libtorrent/test/test_tracker.cpp

/*

Copyright (c) 2011-2022, Arvid Norberg
Copyright (c) 2015, Mikhail Titov
Copyright (c) 2016-2018, 2020-2021, Alden Torres
Copyright (c) 2016, terry zhao
Copyright (c) 2017-2018, Steven Siloti
Copyright (c) 2018, d-komarov
Copyright (c) 2020-2021, Paul-Louis Ageneau
All rights reserved.

You may use, distribute and modify this code under the terms of the BSD license,
see LICENSE file.
*/

#include "test.hpp"
#include "setup_transfer.hpp"  // for supports_ipv6
#include "test_utils.hpp"
#include "udp_tracker.hpp"
#include "settings.hpp"
#include "test_utils.hpp"
#include "libtorrent/alert.hpp"
#include "libtorrent/peer_info.hpp" // for peer_list_entry
#include "libtorrent/alert_types.hpp"
#include "libtorrent/session.hpp"
#include "libtorrent/session_params.hpp"
#include "libtorrent/error_code.hpp"
#include "libtorrent/aux_/tracker_manager.hpp"
#include "libtorrent/aux_/http_tracker_connection.hpp" // for parse_tracker_response
#include "libtorrent/aux_/websocket_tracker_connection.hpp" // for parse_websocket_tracker_response
#include "libtorrent/torrent_info.hpp"
#include "libtorrent/announce_entry.hpp"
#include "libtorrent/aux_/path.hpp"
#include "libtorrent/aux_/socket_io.hpp"

#include <array>
#include <iostream>

using namespace lt;

// TODO: test scrape requests
// TODO: test parse tracker-id
// TODO: test parse failure-reason
// TODO: test all failure paths, including
//   invalid bencoding
//   not a dictionary
//   no files entry in scrape response
//   no info-hash entry in scrape response
//   malformed peers in peer list of dictionaries
//   uneven number of bytes in peers and peers6 string responses

TORRENT_TEST(parse_hostname_peers)
{
	char const response[] = "d5:peersld7:peer id20:aaaaaaaaaaaaaaaaaaaa"
		"2:ip13:test_hostname4:porti1000eed"
		"7:peer id20:bbbbabaababababababa2:ip12:another_host4:porti1001eeee";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers.size(), 2);
	if (resp.peers.size() == 2)
	{
		aux::peer_entry const& e0 = resp.peers[0];
		aux::peer_entry const& e1 = resp.peers[1];
		TEST_EQUAL(e0.hostname, "test_hostname");
		TEST_EQUAL(e0.port, 1000);
		TEST_EQUAL(e0.pid, peer_id("aaaaaaaaaaaaaaaaaaaa"));

		TEST_EQUAL(e1.hostname, "another_host");
		TEST_EQUAL(e1.port, 1001);
		TEST_EQUAL(e1.pid, peer_id("bbbbabaababababababa"));
	}
}

TORRENT_TEST(parse_peers4)
{
	char const response[] = "d5:peers12:\x01\x02\x03\x04\x30\x10"
		"\x09\x08\x07\x06\x20\x10" "e";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers4.size(), 2);
	if (resp.peers4.size() == 2)
	{
		aux::ipv4_peer_entry const& e0 = resp.peers4[0];
		aux::ipv4_peer_entry const& e1 = resp.peers4[1];
		TEST_CHECK(e0.ip == addr4("1.2.3.4").to_bytes());
		TEST_EQUAL(e0.port, 0x3010);

		TEST_CHECK(e1.ip == addr4("9.8.7.6").to_bytes());
		TEST_EQUAL(e1.port, 0x2010);
	}
}

TORRENT_TEST(parse_peers4_invalid_length)
{
	std::string response = "d5:peers7:";
	response.append("\x01\x02\x03\x04\x30\x10\x01", 7);
	response += 'e';

	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response, ec, {}, sha1_hash());

	TEST_EQUAL(ec, errors::invalid_peers_entry);
	TEST_EQUAL(resp.peers4.size(), 0);
}

TORRENT_TEST(parse_peers6)
{
	std::string response = "d6:peers636:";
	auto const ip0 = addr6("2001:db8::1").to_bytes();
	response.append(reinterpret_cast<char const*>(ip0.data()), ip0.size());
	response.push_back(char(0x30));
	response.push_back(char(0x10));
	auto const ip1 = addr6("2001:db8::2").to_bytes();
	response.append(reinterpret_cast<char const*>(ip1.data()), ip1.size());
	response.push_back(char(0x20));
	response.push_back(char(0x10));
	response += 'e';

	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers6.size(), 2);
	if (resp.peers6.size() == 2)
	{
		aux::ipv6_peer_entry const& e0 = resp.peers6[0];
		aux::ipv6_peer_entry const& e1 = resp.peers6[1];
		TEST_CHECK(e0.ip == addr6("2001:db8::1").to_bytes());
		TEST_EQUAL(e0.port, 0x3010);

