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/*
* Copyright (C) 2011 Google Inc. All rights reserved.
* Copyright (C) Research In Motion Limited 2011. All rights reserved.
* Copyright (C) 2012 Nokia Corporation and/or its subsidiary(-ies)
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public License
* along with this program; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
* Boston, MA 02110-1301, USA.
*
*/
#include "config.h"
#if ENABLE(WEB_SOCKETS)
#include "WebSocketFrame.h"
#include <wtf/CryptographicallyRandomNumber.h>
#include <wtf/MathExtras.h>
namespace WebCore {
// Constants for hybi-10 frame format.
const unsigned char finalBit = 0x80;
const unsigned char compressBit = 0x40;
const unsigned char reserved2Bit = 0x20;
const unsigned char reserved3Bit = 0x10;
const unsigned char opCodeMask = 0xF;
const unsigned char maskBit = 0x80;
const unsigned char payloadLengthMask = 0x7F;
const size_t maxPayloadLengthWithoutExtendedLengthField = 125;
const size_t payloadLengthWithTwoByteExtendedLengthField = 126;
const size_t payloadLengthWithEightByteExtendedLengthField = 127;
const size_t maskingKeyWidthInBytes = 4;
bool WebSocketFrame::needsExtendedLengthField(size_t payloadLength)
{
return payloadLength > maxPayloadLengthWithoutExtendedLengthField;
}
WebSocketFrame::ParseFrameResult WebSocketFrame::parseFrame(char* data, size_t dataLength, WebSocketFrame& frame, const char*& frameEnd, String& errorString)
{
char* p = data;
const char* bufferEnd = data + dataLength;
if (dataLength < 2)
return FrameIncomplete;
unsigned char firstByte = *p++;
unsigned char secondByte = *p++;
bool final = firstByte & finalBit;
bool compress = firstByte & compressBit;
bool reserved2 = firstByte & reserved2Bit;
bool reserved3 = firstByte & reserved3Bit;
unsigned char opCode = firstByte & opCodeMask;
bool masked = secondByte & maskBit;
uint64_t payloadLength64 = secondByte & payloadLengthMask;
if (payloadLength64 > maxPayloadLengthWithoutExtendedLengthField) {
int extendedPayloadLengthSize;
if (payloadLength64 == payloadLengthWithTwoByteExtendedLengthField)
extendedPayloadLengthSize = 2;
else {
ASSERT(payloadLength64 == payloadLengthWithEightByteExtendedLengthField);
extendedPayloadLengthSize = 8;
}
if (bufferEnd - p < extendedPayloadLengthSize)
return FrameIncomplete;
payloadLength64 = 0;
for (int i = 0; i < extendedPayloadLengthSize; ++i) {
payloadLength64 <<= 8;
payloadLength64 |= static_cast<unsigned char>(*p++);
}
if (extendedPayloadLengthSize == 2 && payloadLength64 <= maxPayloadLengthWithoutExtendedLengthField) {
errorString = "The minimal number of bytes MUST be used to encode the length";
return FrameError;
}
if (extendedPayloadLengthSize == 8 && payloadLength64 <= 0xFFFF) {
errorString = "The minimal number of bytes MUST be used to encode the length";
return FrameError;
}
}
static const uint64_t maxPayloadLength = UINT64_C(0x7FFFFFFFFFFFFFFF);
size_t maskingKeyLength = masked ? maskingKeyWidthInBytes : 0;
if (payloadLength64 > maxPayloadLength || payloadLength64 + maskingKeyLength > std::numeric_limits<size_t>::max()) {
errorString = "WebSocket frame length too large: " + String::number(payloadLength64) + " bytes";
return FrameError;
}
size_t payloadLength = static_cast<size_t>(payloadLength64);
if (static_cast<size_t>(bufferEnd - p) < maskingKeyLength + payloadLength)
return FrameIncomplete;
if (masked) {
const char* maskingKey = p;
char* payload = p + maskingKeyWidthInBytes;
for (size_t i = 0; i < payloadLength; ++i)
payload[i] ^= maskingKey[i % maskingKeyWidthInBytes]; // Unmask the payload.
}
frame.opCode = static_cast<WebSocketFrame::OpCode>(opCode);
frame.final = final;
frame.compress = compress;
frame.reserved2 = reserved2;
frame.reserved3 = reserved3;
frame.masked = masked;
frame.payload = p + maskingKeyLength;
frame.payloadLength = payloadLength;
frameEnd = p + maskingKeyLength + payloadLength;
return FrameOK;
}
static void appendFramePayload(const WebSocketFrame& frame, Vector<char>& frameData)
{
size_t maskingKeyStart = 0;
if (frame.masked) {
maskingKeyStart = frameData.size();
frameData.grow(frameData.size() + maskingKeyWidthInBytes); // Add placeholder for masking key. Will be overwritten.
}
size_t payloadStart = frameData.size();
frameData.append(frame.payload, frame.payloadLength);
if (frame.masked) {
cryptographicallyRandomValues(frameData.data() + maskingKeyStart, maskingKeyWidthInBytes);
for (size_t i = 0; i < frame.payloadLength; ++i)
frameData[payloadStart + i] ^= frameData[maskingKeyStart + i % maskingKeyWidthInBytes];
}
}
void WebSocketFrame::makeFrameData(Vector<char>& frameData)
{
ASSERT(!(opCode & ~opCodeMask)); // Checks whether "opCode" fits in the range of opCodes.
frameData.resize(2);
frameData.at(0) = (final ? finalBit : 0) | (compress ? compressBit : 0) | opCode;
frameData.at(1) = masked ? maskBit : 0;
if (payloadLength <= maxPayloadLengthWithoutExtendedLengthField)
frameData.at(1) |= payloadLength;
else if (payloadLength <= 0xFFFF) {
frameData.at(1) |= payloadLengthWithTwoByteExtendedLengthField;
frameData.append((payloadLength & 0xFF00) >> 8);
frameData.append(payloadLength & 0xFF);
} else {
frameData.at(1) |= payloadLengthWithEightByteExtendedLengthField;
char extendedPayloadLength[8];
size_t remaining = payloadLength;
// Fill the length into extendedPayloadLength in the network byte order.
for (int i = 0; i < 8; ++i) {
extendedPayloadLength[7 - i] = remaining & 0xFF;
remaining >>= 8;
}
ASSERT(!remaining);
frameData.append(extendedPayloadLength, 8);
}
appendFramePayload(*this, frameData);
}
WebSocketFrame::WebSocketFrame(OpCode opCode, bool final, bool compress, bool masked, const char* payload, size_t payloadLength)
: opCode(opCode)
, final(final)
, compress(compress)
, reserved2(false)
, reserved3(false)
, masked(masked)
, payload(payload)
, payloadLength(payloadLength)
{
}
} // namespace WebCore
#endif // ENABLE(WEB_SOCKETS)
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