retrieving network interface list

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# 1  
Old 03-07-2010
retrieving network interface list

I have a problem with retreiving network interface list using IOCTLs. I have 4 interfaces:
$ ip addr
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast state DOWN qlen 1000
    link/ether 00:1d:ba:39:f2:8d brd ff:ff:ff:ff:ff:ff
3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP qlen 1000
    link/ether 00:21:5c:0d:ad:15 brd ff:ff:ff:ff:ff:ff
    inet brd scope global wlan0
    inet6 fe80::221:5cff:fe0d:ad15/64 scope link
       valid_lft forever preferred_lft forever
4: pan0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN
    link/ether ae:97:70:65:ed:95 brd ff:ff:ff:ff:ff:ff

But in my program just the lo interface is found. Why can't I get all interfaces?
Here's the code:
struct interface {
	char			ifname[MAXINTFNAME_LEN];
	uint8_t			addr[MACADDR_LEN];
	int			if_index;
	struct sockaddr_in	if_broadaddr;

int get_interface_info(struct interface* interf)
	struct ifreq ifr;
	struct ifreq *ifr_arr;
	struct ifconf ifc;
	int found = 0;

	char buf[1024] = {'\0'};
	int s = 0, ret = 0, i = 0;

	if (!interf || interf->ifname==NULL)
		return -1;

	memset(&ifr, 0, sizeof ifr);
	memset(&ifc, 0, sizeof ifc);

	s = socket(AF_INET, SOCK_DGRAM, 0);
	if (s==-1) {
		return -1;

	ifc.ifc_len = sizeof(buf);
        ifc.ifc_buf = buf;
	ioctl(s, SIOCGIFCONF, &ifc);

	ifr_arr = ifc.ifc_req;
	for (i = ifc.ifc_len / sizeof(struct ifreq); --i >= 0; ifr_arr++) {
		if (!strcmp(ifr_arr->ifr_name, interf->ifname)) {
			strcpy(ifr.ifr_name, interf->ifname);
			if (0 == (ret=ioctl(s, SIOCGIFFLAGS, &ifr))) {
				if (0 == (ret=ioctl(s, SIOCGIFHWADDR, &ifr))) {
					memcpy(interf->addr, ifr.ifr_hwaddr.sa_data, MACADDR_LEN);
					if (0 ==(ret=ioctl(s, SIOCGIFINDEX, &ifr))) {
						interf->if_index = ifr.ifr_ifindex;
					if (0 == (ret=ioctl(s, SIOCGIFBRDADDR, &ifr))) {
						memset(&(interf->if_broadaddr), 0x0, sizeof(interf->if_broadaddr));
						memcpy(&(interf->if_broadaddr), (struct sockaddr_in*)(&(ifr.ifr_ifru.ifru_broadaddr)), sizeof(ifr.ifr_ifru.ifru_broadaddr));
			found = 1;
	if (!found)
		return -2;
	return ret;

My system is Linux 2.6.31
# 2  
Old 03-07-2010
Perhaps the break statement in your code has something to do with it.
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