Transport interface for libp2p
$ npm i @libp2p/interface-transport
The primary goal of this module is to enable developers to pick and swap their transport module as they see fit for their libp2p installation, without having to go through shims or compatibility issues. This module and test suite were heavily inspired by abstract-blob-store, interface-stream-muxer and others.
Publishing a test suite as a module lets multiple modules all ensure compatibility since they use the same test suite.
The purpose of this interface is not to reinvent any wheels when it comes to dialing and listening to transports. Instead, it tries to provide a uniform API for several transports through a shimmed interface.
Include this badge in your readme if you make a module that is compatible with the interface-transport API. You can validate this by running the tests.
/* eslint-env mocha */
'use strict'
const tests = require('libp2p-interfaces-compliance-tests/transport')
const multiaddr = require('@multiformats/multiaddr')
const YourTransport = require('../src')
describe('compliance', () => {
tests({
setup (init) {
let transport = new YourTransport(init)
const addrs = [
multiaddr('valid-multiaddr-for-your-transport'),
multiaddr('valid-multiaddr2-for-your-transport')
]
const network = require('my-network-lib')
const connect = network.connect
const connector = {
delay (delayMs) {
// Add a delay in the connection mechanism for the transport
// (this is used by the dial tests)
network.connect = (...args) => setTimeout(() => connect(...args), delayMs)
},
restore () {
// Restore the connection mechanism to normal
network.connect = connect
}
}
return { transport, addrs, connector }
},
teardown () {
// Clean up any resources created by setup()
}
})
})
A valid transport (one that follows the interface defined) must implement the following API:
Table of contents:
Transport
new Transport({ upgrader, ...[options] })
<Promise> transport.dial(multiaddr, [options])
<Multiaddr[]> transport.filter(multiaddrs)
transport.createListener([options], handlerFunction)
transport.Listener
<Promise> listener.listen(multiaddr)
listener.getAddrs()
<Promise> listener.close([options])
Upgraders have 2 methods: upgradeOutbound
and upgradeInbound
.
upgradeOutbound
must be called and returned by transport.dial
.upgradeInbound
must be called and the results must be passed to the createListener
handlerFunction
and the connection
event handler, any time a new connection is created.const connection = await upgrader.upgradeOutbound(multiaddrConnection)
const connection = await upgrader.upgradeInbound(multiaddrConnection)
The Upgrader
methods take a MultiaddrConnection and will return an interface-connection
instance.
MultiaddrConnection
sink<function(source)>
: A streaming iterable sinksource<AsyncIterator>
: A streaming iterable sourceclose<function(Error)>
: A method for closing the connectionconn
: The raw connection of the transport, such as a TCP socket.remoteAddr<Multiaddr>
: The remote Multiaddr
of the connection.[localAddr<Multiaddr>]
: An optional local Multiaddr
of the connection.timeline<object>
: A hash map of connection time eventsopen<number>
: The time in ticks the connection was openedclose<number>
: The time in ticks the connection was closedconst transport = new Transport({ upgrader, ...[options] })
Creates a new Transport instance. options
is an JavaScript object that should include the necessary parameters for the transport instance. Options MUST include an Upgrader
instance, as Transports will use this to return interface-connection
instances from transport.dial
and the listener handlerFunction
.
Note: Why is it important to instantiate a transport - Some transports have state that can be shared between the dialing and listening parts. For example with libp2p-webrtc-star, in order to dial a peer, the peer must be part of some signaling network that is shared with the listener.
const connection = await transport.dial(multiaddr, [options])
This method uses a transport to dial a Peer listening on multiaddr
.
multiaddr
must be of the type multiaddr
.
[options]
the options that may be passed to the dial. Must support the signal
option (see below)
Dial MUST call and return upgrader.upgradeOutbound(multiaddrConnection)
. The upgrader will return an interface-connection instance.
The dial may throw an Error
instance if there was a problem connecting to the multiaddr
.
Dials may be cancelled using an AbortController
:
const { AbortError } = require('libp2p-interfaces/src/transport/errors')
const controller = new AbortController()
try {
const conn = await mytransport.dial(ma, { signal: controller.signal })
// Do stuff with conn here ...
} catch (err: any) {
if(err.code === AbortError.code) {
// Dial was aborted, just bail out
return
}
throw err
}
// ----
// In some other part of the code:
controller.abort()
// ----
const supportedAddrs = await transport.filter(multiaddrs)
When using a transport its important to be able to filter out multiaddr
s that the transport doesn't support. A transport instance provides a filter method to return only the valid addresses it supports.
multiaddrs
must be an array of type multiaddr
.
Filter returns an array of multiaddr
.
const listener = transport.createListener([options], handlerFunction)
This method creates a listener on the transport. Implementations MUST call upgrader.upgradeInbound(multiaddrConnection)
and pass its results to the handlerFunction
and any emitted connection
events.
options
is an optional object that contains the properties the listener must have, in order to properly listen on a given transport/socket.
handlerFunction
is a function called each time a new connection is received. It must follow the following signature: function (conn) {}
, where conn
is a connection that follows the interface-connection
.
The listener object created may emit the following events:
listening
- when the listener is ready for incoming connectionsclose
- when the listener is closedconnection
- (conn
) each time an incoming connection is receivederror
- (err
) each time there is an error on the connectionawait listener.listen(multiaddr)
This method puts the listener in listening
mode, waiting for incoming connections.
multiaddr
is the address that the listener should bind to.
listener.getAddrs()
This method returns the addresses on which this listener is listening. Useful when listening on port 0 or any interface (0.0.0.0).
await listener.close([options])
This method closes the listener so that no more connections can be opened on this transport instance.
options
is an optional object that may contain the following properties:
timeout
- A timeout value (in ms) after which all connections on this transport will be destroyed if the transport is not able to close gracefully. (e.g { timeout: 1000 }
)Licensed under either of
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.