blob: 51661255ec8148db42db0085842a95a7e51fcf7d [file] [log] [blame]
// 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 <utility>
#include <vector>
#include "base/big_endian.h"
#include "base/logging.h"
#include "base/memory/scoped_refptr.h"
#include "net/base/io_buffer.h"
#include "net/websockets/websocket_frame.h"
namespace {
const uint8_t kFinalBit = 0x80;
const uint8_t kReserved1Bit = 0x40;
const uint8_t kReserved2Bit = 0x20;
const uint8_t kReserved3Bit = 0x10;
const uint8_t kOpCodeMask = 0xF;
const uint8_t kMaskBit = 0x80;
const uint8_t kPayloadLengthMask = 0x7F;
const uint64_t kMaxPayloadLengthWithoutExtendedLengthField = 125;
const uint64_t kPayloadLengthWithTwoByteExtendedLengthField = 126;
const uint64_t kPayloadLengthWithEightByteExtendedLengthField = 127;
const size_t kMaximumFrameHeaderSize =
net::WebSocketFrameHeader::kBaseHeaderSize +
net::WebSocketFrameHeader::kMaximumExtendedLengthSize +
net::WebSocketFrameHeader::kMaskingKeyLength;
} // namespace.
namespace net {
WebSocketFrameParser::WebSocketFrameParser()
: frame_offset_(0), websocket_error_(kWebSocketNormalClosure) {}
WebSocketFrameParser::~WebSocketFrameParser() = default;
bool WebSocketFrameParser::Decode(
const char* data,
size_t length,
std::vector<std::unique_ptr<WebSocketFrameChunk>>* frame_chunks) {
if (websocket_error_ != kWebSocketNormalClosure)
return false;
if (!length)
return true;
base::span<const char> data_span = base::make_span(data, length);
// If we have incomplete frame header, try to decode a header combining with
// |data|.
bool first_chunk = false;
if (incomplete_header_buffer_.size() > 0) {
DCHECK(!current_frame_header_.get());
const size_t original_size = incomplete_header_buffer_.size();
DCHECK_LE(original_size, kMaximumFrameHeaderSize);
incomplete_header_buffer_.insert(
incomplete_header_buffer_.end(), data,
data + std::min(length, kMaximumFrameHeaderSize - original_size));
const size_t consumed = DecodeFrameHeader(incomplete_header_buffer_);
if (websocket_error_ != kWebSocketNormalClosure)
return false;
if (!current_frame_header_.get())
return true;
DCHECK_GE(consumed, original_size);
data_span = data_span.subspan(consumed - original_size);
incomplete_header_buffer_.clear();
first_chunk = true;
}
DCHECK(incomplete_header_buffer_.empty());
while (data_span.size() > 0 || first_chunk) {
if (!current_frame_header_.get()) {
const size_t consumed = DecodeFrameHeader(data_span);
if (websocket_error_ != kWebSocketNormalClosure)
return false;
// If frame header is incomplete, then carry over the remaining
// data to the next round of Decode().
if (!current_frame_header_.get()) {
DCHECK(!consumed);
incomplete_header_buffer_.insert(incomplete_header_buffer_.end(),
data_span.data(),
data_span.data() + data_span.size());
// Sanity check: the size of carried-over data should not exceed
// the maximum possible length of a frame header.
DCHECK_LT(incomplete_header_buffer_.size(), kMaximumFrameHeaderSize);
return true;
}
DCHECK_GE(data_span.size(), consumed);
data_span = data_span.subspan(consumed);
first_chunk = true;
}
DCHECK(incomplete_header_buffer_.empty());
std::unique_ptr<WebSocketFrameChunk> frame_chunk =
DecodeFramePayload(first_chunk, &data_span);
first_chunk = false;
DCHECK(frame_chunk.get());
frame_chunks->push_back(std::move(frame_chunk));
}
return true;
}
size_t WebSocketFrameParser::DecodeFrameHeader(base::span<const char> data) {
DVLOG(3) << "DecodeFrameHeader buffer size:"
<< ", data size:" << data.size();
typedef WebSocketFrameHeader::OpCode OpCode;
DCHECK(!current_frame_header_.get());
// Header needs 2 bytes at minimum.
if (data.size() < 2)
return 0;
size_t current = 0;
const uint8_t first_byte = data[current++];
const uint8_t second_byte = data[current++];
const bool final = (first_byte & kFinalBit) != 0;
const bool reserved1 = (first_byte & kReserved1Bit) != 0;
const bool reserved2 = (first_byte & kReserved2Bit) != 0;
const bool reserved3 = (first_byte & kReserved3Bit) != 0;
const OpCode opcode = first_byte & kOpCodeMask;
uint64_t payload_length = second_byte & kPayloadLengthMask;
if (payload_length == kPayloadLengthWithTwoByteExtendedLengthField) {
if (data.size() < current + 2)
return 0;
uint16_t payload_length_16;
base::ReadBigEndian(&data[current], &payload_length_16);
current += 2;
payload_length = payload_length_16;
if (payload_length <= kMaxPayloadLengthWithoutExtendedLengthField) {
websocket_error_ = kWebSocketErrorProtocolError;
return 0;
}
} else if (payload_length == kPayloadLengthWithEightByteExtendedLengthField) {
if (data.size() < current + 8)
return 0;
base::ReadBigEndian(&data[current], &payload_length);
current += 8;
if (payload_length <= UINT16_MAX ||
payload_length > static_cast<uint64_t>(INT64_MAX)) {
websocket_error_ = kWebSocketErrorProtocolError;
return 0;
}
if (payload_length > static_cast<uint64_t>(INT32_MAX)) {
websocket_error_ = kWebSocketErrorMessageTooBig;
return 0;
}
}
DCHECK_EQ(websocket_error_, kWebSocketNormalClosure);
WebSocketMaskingKey masking_key = {};
const bool masked = (second_byte & kMaskBit) != 0;
static const int kMaskingKeyLength = WebSocketFrameHeader::kMaskingKeyLength;
if (masked) {
if (data.size() < current + kMaskingKeyLength)
return 0;
std::copy(&data[current], &data[current] + kMaskingKeyLength,
masking_key.key);
current += kMaskingKeyLength;
}
current_frame_header_ = std::make_unique<WebSocketFrameHeader>(opcode);
current_frame_header_->final = final;
current_frame_header_->reserved1 = reserved1;
current_frame_header_->reserved2 = reserved2;
current_frame_header_->reserved3 = reserved3;
current_frame_header_->masked = masked;
current_frame_header_->masking_key = masking_key;
current_frame_header_->payload_length = payload_length;
DCHECK_EQ(0u, frame_offset_);
return current;
}
std::unique_ptr<WebSocketFrameChunk> WebSocketFrameParser::DecodeFramePayload(
bool first_chunk,
base::span<const char>* data) {
// The cast here is safe because |payload_length| is already checked to be
// less than std::numeric_limits<int>::max() when the header is parsed.
const int chunk_data_size = static_cast<int>(
std::min(static_cast<uint64_t>(data->size()),
current_frame_header_->payload_length - frame_offset_));
auto frame_chunk = std::make_unique<WebSocketFrameChunk>();
if (first_chunk) {
frame_chunk->header = current_frame_header_->Clone();
}
frame_chunk->final_chunk = false;
if (chunk_data_size > 0) {
frame_chunk->data = data->subspan(0, chunk_data_size);
*data = data->subspan(chunk_data_size);
frame_offset_ += chunk_data_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;
}
} // namespace net