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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 "net/websockets/websocket_frame_parser.h"
#include <algorithm>
#include <limits>
#include "base/basictypes.h"
#include "base/logging.h"
#include "base/memory/ref_counted.h"
#include "base/memory/scoped_ptr.h"
#include "base/memory/scoped_vector.h"
#include "net/base/big_endian.h"
#include "net/base/io_buffer.h"
#include "net/websockets/websocket_frame.h"
namespace {
const uint8 kFinalBit = 0x80;
const uint8 kReserved1Bit = 0x40;
const uint8 kReserved2Bit = 0x20;
const uint8 kReserved3Bit = 0x10;
const uint8 kOpCodeMask = 0xF;
const uint8 kMaskBit = 0x80;
const uint8 kPayloadLengthMask = 0x7F;
const uint64 kMaxPayloadLengthWithoutExtendedLengthField = 125;
const uint64 kPayloadLengthWithTwoByteExtendedLengthField = 126;
const uint64 kPayloadLengthWithEightByteExtendedLengthField = 127;
} // Unnamed namespace.
namespace net {
WebSocketFrameParser::WebSocketFrameParser()
: current_read_pos_(0),
frame_offset_(0),
failed_(false) {
std::fill(masking_key_,
masking_key_ + WebSocketFrameHeader::kMaskingKeyLength,
'\0');
}
WebSocketFrameParser::~WebSocketFrameParser() {
}
bool WebSocketFrameParser::Decode(
const char* data,
size_t length,
ScopedVector<WebSocketFrameChunk>* frame_chunks) {
if (failed_)
return false;
if (!length)
return true;
// TODO(yutak): Remove copy.
buffer_.insert(buffer_.end(), data, data + length);
while (current_read_pos_ < buffer_.size()) {
bool first_chunk = false;
if (!current_frame_header_.get()) {
DecodeFrameHeader();
if (failed_)
return false;
// If frame header is incomplete, then carry over the remaining
// data to the next round of Decode().
if (!current_frame_header_.get())
break;
first_chunk = true;
}
scoped_ptr<WebSocketFrameChunk> frame_chunk =
DecodeFramePayload(first_chunk);
DCHECK(frame_chunk.get());
frame_chunks->push_back(frame_chunk.release());
if (current_frame_header_.get()) {
DCHECK(current_read_pos_ == buffer_.size());
break;
}
}
// Drain unnecessary data. TODO(yutak): Remove copy. (but how?)
buffer_.erase(buffer_.begin(), buffer_.begin() + current_read_pos_);
current_read_pos_ = 0;
// Sanity check: the size of carried-over data should not exceed
// the maximum possible length of a frame header.
static const size_t kMaximumFrameHeaderSize =
WebSocketFrameHeader::kBaseHeaderSize +
WebSocketFrameHeader::kMaximumExtendedLengthSize +
WebSocketFrameHeader::kMaskingKeyLength;
DCHECK_LT(buffer_.size(), kMaximumFrameHeaderSize);
return true;
}
void WebSocketFrameParser::DecodeFrameHeader() {
typedef WebSocketFrameHeader::OpCode OpCode;
static const int kMaskingKeyLength = WebSocketFrameHeader::kMaskingKeyLength;
DCHECK(!current_frame_header_.get());
const char* start = &buffer_.front() + current_read_pos_;
const char* current = start;
const char* end = &buffer_.front() + buffer_.size();
// Header needs 2 bytes at minimum.
if (end - current < 2)
return;
uint8 first_byte = *current++;
uint8 second_byte = *current++;
bool final = (first_byte & kFinalBit) != 0;
bool reserved1 = (first_byte & kReserved1Bit) != 0;
bool reserved2 = (first_byte & kReserved2Bit) != 0;
bool reserved3 = (first_byte & kReserved3Bit) != 0;
OpCode opcode = first_byte & kOpCodeMask;
bool masked = (second_byte & kMaskBit) != 0;
uint64 payload_length = second_byte & kPayloadLengthMask;
bool valid_length_format = true;
bool message_too_big = false;
if (payload_length == kPayloadLengthWithTwoByteExtendedLengthField) {
if (end - current < 2)
return;
uint16 payload_length_16;
ReadBigEndian(current, &payload_length_16);
current += 2;
payload_length = payload_length_16;
if (payload_length <= kMaxPayloadLengthWithoutExtendedLengthField)
valid_length_format = false;
} else if (payload_length == kPayloadLengthWithEightByteExtendedLengthField) {
if (end - current < 8)
return;
ReadBigEndian(current, &payload_length);
current += 8;
if (payload_length <= kuint16max ||
payload_length > static_cast<uint64>(kint64max)) {
valid_length_format = false;
}
if (payload_length > static_cast<uint64>(kint32max))
message_too_big = true;
}
if (!valid_length_format || message_too_big) {
failed_ = true;
buffer_.clear();
current_read_pos_ = 0;
current_frame_header_.reset();
frame_offset_ = 0;
return;
}
if (masked) {
if (end - current < kMaskingKeyLength)
return;
std::copy(current, current + kMaskingKeyLength, masking_key_);
current += kMaskingKeyLength;
} else {
std::fill(masking_key_, masking_key_ + kMaskingKeyLength, '\0');
}
current_frame_header_.reset(new WebSocketFrameHeader);
current_frame_header_->final = final;
current_frame_header_->reserved1 = reserved1;
current_frame_header_->reserved2 = reserved2;
current_frame_header_->reserved3 = reserved3;
current_frame_header_->opcode = opcode;
current_frame_header_->masked = masked;
current_frame_header_->payload_length = payload_length;
current_read_pos_ += current - start;
DCHECK_EQ(0u, frame_offset_);
}
scoped_ptr<WebSocketFrameChunk> WebSocketFrameParser::DecodeFramePayload(
bool first_chunk) {
static const int kMaskingKeyLength = WebSocketFrameHeader::kMaskingKeyLength;
const char* current = &buffer_.front() + current_read_pos_;
const char* end = &buffer_.front() + buffer_.size();
uint64 next_size = std::min<uint64>(
end - current,
current_frame_header_->payload_length - frame_offset_);
// This check must pass because |payload_length| is already checked to be
// less than std::numeric_limits<int>::max() when the header is parsed.
DCHECK_LE(next_size, static_cast<uint64>(kint32max));
scoped_ptr<WebSocketFrameChunk> frame_chunk(new WebSocketFrameChunk);
if (first_chunk) {
frame_chunk->header.reset(new WebSocketFrameHeader(*current_frame_header_));
}
frame_chunk->final_chunk = false;
if (next_size) {
frame_chunk->data = new IOBufferWithSize(static_cast<int>(next_size));
char* io_data = frame_chunk->data->data();
memcpy(io_data, current, next_size);
if (current_frame_header_->masked) {
// Unmask the payload.
// TODO(yutak): This could be faster by doing unmasking for each
// machine word (instead of each byte).
size_t key_offset = frame_offset_ % kMaskingKeyLength;
for (uint64 i = 0; i < next_size; ++i) {
io_data[i] ^= masking_key_[key_offset];
key_offset = (key_offset + 1) % kMaskingKeyLength;
}
}
current_read_pos_ += next_size;
frame_offset_ += next_size;
}
DCHECK_LE(frame_offset_, current_frame_header_->payload_length);
if (frame_offset_ == current_frame_header_->payload_length) {
frame_chunk->final_chunk = true;
current_frame_header_.reset();
frame_offset_ = 0;
}
return frame_chunk.Pass();
}
} // namespace net
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