		TEST_CHECK(e1.ip == addr6("2001:db8::2").to_bytes());
		TEST_EQUAL(e1.port, 0x2010);
	}
}

TORRENT_TEST(parse_peers6_invalid_length)
{
	std::string response = "d6:peers619:";
	response.append(19, '\1');
	response += 'e';

	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response, ec, {}, sha1_hash());

	TEST_EQUAL(ec, errors::invalid_peers_entry);
	TEST_EQUAL(resp.peers6.size(), 0);
}

#if TORRENT_USE_I2P
TORRENT_TEST(parse_i2p_peers)
{
	// d8:completei8e10:incompletei4e8:intervali3600e5:peers352: ...
	std::uint8_t const response[] = { 0x64, 0x38, 0x3a, 0x63, 0x6f, 0x6d,
		0x70, 0x6c, 0x65, 0x74, 0x65, 0x69, 0x38, 0x65, 0x31, 0x30,
		0x3a, 0x69, 0x6e, 0x63, 0x6f, 0x6d, 0x70, 0x6c, 0x65, 0x74,
		0x65, 0x69, 0x34, 0x65, 0x38, 0x3a, 0x69, 0x6e, 0x74, 0x65,
		0x72, 0x76, 0x61, 0x6c, 0x69, 0x33, 0x36, 0x30, 0x30, 0x65,
		0x35, 0x3a, 0x70, 0x65, 0x65, 0x72, 0x73, 0x33, 0x35, 0x32,
		0x3a, 0xb1, 0x84, 0xe0, 0x96, 0x1f, 0xdb, 0xf2, 0xc9, 0xb0,
		0x53, 0x9a, 0x31, 0xa5, 0x35, 0xcd, 0xe8, 0x59, 0xa0, 0x7c,
		0xcd, 0xf2, 0x7c, 0x81, 0x81, 0x02, 0x11, 0x7b, 0xb4, 0x2a,
		0xd1, 0x20, 0x87, 0xd6, 0x1b, 0x06, 0x4c, 0xbb, 0x4c, 0x4e,
		0x30, 0xf9, 0xa3, 0x5d, 0x58, 0xa0, 0xa5, 0x10, 0x48, 0xfa,
		0x9b, 0x3b, 0x10, 0x86, 0x43, 0x5c, 0x2e, 0xa2, 0xa6, 0x22,
		0x31, 0xd0, 0x63, 0x6a, 0xfb, 0x4f, 0x25, 0x5b, 0xe2, 0x29,
		0xbc, 0xcc, 0xa0, 0x1a, 0x0a, 0x30, 0x45, 0x32, 0xa1, 0xc8,
		0x49, 0xf7, 0x9e, 0x03, 0xfd, 0x34, 0x80, 0x9a, 0x5b, 0xe9,
		0x78, 0x04, 0x48, 0x4e, 0xbd, 0xc0, 0x5c, 0xdd, 0x4f, 0xf8,
		0xbd, 0xc8, 0x4c, 0x4b, 0xcc, 0xf6, 0x25, 0x1b, 0xb3, 0x4d,
		0xc0, 0x91, 0xb1, 0x4b, 0xb6, 0xbd, 0x95, 0xb7, 0x8e, 0x88,
		0x79, 0xa8, 0xaa, 0x83, 0xa5, 0x7e, 0xec, 0x17, 0x60, 0x8d,
		0x1d, 0xe2, 0xbe, 0x16, 0x35, 0x83, 0x25, 0xee, 0xe4, 0xd5,
		0xbe, 0x54, 0x7b, 0xc8, 0x00, 0xdc, 0x5d, 0x56, 0xc7, 0x29,
		0xd2, 0x1e, 0x6d, 0x7a, 0xfb, 0xfc, 0xef, 0x36, 0x05, 0x8a,
		0xd0, 0xa7, 0x05, 0x4c, 0x11, 0xd5, 0x50, 0xe6, 0x2d, 0x7b,
		0xe0, 0x7d, 0x84, 0xda, 0x47, 0x48, 0x9d, 0xf9, 0x77, 0xa2,
		0xc7, 0x78, 0x90, 0xa4, 0xb5, 0x05, 0xf4, 0x95, 0xea, 0x36,
		0x7b, 0x92, 0x8c, 0x5b, 0xf7, 0x8b, 0x18, 0x94, 0x2c, 0x2f,
		0x88, 0xcf, 0xf8, 0xec, 0x5c, 0x52, 0xa8, 0x98, 0x8f, 0xd1,
		0xd3, 0xf0, 0xd8, 0x63, 0x19, 0x73, 0x33, 0xd7, 0xeb, 0x1f,
		0x87, 0x1c, 0x9f, 0x5b, 0xce, 0xe4, 0xd0, 0x15, 0x4e, 0x38,
		0xb7, 0xe3, 0xbd, 0x93, 0x64, 0xe2, 0x15, 0x3d, 0xfc, 0x56,
		0x4f, 0xd4, 0x19, 0x62, 0xe0, 0xb7, 0x59, 0x24, 0xff, 0x7f,
		0x32, 0xdf, 0x56, 0xa5, 0x62, 0x42, 0x87, 0xa3, 0x04, 0xec,
		0x09, 0x0a, 0x5b, 0x90, 0x48, 0x57, 0xc3, 0x32, 0x5f, 0x87,
		0xeb, 0xfb, 0x08, 0x69, 0x6f, 0xa9, 0x46, 0x46, 0xa9, 0x54,
		0x67, 0xec, 0x7b, 0x15, 0xc9, 0x68, 0x6b, 0x01, 0xb8, 0x10,
		0x59, 0x53, 0x9c, 0xe6, 0x1b, 0x2e, 0x70, 0x72, 0x6e, 0x82,
		0x7b, 0x03, 0xbc, 0xf2, 0x26, 0x9b, 0xb3, 0x91, 0xaa, 0xf1,
		0xba, 0x62, 0x12, 0xbb, 0x74, 0x4b, 0x70, 0x44, 0x74, 0x19,
		0xb2, 0xa1, 0x68, 0xd2, 0x30, 0xd6, 0xa5, 0x1b, 0xd9, 0xea,
		0x4d, 0xdb, 0x81, 0x8e, 0x66, 0xbf, 0x4d, 0x6c, 0x32, 0x66,
		0xc2, 0x8a, 0x22, 0x6b, 0x47, 0xc1, 0xd1, 0x52, 0x61, 0x66,
		0xa0, 0x75, 0xab, 0x65 };
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(
		{ reinterpret_cast<char const*>(response), sizeof(response) }
		, ec, aux::tracker_request::i2p, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.i2p_peers.size(), 11);

