Also add Gossip headers to resent group messages

[missytake]

• Operating System (Linux/Mac/Windows/iOS/Android): Linux
• Delta Chat Version: 1.40.4

Expected behavior

If I get added to a group through a resent message (which is properly encrypted), I can reply to it.

Actual behavior

My reply is not sent out, because I don't have the public keys of all group members.

Steps to reproduce the problem

1. [email protected] sends a message to [email protected]
2. [email protected] creates a group with [email protected] and [email protected] and sends a message
   - this message is unencrypted because bob doesn't have asdf's key, and it can't be delivered to [email protected], because c1.testrun.org prevents unencrypted messages to systemli.org
3. [email protected] writes a message to [email protected]
4. [email protected] re-sends the group creation message to [email protected]
   - this message is now displayed to bob as encrypted, even though it was sent unencrypted initially (to alice)
5. [email protected] tries to quote-reply to the group creation message
   - it can't be encrypted because [email protected] doesn't have [email protected]'s key, as the resent group creation message didn't have gossip headers
   - it can't be sent out as quote replies to encrypted messages always have to be encrypted

Screenshots

bob's view of the group creation message, after it was resent to [email protected] (note that it suddenly is shown as encrypted, even though it was sent to alice unencrypted)

asdf's view of the failed outgoing message from step 5

alice's view of the group creation message as she received it

Decrypted plaintext of bob's resent group creation message, as it arrived at asdf (note that the Autocrypt-Gossip headers are missing):

gpg: encrypted with ECDH key, ID 433C5A79284BD372
gpg: encrypted with ECDH key, ID F919D5690759780F
gpg: encrypted with 2048-bit RSA key, ID 17893D443E5A660B, created 2019-08-15
      "<[email protected]>"
Content-Type: text/plain; charset=utf-8; format=flowed; delsp=no;
	protected-headers="v1";
Subject: grouptry
Chat-Disposition-Notification-To: [email protected]
Chat-Group-ID: OB52UY7PwM0
Chat-Group-Name: =?utf-8?q?grouptry?=
From: <[email protected]>

Who receives this?
gpg: Signature made So 15 Okt 2023 14:03:27 CEST
gpg:                using EDDSA key 1A2277293043413A91715AE4CDC8AF7EBCCBB371
gpg: Can't check signature: No public key

Suggested Solution

Right now, resent messages don't contain Autocrypt-Gossip headers. I suggest to add them.