This change adds support for receiving
Autocrypt header in the protected part of encrypted message.
Autocrypt header is now also allowed in mailing lists.
Previously Autocrypt header was rejected when
List-Post header was present,
but the check for the address being equal to the From: address
is sufficient.
New experimental `protect_autocrypt` config is disabled
by default because Delta Chat with reception
support should be released first on all platforms.
close#2338
Concat error messages when receiving new ndns.
This PR adds a newline followed by the new NDN error to the error text.
Maybe we should use something more prominent like
```
-----------------------------------------------------------------------
```
or more newlines, but I'm not sure. This maybe has to be tested on a
real device to see what works best.
0a63083df7 (fix: Shorten message text in locally sent messages too)
sets `msgs.mime_modified` for long outgoing messages, but forgets to save full message text.
There are many reasons why we may fail to find valid signatures in a message, e.g. we don't yet know
a public key attached in the same message, anyway, if From is forged, the message must be rejected.
Also always take the displayname from encrypted From, even if no valid signatures are found.
If a display name should be protected (i.e. opportunistically encrypted), only put the corresponding
address to the unprotected headers. We protect the From display name only for verified chats,
otherwise this would be incompatible with Thunderbird and K-9 who don't use display names from the
encrypted part. Still, we always protect To display names as compatibility seems less critical here.
When receiving a messge, overwrite the From display name but not the whole From field as that would
allow From forgery. For the To field we don't really care. Anyway as soon as we receive a message
from the user, the display name will be corrected.
Co-authored-by: iequidoo <dgreshilov@gmail.com>
If multiple headers with the same name are present,
we must take the last one.
This is the one that is DKIM-signed if
this header is DKIM-signed at all.
Ideally servers should prevent adding
more From, To and Cc headers by oversigning
them, but unfortunately it is not common
and OpenDKIM in its default configuration
does not oversign any headers.
This protects Bob (the joiner) of sending unexpected-unencrypted messages during an otherwise nicely
running SecureJoin.
If things get stuck, however, we do not want to block communication -- the chat is just
opportunistic as usual, but that needs to be communicated:
1. If Bob's chat with Alice is `Unprotected` and a SecureJoin is started, then add info-message
"Establishing guaranteed end-to-end encryption, please wait..." and let `Chat::can_send()` return
`false`.
2. Once the info-message "Messages are guaranteed to be e2ee from now on" is added, let
`Chat::can_send()` return `true`.
3. If after SECUREJOIN_WAIT_TIMEOUT seconds `2.` did not happen, add another info-message "Could not
yet establish guaranteed end-to-end encryption but you may already send a message" and also let
`Chat::can_send()` return `true`.
Both `2.` and `3.` require the event `ChatModified` being sent out so that UI pick up the change wrt
`Chat::can_send()` (this is the same way how groups become updated wrt `can_send()` changes).
SECUREJOIN_WAIT_TIMEOUT should be 10-20 seconds so that we are reasonably sure that the app remains
active and receiving also on mobile devices. If the app is killed during this time then we may need
to do step 3 for any pending Bob-join chats (right now, Bob can only join one chat at a time).
`a.clone_from(&b)` is equivalent to `a = b.clone()` in functionality,
but can be overridden to reuse the resources of a to avoid unnecessary
allocations.
Let's add a 1-minute tolerance to `Params::MemberListTimestamp`.
This adds to the group membership consistency algo the following properties:
- If remote group membership changes were made by two members in parallel, both of them are applied,
no matter in which order the messages are received.
- If we remove a member locally, only explicit remote member additions/removals made in parallel are
allowed, but not the synchronisation of the member list from "To". Before, if somebody managed to
reply earlier than receiving our removal of a member, we added it back which doesn't look good.
If Subject is multiline-formatted, `mailparse` adds the leading whitespace to it. The solution is to
always remove the leading whitespace, because if Subject isn't multiline-formatted, it never
contains the leading whitespace anyway. But as for the trailing whitespace -- i checked -- it's
never removed, so let's keep this as is.
Before group avatar was sent as an attachment. Let's do the same as with user avatar and send group
avatar as base64. Receiver code uses the same functions for user and chat avatars, so base64 avatars
are supported for most receivers already.
Use sync messages for that as it is done for e.g. Config::Displayname. Maybe we need to remove
avatar synchronisation via usual messages then, but let's think of it a bit.
Currently when a user sets up another device by logging in, a new key is created. If a message is
sent from either device outside, it cannot be decrypted by the other device.
The message is replaced with square bracket error like this:
```
<string name="systemmsg_cannot_decrypt">This message cannot be decrypted.\n\n• It might already help to simply reply to this message and ask the sender to send the message again.\n\n• If you just re-installed Delta Chat then it is best if you re-setup Delta Chat now and choose "Add as second device" or import a backup.</string>
```
(taken from Android repo `res/values/strings.xml`)
If the message is outgoing, it does not help to "simply reply to this message". Instead, we should
add a translatable device message of a special type so UI can link to the FAQ entry about second
device. But let's limit such notifications to 1 per day. And as for the undecryptable message
itself, let it go to Trash if it can't be assigned to a chat by its references.
