Documentation and comment tidies.

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

diff --git a/src/src/dns.c b/src/src/dns.c
index 1a940b6abdd6818ec78554385a9b42dbccfad4f2..a6c6d053bcbb8087e698a6ddf178611d35dfb458 100644 (file)
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -1,4 +1,4 @@
-/* $Cambridge: exim/src/src/dns.c,v 1.14 2006/02/16 10:05:33 ph10 Exp $ */
+/* $Cambridge: exim/src/src/dns.c,v 1.16 2006/11/20 13:53:44 ph10 Exp $ */
 
 /*************************************************
 *     Exim - an Internet mail transport agent    *
@@ -453,6 +453,7 @@ 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
@@ -539,7 +540,20 @@ 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. */
 
@@ -677,12 +691,10 @@ 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)
       {
@@ -712,6 +724,8 @@ 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