Adding Key Update Before Every New GroupIntent

[lfzkoala]

trying to solve this issue - #347

This is what I'm doing

Follow the readme file (xmtp_mls/migrations) to create a migration for SQL database

Install the CLI onto local system (one-time)
cargo install diesel_cli --no-default-features --features sqlite

Create migration SQL
diesel migration generate key_update

Edit the up.sql and down.sql files created
Put in up.sql
ALTER TABLE key_update ADD COLUMN rotated_at_ns BIGINT NOT NULL DEFAULT 0
Leave down.sql blank

Generate application code
cargo run --bin update-schema
This updates the generated schema.rs file. This updates models.rs to reference it and encrypted_store/mod.rs to define queries against the model.

Add a new item called rotated_at_ns in the StoredGroup struct in storage/encrypted_store/group.rs

Write a function called get_rotated_time_checked, which is similar to the function get_installations_time_checked, in order to fetch the rotated_at_ns time stamp.

Then in the create_from_welcome function, set the rotated_at_ns = 0 when creating the StoredGroup.

Write an async function called pre_intent_hook(), which does the following

• Rotate the key if checking the rotated_at_ns == 0
• Call maybe_update_installations()
  Before every GroupIntent::New(...), call the pre_intent_hook() function.

Add a boolean flag as an input of the maybe_update_installations function, set the flag to be true to skip the hook when it is called inside from the pre_intent_hook() function. This is intended to avoid infinite loops and make sure it is not called before the key update intent.

[richardhuaaa]

Idea for test 1:

• Client a makes a group with client B
• Client B creates it from welcome
• Verify no new payloads on client A
• Call pre_intent_hook on client B
• Verify client A receives a key rotation payload
  • Check number of messages == 1
  • Check it is a key rotation - look at consume_message() for example. Need to decrypt the message, get the commit, and check it has an update proposal
• Call pre_intent_hook on client B again
• Verify client A receives nothing new
• Register a new client for the same user as client A
• Call pre_intent_hook on client A
• Verify client B receives both a key rotation for client A and a payload to add the new installation

Idea for test 2:
Client a makes a group with client B
Client b creates it from welcome
Verify no new payloads on client A
Client b sends a message to client A
Verify client A receives a key rotation and then the message

[richardhuaaa]

Please see #1108