Configuring TCP keep_alive with boost::asio [duplicate]

Question

Both Linux and Windows support TCP keep-alive packets. They can be activated and configured with (system-dependent) setsockopt calls, see e.g. this article for the Linux case. When using boost::asio there appears to be support for keep-alive messages, see the current documentation. However that page only covers activating it. In several new responses to an older post it was pointed out that Boost has recently added the means to configure timeouts on operations (which obviates the need for setsockopt and #ifdef code-branches for different systems). However, a recent response still suggests calls on the native sockets.

My question is: How can I configure the time interval and timeouts of keep-alive packets using boost::asio?

Answer 1

You can configure both the send timeout and receive timeout using the setsockopt options. Here is some platform-dependent code to do this on both windows and linux / unix, the example sets both send and receive timeouts to the same ten second value:

// start IO service    
io_context = new boost::asio::io_context;        

// define a tcp socket object    
tcpsocket = new boost::asio::ip::tcp::socket(*io_context); 

// the timeout value
unsigned int timeout_milli = 10000;

// platform-specific switch
#if defined _WIN32 || defined WIN32 || defined OS_WIN64 || defined _WIN64 || defined WIN64 || defined WINNT
  // use windows-specific time
  int32_t timeout = timeout_milli;
  setsockopt(tcpsocket->native_handle(), SOL_SOCKET, SO_RCVTIMEO, (const char*)&timeout, sizeof(timeout));
  setsockopt(tcpsocket->native_handle(), SOL_SOCKET, SO_SNDTIMEO, (const char*)&timeout, sizeof(timeout));
#else
  // assume everything else is posix
  struct timeval tv;
  tv.tv_sec  = timeout_milli / 1000;
  tv.tv_usec = (timeout_milli % 1000) * 1000;
  setsockopt(tcpsocket->native_handle(), SOL_SOCKET, SO_RCVTIMEO, &tv, sizeof(tv));
  setsockopt(tcpsocket->native_handle(), SOL_SOCKET, SO_SNDTIMEO, &tv, sizeof(tv));
#endif