[switch] Filter out matching IP:PORT pairs in Identify about js-libp2p

[tullrich]

It appears this is an old issue, but I am still getting this when using the js-libp2p-mdns discovery module. It seems peers advertise the loopback address, which causes any listening peers to connect to themselves (while believing that they have successfully connected to the remote peer).

I am not seeing the js-libp2p-secio handshake reject this, in fact, they connection establishes an encrypted channel and mux on both ends and raises two 'peer:connect' events to my application. Is there a workaround for this that would prevent any dials on addresses that are obviously myself?

[tullrich]

Sure @dryajov, thank you for your quick response! I have pushed a small demo of this bug here.

This demo setups a simple libp2p bundle with TCP transport, mDNS discovery, and SECIO. It attempts to dial any discovered peers. When run from two hosts on the same local network I get the following output:

This Peer ID:  QmbQvNDBqvyDEP3LUmCNJYv8bLyxA2BP8bSYYRGVKr2Avv
Listening on addresses: 
 [ '/ip4/127.0.0.1/tcp/4043/ipfs/QmbQvNDBqvyDEP3LUmCNJYv8bLyxA2BP8bSYYRGVKr2Avv',
  '/ip4/10.20.0.123/tcp/4043/ipfs/QmbQvNDBqvyDEP3LUmCNJYv8bLyxA2BP8bSYYRGVKr2Avv' ]
Discovered: QmXQhdGGFJbGcQmUR4o4j4meVNR97u1GWaJt1PpfraVz1t
Connection established to: QmXQhdGGFJbGcQmUR4o4j4meVNR97u1GWaJt1PpfraVz1t
Connection established to: QmbQvNDBqvyDEP3LUmCNJYv8bLyxA2BP8bSYYRGVKr2Avv

The two 'peer:connect' events printed actually come from both halves of the same connection (since we have connected to our self) and the remote peer is not involved at all beyond the discovery broadcast. This can be verified with the full debug log found here. You can see that the advertised addresses from the remote peer contain a loopback address that we successfully connect to during dialMany().

Note that this will not occur if you attempt to connect two nodes from different ports on the same machine since the advertised loopback address will correctly reach the remote peer.

[dryajov]

@tullrich that certainly sounds like a bug, could you please provide a snippet that reproduces it?

[dryajov]

@tullrich thanks! I'll check it out shortly.

[p-shahi]

The prescribed behavior by this issue isn't in accordance with the identify spec: https://github.com/libp2p/specs/tree/master/identify#identifypush

Closing this for now