[Mimedefang] PING -> PONG support for mimedefang socket

[David F. Skoll]

Richard Laager wrote:

> What is PING/PONG support useful for?

I suppose periodic monitoring.  If you issue a PING and you
get a PONG, then you know that the multiplexor is working and
that the Perl slave responded.  Please be aware that with this
patch, if there are no free slaves, you will get an error instead
of a PONG.  So don't do anything drastic like restarting MIMEDefang
in that case.  Maybe if you get ten errors in a row, then you can assume
something is seriously wrong.

Regards,

David.