Add secure sockets to dart:io

sdk/lib/io/tls_socket.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/**
+ * TlsSocket provides a secure (SSL or TLS) client connection to a server.
+ * The certificate provided by the server is checked
+ * using the certificate database provided in setCertificateDatabase.
+ */
+abstract class TlsSocket implements Socket {
+  /**
+   * Constructs a new secure socket and connect it to the given
+   * host on the given port. The returned socket is not yet connected
+   * but ready for registration of callbacks.
+   */
+  factory TlsSocket(String host, int port) => new _TlsSocket(host, port);
+
+  /**
+   * Initializes the TLS library with the path to a certificate database
+   * containing root certificates for verifying certificate paths on
+   * client connections, and server certificates to provide on server
+   * connections.
+   */
+  external static void setCertificateDatabase(String pkcertDirectory);
+}
+
+
+class _TlsSocket implements TlsSocket {
+  // Status states
+  static final int NOT_CONNECTED = 200;
+  static final int HANDSHAKE = 201;
+  static final int CONNECTED = 202;
+  static final int CLOSED = 203;
+
+  // Buffer identifiers.
+  // These must agree with those in the native C++ implementation.
+  static final int READ_PLAINTEXT = 0;
+  static final int WRITE_PLAINTEXT = 1;
+  static final int READ_ENCRYPTED = 2;
+  static final int WRITE_ENCRYPTED = 3;
+  static final int NUM_BUFFERS = 4;
+
+  int _count = 0;
+  // Constructs a new secure client socket.
+  _TlsSocket(String host, int port)
+      : _host = host,
+        _port = port,
+        _socket = new Socket(host, port),
+        _tlsFilter = new _TlsFilter() {
+    _socket.onConnect = _tlsConnectHandler;
+    _socket.onData = _tlsDataHandler;
+    _socket.onClosed = _tlsCloseHandler;
+    _tlsFilter.init();
+    _tlsFilter.registerHandshakeCallbacks(_tlsHandshakeStartHandler,
+                                          _tlsHandshakeFinishHandler);
+  }
+
+  InputStream get inputStream {
+    // TODO(6701): Implement stream interfaces on TlsSocket.
+    throw new UnimplementedError("TlsSocket.inputStream not implemented yet");
+  }
+
+  int get port => _socket.port;
+
+  String get remoteHost => _socket.remoteHost;
+
+  int get remotePort => _socket.remotePort;
+
+  void set onClosed(void callback()) {
+    _socketCloseHandler = callback;
+  }
+
+  void set onConnect(void callback()) {
+    _socketConnectHandler = callback;
+  }
+
+  void set onData(void callback()) {
+    _socketDataHandler = callback;
+  }
+
+  void set onWrite(void callback()) {
+    _socketWriteHandler = callback;
+    // Reset the one-shot onWrite handler.
+    _socket.onWrite = _tlsWriteHandler;
+  }
+
+  OutputStream get outputStream {
+    // TODO(6701): Implement stream interfaces on TlsSocket.
+    throw new UnimplementedError("TlsSocket.inputStream not implemented yet");
+  }
+
+  int available() {
+    throw new UnimplementedError("TlsSocket.available not implemented yet");
+  }
+
+  void close([bool halfClose]) {
+    _socket.close(halfClose);
+  }
+
+  List<int> read([int len]) {
+    var buffer = _tlsFilter.buffers[READ_PLAINTEXT];
+    _readEncryptedData();
+    int toRead = buffer.length;
+    if (len != null) {
+      if (len is! int || len < 0) {
+        throw new ArgumentError(
+            "Invalid len parameter in TlsSocket.read (len: $len)");
+      }
+      if (len < toRead) {
+        toRead = len;
+      }
+      }

[Søren Gjesse, 2012/11/14 08:18:59]

Indentation

[Bill Hesse, 2012/11/14 13:33:30]

Done.

+    List<int> result = buffer.data.getRange(buffer.start, toRead);
+    buffer.advanceStart(toRead);
+    _setHandlersAfterRead();
+    return result;
+  }
+
+  int readList(List<int> data, int offset, int bytes) {
+    if (offset < 0 || bytes < 0 || offset + bytes > data.length) {
+      throw new ArgumentError(
+          "Invalid offset or bytes in TlsSocket.readList");
+    }
+
+    int bytesRead = 0;
+    var buffer = _tlsFilter.buffers[READ_PLAINTEXT];
+    // TODO(whesse): Currently this fails if the if is turned into a while loop.
+    // Fix it so that it can loop and read more than one buffer's worth of data.
+    if (bytes > bytesRead) {
+      _readEncryptedData();
+      if (buffer.length > 0) {
+        int toRead = min(bytes - bytesRead, buffer.length);
+        data.setRange(offset, toRead, buffer.data, buffer.start);
+        buffer.advanceStart(toRead);
+        bytesRead += toRead;
+        offset += toRead;
+      }
+    }
+
+    _setHandlersAfterRead();
+    return bytesRead;
+  }
+
+  // Write the data to the socket, and flush it as much as possible
+  // until it blocks.  If the write blocks, _writeEncryptedData sets

[Søren Gjesse, 2012/11/14 08:18:59]

Please change block to "would block" (or something like that) - we never block.

