A crappy "netcat"-type example (in Dart).

examples/dart/netcat/main.dart

+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'dart:async';
+import 'dart:core';
+import 'dart:typed_data';
+
+import 'package:mojo/public/dart/application.dart';
+import 'package:mojo/public/dart/bindings.dart';
+import 'package:mojo/public/dart/core.dart';
+import 'package:mojo/services/files/public/interfaces/file.mojom.dart' as files;
+import 'package:mojo/services/files/public/interfaces/types.mojom.dart'
+    as files;
+import 'package:mojo/services/network/public/interfaces/net_address.mojom.dart';
+import 'package:mojo/services/network/public/interfaces/network_error.mojom.dart';
+import 'package:mojo/services/network/public/interfaces/network_service.mojom.dart';
+import 'package:mojo/services/network/public/interfaces/tcp_bound_socket.mojom.dart';
+import 'package:mojo/services/network/public/interfaces/tcp_connected_socket.mojom.dart';
+import 'package:mojo/services/terminal/public/interfaces/terminal_client.mojom.dart';
+
+void ignoreFuture(Future f) {
+  f.catchError((e) {});
+}
+
+NetAddress makeIPv4NetAddress(List<int> addr, int port) {
+  var rv = new NetAddress();
+  rv.family = NetAddressFamily_IPV4;
+  rv.ipv4 = new NetAddressIPv4();
+  rv.ipv4.addr = new List<int>.from(addr);
+  rv.ipv4.port = port;
+  return rv;
+}
+
+void fputs(files.File f, String s) {
+  ignoreFuture(f.write((s + '\n').codeUnits, 0, files.Whence_FROM_CURRENT));
+}
+
+// Connects the terminal |File| and the socket.
+// TODO(vtl):
+// * Error handling: both connection/socket errors and terminal errors.
+// * Relatedly, we should listen for _socketSender's peer being closed (also
+//   _socket, I guess).
+// * Handle the socket send pipe being full (currently, we assume it's never
+//   full).
+class Connector {
+  final Application _application;
+  final files.FileProxy _terminal;
+  TcpConnectedSocketProxy _socket;
+  MojoDataPipeProducer _socketSender;
+  MojoDataPipeConsumer _socketReceiver;
+  MojoEventStream _socketReceiverEventStream;
+  final ByteData _readBuffer;
+  final ByteData _writeBuffer;
+
+  // TODO(vtl): Don't just hard-code buffer sizes.
+  Connector(this._application, this._terminal)
+      : _readBuffer = new ByteData(16 * 1024),
+        _writeBuffer = new ByteData(16 * 1024);
+
+  Future connect(NetAddress remote_address) async {
+    var networkService = new NetworkServiceProxy.unbound();
+    _application.connectToService('mojo:network_service', networkService);
+
+    NetAddress local_address = makeIPv4NetAddress([0, 0, 0, 0], 0);
+    var boundSocket = new TcpBoundSocketProxy.unbound();
+    await networkService.ptr.createTcpBoundSocket(local_address, boundSocket);
+    await networkService.close();
+
+    var sendDataPipe = new MojoDataPipe();
+    _socketSender = sendDataPipe.producer;
+    var receiveDataPipe = new MojoDataPipe();
+    _socketReceiver = receiveDataPipe.consumer;
+    _socket = new TcpConnectedSocketProxy.unbound();
+    await boundSocket.ptr.connect(remote_address, sendDataPipe.consumer,
+        receiveDataPipe.producer, _socket);
+    await boundSocket.close();
+
+    // Set up reading from the terminal.
+    _startReadingFromTerminal();
+
+    // Set up reading from the socket.
+    _socketReceiverEventStream = new MojoEventStream(_socketReceiver.handle);
+    _socketReceiverEventStream.listen(_onSocketReceiverEvent);
+  }
+
+  void _startReadingFromTerminal() {
+    // TODO(vtl): Handle terminal errors.
+    _terminal.ptr
+        .read(_writeBuffer.lengthInBytes, 0, files.Whence_FROM_CURRENT)
+        .then(_onReadFromTerminal);
+  }
+
+  void _onReadFromTerminal(files.FileReadResponseParams p) {
+    if (p.error != files.Error_OK) {
+      // TODO(vtl): Do terminal errors.
+      return;
+    }
+
+    // TODO(vtl): Temporary hack: echo, since we don't have built-in echo
+    // support.
