/*
  Example UDP client.
  Copyright (C) 2005 Russell Bradford

  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 (http://www.gnu.org/copyleft/gpl.html)
  for more details. 
*/

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <string.h>

#define PORT 12345
#define MESSAGE "hi there"
#define SERVADDR "127.0.0.1"

int main(void)
{
  int sock;
  socklen_t clilen;
  struct sockaddr_in server_addr, client_addr;
  char buffer[1024];

  /* create a DGRAM (UDP) socket in the INET (IP) protocol */
  sock = socket(PF_INET, SOCK_DGRAM, 0);

  if (sock < 0) {
    perror("creating socket");
    exit(1);
  }

  /* create server address: where we want to send to */

  /* clear it out */
  memset(&server_addr, 0, sizeof(server_addr));

  /* it is an INET address */
  server_addr.sin_family = AF_INET;

  /* the server IP address, in network byte order */
  inet_aton(SERVADDR, &server_addr.sin_addr);

  /* the port we are going to send to, in network byte order */
  server_addr.sin_port = htons(PORT);

  /* now send a datagram */
  if (sendto(sock, MESSAGE, sizeof(MESSAGE), 0,
             (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) {
      perror("sendto failed");
      exit(4);
  }

  printf("waiting for a reply...\n");
  clilen = sizeof(client_addr);
  if (recvfrom(sock, buffer, 1024, 0, (struct sockaddr *)&client_addr,
               &clilen) < 0) {
      perror("recvfrom failed");
      exit(4);
  }

  printf("got '%s' from %s\n", buffer, inet_ntoa(client_addr.sin_addr));

  /* close socket */
  close(sock);

  return 0;
}