feat: init mDNS discovery module

libp2p/discovery/mdns/mdns.py

@@ -0,0 +1,85 @@
+"""
+mDNS-based peer discovery for py-libp2p.
+Conforms to https://github.com/libp2p/specs/blob/master/discovery/mdns.md
+Uses zeroconf for mDNS broadcast/listen. Async operations use trio.
+"""
+import trio
+from typing import Callable, Optional
+from zeroconf import ServiceInfo, Zeroconf, ServiceBrowser, ServiceStateChange
+from .utils import (
+    stringGen
+)
+from libp2p.abc import (
+    INetworkService
+)
+
+SERVICE_TYPE = "_p2p._udp.local."
+MCAST_PORT = 5353
+MCAST_ADDR = "224.0.0.251"
+
+class MDNSDiscovery:
+    def __init__(self, swarm: INetworkService):
+        self.peer_id = swarm.get_peer_id()
+        self.port = 8000  # Default port, can be overridden
+        # self.broadcast = init.get('broadcast', True) is not False
+        # self.on_peer = on_peer  # Callback: async def on_peer(peer_info)
+        # self.service_name = service_name or f"{peer_id}.{SERVICE_TYPE}"
+        # self.zeroconf = Zeroconf()
+        # self._service_info = ServiceInfo(
+        #     SERVICE_TYPE,
+        #     self.service_name,
+        #     addresses=[],  # Will be set on register
+        #     port=self.port,
+        #     properties={b'id': peer_id.encode()},
+        # )
+        # self._browser = None
+        # self._running = False
+
+    def main(self) -> None:
+        """
+        Main entry point for the mDNS discovery service.
+        This method is intended to be run in an event loop.
+        """
+        trio.run(self.start)
+
+    async def start(self):
+        await trio.sleep(10)
+        # self._running = True
+        # await trio.to_thread.run_sync(self.zeroconf.register_service, self._service_info)
+        # self._browser = ServiceBrowser(self.zeroconf, SERVICE_TYPE, handlers=[self._on_service_state_change])
+        print(f"Starting mDNS discovery for peer {self.peer_id} on port {self.port}")
+
+    async def stop(self):
+        # self._running = False
+        # await trio.to_thread.run_sync(self.zeroconf.unregister_service, self._service_info)
+        # await trio.to_thread.run_sync(self.zeroconf.close)
+        print(f"Stopping mDNS discovery for peer {self.peer_id}")
+
+    def _on_service_state_change(self, zeroconf, service_type, name, state_change):
+        if state_change is not ServiceStateChange.Added:
+            return
+        info = zeroconf.get_service_info(service_type, name)
+        if not info or name == self.service_name:
+            return
+        peer_id = info.properties.get(b'id')
+        if not peer_id:
+            return
+        peer_id = peer_id.decode()
+        addresses = [addr for addr in info.parsed_addresses()]
+        port = info.port
+        peer_info = {'peer_id': peer_id, 'addresses': addresses, 'port': port}
+        if self.on_peer:
+            # Schedule callback in the background
+            trio.lowlevel.spawn_system_task(self._call_on_peer, peer_info)
+
+    async def _call_on_peer(self, peer_info):
+        if self.on_peer:
+            await self.on_peer(peer_info)
+
+# Example usage:
+# async def on_peer(peer_info):
+#     print(f"Discovered peer: {peer_info['peer_id']} at {peer_info['addresses']}:{peer_info['port']}")
+# mdns = MDNSDiscovery(peer_id, port, on_peer)
+# await mdns.start()
+# ...
+# await mdns.stop()