net/websockets/websocket_frame_parser.h

   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
  18 namespace 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
  25 class 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_