[Bill Hesse, 2012/11/14 13:33:30]

Done.

+  // up handlers to flush the pipeline when possible.
+  int writeList(List<int> data, int offset, int bytes) {
+    var buffer = _tlsFilter.buffers[WRITE_PLAINTEXT];
+    if (bytes > buffer.free) {
+      bytes = buffer.free;
+    }
+    if (bytes > 0) {
+      buffer.data.setRange(buffer.start + buffer.length, bytes, data, offset);
+      buffer.length += bytes;
+    }
+    _writeEncryptedData();  // Tries to flush all pipeline stages.
+    return bytes;
+  }
+
+  void _tlsConnectHandler() {
+    _connectPending = true;
+    _tlsFilter.connect(_host, _port);
+    _tlsHandshake();
+  }
+
+  void _tlsWriteHandler() {
+    if (_status == HANDSHAKE) {
+      _tlsHandshake();
+    } else if (_status == CONNECTED) {
+      if (_socketWriteHandler != null) {
+        _socketWriteHandler();
+      }
+    }
+  }
+
+  void _tlsDataHandler() {
+    if (_status == HANDSHAKE) {
+      _tlsHandshake();
+    } else {
+      _writeEncryptedData();  // TODO(whesse): Removing this causes a failure.
+      _readEncryptedData();
+      var buffer = _tlsFilter.buffers[READ_PLAINTEXT];
+      if (_filterEmpty) {
+        if (_fireCloseEventPending) {
+          _fireCloseEvent();
+        }
+      } else {  // Filter is not empty.
+        if (scheduledDataEvent != null) {
+          scheduledDataEvent.cancel();
+          scheduledDataEvent = null;
+        }
+        if (_socketDataHandler != null) {
+          _socketDataHandler();
+        }
+      }
+    }
+  }
+
+  void _tlsCloseHandler() {
+    _socketClosed = true;
+    _status = CLOSED;
+    _socket.close();
+    if (_filterEmpty) {
+      _fireCloseEvent();
+    } else {
+      _fireCloseEventPending = true;
+    }
+  }
+
+  void _tlsHandshake() {
+      _readEncryptedData();
+      _tlsFilter.handshake();
+      _writeEncryptedData();
+      if (_tlsFilter.buffers[WRITE_ENCRYPTED].length > 0) {
+        _socket.onWrite = _tlsWriteHandler;
+      }
+  }
+
+  void _tlsHandshakeStartHandler() {
+    _status = HANDSHAKE;
+  }
+
+  void _tlsHandshakeFinishHandler() {
+    _status = CONNECTED;
+    if (_connectPending && _socketConnectHandler != null) {
+      _connectPending = false;
+      _socketConnectHandler();
+    }
+  }
+
+  void _fireCloseEvent() {
+    _fireCloseEventPending = false;
+    _tlsFilter.destroy();
+    _tlsFilter = null;
+    if (scheduledDataEvent != null) {
+      scheduledDataEvent.cancel();
+    }
+    if (_socketCloseHandler != null) {
+      _socketCloseHandler();
+    }
+  }
+
+  void _readEncryptedData() {
+    // Read from the socket, and push it through the filter as far as
+    // possible.
+    var encrypted = _tlsFilter.buffers[READ_ENCRYPTED];
+    var plaintext = _tlsFilter.buffers[READ_PLAINTEXT];
+    bool progress = true;
+    while (progress) {
+      progress = false;
+      // Do not try to read plaintext from the filter while handshaking.
+      if ((_status == CONNECTED || _status == CLOSED) && plaintext.free > 0) {

[Søren Gjesse, 2012/11/14 08:18:59]

Why are we trying to process data when closed?

[Bill Hesse, 2012/11/14 13:33:30]

The status == CLOSED is the status when the underlying socket is closed.  We may
still have data in our read buffers and filter, and will not send a close event
until those are empty.  Maybe we should split this into two states, CLOSED and
CLOSE_PENDING.

