text: /*
  
  Copyright (c) 2014-2019, Arvid Norberg
  Copyright (c) 2016, 2018, Alden Torres
  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/peer_list.hpp"
  #include "libtorrent/torrent_handle.hpp"
  #include "libtorrent/torrent_peer_allocator.hpp"
  #include "libtorrent/peer_connection_interface.hpp"
  #include "libtorrent/stat.hpp"
  #include "libtorrent/ip_voter.hpp"
  #include "libtorrent/ip_filter.hpp"
  #include "libtorrent/peer_info.hpp"
  #include "libtorrent/random.hpp"
  #include "libtorrent/socket_io.hpp"
  
  #include "test.hpp"
  #include "setup_transfer.hpp"
  #include <vector>
  #include <memory> // for shared_ptr
  #include <cstdarg>
  
  using namespace lt;
  
  namespace {
  
  struct mock_torrent;
  
  struct mock_peer_connection
  	: peer_connection_interface
  	, std::enable_shared_from_this<mock_peer_connection>
  {
  	mock_peer_connection(mock_torrent* tor, bool out, tcp::endpoint const& remote)
  		: m_choked(false)
  		, m_outgoing(out)
  		, m_tp(nullptr)
  		, m_remote(remote)
  		, m_local(ep("127.0.0.1", 8080))
  		, m_our_id(nullptr)
  		, m_disconnect_called(false)
  		, m_torrent(*tor)
  	{
  		aux::random_bytes(m_id);
  	}
  
  	virtual ~mock_peer_connection() = default;
  
  #if !defined TORRENT_DISABLE_LOGGING
  	bool should_log(peer_log_alert::direction_t) const noexcept override
  	{ return true; }
  
  	void peer_log(peer_log_alert::direction_t, char const* /*event*/
  		, char const* fmt, ...) const noexcept override
  	{
  		va_list v;
  		va_start(v, fmt);
  #ifdef __clang__
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wformat-nonliteral"
  #endif
  		std::vprintf(fmt, v);
  #ifdef __clang__
  #pragma clang diagnostic pop
  #endif
  		va_end(v);
  	}
  #endif
  
  	bool was_disconnected() const { return m_disconnect_called; }
  	void set_local_ep(tcp::endpoint const& ep) { m_local = ep; }
  
  	lt::stat m_stat;
  	bool m_choked;
  	bool m_outgoing;
  	torrent_peer* m_tp;
  	tcp::endpoint m_remote;
  	tcp::endpoint m_local;
  	peer_id m_id;
  	peer_id m_our_id;
  	bool m_disconnect_called;
  	mock_torrent& m_torrent;
  
  	void get_peer_info(peer_info&) const override {}
  	tcp::endpoint const& remote() const override { return m_remote; }
  	tcp::endpoint local_endpoint() const override { return m_local; }
  	void disconnect(error_code const& ec
  		, operation_t op, disconnect_severity_t error = peer_connection_interface::normal) override;
  	peer_id const& pid() const override { return m_id; }
  	peer_id our_pid() const override { return m_our_id; }
  	void set_holepunch_mode() override {}
  	torrent_peer* peer_info_struct() const override { return m_tp; }
  	void set_peer_info(torrent_peer* pi) override { m_tp = pi; }
  	bool is_outgoing() const override { return m_outgoing; }
  	void add_stat(std::int64_t downloaded, std::int64_t uploaded) override
  	{ m_stat.add_stat(downloaded, uploaded); }
  	bool fast_reconnect() const override { return true; }
  	bool is_choked() const override { return m_choked; }
  	bool failed() const override { return false; }
  	lt::stat const& statistics() const override { return m_stat; }
  };
  
  struct mock_torrent
  {
  	explicit mock_torrent(torrent_state* st) : m_p(nullptr), m_state(st) {}
  	virtual ~mock_torrent() = default;
  
  	bool connect_to_peer(torrent_peer* peerinfo)
  	{
  		TORRENT_ASSERT(peerinfo->connection == nullptr);
  		if (peerinfo->connection) return false;
  		auto c = std::make_shared<mock_peer_connection>(this, true, peerinfo->ip());
  		c->set_peer_info(peerinfo);
  
