swift-libp2p / swift-libp2p-kad-dht

A Kademlia based Distributed Hash Table Implementation for Libp2p

LibP2PKadDHT

A Kademlia Distributed Hash Table for LibP2P

Table of Contents

• Overview
• Install
• Usage
  • Example
  • API
• Contributing
• Credits
• License

Overview

The Kademlia Distributed Hash Table (DHT) subsystem in libp2p is a DHT implementation largely based on the Kademlia [0] whitepaper, augmented with notions from S/Kademlia [1], Coral [2] and the BitTorrent DHT.

DHT operations

The libp2p Kademlia DHT offers the following types of operations:

• Peer routing

  • Finding the closest nodes to a given key via FIND_NODE.

• Value storage and retrieval

  • Storing a value on the nodes closest to the value's key by looking up the closest nodes via FIND_NODE and then putting the value to those nodes via PUT_VALUE.

  • Getting a value by its key from the nodes closest to that key via GET_VALUE.

• Content provider advertisement and discovery

  • Adding oneself to the list of providers for a given key at the nodes closest to that key by finding the closest nodes via FIND_NODE and then adding oneself via ADD_PROVIDER.

  • Getting providers for a given key from the nodes closest to that key via GET_PROVIDERS.

In addition the libp2p Kademlia DHT offers the auxiliary bootstrap operation.

Note:

• For more information check out the Kad DHT Spec

Install

Include the following dependency in your Package.swift file

let package = Package(
    ...
    dependencies: [
        ...
        .package(name: "LibP2PKadDHT", url: "https://github.com/swift-libp2p/swift-libp2p-kad-dht.git", .upToNextMajor(from: "0.0.1"))
    ],
    
    ...
)

Usage

Example

check out the tests for more examples

import LibP2PKadDHT

let app = Application(.detect())

/// If you'd like to use the DHT as a DHT...
app.dht.use( .kadDHT )

/// Or if you're just interested in its peer discovery functionality
app.discovery.use(.kadDHT)

API

extension StorageKeys {
    static let MyDHT = "MyDHT"
}

let dht = BasicKadDHT(protocolPrefix: "mydht", version: "1.0.0", k: 20, alpha: 4, peerstore: .shared(app.peerstore) ?? .basicInMemory, kvstore: .basicInMemory...)
app.use(dht, id: .MyDHT)

dht.handle(namespace: "pk", valueAs: PublicKey.self, withValidator: { msg in msg.record.value.multihash == msg.key && msg.key }).onPutSuccess({ msg in ... }).onPutFailed({ msg, error in ...})

dht.handle(namespace: "ipfs", valueAs: IPNSRecord.self, withValidator: { msg in ... }).onPutSuccess({ msg in ... }).onPutFailed({ msg, error in ...})

// ... or ...
app.dht.group("myDHT") { myDHT in
    myDHT.on("pk", validator: ...) { pk in ... }
    myDHT.on("ipld", validator: ...) { ipld in ... }
} 

/// Somewhere else without reference to `dht`
app.dht.getValue(forKey: "Qm12...") { value in .... } //if you only have one DHT running
/// or
app.dhts.for(id: .MyDHT).put(value: Record, forKey: "Qm12...") { success in ... }
/// or
let val = await app.dhts.for(id: "MyDHT").findNode("Qm13...")
let routingTableInfo = await app.dhts.for(id: "MyDHT").routingTableInfo()

}

Contributing

Contributions are welcomed! This code is very much a proof of concept. I can guarantee you there's a better / safer way to accomplish the same results. Any suggestions, improvements, or even just critques, are welcome!

Let's make this code better together! 🤝

Credits

• MPLEX Spec
• [0]: Maymounkov, P., & Mazières, D. (2002). Kademlia: A Peer-to-Peer Information System Based on the XOR Metric. In P. Druschel, F. Kaashoek, & A. Rowstron (Eds.), Peer-to-Peer Systems (pp. 53–65). Berlin, Heidelberg: Springer Berlin Heidelberg.
• [1]: Baumgart, I., & Mies, S. (2014). S / Kademlia : A practicable approach towards secure key-based routing S / Kademlia : A Practicable Approach Towards Secure Key-Based Routing, (June).
• [2]: Freedman, M. J., & Mazières, D. (2003). Sloppy Hashing and Self-Organizing Clusters. In IPTPS. Springer Berlin / Heidelberg. Retrieved from
• bittorrent
• uvarint-spec
• ping
• go-libp2p-xor

License

MIT © 2022 Breth Inc.

swift-libp2p-kad-dht's Issues

Importing Build error

Hi, when i use the Swift Package Manager to import your Library. I get a build error "cannot find type 'ResponseType' in scope".
If I clone the repo and import it as a local library, there are no build errors but none of your examples work. Despite importing LibP2PKadDHT it cannot find classes like BasicKadDHT.

XCode Version 15.0 (15A240d)
iOS 17

How is your package supposed to be used in a project? I saw the installation guide but thats only for importing to another package.

Kind regards