expetion error

loc_chain_app/lib/main.dart

@@ -1,21 +1,22 @@
 import 'package:flutter/material.dart';
+import 'package:loc_chain_app/util/bluetooth.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 import 'package:loc_chain_app/widgets/navbar.dart';
-import 'dart:math';
+import 'package:flutter_udid/flutter_udid.dart';
 
 void main() async {
   runApp(App());
-  final prefs = await SharedPreferences.getInstance();
-  final userName = prefs.getString('userName') ?? '0';
-  if (userName == '0') {
-    prefs.setString('id', Random().nextInt(10000).toString());
-  }
+  (await SharedPreferences.getInstance())
+      .setString('userName', await FlutterUdid.consistentUdid);
 }
 
 class App extends StatelessWidget {
   // This widget is the root of your application.
   @override
   Widget build(BuildContext context) {
+    Connect.stop();
+    Connect.start();
+
     return MaterialApp(
       title: 'Flutter Demo',
       theme: ThemeData(

loc_chain_app/lib/pages/bluetooth.dart

@@ -4,6 +4,7 @@ import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
 import 'package:nearby_connections/nearby_connections.dart';
+import 'package:flutter_udid/flutter_udid.dart';
 
 import 'package:shared_preferences/shared_preferences.dart';
 
@@ -16,7 +17,7 @@ class BluetoothPage extends StatefulWidget {
 }
 
 class _BluetoothPageState extends State<BluetoothPage> {
-  // final String id = getId();
+  final Future<String> _id = FlutterUdid.consistentUdid;
   // String getId() =>
   //     SharedPreferences.getInstance().then((s) => s.getString('id') ?? '0');
 
@@ -26,18 +27,21 @@ class _BluetoothPageState extends State<BluetoothPage> {
       appBar: AppBar(
         title: Text(widget.title),
       ),
-      body: Center(
-        child: ElevatedButton(
-          child: Text("GetID"),
-          onPressed: () async {
-            final prefs = await SharedPreferences.getInstance();
-            final userName = prefs.getString('userName');
-
-            ScaffoldMessenger.of(context)
-                .showSnackBar(SnackBar(content: Text("Id is $userName")));
-          },
-        ),
-      ),
+      body: FutureBuilder<String>(
+          future: _id, // a previously-obtained Future<String> or null
+          builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
+            String content = "Loading id...";
+            if (snapshot.hasData) {
+              content = "ID: ${snapshot.data!}";
+            }
+            return ListView(
+              children: <Widget>[
+                Container(
+                  child: Text(content),
+                ),
+              ],
+            );
+          }),
     );
   }
 

loc_chain_app/lib/pages/home.dart

@@ -1,4 +1,7 @@
 import 'package:flutter/material.dart';
+import 'package:flutter_udid/flutter_udid.dart';
+import 'package:loc_chain_app/util/bluetooth.dart';
+import 'package:loc_chain_app/util/transaction_manager.dart';
 
 class HomePage extends StatefulWidget {
   HomePage({Key? key, required this.title}) : super(key: key);
@@ -9,16 +12,16 @@ class HomePage extends StatefulWidget {
 }
 
 class _HomePageState extends State<HomePage> {
-  int _counter = 0;
+  final Future<String> _id = FlutterUdid.consistentUdid;
+  Connect connector = Connect();
+  Map<String, Transaction> transactionMap = Map();
+  // String getId() =>
+  //     SharedPreferences.getInstance().then((s) => s.getString('id') ?? '0');
 
-  void _incrementCounter() {
+  void refreshTransactions() {
     setState(() {
-      // This call to setState tells the Flutter framework that something has
-      // changed in this State, which causes it to rerun the build method below
-      // so that the display can reflect the updated values. If we changed
-      // _counter without calling setState(), then the build method would not be
-      // called again, and so nothing would appear to happen.
-      _counter++;
+      transactionMap = Connect.transactionMap;
+      Connect.context = context;
     });
   }
 
@@ -28,25 +31,51 @@ class _HomePageState extends State<HomePage> {
       appBar: AppBar(
         title: Text(widget.title),
       ),
-      body: Center(
-        child: Column(
-          mainAxisAlignment: MainAxisAlignment.center,
-          children: <Widget>[
-            Text(
-              'You have pushed the button this many times:',
-            ),
-            Text(
-              '$_counter',
-              style: Theme.of(context).textTheme.headline4,
-            ),
-          ],
-        ),
-      ),
+      body: FutureBuilder<String>(
+          future: _id, // a previously-obtained Future<String> or null
+          builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
+            String content = "Loading id...";
+            if (snapshot.hasData) {
+              content = "ID: ${snapshot.data!}";
+            }
+            List<Card> transactions = List.generate(
+              transactionMap.length,
+              (index) {
+                Transaction t = transactionMap.values.elementAt(index);
+                return Card(
+                  child: Row(
+                    children: [Text(t.hash), Text(t.pubKey)],
+                  ),
+                );
+              },
+            );
+            return ListView(
+              children: <Widget>[
+                    Container(
+                      child: Text(content),
+                    ),
+                  ] +
+                  transactions,
+            );
+          }),
       floatingActionButton: FloatingActionButton(
-        onPressed: _incrementCounter,
-        tooltip: 'Increment',
-        child: Icon(Icons.add),
+        onPressed: () {
+          refreshTransactions();
+          try {
+            Connect.stop();
+            Connect.start();
+          } catch (e) {
+            print(e);
+          }
+        },
+        child: Icon(Icons.refresh_sharp),
       ),
     );
   }
+
+  void showSnackbar(dynamic a) {
+    ScaffoldMessenger.of(context).showSnackBar(SnackBar(
+      content: Text(a.toString()),
+    ));
+  }
 }

