## Issue Addressed
https://github.com/sigp/lighthouse/issues/4543
## Proposed Changes
- Removes `NotBanned` from `BanResult`, implements `Display` and `std::error::Error` for `BanResult` and changes `ban_result` return type to `Option<BanResult>` which helps returning `BanResult` on `handle_established_inbound_connection`
- moves the check from for banned peers from `on_connection_established` to `handle_established_inbound_connection` to start addressing #4543.
- Removes `allow_block_list` as it's now redundant? Not sure about this one but if `PeerManager` keeps track of the banned peers, no need to send a `Swarm` event for `alow_block_list` to also keep that list right?
## Questions
- #4543 refers:
> More specifically, implement the connection limit behaviour inside the peer manager.
@AgeManning do you mean copying `libp2p::connection_limits::Behaviour`'s code into `PeerManager`/ having it as an inner `NetworkBehaviour` of `PeerManager`/other? If it's the first two, I think it probably makes more sense to have it as it is as it's less code to maintain.
> Also implement the banning of peers inside the behaviour, rather than passing messages back up to the swarm.
I tried to achieve this, but we still need to pass the `PeerManagerEvent::Banned` swarm event as `DiscV5` handles it's node and ip management internally and I did not find a method to query if a peer is banned. Is there anything else we can do from here?
3397612160/beacon_node/lighthouse_network/src/discovery/mod.rs (L931-L940)
Same as the question above, I did not find a way to check if `DiscV5` has the peer banned, so that we could check here and avoid sending `Swarm` events
3397612160/beacon_node/lighthouse_network/src/peer_manager/network_behaviour.rs (L168-L178)
Is there a chance we try to dial a peer that has been banned previously?
Thanks!
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