port Order machine about magic-wormhole.rs HOT 3 CLOSED

Oh, one gotcha to look out for. The current way that events are processed means that everything is an "eventual send" (e.g. when an event is processed, any events it emits are appended to the end of a queue, and the main execute() loop pulls events from the front of this queue), so the following sequence of events would violate the order of delivery that Order is supposed to provide:

• Order gets non-PAKE message: queues it, emits nothing
• Order gets PAKE message: emits Key.got_pake, emits Receive.got_message (for queued message)
• action queue is now: [Key.got_pake, Receive.got_message]
• Key.got_pake computes shared key, emits Receive.got_key
• action queue is now: [Receive.got_message, Receive.got_key]
• Key.got_message runs, breaks because it hasn't gotten the key yet

I'm not yet sure what a clean solution would be. Maybe change the way execute works to do more of a depth-first traversal of the action queue (push the emitted events onto the front of the queue, rather than the back).

from magic-wormhole.rs.

I think most of it is implemented. When I get to the receive parts, I will revisit Order state machine.

from magic-wormhole.rs.

This is done now, however that eventual-send issue might still be a problem. I'll open a separate ticket for it.

from magic-wormhole.rs.