Split out TLS credentials to a separate class. (#60)

Add a 'bad certificate handler' to the new ChannelCredentials, which can
be used to override certificate validation (for example, to allow
auto-generated self-signed certificates during development).

Also fixed a bug in Server.shutdown().

example/googleapis/bin/logging.dart

@@ -40,8 +40,7 @@ Future<Null> main() async {
       serviceAccountFile.readAsStringSync(), scopes);
   final projectId = authenticator.projectId;
 
-  final channel = new ClientChannel('logging.googleapis.com',
-      options: const ChannelOptions.secure());
+  final channel = new ClientChannel('logging.googleapis.com');
   final logging =
       new LoggingServiceV2Client(channel, options: authenticator.toCallOptions);
 

example/helloworld/bin/client.dart

@@ -23,7 +23,9 @@ import 'package:helloworld/src/generated/helloworld.pbgrpc.dart';
 
 Future<Null> main(List<String> args) async {
   final channel = new ClientChannel('localhost',
-      port: 50051, options: const ChannelOptions.insecure());
+      port: 50051,
+      options: const ChannelOptions(
+          credentials: const ChannelCredentials.insecure()));
   final stub = new GreeterClient(channel);
 
   final name = args.isNotEmpty ? args[0] : 'world';

example/metadata/lib/src/client.dart

@@ -25,7 +25,9 @@ class Client {
 
   Future<Null> main(List<String> args) async {
     channel = new ClientChannel('127.0.0.1',
-        port: 8080, options: const ChannelOptions.insecure());
+        port: 8080,
+        options: const ChannelOptions(
+            credentials: const ChannelCredentials.insecure()));
     stub = new MetadataClient(channel);
     // Run all of the demos in order.
     await runEcho();

example/route_guide/lib/src/client.dart

@@ -28,7 +28,9 @@ class Client {
 
   Future<Null> main(List<String> args) async {
     channel = new ClientChannel('127.0.0.1',
-        port: 8080, options: const ChannelOptions.insecure());
+        port: 8080,
+        options: const ChannelOptions(
+            credentials: const ChannelCredentials.insecure()));
     stub = new RouteGuideClient(channel,
         options: new CallOptions(timeout: new Duration(seconds: 30)));
     // Run all of the demos in order.

example/route_guide/lib/src/server.dart

@@ -25,8 +25,9 @@ import 'generated/route_guide.pbgrpc.dart';
 class RouteGuideService extends RouteGuideServiceBase {
   final routeNotes = <Point, List<RouteNote>>{};
 
-  // getFeature handler. Returns a feature for the given location.
-  // The [context] object provides access to client metadata, cancellation, etc.
+  /// GetFeature handler. Returns a feature for the given location.
+  /// The [context] object provides access to client metadata, cancellation, etc.
+  @override
   Future<Feature> getFeature(grpc.ServiceCall call, Point request) async {
     return featuresDb.firstWhere((f) => f.location == request,
         orElse: () => new Feature()..location = request);
@@ -53,8 +54,9 @@ class RouteGuideService extends RouteGuideServiceBase {
         p.latitude <= r.hi.latitude;
   }
 
-  /// listFeatures handler. Returns a stream of features within the given
+  /// ListFeatures handler. Returns a stream of features within the given
   /// rectangle.
+  @override
   Stream<Feature> listFeatures(
       grpc.ServiceCall call, Rectangle request) async* {
     final normalizedRectangle = _normalize(request);
@@ -68,9 +70,10 @@ class RouteGuideService extends RouteGuideServiceBase {
     }
   }
 
-  /// recordRoute handler. Gets a stream of points, and responds with statistics
+  /// RecordRoute handler. Gets a stream of points, and responds with statistics
   /// about the "trip": number of points, number of known features visited,
   /// total distance traveled, and total time spent.
+  @override
   Future<RouteSummary> recordRoute(
       grpc.ServiceCall call, Stream<Point> request) async {
     int pointCount = 0;
@@ -100,9 +103,10 @@ class RouteGuideService extends RouteGuideServiceBase {
       ..elapsedTime = timer.elapsed.inSeconds;
   }
 
-  /// routeChat handler. Receives a stream of message/location pairs, and
+  /// RouteChat handler. Receives a stream of message/location pairs, and
   /// responds with a stream of all previous messages at each of those
   /// locations.
+  @override
   Stream<RouteNote> routeChat(
       grpc.ServiceCall call, Stream<RouteNote> request) async* {
     await for (var note in request) {

interop/lib/src/client.dart

@@ -89,18 +89,19 @@ class Tester {
   }
 
   Future<Null> runTest() async {
-    ChannelOptions options;
+    ChannelCredentials credentials;
     if (_useTls) {
       List<int> trustedRoot;
       if (_useTestCA) {
         trustedRoot = new File('ca.pem').readAsBytesSync();
       }
-      options = new ChannelOptions.secure(
-          certificate: trustedRoot, authority: serverHostOverride);
+      credentials = new ChannelCredentials.secure(
+          certificates: trustedRoot, authority: serverHostOverride);
     } else {
-      options = new ChannelOptions.insecure();
+      credentials = const ChannelCredentials.insecure();
     }
 
