reactive_socket_service.hpp

Boost provides free peer-reviewed portable C++ source libraries. We emphasize libraries that work

      // implementation is not updated unless the ioctl operation succeeds.
      unsigned char new_flags = impl.flags_;
      if (command.get())
        new_flags |= implementation_type::user_set_non_blocking;
      else
        new_flags &= ~implementation_type::user_set_non_blocking;

      // Perform ioctl on socket if the non-blocking state has changed.
      if (!(impl.flags_ & implementation_type::non_blocking)
          && (new_flags & implementation_type::non_blocking))
      {
        ioctl_arg_type non_blocking = 1;
        socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec);
      }
      else if ((impl.flags_ & implementation_type::non_blocking)
          && !(new_flags & implementation_type::non_blocking))
      {
        ioctl_arg_type non_blocking = 0;
        socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec);
      }
      else
      {
        ec = boost::system::error_code();
      }

      // Update socket implementation's flags only if successful.
      if (!ec)
        impl.flags_ = new_flags;
    }
    else
    {
      socket_ops::ioctl(impl.socket_, command.name(),
          static_cast<ioctl_arg_type*>(command.data()), ec);
    }
    return ec;
  }

  // Get the local endpoint.
  endpoint_type local_endpoint(const implementation_type& impl,
      boost::system::error_code& ec) const
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return endpoint_type();
    }

    endpoint_type endpoint;
    std::size_t addr_len = endpoint.capacity();
    if (socket_ops::getsockname(impl.socket_, endpoint.data(), &addr_len, ec))
      return endpoint_type();
    endpoint.resize(addr_len);
    return endpoint;
  }

  // Get the remote endpoint.
  endpoint_type remote_endpoint(const implementation_type& impl,
      boost::system::error_code& ec) const
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return endpoint_type();
    }

    endpoint_type endpoint;
    std::size_t addr_len = endpoint.capacity();
    if (socket_ops::getpeername(impl.socket_, endpoint.data(), &addr_len, ec))
      return endpoint_type();
    endpoint.resize(addr_len);
    return endpoint;
  }

  /// Disable sends or receives on the socket.
  boost::system::error_code shutdown(implementation_type& impl,
      socket_base::shutdown_type what, boost::system::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return ec;
    }

    socket_ops::shutdown(impl.socket_, what, ec);
    return ec;
  }

  // Send the given data to the peer.
  template <typename ConstBufferSequence>
  size_t send(implementation_type& impl, const ConstBufferSequence& buffers,
      socket_base::message_flags flags, boost::system::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return 0;
    }

    // Copy buffers into array.
    socket_ops::buf bufs[max_buffers];
    typename ConstBufferSequence::const_iterator iter = buffers.begin();
    typename ConstBufferSequence::const_iterator end = buffers.end();
    size_t i = 0;
    size_t total_buffer_size = 0;
    for (; iter != end && i < max_buffers; ++iter, ++i)
    {
      boost::asio::const_buffer buffer(*iter);
      socket_ops::init_buf(bufs[i],
          boost::asio::buffer_cast<const void*>(buffer),
          boost::asio::buffer_size(buffer));
      total_buffer_size += boost::asio::buffer_size(buffer);
    }

    // A request to receive 0 bytes on a stream socket is a no-op.
    if (impl.protocol_.type() == SOCK_STREAM && total_buffer_size == 0)
    {
      ec = boost::system::error_code();
      return 0;
    }

    // Send the data.
    for (;;)
    {
      // Try to complete the operation without blocking.
      int bytes_sent = socket_ops::send(impl.socket_, bufs, i, flags, ec);

      // Check if operation succeeded.
      if (bytes_sent >= 0)
        return bytes_sent;

      // Operation failed.
      if ((impl.flags_ & implementation_type::user_set_non_blocking)
          || (ec != boost::asio::error::would_block
            && ec != boost::asio::error::try_again))
        return 0;

      // Wait for socket to become ready.
      if (socket_ops::poll_write(impl.socket_, ec) < 0)
        return 0;
    }
  }

  // Wait until data can be sent without blocking.
  size_t send(implementation_type& impl, const null_buffers&,
      socket_base::message_flags, boost::system::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return 0;
    }

