udp_socket.hpp

#pragma once
#include <ossia/detail/logger.hpp>
#include <ossia/network/sockets/configuration.hpp>
#include <ossia/network/sockets/writers.hpp>
 
#include <boost/asio/io_context.hpp>
#include <boost/asio/ip/multicast.hpp>
#include <boost/asio/ip/udp.hpp>
#include <boost/asio/local/datagram_protocol.hpp>
#include <boost/asio/placeholders.hpp>
#include <boost/asio/strand.hpp>
#include <boost/asio/write.hpp>
 
#if !defined(_WIN32)
#include <sys/socket.h>
#endif
 
#include <nano_signal_slot.hpp>
 
namespace ossia::net
{
 
class udp_receive_socket
{
  using proto = boost::asio::ip::udp;
 
public:
  udp_receive_socket(boost::asio::io_context& ctx)
      : m_context{ctx}
      , m_socket{boost::asio::make_strand(ctx)}
  {
  }
 
  udp_receive_socket(const inbound_socket_configuration& conf, boost::asio::io_context& ctx)
      : m_context{ctx}
      , m_endpoint{boost::asio::ip::make_address(conf.bind), conf.port}
      , m_socket{boost::asio::make_strand(ctx)}
      , m_multicast_group{conf.multicast_group}
      , m_multicast_interface{conf.multicast_interface}
  {
  }
 
  ~udp_receive_socket() = default;
 
  void assign(int sock) { m_socket.assign(boost::asio::ip::udp::v4(), sock); }
  void open()
  {
#if defined(__EMSCRIPTEN__)
    // A browser has no way to bind a port.
    return;
#else
    m_socket.open(boost::asio::ip::udp::v4());
    if(!m_multicast_group.empty())
    {
      m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
#if defined(SO_REUSEPORT)
      // macOS / *BSD require SO_REUSEPORT in addition to SO_REUSEADDR for
      // multiple processes to share a multicast port. On Linux it's harmless
      // (kernel allows it for multicast). Windows has no SO_REUSEPORT.
      using reuse_port
          = boost::asio::detail::socket_option::boolean<SOL_SOCKET, SO_REUSEPORT>;
      boost::system::error_code ec;
      m_socket.set_option(reuse_port(true), ec);
#endif
    }
    m_socket.bind(m_endpoint);
    if(!m_multicast_group.empty())
    {
      const auto group = boost::asio::ip::make_address_v4(m_multicast_group);
      const auto iface = boost::asio::ip::make_address_v4(m_multicast_interface);
      m_socket.set_option(boost::asio::ip::multicast::join_group(group, iface));
    }
#endif
  }
 
  void close()
  {
    // Posts a lambda that can run after the socket is gone: the usual shutdown
    // is close() followed by dropping the owner.
    if(m_socket.is_open())
    {
      boost::asio::post(m_context, [this, alive = m_lifetime.watch()] {
        if(alive.expired())
          return;
 
        try
        {
          m_socket.shutdown(boost::asio::ip::udp::socket::shutdown_both);
        }
        catch(...)
        {
        }
 
        m_socket.close();
        on_close();
      });
    }
  }
 
  template <typename F>
  void receive(F f)
  {
#if defined(__EMSCRIPTEN__)
    (void)f;
    return;
#else
    m_socket.async_receive_from(
        boost::asio::mutable_buffer(&m_data[0], std::size(m_data)), m_endpoint,
        [this, f](auto ec, std::size_t sz) {
      if(ec == boost::asio::error::operation_aborted)
        return;
 
      if(!ec && sz > 0)
      {
        try
        {
          f(m_data, sz);
        }
        catch(const std::exception& e)
        {
          ossia::logger().error("[udp_socket::receive]: {}", e.what());
        }
        catch(...)
        {
          ossia::logger().error("[udp_socket::receive]: unknown error");
        }
      }
 
      this->receive(f);
        });
#endif
  }
 
  Nano::Signal<void()> on_close;
 
  boost::asio::io_context& m_context;
  proto::endpoint m_endpoint;
  proto::socket m_socket;
  std::string m_multicast_group;
  std::string m_multicast_interface;
  alignas(16) char m_data[65535];
  lifetime_token m_lifetime;
};
 
class udp_send_socket
{
  using proto = boost::asio::ip::udp;
 
public:
  udp_send_socket(const outbound_socket_configuration& conf, boost::asio::io_context& ctx)
      : m_context{ctx}
      , m_endpoint{boost::asio::ip::make_address(conf.host), conf.port}
      , m_socket{boost::asio::make_strand(ctx)}
      , m_broadcast{conf.broadcast}
      , m_multicast_ttl{conf.multicast_ttl}
      , m_multicast_interface{conf.multicast_interface}
      , m_multicast_loopback{conf.multicast_loopback}
  {
  }
 
  udp_send_socket(
      const boost::asio::ip::address& host, const uint16_t port,
      boost::asio::io_context& ctx)
      : m_context{ctx}
      , m_endpoint{host, port}
      , m_socket{boost::asio::make_strand(ctx)}
  {
  }
 
  void connect()
  {
#if defined(__EMSCRIPTEN__)
    return;
#else
    m_socket.open(boost::asio::ip::udp::v4());
 
    m_socket.set_option(boost::asio::ip::udp::socket::reuse_address(true));
 
    if(m_broadcast)
      m_socket.set_option(boost::asio::socket_base::broadcast(true));
 
    if(m_endpoint.address().is_multicast())
    {
      if(m_multicast_ttl)
        m_socket.set_option(boost::asio::ip::multicast::hops(*m_multicast_ttl));
      if(!m_multicast_interface.empty())
      {
        m_socket.set_option(boost::asio::ip::multicast::outbound_interface(
            boost::asio::ip::make_address_v4(m_multicast_interface)));
      }
      if(m_multicast_loopback)
      {
        m_socket.set_option(
            boost::asio::ip::multicast::enable_loopback(*m_multicast_loopback));
      }
    }
#endif
  }
 
  void close()
  {
    // Same as udp_receive_socket::close(): the posted lambda outlives us.
    if(m_socket.is_open())
    {
      boost::asio::post(m_context, [this, alive = m_lifetime.watch()] {
        if(alive.expired())
          return;
 
        try
        {
          m_socket.shutdown(boost::asio::ip::udp::socket::shutdown_both);
        }
        catch(...)
        {
        }
        m_socket.close();
        on_close();
      });
    }
  }
 
  void write(const proto::endpoint& ep, const char* data, std::size_t sz)
  {
    boost::system::error_code ec;
    m_socket.send_to(boost::asio::const_buffer(data, sz), ep, 0, ec);
  }
 
  void write(const char* data, std::size_t sz) { write(m_endpoint, data, sz); }
 
  Nano::Signal<void()> on_close;
 
  boost::asio::io_context& m_context;
  proto::endpoint m_endpoint;
  proto::socket m_socket;
  bool m_broadcast{};
  std::optional<int> m_multicast_ttl;
  std::string m_multicast_interface;
  std::optional<bool> m_multicast_loopback;
  lifetime_token m_lifetime;
};
 
}