/*

Copyright (c) 2007-2010, 2012, 2015-2020, 2022, Arvid Norberg

Copyright (c) 2016-2017, 2019, Alden Torres

Copyright (c) 2017, Pavel Pimenov

Copyright (c) 2018, Steven Siloti

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/asio/ip/host_name.hpp>

#include "libtorrent/aux_/disable_warnings_pop.hpp"

#include <cstdio> // for snprintf

#include <cinttypes> // for PRId64 et.al.

#include <cstdarg>

#include <functional>

#include <cstring> // for memcpy

#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_context.hpp"

#include "libtorrent/aux_/time.hpp"

#include "libtorrent/debug.hpp"

#include "libtorrent/random.hpp"

#include "libtorrent/aux_/ip_helpers.hpp" // for is_local

#include "libtorrent/aux_/escape_string.hpp"

#include "libtorrent/aux_/numeric_cast.hpp"

namespace libtorrent {

struct pcp_error_category final : boost::system::error_category

{

  const char* name() const BOOST_SYSTEM_NOEXCEPT override

  { return "pcp error"; }

  std::string message(int ev) const override

  {

    static char const* msgs[] =

    {

      "success",

      "unsupported version",

      "not authorized",

      "malformed request",

      "unsupported opcode",

      "unsupported option",

      "malformed option",

      "network failure",

      "no resources",

      "unsupported protocol",

      "user exceeded quota",

      "cannot provide external",

      "address mismatch",

      "excessive remote peers",

    };

    if (ev < 0 || ev >= int(sizeof(msgs)/sizeof(msgs[0])))

      return "Unknown error";

    return msgs[ev];

  }

  boost::system::error_condition default_error_condition(

    int ev) const BOOST_SYSTEM_NOEXCEPT override

  { return {ev, *this}; }

};

boost::system::error_category& pcp_category()

{

  static pcp_error_category pcp_category;

  return pcp_category;

}

namespace errors

{

  // hidden

  boost::system::error_code make_error_code(pcp_errors e)

  {

    return {e, pcp_category()};

  }

}

error_code natpmp::from_result_code(int const version, int result)

{

  if (version == version_natpmp)

  {

    // a few nat-pmp result codes map to different codes

    // in pcp

    switch (result)

    {

    case 3:result = 7; break;

    case 4:result = 8; break;

    case 5:result = 4; break;

    }

  }

  return errors::pcp_errors(result);

}

char const* natpmp::version_to_string(protocol_version version)

{

  return version == version_natpmp ? "NAT-PMP" : "PCP";

}

using namespace aux;

using namespace std::placeholders;

natpmp::natpmp(io_context& ios

  , aux::portmap_callback& cb

  , listen_socket_handle ls)

  : m_callback(cb)

  , m_socket(ios)

  , m_send_timer(ios)

  , m_refresh_timer(ios)

  , m_ioc(ios)

  , m_listen_handle(std::move(ls))

{

  // 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(ip_interface const& ip)

{

  TORRENT_ASSERT(is_single_thread());

  // assume servers support PCP and fall back to NAT-PMP

  // if necessary

  m_version = version_pcp;

  address const& local_address = ip.interface_address;

  error_code ec;

  auto const routes = enum_routes(m_ioc, ec);

  if (ec)

  {

#ifndef TORRENT_DISABLE_LOGGING

    if (should_log())

    {

      log("failed to enumerate routes: %s"

        , convert_from_native(ec.message()).c_str());

    }

#endif

    disable(ec);

  }

  auto const route = get_gateway(ip, routes);

  if (!route)

  {

#ifndef TORRENT_DISABLE_LOGGING

    if (should_log())

    {

      log("failed to find default route for \"%s\" %s"

        , ip.name, local_address.to_string().c_str());

    }

#endif

    disable(ec);

    return;

  }

  m_disabled = false;

  udp::endpoint const nat_endpoint(*route, 5351);

  if (nat_endpoint == m_nat_endpoint) return;

  m_nat_endpoint = nat_endpoint;

#ifndef TORRENT_DISABLE_LOGGING

  if (should_log())

  {

    log("found gateway at: %s"

