Added Tony's defer_foo patch to dnsdb lookups.

4 files changed, 69 insertions, 13 deletions

diff --git a/doc/doc-txt/ChangeLog b/doc/doc-txt/ChangeLog
index 6774dad4a..a12145aeb 100644
--- a/doc/doc-txt/ChangeLog
+++ b/doc/doc-txt/ChangeLog
@@ -1,4 +1,4 @@
-$Cambridge: exim/doc/doc-txt/ChangeLog,v 1.46 2004/12/20 14:57:05 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/ChangeLog,v 1.47 2004/12/20 15:24:27 ph10 Exp $
 
 Change log file for Exim from version 4.21
 -------------------------------------------
@@ -157,7 +157,8 @@ Exim version 4.50
         just the host names, not the priorities.
 
     (3) It is now possible to give a list of domains (or IP addresses) to be
-        looked up.
+        looked up. The behaviour when one of the lookups defers can be
+        controlled by a keyword.
 
     (4) It is now possible to specify the separator character for use when
         multiple records are returned.
diff --git a/doc/doc-txt/NewStuff b/doc/doc-txt/NewStuff
index 16c9c4653..3109ea96f 100644
--- a/doc/doc-txt/NewStuff
+++ b/doc/doc-txt/NewStuff
@@ -1,4 +1,4 @@
-$Cambridge: exim/doc/doc-txt/NewStuff,v 1.20 2004/12/17 14:52:44 ph10 Exp $
+$Cambridge: exim/doc/doc-txt/NewStuff,v 1.21 2004/12/20 15:24:27 ph10 Exp $
 
 New Features in Exim
 --------------------
@@ -152,9 +152,21 @@ Version 4.50
     single item are handled.
 
     The dnsdb lookup fails only if all the DNS lookups fail. If there is a
-    temporary DNS error for any of them, the remaining lookups are still done,
-    and only if none of them succeed does the dnsdb lookup defer. As long as at
-    least one of the DNS lookups yields some data, the dnsdb lookup succeeds.
+    temporary DNS error for any of them, the behaviour is controlled by
+    an optional keyword followed by a comma that may appear before the record
+    type. The possible keywords are "defer_strict", "defer_never", and
+    "defer_lax". With "strict" behaviour, any temporary DNS error causes the
+    whole lookup to defer. With "never" behaviour, a temporary DNS error is
+    ignored, and the behaviour is as if the DNS lookup failed to find anything.
+    With "lax" behaviour, all the queries are attempted, but a temporary DNS
+    error causes the whole lookup to defer only if none of the other lookups
+    succeed. The default is "lax", so the following lookups are equivalent:
+
+      ${lookup dnsdb{defer_lax,a=one.host.com:two.host.com}}
+      ${lookup dnsdb{a=one.host.com:two.host.com}}
+
+    Thus, in the default case, as long as at least one of the DNS lookups
+    yields some data, the dnsdb lookup succeeds.
 
 15. It is now possible to specify the character to be used as a separator when
     a dnsdb lookup returns data from more than one DNS record. The default is a
diff --git a/src/ACKNOWLEDGMENTS b/src/ACKNOWLEDGMENTS
index a914262c7..3c591fb9c 100644
--- a/src/ACKNOWLEDGMENTS
+++ b/src/ACKNOWLEDGMENTS
@@ -1,4 +1,4 @@
-$Cambridge: exim/src/ACKNOWLEDGMENTS,v 1.8 2004/12/20 14:57:05 ph10 Exp $
+$Cambridge: exim/src/ACKNOWLEDGMENTS,v 1.9 2004/12/20 15:24:28 ph10 Exp $
 
