dgramrcv.c

   1 /* dgramrcv.c - receive from udp server
   2  *
   3  * author: hackbard
   4  *
   5  */
   6
   7 #include <stdio.h>
   8 #include <stdlib.h>
   9
  10 /* memset */
  11 #include <string.h>
  12
  13 /* socket and bind stuff */
  14 #include <sys/types.h>
  15 #include <sys/socket.h>
  16
  17 /* sockkaddr_in */
  18 #include <netinet/in.h>
  19
  20 /* inet_ntoa ... */
  21 #include <arpa/inet.h>
  22
  23 /* errno stuff ... */
  24 #include <errno.h>
  25
  26 /* read, close */
  27 #include <unistd.h>
  28
  29 int main(int argc, char *argv[]) {
  30   int receive_fd;
  31   int opt;
  32   struct sockaddr_in local_addr,target_addr;
  33   int receive_bytes, write_bytes;
  34   socklen_t target_addr_len;
  35
  36   if(argc!=2) {
  37     printf("usage: %s <port>\n",argv[0]);
  38     exit(1);
  39   }
  40
  41   if((receive_fd=socket(AF_INET,SOCK_DGRAM,0)) == -1) {
  42     printf("can't open socket.\n");
  43     exit(1);
  44   }
  45
  46   opt=1;
  47   setsockopt(receive_fd,SOL_SOCKET,SO_BROADCAST,&opt,sizeof(opt));
  48
  49   local_addr.sin_family=AF_INET;
  50   local_addr.sin_port=htons(atoi(argv[1]));
  51   local_addr.sin_addr.s_addr=htonl(INADDR_ANY);
  52   bind(receive_fd,(const struct sockaddr *)&local_addr,sizeof(local_addr));
  53
  54   memset(&target_addr,0,sizeof(target_addr));
  55   target_addr.sin_family=AF_INET;
  56   target_addr.sin_port=htons(atoi(argv[1]));
  57   target_addr.sin_addr.s_addr=inet_addr(argv[1]);
  58   target_addr_len=sizeof(target_addr);
  59
  60   receive_bytes=1;
  61   while(receive_bytes>0) {
  62         unsigned char buf[1000];
  63         receive_bytes=recvfrom(receive_fd,buf,sizeof(buf),0,(struct sockaddr *)&target_addr,&target_addr_len);
  64         write_bytes=write(1,buf,receive_bytes);
  65   }
  66
  67   close(receive_fd);
  68   printf("connection closed ...\n");
  69   printf("%d from %d total bytes written.\n",write_bytes,receive_bytes);
  70
  71   return 0;
  72 }