      , print_address(m_nat_endpoint.address()).c_str());

  }

#endif

  m_socket.open(local_address.is_v4() ? udp::v4() : udp::v6(), ec);

  if (ec)

  {

    disable(ec);

    return;

  }

  m_socket.bind({local_address, 0}, ec);

  if (ec)

  {

    disable(ec);

    return;

  }

  ADD_OUTSTANDING_ASYNC("natpmp::on_reply");

  m_socket.async_receive_from(boost::asio::buffer(&m_response_buffer[0]

    , sizeof(m_response_buffer))

    , m_remote, std::bind(&natpmp::on_reply, self(), _1, _2));

  if (m_version == version_natpmp)

    send_get_ip_address_request();

  for (auto i = m_mappings.begin(), end(m_mappings.end()); i != end; ++i)

  {

    if (i->protocol == portmap_protocol::none

      || i->act != portmap_action::none)

      continue;

    i->act = portmap_action::add;

    update_mapping(port_mapping_t(int(i - m_mappings.begin())));

  }

}

void natpmp::send_get_ip_address_request()

{

  TORRENT_ASSERT(is_single_thread());

  using namespace libtorrent::aux;

  // this opcode only exists in NAT-PMP

  // PCP routers report the external IP in the response to a MAP operation

  TORRENT_ASSERT(m_version == version_natpmp);

  if (m_version != version_natpmp)

    return;

  char buf[2];

  char* out = buf;

  write_uint8(version_natpmp, out);

  write_uint8(0, out); // public IP address request opcode

#ifndef TORRENT_DISABLE_LOGGING

  log("==> get public IP address");

#endif

  error_code ec;

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

}

bool natpmp::get_mapping(port_mapping_t const index, int& local_port

  , int& external_port, portmap_protocol& protocol) const

{

  TORRENT_ASSERT(is_single_thread());

  TORRENT_ASSERT(index < m_mappings.end_index() && index >= port_mapping_t{});

  if (index >= m_mappings.end_index() || index < port_mapping_t{}) return false;

  mapping_t const& m = m_mappings[index];

  if (m.protocol == portmap_protocol::none) return false;

  local_port = m.local_port;

  external_port = m.external_port;

  protocol = m.protocol;

  return true;

}

#ifndef TORRENT_DISABLE_LOGGING

bool natpmp::should_log() const

{

  return m_callback.should_log_portmap(portmap_transport::natpmp);

}

void natpmp::mapping_log(char const* op, mapping_t const& m) const

{

  if (should_log())

  {

    log("%s-mapping: proto: %s port: %d local-port: %d action: %s ttl: %" PRId64

      , op

      , m.protocol == portmap_protocol::none

      ? "none" : to_string(m.protocol)

      , m.external_port

      , m.local_port

      , to_string(m.act)

      , (m.expires.time_since_epoch() != seconds(0))

        ? total_seconds(m.expires - aux::time_now())

        : std::int64_t(0));

  }

}

TORRENT_FORMAT(2, 3)

void natpmp::log(char const* fmt, ...) const

{

  TORRENT_ASSERT(is_single_thread());

  if (!should_log()) return;

  char msg[200];

  va_list v;

  va_start(v, fmt);

  std::vsnprintf(msg, sizeof(msg), fmt, v);

  va_end(v);

  m_callback.log_portmap(portmap_transport::natpmp, msg, m_listen_handle);

}

#endif

void natpmp::disable(error_code const& ec)

{

  TORRENT_ASSERT(is_single_thread());

  m_disabled = true;

  for (auto i = m_mappings.begin(), end(m_mappings.end()); i != end; ++i)

  {

    if (i->protocol == portmap_protocol::none) continue;

    portmap_protocol const proto = i->protocol;

    i->protocol = portmap_protocol::none;

    port_mapping_t const index(static_cast<int>(i - m_mappings.begin()));

    m_callback.on_port_mapping(index, address(), 0, proto, ec

      , portmap_transport::natpmp, m_listen_handle);

  }

  close_impl();

}

void natpmp::delete_mapping(port_mapping_t const index)

{

  TORRENT_ASSERT(is_single_thread());

