X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/a2042e783d5db744eeb94d4d6ac3bc86aef45511..5bfb4cdf352ad40304c6bbf0d826569dea761699:/src/src/dns.c

diff --git a/src/src/dns.c b/src/src/dns.c
index b86762ed4..c903d0ba9 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -1,10 +1,8 @@
-/* $Cambridge: exim/src/src/dns.c,v 1.15 2006/11/07 14:13:19 ph10 Exp $ */
-
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2006 */
+/* Copyright (c) University of Cambridge 1995 - 2009 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Functions for interfacing with the DNS. */
@@ -168,18 +166,42 @@ Returns:            nothing
 void
 dns_init(BOOL qualify_single, BOOL search_parents)
 {
-if ((_res.options & RES_INIT) == 0)
+res_state resp = os_get_dns_resolver_res();
+
+if ((resp->options & RES_INIT) == 0)
   {
-  DEBUG(D_resolver) _res.options |= RES_DEBUG;     /* For Cygwin */
+  DEBUG(D_resolver) resp->options |= RES_DEBUG;     /* For Cygwin */
+  os_put_dns_resolver_res(resp);
   res_init();
-  DEBUG(D_resolver) _res.options |= RES_DEBUG;
+  DEBUG(D_resolver) resp->options |= RES_DEBUG;
+  os_put_dns_resolver_res(resp);
   }
 
-_res.options &= ~(RES_DNSRCH | RES_DEFNAMES);
-_res.options |= (qualify_single? RES_DEFNAMES : 0) |
+resp->options &= ~(RES_DNSRCH | RES_DEFNAMES);
+resp->options |= (qualify_single? RES_DEFNAMES : 0) |
                 (search_parents? RES_DNSRCH : 0);
-if (dns_retrans > 0) _res.retrans = dns_retrans;
-if (dns_retry > 0) _res.retry = dns_retry;
+if (dns_retrans > 0) resp->retrans = dns_retrans;
+if (dns_retry > 0) resp->retry = dns_retry;
+
+#ifdef RES_USE_EDNS0
+if (dns_use_edns0 >= 0)
+  {
+  if (dns_use_edns0)
+    resp->options |= RES_USE_EDNS0;
+  else
+    resp->options &= ~RES_USE_EDNS0;
+  DEBUG(D_resolver)
+    debug_printf("Coerced resolver EDNS0 support %s.\n",
+        dns_use_edns0 ? "on" : "off");
+  }
+#else
+if (dns_use_edns0 >= 0)
+  DEBUG(D_resolver)
+    debug_printf("Unable to %sset EDNS0 without resolver support.\n",
+        dns_use_edns0 ? "" : "un");
+#endif
+
+os_put_dns_resolver_res(resp);
 }
 
 
@@ -424,9 +446,10 @@ Returns:     the return code
 static int
 dns_return(uschar *name, int type, int rc)
 {
+res_state resp = os_get_dns_resolver_res();
 tree_node *node = store_get_perm(sizeof(tree_node) + 290);
 sprintf(CS node->name, "%.255s-%s-%lx", name, dns_text_type(type),
-  _res.options);
+  resp->options);
 node->data.val = rc;
 (void)tree_insertnode(&tree_dns_fails, node);
 return rc;
@@ -453,6 +476,7 @@ Arguments:
 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
@@ -461,10 +485,11 @@ Returns:    DNS_SUCCEED   successful lookup
 int
 dns_basic_lookup(dns_answer *dnsa, uschar *name, int type)
 {
-int rc = -1;
 #ifndef STAND_ALONE
+int rc = -1;
 uschar *save;
 #endif
+res_state resp = os_get_dns_resolver_res();
 
 tree_node *previous;
 uschar node_name[290];
@@ -475,7 +500,7 @@ have many addresses in the same domain. We rely on the resolver and name server
 caching for successful lookups. */
 
 sprintf(CS node_name, "%.255s-%s-%lx", name, dns_text_type(type),
-  _res.options);
+  resp->options);
 previous = tree_search(tree_dns_fails, node_name);
 if (previous != NULL)
   {
@@ -504,7 +529,7 @@ For SRV records, we omit the initial _smtp._tcp. components at the start. */
 
 #ifndef STAND_ALONE   /* Omit this for stand-alone tests */
 
-if (check_dns_names_pattern[0] != 0 && type != T_PTR)
+if (check_dns_names_pattern[0] != 0 && type != T_PTR && type != T_TXT)
   {
   uschar *checkname = name;
   int ovector[3*(EXPAND_MAXN+1)];
@@ -539,7 +564,20 @@ if (check_dns_names_pattern[0] != 0 && type != T_PTR)
 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. */
 
@@ -548,7 +586,12 @@ if (running_in_test_harness)
 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)
   {