fix: prevent duplicate connections to multiaddr

packages/libp2p/src/connection-manager/dial-queue.ts

@@ -135,11 +135,12 @@
    */
   async dial (peerIdOrMultiaddr: PeerId | Multiaddr | Multiaddr[], options: OpenConnectionOptions = {}): Promise<Connection> {
     const { peerId, multiaddrs } = getPeerAddress(peerIdOrMultiaddr)
+    const { force } = options
 
     // make sure we don't have an existing connection to any of the addresses we
     // are about to dial
     const existingConnection = Array.from(this.connections.values()).flat().find(conn => {
-      if (options.force === true) {
+      if (force === true) {
         return false
       }
 
@@ -260,6 +261,30 @@
               this.log.error('could not update last dial failure key for %p', peerId, err)
             }
 
+            const { remotePeer } = conn
+
+            // make sure we don't have an existing connection to the address we dialed
+            const existingConnection = Array.from(this.connections.values()).flat().find(_conn => {
+              if (force === true) {
+                return false
+              }
+
+              if (_conn.remotePeer.equals(remotePeer) && _conn !== conn) {
+                return true
+              }
+
+              return false
+            })
+
+            // return existing, open connection to peer if equal or better limits
+            if (existingConnection?.status === 'open' && (existingConnection?.limits == null || conn?.limits != null)) {
+              this.log('already connected to %a', existingConnection.remoteAddr)
+              options?.onProgress?.(new CustomProgressEvent('dial-queue:already-connected'))
+              this.log('closing duplicate connection to %p', remotePeer)
+              await conn.close()
+              return existingConnection
+            }
+
             return conn
           } catch (err: any) {
             this.log.error('dial failed to %a', address.multiaddr, err)

packages/libp2p/test/connection-manager/dial-queue.spec.ts

@@ -5,6 +5,7 @@ import { NotFoundError } from '@libp2p/interface'
 import { matchMultiaddr } from '@libp2p/interface-compliance-tests/matchers'
 import { mockConnection, mockDuplex, mockMultiaddrConnection } from '@libp2p/interface-compliance-tests/mocks'
 import { peerLogger } from '@libp2p/logger'
+import { PeerMap } from '@libp2p/peer-collections'
 import { peerIdFromPrivateKey } from '@libp2p/peer-id'
 import { multiaddr, resolvers } from '@multiformats/multiaddr'
 import { WebRTC } from '@multiformats/multiaddr-matcher'
@@ -325,4 +326,74 @@ describe('dial queue', () => {
     dialer = new DialQueue(components)
     await expect(dialer.dial(remotePeer)).to.eventually.equal(connection)
   })
+
+  it('should return existing connection when dialing a multiaddr without a peer id', async () => {
+    const remotePeer = peerIdFromPrivateKey(await generateKeyPair('Ed25519'))
+    const ip = multiaddr('/ip4/123.123.123.123')
+    const addr1 = ip.encapsulate('/tcp/123')
+    const addr2 = ip.encapsulate('/tcp/321')
+
+    const existingConnection = stubInterface<Connection>({
+      limits: {
+        bytes: 100n
+      },
+      remotePeer,
+      remoteAddr: addr1.encapsulate(`/p2p/${remotePeer}`),
+      status: 'open'
+    })
+
+    const newConnection = stubInterface<Connection>({
+      limits: {
+        bytes: 100n
+      },
+      remotePeer,
+      remoteAddr: addr2.encapsulate(`/p2p/${remotePeer}`),
+      status: 'open'
+    })
+
+    const connections = new PeerMap<Connection[]>()
+    connections.set(remotePeer, [existingConnection])
+
+    components.transportManager.dialTransportForMultiaddr.callsFake(ma => {
+      return stubInterface<Transport>()
+    })
+    components.transportManager.dial.callsFake(async (ma, opts = {}) => newConnection)
+    dialer = new DialQueue(components, { connections })
+
+    await expect(dialer.dial(addr2)).to.eventually.equal(existingConnection)
+  })
+
+  it('should return new connection when existing connection to same peer is worse', async () => {
+    const remotePeer = peerIdFromPrivateKey(await generateKeyPair('Ed25519'))
+    const ip = multiaddr('/ip4/123.123.123.123')
+    const addr1 = ip.encapsulate('/tcp/123')
+    const addr2 = ip.encapsulate('/tcp/321')
+
+    const existingConnection = stubInterface<Connection>({
+      limits: {
+        bytes: 100n
+      },
+      remotePeer,
+      remoteAddr: addr1.encapsulate(`/p2p/${remotePeer}`),
+      status: 'open'
+    })
+
+    const newConnection = stubInterface<Connection>({
+      limits: undefined,
+      remotePeer,
+      remoteAddr: addr2.encapsulate(`/p2p/${remotePeer}`),
+      status: 'open'
+    })
+
+    const connections = new PeerMap<Connection[]>()
+    connections.set(remotePeer, [existingConnection])
+
+    components.transportManager.dialTransportForMultiaddr.callsFake(ma => {
+      return stubInterface<Transport>()
+    })
+    components.transportManager.dial.callsFake(async (ma, opts = {}) => newConnection)
+    dialer = new DialQueue(components, { connections })
+
+    await expect(dialer.dial(addr2)).to.eventually.equal(newConnection)
+  })
 })