Added dns_use_edns0 main option.

[exim.git] / src / src / dns.c

diff --git a/src/src/dns.c b/src/src/dns.c
index b2a9c7ba4813d60c214c89a2c5369340301a013d..bfef69927649313d01bf45c234f8a7918aa61205 100644 (file)
--- 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    *
 *************************************************/
 
 
 /*************************************************
 *     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. */
 /* 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;
                 (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)
 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
             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
 dns_basic_lookup(dns_answer *dnsa, uschar *name, int type)
 {

-int rc = -1;

 #ifndef STAND_ALONE
 #ifndef STAND_ALONE

+int rc = -1;

 uschar *save;
 #endif
 
 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 */
 
 
 #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)];
   {
   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.
 
 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. */
 
 (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);
 
 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)
   {
 
 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;
     }
 
     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)
       {
     {
     if (cname_rr.data != NULL)
       {


@@ -692,15 +727,9 @@ for (i = 0; i < 10; i++)
       }
     else if (type_rr.data != NULL)
       {
       }
     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;
     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
   }       /* Loop back to do another lookup */
 
 /*Control reaches here after 10 times round the CNAME loop. Something isn't