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From: benny@vlss.amdahl.com (Benny Schnaider)
Newsgroups: comp.protocols.tcp-ip
Subject: Internet broadcast: INADDR_BROADCAST
Message-ID: <BENNY.91Apr10110956@dimona.vlss.amdahl.com>
Date: 10 Apr 91 18:09:56 GMT
Sender: netnews@ccc.amdahl.com
Distribution: comp
Organization: Amdahl Corp., Sunnyvale CA
Lines: 87

Hi,

I am trying to broadcast a message over the internet by using the
INADDR_BROADCAST shorthand notation. I tried this on SunOS 4.01
and got: Network is unreachable... On other system that I tried
the same code it worked.
Code is enclosed.

1. What is the problem ?
2. How common is it to use INADDR_BROADCAST ?

Thanks,
Benny.

____________________________________________________________________________

  int sd, on;
  struct sockaddr_in sockAddr;

  /*
   * zero out the socket structures
   */
  bzero(&sockAddr, sizeof(sockAddr));

  /*
   * Open the socket
   */
  if ((sd = socket(AF_INET, SOCK_DGRAM, 0)) == -1) {
    close(sd);
    BPCerror(LOG_WARNING, "in socket creation (request)");
    return(ERROR);
  }
 
  /*
   * Mark the socket to allow broadcast.
   */
  on = 1;
  if ((setsockopt(sd, SOL_SOCKET, SO_BROADCAST, &on, sizeof(on))) == -1) {
    close(sd);
    BPCerror(LOG_WARNING, "in SO_BROADCAST");
    return(ERROR);
  }

  /*
   * Fill sockAddrAs
   */
  sockAddr.sin_family       = AF_INET;
  sockAddr.sin_port         = IPPORT_BOOTPS;
  sockAddr.sin_addr.s_addr  = INADDR_ANY;

  /*
   * Bind the socket
   */
  if (bind(sd, &sockAddr, sizeof(sockAddr)) == -1) {
    close(sd);
    BPCerror(LOG_WARNING, "in socket binding (request)");
    return(ERROR);
  }

  /*
   * Broadcast the request
   */
  sockAddr.sin_addr.s_addr  = INADDR_BROADCAST;
  if (sendto(sd, msg, sizeof(*msg), 0, &sockAddr, sizeof(sockAddr)) == -1) {
    close(sd);
    BPCerror(LOG_WARNING, "sendto");
    return(ERROR);
  } /* sendto */

  close(sd);
  return(OK);

} /* BPCrequestIP() */

-----------------------------------------------------------------
Benny Schnaider    benny@vlss.amdahl.com
                   Amdahl Corporation, 1250 EAST Arques Avenue,
                   M/S 246, Sunnyvale CA, 94088-3470
                   (408) 296 - 0596, (408) 746-3440
-----------------------------------------------------------------
--
-----------------------------------------------------------------
Benny Schnaider    benny@vlss.amdahl.com
                   Amdahl Corporation, 1250 EAST Arques Avenue,
                   M/S 246, Sunnyvale CA, 94088-3470
                   (408) 296 - 0596, (408) 746-3440
-----------------------------------------------------------------