Add a check if Internet is available

README.md

@@ -13,7 +13,7 @@ dependencies:
 
 #### Note for AndroidX Apps
 
-Make sure to point to `0.2.4+1`
+Make sure to point to `0.2.4+2`
 
 ### ⚡️ Import
 
@@ -35,6 +35,8 @@ class DemoPage extends StatelessWidget {
         title: new Text("Offline Demo"),
       ),
       body: OfflineBuilder(
+        checkHost : true, // check if internet is avaiable by a DNS request , the default value is false
+        // hostToCheck : "my.domaine.name", // the default value is google.com 
         connectivityBuilder: (
           BuildContext context,
           ConnectivityResult connectivity,

lib/src/main.dart

@@ -5,6 +5,7 @@ import 'package:flutter/widgets.dart';
 import 'package:flutter_offline/src/utils.dart';
 
 const kOfflineDebounceDuration = const Duration(seconds: 3);
+const kHostToCheck = 'google.com';
 
 typedef Widget ConnectivityBuilder(
     BuildContext context, ConnectivityResult connectivity, Widget child);
@@ -14,6 +15,8 @@ class OfflineBuilder extends StatefulWidget {
     Key key,
     @required ConnectivityBuilder connectivityBuilder,
     Duration debounceDuration = kOfflineDebounceDuration,
+    String hostToCheck = kHostToCheck,
+    bool checkHost = false,
     WidgetBuilder builder,
     Widget child,
     WidgetBuilder errorBuilder,
@@ -23,6 +26,8 @@ class OfflineBuilder extends StatefulWidget {
       connectivityBuilder: connectivityBuilder,
       connectivityService: Connectivity(),
       debounceDuration: debounceDuration,
+      hostToCheck : hostToCheck,
+      checkHost : checkHost,
       builder: builder,
       child: child,
       errorBuilder: errorBuilder,
@@ -35,12 +40,16 @@ class OfflineBuilder extends StatefulWidget {
     @required this.connectivityBuilder,
     @required this.connectivityService,
     this.debounceDuration = kOfflineDebounceDuration,
+    this.hostToCheck = kHostToCheck,
+    this.checkHost = false,
     this.builder,
     this.child,
     this.errorBuilder,
   })  : assert(
             connectivityBuilder != null, 'connectivityBuilder cannot be null'),
         assert(debounceDuration != null, 'debounceDuration cannot be null'),
+        assert(hostToCheck != null, 'hostToCheck cannot be null'),
+        assert(checkHost != null, 'checkHost cannot be true or false'),
         assert(
             connectivityService != null, 'connectivityService cannot be null'),
         assert(
@@ -55,6 +64,12 @@ class OfflineBuilder extends StatefulWidget {
   /// Debounce duration from epileptic network situations
   final Duration debounceDuration;
 
+  /// Hostname to test internet connection 
+  final String hostToCheck;
+
+  /// hostToCheck to test internet connection 
+  final bool checkHost;
+
   /// Used for building the Offline and/or Online UI
   final ConnectivityBuilder connectivityBuilder;
 
@@ -86,7 +101,11 @@ class OfflineBuilderState extends State<OfflineBuilder> {
           startsWith(data),
         );
       },
-    ).transform(
+    );
+    _connectivityStream = widget.checkHost ? _connectivityStream.transform(
+       checkIfHostIsAvailble(widget.hostToCheck),
+    ) : _connectivityStream;
+     _connectivityStream = _connectivityStream.transform(
       debounce(widget.debounceDuration),
     );
   }

lib/src/utils.dart

@@ -1,4 +1,5 @@
 import 'dart:async';
+import 'dart:io';
 
 import 'package:connectivity/connectivity.dart';
 
@@ -56,3 +57,37 @@ StreamTransformer<ConnectivityResult, ConnectivityResult> startsWith(
     },
   );
 }
+
+StreamTransformer<ConnectivityResult, ConnectivityResult> checkIfHostIsAvailble(
+  String host,
+) {
+  bool _seenFirstData = false;
+  Timer _timer;
+
+  return StreamTransformer<ConnectivityResult, ConnectivityResult>.fromHandlers(
+    handleData: (ConnectivityResult data, EventSink<ConnectivityResult> sink) {
+      if (_seenFirstData) {
+        _timer?.cancel();
+        _timer = Timer(Duration.zero, ()async {
+          try {
+            final result = await InternetAddress.lookup(host);
+            if (result.isNotEmpty && result[0].rawAddress.isNotEmpty) {
+              sink.add(data);
+            }else{
+              sink.add(ConnectivityResult.none);
+            }
+          } on SocketException catch (_) {
+            sink.add(ConnectivityResult.none);
+          }
+        });
+      } else {
+        sink.add(data);
+        _seenFirstData = true;
+      }
+    },
+    handleDone: (EventSink<ConnectivityResult> sink) {
+      _timer?.cancel();
+      sink.close();
+    },
+  );
+}

pubspec.yaml

@@ -1,6 +1,6 @@
 name: flutter_offline
 description: A tidy utility to handle offline/online connectivity like a Boss.
-version: 0.2.4+1
+version: 0.2.4+2
 author: Jeremiah Ogbomo <[email protected]>
 homepage: https://github.com/jogboms/flutter_offline