[Mimedefang] Notifying virus recipients

[alan premselaar]

On 5/15/03 3:50 PM, "Adrian Chadd" <adrian at creative.net.au> wrote:

> 
> hi,
> 
> I've been playing with mimedefang and I have it nearly doing all the
> per-user options that I want.
> 
> The only thing I haven't managed to make it do yet is notify a recipient
> that they might have been sent a virus.
> 
> Ie, if foo at domain.com is sent a virus I've currently got it configured
> to send back to the virus sender a bounce message. I'd also like
> to email foo at domain.com that sender bar at domain2.com sent them a potential
> virus.
> 
> Any clues, example snippets?

check the mimedefang-filter man pages for action_replace_with_warning()
routines.  you'll have to pass it a message string to send to the recipient,
but that should do it.  if you look at the contrib/linuxorg/filter in the
rejected() subroutine, there's a good example of code to do this (even
though this particular code is for sending notifications that an executable
file was sent, not a virus)

> 
> Whilst I'm at embarrasing myself, take a look at:
> 
> (MAINTAINING STATE from mimedefang-filter manpage)
> 
> In general, for a given mail message, these groups of functions may be
> called in completely different Perl processes.   Thus,  there
> is no way to maintain state inside Perl between groups of functions.
> That is, you cannot set a variable in filter_relay and expect
> it to be available in filter_sender, because the filter_sender invocation
> might take place in a completely different process.
> 
> Now, in the example mimedefang-filter script the $FoundVirus variable
> is set in filter_begin() and tested in filter(). Thats keeping state, right?
> I'm doing some state-keeping magic in my filter for per-recipient
> filters and it _seems_ to Do the right thing. What gives?
> 
If i'm not mistaken, there were some changes made from previous versions of
MD (I forget specifically which, but I think it was from 2.29 to 2.30+) in
which *some* variables were able to maintain state.  Although David is a
better person to answer this.

Also, the way I interpret that statement is that, if a variable is set in
filter_sender or filter_relay, *THAT* particular variable will probably not
maintain state as those particular functions may not be called in any
specific order, and/or one or both of them may not be called at all
(depending on your configuration, and your filter). However, filter() and
filter_begin() should be called in the same order always.

If i'm not mistaken, the flow of the filter is:

via MILTER filter() gets called
then filter_begin() is called
then filter_relay(), filter_sender(), filter_recipient() and/or any other
necessary subroutines will be called depending on the requirements of the
mail being processed and the configuration.
lastly, filter_end() is called and returned via MILTER

(anyone, please feel to correct me if i'm wrong here)

hopefully this is helpful information (and hopefully accurate)

alan