Empty output on SMIME signed email

[dlouzan]

Hello, we are working on an MR to add SMIME signing support to gitlab-ce, and we just noticed that rendering of the signed messages doesn't work, we get blank output (attached screenshots). This might be somehow expected since the component doesn't mention any SMIME support.

I'm not sure if this is an issue directly here, or the underlying letter_opener engine (or even maybe directly on rails / gitlab). Since gitlab is not giving me much log info, I'm not sure where to tackle this.

Any guidance is welcome. Thanks!

[dlouzan]

/cc @bufferoverflow

[fgrehm]

Hey!

Sorry for the long delay here. Did you figure this one out? If not, mind creating a minimal app that reproduces the problem? I might be able to take a look. Cheers!

[dlouzan]

Hey @fgrehm thanks for the answer. We implemented the support for S/MIME in Gitlab, though without previews 😅

I actually can provide you a fixture signed email that you can load with the Mail gem and use for your tests, just uploaded one in another MR under https://gitlab.com/gitlab-org/gitlab/-/blob/886e0213ab941ced894dc5de178468094111a5f9/spec/fixtures/emails/valid_reply_signed_smime.eml:

pry(main)> email = Mail.new(File.binread('./spec/fixtures/emails/valid_reply_signed_smime.eml'))
=> #<Mail::Message:70331044711260, Multipart: true, Headers: <Date: Mon, 17 Feb 2020 22:56:47 +0100>, <From: "Louzan Martinez, Diego (ext) (SI BP R&D ZG)" <diego.louzan.ext@siemens.com>>, <To: Administrator / htmltest <dlouzan.dummy+c034670b1623e617e15a3df64223d363@gmail.com>>, <Message-ID: <012E37D9-2A3F-4AC8-B79A-871F42914D86@siemens.com>>, <In-Reply-To: <note_1797@169.254.169.254>>, <References: <reply-c034670b1623e617e15a3df64223d363@169.254.169.254> <issue_451@169.254.169.254> <note_1797@169.254.169.254>>, <Subject: Re: htmltest | test issue (#1)>, <Mime-Version: 1.0>, <Content-Type: multipart/signed; protocol="application/pkcs7-signature";  micalg=sha256;  boundary="B_3664825007_1904734766">, <User-Agent: Microsoft-MacOutlook/10.22.0.200209>, <Thread-Topic: htmltest | test issue (#1)>>

pry(main)> email.multipart?
=> true

pry(main)> email.parts.map(&:content_type)
=> ["multipart/mixed; boundary=B_3664825007_384940722", "application/pkcs7-signature; name=smime.p7s"]

pry(main)> email.parts[0].part.map(&:content_type)
=> ["multipart/alternative; boundary=B_3664825007_1519466360",
 "image/png; name=gitlab_logo.png; x-mac-creator=4F50494D; x-mac-type=504E4766",

pry(main)> email.parts[0].parts[0].parts.map(&:content_type)
=> ["text/plain; charset=UTF-8", "text/html; charset=UTF-8"]

[fgrehm]

Hey @dlouzan! Sorry for the long delay here. Unfortunately I'm not sure how to make that .eml be translated into what letter_opener generates.

I'm not sure if this is an issue directly here, or the underlying letter_opener engine (or even maybe directly on rails / gitlab). Since gitlab is not giving me much log info, I'm not sure where to tackle this.

I guess I didn't pay enough attention to your msg in the first place (sorry about that!) but the rendered email we see on the right side of that screen is really just the .html generated by letter_opener (usually found under tmp/letter_opener). If the HTML is coming back blank I guess there's nothing much we can do on this project :-(

Would you mind opening an issue with letter_opener? Happy to help once we have an example application to try things out. For now will just close this issue but we can continue the discussion if you want to bounce some ideas before opening that issue :-)

Cheers!