[avalanche] Add a getavaaddr message
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Authored by Fabien on Jan 14 2022, 10:34.

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tyler-smith

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rABC8a1cbd16b87f: [avalanche] Add a getavaaddr message

Summary

This is part of the active peer discovery. This new message is equivalent to the standard getaddr message and asks for the best avalanche peers, i.e. the ones with the highest availability score. The response use the standard addr message.

For now this does not come with any of the privacy features of the getaddr message, this can be added in follow-up diffs if needed. The messages are limited to one every 10 minutes to prevent a peer from exhausting our resources by spamming with getavaaddr.

Ref T1696.

Test Plan

ninja all check-all

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rABC Bitcoin ABC

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Event Timeline

Fabien created this revision.Jan 14 2022, 10:34

Herald added a reviewer: Restricted Project. · View Herald TranscriptJan 14 2022, 10:34

Fabien requested review of this revision.Jan 14 2022, 10:34

Harbormaster completed remote builds in B17912: Diff 31810.Jan 14 2022, 10:50

tyler-smith added a subscriber: tyler-smith.Jan 21 2022, 07:05

tyler-smith added inline comments.

src/net_processing.cpp
4611 ↗	(On Diff #31810)	Am I understanding correctly that the AvailabilityScore is measuring how responsive that node has been to polls?

Fabien marked an inline comment as done.Jan 21 2022, 08:07

Fabien added inline comments.

src/net_processing.cpp
4611 ↗	(On Diff #31810)	You're correct. The score is an EWMA computation of the received votes minus the emitted polls. So the score will increase over time as the node is polled and is answering, remain zero if the node is not polled, and decrease if the node is not responding. By filtering for score > 0 we only keep the nodes that have been polled and have answered most of the polls.

tyler-smith added inline comments.Feb 2 2022, 05:44

test/functional/abc_p2p_getavaaddr.py
29 ↗	(On Diff #31810)	What is this lock that doesn't seem to be on other uses of this var?

Fabien marked an inline comment as done.Feb 2 2022, 07:16

Fabien added inline comments.

test/functional/abc_p2p_getavaaddr.py
29 ↗	(On Diff #31810)	The `P2PInterface` class have callback methods for the p2p events. The `on_xxx()` methods are such callbacks and are already locking the `p2p_lock` (see the `on_message()` method in `/test/functional/test_framework/p2p.py` for details). The `get_received_addrs()` method on the other hand is not overriden from `P2PInterface` and needs the lock because it accesses the `received_addrs` members which can be set concurrently by `on_addr()`. Note that the `addr_received()` is also doing the same but here the lock is not really needed due to the nature of the check.