A P2P Network with Golang and libp2p

Peer-to-peer (P2P) networks have become increasingly popular as an alternative to centralized systems. P2P networks allow for direct communication and data sharing between nodes, without relying on a central server.

In this post, I’m assuming that you have some knowledge of working with Golang. We will explore how to develop a P2P network using Golang and the libp2p library.

First some key Concepts of libp2p Link to heading

Libp2p is a networking stack and library modularized to enable many different applications to be built upon it. It provides a set of protocols, such as peer discovery, routing, exchange, and content discovery, that can be used to create a P2P network. You can check the library here.

https://docs.libp2p.io/

Peer Discovery Link to heading

Peer discovery is a fundamental aspect of a P2P network that allows nodes to discover other nodes in the network. This is typically done through a bootstrap node or a distributed hash table (DHT). Libp2p provides a peer discovery module that allows nodes to discover other nodes in the network.

Peer Routing Link to heading

Peer routing is responsible for routing messages between nodes in the network. It uses protocols such as Kademlia or Coral to efficiently route messages. Libp2p provides a peer routing module that can be used to implement peer routing in a P2P network.

Peer Exchange Link to heading

Peer exchange allows nodes to exchange information about other nodes in the network, such as their IP addresses and public keys. This enables nodes to communicate with each other more efficiently, which is essential for sharing data and resources. Libp2p provides a peer exchange module that can be used to implement peer exchange in a P2P network.

Content Discovery Link to heading

Content discovery allows nodes to discover and request content from other nodes in the network. This is typically done through a content-addressed system, such as IPFS. Libp2p provides a content discovery module that can be used to implement content discovery in a P2P network.

Data Storage Link to heading

Data storage is responsible for storing data on the network. It uses distributed storage protocols such as IPFS or BitTorrent to ensure that data is replicated across multiple nodes on the network. Libp2p provides a data storage module that can be used to implement data storage in a P2P network.

Developing a P2P Network Link to heading

To get started, we need to install the libp2p library.

go get github.com/libp2p/go-libp2p

Once we have the library installed, we can create a basic P2P network using the following code:

package main

import (
	"context"
	"fmt"
	"github.com/libp2p/go-libp2p"
	"github.com/libp2p/go-libp2p-core/peer"
)

func main() {
	// Set up a libp2p host
	host, err := libp2p.New(context.Background())
	if err != nil {
		panic(err)
	}

	// Print the host's ID
	fmt.Println("Host ID:", host.ID().Pretty())

	// Connect to another node
	peerInfo, _ := peer.AddrInfoFromP2pAddr("/ip4/127.0.0.1/tcp/1234/p2p/QmPZ8Y7ZpYvZjK7JhDx59EJ7yBkDz4n4QwD4HSR8Z473YH")
	err = host.Connect(context.Background(), *peerInfo)
	if err != nil {
		panic(err)
	}
}

In the example above, we create a new libp2p host and print its ID. We then connect to another node in the network using its peer address.

Next, we can add peer discovery to our network by using a bootstrap node:

package main

import (
	"context"
	"fmt"
	"github.com/libp2p/go-libp2p"
	"github.com/libp2p/go-libp2p-core/peer"
	"github.com/libp2p/go-libp2p-bootstrap"
)

func main() {
	// Set up a libp2p host
	host, err := libp2p.New(context.Background(), libp2p.EnableNATService(), libp2p.NATPortMap())
	if err != nil {
		panic(err)
	}

	// Add a bootstrap node
	peerAddr, _ := peer.AddrInfoFromP2pAddr("/ip4/192.168.0.1/tcp/4001/p2p/QmWtG8q5qzV7pmGkHJBuF7L8YvYg9XaMjHoDvoV2zEgMfB")
	bootstrap.AddAddrs(host, peerAddr, bootstrap.DialTimeout(time.Second*5))

	// Print the host's ID
	fmt.Println("Host ID:", host.ID().Pretty())

	// Wait for the host to connect to the network
	<-host.Network().Notify((*notifiee)(nil))

	// Connect to another node
	peerInfo, _ := peer.AddrInfoFromP2pAddr("/ip4/127.0.0.1/tcp/1234/p2p/QmPZ8Y7ZpYvZjK7JhDx59EJ7yBkDz4n4QwD4HSR8Z473YH")
	err = host.Connect(context.Background(), *peerInfo)
	if err != nil {
		panic(err)
	}
}

We add a bootstrap node to our network using the bootstrap package.

We also enable NAT traversal and port mapping, so that our nodes can communicate with each other even if they are behind a NAT. We then wait for the host to connect to the network before connecting to another node.

Finally, we can add peer routing, peer exchange, content discovery, and data storage to our network using the appropriate libp2p modules.