  		m_connections.push_back(c);
  		m_p->set_connection(peerinfo, c.get());
  		return true;
  	}
  
  	peer_list* m_p;
  	torrent_state* m_state;
  	std::vector<std::shared_ptr<mock_peer_connection>> m_connections;
  };
  
  void mock_peer_connection::disconnect(error_code const&
  	, operation_t, disconnect_severity_t)
  {
  	m_torrent.m_p->connection_closed(*this, 0, m_torrent.m_state);
  	auto const i = std::find(m_torrent.m_connections.begin(), m_torrent.m_connections.end()
  		, std::static_pointer_cast<mock_peer_connection>(shared_from_this()));
  	if (i != m_torrent.m_connections.end()) m_torrent.m_connections.erase(i);
  
  	m_tp = nullptr;
  	m_disconnect_called = true;
  }
  
  bool has_peer(peer_list const& p, tcp::endpoint const& ep)
  {
  	auto const its = p.find_peers(ep.address());
  	return its.first != its.second;
  }
  
  torrent_state init_state()
  {
  	torrent_state st;
  	st.is_finished = false;
  	st.max_peerlist_size = 1000;
  	st.allow_multiple_connections_per_ip = false;
  	st.port = 9999;
  	return st;
  }
  
  torrent_peer* add_peer(peer_list& p, torrent_state& st, tcp::endpoint const& ep)
  {
  	int cc = p.num_connect_candidates();
  	torrent_peer* peer = p.add_peer(ep, {}, {}, &st);
  	if (peer)
  	{
  		TEST_EQUAL(p.num_connect_candidates(), cc + 1);
  		TEST_EQUAL(peer->port, ep.port());
  	}
  	st.erased.clear();
  	return peer;
  }
  
  void connect_peer(peer_list& p, mock_torrent& t, torrent_state& st)
  {
  	torrent_peer* tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp);
  	if (!tp) return;
  	t.connect_to_peer(tp);
  	st.erased.clear();
  	TEST_CHECK(tp->connection);
  }
  
  static torrent_peer_allocator allocator;
  
  } // anonymous namespace
  
  // test multiple peers with the same IP
  // when disallowing it
  TORRENT_TEST(multiple_ips_disallowed)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	torrent_peer* peer1 = p.add_peer(ep("10.0.0.2", 3000), {}, {}, &st);
  
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	st.erased.clear();
  
  	torrent_peer* peer2 = p.add_peer(ep("10.0.0.2", 9020), {}, {}, &st);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(peer1, peer2);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	st.erased.clear();
  }
  
  // test multiple peers with the same IP
  // when allowing it
  TORRENT_TEST(multiple_ips_allowed)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = true;
  	peer_list p(allocator);
  	t.m_p = &p;
  	torrent_peer* peer1 = p.add_peer(ep("10.0.0.2", 3000), {}, {}, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	TEST_EQUAL(p.num_peers(), 1);
  	st.erased.clear();
  
  	torrent_peer* peer2 = p.add_peer(ep("10.0.0.2", 9020), {}, {}, &st);
  	TEST_EQUAL(p.num_peers(), 2);
  	TEST_CHECK(peer1 != peer2);
  	TEST_EQUAL(p.num_connect_candidates(), 2);
  	st.erased.clear();
  }
  
  // test adding two peers with the same IP, but different ports, to
  // make sure they can be connected at the same time
  // with allow_multiple_connections_per_ip enabled
  TORRENT_TEST(multiple_ips_allowed2)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = true;
  	peer_list p(allocator);
  	t.m_p = &p;
  	torrent_peer* peer1 = p.add_peer(ep("10.0.0.2", 3000), {}, {}, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	st.erased.clear();
  
  	TEST_EQUAL(p.num_peers(), 1);
  	torrent_peer* tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp);
  	t.connect_to_peer(tp);
  	st.erased.clear();
  
