getifaddrs.c

/// Based on https://bugzilla.redhat.com/show_bug.cgi?id=178986#c1

#include <sys/types.h>
#include <unistd.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <ifaddrs.h>
#include <errno.h>
#include <string.h>
#include <stdio.h>
#include <net/if.h>

void print_addr(const char *prefix, struct sockaddr *sa)
{
    char addr[128];

    if (!sa)
        return;

    printf("(%s)\t(%s) ", prefix, inet_ntop(
        sa->sa_family,
        sa->sa_family == AF_INET
            ? (void*)&(((struct sockaddr_in*)sa)->sin_addr)
            : (void*)&(((struct sockaddr_in6*)sa)->sin6_addr),
        &(addr[0]),
        128
    ));
}

int main(int argc, char **argv, char **envp)
{
    struct ifaddrs *ifa = NULL, *ifap = NULL;

    if ((getifaddrs( &ifap ) != 0) || (!ifap)) {
        fprintf(stderr,"getifaddrs failed: %s\n", strerror(errno));
        return 1;
    }

    for (ifa = ifap; ifa != 0L; ifa = ifa->ifa_next) {
        printf("%s\t(flags=%s)\t",
            ifa->ifa_name,
            ifa->ifa_flags & IFF_POINTOPOINT ? "IFF_POINTOPOINT" : "IFF_BROADCAST"
        );
        print_addr("ifa_addr", ifa->ifa_addr);
        print_addr("ifu_dstaddr", ifa->ifa_ifu.ifu_dstaddr);
        printf("\n");
    }

    return 0;
}