 EXIM ACKNOWLEDGEMENTS
 
@@ -123,6 +123,7 @@ Tony Finch                Expansion extensions
                             Patch for more daemon exiwhat information
                             Patch for -dd 
                             Patch for mxh lookup type in dnsdb 
+                            Patch for defer_foo in dndsb 
 Giuliano Gavazzi          Patches for OSX compilation
 Dominic Germain           Patch for exiqgrep MacOS X bug
 Oliver Gorwits            $load_average patch
diff --git a/src/src/lookups/dnsdb.c b/src/src/lookups/dnsdb.c
index 3f9dc8e78..9cd8612b1 100644
--- a/src/src/lookups/dnsdb.c
+++ b/src/src/lookups/dnsdb.c
@@ -1,4 +1,4 @@
-/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.5 2004/11/25 14:31:28 ph10 Exp $ */
+/* $Cambridge: exim/src/src/lookups/dnsdb.c,v 1.6 2004/12/20 15:24:28 ph10 Exp $ */
 
 /*************************************************
 *     Exim - an Internet mail transport agent    *
@@ -86,11 +86,17 @@ consist of a number of parts.
 separator character that is used when multiple records are found. The default 
 separator is newline.
 
-(b) If the next sequence of characters is a sequence of letters and digits 
+(b) If the next sequence of characters is 'defer_FOO' followed by a comma,
+the defer behaviour is set to FOO. The possible behaviours are: 'strict', where
+any defer causes the whole lookup to defer; 'lax', where a defer causes the
+whole lookup to defer only if none of the DNS queries succeeds; and 'never',
+where all defers are as if the lookup failed. The default is 'lax'.
+
+(c) If the next sequence of characters is a sequence of letters and digits 
 followed by '=', it is interpreted as the name of the DNS record type. The 
-default is "A".
+default is "TXT".
 
-(c) Then there follows list of domain names. This is a generalized Exim list, 
+(d) Then there follows list of domain names. This is a generalized Exim list, 
 which may start with '<' in order to set a specific separator. The default 
 separator, as always, is colon. */
 
@@ -102,6 +108,7 @@ int rc;
 int size = 256;
 int ptr = 0;
 int sep = 0;
+int defer_mode = PASS;
 int type = T_TXT;
 int failrc = FAIL;
 uschar *outsep = US"\n";
@@ -132,6 +139,40 @@ if (*keystring == '>')
   while (isspace(*keystring)) keystring++;
   } 
 
+/* Check for a defer behaviour keyword. */
+
+if (strncmpic(keystring, US"defer_", 6) == 0)
+  {
+  keystring += 6;
+  if (strncmpic(keystring, US"strict", 6) == 0)
+    {
+    defer_mode = DEFER;
+    keystring += 6;
+    }
+  else if (strncmpic(keystring, US"lax", 3) == 0)
+    {
+    defer_mode = PASS;
+    keystring += 3;
+    }
+  else if (strncmpic(keystring, US"never", 5) == 0)
+    {
+    defer_mode = OK;
+    keystring += 5;
+    }
+  else
+    {
+    *errmsg = US"unsupported dnsdb defer behaviour";
+    return DEFER;
+    }
+  while (isspace(*keystring)) keystring++;
+  if (*keystring++ != ',')
+    {
+    *errmsg = US"dnsdb defer behaviour syntax error";
+    return DEFER;
+    }
+  while (isspace(*keystring)) keystring++;
+  }
+
 /* If the keystring contains an = this must be preceded by a valid type name. */
 
 if ((equals = Ustrchr(keystring, '=')) != NULL)
@@ -214,8 +255,9 @@ while ((domain = string_nextinlist(&keystring, &sep, buffer, sizeof(buffer)))
   if (rc == DNS_NOMATCH || rc == DNS_NODATA) continue;
   if (rc != DNS_SUCCEED)
     {
-    failrc = DEFER;
-    continue;
+    if (defer_mode == DEFER) return DEFER;          /* always defer */
+      else if (defer_mode == PASS) failrc = DEFER;  /* defer only if all do */
+    continue;                                       /* treat defer as fail */
     }
   
   /* Search the returned records */