WebSocketChannel implementation

net/websockets/websocket_channel.h

+// Copyright 2013 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.
+
+#ifndef NET_WEBSOCKETS_WEBSOCKET_CHANNEL_H_
+#define NET_WEBSOCKETS_WEBSOCKET_CHANNEL_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "googleurl/src/gurl.h"
+#include "net/base/net_export.h"
+#include "net/websockets/websocket_frame.h"
+#include "net/websockets/websocket_stream.h"
+
+namespace net {
+
+class URLRequestContext;
+class WebSocketEventInterface;
+
+// Transport-independent implementation of WebSockets. Implements protocol
+// semantics that do not depend on the underlying transport. Provides the
+// interface to the content layer. Some WebSocket concepts are used here without
+// definition; please see the RFC at http://tools.ietf.org/html/rfc6455 for
+// clarification.
+class NET_EXPORT WebSocketChannel {
+ public:
+  // The type of a WebSocketStream factory callback. Must match the signature of
+  // WebSocketStream::CreateAndConnectStream().
+  typedef base::Callback<scoped_ptr<WebSocketStreamRequest>(
+      const GURL&,
+      const std::vector<std::string>&,
+      const GURL&,
+      URLRequestContext*,
+      const BoundNetLog&,
+      scoped_ptr<WebSocketStream::ConnectDelegate>)> WebSocketStreamFactory;
+
+  // Creates a new WebSocketChannel with the specified parameters.
+  // SendAddChannelRequest() must be called immediately afterwards to start the
+  // connection process.
+  WebSocketChannel(const GURL& socket_url,
+                   scoped_ptr<WebSocketEventInterface> event_interface);
+  virtual ~WebSocketChannel();
+
+  // Starts the connection process.
+  void SendAddChannelRequest(
+      const std::vector<std::string>& requested_protocols,
+      const GURL& origin,
+      URLRequestContext* url_request_context);
+
+  // Sends a data frame to the remote side. The frame should usually be no
+  // larger than 32KB to prevent the time required to copy the buffers from from
+  // unduly delaying other tasks that need to run on the IO thread. This method
+  // has a hard limit of 2GB. It is the responsibility of the caller to ensure
+  // that they have sufficient send quota to send this data, otherwise the
+  // connection will be closed without sending. |fin| indicates the last frame
+  // in a message, equivalent to "FIN" as specified in section 5.2 of
+  // RFC6455. |data| is the "Payload Data". If |op_code| is kOpCodeText, or it
+  // is kOpCodeContinuation and the type the message is Text, then |data| must
+  // be a chunk of a valid UTF-8 message, however there is no requirement for
+  // |data| to be split on character boundaries.
+  void SendFrame(bool fin,
+                 WebSocketFrameHeader::OpCode op_code,
+                 const std::vector<char>& data);
+
+  // Sends |quota| units of flow control to the remote side. If the underlying
+  // transport has a concept of |quota|, then it permits the remote server to
+  // send up to |quota| units of data.
+  void SendFlowControl(int64 quota);
+
+  // Start the closing handshake for a client-initiated shutdown of the
+  // connection. There is no API to close the connection without a closing
+  // handshake, but destroying the WebSocketChannel object while connected will
+  // effectively do that. |code| must be in the range 1000-4999. |reason| should
+  // be a valid UTF-8 string or empty.
+  //
+  // This does *not* trigger the event OnClosingHandshake(). The caller should
+  // assume that the closing handshake has started and perform the equivalent
+  // processing to OnClosingHandshake() if necessary.
+  void StartClosingHandshake(uint16 code, const std::string& reason);
+
+  // Starts the connection process, using a specified factory function rather
+  // than the default. This is exposed for testing.