	if (resp.i2p_peers.size() == 11)
	{
		bdecode_node decoded;
		error_code decode_ec;
		int const decode_result = bdecode(reinterpret_cast<char const*>(response),
			reinterpret_cast<char const*>(response + sizeof(response)),
			decoded,
			decode_ec);
		TEST_EQUAL(decode_ec, error_code());
		TEST_EQUAL(decode_result, 0);

		bdecode_node const peers = decoded.dict_find_string("peers");
		TEST_CHECK(peers);
		if (peers)
		{
			TEST_EQUAL(peers.string_length(), 11 * int(sha256_hash::size()));
			TEST_CHECK(resp.i2p_peers[0].destination == sha256_hash(peers.string_ptr()));
			TEST_CHECK(resp.i2p_peers[10].destination
				== sha256_hash(peers.string_ptr() + 10 * sha256_hash::size()));
		}
	}
}

TORRENT_TEST(parse_i2p_peers_invalid_length)
{
	std::string response = "d5:peers33:";
	response.append(33, '\1');
	response += 'e';

	error_code ec;
	aux::tracker_response resp =
		aux::parse_tracker_response(response, ec, aux::tracker_request::i2p, sha1_hash());

	TEST_EQUAL(ec, errors::invalid_peers_entry);
	TEST_EQUAL(resp.i2p_peers.size(), 0);
}
#endif // TORRENT_USE_I2P

TORRENT_TEST(parse_interval)
{
	char const response[] = "d8:intervali1042e12:min intervali10e5:peers0:e";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers.size(), 0);
	TEST_EQUAL(resp.peers4.size(), 0);
	TEST_EQUAL(resp.interval.count(), 1042);
	TEST_EQUAL(resp.min_interval.count(), 10);
}

TORRENT_TEST(parse_warning)
{
	char const response[] = "d5:peers0:15:warning message12:test messagee";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers.size(), 0);
	TEST_EQUAL(resp.warning_message, "test message");
}

TORRENT_TEST(parse_failure_reason)
{
	char const response[] = "d5:peers0:14:failure reason12:test messagee";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, errors::tracker_failure);
	TEST_EQUAL(resp.peers.size(), 0);
	TEST_EQUAL(resp.failure_reason, "test message");
}

TORRENT_TEST(parse_scrape_response)
{
	char const response[] = "d5:filesd20:aaaaaaaaaaaaaaaaaaaad"
		"8:completei1e10:incompletei2e10:downloadedi3e11:downloadersi6eeee";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, aux::tracker_request::scrape_request, sha1_hash("aaaaaaaaaaaaaaaaaaaa"));

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.complete, 1);
	TEST_EQUAL(resp.incomplete, 2);
	TEST_EQUAL(resp.downloaded, 3);
	TEST_EQUAL(resp.downloaders, 6);
}

TORRENT_TEST(parse_scrape_response_with_zero)
{
	char const response[] = "d5:filesd20:aaa\0aaaaaaaaaaaaaaaad"
		"8:completei4e10:incompletei5e10:downloadedi6eeee";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, aux::tracker_request::scrape_request, sha1_hash("aaa\0aaaaaaaaaaaaaaaa"));