  TORRENT_ASSERT(index < m_mappings.end_index() && index >= port_mapping_t{});

  if (index >= m_mappings.end_index() || index < port_mapping_t{}) return;

  mapping_t& m = m_mappings[index];

  if (m.protocol == portmap_protocol::none) return;

  if (!m.map_sent)

  {

    m.act = portmap_action::none;

    m.protocol = portmap_protocol::none;

    return;

  }

  m.act = portmap_action::del;

  update_mapping(index);

}

port_mapping_t natpmp::add_mapping(portmap_protocol const p, int const external_port

  , tcp::endpoint const local_ep, std::string const&)

{

  TORRENT_ASSERT(is_single_thread());

  if (m_disabled) return port_mapping_t{-1};

  auto i = std::find_if(m_mappings.begin()

    , m_mappings.end(), [] (mapping_t const& m) { return m.protocol == portmap_protocol::none; });

  if (i == m_mappings.end())

  {

    m_mappings.push_back(mapping_t());

    i = m_mappings.end() - 1;

  }

  aux::crypto_random_bytes(i->nonce);

  i->protocol = p;

  i->external_port = external_port;

  i->local_port = local_ep.port();

  i->act = portmap_action::add;

  port_mapping_t const mapping_index(static_cast<int>(i - m_mappings.begin()));

#ifndef TORRENT_DISABLE_LOGGING

  mapping_log("add",*i);

#endif

  update_mapping(mapping_index);

  return port_mapping_t{mapping_index};

}

void natpmp::try_next_mapping(port_mapping_t const i)

{

  TORRENT_ASSERT(is_single_thread());

  if (i < prev(m_mappings.end_index()))

  {

    update_mapping(next(i));

    return;

  }

  auto const m = std::find_if(

    m_mappings.begin(), m_mappings.end()

    , [] (mapping_t const& ma) { return ma.act != portmap_action::none

      && ma.protocol != portmap_protocol::none; });

  if (m == m_mappings.end())

  {

    if (m_abort)

    {

      m_send_timer.cancel();

      error_code ec;

      m_socket.close(ec);

    }

    return;

  }

  update_mapping(port_mapping_t(static_cast<int>(m - m_mappings.begin())));

}

void natpmp::update_mapping(port_mapping_t const i)

{

  TORRENT_ASSERT(is_single_thread());

  if (i == m_mappings.end_index())

  {

    if (m_abort)

    {

      m_send_timer.cancel();

      error_code ec;

      m_socket.close(ec);

    }

    return;

  }

  mapping_t const& m = m_mappings[i];

#ifndef TORRENT_DISABLE_LOGGING

  mapping_log("update", m);

#endif

  if (m.act == portmap_action::none

    || m.protocol == portmap_protocol::none)

  {

    try_next_mapping(i);

    return;

  }

  if (m_currently_mapping == port_mapping_t{-1})

  {

    // the socket is not currently in use

    // send out a mapping request

    m_retry_count = 0;

    send_map_request(i);

  }

}

void natpmp::send_map_request(port_mapping_t const i)

{

  TORRENT_ASSERT(is_single_thread());

  using namespace libtorrent::aux;

  TORRENT_ASSERT(m_currently_mapping == port_mapping_t{-1}

    || m_currently_mapping == i);

  m_currently_mapping = i;

  mapping_t& m = m_mappings[i];

  TORRENT_ASSERT(m.act != portmap_action::none);

  char buf[60];

  char* out = buf;

  int ttl = m.act == portmap_action::add ? 3600 : 0;

  if (m_version == version_natpmp)

  {

    write_uint8(m_version, out);

    write_uint8(m.protocol == portmap_protocol::udp ? 1 : 2, 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

    write_uint32(ttl, out); // port mapping lifetime

  }

  else if (m_version == version_pcp)

  {

    // PCP requires the use of IPv6 addresses even for IPv4 messages

    write_uint8(m_version, out);

    write_uint8(opcode_map, out);

    write_uint16(0, out); // reserved

    write_uint32(ttl, out);

    error_code ec;

    address const local_addr = m_socket.local_endpoint(ec).address();

    if (ec)

