libtorrent::detail;

	char buf[2];
	char* out = buf;
	write_uint8(0, out); // NAT-PMP version
	write_uint8(0, out); // public IP address request opcode
	log("==> get public IP address", l);

	error_code ec;
	m_socket.send_to(boost::asio::buffer(buf, sizeof(buf)), m_nat_endpoint, 0, ec);
}

bool natpmp::get_mapping(int index, int& local_port, int& external_port, int& protocol) const
{
	mutex::scoped_lock l(m_mutex);

	TORRENT_ASSERT(index < int(m_mappings.size()) && index >= 0);
	if (index >= int(m_mappings.size()) || index < 0) return false;
	mapping_t const& m = m_mappings[index];
	if (m.protocol == none) return false;
	local_port = m.local_port;
	external_port = m.external_port;
	protocol = m.protocol;
	return true;
}

void natpmp::log(char const* msg, mutex::scoped_lock& l)
{
	l.unlock();
	m_log_callback(msg);
	l.lock();
}

void natpmp::disable(error_code const& ec, mutex::scoped_lock& l)
{
	m_disabled = true;

	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
		if (i->protocol == none) continue;
		int const proto = i->protocol;
		i->protocol = none;
		int index = i - m_mappings.begin();
		l.unlock();
		m_callback(index, address(), 0, proto, ec);
		l.lock();
	}
	close_impl(l);
}

void natpmp::delete_mapping(int index)
{
	mutex::scoped_lock l(m_mutex);

	TORRENT_ASSERT(index < int(m_mappings.size()) && index >= 0);
	if (index >= int(m_mappings.size()) || index < 0) return;
	mapping_t& m = m_mappings[index];

	if (m.protocol == none) return;
	if (!m.map_sent)
	{
		m.action = mapping_t::action_none;
		m.protocol = none;
		return;
	}

	m.action = mapping_t::action_delete;
	update_mapping(index, l);
}

int natpmp::add_mapping(protocol_type p, int external_port, int local_port)
{
	mutex::scoped_lock l(m_mutex);

	if (m_disabled) return -1;

	std::vector<mapping_t>::iterator i = std::find_if(m_mappings.begin()
		, m_mappings.end(), boost::bind(&mapping_t::protocol, _1) == int(none));
	if (i == m_mappings.end())
	{
		m_mappings.push_back(mapping_t());
		i = m_mappings.end() - 1;
	}
	i->protocol = p;
	i->external_port = external_port;
	i->local_port = local_port;
	i->action = mapping_t::action_add;

	int mapping_index = i - m_mappings.begin();

#ifdef NATPMP_LOG
	time_point now = aux::time_now();
	for (std::vector<mapping_t>::iterator m = m_mappings.begin()
		, end(m_mappings.end()); m != end; ++m)
	{
		std::cout << " ADD MAPPING: " << mapping_index << " [ "
			"proto: " << (i->protocol == none ? "none" : i->protocol == tcp ? "tcp" : "udp")
			<< " port: " << i->external_port
			<< " local-port: " << i->local_port
			<< " action: " << (i->action == mapping_t::action_none ? "none" : i->action == mapping_t::action_add ? "add" : "delete")
			<< " ttl: " << total_seconds(i->expires - now)
			<< " ]" << std::endl;
	}
#endif

	update_mapping(mapping_index, l);
	return mapping_index;
}

void natpmp::try_next_mapping(int i, mutex::scoped_lock& l)
{
#ifdef NATPMP_LOG
	time_point now = aux::time_now();
	for (std::vector<mapping_t>::iterator m = m_mappings.begin()
		, end(m_mappings.end()); m != end; ++m)
	{
		std::cout << "     " << (m - m_mappings.begin()) << " [ "
			"proto: " << (m->protocol == none ? "none" : m->protocol == tcp ? "tcp" : "udp")
			<< " port: " << m->external_port
			<< " local-port: " << m->local_port
			<< " action: " << (m->action == mapping_t::action_none ? "none" : m->action == mapping_t::action_add ? "add" : "delete")
			<< " ttl: " << total_seconds(m->expires - now)
			<< " ]" << std::endl;
	}
#endif
	if (i < int(m_mappings.size()) - 1)
	{
		update_mapping(i + 1, l);
		return;
	}

	std::vector<mapping_t>::iterator m = std::find_if(
		m_mappings.begin(), m_mappings.end()
		, boost::bind(&mapping_t::action, _1) != int(mapping_t::action_none)
		&& boost::bind(&mapping_t::protocol, _1) != int(none));

	if (m == m_mappings.end())
	{
		if (m_abort)
		{
			error_code ec;
			m_send_timer.cancel(ec);
			m_socket.close(ec);
		}
#ifdef NATPMP_LOG
		std::cout << "     done" << (m_abort?" shutting down":"") << std::endl;
#endif
		return;
	}

