distributed-key-value-store.rs

// Copyright 20l9 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any person obtaining a
// copy of this software and associated documentation files (the "Software"),
// to deal in the Software without restriction, including without limitation
// the rights to use, copy, modify, merge, publish, distribute, sublicense,
// and/or sell copies of the Software, and to permit persons to whom the
// Software is furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
// OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// DEALINGS IN THE SOFTWARE.

//! A basic key value store demonstrating libp2p and the mDNS and Kademlia protocols.
//!
//! 1. Using two terminal windows, start two instances. If you local network
//!    allows mDNS, they will automatically connect.
//!
//! 2. Type `PUT my-key my-value` in terminal one and hit return.
//!
//! 3. Type `GET my-key` in terminal two and hit return.
//!
//! 4. Close with Ctrl-c.
//!
//! You can also store provider records instead of key value records.
//!
//! 1. Using two terminal windows, start two instances. If you local network
//!    allows mDNS, they will automatically connect.
//!
//! 2. Type `PUT_PROVIDER my-key` in terminal one and hit return.
//!
//! 3. Type `GET_PROVIDERS my-key` in terminal two and hit return.
//!
//! 4. Close with Ctrl-c.

use async_std::{io, task};
use futures::prelude::*;
use libp2p::kad::record::store::MemoryStore;
use libp2p::kad::{
    AddProviderOk,
    Kademlia,
    KademliaEvent,
    PeerRecord,
    PutRecordOk,
    QueryResult,
    Quorum,
    Record,
    record::Key,
};
use libp2p::{
    NetworkBehaviour,
    PeerId,
    Swarm,
    development_transport,
    identity,
    mdns::{Mdns, MdnsConfig, MdnsEvent},
    swarm::NetworkBehaviourEventProcess
};
use std::{error::Error, task::{Context, Poll}};

#[async_std::main]
async fn main() -> Result<(), Box<dyn Error>> {
    env_logger::init();

    // Create a random key for ourselves.
    let local_key = identity::Keypair::generate_ed25519();
    let local_peer_id = PeerId::from(local_key.public());

    // Set up a an encrypted DNS-enabled TCP Transport over the Mplex protocol.
    let transport = development_transport(local_key).await?;

    // We create a custom network behaviour that combines Kademlia and mDNS.
    #[derive(NetworkBehaviour)]
    struct MyBehaviour {
        kademlia: Kademlia<MemoryStore>,
        mdns: Mdns
    }

    impl NetworkBehaviourEventProcess<MdnsEvent> for MyBehaviour {
        // Called when `mdns` produces an event.
        fn inject_event(&mut self, event: MdnsEvent) {
            if let MdnsEvent::Discovered(list) = event {
                for (peer_id, multiaddr) in list {
                    self.kademlia.add_address(&peer_id, multiaddr);
                }
            }
        }
    }

    impl NetworkBehaviourEventProcess<KademliaEvent> for MyBehaviour {
        // Called when `kademlia` produces an event.
        fn inject_event(&mut self, message: KademliaEvent) {
            match message {
                KademliaEvent::QueryResult { result, .. } => match result {
                    QueryResult::GetProviders(Ok(ok)) => {
                        for peer in ok.providers {
                            println!(
                                "Peer {:?} provides key {:?}",
                                peer,
                                std::str::from_utf8(ok.key.as_ref()).unwrap()
                            );
                        }
                    }
                    QueryResult::GetProviders(Err(err)) => {
                        eprintln!("Failed to get providers: {:?}", err);
                    }
                    QueryResult::GetRecord(Ok(ok)) => {
                        for PeerRecord { record: Record { key, value, .. }, ..} in ok.records {
                            println!(
                                "Got record {:?} {:?}",
                                std::str::from_utf8(key.as_ref()).unwrap(),
                                std::str::from_utf8(&value).unwrap(),
                            );
                        }
                    }
                    QueryResult::GetRecord(Err(err)) => {
                        eprintln!("Failed to get record: {:?}", err);
                    }
                    QueryResult::PutRecord(Ok(PutRecordOk { key })) => {
                        println!(
                            "Successfully put record {:?}",
                            std::str::from_utf8(key.as_ref()).unwrap()
                        );
                    }
                    QueryResult::PutRecord(Err(err)) => {
                        eprintln!("Failed to put record: {:?}", err);
                    }
                    QueryResult::StartProviding(Ok(AddProviderOk { key })) => {
                        println!("Successfully put provider record {:?}",
                            std::str::from_utf8(key.as_ref()).unwrap()
                        );
                    }
                    QueryResult::StartProviding(Err(err)) => {
                        eprintln!("Failed to put provider record: {:?}", err);
                    }
                    _ => {}
                }
                _ => {}
            }
        }
    }