    {

#ifndef TORRENT_DISABLE_LOGGING

      if ( should_log())

      {

        log("*** port map, local_endpoint [ ec: %s:%d %s ]"

          , ec.category().name()

          , ec.value()

          , ec.message().c_str());

      }

#endif

      m_currently_mapping = port_mapping_t{-1};

      m.act = portmap_action::none;

      return;

    }

    auto const local_bytes = local_addr.is_v4()

      ? make_address_v6(v4_mapped, local_addr.to_v4()).to_bytes()

      : local_addr.to_v6().to_bytes();

    out = std::copy(local_bytes.begin(), local_bytes.end(), out);

    out = std::copy(m.nonce.begin(), m.nonce.end(), out);

    // translate portmap_protocol to an IANA protocol number

    int const protocol =

      (m.protocol == portmap_protocol::tcp) ? 6

      : (m.protocol == portmap_protocol::udp) ? 17

      : 0;

    write_int8(protocol, out);

    write_uint8(0, out); // reserved

    write_uint16(0, out); // reserved

    write_uint16(m.local_port, out);

    write_uint16(m.external_port, out);

    address_v6 external_addr;

    if (!m.external_address.is_unspecified())

    {

      external_addr = m.external_address.is_v4()

        ? make_address_v6(v4_mapped, m.external_address.to_v4())

        : m.external_address.to_v6();

    }

    else if (aux::is_local(local_addr))

    {

      external_addr = local_addr.is_v4()

        ? make_address_v6(v4_mapped, address_v4())

        : address_v6();

    }

    else if (local_addr.is_v4())

    {

      external_addr = make_address_v6(v4_mapped, local_addr.to_v4());

    }

    else

    {

      external_addr = local_addr.to_v6();

    }

    write_address(external_addr, out);

  }

  else

  {

    TORRENT_ASSERT_FAIL();

  }

#ifndef TORRENT_DISABLE_LOGGING

  if (should_log())

  {

    log("==> port map [ mapping: %d action: %s"

      " transport: %s proto: %s local: %d external: %d ttl: %d ]"

      , static_cast<int>(i), to_string(m.act)

      , version_to_string(m_version)

      , to_string(m.protocol)

      , m.local_port, m.external_port, ttl);

  }

#endif

  error_code ec;

  m_socket.send_to(boost::asio::buffer(buf, std::size_t(out - buf)), m_nat_endpoint, 0, ec);

#ifndef TORRENT_DISABLE_LOGGING

  if (ec && should_log())

  {

    log("*** port map [ ec: %s:%d %s ]"

      , ec.category().name()

      , ec.value()

      , ec.message().c_str());

  }

#endif

  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 = port_mapping_t{-1};

    m.act = portmap_action::none;

    try_next_mapping(i);

  }

  else

  {

    ADD_OUTSTANDING_ASYNC("natpmp::resend_request");

    // linear back-off instead of exponential

    ++m_retry_count;

    m_send_timer.expires_after(milliseconds(250 * m_retry_count));

    m_send_timer.async_wait(std::bind(&natpmp::on_resend_request, self(), i, _1));

  }

}

void natpmp::on_resend_request(port_mapping_t const i, error_code const& e)

{

  TORRENT_ASSERT(is_single_thread());

  COMPLETE_ASYNC("natpmp::resend_request");

  if (e) return;

  resend_request(i);

}

void natpmp::resend_request(port_mapping_t const i)

{

  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 = port_mapping_t{-1};

    m_mappings[i].act = portmap_action::none;

    // try again in two hours

    m_mappings[i].expires = aux::time_now() + hours(2);

    try_next_mapping(i);

    return;

  }

  send_map_request(i);

}

void natpmp::on_reply(error_code const& e

  , std::size_t const bytes_transferred)

{

  TORRENT_ASSERT(is_single_thread());

  COMPLETE_ASYNC("natpmp::on_reply");

  using namespace libtorrent::aux;

  if (e)

  {

#ifndef TORRENT_DISABLE_LOGGING

    if (should_log())

    {

      log("error on receiving reply: %s"

        , convert_from_native(e.message()).c_str());

    }

#endif

    return;

  }

  if (m_abort) return;

