Obtaining network device details using getifaddrs(3)

scandev.cpp

#include <stdio.h>
#include <stdint.h>
#include <ifaddrs.h>
#include <netdb.h>


int main(int argc, char** argv) {
    struct ifaddrs* addrs;
    struct ifaddrs* ifa;

    if (getifaddrs(&addrs) < 0) {
        perror("getifaddrs");
        return 1;
    }

    // For human-readable IP addresses
    char host[NI_MAXHOST];
    char hostDest[NI_MAXHOST];
    char netmask[NI_MAXHOST];

    for (ifa = addrs; ifa; ifa = ifa->ifa_next) {
        if (ifa->ifa_addr == NULL)
            continue;

        if (ifa->ifa_addr->sa_family != AF_INET)
            continue;


        // Extract human-readable IP addresses
        if (getnameinfo(ifa->ifa_addr, sizeof(struct sockaddr_in), host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST) < 0) {
            perror("getnameinfo");
            continue;
        }

        if (getnameinfo(ifa->ifa_dstaddr, sizeof(struct sockaddr_in), hostDest, NI_MAXHOST, NULL, 0, NI_NUMERICHOST) < 0) {
            perror("getnameinfo");
            continue;
        }

        if (getnameinfo(ifa->ifa_netmask, sizeof(struct sockaddr_in), netmask, NI_MAXHOST, NULL, 0, NI_NUMERICHOST) < 0) {
            perror("getnameinfo");
            continue;
        }


        // Display extracted info
        printf("Name: %16s\n", ifa->ifa_name);
        printf("Addr: %16s [%08llx]\n", host, ((struct sockaddr_in*)ifa->ifa_addr)->sin_addr);
        printf("Dest: %16s [%08llx]\n", hostDest, ((struct sockaddr_in*)ifa->ifa_dstaddr)->sin_addr);
        printf("Mask: %16s [%08llx]\n", netmask, ((struct sockaddr_in*)ifa->ifa_netmask)->sin_addr);
        printf("\n");
    }

    freeifaddrs(addrs);
    return 0;
}