IP addresses from a C program
#include <stdio.h>
#include <stropts.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <linux/netdevice.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <unistd.h>
int print_addresses(const int domain)
{
int s;
struct ifconf ifconf;
struct ifreq ifr[50];
int ifs;
int i;
s = socket(domain, SOCK_STREAM, 0);
if (s < 0) {
perror("socket");
return 0;
}
ifconf.ifc_buf = (char*) ifr;
ifconf.ifc_len = sizeof ifr;
if (ioctl(s, SIOCGIFCONF, &ifconf) == -1) {
perror("ioctl");
return 0;
}
ifs = ifconf.ifc_len / sizeof(ifr[0]);
printf("interfaces = %d:\n", ifs);
for (i = 0; i < ifs; i++) {
char ip[INET_ADDRSTRLEN];
struct sockaddr_in* s_in = (struct sockaddr_in*) &ifr[i].ifr_addr;
if (!inet_ntop(domain, &s_in->sin_addr, ip, sizeof(ip))) {
perror("inet_ntop");
return 0;
}
printf("%s - %s\n", ifr[i].ifr_name, ip);
}
close(s);
return 1;
}
int main(int argc, char* argv[])
{
int domains[] = { AF_INET, AF_INET6 };
int i;
for (i = 0; i < sizeof(domains) / sizeof(domains[0]); i++)
if (!print_addresses(domains[i])) {
return 1;
}
return 0;
}