Files
py-libp2p/libp2p/discovery/mdns/mdns.py
2025-06-24 14:25:35 +05:30

86 lines
3.1 KiB
Python

"""
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()