  	// we only have one peer, we can't
  	// connect another one
  	tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp == nullptr);
  	st.erased.clear();
  
  	torrent_peer* peer2 = p.add_peer(ep("10.0.0.2", 9020), {}, {}, &st);
  	TEST_EQUAL(p.num_peers(), 2);
  	TEST_CHECK(peer1 != peer2);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	st.erased.clear();
  
  	tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp);
  	t.connect_to_peer(tp);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	st.erased.clear();
  }
  
  // test adding two peers with the same IP, but different ports, to
  // make sure they can not be connected at the same time
  // with allow_multiple_connections_per_ip disabled
  TORRENT_TEST(multiple_ips_disallowed2)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  	torrent_peer* peer1 = p.add_peer(ep("10.0.0.2", 3000), {}, {}, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	TEST_EQUAL(peer1->port, 3000);
  	st.erased.clear();
  
  	TEST_EQUAL(p.num_peers(), 1);
  	torrent_peer* tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp);
  	t.connect_to_peer(tp);
  	st.erased.clear();
  
  	// we only have one peer, we can't
  	// connect another one
  	tp = p.connect_one_peer(0, &st);
  	TEST_CHECK(tp == nullptr);
  	st.erased.clear();
  
  	torrent_peer* peer2 = p.add_peer(ep("10.0.0.2", 9020), {}, {}, &st);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(peer2->port, 9020);
  		TEST_CHECK(peer1 == peer2);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	st.erased.clear();
  }
  
  // test incoming connection
  // and update_peer_port
  TORRENT_TEST(update_peer_port)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	auto c = std::make_shared<mock_peer_connection>(&t, true, ep("10.0.0.1", 8080));
  	p.new_connection(*c, 0, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	TEST_EQUAL(p.num_peers(), 1);
  	st.erased.clear();
  
  	p.update_peer_port(4000, c->peer_info_struct(), peer_info::incoming, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(c->peer_info_struct()->port, 4000);
  	st.erased.clear();
  }
  
  // test incoming connection
  // and update_peer_port, causing collission
  TORRENT_TEST(update_peer_port_collide)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = true;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer2 = p.add_peer(ep("10.0.0.1", 4000), {}, {}, &st);
  	TEST_CHECK(peer2);
  
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	auto c = std::make_shared<mock_peer_connection>(&t, true, ep("10.0.0.1", 8080));
  	p.new_connection(*c, 0, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	// at this point we have two peers, because we think they have different
  	// ports
  	TEST_EQUAL(p.num_peers(), 2);
  	st.erased.clear();
  
  		// this peer will end up having the same port as the existing peer in the list
  	p.update_peer_port(4000, c->peer_info_struct(), peer_info::incoming, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	// the expected behavior is to replace that one
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(c->peer_info_struct()->port, 4000);
  	st.erased.clear();
  }
  
  namespace {
  std::shared_ptr<mock_peer_connection> shared_from_this(lt::peer_connection_interface* p)
  {
  	return std::static_pointer_cast<mock_peer_connection>(
  		static_cast<mock_peer_connection*>(p)->shared_from_this());
  }
  } // anonymous namespace
  
  // test ip filter
  TORRENT_TEST(ip_filter)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// add peer 1
  	torrent_peer* peer1 = add_peer(p, st, ep("10.0.0.2", 3000));
  	torrent_peer* peer2 = add_peer(p, st, ep("11.0.0.2", 9020));
  
  	TEST_CHECK(peer1 != peer2);
  
  	connect_peer(p, t, st);
  	connect_peer(p, t, st);
  
  	auto con1 = shared_from_this(peer1->connection);
  	TEST_EQUAL(con1->was_disconnected(), false);
  	auto con2 = shared_from_this(peer2->connection);
  	TEST_EQUAL(con2->was_disconnected(), false);
  
  	// now, filter one of the IPs and make sure the peer is removed
  	ip_filter filter;
  	filter.add_rule(addr4("11.0.0.0"), addr4("255.255.255.255"), 1);
  	std::vector<address> banned;
  	p.apply_ip_filter(filter, &st, banned);
  	// we just erased a peer, because it was filtered by the ip filter
  	TEST_EQUAL(st.erased.size(), 1);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(banned.size(), 1);
  	TEST_EQUAL(banned[0], addr4("11.0.0.2"));
  	TEST_EQUAL(con2->was_disconnected(), true);
  	TEST_EQUAL(con1->was_disconnected(), false);
  }
  
