can you set SO_RCVTIMEO and SO_SNDTIMEO socket options in boost asio?

Question

can you set SO_RCVTIMEO and SO_SNDTIMEO socket options in boost asio?

If so how?

Note I know you can use timers instead, but I'd like to know about these socket options in particular.

Answer 1

Absolutely! Boost ASIO allows you to access the native/underlying data, which in this case is the SOCKET itself. So, let's say you have:

boost::asio::ip::tcp::socket my_socket;

And let's say you've already called open or bind or some member function that actually makes my_socket usable. Then, to get the underlying SOCKET value, call:

SOCKET native_sock = my_socket.native();
int result = SOCKET_ERROR;

if (INVALID_SOCKET != native_sock)
{
    result = setsockopt(native_sock, SOL_SOCKET, <the pertinent params you want to use>);
}

So there you have it! Boost's ASIO lets you do many things more quickly than you otherwise might be able to, but there are a lot of things you still need the normal socket library calls for. This happens to be one of them.

Answer 2

It doesn't appear to be built into Boost.Asio (as of current Boost SVN), but, if you're willing to write your own classes to simulate the boost::asio::detail::socket_option ones, you can always follow the examples in boost/asio/socket_base.hpp and do the following:

typedef boost::asio::detail::socket_option::timeval<SOL_SOCKET, SO_SNDTIMEO>
    send_timeout;
typedef boost::asio::detail::socket_option::timeval<SOL_SOCKET, SO_RCVTIMEO>
    receive_timeout;

(Obviously, I'm not suggesting you inject the timeval class into the boost::asio::detail::socket_option namespace, but I can't think of a good one to use at the moment. :-P)

Edit: My sample implementation of socket_option::timeval, based on socket_option::integer:

// Helper template for implementing timeval options.
template <int Level, int Name>
class timeval
{
public:
  // Default constructor.
  timeval()
    : value_(zero_timeval())
  {
  }

  // Construct with a specific option value.
  explicit timeval(::timeval v)
    : value_(v)
  {
  }

  // Set the value of the timeval option.
  timeval& operator=(::timeval v)
  {
    value_ = v;
    return *this;
  }

  // Get the current value of the timeval option.
  ::timeval value() const
  {
    return value_;
  }

  // Get the level of the socket option.
  template <typename Protocol>
  int level(const Protocol&) const
  {
    return Level;
  }

  // Get the name of the socket option.
  template <typename Protocol>
  int name(const Protocol&) const
  {
    return Name;
  }

  // Get the address of the timeval data.
  template <typename Protocol>
  ::timeval* data(const Protocol&)
  {
    return &value_;
  }

  // Get the address of the timeval data.
  template <typename Protocol>
  const ::timeval* data(const Protocol&) const
  {
    return &value_;
  }

  // Get the size of the timeval data.
  template <typename Protocol>
  std::size_t size(const Protocol&) const
  {
    return sizeof(value_);
  }

  // Set the size of the timeval data.
  template <typename Protocol>
  void resize(const Protocol&, std::size_t s)
  {
    if (s != sizeof(value_))
      throw std::length_error("timeval socket option resize");
  }

private:
  static ::timeval zero_timeval()
  {
    ::timeval result = {};
    return result;
  }

  ::timeval value_;
};