Add WebSocketFrameParser.

net/websockets/websocket_frame_parser.h

+// Copyright (c) 2012 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_FRAME_PARSER_H_
+#define NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_
+#pragma once
+
+#include <vector>
+
+#include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
+#include "base/memory/scoped_vector.h"
+#include "net/base/net_export.h"
+#include "net/websockets/websocket_frame.h"
+
+namespace net {
+
+// Parses WebSocket frames from byte stream.
+//
+// Specification of WebSocket frame format is available at
+// <http://tools.ietf.org/html/rfc6455#section-5>.
+
+class NET_EXPORT_PRIVATE WebSocketFrameParser {
+ public:
+  WebSocketFrameParser();
+  ~WebSocketFrameParser();
+
+  // Decodes the given byte stream and stores parsed WebSocket frames in
+  // |frames|.
+  //
+  // If the parser encounters invalid payload length format, Decode() fails
+  // and returns false. Once Decode() has failed, the parser refuses to decode
+  // any more data and future invocations of Decode() will simply return false.
+  //
+  // Payload data of parsed WebSocket frames may be incomplete; see comments in
+  // websocket_frame.h for more details.
+  bool Decode(const char* data,
+              size_t length,
+              ScopedVector<WebSocketPartialFrame>* frames);
+
+  // Returns true if the parser has ever failed to decode a WebSocket frame.
+  // TODO(yutak): Provide human-readable description of failure.
+  bool failed() const { return failed_; }
+
+ private:
+  // Tries to decode a frame header from |current_read_pos_|.
+  // If successful, this function updates |current_read_pos_|,
+  // |current_frame_header_|, and |masking_key_| (if available).
+  // This function may set |failed_| to true if it observes a corrupt frame.
+  // If there is not enough data in the remaining buffer to parse a frame
+  // header, this function returns without doing anything.
+  void DecodeFrameHeader();
+
+  // Decodes frame payload and creates a WebSocketPartialFrame object.
+  // This function updates |current_read_pos_| and |frame_offset_| after
+  // parsing. This function returns a frame object even if no payload data is
+  // available at this moment, so the receiver could make use of frame header
+  // information. If the end of frame is reached, this function clears
+  // |current_frame_header_|, |frame_offset_| and |masking_key_|.
+  scoped_ptr<WebSocketPartialFrame> DecodeFramePayload();
+
+  // Internal buffer to store the data to parse.
+  std::vector<char> buffer_;
+
+  // Position in |buffer_| where the next round of parsing starts.
+  size_t current_read_pos_;
+
+  // Frame header and masking key of the current frame.
+  // |masking_key_| is filled with zeros if the current frame is not masked.
+  scoped_refptr<WebSocketFrameHeader> current_frame_header_;
+  char masking_key_[WebSocketFrameHeader::kMaskingKeyLength];
+
+  // Amount of payload data read so far for the current frame.
+  uint64 frame_offset_;
+
+  bool failed_;
+};
+
+}  // namespace net
+
+#endif  // NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_