`maxConns` option is ignored for incoming connections

[feross]

The maxConns option is currently ignored for incoming connections, so there's effectively no limit the number of incoming connections that we accept.

For TCP, we could just immediately destroy the incoming connection, or perhaps pause the server somehow to avoid accepting in the first place?
For WebRTC, we should consider not ever returning an offer when we're at capacity, since doing the whole signaling process is expensive (webrtc conns are a limited resource; and trackers have limited resources)

[BenjaminLawson]

we should consider not ever returning an offer when we're at capacity

If all of the peers in a swarm are at capacity, and a new peer joins, what should happen? Won't new peers be unable to join the swarm?

See: http://blog.libtorrent.org/2012/12/swarm-connectivity/

I propose that we use Kademlia's xor distance algorithm to decide to accept or reject a peer based on id, and drop the current peer with the greatest distance. A problem is that the swarm is easy to attack, as mentioned in the article, unless you use ip addresses.

Edit: I've tested this out with bittorrent-tracker and it works.

[stale]

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