dying children?

Julian Field MailScanner at ecs.soton.ac.uk
Fri Aug 1 14:36:42 IST 2008

Drew Marshall wrote:
> On 1 Aug 2008, at 10:09, Julian Field wrote:
>> Richard Siddall wrote:
>>> Julian Field wrote:
>>>> Someone else showed me a message that suffered the same problem a 
>>>> few weeks ago. Unfortunately I don't think there's anything I can 
>>>> do about it, sorry. It's to do with nesting in the HTML analysis 
>>>> code. Once it gets too nested up, Perl segfaults.
>>>> Jules
>>> Jules,
>>> Does that mean it's something like an out-of-memory error in one of 
>>> the CPAN modules?  Can we fix it by getting the module author to 
>>> handle excessive nesting?
>> The most likely culprit is HTML::Parser, but I have direct evidence 
>> to back that. I just know that it's in the HTML parsing where it 
>> falls over. Does HTML::Parser contain any non-Perl code?
> Jules
> I seem to get a number of, what I think are, these types of mail that 
> choke MS and hold the child process up until it times out. Is there 
> any way that a mail that causes this sort of time out to be 
> automatically quarantined? Perhaps by changing the scan time out from 
> a batch time out to a message time out?
> The problem that I see is that if a batch has 10 messages in it (Often 
> mainly Spam) 1 of the messages chokes spam scanning, the whole batch 
> times out and lets the all the other spam messages through for delivery.
It's not a timeout issue. If it hits this, it brings the entire Perl 
system crashing down. Wrapping it in an eval and timeout may not help. 
It would certainly add more overhead.

I am open to all suggestions though!
> The benefit of quarantining is that:
> 1. I can find the dodgy message and perhaps we can find a solution to 
> a common problem
> 2. If it's spam the user won't care
> 3. Users will be notified as normal (E.g. through Mail Watch 
> notification or warning message etc depending on set up)
> 4. All other users still get their mail scanned
> While I can't code, I'm happy to test!
> Kind regards
> Drew
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Julian Field MEng CITP CEng
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