    // Wait for socket to become ready.
    socket_ops::poll_write(impl.socket_, ec);

    return 0;
  }

  template <typename ConstBufferSequence, typename Handler>
  class send_operation :
    public handler_base_from_member<Handler>
  {
  public:
    send_operation(socket_type socket, boost::asio::io_service& io_service,
        const ConstBufferSequence& buffers, socket_base::message_flags flags,
        Handler handler)
      : handler_base_from_member<Handler>(handler),
        socket_(socket),
        io_service_(io_service),
        work_(io_service),
        buffers_(buffers),
        flags_(flags)
    {
    }

    bool perform(boost::system::error_code& ec,
        std::size_t& bytes_transferred)
    {
      // Check whether the operation was successful.
      if (ec)
      {
        bytes_transferred = 0;
        return true;
      }

      // Copy buffers into array.
      socket_ops::buf bufs[max_buffers];
      typename ConstBufferSequence::const_iterator iter = buffers_.begin();
      typename ConstBufferSequence::const_iterator end = buffers_.end();
      size_t i = 0;
      for (; iter != end && i < max_buffers; ++iter, ++i)
      {
        boost::asio::const_buffer buffer(*iter);
        socket_ops::init_buf(bufs[i],
            boost::asio::buffer_cast<const void*>(buffer),
            boost::asio::buffer_size(buffer));
      }

      // Send the data.
      int bytes = socket_ops::send(socket_, bufs, i, flags_, ec);

      // Check if we need to run the operation again.
      if (ec == boost::asio::error::would_block
          || ec == boost::asio::error::try_again)
        return false;

      bytes_transferred = (bytes < 0 ? 0 : bytes);
      return true;
    }

    void complete(const boost::system::error_code& ec,
        std::size_t bytes_transferred)
    {
      io_service_.post(bind_handler(this->handler_, ec, bytes_transferred));
    }

  private:
    socket_type socket_;
    boost::asio::io_service& io_service_;
    boost::asio::io_service::work work_;
    ConstBufferSequence buffers_;
    socket_base::message_flags flags_;
  };

  // Start an asynchronous send. The data being sent must be valid for the
  // lifetime of the asynchronous operation.
  template <typename ConstBufferSequence, typename Handler>
  void async_send(implementation_type& impl, const ConstBufferSequence& buffers,
      socket_base::message_flags flags, Handler handler)
  {
    if (!is_open(impl))
    {
      this->get_io_service().post(bind_handler(handler,
            boost::asio::error::bad_descriptor, 0));
    }
    else
    {
      if (impl.protocol_.type() == SOCK_STREAM)
      {
        // Determine total size of buffers.
        typename ConstBufferSequence::const_iterator iter = buffers.begin();
        typename ConstBufferSequence::const_iterator end = buffers.end();
        size_t i = 0;
        size_t total_buffer_size = 0;
        for (; iter != end && i < max_buffers; ++iter, ++i)
        {
          boost::asio::const_buffer buffer(*iter);
          total_buffer_size += boost::asio::buffer_size(buffer);
        }

        // A request to receive 0 bytes on a stream socket is a no-op.
        if (total_buffer_size == 0)
        {
          this->get_io_service().post(bind_handler(handler,
                boost::system::error_code(), 0));
          return;
        }
      }

      // Make socket non-blocking.
      if (!(impl.flags_ & implementation_type::internal_non_blocking))
      {
        if (!(impl.flags_ & implementation_type::non_blocking))
        {
          ioctl_arg_type non_blocking = 1;
          boost::system::error_code ec;
          if (socket_ops::ioctl(impl.socket_, FIONBIO, &non_blocking, ec))
          {
            this->get_io_service().post(bind_handler(handler, ec, 0));
            return;
          }
        }
        impl.flags_ |= implementation_type::internal_non_blocking;
      }

      reactor_.start_write_op(impl.socket_, impl.reactor_data_,
          send_operation<ConstBufferSequence, Handler>(
            impl.socket_, this->get_io_service(), buffers, flags, handler));
    }
  }

  template <typename Handler>
  class null_buffers_operation :
    public handler_base_from_member<Handler>
  {
  public:
    null_buffers_operation(boost::asio::io_service& io_service, Handler handler)
      : handler_base_from_member<Handler>(handler),
        work_(io_service)
    {
    }

    bool perform(boost::system::error_code&,
        std::size_t& bytes_transferred)
    {
      bytes_transferred = 0;
      return true;
    }

    void complete(const boost::system::error_code& ec,
        std::size_t bytes_transferred)
    {
      work_.get_io_service().post(bind_handler(
            this->handler_, ec, bytes_transferred));
    }

  private:
    boost::asio::io_service::work work_;
  };

