src/tests/kits/net/sock/multicast.c

   1 /* -*- c-basic-offset: 8; -*-
   2  *
   3  * Copyright (c) 1993 W. Richard Stevens.  All rights reserved.
   4  * Permission to use or modify this software and its documentation only for
   5  * educational purposes and without fee is hereby granted, provided that
   6  * the above copyright notice appear in all copies.  The author makes no
   7  * representations about the suitability of this software for any purpose.
   8  * It is provided "as is" without express or implied warranty.
   9  */
  10
  11 #include        "sock.h"
  12
  13 void
  14 join_mcast(int fd, struct sockaddr_in *sin)
  15 {
  16 #ifdef  IP_ADD_MEMBERSHIP       /* only include if host supports mcasting */
  17         u_long                  inaddr;
  18         struct ip_mreq  mreq;
  19
  20         inaddr = sin->sin_addr.s_addr;
  21         if (IN_MULTICAST(inaddr) == 0)
  22                 return;                 /* not a multicast address */
  23
  24         mreq.imr_multiaddr.s_addr = inaddr;
  25         mreq.imr_interface.s_addr = htonl(INADDR_ANY);  /* need way to change */
  26         if (setsockopt(fd, IPPROTO_IP, IP_ADD_MEMBERSHIP, &mreq,
  27                                                                                                 sizeof(mreq)) == -1 )
  28                 err_sys("IP_ADD_MEMBERSHIP error");
  29
  30         if (verbose)
  31                         fprintf(stderr, "multicast group joined\n");
  32 #endif  /* IP_ADD_MEMBERSHIP */
  33 }