  // test port filter
  TORRENT_TEST(port_filter)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// add peer 1
  	torrent_peer* peer1 = add_peer(p, st, ep("10.0.0.2", 3000));
  	torrent_peer* peer2 = add_peer(p, st, ep("11.0.0.2", 9020));
  
  	TEST_CHECK(peer1 != peer2);
  
  	connect_peer(p, t, st);
  	connect_peer(p, t, st);
  
  	auto con1 = shared_from_this(peer1->connection);
  	TEST_EQUAL(con1->was_disconnected(), false);
  	auto con2 = shared_from_this(peer2->connection);
  	TEST_EQUAL(con2->was_disconnected(), false);
  
  	// now, filter one of the IPs and make sure the peer is removed
  	port_filter filter;
  	filter.add_rule(9000, 10000, 1);
  	std::vector<address> banned;
  	p.apply_port_filter(filter, &st, banned);
  	// we just erased a peer, because it was filtered by the ip filter
  	TEST_EQUAL(st.erased.size(), 1);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(banned.size(), 1);
  	TEST_EQUAL(banned[0], addr4("11.0.0.2"));
  	TEST_EQUAL(con2->was_disconnected(), true);
  	TEST_EQUAL(con1->was_disconnected(), false);
  }
  
  // test banning peers
  TORRENT_TEST(ban_peers)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer1 = add_peer(p, st, ep("10.0.0.1", 4000));
  
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  	auto c = std::make_shared<mock_peer_connection>(&t, true, ep("10.0.0.1", 8080));
  	p.new_connection(*c, 0, &st);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	TEST_EQUAL(p.num_peers(), 1);
  	st.erased.clear();
  
  	// now, ban the peer
  	bool ok = p.ban_peer(c->peer_info_struct());
  	TEST_EQUAL(ok, true);
  	TEST_EQUAL(peer1->banned, true);
  	// we still have it in the list
  	TEST_EQUAL(p.num_peers(), 1);
  	// it's just not a connect candidate, nor allowed to receive incoming connections
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  
  	p.connection_closed(*c, 0, &st);
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	st.erased.clear();
  
  	c = std::make_shared<mock_peer_connection>(&t, true, ep("10.0.0.1", 8080));
  	ok = p.new_connection(*c, 0, &st);
  	// since it's banned, we should not allow this incoming connection
  	TEST_EQUAL(ok, false);
  	TEST_EQUAL(p.num_connect_candidates(), 0);
  	st.erased.clear();
  }
  
  // test erase_peers when we fill up the peer list
  TORRENT_TEST(erase_peers)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.max_peerlist_size = 100;
  	st.allow_multiple_connections_per_ip = true;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	for (int i = 0; i < 100; ++i)
  	{
  		TEST_EQUAL(st.erased.size(), 0);
  		tcp::endpoint ep = rand_tcp_ep();
  		torrent_peer* peer = add_peer(p, st, ep);
  		TEST_CHECK(peer);
  		if (peer == nullptr || st.erased.size() > 0)
  		{
  			std::printf("unexpected rejection of peer: %s | %d in list. "
  				"added peer %p, erased %d peers\n"
  				, print_endpoint(ep).c_str(), p.num_peers(), static_cast<void*>(peer)
  				, int(st.erased.size()));
  		}
  	}
  	TEST_EQUAL(p.num_peers(), 100);
  
  	// trigger the eviction of one peer
  	torrent_peer* peer = p.add_peer(rand_tcp_ep(), {}, {}, &st);
  	// we either removed an existing peer, or rejected this one
  	// either is valid behavior when the list is full
  	TEST_CHECK(st.erased.size() == 1 || peer == nullptr);
  }
  
