Implementation of the /ipfs/id/1.0.0 protocol. Allows a node A to query another node B which information B knows about A. Also includes the addresses B is listening on.

When two nodes connect to each other, the listening half sends a message to the dialing half, indicating the information, and then the protocol stops.

Usage

Both low-level and high-level usages are available.

High-level usage through the IdentifyTransport struct

This crate provides the IdentifyTransport struct, which wraps around a Transport and an implementation of Peerstore. IdentifyTransport is itself a transport that accepts multiaddresses of the form /p2p/... or /ipfs/....

Note: All the documentation refers to /p2p/..., however /ipfs/... is also supported.

If you dial a multiaddr of the form /p2p/..., then the IdentifyTransport will look into the Peerstore for any known multiaddress for this peer and try to dial them using the underlying transport. If you dial any other multiaddr, then it will dial this multiaddr using the underlying transport, then negotiate the identify protocol with the remote in order to obtain its ID, then add it to the peerstore, and finally dial the same multiaddr again and return the connection.

Listening doesn't support multiaddresses of the form /p2p/... (because that wouldn't make sense). Any address passed to listen_on will be passed directly to the underlying transport.

Whenever a remote connects to us, either through listening or through next_incoming, the IdentifyTransport dials back the remote, upgrades the connection to the identify protocol in order to obtain the ID of the remote, stores the information in the peerstore, and finally only returns the connection. From the exterior, the multiaddress of the remote is of the form /p2p/.... If the remote doesn't support the identify protocol, then the socket is closed.

Because of the behaviour of IdentifyProtocol, it is recommended to build it on top of a ConnectionReuse.

Low-level usage through the IdentifyProtocolConfig struct

The IdentifyProtocolConfig struct implements the ConnectionUpgrade trait. Using it will negotiate the identify protocol.

The output of the upgrade is a IdentifyOutput. If we are the dialer, then IdentifyOutput will contain the information sent by the remote. If we are the listener, then it will contain a IdentifySender struct that can be used to transmit back to the remote the information about it.