multicast/broadcast support

lib/services/udp_service.dart

@@ -3,6 +3,7 @@ import 'dart:io';
 import 'package:udp/udp.dart';
 
 class UdpService {
+  /// Send a package to a single IP address
   Future<bool> sendPackage({
     required String data,
     required String ipAddress,
@@ -37,6 +38,98 @@ class UdpService {
       sender?.close();
     }
   }
+
+  /// Send a broadcast package to all devices on the network
+  Future<bool> sendBroadcast({
+    required String data,
+    required int port,
+    String broadcastAddress = '255.255.255.255',
+  }) async {
+    UDP? sender;
+    try {
+      // Create UDP instance
+      sender = await UDP.bind(Endpoint.any());
+      
+      // Convert data to bytes
+      final dataBytes = utf8.encode(data);
+      
+      // Parse broadcast address
+      final address = InternetAddress(broadcastAddress);
+      
+      // Create broadcast endpoint - Endpoint.broadcast takes only port
+      final destination = Endpoint.broadcast(port: Port(port));
+      
+      // Send the broadcast packet
+      final bytesSent = await sender.send(dataBytes, destination);
+      
+      // Give a small delay to ensure packet is sent
+      await Future.delayed(const Duration(milliseconds: 100));
+      
+      return bytesSent > 0;
+    } catch (e) {
+      // Error occurred while sending broadcast package
+      return false;
+    } finally {
+      // Always close the socket
+      sender?.close();
+    }
+  }
+
+  /// Send a package to multiple IP addresses
+  /// Returns a map of IP address to success status
+  Future<Map<String, bool>> sendToMultipleIps({
+    required String data,
+    required List<String> ipAddresses,
+    required int port,
+  }) async {
+    final results = <String, bool>{};
+    
+    for (final ip in ipAddresses) {
+      final success = await sendPackage(
+        data: data,
+        ipAddress: ip,
+        port: port,
+      );
+      results[ip] = success;
+    }
+    
+    return results;
+  }
+
+  /// Send a package with support for broadcast mode and multiple IPs
+  /// Returns a map of targets (IP addresses or "broadcast") to success status
+  Future<Map<String, bool>> sendPackageAdvanced({
+    required String data,
+    required int port,
+    bool isBroadcast = false,
+    List<String>? ipAddresses,
+    String broadcastAddress = '255.255.255.255',
+  }) async {
+    if (isBroadcast) {
+      // Send broadcast
+      final success = await sendBroadcast(
+        data: data,
+        port: port,
+        broadcastAddress: broadcastAddress,
+      );
+      return {'broadcast': success};
+    } else if (ipAddresses != null && ipAddresses.isNotEmpty) {
+      // Send to multiple IPs
+      return await sendToMultipleIps(
+        data: data,
+        ipAddresses: ipAddresses,
+        port: port,
+      );
+    } else {
+      // Fallback to localhost
+      final success = await sendPackage(
+        data: data,
+        ipAddress: '127.0.0.1',
+        port: port,
+      );
+      return {'127.0.0.1': success};
+    }
+  }
 }