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.complete, 4);
	TEST_EQUAL(resp.incomplete, 5);
	TEST_EQUAL(resp.downloaded, 6);
	TEST_EQUAL(resp.downloaders, -1);
}

TORRENT_TEST(parse_external_ip)
{
	char const response[] = "d5:peers0:11:external ip4:\x01\x02\x03\x04" "e";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers.size(), 0);
	TEST_EQUAL(resp.external_ip, addr4("1.2.3.4"));
}

TORRENT_TEST(parse_external_ip6)
{
	char const response[] = "d5:peers0:11:external ip"
		"16:\xf1\x02\x03\x04\0\0\0\0\0\0\0\0\0\0\xff\xff" "e";
	error_code ec;
	aux::tracker_response resp = aux::parse_tracker_response(response
		, ec, {}, sha1_hash());

	TEST_EQUAL(ec, error_code());
	TEST_EQUAL(resp.peers.size(), 0);
	TEST_EQUAL(resp.external_ip, addr6("f102:0304::ffff"));
}

namespace {
aux::peer_entry extract_peer(char const* peer_field, error_code expected_ec, bool expected_ret)
{
	error_code ec;
	aux::peer_entry result;
	bdecode_node n;
	bdecode(peer_field, peer_field + strlen(peer_field)
		, n, ec, nullptr, 1000, 1000);
	TEST_CHECK(!ec);
	bool ret = aux::extract_peer_info(n, result, ec);
	TEST_EQUAL(expected_ret, ret);
	TEST_EQUAL(expected_ec, ec);
	return result;
}
} // anonymous namespace

TORRENT_TEST(extract_peer)
{
	aux::peer_entry result = extract_peer("d7:peer id20:abababababababababab2:ip4:abcd4:porti1337ee"
		, error_code(), true);
	TEST_EQUAL(result.hostname, "abcd");
	TEST_EQUAL(result.pid, peer_id("abababababababababab"));
	TEST_EQUAL(result.port, 1337);
}

TORRENT_TEST(extract_peer_hostname)
{
	aux::peer_entry result = extract_peer("d2:ip11:example.com4:porti1ee"
		, error_code(), true);
	TEST_EQUAL(result.hostname, "example.com");
	TEST_EQUAL(result.pid, peer_id::min());
	TEST_EQUAL(result.port, 1);
}

TORRENT_TEST(extract_peer_not_a_dictionary)
{
	// not a dictionary
	extract_peer("2:ip11:example.com", errors::invalid_peer_dict, false);
}

TORRENT_TEST(extract_peer_missing_ip)
{
	// missing IP
	extract_peer(
		"d7:peer id20:abababababababababab4:porti1337ee", errors::invalid_tracker_response, false);
}

TORRENT_TEST(extract_peer_missing_port)
{
	// missing port
	extract_peer(
		"d7:peer id20:abababababababababab2:ip4:abcde", errors::invalid_tracker_response, false);
}

TORRENT_TEST(extract_peer_negative_port)
{
	extract_peer("d2:ip11:example.com4:porti-1ee", errors::invalid_tracker_response, false);
}

TORRENT_TEST(extract_peer_port_overflow)
{
	extract_peer("d2:ip11:example.com4:porti65536ee", errors::invalid_tracker_response, false);
}

namespace {

bool connect_alert(lt::alert const* a, tcp::endpoint& ep)
{
	if (peer_connect_alert const* pc = alert_cast<peer_connect_alert>(a))
	{
		if (auto i = std::get_if<peer_alert::ip_endpoint>(&pc->ep))
		{
			ep = *i;
			return true;
		}
	}
	return false;
}

void test_udp_tracker(std::string const& iface, address tracker, tcp::endpoint const& expected_peer)
{
	using namespace std::placeholders;

	int const udp_port = start_udp_tracker(tracker);

	int prev_udp_announces = num_udp_announces();

	settings_pack pack = settings();
	pack.set_bool(settings_pack::announce_to_all_trackers, true);
	pack.set_bool(settings_pack::announce_to_all_tiers, true);
	pack.set_int(settings_pack::alert_queue_size, 10000);

	auto s = std::make_unique<lt::session>(pack);

	error_code ec;
	remove_all("tmp1_tracker", ec);
	create_directory("tmp1_tracker", ec);
	ofstream file(combine_path("tmp1_tracker", "temporary").c_str());
	add_torrent_params addp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	char tracker_url[200];
	std::snprintf(tracker_url, sizeof(tracker_url), "udp://%s:%d/announce", iface.c_str(), udp_port);
	addp.trackers.push_back(tracker_url);