+    ignoreFuture(
+        _terminal.ptr.write(p.bytesRead, 0, files.Whence_FROM_CURRENT));
+
+    // TODO(vtl): Verify that |bytesRead.length| is within the expected range.
+    for (var i = 0, j = 0; i < p.bytesRead.length; i++, j++) {
+      // TODO(vtl): Temporary hack: Translate \r to \n, since we don't have
+      // built-in support for that.
+      if (p.bytesRead[i] == 13) {
+        _writeBuffer.setUint8(i, 10);
+      } else {
+        _writeBuffer.setUint8(i, p.bytesRead[i]);
+      }
+    }
+
+    // TODO(vtl): Handle the send data pipe being full (or closed).
+    _socketSender
+        .write(new ByteData.view(_writeBuffer.buffer, 0, p.bytesRead.length));
+
+    _startReadingFromTerminal();
+  }
+
+  void _onSocketReceiverEvent(List<int> event) {
+    var mojoSignals = new MojoHandleSignals(event[1]);
+    var shouldClose = false;
+    if (mojoSignals.isReadable) {
+      var numBytesRead = _socketReceiver.read(_readBuffer);
+      if (_socketReceiver.status.isOk) {
+        assert(numBytesRead > 0);
+        _terminal.ptr.write(_readBuffer.buffer.asUint8List(0, numBytesRead), 0,
+            files.Whence_FROM_CURRENT);
+        _socketReceiverEventStream.enableReadEvents();
+      } else {
+        shouldClose = true;
+      }
+    } else if (mojoSignals.isPeerClosed) {
+      shouldClose = true;
+    } else {
+      throw 'Unexpected handle event: $mojoSignals';
+    }
+    if (shouldClose) {
+      _socketReceiverEventStream.close();
+      _socketReceiverEventStream = null;
+      fputs(_terminal.ptr, 'Connection closed.');
+    }
+  }
+}
+
+class TerminalClientImpl implements TerminalClient {
+  TerminalClientStub _stub;
+  Application _application;
+  String _resolvedUrl;
+
+  TerminalClientImpl(
+      this._application, this._resolvedUrl, MojoMessagePipeEndpoint endpoint) {
+    _stub = new TerminalClientStub.fromEndpoint(endpoint, this);
+  }
+
+  @override
+  void connectToTerminal(files.FileProxy terminal) {
+    var url = Uri.parse(_resolvedUrl);
+    NetAddress remote_address;
+    try {
+      remote_address = _getNetAddressFromUrl(url);
+    } catch (e) {
+      fputs(terminal.ptr, 'HALP: Add a query: ?host=<host>&port=<port>\n'
+          '(<host> must be "localhost" or n1.n2.n3.n4)\n\n'
+          'Got query parameters:\n' + url.queryParameters.toString());
+      ignoreFuture(terminal.close());
+      return;
+    }
+
+    // TODO(vtl): Currently, we only do IPv4, so this should work.
+    fputs(terminal.ptr, 'Connecting to: ' +
+        remote_address.ipv4.addr.join('.') +
+        ':' +
+        remote_address.ipv4.port.toString() +
+        '...');
+
+    var connector = new Connector(_application, terminal);
+    connector.connect(remote_address);
+  }
+
+  // Note: May throw all sorts of things.
+  static NetAddress _getNetAddressFromUrl(Uri url) {
+    var params = url.queryParameters;
+    var host = params['host'];
+    return makeIPv4NetAddress(
+        (host == 'localhost') ? [127, 0, 0, 1] : Uri.parseIPv4Address(host),
+        int.parse(params['port']));
+  }
+}
+
+class NetcatApplication extends Application {
+  NetcatApplication.fromHandle(MojoHandle handle) : super.fromHandle(handle);
+
+  @override
+  void acceptConnection(String requestorUrl, String resolvedUrl,
+      ApplicationConnection connection) {
+    connection.provideService(TerminalClientName,
+        (endpoint) => new TerminalClientImpl(this, resolvedUrl, endpoint));
+  }
+}
+
+main(List args) {
+  MojoHandle appHandle = new MojoHandle(args[0]);
+  String url = args[1];
+  new NetcatApplication.fromHandle(appHandle)
+    ..onError = (() {
+      assert(MojoHandle.reportLeakedHandles());
+    });
+}