+    final options = new ChannelOptions(credentials: credentials);
     channel =
         new ClientChannel(serverHost, port: _serverPort, options: options);
     client = new TestServiceClient(channel);

lib/src/client/call.dart

@@ -93,7 +93,7 @@ class ClientCall<Q, R> implements Response {
     } else {
       final metadata = new Map.from(options.metadata);
       String audience;
-      if (connection.options.isSecure) {
+      if (connection.options.credentials.isSecure) {
         final port = connection.port != 443 ? ':${connection.port}' : '';
         final lastSlashPos = path.lastIndexOf('/');
         final audiencePath =

lib/src/client/channel.dart

@@ -38,7 +38,7 @@ class ClientChannel {
   bool _isShutdown = false;
 
   ClientChannel(this.host,
-      {this.port = 443, this.options = const ChannelOptions.secure()});
+      {this.port = 443, this.options = const ChannelOptions()});
 
   /// Shuts down this channel.
   ///

lib/src/client/connection.dart

@@ -96,11 +96,11 @@ class ClientConnection {
     return headers;
   }
 
-  String get authority => options.authority ?? host;
+  String get authority => options.credentials.authority ?? host;
 
   @visibleForTesting
   Future<ClientTransportConnection> connectTransport() async {
-    final securityContext = options.securityContext;
+    final securityContext = options.credentials.securityContext;
 
     var socket = await Socket.connect(host, port);
     if (_state == ConnectionState.shutdown) {
@@ -109,7 +109,9 @@ class ClientConnection {
     }
     if (securityContext != null) {
       socket = await SecureSocket.secure(socket,
-          host: authority, context: securityContext);
+          host: authority,
+          context: securityContext,
+          onBadCertificate: _validateBadCertificate);
       if (_state == ConnectionState.shutdown) {
         socket.destroy();
         throw 'Shutting down';
@@ -119,6 +121,12 @@ class ClientConnection {
     return new ClientTransportConnection.viaSocket(socket);
   }
 
+  bool _validateBadCertificate(X509Certificate certificate) {
+    final validator = options.credentials.onBadCertificate;
+    if (validator == null) return false;
+    return validator(certificate, authority);
+  }
+
   void _connect() {
     if (_state != ConnectionState.idle &&
         _state != ConnectionState.transientFailure) {
@@ -153,8 +161,8 @@ class ClientConnection {
 
   ClientTransportStream makeRequest(
       String path, Duration timeout, Map<String, String> metadata) {
-    final headers =
-        createCallHeaders(options.isSecure, authority, path, timeout, metadata);
+    final headers = createCallHeaders(
+        options.credentials.isSecure, authority, path, timeout, metadata);
     return _transport.makeRequest(headers);
   }
 

lib/src/client/options.dart

@@ -39,43 +39,40 @@ Duration defaultBackoffStrategy(Duration lastBackoff) {
   return nextBackoff < _maxBackoff ? nextBackoff : _maxBackoff;
 }
 
-/// Options controlling how connections are made on a [ClientChannel].
-class ChannelOptions {
+/// Handler for checking certificates that fail validation. If this handler
+/// returns `true`, the bad certificate is allowed, and the TLS handshake can
+/// continue. If the handler returns `false`, the TLS handshake fails, and the
+/// connection is aborted.
+typedef bool BadCertificateHandler(X509Certificate certificate, String host);
+
+/// Bad certificate handler that disables all certificate checks.
+/// DO NOT USE IN PRODUCTION!
+/// Can be used during development and testing to accept self-signed
+/// certificates, etc.
+bool allowBadCertificates(X509Certificate certificate, String host) => true;
+
+/// Options controlling TLS security settings on a [ClientChannel].
+class ChannelCredentials {
   final bool isSecure;
   final List<int> _certificateBytes;
   final String _certificatePassword;
   final String authority;
-  final Duration idleTimeout;
-  final BackoffStrategy backoffStrategy;
+  final BadCertificateHandler onBadCertificate;
 
-  const ChannelOptions._(
-      this.isSecure,
-      this._certificateBytes,
-      this._certificatePassword,
-      this.authority,
-      Duration idleTimeout,
-      BackoffStrategy backoffStrategy)
-      : this.idleTimeout = idleTimeout ?? defaultIdleTimeout,
-        this.backoffStrategy = backoffStrategy ?? defaultBackoffStrategy;
+  const ChannelCredentials._(this.isSecure, this._certificateBytes,
+      this._certificatePassword, this.authority, this.onBadCertificate);
 
