/*
    $Id: aprs-udp-rx.c,v 1.1 2005/08/10 12:10:10 james Exp james $

    udplx, listener, displays what is sent only
    Copyright (C) 2005 James Cameron <quozl@us.netrek.org>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

#ifndef lint
static char vcid[] = "$Id: aprs-udp-rx.c,v 1.1 2005/08/10 12:10:10 james Exp james $";
#endif /* lint */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <netdb.h>

int main (int argc, char *argv[])
{
  unsigned short port;
  char *host;
  char *var;
  int subs = 1;
  int sock;
  struct sockaddr_in address;
  int stat, len;
  char buf[BUFSIZ];

  port = 8135;
  if (argc > 1) host = argv[1];
  if (argc > 2) port = atoi(argv[2]);
  var = getenv("APRS_UDP_RX_SUBSCRIBE");
  if (var != NULL) subs = atoi(var);

  sock = socket(AF_INET, SOCK_DGRAM, 0);
  if (sock < 0) { perror("socket"); exit(1); }

  if (!subs) {
    address.sin_addr.s_addr = INADDR_ANY;
    address.sin_family = AF_INET;
    address.sin_port = htons(port);
    
    stat = bind(sock, (struct sockaddr *) &address, sizeof(address));
    if (stat < 0) { perror("bind"); exit(2); }
  }

  address.sin_family = AF_INET;
  address.sin_port = htons(port);

  if ((address.sin_addr.s_addr = inet_addr(host)) == -1) {
    struct hostent *hp;
    if ((hp = gethostbyname(host)) == NULL) {
      herror("gethostbyname");
      exit(2);
    } else {
      address.sin_addr.s_addr = *(long *) hp->h_addr;
    }
  }

  while(1) {

    if (subs) {
      /* send empty, to subscribe */
      stat = sendto(sock, buf, 0, 0, (struct sockaddr *) &address, 
		    sizeof(struct sockaddr));
      if (stat < 0) { perror("sendto"); exit(4); }
    }
    
    /* receive response */
    len = recvfrom(sock, buf, BUFSIZ, 0, NULL, NULL);
    if (len < 0) { perror("recvfrom"); exit(3); }

    if (len == 0) {
      fprintf(stderr, "subscription acknowledged\n");
    } else {
      /* display response */
      stat = write(STDOUT_FILENO, buf, len);
      if (stat < 0) { perror("write"); exit(4); }
    }

  }

  close(sock);
}