It's often useful to have some idea of when a connection is lost. This is especially true when working with multiplexed connections where a given stream may become unusable because it's underlying connection has been closed.

I'm quite fond of the approach taken by https://github.com/lucas-clemente/quic-go. QUIC-go's Session and Stream interfaces export the Context() method. The returned context expires when the Session/Stream is no longer usable.

Does this seem feasible in libp2p?

It is currently impossible to assign values to the Extra map from within a net.Notifiee method. Indeed, in e.g. Notifiee.Connected(), conn.Stat().Extra is nil.

It would be nice to have an initialized map, here, as it allows library users to pass around contextual information. An alternative might be to extend #32 to support a WithContext() method similar to http.Request. This would allow users to bind contextual data to connections/streams via context.Context, which feels a bit more idiomatic.

Thoughts?

• Filters
• Backpressure
• Connection information (ways to get the stream muxer, etc.).

Please add a LICENSE file so that this package will be vendor-able by third parties.

Imagine we just dialed a peer with the multiaddress of /ip4/127.0.0.1/tcp/5002/p2p/QmdPU7PfRyKehdrP5A3WqmjyD6bhVpU1mLGKppa2FjGDjZ/p2p-circuit/p2p/QmVT6GYwjeeAF5TR485Yc58S3xRF5EFsZ5YAF4VcP3URHt

h.Network().Notify(&inet.NotifyBundle{
    ConnectedF: func(net inet.Network, conn inet.Conn) {
      // Must be handled in a goroutine as this callback cannot be blocking.
      go func() {

        s, err := h.NewStream(
          context.Background(),
          conn.RemotePeer(), // QmdPU7PfRyKehdrP5A3WqmjyD6bhVpU1mLGKppa2FjGDjZ
          handshakeProtocol,
        )
     ...
     ...
   }()
 })

conn.RemotePeer() returns the peer ID of the circuit/relay node (QmdPU7PfRyKehdrP5A3WqmjyD6bhVpU1mLGKppa2FjGDjZ), not the specific peer (QmVT6GYwjeeAF5TR485Yc58S3xRF5EFsZ5YAF4VcP3URHt). As a result, the stream is with the wrong peer.

I can't figure out where the implementation of the Conn interface is so I have no idea where to start investigating this further.

Additionally, it would be nice if conn.NewStream(procotol) worked. It would be intuitive to call this when I want to open/use a stream with the remote peer.

Currently, one has to use AwaitEOF. However, doing this asynchronously ties up a goroutine. This sucks.

See: ipfs/kubo#5247

Most stream implementations (e.g., yamux, spdy, quic) support half-open streams. This means that Close only closes one side.

We need a Reset() method to force-close the connection (closing both sides).

See: ipfs/kubo#3651 (comment)

For example:

• DialAddr(peer, multiaddr)
• Dial(peer)
• Error(type, peer, multiaddr)