+        int bytes = _tlsFilter.processBuffer(READ_PLAINTEXT);
+        if (bytes > 0) {
+          plaintext.length += bytes;
+          progress = true;
+        }
+      }
+      if (encrypted.length > 0) {
+        int bytes = _tlsFilter.processBuffer(READ_ENCRYPTED);
+        if (bytes > 0) {
+          encrypted.advanceStart(bytes);
+          progress = true;
+        }
+      }
+      if (!_socketClosed) {
+        int bytes = _socket.readList(encrypted.data,
+                                     encrypted.start + encrypted.length,
+                                     encrypted.free);
+        if (bytes > 0) {
+          encrypted.length += bytes;
+          progress = true;
+        }
+      }
+    }
+    // TODO(whesse): This can be incorrect if there is a partial
+    // encrypted block stuck in the tlsFilter, and no other data.
+    // Fix this - we do need to know when the filter is empty.
+    _filterEmpty = (plaintext.length == 0);
+  }
+
+  void _writeEncryptedData() {
+    // Write from the filter to the socket.
+    var buffer = _tlsFilter.buffers[WRITE_ENCRYPTED];
+    while (true) {
+      if (buffer.length > 0) {
+        int bytes = _socket.writeList(buffer.data, buffer.start, buffer.length);
+        if (bytes == 0) {
+          // The socket has blocked while we have data to write.
+          // We must be notified when it becomes unblocked.
+          _socket.onWrite = _tlsWriteHandler;
+          break;
+        }
+        buffer.advanceStart(bytes);
+      } else {
+        var plaintext = _tlsFilter.buffers[WRITE_PLAINTEXT];
+        if (plaintext.length > 0) {
+           int plaintext_bytes = _tlsFilter.processBuffer(WRITE_PLAINTEXT);
+           plaintext.advanceStart(plaintext_bytes);
+        }
+        int bytes = _tlsFilter.processBuffer(WRITE_ENCRYPTED);
+        if (bytes <= 0) break;
+        buffer.length += bytes;
+      }
+    }
+  }
+
+  /* After a read, the onData handler is enabled to fire again.
+   * We may also have a close event waiting for the TlsFilter to empty.
+   */
+  void _setHandlersAfterRead() {
+    // If the filter is empty, then we are guaranteed an event when it
+    // becomes unblocked.
+    // Otherwise, schedule a _tlsDataHandler call since there may data
+    // available, and this read call enables the data event.
+    if (!_filterEmpty && scheduledDataEvent == null) {
+      scheduledDataEvent = new Timer(0, (_) => _tlsDataHandler());
+    } else if (_filterEmpty && scheduledDataEvent != null) {
+        scheduledDataEvent.cancel();
+        scheduledDataEvent = null;
+    }
+    if (_filterEmpty && _fireCloseEventPending) {
+        _fireCloseEvent();
+    }
+  }
+
+  // _TlsSocket cannot extend _Socket and use _Socket's factory constructor.
+  Socket _socket;
+  String _host;
+  int _port;
+
+  var _status = NOT_CONNECTED;
+  bool _socketClosed = false;
+  bool _filterEmpty = false;
+  bool _connectPending = false;
+  bool _fireCloseEventPending = false;
+  Function _socketConnectHandler;
+  Function _socketWriteHandler;
+  Function _socketDataHandler;
+  Function _socketCloseHandler;
+  Timer scheduledDataEvent;
+
+  _TlsFilter _tlsFilter;
+}
+
+

[Søren Gjesse, 2012/11/14 08:18:59]

Could this maybe be made into a real circular buffer?

[Bill Hesse, 2012/11/14 13:33:30]

Added as a TODO.  I would not do this until we have performance measurement in
place.  It adds complexity, and may not be hit in the normal use case.

+class _TlsExternalBuffer {
+  static final int SIZE = 8 * 1024;
+  _TlsExternalBuffer() : start = 0, length = 0;
+
+  void advanceStart(int numBytes) {
+    start += numBytes;
+    length -= numBytes;
+    if (length == 0) {
+      start = 0;
+    }
+  }
+
+  int get free => SIZE - (start + length);
+
+  List data;  // This will be a ExternalByteArray, backed by C allocated data.
+  int start;
+  int length;
+}
+
+
+abstract class _TlsFilter {
+  external factory _TlsFilter();
+
+  void connect(String hostName, int port);
+  void destroy();
+  void handshake();
+  void init();
+  int processBuffer(int bufferIndex);
+  void registerHandshakeCallbacks(Function startHandshakeHandler,
+                                  Function finishHandshakeHandler);
+}