core: Don't log errors when dns find no more records

If the proxy is listeneing on both ipv4 and ipv6, DNS attempts are done for
both A and AAAA records. If the last of these lookup fails with no records
found, don't log an error if the first lookup did already return records.

dns_cache.c

@@ -3022,7 +3022,7 @@ inline static int dns_ip_resolve(	struct dns_hash_entry** e,
 									struct ip_addr* ip,
 									int flags)
 {
-	int ret;
+	int ret, orig_ret;
 	str host;
 	struct dns_hash_entry* orig;
 
@@ -3050,10 +3050,13 @@ inline static int dns_ip_resolve(	struct dns_hash_entry** e,
 		if (ret>=0) return ret;
 		if (!(flags&(DNS_IPV6_ONLY|DNS_IPV6_FIRST|DNS_IPV4_ONLY))){
 			/* not found, try with AAAA */
+			orig_ret=ret;
 			orig=*e;
 			*e=0;
 			*rr_no=0;
 			ret=dns_aaaa_resolve(e, rr_no, &host, ip);
+			if (ret==-E_DNS_NO_IP && orig_ret==-E_DNS_EOR)
+				ret=orig_ret;
 			/* delay original record release until we're finished with host*/
 			dns_hash_put(orig);
 		}
@@ -3067,10 +3070,13 @@ inline static int dns_ip_resolve(	struct dns_hash_entry** e,
 		if (ret>=0) return ret;
 		if ((flags&DNS_IPV6_FIRST) && !(flags&DNS_IPV6_ONLY)){
 			/* not found, try with A */
+			orig_ret=ret;
 			orig=*e;
 			*e=0;
 			*rr_no=0;
 			ret=dns_a_resolve(e, rr_no, &host, ip);
+			if (ret==-E_DNS_NO_IP && orig_ret==-E_DNS_EOR)
+				ret=orig_ret;
 			/* delay original record release until we're finished with host*/
 			dns_hash_put(orig);
 		}