Crate multistream_select

Expand description

Multistream-select

This crate implements the multistream-select protocol, which is the protocol used by libp2p to negotiate which protocol to use with the remote.

Note: This crate is used by the internals of libp2p, and it is not required to understand it in order to use libp2p.

Whenever a new connection or a new multiplexed substream is opened, libp2p uses multistream-select to negotiate with the remote which protocol to use. After a protocol has been successfully negotiated, the stream (i.e. the connection or the multiplexed substream) immediately stops using multistream-select and starts using the negotiated protocol.

Protocol explanation

The dialer has two options available: either request the list of protocols that the listener supports, or suggest a protocol. If a protocol is suggested, the listener can either accept (by answering with the same protocol name) or refuse the choice (by answering “not available”).

Examples

For a dialer:

use bytes::Bytes;
use multistream_select::dialer_select_proto;
use futures::{Future, Sink, Stream};
use tokio_tcp::TcpStream;
use tokio::runtime::current_thread::Runtime;

#[derive(Debug, Copy, Clone)]
enum MyProto { Echo, Hello }

let client = TcpStream::connect(&"127.0.0.1:10333".parse().unwrap())
    .from_err()
    .and_then(move |connec| {
        let protos = vec![b"/echo/1.0.0", b"/echo/2.5.0"];
        dialer_select_proto(connec, protos).map(|r| r.0)
    });

let mut rt = Runtime::new().unwrap();
let negotiated_protocol = rt.block_on(client).expect("failed to find a protocol");
println!("negotiated: {:?}", negotiated_protocol);

listener_select_proto

Helps selecting a protocol amongst the ones supported.

Type Definitions

DialerSelectFuture

Future, returned by dialer_select_proto, which selects a protocol and dialer either sequentially of by considering all protocols in parallel.

Crate multistream_select

Multistream-select

Protocol explanation

Examples

Modules

Structs

Enums

Functions

Type Definitions