+  void SendAddChannelRequestForTesting(
+      const std::vector<std::string>& requested_protocols,
+      const GURL& origin,
+      URLRequestContext* url_request_context,
+      const WebSocketStreamFactory& factory);
+
+ private:
+  // We have a simple linear progression of states from FRESHLY_CONSTRUCTED to
+  // CLOSED, except that the SEND_CLOSED and RECV_CLOSED states may be skipped
+  // in case of error.
+  enum State {
+    FRESHLY_CONSTRUCTED,
+    CONNECTING,
+    CONNECTED,
+    SEND_CLOSED,  // We have sent a Close frame but not received a Close frame.
+    RECV_CLOSED,  // Used briefly between receiving a Close frame and sending
+                  // the response. Once we have responded, the state changes
+                  // to CLOSED.
+    CLOSED,  // The Closing Handshake has completed or the connection is failed.
+  };
+
+  // When failing a channel, we may or may not want to send the real reason for
+  // failing to the remote server. This enum is used by FailChannel() to
+  // choose.
+  enum ExposeError {
+    SEND_REAL_ERROR,
+    SEND_GOING_AWAY,
+  };
+
+  // Our implementation of WebSocketStream::ConnectDelegate. We do not inherit
+  // from WebSocketStream::ConnectDelegate directly to avoid cluttering our
+  // public interface with the implementation of those methods, and because the
+  // lifetime of a WebSocketChannel is longer than the lifetime of the
+  // connection process.
+  class ConnectDelegate;
+
+  // Starts the connection progress, using a specified factory function.
+  void SendAddChannelRequestWithFactory(
+      const std::vector<std::string>& requested_protocols,
+      const GURL& origin,
+      URLRequestContext* url_request_context,
+      const WebSocketStreamFactory& factory);
+
+  // Success callback from WebSocketStream::CreateAndConnectStream(). Reports
+  // success to the event interface.
+  void OnConnectSuccess(scoped_ptr<WebSocketStream> stream);
+
+  // Failure callback from WebSocketStream::CreateAndConnectStream(). Reports
+  // failure to the event interface.
+  void OnConnectFailure(uint16 websocket_error);
+
+  // Calls WebSocketStream::WriteFrames() with the appropriate arguments
+  void WriteFrames();
+
+  // Callback from WebSocketStream::WriteFrames. Sends pending data or adjusts
+  // the send quota of the renderer channel as appropriate. |result| is a net
+  // error code, usually OK. If |synchronous| is true, then OnWriteDone() is
+  // being called from within the WriteFrames() loop and does not need to call
+  // WriteFrames() itself.
+  void OnWriteDone(bool synchronous, int result);
+
+  // Calls WebSocketStream::ReadFrames() with the appropriate arguments.
+  void ReadFrames();
+
+  // Callback from WebSocketStream::ReadFrames. Handles any errors and processes
+  // the returned chunks appropriately to their type. |result| is a net error
+  // code. If |synchronous| is true, then OnReadDone() is being called from
+  // within the ReadFrames() loop and does not need to call ReadFrames() itself.
+  void OnReadDone(bool synchronous, int result);
+
+  // Processes a single chunk that has been read from the stream.
+  void ProcessFrameChunk(scoped_ptr<WebSocketFrameChunk> chunk);
+
+  // Handle a frame that we have received enough of to process. May call
+  // event_interface_ methods, send responses to the server, and change the
+  // value of state_.
+  void HandleFrame(const WebSocketFrameHeader::OpCode opcode,
+                   bool is_first_chunk,
+                   bool is_final_chunk,
+                   const scoped_refptr<IOBufferWithSize>& data_buffer);
+
+  // Low-level method to send a single frame. Used for both data and control
+  // frames. Either sends the frame immediately or buffers it to be scheduled
+  // when the current write finishes. |fin| and |op_code| are defined as for
+  // SendFrame() above, except that |op_code| may also be a control frame
+  // opcode.
