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protocols/kad/behaviour: Remove false assert on connected_peers (#2120)

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Given the following scenario:

1. Remote peer X connects and is added to `connected_peers`.
2. Remote peer X opens a Kademlia substream and thus confirms that it supports
   the Kademlia protocol.
3. Remote peer X is added to the routing table as `Connected`.
4. Remote peer X disconnects and is thus marked as `Disconnected` in the routing
   table.
5. Remote peer Y connects and is added to `connected_peers`.
6. Remote peer X re-connects and is added to `connected_peers`.
7. Remote peer Y opens a Kademlia substream and thus confirms that it supports
   the Kademlia protocol.
8. Remote peer Y is added to the routing table. Given that the bucket is already
   full the call to `entry.insert` returns `kbucket::InsertResult::Pending {
   disconnected }` where disconnected is peer X.

While peer X is in `connected_peers` it has not yet (re-) confirmed that it
supports the Kademlia routing protocol and thus is still tracked as
`Disconnected` in the routing table. The `debug_assert` removed in this pull
request does not capture this scenario.
This commit is contained in:
Max Inden 2021-07-08 14:48:40 +02:00 committed by GitHub
parent a414afd83c
commit 05a4b16bb3
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2 changed files with 16 additions and 5 deletions
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3
protocols/kad/CHANGELOG.md
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@ -11,7 +11,10 @@
- Expose kbucket range on `KademliaEvent::RoutingUpdated` (see [PR 2087]).
- Remove false `debug_assert` on `connected_peers` (see [PR 2120]).
[PR 2087]: https://github.com/libp2p/rust-libp2p/pull/2087
[PR 2120]: https://github.com/libp2p/rust-libp2p/pull/2120
# 0.30.0 [2021-04-13]

18
protocols/kad/src/behaviour.rs
View File

@ -1042,15 +1042,23 @@ where
));
},
kbucket::InsertResult::Pending { disconnected } => {
debug_assert!(!self.connected_peers.contains(disconnected.preimage()));
let address = addresses.first().clone();
self.queued_events.push_back(NetworkBehaviourAction::GenerateEvent(
KademliaEvent::PendingRoutablePeer { peer, address }
));
self.queued_events.push_back(NetworkBehaviourAction::DialPeer {
peer_id: disconnected.into_preimage(),
condition: DialPeerCondition::Disconnected
})
// `disconnected` might already be in the process of re-connecting.
// In other words `disconnected` might have already re-connected but
// is not yet confirmed to support the Kademlia protocol via
// [`KademliaHandlerEvent::ProtocolConfirmed`].
//
// Only try dialing peer if not currently connected.
if !self.connected_peers.contains(disconnected.preimage()) {
self.queued_events.push_back(NetworkBehaviourAction::DialPeer {
peer_id: disconnected.into_preimage(),
condition: DialPeerCondition::Disconnected
})
}
},
}
}