Crate communication

Stronghold Communication

This crate enables strongholds on different devices and in different networks to communicate with each other. The main basis for its functionality is the libp2p crate, which is a system of protocols, specifications and libraries that enable the development of peer-to-peer network applications

The library provides two options to use communication, either directly with the [P2PNetworkBehaviour], or by using the [CommunicationActor] within a [ActorSystem].

P2PNetworkBehaviour

The P2pNetworkBehaviour implements the [NetworkBehaviour] by combining multiple protocols of Libp2p:

• Multiplexing following the Yamux specification
• Noise: Encryption of the communication using the Noise protocol with XX-Handshake
• Multicast DNS: Enable Peer Discovery in a local network
• Identify Protocol: Receive identifying information like the PeerId and listening addresses when connecting to a new peer.
• Request-Response Protocol: Allows sending direct request/response messages between Peers; it expects a response for each request

Upon creating a new instance, a transport is created and upgraded, and combined with the P2PNetworkBehaviour into a [ExpandedSwarm]. This Swarm is returned to the caller and serves as entry-point for all communication to other peers. Additional to the Libp2p methods of the [ExpandedSwarm], it enables sending outbound messages, and manages the known peers. Incoming [P2PEvents] can be handled by polling from the swarm, e.g. via the [next] method.

Example

use async_std::task;
use communication::behaviour::{BehaviourConfig, P2PNetworkBehaviour};
use libp2p::identity::Keypair;
use serde::{Deserialize, Serialize};

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum Request {
    Ping,
}

#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum Response {
    Pong,
}

let local_keys = Keypair::generate_ed25519();
let config = BehaviourConfig::default();
let mut swarm = task::block_on(P2PNetworkBehaviour::<Request, Response>::init_swarm(local_keys, config))
    .expect("Init swarm failed.");

CommunicationActor

The [CommunicationActor] is using the riker crate to implement the actor pattern.
When creating a new [CommunicationActor], the actor creates a [P2PNetworkBehaviour] and continuously polls for events, incoming requests are sent to the client actor that has to be provided in the [CommunicationConfig].

All swarm interaction, and configuration of the [CommunicationActor] is accomplished by sending the appropriate [CommunicationRequest] to it, for each [CommunicationRequest] a [CommunicationResults] is returned to the sender, this also allows using the ask pattern.

Firewall

The communication actor implements a firewall that checks the permission of each outgoing and incoming requests and drops them if the necessary permission has not been set. The required [ToPermissionVariants] trait for messages can be derived with the [communication-macros], this allows in case of enum Request types to accept specific variants while rejecting others.

Modules

actor	Actor
behaviour	P2PNetworkBehaviour
libp2p	Re-export libp2p types.