#ifdef NATPMP_LOG
	std::cout << "     updating " << (m - m_mappings.begin()) << std::endl;
#endif

	update_mapping(m - m_mappings.begin(), l);
}

void natpmp::update_mapping(int i, mutex::scoped_lock& l)
{
	if (i == int(m_mappings.size()))
	{
		if (m_abort)
		{
			error_code ec;
			m_send_timer.cancel(ec);
			m_socket.close(ec);
		}
#ifdef NATPMP_LOG
		std::cout << "     done" << (m_abort?" shutting down":"") << std::endl;
#endif
		return;
	}

	natpmp::mapping_t& m = m_mappings[i];
	if (m.action == mapping_t::action_none
		|| m.protocol == none)
	{
		try_next_mapping(i, l);
		return;
	}

	if (m_currently_mapping == -1)
	{
		// the socket is not currently in use
		// send out a mapping request
		m_retry_count = 0;
		send_map_request(i, l);
	}
}

void natpmp::send_map_request(int i, mutex::scoped_lock& l)
{
	using namespace libtorrent::detail;

	TORRENT_ASSERT(m_currently_mapping == -1
		|| m_currently_mapping == i);
	m_currently_mapping = i;
	mapping_t& m = m_mappings[i];
	TORRENT_ASSERT(m.action != mapping_t::action_none);
	char buf[12];
	char* out = buf;
	write_uint8(0, out); // NAT-PMP version
	write_uint8(m.protocol, out); // map "protocol"
	write_uint16(0, out); // reserved
	write_uint16(m.local_port, out); // private port
	write_uint16(m.external_port, out); // requested public port
	int ttl = m.action == mapping_t::action_add ? 3600 : 0;
	write_uint32(ttl, out); // port mapping lifetime

	char msg[200];
	snprintf(msg, sizeof(msg), "==> port map [ mapping: %d action: %s"
		" proto: %s local: %u external: %u ttl: %u ]"
		, i, m.action == mapping_t::action_add ? "add" : "delete"
		, m.protocol == udp ? "udp" : "tcp"
		, m.local_port, m.external_port, ttl);
	log(msg, l);

	error_code ec;
	m_socket.send_to(boost::asio::buffer(buf, sizeof(buf)), m_nat_endpoint, 0, ec);
	m.map_sent = true;
	m.outstanding_request = true;
	if (m_abort)
	{
		// when we're shutting down, ignore the
		// responses and just remove all mappings
		// immediately
		m_currently_mapping = -1;
		m.action = mapping_t::action_none;
		try_next_mapping(i, l);
	}
	else
	{
#if defined TORRENT_ASIO_DEBUGGING
		add_outstanding_async("natpmp::resend_request");
#endif
		// linear back-off instead of exponential
		++m_retry_count;
		m_send_timer.expires_from_now(milliseconds(250 * m_retry_count), ec);
		m_send_timer.async_wait(boost::bind(&natpmp::resend_request, self(), i, _1));
	}
}

void natpmp::resend_request(int i, error_code const& e)
{
#if defined TORRENT_ASIO_DEBUGGING
	complete_async("natpmp::resend_request");
#endif
	if (e) return;
	mutex::scoped_lock l(m_mutex);
	if (m_currently_mapping != i) return;

	// if we're shutting down, don't retry, just move on
	// to the next mapping
	if (m_retry_count >= 9 || m_abort)
	{
		m_currently_mapping = -1;
		m_mappings[i].action = mapping_t::action_none;
		// try again in two hours
		m_mappings[i].expires = aux::time_now() + hours(2);
		try_next_mapping(i, l);
		return;
	}
	send_map_request(i, l);
}

void natpmp::on_reply(error_code const& e
	, std::size_t bytes_transferred)
{
	mutex::scoped_lock l(m_mutex);

