iproute2: List interfaces without net address by default

This fixes regression in iproute2-3.5.1 when `ip addr show' skipped
interfaces without network layer address.

Wrong output:
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 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:50:54:00:0f:03 brd ff:ff:ff:ff:ff:ff
    inet 10.34.25.198/23 brd 10.34.25.255 scope global eth0
    inet6 2620:52:0:2219:250:54ff:fe00:f03/64 scope global dynamic
       valid_lft 2591919sec preferred_lft 604719sec
    inet6 fe80::250:54ff:fe00:f03/64 scope link
       valid_lft forever preferred_lft forever

Expected output:
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 127.0.0.1/8 scope host lo
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 00:50:54:00:0f:03 brd ff:ff:ff:ff:ff:ff
    inet 10.34.25.198/23 brd 10.34.25.255 scope global eth0
    inet6 2620:52:0:2219:250:54ff:fe00:f03/64 scope global dynamic
       valid_lft 2591896sec preferred_lft 604696sec
    inet6 fe80::250:54ff:fe00:f03/64 scope link
       valid_lft forever preferred_lft forever
5: veth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 8a:ec:35:34:1f:a8 brd ff:ff:ff:ff:ff:ff
6: veth0: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000
    link/ether 2e:97:ef:77:40:82 brd ff:ff:ff:ff:ff:ff
Signed-off-by: Petr Písař <ppisar@redhat.com>

ip/ipaddress.c

@@ -884,6 +884,7 @@ static void ipaddr_filter(struct nlmsg_chain *linfo, struct nlmsg_chain *ainfo)
 	lp = &linfo->head;
 	while ( (l = *lp) != NULL) {
 		int ok = 0;
+		int missing_net_address = 1;
 		struct ifinfomsg *ifi = NLMSG_DATA(&l->h);
 		struct nlmsg_list *a;
 
@@ -891,8 +892,10 @@ static void ipaddr_filter(struct nlmsg_chain *linfo, struct nlmsg_chain *ainfo)
 			struct nlmsghdr *n = &a->h;
 			struct ifaddrmsg *ifa = NLMSG_DATA(n);
 
-			if (ifa->ifa_index != ifi->ifi_index ||
-			    (filter.family && filter.family != ifa->ifa_family))
+			if (ifa->ifa_index != ifi->ifi_index)
+				continue;
+			missing_net_address = 0;
+			if (filter.family && filter.family != ifa->ifa_family)
 				continue;
 			if ((filter.scope^ifa->ifa_scope)&filter.scopemask)
 				continue;
@@ -927,6 +930,9 @@ static void ipaddr_filter(struct nlmsg_chain *linfo, struct nlmsg_chain *ainfo)
 			ok = 1;
 			break;
 		}
+		if (missing_net_address &&
+		    (filter.family == AF_UNSPEC || filter.family == AF_PACKET))
+			ok = 1;
 		if (!ok) {
 			*lp = l->next;
 			free(l);