websocket_frame.h | Explore in Territory

// Copyright 2012 The Chromium Authors
// 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_H_
#define NET_WEBSOCKETS_WEBSOCKET_FRAME_H_

#include <stddef.h>
#include <stdint.h>

#include <array>
#include <memory>
#include <vector>

#include "base/containers/span.h"
#include "base/memory/scoped_refptr.h"
#include "net/base/net_export.h"

namespace net {

// Represents a WebSocket frame header.
//
// Members of this class correspond to each element in WebSocket frame header
// (see http://tools.ietf.org/html/rfc6455#section-5.2).
struct NET_EXPORT WebSocketFrameHeader { … };

// Contains an entire WebSocket frame including payload. This is used by APIs
// that are not concerned about retaining the original frame boundaries (because
// frames may need to be split in order for the data to fit in memory).
struct NET_EXPORT_PRIVATE WebSocketFrame { … };

// Structure describing one chunk of a WebSocket frame.
//
// The payload of a WebSocket frame may be divided into multiple chunks.
// You need to look at |final_chunk| member variable to detect the end of a
// series of chunk objects of a WebSocket frame.
//
// Frame dissection is necessary to handle frames that are too large to store in
// the browser memory without losing information about the frame boundaries. In
// practice, most code does not need to worry about the original frame
// boundaries and can use the WebSocketFrame type declared above.
//
// Users of this struct should treat WebSocket frames as a data stream; it's
// important to keep the frame data flowing, especially in the browser process.
// Users should not let the data stuck somewhere in the pipeline.
//
// This struct is used for reading WebSocket frame data (created by
// WebSocketFrameParser). To construct WebSocket frames, use functions below.
struct NET_EXPORT WebSocketFrameChunk { … };

WebSocketMaskingKey;

// Returns the size of WebSocket frame header. The size of WebSocket frame
// header varies from 2 bytes to 14 bytes depending on the payload length
// and maskedness.
NET_EXPORT size_t
GetWebSocketFrameHeaderSize(const WebSocketFrameHeader& header);

// Writes wire format of a WebSocket frame header into |output|, and returns
// the number of bytes written.
//
// WebSocket frame format is defined at:
// <http://tools.ietf.org/html/rfc6455#section-5.2>. This function writes
// everything but payload data in a WebSocket frame to |buffer|.
//
// If |header->masked| is true, |masking_key| must point to a valid
// WebSocketMaskingKey object containing the masking key for that frame
// (possibly generated by GenerateWebSocketMaskingKey() function below).
// Otherwise, |masking_key| must be NULL.
//
// |buffer| should have enough size to contain the frame header.
// GetWebSocketFrameHeaderSize() can be used to know the size of header
// beforehand. If the size of |buffer| is insufficient, this function returns
// ERR_INVALID_ARGUMENT and does not write any data to |buffer|.
NET_EXPORT int WriteWebSocketFrameHeader(const WebSocketFrameHeader& header,
                                         const WebSocketMaskingKey* masking_key,
                                         base::span<uint8_t> buffer);

// Generates a masking key suitable for use in a new WebSocket frame.
NET_EXPORT WebSocketMaskingKey GenerateWebSocketMaskingKey();

// Masks WebSocket frame payload.
//
// A client must mask every WebSocket frame by XOR'ing the frame payload
// with four-byte random data (masking key). This function applies the masking
// to the given payload data.
//
// This function masks |data| with |masking_key|, assuming |data| is partial
// data starting from |frame_offset| bytes from the beginning of the payload
// data.
//
// Since frame masking is a reversible operation, this function can also be
// used for unmasking a WebSocket frame.
NET_EXPORT void MaskWebSocketFramePayload(
    const WebSocketMaskingKey& masking_key,
    uint64_t frame_offset,
    base::span<uint8_t> data);

}  // namespace net

#endif  // NET_WEBSOCKETS_WEBSOCKET_FRAME_H_
chromium/net/websockets/websocket_frame.h