#if defined TORRENT_ASIO_DEBUGGING
	complete_async("natpmp::on_reply");
#endif

	using namespace libtorrent::detail;
	if (e)
	{
		char msg[200];
		snprintf(msg, sizeof(msg), "error on receiving reply: %s"
			, convert_from_native(e.message()).c_str());
		log(msg, l);
		return;
	}

	if (m_abort) return;

#if defined TORRENT_ASIO_DEBUGGING
	add_outstanding_async("natpmp::on_reply");
#endif
	// make a copy of the response packet buffer
	// to avoid overwriting it in the next receive call
	char msg_buf[sizeof(m_response_buffer)];
	memcpy(msg_buf, m_response_buffer, bytes_transferred);

	m_socket.async_receive_from(boost::asio::buffer(&m_response_buffer[0]
		, sizeof(m_response_buffer))
		, m_remote, boost::bind(&natpmp::on_reply, self(), _1, _2));

	// simulate packet loss
/*
	if ((random() % 2) == 0)
	{
		log(" simulating drop", l);
		return;
	}
*/
	if (m_remote != m_nat_endpoint)
	{
		char msg[200];
		snprintf(msg, sizeof(msg), "received packet from wrong IP: %s"
			, print_endpoint(m_remote).c_str());
		log(msg, l);
		return;
	}

	error_code ec;
	m_send_timer.cancel(ec);

	if (bytes_transferred < 12)
	{
		char msg[200];
		snprintf(msg, sizeof(msg), "received packet of invalid size: %d", int(bytes_transferred));
		log(msg, l);
		return;
	}

	char* in = msg_buf;
	int version = read_uint8(in);
	int cmd = read_uint8(in);
	int result = read_uint16(in);
	int time = read_uint32(in);

	if (cmd == 128)
	{
		// public IP request response
		m_external_ip = read_v4_address(in);

		char msg[200];
		snprintf(msg, sizeof(msg), "<== public IP address [ %s ]", print_address(m_external_ip).c_str());
		log(msg, l);
		return;

	}

	if (bytes_transferred != 16)
	{
		char msg[200];
		snprintf(msg, sizeof(msg), "received packet of invalid size: %d", int(bytes_transferred));
		log(msg, l);
		return;
	}

	int private_port = read_uint16(in);
	int public_port = read_uint16(in);
	int lifetime = read_uint32(in);

	(void)time; // to remove warning

	int protocol = (cmd - 128 == 1)?udp:tcp;

	char msg[200];
	int num_chars = snprintf(msg, sizeof(msg), "<== port map ["
		" protocol: %s local: %u external: %u ttl: %u ]"
		, (cmd - 128 == 1 ? "udp" : "tcp")
		, private_port, public_port, lifetime);

	if (version != 0)
	{
		snprintf(msg + num_chars, sizeof(msg) - num_chars, "unexpected version: %u"
			, version);
		log(msg, l);
	}

	mapping_t* m = 0;
	int index = -1;
	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
		if (private_port != i->local_port) continue;
		if (protocol != i->protocol) continue;
		if (!i->map_sent) continue;
		if (!i->outstanding_request) continue;
		m = &*i;
		index = i - m_mappings.begin();
		break;
	}

	if (m == 0)
	{
		snprintf(msg + num_chars, sizeof(msg) - num_chars, " not found in map table");
		log(msg, l);
		return;
	}
	m->outstanding_request = false;

	log(msg, l);

	if (public_port == 0 || lifetime == 0)
	{
		// this means the mapping was
		// successfully closed
		m->protocol = none;
	}
	else
	{
		m->expires = aux::time_now() + seconds(int(lifetime * 0.7f));
		m->external_port = public_port;
	}

	if (result != 0)
	{
		// TODO: 3 it would be nice to have a separate NAT-PMP error category
		errors::error_code_enum errors[] =
		{
			errors::unsupported_protocol_version,
			errors::natpmp_not_authorized,
			errors::network_failure,
			errors::no_resources,
			errors::unsupported_opcode,
		};
		errors::error_code_enum ev = errors::no_error;
		if (result >= 1 && result <= 5) ev = errors[result - 1];

		m->expires = aux::time_now() + hours(2);
		int const proto = m->protocol;
		l.unlock();
		m_callback(index, address(), 0, proto, ev);
		l.lock();
	}
	else if (m->action == mapping_t::action_add)
	{
		int const proto = m->protocol;
		l.unlock();
		m_callback(index, m_external_ip, m->external_port, proto
			, errors::no_error);
		l.lock();
	}

