udp_printf_client.c

   1
   2 /*
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; version 2 of the License.
   6  *
   7  * This program is distributed in the hope that it will be useful,
   8  * but WITHOUT ANY WARRANTY; without even the implied warranty of
   9  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  10  * GNU General Public License for more details.
  11  *
  12  * You should have received a copy of the GNU General Public License
  13  * along with this program; if not, write to the Free Software
  14  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  15  */
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <unistd.h>
  21 #include <sys/types.h>
  22 #include <sys/socket.h>
  23 #include <netinet/in.h>
  24 #include <arpa/inet.h>
  25
  26 #define UDP_PRINTF_DEFAULT_PORT         9999
  27
  28 /*
  29  * usage
  30  */
  31 static void usage(const char *progname)
  32 {
  33         fprintf(stderr, "usage: %s [port]\n", progname);
  34
  35         exit(1);
  36 }
  37
  38 /*
  39  * main
  40  */
  41 int main(int argc, char **argv)
  42 {
  43         char *endptr;
  44         int port, sock, error, n;
  45         struct sockaddr_in sockaddr;
  46         char buf[4096];
  47
  48         port = UDP_PRINTF_DEFAULT_PORT;
  49
  50         if (argc > 1) {
  51                 port = strtol(argv[1], &endptr, 0);
  52                 if ((*endptr != '\0') || (port < 0) || (port > 65535))
  53                         usage(argv[0]);
  54         }
  55
  56         sock = socket(PF_INET, SOCK_DGRAM, IPPROTO_UDP);
  57         if (sock < 0) {
  58                 perror("bind");
  59                 return 1;
  60         }
  61
  62         memset(&sockaddr, 0, sizeof(sockaddr));
  63         sockaddr.sin_family = AF_INET;
  64         sockaddr.sin_addr.s_addr = INADDR_ANY;
  65         sockaddr.sin_port = htons(port);
  66
  67         error = bind(sock, (const struct sockaddr*) &sockaddr, sizeof(sockaddr));
  68         if (error) {
  69                 perror("bind");
  70                 return 1;
  71         }
  72
  73         while (1) {
  74                 n = read(sock, buf, sizeof(buf) - 1);
  75                 if (n <= 0)
  76                         continue;
  77
  78                 buf[n] = 0;
  79
  80                 fprintf(stdout, buf, strlen(buf));
  81                 fflush(stdout);
  82         }
  83
  84         return 0;
  85 }