Subject: SIOCGIFCONF wierdness
To: None <>
From: Alex Barclay <>
List: tech-net
Date: 05/08/2001 14:59:44
Hi all

I'm having trouble accessing the list of interfaces on the machine which
is a NetBSD-current/i386 (Kernel is a 1.5U)

I create a socket of type PF_INET, SOCK_DGRAM
try to use either SIOCGIFCONF or OSIOCGIFCONF and get very strange
results. Using SIOCGIFCONF I get a few of the interface names but by no
means all of them. Using OSIOCGIFCONF I get the interface names but no
address information.

Where did I go wrong??



int main()
        ifconf ifc;
        ifc.ifc_len = sizeof(ifreq)*100;
        ifc.ifc_ifcu.ifcu_buf = (caddr_t)malloc(sizeof(ifreq)*100);

        int sock = socket(PF_INET, SOCK_DGRAM, 0);
        int ret;
        ret = ioctl(sock, OSIOCGIFCONF, &ifc);
        if (ret != 0) {
                cerr << "ioctl - ret = " << ret << endl;
        cout << ifc.ifc_len/sizeof(ifreq) << endl;

        ifreq* ifr = ifc.ifc_ifcu.ifcu_req;
        for(int i = 0; i < ifc.ifc_len/sizeof(ifreq); ++i) {
                cout << ifr[i].ifr_name << endl;
        return 0;