Fix multi-address listening bug in swarm.listen()

- Fix early return in swarm.listen() that prevented listening on all addresses
- Add comprehensive tests for multi-address listening functionality
- Ensure all available interfaces are properly bound and connectable

libp2p/network/swarm.py

@@ -249,9 +249,11 @@ class Swarm(Service, INetworkService):
         # We need to wait until `self.listener_nursery` is created.
         await self.event_listener_nursery_created.wait()
 
+        success_count = 0
         for maddr in multiaddrs:
             if str(maddr) in self.listeners:
-                return True
+                success_count += 1
+                continue
 
             async def conn_handler(
                 read_write_closer: ReadWriteCloser, maddr: Multiaddr = maddr
@@ -302,13 +304,14 @@ class Swarm(Service, INetworkService):
                 # Call notifiers since event occurred
                 await self.notify_listen(maddr)
 
-                return True
+                success_count += 1
+                logger.debug("successfully started listening on: %s", maddr)
             except OSError:
                 # Failed. Continue looping.
                 logger.debug("fail to listen on: %s", maddr)
 
-        # No maddr succeeded
-        return False
+        # Return true if at least one address succeeded
+        return success_count > 0
 
     async def close(self) -> None:
         """