fix getnameinfo sockaddr size for IPv4

pass sizeof(struct sockaddr_in) for AF_INET instead of always using
sizeof(struct sockaddr_in6). also skip getnameinfo entirely for
non-matching interfaces rather than calling it for every entry.

1 files changed, 11 insertions, 9 deletions

diff --git a/components/ip.c b/components/ip.c
index 2cdad46..ac75661 100644
--- a/components/ip.c
+++ b/components/ip.c
@@ -30,18 +30,20 @@ ip(const char *interface, unsigned short sa_family)
 	for (ifa = ifaddr; ifa != NULL; ifa = ifa->ifa_next) {
 		if (!ifa->ifa_addr)
 			continue;
+		if (strcmp(ifa->ifa_name, interface) ||
+		    ifa->ifa_addr->sa_family != sa_family)
+			continue;
 
-		s = getnameinfo(ifa->ifa_addr, sizeof(struct sockaddr_in6),
+		s = getnameinfo(ifa->ifa_addr,
+		                (sa_family == AF_INET) ? sizeof(struct sockaddr_in)
+		                                       : sizeof(struct sockaddr_in6),
 		                host, NI_MAXHOST, NULL, 0, NI_NUMERICHOST);
-		if (!strcmp(ifa->ifa_name, interface) &&
-		    (ifa->ifa_addr->sa_family == sa_family)) {
-			freeifaddrs(ifaddr);
-			if (s != 0) {
-				warn("getnameinfo: %s", gai_strerror(s));
-				return NULL;
-			}
-			return bprintf("%s", host);
+		freeifaddrs(ifaddr);
+		if (s != 0) {
+			warn("getnameinfo: %s", gai_strerror(s));
+			return NULL;
 		}
+		return bprintf("%s", host);
 	}
 
 	freeifaddrs(ifaddr);