feat: add identify protocol example

examples/js-libp2p-example-identify/README.md

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+# js-libp2p-example-identify
+
+This example demonstrates how to use the identify protocol in js-libp2p to exchange peer information.
+
+## Requirements
+
+- Node.js version 20 or higher
+- npm version 7 or higher
+
+## Setup
+
+1. Install dependencies:
+   ```console
+   $ npm install
+   ```
+
+2. Run the example in two terminals:
+
+   Terminal 1 (Listener):
+   ```console
+   $ npm start
+   ```
+
+   Terminal 2 (Dialer):
+   ```console
+   $ npm run dial -- <multiaddr>
+   ```
+   Replace `<multiaddr>` with the multiaddr shown in the listener's output.
+
+## How It Works
+
+- The example creates two libp2p nodes: a listener and a dialer
+- The listener starts and displays its peer ID and multiaddrs
+- The dialer connects to the listener using the provided multiaddr
+- When the connection is established, the identify protocol is triggered automatically
+- Both peers exchange and display detailed information about each other
+
+## Example Output
+
+When running the example, you'll see output similar to this:
+
+Listener output:
+```
+Listener node started with peer ID: 12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+Listener multiaddrs: /ip4/127.0.0.1/tcp/37097/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+/ip4/192.168.1.17/tcp/37097/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+/ip4/10.155.221.162/tcp/37097/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+/ip4/127.0.0.1/tcp/37941/ws/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+/ip4/192.168.1.17/tcp/37941/ws/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+/ip4/10.155.221.162/tcp/37941/ws/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+New connection opened: 12D3KooWKYAhezQQqwWvQ8iECUv9R5tTy6639s13ZqrS5tp66Hpd
+
+=== Identify Information ===
+Peer ID: 12D3KooWKYAhezQQqwWvQ8iECUv9R5tTy6639s13ZqrS5tp66Hpd
+Agent Version: js-libp2p/2.8.5 node/21.7.3
+Protocol Version: ipfs/0.1.0
+Supported protocols: [ '/ipfs/id/1.0.0' ]
+Observed address: Multiaddr(/ip4/127.0.0.1/tcp/37097/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp)
+Listen addresses: [
+  '/ip4/127.0.0.1/tcp/41267',
+  '/ip4/192.168.1.17/tcp/41267',
+  '/ip4/10.155.221.162/tcp/41267',
+  '/ip4/127.0.0.1/tcp/45747/ws',
+  '/ip4/192.168.1.17/tcp/45747/ws',
+  '/ip4/10.155.221.162/tcp/45747/ws'
+]
+===========================
+```
+
+Dialer output:
+```
+Dialer node started with peer ID: 12D3KooWKYAhezQQqwWvQ8iECUv9R5tTy6639s13ZqrS5tp66Hpd
+Dialing to: /ip4/127.0.0.1/tcp/37097/p2p/12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+New connection opened: 12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+Successfully dialed to target node
+
+=== Identify Information ===
+Peer ID: 12D3KooWF496AdcXPuXgiUeGpRVR29QZeRyyiyYK3dsmgyhqbacp
+Agent Version: js-libp2p/2.8.5 node/21.7.3
+Protocol Version: ipfs/0.1.0
+Supported protocols: [ '/ipfs/id/1.0.0' ]
+Observed address: Multiaddr(/ip4/127.0.0.1/tcp/49744/p2p/12D3KooWKYAhezQQqwWvQ8iECUv9R5tTy6639s13ZqrS5tp66Hpd)
+Listen addresses: [
+  '/ip4/127.0.0.1/tcp/37097',
+  '/ip4/192.168.1.17/tcp/37097',
+  '/ip4/10.155.221.162/tcp/37097',
+  '/ip4/127.0.0.1/tcp/37941/ws',
+  '/ip4/192.168.1.17/tcp/37941/ws',
+  '/ip4/10.155.221.162/tcp/37941/ws'
+]
+===========================
+```
+
+The identify information includes:
+- Peer ID: The unique identifier of the peer
+- Agent Version: The version of the libp2p implementation and runtime
+- Protocol Version: The version of the identify protocol
+- Supported protocols: List of protocols that the peer supports
+- Observed address: The address that the peer sees you connecting from
+- Listen addresses: All addresses that the peer is listening on
+
+## Need Help?
+
+- Read the [js-libp2p documentation](https://github.com/libp2p/js-libp2p/tree/main/doc)
+- Check out the [js-libp2p API docs](https://libp2p.github.io/js-libp2p/)
+- Ask a question on the [js-libp2p discussion board](https://github.com/libp2p/js-libp2p/discussions) 

examples/js-libp2p-example-identify/package.json

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+{
+  "name": "js-libp2p-example-identify",
+  "version": "1.0.0",
+  "description": "Example of using the identify protocol with js-libp2p",
+  "main": "src/listener.js",
+  "scripts": {
+    "start": "node src/listener.js",
+    "dial": "node src/dialer.js"
+  },
+  "dependencies": {
+    "@chainsafe/libp2p-noise": "^12.0.0",
+    "@chainsafe/libp2p-yamux": "^4.0.0",
+    "@libp2p/identify": "^3.0.0",
+    "@libp2p/mdns": "^8.0.0",
+    "@libp2p/tcp": "^8.0.0",
+    "@libp2p/websockets": "^7.0.0",
+    "@multiformats/multiaddr": "^12.0.0",
+    "libp2p": "^2.0.0"
+  },
+  "engines": {
+    "node": ">=20.0.0"
+  },
+  "type": "module"
+} 

