Port Problem

[matmil]

I am currently sending out UDP traffic on a random port by using:-

local.sin_family = AF_INET;
local.sin_addr.s_addr = htonl(INADDR_ANY);
local.sin_port = htons(0);

As you know this picks a random, unused port to send traffic from...

I then want to listen on that port which was randomly selected for return traffic...

How can I get which port the computer randomly chose as local.sinp_port always remains 0.

Cheers,
Matt

 

[Gafling]

MatMIl:
you can use 'getsockname' to retreive that info ...

struct sockaddr_in cli_addr;    /* client socket stuff */

  /*
   * Since the connect call assigns a random address to the local end
   * of this connection, let's use 'getsockname' to see what it assigned.
   * Note that 'addrlen' needs to be passed in as a pointer, because
   * getsockname returns the actual length of the address.
   */
    climsglen = sizeof(cli_addr);
    if (getsockname(clisocket, (struct sockaddr *) &cli_addr, &climsglen)) {
        perror("getsockname");
    }

   /*
    * The port number must be converted first to host byte order before
    * printing.  On most hosts, this is not necessary, but the ntohs() call
    * is included here so that this program could easily be ported to a different host.
    */
    log_msg("Connected to %s on port %u.", hostname, ntohs(cli_addr.sin_port));