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Fix couple of old fields and add nonce field to Ping/Pong so that the protocol is slightly more robust when accepting a Pong from remote peer.
Ping/Pong is used to test the aliveness of the remote peer and it works by periodically sending a Ping message and expecting a response to it within some predefined time period. This commit implements this functionality as a state machine on top of the asynchronous protocol by introducing substates to the default listening state of the `PeerState` enum. This allows the Ping/Pong functionality to follow a certain path and catch errors where appropriate while still allowing the remote peer to essentially send anything they want, as long as they reply to the Ping message in time and with correct nonce.
altonen
requested review from
TheQuantumPhysicist,
erubboli,
iljakuklic,
muursh and
zorvan
as code owners
January 13, 2022 05:53
muursh
reviewed
Jan 13, 2022
muursh
reviewed
Jan 13, 2022
muursh
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Jan 13, 2022
TheQuantumPhysicist
approved these changes
Jan 14, 2022
TheQuantumPhysicist
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Other than the few comments I made, it looks fine.
Instead of matching both state and message type at the same time, match the state first, then call an appropriate function for that state and match the message type in that function to handle the (state, message type) combination. Additionally, add some comments, reword an error message and rename a few tests functions to be more descriptive.
muursh
approved these changes
Jan 17, 2022
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This PR implements the Ping/Pong functionality and it's implemented as a state machine on top of the async protocol, i.e., the remote peer can send messages that don't relate to the Ping/Pong functionality in any way but as long as they sent the Pong in time, the connectivity check is concluded as successful. If the remote doesn't respond in time or it responds each time with an invalid nonce, the connection is closed as unresponsive.
This is once again quite a big PR but there's no meaningful way to split it into parts and if it's any solace, there's almost 800 lines of tests and a lot of comments.