	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.flags |= torrent_flags::seed_mode;
	addp.save_path = "tmp1_tracker";
	torrent_handle h = s->add_torrent(addp);

	tcp::endpoint peer_ep;
	for (int i = 0; i < 50; ++i)
	{
		print_alerts(*s, "s", false, false, std::bind(&connect_alert, _1, std::ref(peer_ep)));

		if (num_udp_announces() == prev_udp_announces + 2)
			break;

		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	// expect two announces, one each for v1 and v2
	TEST_EQUAL(num_udp_announces(), prev_udp_announces + 2);

	// if we remove the torrent before it has received the response from the
	// tracker, it won't announce again to stop. So, wait a bit before removing.
	std::this_thread::sleep_for(lt::milliseconds(1000));

	s->remove_torrent(h);

	for (int i = 0; i < 50; ++i)
	{
		print_alerts(*s, "s", true, false, std::bind(&connect_alert, _1, std::ref(peer_ep)));
		if (num_udp_announces() == prev_udp_announces + 4)
			break;

		std::this_thread::sleep_for(lt::milliseconds(100));
	}

	std::printf("peer_ep: %s expected: %s\n"
		, aux::print_endpoint(peer_ep).c_str()
		, aux::print_endpoint(expected_peer).c_str());
	TEST_CHECK(peer_ep == expected_peer);
	std::printf("destructing session\n");

	s.reset();
	std::printf("done\n");

	// we should have announced the stopped event now
	TEST_EQUAL(num_udp_announces(), prev_udp_announces + 4);

	stop_udp_tracker();
}

} // anonymous namespace

TORRENT_TEST(udp_tracker_v4)
{
	// if the machine running the test doesn't have an actual IPv4 connection
	// the test would fail with any other address than loopback (because it
	// would be unreachable). This is true for some CI's, running containers
	// without an internet connection
	test_udp_tracker("127.0.0.1", address_v4::any(), ep("127.0.0.2", 1337));
}

TORRENT_TEST(udp_tracker_v6)
{
	if (supports_ipv6())
	{
		// if the machine running the test doesn't have an actual IPv6 connection
		// the test would fail with any other address than loopback (because it
		// would be unreachable)
		test_udp_tracker("[::1]", address_v6::any(), ep("::1", 1337));
	}
}

TORRENT_TEST(http_peers)
{
	int const http_port = start_web_server();

	settings_pack pack = settings();
	pack.set_bool(settings_pack::announce_to_all_trackers, true);
	pack.set_bool(settings_pack::announce_to_all_tiers, false);
	pack.set_int(settings_pack::tracker_completion_timeout, 2);
	pack.set_int(settings_pack::tracker_receive_timeout, 1);
	pack.set_str(settings_pack::listen_interfaces, test_listen_interface());

	auto s = std::make_unique<lt::session>(pack);

	error_code ec;
	remove_all("tmp2_tracker", ec);
	create_directory("tmp2_tracker", ec);
	ofstream file(combine_path("tmp2_tracker", "temporary").c_str());
	add_torrent_params addp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	char tracker_url[200];
	std::snprintf(tracker_url, sizeof(tracker_url), "http://127.0.0.1:%d/announce"
		, http_port);
	addp.trackers.push_back(tracker_url);

	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.flags |= torrent_flags::seed_mode;
	addp.save_path = "tmp2_tracker";
	torrent_handle h = s->add_torrent(addp);

	lt::torrent_status status = h.status();
	TEST_CHECK(status.current_tracker.empty());

	// wait to hit the tracker
	wait_for_alert(*s, tracker_reply_alert::alert_type, "s");

	status = h.status();
	TEST_CHECK(!status.current_tracker.empty());
	TEST_EQUAL(status.current_tracker, tracker_url);

	// we expect to have certain peers in our peer list now
	// these peers are hard coded in web_server.py
	h.save_resume_data();
	alert const* a = wait_for_alert(*s, save_resume_data_alert::alert_type);

	TEST_CHECK(a);
	save_resume_data_alert const* ra = alert_cast<save_resume_data_alert>(a);
	TEST_CHECK(ra);
	if (ra)
	{
		std::set<tcp::endpoint> expected_peers;
		expected_peers.insert(ep("65.65.65.65", 16962));
		expected_peers.insert(ep("67.67.67.67", 17476));
		expected_peers.insert(ep("4545:4545:4545:4545:4545:4545:4545:4545", 17990));
		for (auto const& ip : ra->params.peers)
		{
			TEST_EQUAL(expected_peers.count(ip), 1);
		}
	}

	std::printf("destructing session\n");
	s.reset();
	std::printf("done\n");

	std::printf("stop_web_server\n");
	stop_web_server();
	std::printf("done\n");
}

TORRENT_TEST(current_tracker)
{
	// use a invalid tracker port
	int http_port = 39527;

	settings_pack pack = settings();
	pack.set_bool(settings_pack::announce_to_all_trackers, true);
	pack.set_bool(settings_pack::announce_to_all_tiers, false);
	pack.set_int(settings_pack::tracker_completion_timeout, 2);
	pack.set_int(settings_pack::tracker_receive_timeout, 1);
	pack.set_str(settings_pack::listen_interfaces, test_listen_interface());

	auto s = std::make_unique<lt::session>(pack);

	error_code ec;
	remove_all("tmp3_tracker", ec);
	create_directory("tmp3_tracker", ec);
	ofstream file(combine_path("tmp3_tracker", "temporary").c_str());
	add_torrent_params addp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	char tracker_url[200];
	std::snprintf(tracker_url, sizeof(tracker_url), "http://127.0.0.1:%d/announce"
		, http_port);
	addp.trackers.push_back(tracker_url);

