dovecot - Feb 2017 - [Sieve] Is the way to run external script to get attachment?

Hello.

Read all about Extprograms, but have a question.
Use case:
Every day we have couple messages with attachment (from one sender, this 
is one-way communication). This attachment is uploads to ownCloud. By 
hand... need some automation.
As I see, pipe cat execute scripts with text data USER/FROM/SUBJECT - 
and I think with variables it can be any text data, how about attachment?

How I see this: script executes and as arg receives from sieve 
attachment file, or message file and we can parse it for attachment. 
When we have attachment - upload to ownCloud via RESTapi and purge message.

Found some realization for encrypt messages 
https://github.com/EtiennePerot/gpgit/blob/master/encmaildir.sh
but for me more easy just connect to IMAP and do what I want (but I love 
sieve).

Thanks.
<http://wiki.dovecot.org/Pigeonhole/Sieve/Plugins/Extprograms>

On Wed, 15 Feb 2017 17:13:31 +0700
Konstantin Shalygin <k0ste at k0ste.ru> wrote:
> Read all about Extprograms, but have a question.
> Use case:
> Every day we have couple messages with attachment (from one sender,
> this is one-way communication). This attachment is uploads to
> ownCloud. By hand... need some automation.
> As I see, pipe cat execute scripts with text data USER/FROM/SUBJECT - 
> and I think with variables it can be any text data, how about
> attachment?
> 
> How I see this: script executes and as arg receives from sieve 
> attachment file, or message file and we can parse it for attachment. 
> When we have attachment - upload to ownCloud via RESTapi and purge
> message.
> 
> Found some realization for encrypt messages 
> https://github.com/EtiennePerot/gpgit/blob/master/encmaildir.sh
> but for me more easy just connect to IMAP and do what I want (but I
> love sieve).
Do you really need Sieve for this?

IMO such things are best handled in the SMTP server:

1) Set up an alias for the mail address receiving these mails.

2) Make that alias expand both to its real final destination
   (an address, mails to which would be delivered to the IMAP
   folder as before) and to a special "program" entry which looks
   like "| /path/to/the/external/program".

See `man aliases` [4] for more info.

The program is supposed to receive the mail message to its standard
input stream and do whatever it wishes with them.  For instance, this
could be a shell script calling something like `ripmime` [1] on the
input, saving the attachments and then calling into whatever would
upload them.

Note that if the program completed its task OK, it should return with
the zero result code.  Otherwise it's advised to use one of result
codes defined by Sendmail, which are described in [2] and whose exact
numeric values could be googled (for instance, see [3]).  If your
program return a "known" exit code on error, you'll get better
diagnostics reported for that failure by your SMTP server.

1. http://www.pldaniels.com/ripmime/
2. http://docstore.mik.ua/orelly/networking/sendmail/ch36_05.htm
3. https://gist.github.com/bojanrajkovic/831993
4. http://www.postfix.org/aliases.5.html

Yes, I need Sieve for this, because actually I don't know sender or 
recipient.
Sieve script activate on some user in some time.

In fact, I did not read the specification 
*spec-bosch-sieve-extprograms.txt* on github (I use dovecot wiki old 
revisions) and generally was not attentive enough.

I wrote python script and this is works like a charm for month.

|require [ "vnd.dovecot.pipe", "variables" ]; if address :is
:all "from"
"k0ste at k0ste.ru" { pipe "sieve_to_owncloud"; } |

Incoming messages goes to script stdin, if script failed - messages 
delivered to mailbox, otherwise (script is ok) - message discarded.
On 02/16/2017 04:19 PM, Konstantin Khomoutov wrote:
> On Wed, 15 Feb 2017 17:13:31 +0700
> Konstantin Shalygin <k0ste at k0ste.ru> wrote:
>
>> Read all about Extprograms, but have a question.
>> Use case:
>> Every day we have couple messages with attachment (from one sender,
>> this is one-way communication). This attachment is uploads to
>> ownCloud. By hand... need some automation.
>> As I see, pipe cat execute scripts with text data USER/FROM/SUBJECT -
>> and I think with variables it can be any text data, how about
>> attachment?
>>
>> How I see this: script executes and as arg receives from sieve
>> attachment file, or message file and we can parse it for attachment.
>> When we have attachment - upload to ownCloud via RESTapi and purge
>> message.
>>
>> Found some realization for encrypt messages
>> https://github.com/EtiennePerot/gpgit/blob/master/encmaildir.sh
>> but for me more easy just connect to IMAP and do what I want (but I
>> love sieve).
> Do you really need Sieve for this?
>
> IMO such things are best handled in the SMTP server:
>
> 1) Set up an alias for the mail address receiving these mails.
>
> 2) Make that alias expand both to its real final destination
>     (an address, mails to which would be delivered to the IMAP
>     folder as before) and to a special "program" entry which
looks
>     like "| /path/to/the/external/program".
>
> See `man aliases` [4] for more info.
>
> The program is supposed to receive the mail message to its standard
> input stream and do whatever it wishes with them.  For instance, this
> could be a shell script calling something like `ripmime` [1] on the
> input, saving the attachments and then calling into whatever would
> upload them.
>
> Note that if the program completed its task OK, it should return with
> the zero result code.  Otherwise it's advised to use one of result
> codes defined by Sendmail, which are described in [2] and whose exact
> numeric values could be googled (for instance, see [3]).  If your
> program return a "known" exit code on error, you'll get
better
> diagnostics reported for that failure by your SMTP server.
>
> 1. http://www.pldaniels.com/ripmime/
> 2. http://docstore.mik.ua/orelly/networking/sendmail/ch36_05.htm
> 3. https://gist.github.com/bojanrajkovic/831993
> 4. http://www.postfix.org/aliases.5.html
-- 
Best regards,
Konstantin Shalygin