  // Start an asynchronous wait until data can be sent without blocking.
  template <typename Handler>
  void async_send(implementation_type& impl, const null_buffers&,
      socket_base::message_flags, Handler handler)
  {
    if (!is_open(impl))
    {
      this->get_io_service().post(bind_handler(handler,
            boost::asio::error::bad_descriptor, 0));
    }
    else
    {
      reactor_.start_write_op(impl.socket_, impl.reactor_data_,
          null_buffers_operation<Handler>(this->get_io_service(), handler),
          false);
    }
  }

  // Send a datagram to the specified endpoint. Returns the number of bytes
  // sent.
  template <typename ConstBufferSequence>
  size_t send_to(implementation_type& impl, const ConstBufferSequence& buffers,
      const endpoint_type& destination, socket_base::message_flags flags,
      boost::system::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return 0;
    }

    // Copy buffers into array.
    socket_ops::buf bufs[max_buffers];
    typename ConstBufferSequence::const_iterator iter = buffers.begin();
    typename ConstBufferSequence::const_iterator end = buffers.end();
    size_t i = 0;
    for (; iter != end && i < max_buffers; ++iter, ++i)
    {
      boost::asio::const_buffer buffer(*iter);
      socket_ops::init_buf(bufs[i],
          boost::asio::buffer_cast<const void*>(buffer),
          boost::asio::buffer_size(buffer));
    }

    // Send the data.
    for (;;)
    {
      // Try to complete the operation without blocking.
      int bytes_sent = socket_ops::sendto(impl.socket_, bufs, i, flags,
          destination.data(), destination.size(), ec);

      // Check if operation succeeded.
      if (bytes_sent >= 0)
        return bytes_sent;

      // Operation failed.
      if ((impl.flags_ & implementation_type::user_set_non_blocking)
          || (ec != boost::asio::error::would_block
            && ec != boost::asio::error::try_again))
        return 0;

      // Wait for socket to become ready.
      if (socket_ops::poll_write(impl.socket_, ec) < 0)
        return 0;
    }
  }

  // Wait until data can be sent without blocking.
  size_t send_to(implementation_type& impl, const null_buffers&,
      socket_base::message_flags, const endpoint_type&,
      boost::system::error_code& ec)
  {
    if (!is_open(impl))
    {
      ec = boost::asio::error::bad_descriptor;
      return 0;
    }

    // Wait for socket to become ready.
    socket_ops::poll_write(impl.socket_, ec);

    return 0;
  }

  template <typename ConstBufferSequence, typename Handler>
  class send_to_operation :
    public handler_base_from_member<Handler>
  {
  public:
    send_to_operation(socket_type socket, boost::asio::io_service& io_service,
        const ConstBufferSequence& buffers, const endpoint_type& endpoint,
        socket_base::message_flags flags, Handler handler)
      : handler_base_from_member<Handler>(handler),
        socket_(socket),
        io_service_(io_service),
        work_(io_service),
        buffers_(buffers),
        destination_(endpoint),
        flags_(flags)
    {
    }

    bool perform(boost::system::error_code& ec,
        std::size_t& bytes_transferred)
    {
      // Check whether the operation was successful.
      if (ec)
      {
        bytes_transferred = 0;
        return true;
      }

      // Copy buffers into array.
      socket_ops::buf bufs[max_buffers];
      typename ConstBufferSequence::const_iterator iter = buffers_.begin();
      typename ConstBufferSequence::const_iterator end = buffers_.end();
      size_t i = 0;
      for (; iter != end && i < max_buffers; ++iter, ++i)
      {
        boost::asio::const_buffer buffer(*iter);
        socket_ops::init_buf(bufs[i],
            boost::asio::buffer_cast<const void*>(buffer),
            boost::asio::buffer_size(buffer));
      }

      // Send the data.
      int bytes = socket_ops::sendto(socket_, bufs, i, flags_,
          destination_.data(), destination_.size(), ec);

      // Check if we need to run the operation again.
      if (ec == boost::asio::error::would_block
          || ec == boost::asio::error::try_again)
        return false;

      bytes_transferred = (bytes < 0 ? 0 : bytes);
      return true;
    }