	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.flags |= torrent_flags::seed_mode;
	addp.save_path = "tmp3_tracker";
	torrent_handle h = s->add_torrent(addp);

	lt::torrent_status status = h.status();
	TEST_CHECK(status.current_tracker.empty());

	// wait to hit the tracker announce
	wait_for_alert(*s, tracker_announce_alert::alert_type, "s");

	status = h.status();
	TEST_CHECK(status.current_tracker.empty());

	// wait to hit the tracker error
	wait_for_alert(*s, tracker_error_alert::alert_type, "s");

	status = h.status();
	TEST_CHECK(status.current_tracker.empty());

	std::printf("destructing session\n");
	s.reset();
	std::printf("done\n");
}

#if TORRENT_USE_RTC
TORRENT_TEST(parse_websocket_tracker_response)
{
	char const response[] = R"({"complete":1,"incomplete":0,"action":"announce","interval":120,"info_hash":"xxxxxxxxxxxxxxxxxxxx"})";

	error_code ec;
	auto ret = aux::parse_websocket_tracker_response({response, long(std::strlen(response))}, ec);

	TEST_EQUAL(ec, error_code{});
	TEST_CHECK(std::holds_alternative<aux::websocket_tracker_response>(ret));

	if(std::holds_alternative<aux::websocket_tracker_response>(ret))
	{
		auto parsed = std::get<aux::websocket_tracker_response>(ret);

		TEST_EQUAL(std::string(parsed.info_hash.data(), parsed.info_hash.size()), "xxxxxxxxxxxxxxxxxxxx");
		TEST_CHECK(!parsed.offer);
		TEST_CHECK(!parsed.answer);
		TEST_CHECK(parsed.resp);

		if (parsed.resp)
		{
			TEST_EQUAL(parsed.resp->interval.count(), 120);
			TEST_EQUAL(parsed.resp->complete, 1);
			TEST_EQUAL(parsed.resp->incomplete, 0);
			TEST_EQUAL(parsed.resp->downloaded, -1);
		}
	}
}

TORRENT_TEST(parse_websocket_tracker_response_offer)
{
	char const response[] = R"({"action":"announce","offer":{"type":"offer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})";

	error_code ec;
	auto ret = aux::parse_websocket_tracker_response({response, long(std::strlen(response))}, ec);

	TEST_EQUAL(ec, error_code{});
	TEST_CHECK(std::holds_alternative<aux::websocket_tracker_response>(ret));

	if(std::holds_alternative<aux::websocket_tracker_response>(ret))
	{
		auto parsed = std::get<aux::websocket_tracker_response>(ret);

		TEST_EQUAL(std::string(parsed.info_hash.data(), parsed.info_hash.size()), "xxxxxxxxxxxxxxxxxxxx");
		TEST_CHECK(!parsed.resp);
		TEST_CHECK(!parsed.answer);
		TEST_CHECK(parsed.offer);

		if (parsed.offer)
		{
			TEST_EQUAL(std::string(parsed.offer->id.data(), parsed.offer->id.size()), "yyyyyyyyyyyyyyyy");
			TEST_EQUAL(parsed.offer->sdp, "SDP\r\n");
		}
	}
}

TORRENT_TEST(parse_websocket_tracker_response_answer)
{
	char const response[] = R"({"action":"announce","answer":{"type":"answer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})";

	error_code ec;
	auto ret = aux::parse_websocket_tracker_response({response, long(std::strlen(response))}, ec);

	TEST_EQUAL(ec, error_code{});
	TEST_CHECK(std::holds_alternative<aux::websocket_tracker_response>(ret));

	if(std::holds_alternative<aux::websocket_tracker_response>(ret))
	{
		auto parsed = std::get<aux::websocket_tracker_response>(ret);

		TEST_EQUAL(std::string(parsed.info_hash.data(), parsed.info_hash.size()), "xxxxxxxxxxxxxxxxxxxx");
		TEST_CHECK(!parsed.resp);
		TEST_CHECK(!parsed.offer);
		TEST_CHECK(parsed.answer);

		if(parsed.answer)
		{
			TEST_EQUAL(std::string(parsed.answer->offer_id.data(), parsed.answer->offer_id.size()), "yyyyyyyyyyyyyyyy");
			TEST_EQUAL(parsed.answer->sdp, "SDP\r\n");
		}
	}
}

