sendto-iface.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <net/if.h>

void  main(int argc,char** argv)
{
  struct ifreq ifr;
  int rc;

  if( argc != 4 )
  {
    printf( "Usage: %s iface ip port\n" , argv[0] );
    exit( EXIT_FAILURE );
  }
  
  int sd = socket(AF_INET, SOCK_DGRAM, 0);
  if( sd < 0 )
  { 
    perror( "Error in socket creation" );
    exit( EXIT_FAILURE );
  }

  memset(&ifr, 0, sizeof(ifr));
  strncpy( ifr.ifr_name, argv[1], sizeof(ifr.ifr_name) );

  if ((rc = setsockopt(sd, SOL_SOCKET, SO_BINDTODEVICE, (void *)&ifr, sizeof(ifr))) < 0)
  {   
      perror("Server-setsockopt() error for SO_BINDTODEVICE");
      close(sd);
      exit(EXIT_FAILURE);
  }

  struct sockaddr_in sin;
  memset(&sin, 0, sizeof(sin));
  sin.sin_family = AF_INET;
  if( inet_aton( argv[2], &sin.sin_addr ) == 0 )
  { 
    printf( "inet_aton: Invalid address: %s\n", argv[2] );
    close(sd);
    exit(EXIT_FAILURE);
  }
  sin.sin_port = htons(atoi(argv[3]));

  if( sendto( sd, "aaaa", 4, 0, (struct sockaddr*) &sin, sizeof(sin) ) < 0 )
  {   
      perror( "sendto()" );
      close(sd);
      exit(EXIT_FAILURE);
  }
  
  printf( "Enviado\n" );
  close( sd );
  exit( EXIT_SUCCESS );
}