    // Create a swarm to manage peers and events.
    let mut swarm = {
        // Create a Kademlia behaviour.
        let store = MemoryStore::new(local_peer_id.clone());
        let kademlia = Kademlia::new(local_peer_id.clone(), store);
        let mdns = task::block_on(Mdns::new(MdnsConfig::default()))?;
        let behaviour = MyBehaviour { kademlia, mdns };
        Swarm::new(transport, behaviour, local_peer_id)
    };

    // Read full lines from stdin
    let mut stdin = io::BufReader::new(io::stdin()).lines();

    // Listen on all interfaces and whatever port the OS assigns.
    Swarm::listen_on(&mut swarm, "/ip4/0.0.0.0/tcp/0".parse()?)?;

    // Kick it off.
    let mut listening = false;
    task::block_on(future::poll_fn(move |cx: &mut Context<'_>| {
        loop {
            match stdin.try_poll_next_unpin(cx)? {
                Poll::Ready(Some(line)) => handle_input_line(&mut swarm.kademlia, line),
                Poll::Ready(None) => panic!("Stdin closed"),
                Poll::Pending => break
            }
        }
        loop {
            match swarm.poll_next_unpin(cx) {
                Poll::Ready(Some(event)) => println!("{:?}", event),
                Poll::Ready(None) => return Poll::Ready(Ok(())),
                Poll::Pending => {
                    if !listening {
                        if let Some(a) = Swarm::listeners(&swarm).next() {
                            println!("Listening on {:?}", a);
                            listening = true;
                        }
                    }
                    break
                }
            }
        }
        Poll::Pending
    }))
}

fn handle_input_line(kademlia: &mut Kademlia<MemoryStore>, line: String) {
    let mut args = line.split(" ");

    match args.next() {
        Some("GET") => {
            let key = {
                match args.next() {
                    Some(key) => Key::new(&key),
                    None => {
                        eprintln!("Expected key");
                        return;
                    }
                }
            };
            kademlia.get_record(&key, Quorum::One);
        }
        Some("GET_PROVIDERS") => {
            let key = {
                match args.next() {
                    Some(key) => Key::new(&key),
                    None => {
                        eprintln!("Expected key");
                        return
                    }
                }
            };
            kademlia.get_providers(key);
        }
        Some("PUT") => {
            let key = {
                match args.next() {
                    Some(key) => Key::new(&key),
                    None => {
                        eprintln!("Expected key");
                        return;
                    }
                }
            };
            let value = {
                match args.next() {
                    Some(value) => value.as_bytes().to_vec(),
                    None => {
                        eprintln!("Expected value");
                        return;
                    }
                }
            };
            let record = Record {
                key,
                value,
                publisher: None,
                expires: None,
            };
            kademlia.put_record(record, Quorum::One).expect("Failed to store record locally.");
        },
        Some("PUT_PROVIDER") => {
            let key = {
                match args.next() {
                    Some(key) => Key::new(&key),
                    None => {
                        eprintln!("Expected key");
                        return;
                    }
                }
            };

            kademlia.start_providing(key).expect("Failed to start providing key");
        }
        _ => {
            eprintln!("expected GET, GET_PROVIDERS, PUT or PUT_PROVIDER");
        }
    }
}