  ADD_OUTSTANDING_ASYNC("natpmp::on_reply");

  // make a copy of the response packet buffer

  // to avoid overwriting it in the next receive call

  std::array<char, sizeof(m_response_buffer)> msg_buf;

  std::memcpy(msg_buf.data(), m_response_buffer, bytes_transferred);

  m_socket.async_receive_from(boost::asio::buffer(&m_response_buffer[0]

    , sizeof(m_response_buffer))

    , m_remote, std::bind(&natpmp::on_reply, self(), _1, _2));

  if (m_remote != m_nat_endpoint)

  {

#ifndef TORRENT_DISABLE_LOGGING

    if (should_log())

    {

      log("received packet from wrong IP: %s"

        , print_endpoint(m_remote).c_str());

    }

#endif

    return;

  }

  m_send_timer.cancel();

  if (bytes_transferred < 4)

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("received packet of invalid size: %d", int(bytes_transferred));

#endif

    return;

  }

  char* in = msg_buf.data();

  int const version = read_uint8(in);

  if (version != version_natpmp && version != version_pcp)

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("unexpected version: %d", version);

#endif

    return;

  }

  int cmd = read_uint8(in);

  if (version == version_pcp)

  {

    cmd &= 0x7f;

  }

  int result;

  if (version == version_pcp)

  {

    ++in; // reserved

    result = read_uint8(in);

  }

  else

  {

    result = read_uint16(in);

  }

  if (result == errors::pcp_unsupp_version)

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("unsupported version");

#endif

    // ignore errors from local_endpoint

    error_code ec;

    if (m_version == version_pcp && !aux::is_v6(m_socket.local_endpoint(ec)))

    {

      m_version = version_natpmp;

      resend_request(m_currently_mapping);

      send_get_ip_address_request();

    }

    return;

  }

  if ((version == version_natpmp && bytes_transferred < 12)

    || (version == version_pcp && bytes_transferred < 24))

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("received packet of invalid size: %d", int(bytes_transferred));

#endif

    return;

  }

  int lifetime = 0;

  if (version == version_pcp)

  {

    lifetime = aux::numeric_cast<int>(read_uint32(in));

  }

  int const time = aux::numeric_cast<int>(read_uint32(in));

  if (version == version_pcp) in += 12; // reserved

  TORRENT_UNUSED(time);

  if (version == version_natpmp && cmd == 128)

  {

    // public IP request response

    m_external_ip = read_v4_address(in);

#ifndef TORRENT_DISABLE_LOGGING

    if (should_log())

    {

      log("<== public IP address [ %s ]", print_address(m_external_ip).c_str());

    }

#endif

    return;

  }

  if ((version == version_natpmp && bytes_transferred != 16)

    || (version == version_pcp && bytes_transferred != 60))

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("received packet of invalid size: %d", int(bytes_transferred));

#endif

    return;

  }

  std::array<char, 12> nonce;

  portmap_protocol protocol = portmap_protocol::none;

  if (version == version_pcp)

  {

    std::memcpy(nonce.data(), in, nonce.size());

    in += nonce.size();

    int p = read_uint8(in);

    protocol = p == 6 ? portmap_protocol::tcp

      : portmap_protocol::udp;

    in += 3; // reserved

  }

  int const private_port = read_uint16(in);

  int const public_port = read_uint16(in);

  if (version == version_natpmp)

    lifetime = aux::numeric_cast<int>(read_uint32(in));

  address external_addr;

  if (version == version_pcp)

  {

    external_addr = read_v6_address(in);

    if (external_addr.to_v6().is_v4_mapped())

      external_addr = make_address_v4(v4_mapped, external_addr.to_v6());

  }

  if (version == version_natpmp)

  {

    protocol = (cmd - 128 == 1)

      ? portmap_protocol::udp

      : portmap_protocol::tcp;

  }

#ifndef TORRENT_DISABLE_LOGGING

  char msg[200];

  int const num_chars = std::snprintf(msg, sizeof(msg), "<== port map ["

    " transport: %s protocol: %s local: %d external: %d ttl: %d ]"

    , version_to_string(protocol_version(version))

