Re: [exim] Removing all headers with the same prefix
* Jeremy Harris on Tue, Apr 18, 2017 at 10:54:58PM +0100:
> It'll be a multistep process, probably. Treat ACLs as a programming
> language.
>
> […]
>
> But start with doing it as a sequence of
>
> set acl_m_foo =
I’m already doing something very similar to implement a home-grown
greylisting (with the heavy lifting coming from Postgres). This is
indeed one of the best ways I found out to build ACLs from scratch.
* Heiko Schlittermann via Exim-users on Wed, Apr 19, 2017 at 09:23:10AM +0200:
> As part of my data acl I use:
>
>warn set acl_m_headers_remove \
>= ${filter {MESSAGE_HEADERS}{match{$item}{\N^x-(?:ius|hh)-\N}}}
>
> to remember all headers matching /^x-(ius|hh)-/i in an ACL variable.
> The MESSAGE_HEADERS macro is:
>
> MESSAGE_HEADERS = \
> ${lc:${sg\
>{${map\
> { <\n ${sg {$message_headers_raw}{\N\n\s+\N}{ }} }\
> {${extract{1}{:}{$item}}}\
> }\
>}\
>{\N\n\N}\
>{:}\
>}}
Thanks for the pointer: This is exactly the direction I was looking for.
Now I know where to look, thanks!
Cheers,
Stefan
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Re: [exim] Removing all headers with the same prefix
Stefan Unterweger <28443.kr@8j1.enskribi.email> (Di 18 Apr 2017 20:07:33 CEST):
> I want to scrub certain kinds of headers for all incoming messages so
…
> I have tried to find some kind of string expansion which would give me a
> list of all message headers which start with my chosen prefix, or some
> other kind of trick to get similar results, but so far, I didn’t find
> anything. Of course I could list all possible combinations of ‘Spam-…’
> that I can think of, but this is kind of a losing battle…
As part of my data acl I use:
warn set acl_m_headers_remove \
= ${filter {MESSAGE_HEADERS}{match{$item}{\N^x-(?:ius|hh)-\N}}}
to remember all headers matching /^x-(ius|hh)-/i in an ACL variable.
The MESSAGE_HEADERS macro is:
MESSAGE_HEADERS = \
${lc:${sg\
{${map\
{ <\n ${sg {$message_headers_raw}{\N\n\s+\N}{ }} }\
{${extract{1}{:}{$item}}}\
}\
}\
{\N\n\N}\
{:}\
}}
The actual removal is done in the transport as follows:
begin transports
smtp:
driver = …
headers_remove = $acl_m_headers_remove
headers_add = $acl_m_headers_add
But, please note, this solution has not been reviewed for a long time, but
it is in use currently and seems to work.
Best regards from Dresden/Germany
Viele Grüße aus Dresden
Heiko Schlittermann
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Re: [exim] Removing all headers with the same prefix
On 2017-04-18, Stefan Unterweger <28443.kr@8j1.enskribi.email> wrote:
> Hi,
>
> I want to scrub certain kinds of headers for all incoming messages so
> that I can use them for myself—and trust them. In particular, I want to
> get rid of all headers which start with ‘Spam-’, no matter what comes
> after that prefix (be it ‘Spam-Score’, ‘Spam-Whitelisted’ or whatever my
> yet-to-be-designed antispam filters will come up with).
>
> The Exim Specification mentions in §43.25 that ‘wildcards are not
> permitted, nor is list expansion performed […] however, both connection
> and message variable expansions are performed.‘
>
> I have tried to find some kind of string expansion which would give me a
> list of all message headers which start with my chosen prefix, or some
> other kind of trick to get similar results, but so far, I didn’t find
> anything. Of course I could list all possible combinations of ‘Spam-…’
> that I can think of, but this is kind of a losing battle…
>
> Any ideas are appreciated.
something using ${sg perhaps.
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Re: [exim] Removing all headers with the same prefix
On 18/04/17 19:07, Stefan Unterweger wrote: > I want to scrub certain kinds of headers for all incoming messages so > that I can use them for myself—and trust them. In particular, I want to > get rid of all headers which start with ‘Spam-’, no matter what comes > after that prefix (be it ‘Spam-Score’, ‘Spam-Whitelisted’ or whatever my > yet-to-be-designed antispam filters will come up with). It'll be a multistep process, probably. Treat ACLs as a programming language. Start with all the headers. Treating them as a list, strip the content leaving just the header names. Filter for only the names you're interested in. Then feed that variable to headers_remove. You _might be able then, having constructed it sequentially, be able to compress it into a one-liner nested expansion - if you care. But start with doing it as a sequence of set acl_m_foo = operations, it's the only way to stay sane. -- Cheers, Jeremy -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
[exim] Removing all headers with the same prefix
Hi, I want to scrub certain kinds of headers for all incoming messages so that I can use them for myself—and trust them. In particular, I want to get rid of all headers which start with ‘Spam-’, no matter what comes after that prefix (be it ‘Spam-Score’, ‘Spam-Whitelisted’ or whatever my yet-to-be-designed antispam filters will come up with). The Exim Specification mentions in §43.25 that ‘wildcards are not permitted, nor is list expansion performed […] however, both connection and message variable expansions are performed.‘ I have tried to find some kind of string expansion which would give me a list of all message headers which start with my chosen prefix, or some other kind of trick to get similar results, but so far, I didn’t find anything. Of course I could list all possible combinations of ‘Spam-…’ that I can think of, but this is kind of a losing battle… Any ideas are appreciated. Cheers, Stefan -- ▪ Die Internetbleibe. Schick, magisch, leistungsstark. https://internetbleibe.de/ ▪ medoly media UG (haftungsbeschränkt) | Hausburgstraße 13, 10249 Berlin ▪ i...@medolymedia.de | https://medolymedia.de/ | Tel. 030 609 826‒560 | Fax …‒569 ▪ Geschäftsführer: Matthias Nothhaft | HRB 131198 (Amtsgericht Berlin-Charlottenburg), Sitz: Berlin, USt-ID: DE275221203 -- ## List details at https://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
