feat: implement broadcasting in mdns

libp2p/discovery/mdns/broadcaster.py

@@ -0,0 +1,49 @@
+from zeroconf import Zeroconf, ServiceInfo
+from .utils import stringGen
+import socket
+
+class PeerBroadcaster:
+    """
+    Broadcasts this peer's presence on the local network using mDNS/zeroconf.
+    Registers a service with the peer's ID in the TXT record as per libp2p spec.
+    """
+    def __init__(self, zeroconf: Zeroconf, service_type: str, service_name: str, peer_id: str, port: int):
+        self.zeroconf = zeroconf
+        self.service_type = service_type
+        self.peer_id = peer_id
+        self.port = port
+        self.service_name = service_name
+        
+        # Get the local IP address
+        local_ip = self._get_local_ip()
+        
+        self.service_info = ServiceInfo(
+            type_=self.service_type,
+            name=self.service_name,
+            port=self.port,
+            properties={b'id': self.peer_id.encode()},
+            server=f"{self.service_name}",
+            addresses=[socket.inet_aton(local_ip)]
+        )
+
+    def _get_local_ip(self):
+        """Get the local IP address of this machine"""
+        try:
+            # Connect to a remote address to determine the local IP
+            # This doesn't actually send data
+            with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
+                s.connect(("8.8.8.8", 80))
+                local_ip = s.getsockname()[0]
+            return local_ip
+        except Exception:
+            # Fallback to localhost if we can't determine the IP
+            return "127.0.0.1"
+
+    def register(self):
+        """Register the peer's mDNS service on the network."""
+        print(f"Registering with name {self.service_name} and peer_id {self.peer_id} on port {self.port}")
+        self.zeroconf.register_service(self.service_info)
+
+    def unregister(self):
+        """Unregister the peer's mDNS service from the network."""
+        self.zeroconf.unregister_service(self.service_info)