fix: prevent duplicate connections to multiaddr

After opening a new connection, check if there is an existing connection
to the same peer. If the existing connection is not limited or the new
connection is also limit, return the existing connection.

This will prevent multiple connections to the same peer in cases where
the multiaddr being dialed does not contain a peer id.

Author: tabcat

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

@@ -135,11 +135,12 @@ export class DialQueue {
    */
   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 @@ export class DialQueue {
               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)