Re: [Exim] failed to find host name from IP address

Top Page
Delete this message
Reply to this message
Author: Jochen Erwied
Date:  
To: Exim Mailinglist
Subject: Re: [Exim] failed to find host name from IP address
Friday, May 03, 2002, 12:51:25 PM, you wrote:

> On Fri, 3 May 2002, Stanier, Alan M wrote:


> > 2002-05-03 11:06:22 recipients from [64.156.187.126] refused
> > (failed to find host name from IP address)


The reason is shown - DNS failure.

> conduct a manual test (-bh), that might reveal more information.


After exim died on an incoming connection, I did some tracking
revealing a bug for non-resolvable IP-addresses:

When host_name_lookup() gets a TRY_AGAIN, host_lookup_failed is not
changed (and sender_host_name is not filled). This happens twice, but
if even the second call to host_name_lookup() fails with TRY_AGAIN,
strcmpic() is called with a NULL-pointer (sender_host_name).

A quick patch for this is (not officical, of course):

--- ../exim-4.04.orig/src/smtp_in.c     Thu Apr 18 10:08:34 2002
+++ src/smtp_in.c       Fri May  3 13:25:18 2002
@@ -1878,5 +1878,8 @@
           if (!host_lookup_failed)
             {
-            helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
+            if(sender_host_name != NULL)
+              helo_verified = strcmpic(sender_host_name, sender_helo_name) == 0;
+            else
+              helo_verified = FALSE;


             if (helo_verified)
--
mbs GmbH      | http://www.mbs-software.de
Jochen Erwied | mailto:Jochen.Erwied@mbs-software.de
Roemerstr. 15 | phone: +49-2151-7294-0
47809 Krefeld | fax:   +49-2151-7294-50