[flutter_tools]web]Add support for --csp mode to build web (#48319)

packages/flutter_tools/lib/src/build_runner/web_fs.dart

@@ -150,7 +150,14 @@ class WebFs {
   /// Recompile the web application and return whether this was successful.
   Future<bool> recompile() async {
     if (!_useBuildRunner) {
-      await buildWeb(_flutterProject, _target, _buildInfo, _initializePlatform, _dartDefines);
+      await buildWeb(
+        _flutterProject,
+        _target,
+        _buildInfo,
+        _initializePlatform,
+        _dartDefines,
+        false,
+      );
       return true;
     }
     _client.startBuild();
@@ -309,7 +316,14 @@ class WebFs {
         handler = pipeline.addHandler(proxyHandler('http://localhost:$daemonAssetPort/web/'));
       }
     } else {
-      await buildWeb(flutterProject, target, buildInfo, initializePlatform, dartDefines);
+      await buildWeb(
+        flutterProject,
+        target,
+        buildInfo,
+        initializePlatform,
+        dartDefines,
+        false,
+      );
       firstBuildCompleter.complete(true);
     }
 

packages/flutter_tools/lib/src/build_system/targets/web.dart

@@ -26,6 +26,9 @@ const String kHasWebPlugins = 'HasWebPlugins';
 /// Valid values are O1 (lowest, profile default) to O4 (highest, release default).
 const String kDart2jsOptimization = 'Dart2jsOptimization';
 
+/// Whether to disable dynamic generation code to satisfy csp policies.
+const String kCspMode = 'cspMode';
+
 /// Generates an entry point for a web target.
 class WebEntrypointTarget extends Target {
   const WebEntrypointTarget();
@@ -146,6 +149,7 @@ class Dart2JSTarget extends Target {
   @override
   Future<void> build(Environment environment) async {
     final String dart2jsOptimization = environment.defines[kDart2jsOptimization];
+    final bool csp = environment.defines[kCspMode] == 'true';
     final BuildMode buildMode = getBuildModeForName(environment.defines[kBuildMode]);
     final String specPath = globals.fs.path.join(globals.artifacts.getArtifactPath(Artifact.flutterWebSdk), 'libraries.json');
     final String packageFile = FlutterProject.fromDirectory(environment.projectDir).hasBuilders
@@ -170,6 +174,8 @@ class Dart2JSTarget extends Target {
         '-Ddart.vm.profile=true'
       else
         '-Ddart.vm.product=true',
+      if (csp)
+        '--csp',
       for (final String dartDefine in parseDartDefines(environment))
         '-D$dartDefine',
       environment.buildDir.childFile('main.dart').path,

packages/flutter_tools/lib/src/commands/build_web.dart

@@ -25,6 +25,12 @@ class BuildWebCommand extends BuildSubCommand {
         hide: true,
         help: 'Whether to automatically invoke webOnlyInitializePlatform.',
     );
+    argParser.addFlag('csp',
+      defaultsTo: false,
+      negatable: false,
+      help: 'Disable dynamic generation of code in the generated output.'
+        'This is necessary to satisfy CSP restrictions (see http://www.w3.org/TR/CSP/).'
+    );
   }
 
   @override
@@ -59,6 +65,7 @@ class BuildWebCommand extends BuildSubCommand {
       buildInfo,
       boolArg('web-initialize-platform'),
       dartDefines,
+      boolArg('csp')
     );
     return null;
   }

packages/flutter_tools/lib/src/web/compile.dart

@@ -28,6 +28,7 @@ Future<void> buildWeb(
   BuildInfo buildInfo,
   bool initializePlatform,
   List<String> dartDefines,
+  bool csp,
 ) async {
   if (!flutterProject.web.existsSync()) {
     throwToolExit('Missing index.html.');
@@ -50,6 +51,7 @@ Future<void> buildWeb(
         kInitializePlatform: initializePlatform.toString(),
         kHasWebPlugins: hasWebPlugins.toString(),
         kDartDefines: jsonEncode(dartDefines),
+        kCspMode: csp.toString(),
       },
     ));
     if (!result.success) {

packages/flutter_tools/test/commands.shard/hermetic/build_web_test.dart

@@ -59,6 +59,7 @@ void main() {
       BuildInfo.debug,
       false,
       const <String>[],
+      false,
     ), throwsA(isInstanceOf<ToolExit>()));
   }));
 

packages/flutter_tools/test/general.shard/build_system/targets/web_test.dart

@@ -165,6 +165,33 @@ void main() {
     expect(generated, contains('entrypoint.main();'));
   }));
 
+  test('Dart2JSTarget calls dart2js with expected args with csp', () => testbed.run(() async {
+    environment.defines[kBuildMode] = 'profile';
+    environment.defines[kCspMode] = 'true';
+    when(globals.processManager.run(any)).thenAnswer((Invocation invocation) async {
+      return FakeProcessResult(exitCode: 0);
+    });
+    await const Dart2JSTarget().build(environment);
+
+    final List<String> expected = <String>[
+      globals.fs.path.join('bin', 'cache', 'dart-sdk', 'bin', 'dart'),
+      globals.fs.path.join('bin', 'cache', 'dart-sdk', 'bin', 'snapshots', 'dart2js.dart.snapshot'),
+      '--libraries-spec=' + globals.fs.path.join('bin', 'cache', 'flutter_web_sdk', 'libraries.json'),
+      '-O4', // highest optimizations
+      '--no-minify', // but uses unminified names for debugging
+      '-o',
+      environment.buildDir.childFile('main.dart.js').absolute.path,
+      '--packages=${globals.fs.path.join('foo', '.packages')}',
+      '-Ddart.vm.profile=true',
+      '--csp',
+      environment.buildDir.childFile('main.dart').absolute.path,
+    ];
+    verify(globals.processManager.run(expected)).called(1);
+  }, overrides: <Type, Generator>{
+    ProcessManager: () => MockProcessManager(),
+  }));
+
+
   test('Dart2JSTarget calls dart2js with expected args in profile mode', () => testbed.run(() async {
     environment.defines[kBuildMode] = 'profile';
     when(globals.processManager.run(any)).thenAnswer((Invocation invocation) async {