1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_
6#define NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_
7
8#include <vector>
9
10#include "base/basictypes.h"
11#include "base/memory/ref_counted.h"
12#include "base/memory/scoped_ptr.h"
13#include "base/memory/scoped_vector.h"
14#include "net/base/net_export.h"
15#include "net/websockets/websocket_errors.h"
16#include "net/websockets/websocket_frame.h"
17
18namespace net {
19
20// Parses WebSocket frames from byte stream.
21//
22// Specification of WebSocket frame format is available at
23// <http://tools.ietf.org/html/rfc6455#section-5>.
24
25class NET_EXPORT WebSocketFrameParser {
26 public:
27  WebSocketFrameParser();
28  ~WebSocketFrameParser();
29
30  // Decodes the given byte stream and stores parsed WebSocket frames in
31  // |frame_chunks|.
32  //
33  // If the parser encounters invalid payload length format, Decode() fails
34  // and returns false. Once Decode() has failed, the parser refuses to decode
35  // any more data and future invocations of Decode() will simply return false.
36  //
37  // Payload data of parsed WebSocket frames may be incomplete; see comments in
38  // websocket_frame.h for more details.
39  bool Decode(const char* data,
40              size_t length,
41              ScopedVector<WebSocketFrameChunk>* frame_chunks);
42
43  // Returns kWebSocketNormalClosure if the parser has not failed to decode
44  // WebSocket frames. Otherwise returns WebSocketError which is defined in
45  // websocket_errors.h. We can convert net::WebSocketError to net::Error by
46  // using WebSocketErrorToNetError().
47  WebSocketError websocket_error() const { return websocket_error_; }
48
49 private:
50  // Tries to decode a frame header from |current_read_pos_|.
51  // If successful, this function updates |current_read_pos_|,
52  // |current_frame_header_|, and |masking_key_| (if available).
53  // This function may set |failed_| to true if it observes a corrupt frame.
54  // If there is not enough data in the remaining buffer to parse a frame
55  // header, this function returns without doing anything.
56  void DecodeFrameHeader();
57
58  // Decodes frame payload and creates a WebSocketFrameChunk object.
59  // This function updates |current_read_pos_| and |frame_offset_| after
60  // parsing. This function returns a frame object even if no payload data is
61  // available at this moment, so the receiver could make use of frame header
62  // information. If the end of frame is reached, this function clears
63  // |current_frame_header_|, |frame_offset_| and |masking_key_|.
64  scoped_ptr<WebSocketFrameChunk> DecodeFramePayload(bool first_chunk);
65
66  // Internal buffer to store the data to parse.
67  std::vector<char> buffer_;
68
69  // Position in |buffer_| where the next round of parsing starts.
70  size_t current_read_pos_;
71
72  // Frame header and masking key of the current frame.
73  // |masking_key_| is filled with zeros if the current frame is not masked.
74  scoped_ptr<WebSocketFrameHeader> current_frame_header_;
75  WebSocketMaskingKey masking_key_;
76
77  // Amount of payload data read so far for the current frame.
78  uint64 frame_offset_;
79
80  WebSocketError websocket_error_;
81
82  DISALLOW_COPY_AND_ASSIGN(WebSocketFrameParser);
83};
84
85}  // namespace net
86
87#endif  // NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_
88