dovecot - Apr 2019 - sieve match ANY header

I would like to create a sieve rule where I do a regex match on ALL 
headers, not a specific header.  I've been trying to find out the proper 
syntax, but haven't found anything.

Is this possible, and if so, how do I write it?

Thanks,
Shawn

On 8 Apr 2019, at 16:35, Shawn Heisey via dovecot <dovecot at dovecot.org>
wrote:
> I would like to create a sieve rule where I do a regex match on ALL
headers, not a specific header.
This is a really bad idea. Headers can be quite long, contain data that you do
not have control over, and checking all headers will be very expensive and may
leave you open to various regex attacks.

https://en.wikipedia.org/wiki/ReDoS

I don't know if it is possible, but I certainly wouldn't do it.


-- 
what was supposed to be so special about a full moon? It was only a big
circle of light. And the dark of the moon was only darkness. But
half-way between the two, when the moon was between the worlds of light
and dark, when even the moon lived on the edge... maybe then a witch
could believe in the moon. --Witches Abroad

On 4/8/2019 4:55 PM, @lbutlr via dovecot wrote:
> On 8 Apr 2019, at 16:35, Shawn Heisey via dovecot <dovecot at
dovecot.org> wrote:
>> I would like to create a sieve rule where I do a regex match on ALL
headers, not a specific header.
> 
> This is a really bad idea. Headers can be quite long, contain data that you
do not have control over, and checking all headers will be very expensive and
may leave you open to various regex attacks.
I want to catch any email where a specific IP address appears in any 
header.  I do not know what header it might appear in - that could vary 
widely depending on what email account is being used to send the message.

This will appear in exactly one sieve script (the one for my mailbox), 
and I will be in complete control of the regex used, so the regular 
expression denial of service is extremely unlikely.

I'm already potentially vulnerable to that because I have a handful of 
external users on my mail server and they can create whatever sieve 
scripts they want via the managesieve service.  Thankfully all of those 
people are pretty trustworthy folks.

Thanks,
Shawn