getaddrinfo: properly implement AI_ADDRCONFIG

* Exclude the localhost interface when building the supported family list,
* Filter DNS replies to keep only the allowed address families.

Fixes #8293, for real this time.

src/kits/network/netresolv/irs/getaddrinfo.c

@@ -594,11 +594,22 @@ getaddrinfo(const char *hostname, const char *servname,
 		if (pai->ai_protocol == ANY && ex->e_protocol != ANY)
 			pai->ai_protocol = ex->e_protocol;
 
+		/* append entries to list of replies */
 		error = explore_fqdn(pai, hostname, servname, &cur->ai_next,
 		    &svd);
 
-		while (cur && cur->ai_next)
-			cur = cur->ai_next;
+		while (cur && cur->ai_next) {
+			if ((((uint64_t)1 << cur->ai_next->ai_family) & mask) == 0) {
+				/* entry does not match addrconfig mask, remove from list */
+				struct addrinfo* removed = cur->ai_next;
+				cur->ai_next = removed->ai_next;
+				removed->ai_next = NULL;
+				freeaddrinfo(removed);
+			} else {
+				/* entry does match, keep it in list and move to next one */
+				cur = cur->ai_next;
+			}
+		}
 	}
 
 	/* XXX */
@@ -1094,7 +1105,8 @@ addrconfig(uint64_t *mask)
 
 	*mask = 0;
 	for (ifa = ifaddrs; ifa != NULL; ifa = ifa->ifa_next)
-		if (ifa->ifa_addr && (ifa->ifa_flags & IFF_UP)) {
+		if (ifa->ifa_addr && (ifa->ifa_flags & IFF_UP)
+				&& !(ifa->ifa_flags & IFF_LOOPBACK)) {
 			assert(ifa->ifa_addr->sa_family < 64);
 			*mask |= (uint64_t)1 << ifa->ifa_addr->sa_family;
 		}