  // test set_ip_filter
  TORRENT_TEST(set_ip_filter)
  {
  	torrent_state st = init_state();
  	std::vector<address> banned;
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	for (int i = 0; i < 100; ++i)
  	{
  		p.add_peer(tcp::endpoint(
  			address_v4(std::uint32_t((10 << 24) + ((i + 10) << 16))), 353), {}, {}, &st);
  		TEST_EQUAL(st.erased.size(), 0);
  		st.erased.clear();
  	}
  	TEST_EQUAL(p.num_peers(), 100);
  	TEST_EQUAL(p.num_connect_candidates(), 100);
  
  	// trigger the removal of one peer
  	ip_filter filter;
  	filter.add_rule(addr4("10.13.0.0"), addr4("10.13.255.255"), ip_filter::blocked);
  	p.apply_ip_filter(filter, &st, banned);
  	TEST_EQUAL(st.erased.size(), 1);
  	TEST_EQUAL(st.erased[0]->address(), addr4("10.13.0.0"));
  	TEST_EQUAL(p.num_peers(), 99);
  	TEST_EQUAL(p.num_connect_candidates(), 99);
  }
  
  // test set_port_filter
  TORRENT_TEST(set_port_filter)
  {
  	torrent_state st = init_state();
  	std::vector<address> banned;
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	for (int i = 0; i < 100; ++i)
  	{
  		p.add_peer(tcp::endpoint(
  			address_v4(std::uint32_t((10 << 24) + ((i + 10) << 16))), std::uint16_t(i + 10)), {}, {}, &st);
  		TEST_EQUAL(st.erased.size(), 0);
  		st.erased.clear();
  	}
  	TEST_EQUAL(p.num_peers(), 100);
  	TEST_EQUAL(p.num_connect_candidates(), 100);
  
  	// trigger the removal of one peer
  	port_filter filter;
  	filter.add_rule(13, 13, port_filter::blocked);
  	p.apply_port_filter(filter, &st, banned);
  	TEST_EQUAL(st.erased.size(), 1);
  	TEST_EQUAL(st.erased[0]->address(), addr4("10.13.0.0"));
  	TEST_EQUAL(st.erased[0]->port, 13);
  	TEST_EQUAL(p.num_peers(), 99);
  	TEST_EQUAL(p.num_connect_candidates(), 99);
  }
  
  // test set_max_failcount
  TORRENT_TEST(set_max_failcount)
  {
  	torrent_state st = init_state();
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	for (int i = 0; i < 100; ++i)
  	{
  		torrent_peer* peer = p.add_peer(tcp::endpoint(
  			address_v4(std::uint32_t((10 << 24) + ((i + 10) << 16))), std::uint16_t(i + 10)), {}, {}, &st);
  		TEST_EQUAL(st.erased.size(), 0);
  		st.erased.clear();
  		// every other peer has a failcount of 1
  		if (i % 2) p.inc_failcount(peer);
  	}
  	TEST_EQUAL(p.num_peers(), 100);
  	TEST_EQUAL(p.num_connect_candidates(), 100);
  
  	// set the max failcount to 1 and observe how half the peers no longer
  	// are connect candidates
  	st.max_failcount = 1;
  	p.set_max_failcount(&st);
  
  	TEST_EQUAL(p.num_connect_candidates(), 50);
  	TEST_EQUAL(p.num_peers(), 100);
  }
  
  // test set_seed
  TORRENT_TEST(set_seed)
  {
  	torrent_state st = init_state();
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	for (int i = 0; i < 100; ++i)
  	{
  		torrent_peer* peer = p.add_peer(tcp::endpoint(
  			address_v4(std::uint32_t((10 << 24) + ((i + 10) << 16))), std::uint16_t(i + 10)), {}, {}, &st);
  		TEST_EQUAL(st.erased.size(), 0);
  		st.erased.clear();
  		// make every other peer a seed
  		if (i % 2) p.set_seed(peer, true);
  	}
  	TEST_EQUAL(p.num_peers(), 100);
  	TEST_EQUAL(p.num_connect_candidates(), 100);
  
  	// now, the torrent completes and we're no longer interested in
  	// connecting to seeds. Make sure half the peers are no longer
  	// considered connect candidates
  	st.is_finished = true;
  
