-/* $Cambridge: exim/src/src/dns.c,v 1.15 2006/11/07 14:13:19 ph10 Exp $ */
+/* $Cambridge: exim/src/src/dns.c,v 1.18 2009/06/10 07:34:04 tom Exp $ */
/*************************************************
* Exim - an Internet mail transport agent *
*************************************************/
-/* Copyright (c) University of Cambridge 1995 - 2006 */
+/* Copyright (c) University of Cambridge 1995 - 2007 */
/* See the file NOTICE for conditions of use and distribution. */
/* Functions for interfacing with the DNS. */
Returns: DNS_SUCCEED successful lookup
DNS_NOMATCH name not found (NXDOMAIN)
or name contains illegal characters (if checking)
+ or name is an IP address (for IP address lookup)
DNS_NODATA domain exists, but no data for this type (NODATA)
DNS_AGAIN soft failure, try again later
DNS_FAIL DNS failure
number of bytes the message would need, so we need to check for this case. The
effect is to truncate overlong data.
-If we are running in the test harness, instead of calling the normal resolver
+On some systems, res_search() will recognize "A-for-A" queries and return
+the IP address instead of returning -1 with h_error=HOST_NOT_FOUND. Some
+nameservers are also believed to do this. It is, of course, contrary to the
+specification of the DNS, so we lock it out. */
+
+if ((
+ #ifdef SUPPORT_A6
+ type == T_A6 ||
+ #endif
+ type == T_A || type == T_AAAA) &&
+ string_is_ip_address(name, NULL) != 0)
+ return DNS_NOMATCH;
+
+/* If we are running in the test harness, instead of calling the normal resolver
(res_search), we call fakens_search(), which recognizes certain special
domains, and interfaces to a fake nameserver for certain special zones. */
else
dnsa->answerlen = res_search(CS name, C_IN, type, dnsa->answer, MAXPACKET);
-if (dnsa->answerlen > MAXPACKET) dnsa->answerlen = MAXPACKET;
+if (dnsa->answerlen > MAXPACKET)
+ {
+ DEBUG(D_dns) debug_printf("DNS lookup of %s (%s) resulted in overlong packet (size %d), truncating to %d.\n",
+ name, dns_text_type(type), dnsa->answerlen, MAXPACKET);
+ dnsa->answerlen = MAXPACKET;
+ }
if (dnsa->answerlen < 0) switch (h_errno)
{