    , (protocol == portmap_protocol::udp ? "udp" : "tcp")

    , private_port, public_port, lifetime);

#endif

  mapping_t* m = nullptr;

  port_mapping_t index{-1};

  for (auto 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;

    if (version == version_pcp && nonce != i->nonce) continue;

    m = &*i;

    index = port_mapping_t(static_cast<int>(i - m_mappings.begin()));

    break;

  }

  if (m == nullptr)

  {

#ifndef TORRENT_DISABLE_LOGGING

    snprintf(msg + num_chars, sizeof(msg) - aux::numeric_cast<std::size_t>(num_chars), " not found in map table");

    log("%s", msg);

#endif

    return;

  }

  m->outstanding_request = false;

#ifndef TORRENT_DISABLE_LOGGING

  log("%s", msg);

#endif

  if (public_port == 0 || lifetime == 0)

  {

    // this means the mapping was

    // successfully closed

    m->protocol = portmap_protocol::none;

  }

  else

  {

    m->expires = aux::time_now() + seconds(lifetime * 3 / 4);

    m->external_port = public_port;

    if (!external_addr.is_unspecified())

      m->external_address = external_addr;

  }

  if (result != 0)

  {

    m->expires = aux::time_now() + hours(2);

    portmap_protocol const proto = m->protocol;

    m_callback.on_port_mapping(port_mapping_t{index}, address(), 0, proto

      , from_result_code(version, result), portmap_transport::natpmp, m_listen_handle);

  }

  else if (m->act == portmap_action::add)

  {

    portmap_protocol const proto = m->protocol;

    address const ext_ip = version == version_pcp ? m->external_address : m_external_ip;

    m_callback.on_port_mapping(port_mapping_t{index}, ext_ip, m->external_port, proto

      , errors::pcp_success, portmap_transport::natpmp, m_listen_handle);

  }

  m_currently_mapping = port_mapping_t{-1};

  m->act = portmap_action::none;

  m_send_timer.cancel();

  update_expiration_timer();

  try_next_mapping(index);

}

void natpmp::update_expiration_timer()

{

  TORRENT_ASSERT(is_single_thread());

  if (m_abort) return;

  time_point const now = aux::time_now() + milliseconds(100);

  time_point min_expire = now + seconds(3600);

  port_mapping_t min_index{-1};

  for (auto i = m_mappings.begin(), end(m_mappings.end()); i != end; ++i)

  {

    if (i->protocol == portmap_protocol::none

      || i->act != portmap_action::none) continue;

    port_mapping_t const index(static_cast<int>(i - m_mappings.begin()));

    if (i->expires < now)

    {

#ifndef TORRENT_DISABLE_LOGGING

      log("mapping %d expired", static_cast<int>(index));

#endif

      i->act = portmap_action::add;

      if (m_next_refresh == index) m_next_refresh = port_mapping_t{-1};

      update_mapping(index);

    }

    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 >= port_mapping_t{})

  {

#ifndef TORRENT_DISABLE_LOGGING

    log("next expiration [ idx: %d ttl: %" PRId64 " ]"

      , static_cast<int>(min_index), total_seconds(min_expire - aux::time_now()));

#endif

    if (m_next_refresh >= port_mapping_t{}) m_refresh_timer.cancel();

    ADD_OUTSTANDING_ASYNC("natpmp::mapping_expired");

    m_refresh_timer.expires_after(min_expire - now);

    m_refresh_timer.async_wait(std::bind(&natpmp::mapping_expired, self(), _1, min_index));

    m_next_refresh = min_index;

  }

}

void natpmp::mapping_expired(error_code const& e, port_mapping_t const i)

{

  TORRENT_ASSERT(is_single_thread());

  COMPLETE_ASYNC("natpmp::mapping_expired");

  if (e || m_abort) return;

#ifndef TORRENT_DISABLE_LOGGING

  log("mapping %d expired", static_cast<int>(i));

#endif

  m_mappings[i].act = portmap_action::add;

  if (m_next_refresh == i) m_next_refresh = port_mapping_t{-1};

  update_mapping(i);

}

void natpmp::close()

{

  TORRENT_ASSERT(is_single_thread());