int icmp_select_best_ip(char ip_list[][16], int ip_num, char *best_ip)
{
int sockfd = 0;
struct timeval time_delay, min_time;
struct sockaddr_in from_addr;
char *cur_ip = NULL, *best = NULL, ip_str[16] = {'\0'};
int ip_idx = 0;
if(!ip_list || !best_ip || ip_num <= 1)
return -1;
sockfd = icmp_socket();
if(sockfd < 0){
perror("socket error");
return sockfd;
}
min_time.tv_sec = 0x0FFFFFFF;
min_time.tv_usec = 0x0FFFFFFF;
while(1)
{
if(ip_idx >= ip_num)
break;
cur_ip = ip_list[ip_idx];
if(!cur_ip)
break;
select_best_ip(sockfd, cur_ip, &time_delay, &from_addr);
printf("%s %ld %ld \n", cur_ip, time_delay.tv_sec, time_delay.tv_usec);
if(tv_min(&time_delay, &min_time)){
memset(ip_str,0,sizeof(ip_str));
strncpy(ip_str, inet_ntoa(from_addr.sin_addr), strlen(inet_ntoa(from_addr.sin_addr)));
best = ip_str;
}
++ip_idx;
}
close(sockfd);
if(best)
strcpy(best_ip, best);
else
return -1;
return 0;
}
int main(int argc, char **argv)
{
char *prgName = NULL;
int c;
char *iface = NULL;
if ( (prgName=strrchr(argv[0],'/')) )
prgName++;
else
prgName = argv[0];
while( (c = getopt(argc, argv, "i:h")) > 0)
{
switch(c)
{
case 'i':
iface = optarg;
break;
case 'h':
usage(prgName);
return 1;
break;
}
}
if ( iface == NULL )
{
usage(prgName);
return 1;
}
/* open socket */
int fd = icmp_socket(iface);
if ( fd == -1 ) return 1;
/* send a router solicitation */
unsigned char buf[2048];
if ((c = send_ra_solicit(fd, buf))< 0 ) return 1;
/* listen for router advertisement */
struct pollfd pollfd;
pollfd.fd = fd;
pollfd.events = POLLIN;
pollfd.revents = 0;
int rp = poll(&pollfd, 1, 2000); /* wait max 2 sec. */
if ( rp > 0 )
{
/* print prefix on stdout */
char ans_data[4096];
struct iovec iov;
struct msghdr msg;
int cc;
iov.iov_len = sizeof(ans_data);
iov.iov_base = ans_data;
memset(&msg, 0, sizeof(msg));
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_iov = &iov;
msg.msg_iovlen = 1;
msg.msg_control = ans_data;
msg.msg_controllen = sizeof(ans_data);
cc = recvmsg(fd, &msg, MSG_DONTWAIT);
if (cc < 0)
{
perror("recvmsg:");
return 1;
}
else
{
parse_reply(&msg, cc);
}
}
else
{
return 1;
}
return 0;
}