[Mimedefang] MD, logging, and a little bit about the multiplexor

[David F. Skoll]

On Mon, 30 Sep 2002, Clayton, Nik [IT] wrote:

> Instead of using the Syslog module for logging, MD should use something
> with a bit more flexibility -- e.g., Log::Channel

Looks interesting.

> However, if you want to log information from within an MD filter, you're
> then left with whatever MD supplied for the logging identity, log options,
> and facility in the openlog() call.

You can change the facility in syslog, like this:

	syslog('local7|info', "blah blah blah...");

>    * There's no guarantee that future versions of MD will call openlog()
>      with the same parameters.

I hereby give such a guarantee. :-)

>    * There's no way to log within your filter with a different identity,
>      options, or facility, without first calling closelog(), then
>      openlog() with new options, then closelog() again, then openlog()
>      with the old options.  This is tricky:

Identity and options are fixed, but you can change facility.

>     use Log::Channel;
>     use Log::Dispatch::Syslog;

I'll look into this.  I'm hesitant to add yet more Perl module dependencies,
though.  Also, John Kirkland has contributed code to log messages in
a standardized format, suitable for scripts he has to generate graphs.
That may help alleviate the problem.

I think my preferred solution will be to make Log::Channel a run-time
detectable option (much like SpamAssassin) so if you have it, great, but
if you don't, you can still use MIMEDefang.

> in the previous example) it would be great if there was a filter_init()
> (or some such) that was guaranteed to be called exactly once, and at a
> defined point in the MD start up process.

Easily done; put this in your filter:

	sub filter_init {
		# whatever
	}

	# Right before the end
	filter_init();
	1;

The filter file is read with "do" exactly once; you can do initialization
by calling Perl code from outside any subroutine definition.

Regards,

David.