+  void SendIOBufferWithSize(bool fin,
+                            WebSocketFrameHeader::OpCode op_code,
+                            const scoped_refptr<IOBufferWithSize>& buffer);
+
+  // Perform the "Fail the WebSocket Connection" operation as defined in
+  // RFC6455. The supplied code and reason are sent back to the renderer in an
+  // OnDropChannel message. If state_ is CONNECTED then a Close message is sent
+  // to the remote host. If |expose| is SEND_REAL_ERROR then the remote host is
+  // given the same status code we gave the renderer; otherwise it is sent a
+  // fixed "Going Away" code.  Resets current_frame_header_, closes the
+  // stream_, and sets state_ to CLOSED.
+  void FailChannel(ExposeError expose, uint16 code, const std::string& reason);
+
+  // Sends a Close frame to Start the WebSocket Closing Handshake, or to respond
+  // to a Close frame from the server.
+  void SendClose(uint16 code, const std::string& reason);
+
+  // Parses a Close frame. If no status code is supplied, then |code| is set to
+  // 1005 (No status code) with empty |reason|. If the supplied code is
+  // outside the valid range, then 1002 (Protocol error) is set instead. If the
+  // reason text is not valid UTF-8, then |reason| is set to an empty string
+  // instead.
+  void ParseClose(const scoped_refptr<IOBufferWithSize>& buffer,
+                  uint16* code,
+                  std::string* reason);
+
+  // The URL to which we connect.
+  const GURL socket_url_;
+
+  // The object receiving events.
+  const scoped_ptr<WebSocketEventInterface> event_interface_;
+
+  // The WebSocketStream to which we are sending/receiving data.
+  scoped_ptr<WebSocketStream> stream_;
+
+  // A data structure containing a vector of frames to be sent and the total
+  // number of bytes contained in the vector.
+  class SendBuffer;
+  // Data that is currently pending write, or NULL if no write is pending.
+  scoped_ptr<SendBuffer> data_being_sent_;
+  // Data that is queued up to write after the current write completes.
+  // Only non-NULL when such data actually exists.
+  scoped_ptr<SendBuffer> data_to_send_next_;
+
+  // Destination for the current call to WebSocketStream::ReadFrames
+  ScopedVector<WebSocketFrameChunk> read_frame_chunks_;
+  // Frame header for the frame currently being received. Only non-NULL while we
+  // are processing the frame. If the frame arrives in multiple chunks, can
+  // remain non-NULL while we wait for additional chunks to arrive. If the
+  // header of the frame was invalid, this is set to NULL, the channel is
+  // failed, and subsequent chunks of the same frame will be ignored.
+  scoped_ptr<WebSocketFrameHeader> current_frame_header_;
+  // Handle to an in-progress WebSocketStream creation request. Only non-NULL
+  // during the connection process.
+  scoped_ptr<WebSocketStreamRequest> stream_request_;
+  // Although it will almost never happen in practice, we can be passed an
+  // incomplete control frame, in which case we need to keep the data around
+  // long enough to reassemble it. This variable will be NULL the rest of the
+  // time.
+  scoped_refptr<IOBufferWithSize> incomplete_control_frame_body_;
+  // The point at which we give the renderer a quota refresh (quota units).
+  // "quota units" are currently bytes. TODO(ricea): Update the definition of
+  // quota units when necessary.
+  int send_quota_low_water_mark_;
+  // The amount which we refresh the quota to when it reaches the
+  // low_water_mark (quota units).
+  int send_quota_high_water_mark_;
+  // The current amount of quota that the renderer has available for sending
+  // on this logical channel (quota units).
+  int current_send_quota_;
+
+  // Storage for the status code and reason from the time we receive the Close
+  // frame until the connection is closed and we can call OnDropChannel().
+  uint16 closing_code_;
+  std::string closing_reason_;
+
+  // The current state of the channel. Mainly used for sanity checking, but also
+  // used to track the close state.
+  State state_;
+
+  DISALLOW_COPY_AND_ASSIGN(WebSocketChannel);
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_CHANNEL_H_