fix(network_info_plus): Return null for Linux subnet mask and broadcast when IPv4 data is missing

packages/network_info_plus/network_info_plus/example/windows/CMakeLists.txt

@@ -29,6 +29,11 @@ set(CMAKE_CXX_FLAGS_PROFILE "${CMAKE_CXX_FLAGS_RELEASE}")
 # Use Unicode for all projects.
 add_definitions(-DUNICODE -D_UNICODE)
 
+# Newer MSVC (VS 2026) turns the deprecation of <experimental/coroutine> into a
+# hard error. permission_handler_windows still uses it, so silence it for all
+# targets (including plugins) until that package is updated.
+add_definitions(-D_SILENCE_EXPERIMENTAL_COROUTINE_DEPRECATION_WARNINGS)
+
 # Compilation settings that should be applied to most targets.
 function(APPLY_STANDARD_SETTINGS TARGET)
   target_compile_features(${TARGET} PUBLIC cxx_std_17)

packages/network_info_plus/network_info_plus/lib/src/network_info_plus_linux.dart

@@ -96,14 +96,16 @@ class NetworkInfoPlusLinuxPlugin extends NetworkInfoPlatform {
   }
 
   String? _getSubnetMask(List<Map<String, dynamic>>? data) {
-    final prefix = data?.firstOrNull?['prefix'] as int;
+    final prefix = data?.firstOrNull?['prefix'] as int?;
+    if (prefix == null) return null;
     final mask = (0xffffffff << (32 - prefix)) & 0xffffffff;
     return mask.toIpString();
   }
 
   String? _getBroadcast(List<Map<String, dynamic>>? data) {
-    final ip = _getIpAddress(data)?.toIpInt() ?? 0;
-    final mask = _getSubnetMask(data)?.toIpInt() ?? 0;
+    final ip = _getIpAddress(data)?.toIpInt();
+    final mask = _getSubnetMask(data)?.toIpInt();
+    if (ip == null || mask == null) return null;
     return (ip | (mask ^ 0xffffffff)).toIpString();
   }
 

packages/network_info_plus/network_info_plus/test/network_info_plus_linux_test.dart

@@ -26,7 +26,7 @@ void main() {
     for (final (address, prefix, mask, broadcast) in cases) {
       test('$address/$prefix', () async {
         final plugin = NetworkInfoPlusLinuxPlugin()
-          ..createClient = () => _FakeClient(address: address, prefix: prefix);
+          ..createClient = () => _FakeClient.withAddress(address, prefix);
 
         expect(await plugin.getWifiSubmask(), mask);
         expect(await plugin.getWifiBroadcast(), broadcast);
@@ -36,15 +36,36 @@ void main() {
 
   test('wifi IP and gateway are passed through', () async {
     final plugin = NetworkInfoPlusLinuxPlugin()
-      ..createClient = () => _FakeClient(address: '192.168.1.10', prefix: 22);
+      ..createClient = () => _FakeClient.withAddress('192.168.1.10', 22);
 
     expect(await plugin.getWifiIP(), '192.168.1.10');
     expect(await plugin.getWifiGatewayIP(), '192.168.0.1');
   });
+
+  group('missing IPv4 data returns null', () {
+    final cases = <String, NetworkManagerActiveConnection? Function()>{
+      'primaryConnection is null': () => null,
+      'ip4Config is null': () => _FakeConnection(null),
+      'addressData is empty': () => _FakeConnection(_FakeIp4Config([])),
+    };
+
+    for (final MapEntry(key: description, value: connection) in cases.entries) {
+      test(description, () async {
+        final plugin = NetworkInfoPlusLinuxPlugin()
+          ..createClient = () => _FakeClient(connection());
+
+        expect(await plugin.getWifiSubmask(), isNull);
+        expect(await plugin.getWifiBroadcast(), isNull);
+        expect(await plugin.getWifiIP(), isNull);
+      });
+    }
+  });
 }
 
 class _FakeClient extends Fake implements NetworkManagerClient {
-  _FakeClient({required String address, required int prefix})
+  _FakeClient(this.primaryConnection);
+
+  _FakeClient.withAddress(String address, int prefix)
     : primaryConnection = _FakeConnection(
         _FakeIp4Config([
           {'address': address, 'prefix': prefix},