   /// Disable TLS. RPCs are sent in clear text.
-  const ChannelOptions.insecure(
-      {Duration idleTimeout,
-      BackoffStrategy backoffStrategy =
-          defaultBackoffStrategy}) // Remove when dart-lang/sdk#31066 is fixed.
-      : this._(false, null, null, null, idleTimeout, backoffStrategy);
+  const ChannelCredentials.insecure() : this._(false, null, null, null, null);
 
-  /// Enable TLS and optionally specify the [certificate]s to trust. If
+  /// Enable TLS and optionally specify the [certificates] to trust. If
   /// [certificates] is not provided, the default trust store is used.
-  const ChannelOptions.secure(
-      {List<int> certificate,
+  const ChannelCredentials.secure(
+      {List<int> certificates,
       String password,
       String authority,
-      Duration idleTimeout,
-      BackoffStrategy backoffStrategy =
-          defaultBackoffStrategy}) // Remove when dart-lang/sdk#31066 is fixed.
-      : this._(true, certificate, password, authority, idleTimeout,
-            backoffStrategy);
+      BadCertificateHandler onBadCertificate})
+      : this._(true, certificates, password, authority, onBadCertificate);
 
   SecurityContext get securityContext {
     if (!isSecure) return null;
@@ -92,6 +89,22 @@ class ChannelOptions {
   }
 }
 
+/// Options controlling how connections are made on a [ClientChannel].
+class ChannelOptions {
+  final ChannelCredentials credentials;
+  final Duration idleTimeout;
+  final BackoffStrategy backoffStrategy;
+
+  const ChannelOptions(
+      {ChannelCredentials credentials,
+      Duration idleTimeout,
+      BackoffStrategy backoffStrategy =
+          defaultBackoffStrategy}) // Remove when dart-lang/sdk#31066 is fixed.
+      : this.credentials = credentials ?? const ChannelCredentials.secure(),
+        this.idleTimeout = idleTimeout ?? defaultIdleTimeout,
+        this.backoffStrategy = backoffStrategy ?? defaultBackoffStrategy;
+}
+
 /// Provides per-RPC metadata.
 ///
 /// Metadata providers will be invoked for every RPC, and can add their own

lib/src/server/server.dart

@@ -100,7 +100,7 @@ class Server {
     new ServerHandler(lookupService, stream).handle();
   }
 
-  Future<Null> shutdown() {
+  Future<Null> shutdown() async {
     final done = _connections.map((connection) => connection.finish()).toList();
     if (_insecureServer != null) {
       done.add(_insecureServer.close());
@@ -108,6 +108,6 @@ class Server {
     if (_secureServer != null) {
       done.add(_secureServer.close());
     }
-    return Future.wait(done);
+    await Future.wait(done);
   }
 }

test/options_test.dart

@@ -23,19 +23,19 @@ const isTlsException = const isInstanceOf<TlsException>();
 void main() {
   group('Certificates', () {
     test('report password errors correctly', () async {
-      final certificate =
+      final certificates =
           await new File('test/data/certstore.p12').readAsBytes();
 
       final missingPassword =
-          new ChannelOptions.secure(certificate: certificate);
+          new ChannelCredentials.secure(certificates: certificates);
       expect(() => missingPassword.securityContext, throwsA(isTlsException));
 
-      final wrongPassword = new ChannelOptions.secure(
-          certificate: certificate, password: 'wrong');
+      final wrongPassword = new ChannelCredentials.secure(
+          certificates: certificates, password: 'wrong');
       expect(() => wrongPassword.securityContext, throwsA(isTlsException));
 
-      final correctPassword = new ChannelOptions.secure(
-          certificate: certificate, password: 'correct');
+      final correctPassword = new ChannelCredentials.secure(
+          certificates: certificates, password: 'correct');
       expect(correctPassword.securityContext, isNotNull);
     });
   });

test/src/client_utils.dart

@@ -15,7 +15,6 @@
 
 import 'dart:async';
 
-import 'dart:io';
 import 'package:grpc/src/shared/streams.dart';
 import 'package:http2/transport.dart';
 import 'package:test/test.dart';
@@ -47,11 +46,9 @@ class FakeConnection extends ClientConnection {
 Duration testBackoff(Duration lastBackoff) => const Duration(milliseconds: 1);
 
 class FakeChannelOptions implements ChannelOptions {
-  String authority;
+  ChannelCredentials credentials = const ChannelCredentials.secure();
   Duration idleTimeout = const Duration(seconds: 1);
   BackoffStrategy backoffStrategy = testBackoff;
-  SecurityContext securityContext = new SecurityContext();
-  bool isSecure = true;
 }
 
 class FakeChannel extends ClientChannel {