  	// this will make the peer_list recalculate the connect candidates
  	std::vector<torrent_peer*> peers;
  	p.connect_one_peer(1, &st);
  
  	TEST_EQUAL(p.num_connect_candidates(), 50);
  	TEST_EQUAL(p.num_peers(), 100);
  }
  
  // test has_peer
  TORRENT_TEST(has_peer)
  {
  	torrent_state st = init_state();
  	std::vector<address> banned;
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer1 = add_peer(p, st, ep("10.10.0.1", 10));
  	torrent_peer* peer2 = add_peer(p, st, ep("10.10.0.2", 11));
  
  	TEST_EQUAL(p.num_peers(), 2);
  	TEST_EQUAL(p.num_connect_candidates(), 2);
  
  	TEST_EQUAL(p.has_peer(peer1), true);
  	TEST_EQUAL(p.has_peer(peer2), true);
  
  	ip_filter filter;
  	filter.add_rule(addr4("10.10.0.1"), addr4("10.10.0.1"), ip_filter::blocked);
  	p.apply_ip_filter(filter, &st, banned);
  	TEST_EQUAL(st.erased.size(), 1);
  	st.erased.clear();
  
  	TEST_EQUAL(p.num_peers(), 1);
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  
  	TEST_EQUAL(p.has_peer(peer1), false);
  	TEST_EQUAL(p.has_peer(peer2), true);
  }
  
  // test connect_candidates torrent_finish
  TORRENT_TEST(connect_candidates_finish)
  {
  	torrent_state st = init_state();
  	std::vector<address> banned;
  
  	mock_torrent t(&st);
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer1 = add_peer(p, st, ep("10.10.0.1", 10));
  	TEST_CHECK(peer1);
  	p.set_seed(peer1, true);
  	torrent_peer* peer2 = add_peer(p, st, ep("10.10.0.2", 11));
  	TEST_CHECK(peer2);
  	p.set_seed(peer2, true);
  	torrent_peer* peer3 = add_peer(p, st, ep("10.10.0.3", 11));
  	TEST_CHECK(peer3);
  	p.set_seed(peer3, true);
  	torrent_peer* peer4 = add_peer(p, st, ep("10.10.0.4", 11));
  	TEST_CHECK(peer4);
  	torrent_peer* peer5 = add_peer(p, st, ep("10.10.0.5", 11));
  	TEST_CHECK(peer5);
  
  	TEST_EQUAL(p.num_peers(), 5);
  	TEST_EQUAL(p.num_connect_candidates(), 5);
  
  	st.is_finished = true;
  	// we're finished downloading now, only the non-seeds are
  	// connect candidates
  
  	// connect to one of them
  	connect_peer(p, t, st);
  
  	TEST_EQUAL(p.num_peers(), 5);
  	// and there should be one left
  	TEST_EQUAL(p.num_connect_candidates(), 1);
  }
  
  // test self-connection
  TORRENT_TEST(self_connection)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// add and connect peer
  	torrent_peer* peer = add_peer(p, st, ep("10.0.0.2", 3000));
  	connect_peer(p, t, st);
  
  	auto con_out = shared_from_this(peer->connection);
  	con_out->set_local_ep(ep("10.0.0.2", 8080));
  
  	auto con_in = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 8080));
  	con_in->set_local_ep(ep("10.0.0.2", 3000));
  
  	p.new_connection(*con_in, 0, &st);
  
  	// from the peer_list's point of view, this looks like we made one
  	// outgoing connection and received an incoming one. Since they share
  	// the exact same endpoints (IP ports) but just swapped source and
  	// destination, the peer list is supposed to figure out that we connected
  	// to ourself and disconnect it
  	TEST_EQUAL(con_out->was_disconnected(), true);
  	TEST_EQUAL(con_in->was_disconnected(), true);
  }
  
  // test double connection (both incoming)
  TORRENT_TEST(double_connection)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// we are 10.0.0.1 and the other peer is 10.0.0.2
  
