udp_rcv.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 #define MAX_BUF 1472
  30
  31 int main(int argc, char *argv[]) {
  32   int receive_fd;
  33   int opt;
  34   struct sockaddr_in local_addr,target_addr;
  35   int receive_bytes, write_bytes;
  36   socklen_t target_addr_len;
  37   unsigned char buf[MAX_BUF];
  38
  39   if(argc!=2) {
  40     printf("usage: %s <port>\n",argv[0]);
  41     exit(1);
  42   }
  43
  44   if((receive_fd=socket(AF_INET,SOCK_DGRAM,0)) == -1) {
  45     printf("can't open socket.\n");
  46     exit(1);
  47   }
  48
  49   opt=1;
  50   setsockopt(receive_fd,SOL_SOCKET,SO_BROADCAST,&opt,sizeof(opt));
  51
  52   local_addr.sin_family=AF_INET;
  53   local_addr.sin_port=htons(atoi(argv[1]));
  54   local_addr.sin_addr.s_addr=htonl(INADDR_ANY);
  55   bind(receive_fd,(const struct sockaddr *)&local_addr,sizeof(local_addr));
  56
  57   memset(&target_addr,0,sizeof(target_addr));
  58  /*
  59   target_addr.sin_family=AF_INET;
  60   target_addr.sin_port=htons(atoi(argv[1]));
  61   target_addr.sin_addr.s_addr=inet_addr(argv[1]);
  62   target_addr_len=sizeof(target_addr);
  63  */
  64
  65   receive_bytes=1;
  66   while(receive_bytes>0) {
  67         receive_bytes=recvfrom(receive_fd,buf,sizeof(buf),0,(struct sockaddr *)&target_addr,&target_addr_len);
  68         write_bytes=write(1,buf,receive_bytes);
  69   }
  70
  71   close(receive_fd);
  72   printf("connection closed ...\n");
  73   printf("%d from %d total bytes written.\n",write_bytes,receive_bytes);
  74
  75   return 0;
  76 }