TORRENT_TEST(parse_websocket_tracker_invalid_json)
{
	char const response[] = R"({"invalid":foo)";

	error_code ec;
	auto ret = aux::parse_websocket_tracker_response({response, long(std::strlen(response))}, ec);

	TEST_EQUAL(ec, error_code(errors::invalid_tracker_response));
	TEST_CHECK(std::holds_alternative<std::string>(ret));
	std::cout << "message: " << std::get<std::string>(ret) << std::endl;
}

TORRENT_TEST(parse_websocket_tracker_invalid_response)
{
	std::array<char const*, 12> responses =
	{
		// not an object
		R"([ "foo" ])",

		// info_hash too short
		R"({"complete":1,"incomplete":0,"action":"announce","interval":120,"info_hash":"tooshort"})",

		// missing info_hash
		R"({"complete":1,"incomplete":0,"action":"announce","interval":120})",

		// info_hash too long
		R"({"complete":1,"incomplete":0,"action":"announce","interval":120,"info_hash":"aaaaaaaaaaaaaaaaaaaaa"})",

		// offer with peer_id too short
		R"({"action":"announce","offer":{"type":"offer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"bbbbbbbbbbbbbbbbbbb","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// offer with peer_id too long
		R"({"action":"announce","offer":{"type":"offer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"aaaaaaaaaaaaaaaaaaaaa","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// answer with peer_id too short
		R"({"action":"announce","answer":{"type":"answer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"bbbbbbbbbbbbbbbbbbb","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// answer with peer_id too long
		R"({"action":"announce","answer":{"type":"answer","sdp":"SDP\r\n"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"aaaaaaaaaaaaaaaaaaaaa","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// offer without sdp
		R"({"action":"announce","offer":{"type":"offer"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// answer without sdp
		R"({"action":"announce","answer":{"type":"answer"},"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// offer not an object
		R"({"action":"announce","offer": "foo","offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})",

		// answer not an object
		R"({"action":"announce","answer": ["foo","bar"],"offer_id":"yyyyyyyyyyyyyyyy","peer_id":"-LT2000-p!SALH(DnYsi","info_hash":"xxxxxxxxxxxxxxxxxxxx"})"
	};

	for(const auto& response : responses)
	{
		error_code ec;
		auto ret = aux::parse_websocket_tracker_response({response, long(std::strlen(response))}, ec);

		std::cout << "tracker response: " << response << std::endl;
		std::cout << "error: " << ec.message() << std::endl;
		TEST_EQUAL(ec, error_code(errors::invalid_tracker_response));
		TEST_CHECK(std::holds_alternative<std::string>(ret));
		std::cout << "message: " << std::get<std::string>(ret) << std::endl;
	}
}

TORRENT_TEST(websocket_tracker)
{
	int const http_port = start_websocket_server();

	settings_pack pack = settings();
	pack.set_bool(settings_pack::announce_to_all_trackers, true);

	auto s = std::make_unique<lt::session>(pack);

	error_code ec;
	remove_all("tmp4_tracker", ec);
	create_directory("tmp4_tracker", ec);
	std::ofstream file(combine_path("tmp4_tracker", "temporary").c_str());
	add_torrent_params addp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	char tracker_url[200];
	std::snprintf(tracker_url, sizeof(tracker_url), "ws://127.0.0.1:%d/announce"
		, http_port);
	addp.trackers.push_back(tracker_url);

	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.flags |= torrent_flags::seed_mode;
	addp.save_path = "tmp4_tracker";
	torrent_handle h = s->add_torrent(addp);

	lt::torrent_status status = h.status();
	TEST_CHECK(status.current_tracker.empty());

	wait_for_alert(*s, tracker_reply_alert::alert_type, "s");

	std::this_thread::sleep_for(lt::milliseconds(2000));

	status = h.status();
	TEST_CHECK(!status.current_tracker.empty());
	TEST_EQUAL(status.current_tracker, tracker_url);

	std::printf("destructing session\n");
	s.reset();
	std::printf("done\n");

	std::printf("stop_websocket_server\n");
	stop_websocket_server();
	std::printf("done\n");
}
#endif

namespace {

void test_proxy(bool proxy_trackers)
{
	int http_port = start_web_server();

	settings_pack pack = settings();
	pack.set_bool(settings_pack::announce_to_all_trackers, true);
	pack.set_bool(settings_pack::announce_to_all_tiers, false);
	pack.set_int(settings_pack::tracker_completion_timeout, 2);
	pack.set_int(settings_pack::tracker_receive_timeout, 1);
	pack.set_str(settings_pack::listen_interfaces, test_listen_interface());

	pack.set_str(settings_pack::proxy_hostname, "non-existing.com");
	pack.set_int(settings_pack::proxy_type, settings_pack::socks5);
	pack.set_int(settings_pack::proxy_port, 4444);
	pack.set_bool(settings_pack::proxy_tracker_connections, proxy_trackers);