  	// first incoming connection
  	auto con1 = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 7528));
  	con1->set_local_ep(ep("10.0.0.1", 8080));
  
  	p.new_connection(*con1, 0, &st);
  
  	// and the incoming connection
  	auto con2 = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 3561));
  	con2->set_local_ep(ep("10.0.0.1", 8080));
  
  	p.new_connection(*con2, 0, &st);
  
  	// the second incoming connection should be closed
  	TEST_EQUAL(con1->was_disconnected(), false);
  	TEST_EQUAL(con2->was_disconnected(), true);
  }
  
  // test double connection (we loose)
  TORRENT_TEST(double_connection_loose)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// we are 10.0.0.1 and the other peer is 10.0.0.2
  
  	// our outgoing connection
  	torrent_peer* peer = add_peer(p, st, ep("10.0.0.2", 3000));
  	connect_peer(p, t, st);
  
  	auto con_out = shared_from_this(peer->connection);
  	con_out->set_local_ep(ep("10.0.0.1", 3163));
  
  	// and the incoming connection
  	auto con_in = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 3561));
  	con_in->set_local_ep(ep("10.0.0.1", 8080));
  
  	p.new_connection(*con_in, 0, &st);
  
  	// the rules are documented in peer_list.cpp
  	TEST_EQUAL(con_out->was_disconnected(), true);
  	TEST_EQUAL(con_in->was_disconnected(), false);
  }
  
  // test double connection with identical ports (random)
  TORRENT_TEST(double_connection_random)
  {
  	int in = 0;
  	int out = 0;
  	for (int i = 0; i < 30; ++i)
  	{
  		torrent_state st = init_state();
  		mock_torrent t(&st);
  		st.allow_multiple_connections_per_ip = false;
  		peer_list p(allocator);
  		t.m_p = &p;
  
  		// we are 10.0.0.1 and the other peer is 10.0.0.2
  
  		// our outgoing connection
  		torrent_peer* peer = add_peer(p, st, ep("10.0.0.2", 3000));
  		connect_peer(p, t, st);
  
  		auto con_out = static_cast<mock_peer_connection*>(peer->connection)->shared_from_this();
  		con_out->set_local_ep(ep("10.0.0.1", 3000));
  
  		// and the incoming connection
  		auto con_in = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 3000));
  		con_in->set_local_ep(ep("10.0.0.1", 3000));
  
  		p.new_connection(*con_in, 0, &st);
  
  		// the rules are documented in peer_list.cpp
  		out += con_out->was_disconnected();
  		in += con_in->was_disconnected();
  	}
  	// we should have gone different ways randomly
  	TEST_CHECK(out > 0);
  	TEST_CHECK(in > 0);
  }
  
  // test double connection (we win)
  TORRENT_TEST(double_connection_win)
  {
  	torrent_state st = init_state();
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	// we are 10.0.0.1 and the other peer is 10.0.0.2
  
  	// our outgoing connection
  	torrent_peer* peer = add_peer(p, st, ep("10.0.0.2", 8080));
  	connect_peer(p, t, st);
  
  	auto con_out = shared_from_this(peer->connection);
  	con_out->set_local_ep(ep("10.0.0.1", 3163));
  
  	//and the incoming connection
  	auto con_in = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.0.2", 3561));
  	con_in->set_local_ep(ep("10.0.0.1", 3000));
  
  	p.new_connection(*con_in, 0, &st);
  
  	// the rules are documented in peer_list.cpp
  	TEST_EQUAL(con_out->was_disconnected(), false);
  	TEST_EQUAL(con_in->was_disconnected(), true);
  }
  