examples/js-libp2p-example-identify/src/dialer.js

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+import { createLibp2p } from 'libp2p'
+import { tcp } from '@libp2p/tcp'
+import { webSockets } from '@libp2p/websockets'
+import { noise } from '@chainsafe/libp2p-noise'
+import { yamux } from '@chainsafe/libp2p-yamux'
+import { mdns } from '@libp2p/mdns'
+import { multiaddr } from '@multiformats/multiaddr'
+import { identify } from '@libp2p/identify'
+
+async function main () {
+  const node = await createLibp2p({
+    addresses: {
+      listen: [
+        '/ip4/0.0.0.0/tcp/0',
+        '/ip4/0.0.0.0/tcp/0/ws'
+      ]
+    },
+    transports: [
+      tcp(),
+      webSockets()
+    ],
+    streamMuxers: [
+      yamux()
+    ],
+    connectionEncrypters: [
+      noise()
+    ],
+    peerDiscovery: [
+      mdns()
+    ],
+    services: {
+      identify: identify()
+    }
+  })
+
+  // Listen for new connections
+  node.addEventListener('connection:open', (evt) => {
+    console.log('New connection opened:', evt.detail.remotePeer.toString())
+  })
+
+  // Listen for identify events
+  node.addEventListener('peer:identify', (evt) => {
+    const { peerId, protocols, observedAddr, agentVersion, protocolVersion, listenAddrs } = evt.detail
+    console.log('\n=== Identify Information ===')
+    console.log('Peer ID:', peerId.toString())
+    console.log('Agent Version:', agentVersion)
+    console.log('Protocol Version:', protocolVersion)
+    console.log('Supported protocols:', protocols)
+    console.log('Observed address:', observedAddr)
+    console.log('Listen addresses:', listenAddrs.map(addr => addr.toString()))
+    console.log('===========================\n')
+  })
+
+  await node.start()
+  console.log('Dialer node started with peer ID:', node.peerId.toString())
+
+  // Get targetMultiaddr from command line arguments
+  const targetMultiaddrStr = process.argv[2]
+
+  if (!targetMultiaddrStr) {
+    console.error('Usage: node dialer.js <targetMultiaddr>')
+    process.exit(1)
+  }
+
+  try {
+    const targetMultiaddr = multiaddr(targetMultiaddrStr)
+    console.log('Dialing to:', targetMultiaddr.toString())
+    await node.dial(targetMultiaddr)
+    console.log('Successfully dialed to target node')
+  } catch (err) {
+    console.error('Failed to dial target node:', err)
+  }
+}
+
+main().catch(console.error) 

examples/js-libp2p-example-identify/src/listener.js

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+import { createLibp2p } from 'libp2p'
+import { tcp } from '@libp2p/tcp'
+import { webSockets } from '@libp2p/websockets'
+import { noise } from '@chainsafe/libp2p-noise'
+import { yamux } from '@chainsafe/libp2p-yamux'
+import { mdns } from '@libp2p/mdns'
+import { identify } from '@libp2p/identify'
+
+async function main () {
+  const node = await createLibp2p({
+    addresses: {
+      listen: [
+        '/ip4/0.0.0.0/tcp/0',
+        '/ip4/0.0.0.0/tcp/0/ws'
+      ]
+    },
+    transports: [
+      tcp(),
+      webSockets()
+    ],
+    streamMuxers: [
+      yamux()
+    ],
+    connectionEncrypters: [
+      noise()
+    ],
+    peerDiscovery: [
+      mdns()
+    ],
+    services: {
+      identify: identify()
+    }
+  })
+
+  // Listen for new connections
+  node.addEventListener('connection:open', (evt) => {
+    console.log('New connection opened:', evt.detail.remotePeer.toString())
+  })
+
+  // Listen for identify events
+  node.addEventListener('peer:identify', (evt) => {
+    const { peerId, protocols, observedAddr, agentVersion, protocolVersion, listenAddrs } = evt.detail
+    console.log('\n=== Identify Information ===')
+    console.log('Peer ID:', peerId.toString())
+    console.log('Agent Version:', agentVersion)
+    console.log('Protocol Version:', protocolVersion)
+    console.log('Supported protocols:', protocols)
+    console.log('Observed address:', observedAddr)
+    console.log('Listen addresses:', listenAddrs.map(addr => addr.toString()))
+    console.log('===========================\n')
+  })
+
+  await node.start()
+  console.log('Listener node started with peer ID:', node.peerId.toString())
+  console.log('Listener multiaddrs:', node.getMultiaddrs().map(addr => addr.toString()).join('\n'))
+}
+
+main().catch(console.error)