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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.
#include <stdint.h>
#include <memory>
#include <vector>
#include "base/macros.h"
#include "base/memory/scoped_refptr.h"
#include "net/base/net_export.h"
namespace net {
class IOBuffer;
class IOBufferWithSize;
// Represents a WebSocket frame header.
// Members of this class correspond to each element in WebSocket frame header
// (see
struct NET_EXPORT WebSocketFrameHeader {
typedef int OpCode;
// Originally these constants were static const int, but to make it possible
// to use them in a switch statement they were changed to an enum.
enum OpCodeEnum {
kOpCodeContinuation = 0x0,
kOpCodeText = 0x1,
kOpCodeBinary = 0x2,
kOpCodeDataUnused = 0x3,
kOpCodeClose = 0x8,
kOpCodePing = 0x9,
kOpCodePong = 0xA,
kOpCodeControlUnused = 0xB,
// Return true if |opcode| is one of the data opcodes known to this
// implementation.
static bool IsKnownDataOpCode(OpCode opcode) {
return opcode == kOpCodeContinuation || opcode == kOpCodeText ||
opcode == kOpCodeBinary;
// Return true if |opcode| is one of the control opcodes known to this
// implementation.
static bool IsKnownControlOpCode(OpCode opcode) {
return opcode == kOpCodeClose || opcode == kOpCodePing ||
opcode == kOpCodePong;
// These values must be a compile-time constant. "enum hack" is used here
// to make MSVC happy.
enum {
kBaseHeaderSize = 2,
kMaximumExtendedLengthSize = 8,
kMaskingKeyLength = 4
// Constructor to avoid a lot of repetitive initialisation.
explicit WebSocketFrameHeader(OpCode opCode)
: final(false),
payload_length(0) {}
// Create a clone of this object on the heap.
std::unique_ptr<WebSocketFrameHeader> Clone() const;
// Overwrite this object with the fields from |source|.
void CopyFrom(const WebSocketFrameHeader& source);
// Members below correspond to each item in WebSocket frame header.
// See <> for details.
bool final;
bool reserved1;
bool reserved2;
bool reserved3;
OpCode opcode;
bool masked;
uint64_t payload_length;
// 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 {
// A frame must always have an opcode, so this parameter is compulsory.
explicit WebSocketFrame(WebSocketFrameHeader::OpCode opcode);
// |header| is always present.
WebSocketFrameHeader header;
// |data| is always unmasked even if the frame is masked. The size of |data|
// is given by |header.payload_length|.
scoped_refptr<IOBuffer> data;
// 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 {
// Non-null |header| is provided only if this chunk is the first part of
// a series of chunks.
std::unique_ptr<WebSocketFrameHeader> header;
// Indicates this part is the last chunk of a frame.
bool final_chunk;
// |data| is always unmasked even if the frame is masked. |data| might be
// null in the first chunk.
scoped_refptr<IOBufferWithSize> data;
// Contains four-byte data representing "masking key" of WebSocket frames.
struct WebSocketMaskingKey {
char key[WebSocketFrameHeader::kMaskingKeyLength];
// 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 int 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:
// <>. 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,
char* buffer,
int buffer_size);
// 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,
char* data,
int data_size);
} // namespace net