loc_chain_app/lib/util/bluetooth.dart

@@ -1,8 +1,7 @@
-import 'dart:io';
-import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:flutter/material.dart';
+import 'package:flutter_udid/flutter_udid.dart';
 import 'package:nearby_connections/nearby_connections.dart';
 
 import 'package:shared_preferences/shared_preferences.dart';
@@ -11,20 +10,15 @@ import 'package:loc_chain_app/util/keyfile_manager.dart';
 import 'package:loc_chain_app/util/transaction_manager.dart';
 
 class Connect {
-  final serviceId = "com.yourdomain.appname";
-  final Strategy strategy = Strategy.P2P_STAR;
-  late final _userName;
-  final BuildContext? context;
+  static final serviceId = "com.yourdomain.appname";
+  static final Strategy strategy = Strategy.P2P_STAR;
+  static String _userName = "";
+  static BuildContext? context;
 
-  Map<String, ConnectionInfo> endpointMap = Map();
-  Map<String, Transaction> transactionMap = Map();
+  static Map<String, ConnectionInfo> endpointMap = Map();
+  static Map<String, Transaction> transactionMap = Map();
 
-  Connect({this.context}) {
-    SharedPreferences.getInstance()
-        .then((s) => _userName = s.getString('userName') ?? '0');
-  }
-
-  void showSnackbar(dynamic a) {
+  static void showSnackbar(dynamic a) {
     if (context == null) {
       return;
     }
@@ -33,78 +27,100 @@ class Connect {
     ));
   }
 
-  void startConnect() async {
+  static void stop() {
+    Nearby().stopAdvertising();
+    Nearby().stopDiscovery();
+    Nearby().stopAllEndpoints();
+  }
+
+  static void start() async {
+    _userName = await FlutterUdid.consistentUdid;
     // final prefs = await SharedPreferences.getInstance();
     // final userName = prefs.getString('userName') ?? " ";
 
-    try {
-      bool advertise = await Nearby().startAdvertising(
-        _userName,
-        strategy,
-        onConnectionInitiated: onConnectionInit,
-        onConnectionResult: (String id, Status status) async {
-          // Called when connection is accepted/rejected
-          // if connection is accepted send the transaction
-          if (status != Status.CONNECTED) {
-            return;
-          }
-          // Connected to other device, send combined hash and pub key
-          String str = await Transaction.generateHash(id);
-          Nearby().sendBytesPayload(id, Uint8List.fromList(str.codeUnits));
-        },
-        onDisconnected: (String id) {
-          // Callled whenever a discoverer disconnects from advertiser
-          // delete connection info
-          endpointMap.remove(id);
-          // delete transaction info
-          transactionMap.remove(id);
-        },
-        serviceId: serviceId, // uniquely identifies your app
-      );
-
-      bool discovery = await Nearby().startDiscovery(
-        _userName,
-        strategy,
-        onEndpointFound: (String id, String userName, String serviceId) {
-          // called when an advertiser is found
-          Nearby().requestConnection(
-            userName,
-            id,
-            onConnectionInitiated: onConnectionInit,
-            onConnectionResult: (String id, Status status) async {
-              // Called when connection is accepted/rejected
-              // if connection is accepted send the transaction
-              if (status != Status.CONNECTED) {
-                return;
-              }
-              // Connected to other device, send combined hash and pub key
-              String str = await Transaction.generateHash(id);
-              Nearby().sendBytesPayload(id, Uint8List.fromList(str.codeUnits));
-            },
-            onDisconnected: (id) {
-              endpointMap.remove(id);
-              showSnackbar(
-                  "Disconnected from: ${endpointMap[id]!.endpointName}, id $id");
-            },
-          );
-        },
-        onEndpointLost: (String? id) {
-          //called when an advertiser is lost (only if we weren't connected to it )
-        },
-        serviceId: serviceId, // uniquely identifies your app
-      );
-    } catch (exception) {
-      // platform exceptions like unable to start bluetooth or insufficient permissions
-    }
+    Nearby().startAdvertising(
+      _userName,
+      strategy,
+      onConnectionInitiated: onConnectionInit,
+      onConnectionResult: (String id, Status status) async {
+        // Called when connection is accepted/rejected
+        // if connection is accepted send the transaction
+        if (status != Status.CONNECTED) {
+          return;
+        }
+        // Connected to other device, send combined hash and pub key
+        String str = await Transaction.generateHash(id);
+        print(str);
+        Nearby().sendBytesPayload(id, Uint8List.fromList(str.codeUnits));
+      },
+      onDisconnected: (String id) {
+        // Callled whenever a discoverer disconnects from advertiser
+        // delete connection info
+        endpointMap.remove(id);
+        // delete transaction info
+        transactionMap.remove(id);
+      },
+      serviceId: serviceId, // uniquely identifies your app
+    ).catchError((e) {
+      print(e);
+      return true;
+    });
+
+    Nearby().startDiscovery(
+      _userName,
+      strategy,
+      onEndpointFound: (String id, String userName, String serviceId) {
+        // called when an advertiser is found
+        Nearby().requestConnection(
+          userName,
+          id,
+          onConnectionInitiated: onConnectionInit,
+          onConnectionResult: (String id, Status status) async {
+            // Called when connection is accepted/rejected
+            // if connection is accepted send the transaction
+            if (status != Status.CONNECTED) {
+              return;
+            }
+            // Connected to other device, send combined hash and pub key
+            String str = await Transaction.generateHash(id);
+            Nearby()
+                .sendBytesPayload(id, Uint8List.fromList(str.codeUnits))
+                .catchError((e) {
+              print(e);
+            });
+          },
+          onDisconnected: (id) {
+            endpointMap.remove(id);
+            print(
+                "Disconnected from: ${endpointMap[id]!.endpointName}, id $id");
+          },
+        ).catchError((e) {
+          print(e);
+          return true;
+        });
+      },
+      onEndpointLost: (String? id) {
+        //called when an advertiser is lost (only if we weren't connected to it )
+      },
+      serviceId: serviceId, // uniquely identifies your app
+    ).catchError((e) {
+      print(e);
+      return true;
+    });
   }
 
