Re: Qmail vs PowerDNS

Erwin Hoffmann <[email protected]> Tue, 25 Apr 2017 09:47:52 +0200
Newsgroups	gmane.mail.qmail.general
Message-ID	<[email protected]>
Hi all,


> Am 25.04.2017 um 06:47 schrieb Manvendra Bhangui <[email protected]>:
> 
> 
> On 25 April 2017 at 07:16, <[email protected]> wrote:
> Hi all.  I've been running qmail with great success for many years.
> I'm running gentoo with netqmail-1.06-r2; my network uses PowerDNS as
> its local DNS server.
> 
> I recently upgraded to pdns 4.  That's broken my qmail; now all
> attempts to send result in the dreaded
> 
> CNAME_lookup_failed_temporarily._(#4.4.3)
> 
> I've debugged a bit.  Netqmail-1.06-r2 includes the big-dns patch, and
> I verified that it was applied correctly.  I've run wireshark to
> capture the network transactions, and nothing looks amiss.  I'm
> getting valid responses, which are well under the 512-byte UDP limit
> (though that shouldn't matter).  The problem is clearly pdns, as when
> I change my resolver to some other server, qmail is perfectly happy.
> 
> What else should I look for?  What conditions other than oversize
> packets would cause qmail to consistently faile the CNAME lookup?
> 
> Thanks in advance...
> 
> I have done the following to fix the error. in qmail-remote.c,
> 
> change
> addrmangle(reciplist.sa + reciplist.len,*recips,&flagalias,!relayhost);
> to
> addrmangle(reciplist.sa + reciplist.len,*recips,&flagalias,0);

The prototyp of addrmangle looks the following:

void addrmangle(stralloc *saout,char *s,int *flagalias,int flagcname)  /* host has to be canonical, box has to be quoted */

Strange:

int flagcname <=> !relayhost

and later

*flagalias = flagcname

...

  if (flagcname)
    switch(dns_cname(&canonhost)) {
      case 0: *flagalias = 0; break;
      case DNS_MEM: temp_nomem();
      case DNS_SOFT: temp_dnscanon();
      case DNS_HARD: ; /* alias loop, not our problem */
    }

The entire routine seems to be questionable given today's conditions.

Regards.
--eh.





> 
> Look at
> https://lists.dns-oarc.net/pipermail/dns-operations/2013-January/009518.html

Dr. Erwin Hoffmann | FEHCom | http://www.fehcom.de | PGP Key-Id: EE00CF65
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