Add support for Addrs {listen, announce, noAnnounce}

[daviddias]

With https://github.com/libp2p/js-libp2p/pull/166/files, the libp2p constructor will be fully refactored and with it comes the libp2p config.

We want to give the user the ability to(with example):

addresses: {                  // Multiaddrs
  listen: []                  // To start transport listener
  announce: []                // To announce/share with the network (i.e DNS addr)
  noAnnounce: []              // To keep private
},

Proposed in: #166 (comment)

[JGAntunes]

Hello! 👋

Just found this through - ipfs/js-ipfs#1865 - and thought maybe I could help out here?

What's the plan for these addresses vs the ones coming for the PeerInfo instance?

[jacobheun]

The go-ipfs docs are a helpful reference here, https://github.com/ipfs/go-ipfs/blob/v0.4.18/docs/config.md#addresses, I think js-ipfs will eventually need to be updated to support Announce and NoAnnounce once libp2p has support for this.

Here are my thoughts for each piece (with untested pseudo code):

listen

These addresses will be passed to the transports for listening on startup. Any existing multiaddrs in PeerInfo will also be listened to.

// Pre startup:
const listenAddrs = [...options.addresses.listen, ...peerInfo.multiaddrs.toArray()]

announce

These addresses would be added to PeerInfo once listening is completed. They are an amendment to the multiaddrs already in PeerInfo and as such, would not replace any existing addresses.

Note: On listening, a transport may replace multiaddrs in peerInfo with improved addresses. For example tcp may replace /ip4/0.0.0.0/tcp/0 with something like /ip4/0.0.0.0/tcp/8989.

// Post listening
options.addresses.announce.forEach(addr => peerInfo.multiaddrs.add(addr))

noAnnounce

This is a list of addresses that should be removed from PeerInfo, as any address in PeerInfo will be advertised to peers.

Note: noAnnounce should take into account encapsulated addresses. For example, if I add /ip4/127.0.0.1 to noAnnounce, I expect addresses like /ip4/127.0.0.1/tcp/8080/ipfs/Qm to be filtered out.

// Pre announce filtering
peerInfo.multiaddrs.forEach(addr => {
  if (options.addresses.noAnnounce.find(addr)) {
    peerInfo.multiaddrs.delete(addr)
  }
})

What do you think? cc @alanshaw @vasco-santos

---

Edit

Observed Addresses

When we run identify with another peer they may respond with a list of observed addresses they have for us. We should do some validation of those addresses prior to adding them to our address list. reference: libp2p/js-libp2p-switch#330 (comment)

[vasco-santos]

I like the approach suggested by @jacobheun

[jacobheun]

This is done