-  void onConnectionInit(String otherId, ConnectionInfo info) {
+  static void onConnectionInit(String otherId, ConnectionInfo info) {
+    print('Connection initialized with $otherId');
     // Called whenever a discoverer requests connection
     //
     // onConnectionInit
     if (endpointMap.containsKey(otherId)) {
+      print('Connection rejected to/from $otherId');
       Nearby().rejectConnection(otherId);
+      return;
     }
+    print('Connection accepted to/from $otherId');
+
     endpointMap[otherId] = info;
     Nearby().acceptConnection(
       otherId,
@@ -114,7 +130,7 @@ class Connect {
         String str = String.fromCharCodes(payload.bytes!);
         var parts = str.split(':');
         if (parts.length != 2) {
-          showSnackbar("$_otherId invalid payload: $str");
+          print("$_otherId invalid payload: $str");
           return;
         }
         // Store transaction
@@ -123,7 +139,6 @@ class Connect {
         transactionMap[_otherId] =
             Transaction(hash: combinedHash, pubKey: publicKey);
         // sign combined hash with our private key
-        showSnackbar('Received $_otherId payload: $combinedHash');
         print('Received $_otherId payload: $combinedHash:$publicKey');
         // upload hash+otherKey to firebase
       },
@@ -131,14 +146,16 @@ class Connect {
         if (payloadTransferUpdate.status == PayloadStatus.IN_PROGRESS) {
           print(payloadTransferUpdate.bytesTransferred);
         } else if (payloadTransferUpdate.status == PayloadStatus.FAILURE) {
-          print("failed");
-          showSnackbar(endid + ": FAILED to transfer file");
+          print(endid + ": FAILED to transfer file");
         } else if (payloadTransferUpdate.status == PayloadStatus.SUCCESS) {
-          showSnackbar(
+          print(
               "$endid success, total bytes = ${payloadTransferUpdate.totalBytes}");
         }
       },
-    );
+    ).catchError((e) {
+      print(e);
+      return true;
+    });
   }
 }
 

loc_chain_app/pubspec.lock

@@ -43,6 +43,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "1.15.0"
+  crypto:
+    dependency: transitive
+    description:
+      name: crypto
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "3.0.1"
   cupertino_icons:
     dependency: "direct main"
     description:
@@ -102,6 +109,13 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_udid:
+    dependency: "direct main"
+    description:
+      name: flutter_udid
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "2.0.0"
   flutter_web_plugins:
     dependency: transitive
     description: flutter
@@ -345,4 +359,4 @@ packages:
     version: "0.2.0"
 sdks:
   dart: ">=2.12.0 <3.0.0"
-  flutter: ">=1.24.0-10"
+  flutter: ">=2.0.0"

loc_chain_app/pubspec.yaml

@@ -33,6 +33,7 @@ dependencies:
   fast_rsa: ^1.4.0-nullsafety.4
   sqflite: ^2.0.0+3
   dbcrypt: ^2.0.0
+  flutter_udid: ^2.0.0
 
 dev_dependencies:
   flutter_test: