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// 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_
#include <stddef.h>
#include <stdint.h>
#include <memory>
#include <vector>
#include "base/containers/span.h"
#include "base/macros.h"
#include "net/base/net_export.h"
#include "net/websockets/websocket_errors.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>.
// This class does *NOT* unmask frame payload.
class NET_EXPORT WebSocketFrameParser {
public:
WebSocketFrameParser();
~WebSocketFrameParser();
// Decodes the given byte stream and stores parsed WebSocket frames in
// |frame_chunks|.
// Each WebSocketFrameChunk's payload is a subspan of [data, data + length).
// Thus callers must take care of its lifecycle.
//
// 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,
std::vector<std::unique_ptr<WebSocketFrameChunk>>* frame_chunks);
// Returns kWebSocketNormalClosure if the parser has not failed to decode
// WebSocket frames. Otherwise returns WebSocketError which is defined in
// websocket_errors.h. We can convert net::WebSocketError to net::Error by
// using WebSocketErrorToNetError().
WebSocketError websocket_error() const { return websocket_error_; }
private:
// Tries to decode a frame header from |data|.
// If successful, this function updates
// |current_frame_header_|, and |masking_key_| (if available) and returns
// the number of consumed bytes in |data|.
// If there is not enough data in the remaining buffer to parse a frame
// header, this function returns 0 without doing anything.
// This function may update |websocket_error_| if it observes a corrupt frame.
size_t DecodeFrameHeader(base::span<const char> data);
// Decodes frame payload and creates a WebSocketFrameChunk object.
// This function updates |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_|.
std::unique_ptr<WebSocketFrameChunk> DecodeFramePayload(
bool first_chunk,
base::span<const char>* data);
// Internal buffer to store the data to parse header.
std::vector<char> incomplete_header_buffer_;
// Frame header and masking key of the current frame.
// |masking_key_| is filled with zeros if the current frame is not masked.
std::unique_ptr<WebSocketFrameHeader> current_frame_header_;
// Amount of payload data read so far for the current frame.
uint64_t frame_offset_;
WebSocketError websocket_error_;
DISALLOW_COPY_AND_ASSIGN(WebSocketFrameParser);
};
} // namespace net
#endif // NET_WEBSOCKETS_WEBSOCKET_FRAME_PARSER_H_
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