  // test incoming connection when we are at the list size limit
  TORRENT_TEST(incoming_size_limit)
  {
  	torrent_state st = init_state();
  	st.max_peerlist_size = 5;
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer1 = add_peer(p, st, ep("10.0.0.1", 8080));
  	TEST_CHECK(peer1);
  	TEST_EQUAL(p.num_peers(), 1);
  	torrent_peer* peer2 = add_peer(p, st, ep("10.0.0.2", 8080));
  	TEST_CHECK(peer2);
  	TEST_EQUAL(p.num_peers(), 2);
  	torrent_peer* peer3 = add_peer(p, st, ep("10.0.0.3", 8080));
  	TEST_CHECK(peer3);
  	TEST_EQUAL(p.num_peers(), 3);
  	torrent_peer* peer4 = add_peer(p, st, ep("10.0.0.4", 8080));
  	TEST_CHECK(peer4);
  	TEST_EQUAL(p.num_peers(), 4);
  	torrent_peer* peer5 = add_peer(p, st, ep("10.0.0.5", 8080));
  	TEST_CHECK(peer5);
  	TEST_EQUAL(p.num_peers(), 5);
  
  	auto con_in = std::make_shared<mock_peer_connection>(&t, false, ep("10.0.1.2", 3561));
  	con_in->set_local_ep(ep("10.0.2.1", 3000));
  
  	// since we're already at 5 peers in the peer list, this call should
  	// erase one of the existing ones.
  	p.new_connection(*con_in, 0, &st);
  
  	TEST_EQUAL(con_in->was_disconnected(), false);
  	TEST_EQUAL(p.num_peers(), 5);
  
  	// one of the previous ones should have been removed
  	TEST_EQUAL(has_peer(p, ep("10.0.0.1", 8080))
  		+ has_peer(p, ep("10.0.0.2", 8080))
  		+ has_peer(p, ep("10.0.0.3", 8080))
  		+ has_peer(p, ep("10.0.0.4", 8080))
  		+ has_peer(p, ep("10.0.0.5", 8080))
  		, 4);
  }
  
  // test new peer when we are at the list size limit
  TORRENT_TEST(new_peer_size_limit)
  {
  	torrent_state st = init_state();
  	st.max_peerlist_size = 5;
  	mock_torrent t(&st);
  	st.allow_multiple_connections_per_ip = false;
  	peer_list p(allocator);
  	t.m_p = &p;
  
  	torrent_peer* peer1 = add_peer(p, st, ep("10.0.0.1", 8080));
  	TEST_CHECK(peer1);
  	TEST_EQUAL(p.num_peers(), 1);
  	torrent_peer* peer2 = add_peer(p, st, ep("10.0.0.2", 8080));
  	TEST_CHECK(peer2);
  	TEST_EQUAL(p.num_peers(), 2);
  	torrent_peer* peer3 = add_peer(p, st, ep("10.0.0.3", 8080));
  	TEST_CHECK(peer3);
  	TEST_EQUAL(p.num_peers(), 3);
  	torrent_peer* peer4 = add_peer(p, st, ep("10.0.0.4", 8080));
  	TEST_CHECK(peer4);
  	TEST_EQUAL(p.num_peers(), 4);
  	torrent_peer* peer5 = add_peer(p, st, ep("10.0.0.5", 8080));
  	TEST_CHECK(peer5);
  	TEST_EQUAL(p.num_peers(), 5);
  	torrent_peer* peer6 = p.add_peer(ep("10.0.0.6", 8080), {}, {}, &st);
  	TEST_CHECK(peer6 == nullptr);
  	TEST_EQUAL(p.num_peers(), 5);
  
  	// one of the connection should have been removed
  	TEST_EQUAL(has_peer(p, ep("10.0.0.1", 8080))
  		+ has_peer(p, ep("10.0.0.2", 8080))
  		+ has_peer(p, ep("10.0.0.3", 8080))
  		+ has_peer(p, ep("10.0.0.4", 8080))
  		+ has_peer(p, ep("10.0.0.5", 8080))
  		+ has_peer(p, ep("10.0.0.6", 8080))
  		, 5);
  }
  
  // TODO: test erasing peers
  // TODO: test update_peer_port with allow_multiple_connections_per_ip and without
  // TODO: test add i2p peers
  // TODO: test allow_i2p_mixed
  // TODO: test insert_peer failing with all error conditions
  // TODO: test IPv6
  // TODO: test connect_to_peer() failing
  // TODO: test connection_closed
  // TODO: connect candidates recalculation when incrementing failcount
  