Dedupe incoming messages by timestamp

[michaelkirk]

Bug description

Occasionally, especially in a group setting, we'll see duplicated incoming messages. Usually this can be traced back to the sender repeatedly sending their message because of a previously perceived failure to send.

Steps to reproduce

I'm not exactly sure here, but I think it's like this:

• Start a group with Alice Android, Ivan iOS, and Wally Whatever.
• Alice sends a "hello" message to the group, which successfully sends to Ivan, but fails to send to Wally (for whatever reason. Maybe keychange?)
• Alice retries to send to Wally

Actual result: Ivan sees two "hello" messages from Alice. One for the original send attempt, and one for the retry.

Expected result: Ivan should only see one "hello" message. The second-received message should be silently discarded based on (sender, device, timestamp).

[2-4601]

You can reproduce this with signalapp/Signal-Android#2639
I.e. get in a bad coverage area, try sending group messages and when they fail hit those resend buttons.

I think the Android counterpart is this: signalapp/Signal-Android@7e51d61

[michaelkirk]

Will be in the next release

Solved by signalapp/SignalServiceKit#119