Do RE compilations at daemon startup. Bug 1568

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

diff --git a/src/src/dns.c b/src/src/dns.c
index c903d0ba9840e1fccddc88120611afac1c205db9..2968fba19dba2d7906d1e7ea1c96471347048eff 100644 (file)
--- a/src/src/dns.c
+++ b/src/src/dns.c
@@ -2,7 +2,7 @@
 *     Exim - an Internet mail transport agent    *
 *************************************************/
 
-/* Copyright (c) University of Cambridge 1995 - 2009 */
+/* Copyright (c) University of Cambridge 1995 - 2014 */
 /* See the file NOTICE for conditions of use and distribution. */
 
 /* Functions for interfacing with the DNS. */
@@ -159,12 +159,13 @@ the first time we have been here, and set the resolver options.
 Arguments:
   qualify_single    TRUE to set the RES_DEFNAMES option
   search_parents    TRUE to set the RES_DNSRCH option
+  use_dnssec        TRUE to set the RES_USE_DNSSEC option
 
 Returns:            nothing
 */
 
 void
-dns_init(BOOL qualify_single, BOOL search_parents)
+dns_init(BOOL qualify_single, BOOL search_parents, BOOL use_dnssec)
 {
 res_state resp = os_get_dns_resolver_res();
 
@@ -201,6 +202,41 @@ if (dns_use_edns0 >= 0)
         dns_use_edns0 ? "" : "un");
 #endif
 
+#ifndef DISABLE_DNSSEC
+# ifdef RES_USE_DNSSEC
+#  ifndef RES_USE_EDNS0
+#   error Have RES_USE_DNSSEC but not RES_USE_EDNS0?  Something hinky ...
+#  endif
+if (use_dnssec)
+  resp->options |= RES_USE_DNSSEC;
+if (dns_dnssec_ok >= 0)
+  {
+  if (dns_use_edns0 == 0 && dns_dnssec_ok != 0)
+    {
+    DEBUG(D_resolver)
+      debug_printf("CONFLICT: dns_use_edns0 forced false, dns_dnssec_ok forced true, ignoring latter!\n");
+    }
+  else
+    {
+    if (dns_dnssec_ok)
+      resp->options |= RES_USE_DNSSEC;
+    else
+      resp->options &= ~RES_USE_DNSSEC;
+    DEBUG(D_resolver) debug_printf("Coerced resolver DNSSEC support %s.\n",
+        dns_dnssec_ok ? "on" : "off");
+    }
+  }
+# else
+if (dns_dnssec_ok >= 0)
+  DEBUG(D_resolver)
+    debug_printf("Unable to %sset DNSSEC without resolver support.\n",
+        dns_dnssec_ok ? "" : "un");
+if (use_dnssec)
+  DEBUG(D_resolver)
+    debug_printf("Unable to set DNSSEC without resolver support.\n");
+# endif
+#endif /* DISABLE_DNSSEC */
+
 os_put_dns_resolver_res(resp);
 }
 
@@ -394,6 +430,42 @@ return &(dnss->srr);
 
 
 
+/*************************************************
+*    Return whether AD bit set in DNS result     *
+*************************************************/
+
+/* We do not perform DNSSEC work ourselves; if the administrator has installed
+a verifying resolver which sets AD as appropriate, though, we'll use that.
+(AD = Authentic Data)
+
+Argument:   pointer to dns answer block
+Returns:    bool indicating presence of AD bit
+*/
+
+BOOL
+dns_is_secure(dns_answer *dnsa)
+{
+#ifdef DISABLE_DNSSEC
+DEBUG(D_dns)
+  debug_printf("DNSSEC support disabled at build-time; dns_is_secure() false\n");
+return FALSE;
+#else
+HEADER *h = (HEADER *)dnsa->answer;
+return h->ad ? TRUE : FALSE;
+#endif
+}
+
+static void
+dns_set_insecure(dns_answer * dnsa)
+{
+HEADER * h = (HEADER *)dnsa->answer;
+h->ad = 0;
+}
+
+
+
+
+
 /*************************************************
 *            Turn DNS type into text             *
 *************************************************/
@@ -415,11 +487,13 @@ switch(t)
   case T_AAAA:  return US"AAAA";
   case T_A6:    return US"A6";
   case T_TXT:   return US"TXT";
+  case T_SPF:   return US"SPF";
   case T_PTR:   return US"PTR";
   case T_SOA:   return US"SOA";
   case T_SRV:   return US"SRV";
   case T_NS:    return US"NS";
   case T_CNAME: return US"CNAME";
+  case T_TLSA:  return US"TLSA";
   default:      return US"?";
   }
 }
@@ -534,14 +608,12 @@ if (check_dns_names_pattern[0] != 0 && type != T_PTR && type != T_TXT)
   uschar *checkname = name;
   int ovector[3*(EXPAND_MAXN+1)];
 
-  if (regex_check_dns_names == NULL)
-    regex_check_dns_names =
-      regex_must_compile(check_dns_names_pattern, FALSE, TRUE);
+  dns_pattern_init();
 
   /* For an SRV lookup, skip over the first two components (the service and
   protocol names, which both start with an underscore). */
 
-  if (type == T_SRV)
+  if (type == T_SRV || type == T_TLSA)
     {
     while (*checkname++ != '.');
     while (*checkname++ != '.');
@@ -686,7 +758,8 @@ int
 dns_lookup(dns_answer *dnsa, uschar *name, int type, uschar **fully_qualified_name)
 {
 int i;
-uschar *orig_name = name;
+const uschar *orig_name = name;
+BOOL secure_so_far = TRUE;
 
 /* Loop to follow CNAME chains so far, but no further... */
 
@@ -741,7 +814,12 @@ for (i = 0; i < 10; i++)
 
   /* If any data records of the correct type were found, we are done. */
 
-  if (type_rr.data != NULL) return DNS_SUCCEED;
+  if (type_rr.data != NULL)
+    {
+    if (!secure_so_far)        /* mark insecure if any element of CNAME chain was */
+      dns_set_insecure(dnsa);
+    return DNS_SUCCEED;
+    }
 
   /* If there are no data records, we need to re-scan the DNS using the
   domain given in the CNAME record, which should exist (otherwise we should
@@ -754,6 +832,9 @@ for (i = 0; i < 10; i++)
   if (datalen < 0) return DNS_FAIL;
   name = data;
 
+  if (!dns_is_secure(dnsa))
+    secure_so_far = FALSE;
+
   DEBUG(D_dns) debug_printf("CNAME found: change to %s\n", name);
   }       /* Loop back to do another lookup */
 
@@ -1189,4 +1270,16 @@ else
 return yield;
 }
 
+
+
+void
+dns_pattern_init(void)
+{
+if (check_dns_names_pattern[0] != 0 && !regex_check_dns_names)
+  regex_check_dns_names =
+    regex_must_compile(check_dns_names_pattern, FALSE, TRUE);
+}
+
+/* vi: aw ai sw=2
+*/
 /* End of dns.c */