Rspamd: [New Feature] ARC support

[mpizzoli]

Classification (Please choose one option):

• [ ] Crash/Hang/Data loss
• [ ] WebUI/Usability
• [ ] Serious bug
• [ ] Other bug
• [x] Feature
• [ ] Enhancement

Reproducibility (Please choose one option):

• [ ] Always
• [ ] Sometimes
• [ ] Rarely
• [ ] Unable
• [ ] I didn’t try
• [X] Not applicable

Rspamd version:

1.5.x

Operation system, CPU, memory and environment:

N/A

Description (Please provide a descriptive summary of the issue):

There is a new email authentication mechanism called Authenticated Received Chain (ARC). It's purpose is to solve the authentication problem (SPF and/or DKIM failing) when an email is being forwarded.
It has born when "p=reject" policy within DMARC caused issues to the senders.
The main website related to this technology is http://arc-spec.org.

Compile errors (if any):

N/A

Steps to reproduce:

N/A

Expected results:

ARC headers inserted in the emails being processed.

Actual results:

N/A

Debugging information (see details here):

N/A

Configuration:

N/A

Additional information:

Gmail already implemented this: http://dmarc.ietf.narkive.com/yRPOYVTA/dmarc-ietf-implementation-update

[vstakhov]

Is there any available opensource implementation of this? In theory, I planned to add this support at some point, however, some points are not completely clear for me so far.

[mpizzoli]

Yes, there is. Or at least it should be...
https://github.com/mskucherawy/OpenARC

Honestly I don't have any more implementation-specific info about it.

Maybe here you can find any other useful info: http://arc-spec.org/?page_id=79

[vstakhov]

It is now implemented in the upcoming 1.6 release.