Initialize _res_ext.nsaddr_list alongside _res.nsaddr_list.

Fallback to initialization with 0 when _res.nsaddr_list is to small to hold an
IPv6 address.

OK bluhm@

1 files changed, 16 insertions, 9 deletions

diff --git a/lib/libc/asr/res_init.c b/lib/libc/asr/res_init.c
index f6cb36ad40a..01a3023bf87 100644
--- a/lib/libc/asr/res_init.c
+++ b/lib/libc/asr/res_init.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: res_init.c,v 1.8 2015/11/05 23:59:47 bluhm Exp $	*/
+/*	$OpenBSD: res_init.c,v 1.9 2016/03/23 18:45:03 chrisz Exp $	*/
 /*
  * Copyright (c) 2012 Eric Faurot <eric@openbsd.org>
  *
@@ -39,7 +39,7 @@ res_init(void)
 {
 	_THREAD_PRIVATE_MUTEX(init);
 	struct asr_ctx	*ac;
-	int i, j;
+	int i;
 
 	ac = _asr_use_resolver(NULL);
 
@@ -57,15 +57,22 @@ res_init(void)
 		if (_res.lookups[0] == '\0')
 			strlcpy(_res.lookups, ac->ac_db, sizeof(_res.lookups));
 
-		for (i = 0, j = 0; i < ac->ac_nscount && j < MAXNS; i++) {
-			if (ac->ac_ns[i]->sa_family != AF_INET ||
-			    ac->ac_ns[i]->sa_len > sizeof(_res.nsaddr_list[j]))
-				continue;
-			memcpy(&_res.nsaddr_list[j], ac->ac_ns[i],
+		for (i = 0; i < ac->ac_nscount && i < MAXNS; i++) {
+			/*
+			 * No need to check for length since we copy to a
+			 * struct sockaddr_storage with a size of 256 bytes
+			 * and sa_len has only 8 bits.
+			 */
+			memcpy(&_res_ext.nsaddr_list[i], ac->ac_ns[i],
 			    ac->ac_ns[i]->sa_len);
-			j++;
+			if (ac->ac_ns[i]->sa_len <= sizeof(_res.nsaddr_list[i]))
+				memcpy(&_res.nsaddr_list[i], ac->ac_ns[i],
+				    ac->ac_ns[i]->sa_len);
+			else
+				memset(&_res.nsaddr_list[i], 0,
+				    sizeof(_res.nsaddr_list[i]));
 		}
-		_res.nscount = j;
+		_res.nscount = i;
 		_res.options |= RES_INIT;
 	}
 	_THREAD_PRIVATE_MUTEX_UNLOCK(init);