Add admin_peer RPC endpoint (#3570)

* add initial implementation of admin_peers

* add more fields

* fix versions

* add test

packages/client/src/rpc/modules/admin.ts

@@ -6,6 +6,7 @@ import { middleware } from '../validation.js'
 
 import type { Chain } from '../../blockchain/index.js'
 import type { EthereumClient } from '../../client.js'
+import type { RlpxPeer } from '../../net/peer/rlpxpeer.js'
 import type { Service } from '../../service/index.js'
 
 /**
@@ -28,14 +29,14 @@ export class Admin {
     this._rpcDebug = rpcDebug
 
     this.nodeInfo = middleware(callWithStackTrace(this.nodeInfo.bind(this), this._rpcDebug), 0, [])
+    this.peers = middleware(callWithStackTrace(this.peers.bind(this), this._rpcDebug), 0, [])
   }
 
   /**
    * Returns information about the currently running node.
-   * see for reference: https://geth.ethereum.org/docs/rpc/ns-admin#admin_nodeinfo
-   * @param params An empty array
+   * see for reference: https://geth.ethereum.org/docs/interacting-with-geth/rpc/ns-admin#admin_peers
    */
-  async nodeInfo(_params: []) {
+  async nodeInfo() {
     const rlpxInfo = this._client.config.server!.getRlpxInfo()
     const { enode, id, ip, listenAddr, ports } = rlpxInfo
     const { discovery, listener } = ports
@@ -68,4 +69,34 @@ export class Admin {
     }
     return nodeInfo
   }
+
+  /**
+   * Returns information about currently connected peers
+   * @returns an array of objects containing information about peers (including id, eth protocol versions supported, client name, etc.)
+   */
+  async peers() {
+    const peers = this._client.services.filter((serv) => serv.name === 'eth')[0]?.pool
+      .peers as RlpxPeer[]
+
+    return peers?.map((peer) => {
+      return {
+        id: peer.id,
+        // Typescript complains about the typing of `_hello` if we make rlpxPeer possibly null
+        name: (peer.rlpxPeer as any)['_hello'].clientId ?? null,
+        protocols: {
+          eth: {
+            head: peer.eth?.updatedBestHeader
+              ? bytesToHex(peer.eth.updatedBestHeader?.hash())
+              : bytesToHex(peer.eth?.status.bestHash),
+            difficulty: peer.eth?.status.td.toString(10),
+            version: peer.eth?.['versions'].slice(-1)[0] ?? null,
+          },
+        },
+        caps: peer.eth?.['versions'].map((ver) => 'eth/' + ver),
+        network: {
+          remoteAddress: peer.address,
+        },
+      }
+    })
+  }
 }

packages/client/test/rpc/admin/peers.spec.ts

@@ -0,0 +1,38 @@
+import { randomBytes } from 'crypto'
+import { assert, describe, it } from 'vitest'
+
+import { createClient, createManager, getRpcClient, startRPC } from '../helpers.js'
+
+const method = 'admin_peers'
+
+describe(method, () => {
+  it('works', async () => {
+    const manager = createManager(await createClient({ opened: true, noPeers: true }))
+    const rpc = getRpcClient(startRPC(manager.getMethods()))
+
+    console.log(manager['_client'].services[0].pool)
+    //@ts-ignore
+    manager['_client'].services[0].pool.peers = [
+      {
+        id: 'abcd',
+        eth: {
+          versions: ['68'],
+          status: {
+            td: 1n,
+            bestHash: randomBytes(32),
+          },
+        },
+        rlpxPeer: {
+          _hello: {
+            clientId: 'fakeClient',
+          },
+        },
+        address: '127.0.0.1:8545',
+      },
+    ]
+    const res = await rpc.request(method, [])
+    const { result } = res
+    console.log(res)
+    assert.notEqual(result, undefined, 'admin_peers returns a value')
+  })
+})