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

main(argc, argv)
int argc;
char *argv[];
{
  int s;
  int i;
  int port = 1234;
  int bufsize = 512;
  int fromlen;
  char *buf;
  char *hostname = "";
  struct hostent *host;
  struct sockaddr_in sin, from;

  while (++argv, --argc) {
    if ((*argv)[0] == '-')
      switch ((*argv)[1]) {

      case 'b':
	if ((++argv, --argc) && (i = atoi(*argv)))
	  bufsize = i;
	else {
	  fprintf(stderr, "%s: bad bufsize\n", argc ? *argv : "???");
	  exit(1);
	}	
	break;

      case 'h':
	if ((++argv, --argc))
	  hostname = *argv;
	else {
	  fprintf(stderr, "No hostname!\n");
	  exit(1);
	}	
	break;

      default:
	fprintf(stderr, "%s: bad switch\n", *argv);
	exit(1);
      }

    else {
      if (i = atoi(*argv))
	port = i;
      else {
	fprintf(stderr, "%s: bad port\n", *argv);
	exit(1);
      }
    }
  }

  if ((*hostname != '\0') &&
      (host = (struct hostent *)gethostbyname(hostname))) {
    sin.sin_family = host->h_addrtype;
    bcopy(host->h_addr, (caddr_t)&sin.sin_addr, host->h_length);
  } else {
    sin.sin_family = AF_INET;
    if (*hostname != '\0') {
      sin.sin_addr.s_addr = htonl(inet_addr(hostname));
      if (sin.sin_addr.s_addr == -1) {
	fprintf(stderr, "%s: bad hostname\n", hostname);
	exit(1);
      }
    } else {
      sin.sin_addr.s_addr = htonl(INADDR_ANY);
    }
  }
  sin.sin_port = htons(port);

  s = socket(AF_INET, SOCK_DGRAM, 0);

  if (bind(s, &sin, sizeof(struct sockaddr_in)) < 0) {
    perror("bind");
    exit(1);
  }

  buf = (char *)malloc(bufsize);

  while ((i = recvfrom(s, buf, bufsize, 0, &from, &fromlen)) > 0) {
    if (write(1, buf, i) != i) {
      perror("write");
      exit(1);
    }
  }

  if (i < 0)
    perror("recvfrom");
}