[Mimedefang] SpamAssassin DnsResolver.pm problem with Embedded Interpreter

[David Eisner]

David Eisner wrote:
> When I turn on the embed flag, I have two problems.
>
> 1. mimedefang-multiplexor[24534]: WARNING: Something in your Perl 
> filter appears to have opened a file descriptor outside of any 
> function....
>
> 2.  mimedefang-multiplexor[24534]: Slave 0 stderr: dns: sendto() 
> failed:  at 
> /usr/lib/perl5/site_perl/5.8.0/Mail/SpamAssassin/DnsResolver.pm line 320.
> mimedefang-multiplexor[24534]: Slave 0 stderr: dns: select failed: Bad 
> file descriptor at 
> /usr/lib/perl5/site_perl/5.8.0/Mail/SpamAssassin/DnsResolver.pm line 347.
> last message repeated 8451 times


In case anybody cares, I solved the problem.

Summary:   Comment out the following from mimedefang-filter:

  # The next lines force SpamAssassin modules to be loaded and rules
  # to be compiled immediately.  This may improve performance on busy
  # mail servers.  Comment the lines out if you don't like them.
  if ($Features{"SpamAssassin"}) {
      spam_assassin_init()->compile_now(1) if defined(spam_assassin_init());


Longer explanation:

When mimedefang-multiplexor runs in embedded mode, mimedefang.pl sources 
mimedefang-filter before starting any slaves (this is documented).  The 
example mimedefang-filter calls spam_assassin_init() (which is in 
mimedefang.pl).  This, in turn, allocates $SASpamTester, the 
Mail::SpamAssassin object.  The Mail::SpamAssassin constructor allocates 
a resolver:

    $self->{resolver} = Mail::SpamAssassin::DnsResolver->new($self);

The problem is that the DnsResolver constructor calls connect_sock, 
which opens a socket "to the first nameserver listed /etc/resolv.conf".  
This produces error number 1.  Later, when the slaves are activated, 
this file descriptor gets closed, resulting in error 2.

Maybe a comment in mimedefang-filter should be added, something like:

  # The next lines force SpamAssassin modules to be loaded and rules
  # to be compiled immediately.  This may improve performance on busy
  # mail servers.  However,  it may cause problems when using an embedded
  # perl interpreter with some versions of  SpamAssassin. Comment the lines
  # out if you don't like them. 

-David