https://github.com/libp2p/go-libp2p-kad-dht/issues/147

libp2p DHT modes - Client/Server

• Client mode is default
• Well, it really query-only mode (mostly) versus full mode. The active side is actually the “client” (making requests), the “server” just responds to requests.
• Given enough bad nodes, a DHT becomes unusable.
• we have a ton of nodes behind NATs
  1. Make outbound connections to insert themselves into the DHT.
  2. Cannot accept inbound connections, making it hard to actually traverse the DHT.
• nodes behind NATs won’t be pingable (so they’ll be dropped from routing tables pretty quickly).
• clients are “passive” nodes, this is how it’s done in BitTorrent.

• DHT nodes that have just started may not provide particularly useful responses to some queries

• https://github.com/libp2p/go-libp2p-kad-dht/issues/349

  • The DHT needs the ability to switch between server and client mode.
    • If a peer becomes undialable for some reason, they should move to being only a client, but if a peer becomes dialable and suitable for being a full dht node, they should be able to without rebooting.

libp2p functions to use:

// returns the diversity stats for the Routing Table.
IpfsDHT.GetRoutingTableDiversityStats()

// allows introspection of the operation mode of the DHT
// Client & Server modes; Server mode allows for answering queries
IpfsDHT.Mode()

// looks for a peer with a given ID connected to this dht and returns the peer and the table it was found in
IpfsDHT.FindLocal(id peer.ID) peer.AddrInfo

host.Peerstore().Peers()

AutoNAT

libp2p RPC

• github.com/libp2p/go-libp2p-gorpc
• provides RPC support on top of libp2p in the same way that net/rpc does on HTTP

Third-party tutorials

• https://ldej.nl/post/building-an-echo-application-with-libp2p/

libp2p concepts

• Host

  • contains all the core functionalities you require connecting one peer to another
  • contains ID, which is an identity of the peer

• Stream

  • communication channel between two peers
• Peerstore