	m_currently_mapping = -1;
	m->action = mapping_t::action_none;
	m_send_timer.cancel(ec);
	update_expiration_timer(l);
	try_next_mapping(index, l);
}

void natpmp::update_expiration_timer(mutex::scoped_lock& l)
{
	if (m_abort) return;

	time_point now = aux::time_now() + milliseconds(100);
#ifdef NATPMP_LOG
	std::cout << time_now_string() << " update_expiration_timer " << std::endl;
	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
	std::cout << "     " << (i - m_mappings.begin()) << " [ "
			"proto: " << (i->protocol == none ? "none" : i->protocol == tcp ? "tcp" : "udp")
			<< " port: " << i->external_port
			<< " local-port: " << i->local_port
			<< " action: " << (i->action == mapping_t::action_none ? "none" : i->action == mapping_t::action_add ? "add" : "delete")
			<< " ttl: " << total_seconds(i->expires - now)
			<< " ]" << std::endl;
	}
#endif
	time_point min_expire = now + seconds(3600);
	int min_index = -1;
	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
		if (i->protocol == none
			|| i->action != mapping_t::action_none) continue;
		int index = i - m_mappings.begin();
		if (i->expires < now)
		{
			char msg[200];
			snprintf(msg, sizeof(msg), "mapping %u expired", index);
			log(msg, l);
			i->action = mapping_t::action_add;
			if (m_next_refresh == index) m_next_refresh = -1;
			update_mapping(index, l);
		}
		else if (i->expires < min_expire)
		{
			min_expire = i->expires;
			min_index = index;
		}
	}

	// this is already the mapping we're waiting for
	if (m_next_refresh == min_index) return;

	if (min_index >= 0)
	{
#ifdef NATPMP_LOG
	std::cout << time_now_string() << " next expiration ["
			" i: " << min_index
			<< " ttl: " << total_seconds(min_expire - aux::time_now())
			<< " ]" << std::endl;
#endif
		error_code ec;
		if (m_next_refresh >= 0) m_refresh_timer.cancel(ec);

#if defined TORRENT_ASIO_DEBUGGING
		add_outstanding_async("natpmp::mapping_expired");
#endif
		m_refresh_timer.expires_from_now(min_expire - now, ec);
		m_refresh_timer.async_wait(boost::bind(&natpmp::mapping_expired, self(), _1, min_index));
		m_next_refresh = min_index;
	}
}

void natpmp::mapping_expired(error_code const& e, int i)
{
#if defined TORRENT_ASIO_DEBUGGING
	complete_async("natpmp::mapping_expired");
#endif
	if (e) return;
	mutex::scoped_lock l(m_mutex);
	char msg[200];
	snprintf(msg, sizeof(msg), "mapping %u expired", i);
	log(msg, l);
	m_mappings[i].action = mapping_t::action_add;
	if (m_next_refresh == i) m_next_refresh = -1;
	update_mapping(i, l);
}

void natpmp::close()
{
	mutex::scoped_lock l(m_mutex);
	close_impl(l);
}

void natpmp::close_impl(mutex::scoped_lock& l)
{
	m_abort = true;
	log("closing", l);
#ifdef NATPMP_LOG
	std::cout << time_now_string() << " close" << std::endl;
	time_point now = aux::time_now();
#endif
	if (m_disabled) return;
	for (std::vector<mapping_t>::iterator i = m_mappings.begin()
		, end(m_mappings.end()); i != end; ++i)
	{
#ifdef NATPMP_LOG
	std::cout << "     " << (i - m_mappings.begin()) << " [ "
			"proto: " << (i->protocol == none ? "none" : i->protocol == tcp ? "tcp" : "udp")
			<< " port: " << i->external_port
			<< " local-port: " << i->local_port
			<< " action: " << (i->action == mapping_t::action_none ? "none" : i->action == mapping_t::action_add ? "add" : "delete")
			<< " ttl: " << total_seconds(i->expires - now)
			<< " ]" << std::endl;
#endif
		if (i->protocol == none) continue;
		i->action = mapping_t::action_delete;
	}
	error_code ec;
	m_refresh_timer.cancel(ec);
	m_currently_mapping = -1;
	update_mapping(0, l);
}

