X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/433a298016c18052dae7554c6770013578e40be8..e97d1f088ab357d806bff8b7d5f3fce068a85989:/src/src/dns.c

diff --git a/src/src/dns.c b/src/src/dns.c
index b2a9c7ba4..bfef69927 100644
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -1,10 +1,10 @@
-/* $Cambridge: exim/src/src/dns.c,v 1.12 2005/10/04 08:54:33 ph10 Exp $ */
+/* $Cambridge: exim/src/src/dns.c,v 1.21 2009/11/16 19:50:36 nm4 Exp $ */
 
 /*************************************************
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2005 */
+/* Copyright (c) University of Cambridge 1995 - 2009 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Functions for interfacing with the DNS. */
@@ -180,6 +180,24 @@ _res.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;
+
+#ifdef RES_USE_EDNS0
+if (dns_use_edns0 >= 0)
+  {
+  if (dns_use_edns0)
+    _res.options |= RES_USE_EDNS0;
+  else
+    _res.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
 }
 
 
@@ -453,6 +471,7 @@ 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
@@ -461,8 +480,8 @@ 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
 
@@ -504,7 +523,7 @@ 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 +558,20 @@ 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 +580,12 @@ 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)
   {
@@ -677,12 +714,10 @@ for (i = 0; i < 10; i++)
     else if (rr->type == T_CNAME) cname_rr = *rr;
     }
 
-  /* If a CNAME was found, take the fully qualified name from it; otherwise
-  from the first data record, if present. For testing, there is a magic name
-  that gets its casing adjusted, because my resolver doesn't seem to pass back
-  upper case letters in domain names. */
+  /* For the first time round this loop, if a CNAME was found, take the fully
+  qualified name from it; otherwise from the first data record, if present. */
 
-  if (fully_qualified_name != NULL)
+  if (i == 0 && fully_qualified_name != NULL)
     {
     if (cname_rr.data != NULL)
       {
@@ -692,15 +727,9 @@ for (i = 0; i < 10; i++)
       }
     else if (type_rr.data != NULL)
       {
-      if (running_in_test_harness &&
-          Ustrcmp(type_rr.name, "uppercase.test.ex") == 0)
-        *fully_qualified_name = US"UpperCase.test.ex";
-      else
-        {
-        if (Ustrcmp(type_rr.name, *fully_qualified_name) != 0 &&
-            type_rr.name[0] != '*')
-          *fully_qualified_name = string_copy_dnsdomain(type_rr.name);
-        }
+      if (Ustrcmp(type_rr.name, *fully_qualified_name) != 0 &&
+          type_rr.name[0] != '*')
+        *fully_qualified_name = string_copy_dnsdomain(type_rr.name);
       }
     }
 
@@ -718,6 +747,8 @@ for (i = 0; i < 10; i++)
     cname_rr.data, (DN_EXPAND_ARG4_TYPE)data, 256);
   if (datalen < 0) return DNS_FAIL;
   name = data;
+
+  DEBUG(D_dns) debug_printf("CNAME found: change to %s\n", name);
   }       /* Loop back to do another lookup */
 
 /*Control reaches here after 10 times round the CNAME loop. Something isn't