	auto s = std::make_unique<lt::session>(pack);

	error_code ec;
	remove_all("tmp2_tracker", ec);
	create_directory("tmp2_tracker", ec);
	ofstream file(combine_path("tmp2_tracker", "temporary").c_str());
	add_torrent_params addp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	char tracker_url[200];
	// and this should not be announced to (since the one before it succeeded)
	std::snprintf(tracker_url, sizeof(tracker_url), "http://127.0.0.1:%d/announce"
		, http_port);
	addp.trackers.push_back(tracker_url);

	addp.flags &= ~torrent_flags::paused;
	addp.flags &= ~torrent_flags::auto_managed;
	addp.flags |= torrent_flags::seed_mode;
	addp.save_path = "tmp2_tracker";
	torrent_handle h = s->add_torrent(addp);

	// wait to hit the tracker
	const alert* a = wait_for_alert(*s, tracker_reply_alert::alert_type, "s");
	if (proxy_trackers)
	{
		TEST_CHECK(a == nullptr);
	}
	else
	{
		TEST_CHECK(a != nullptr);
	}

	std::printf("destructing session\n");
	s.reset();
	std::printf("done\n");

	std::printf("stop_web_server\n");
	stop_web_server();
	std::printf("done\n");
}

} // anonymous namespace

TORRENT_TEST(tracker_proxy)
{
	std::printf("\n\nnot proxying tracker connections (expect to reach the tracker)\n\n");
	test_proxy(false);

	std::printf("\n\nproxying tracker connections through non-existent proxy "
		"(do not expect to reach the tracker)\n\n");
	test_proxy(true);
}

#ifndef TORRENT_DISABLE_LOGGING
#ifndef TORRENT_DISABLE_ALERT_MSG
namespace {
void test_stop_tracker_timeout(int const timeout)
{
	// trick the min interval so that the stopped announce is permitted immediately
	// after the initial announce
	int port = start_web_server(false, false, true, -1);

	auto count_stopped_events = [](session& ses, int expected)
	{
		int count = 0;
		int num = 70; // this number is adjusted per version, an estimate
		time_point const end_time = clock_type::now() + seconds(15);
		while (true)
		{
			time_point const now = clock_type::now();
			if (now > end_time) return count;

			ses.wait_for_alert(end_time - now);
			std::vector<alert*> alerts;
			ses.pop_alerts(&alerts);
			for (auto a : alerts)
			{
				std::printf("%d: [%s] %s\n", num, a->what(), a->message().c_str());
				if (a->type() == log_alert::alert_type)
				{
					std::string const msg = a->message();
					if (msg.find("&event=stopped") != std::string::npos)
					{
						count++;
						--expected;
					}
				}
				num--;
			}
			if (num <= 0 && expected <= 0) return count;
		}
	};

	settings_pack p = settings();
	p.set_bool(settings_pack::announce_to_all_trackers, true);
	p.set_bool(settings_pack::announce_to_all_tiers, true);
	p.set_str(settings_pack::listen_interfaces, "127.0.0.1:6881");
	p.set_int(settings_pack::stop_tracker_timeout, timeout);

	lt::session s(p);

	error_code ec;
	remove_all("tmp4_tracker", ec);
	create_directory("tmp4_tracker", ec);
	ofstream file(combine_path("tmp4_tracker", "temporary").c_str());
	add_torrent_params tp = ::create_torrent(&file, "temporary", 16 * 1024, 13, false);
	file.close();

	tp.flags &= ~torrent_flags::paused;
	tp.flags &= ~torrent_flags::auto_managed;
	tp.flags |= torrent_flags::seed_mode;
	tp.save_path = "tmp4_tracker";
	torrent_handle h = s.add_torrent(tp);

	char tracker_url[200];
	std::snprintf(tracker_url, sizeof(tracker_url), "http://127.0.0.1:%d/announce", port);
	announce_entry ae{tracker_url};
	h.add_tracker(ae);

	// make sure it announced a event=started properly
	// expect announces for v1 and v2 info hashes
	for (int i = 0; i < 2; ++i)
		wait_for_alert(s, tracker_reply_alert::alert_type, "s");

	s.remove_torrent(h);

	int const count = count_stopped_events(s, (timeout == 0) ? 0 : 2);
	TEST_EQUAL(count, (timeout == 0) ? 0 : 2);

	stop_web_server();
}
} // anonymous namespace

TORRENT_TEST(stop_tracker_timeout)
{
	std::printf("\n\nexpect to get ONE request with &event=stopped\n\n");
	test_stop_tracker_timeout(1);
}

TORRENT_TEST(stop_tracker_timeout_zero_timeout)
{
	std::printf("\n\nexpect to NOT get a request with &event=stopped\n\n");
	test_stop_tracker_timeout(0);
}
#endif
#endif