blob: ac07fedff615a994065dd71f3c75034e4f2b546e [file] [log] [blame]
// Copyright (c) 2018 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 "quic/core/qpack/qpack_progressive_decoder.h"
#include <algorithm>
#include <limits>
#include <utility>
#include "absl/strings/string_view.h"
#include "quic/core/qpack/qpack_index_conversions.h"
#include "quic/core/qpack/qpack_instructions.h"
#include "quic/core/qpack/qpack_required_insert_count.h"
#include "quic/platform/api/quic_logging.h"
namespace quic {
QpackProgressiveDecoder::QpackProgressiveDecoder(
QuicStreamId stream_id,
BlockedStreamLimitEnforcer* enforcer,
DecodingCompletedVisitor* visitor,
QpackHeaderTable* header_table,
HeadersHandlerInterface* handler)
: stream_id_(stream_id),
prefix_decoder_(
std::make_unique<QpackInstructionDecoder>(QpackPrefixLanguage(),
this)),
instruction_decoder_(QpackRequestStreamLanguage(), this),
enforcer_(enforcer),
visitor_(visitor),
header_table_(header_table),
handler_(handler),
required_insert_count_(0),
base_(0),
required_insert_count_so_far_(0),
prefix_decoded_(false),
blocked_(false),
decoding_(true),
error_detected_(false),
cancelled_(false) {}
QpackProgressiveDecoder::~QpackProgressiveDecoder() {
if (blocked_ && !cancelled_) {
header_table_->UnregisterObserver(required_insert_count_, this);
}
}
void QpackProgressiveDecoder::Decode(absl::string_view data) {
QUICHE_DCHECK(decoding_);
if (data.empty() || error_detected_) {
return;
}
// Decode prefix byte by byte until the first (and only) instruction is
// decoded.
while (!prefix_decoded_) {
QUICHE_DCHECK(!blocked_);
if (!prefix_decoder_->Decode(data.substr(0, 1))) {
return;
}
// |prefix_decoder_->Decode()| must return false if an error is detected.
QUICHE_DCHECK(!error_detected_);
data = data.substr(1);
if (data.empty()) {
return;
}
}
if (blocked_) {
buffer_.append(data.data(), data.size());
} else {
QUICHE_DCHECK(buffer_.empty());
instruction_decoder_.Decode(data);
}
}
void QpackProgressiveDecoder::EndHeaderBlock() {
QUICHE_DCHECK(decoding_);
decoding_ = false;
if (!blocked_) {
FinishDecoding();
}
}
void QpackProgressiveDecoder::OnError(absl::string_view error_message) {
QUICHE_DCHECK(!error_detected_);
error_detected_ = true;
// Might destroy |this|.
handler_->OnDecodingErrorDetected(error_message);
}
bool QpackProgressiveDecoder::OnInstructionDecoded(
const QpackInstruction* instruction) {
if (instruction == QpackPrefixInstruction()) {
return DoPrefixInstruction();
}
QUICHE_DCHECK(prefix_decoded_);
QUICHE_DCHECK_LE(required_insert_count_,
header_table_->inserted_entry_count());
if (instruction == QpackIndexedHeaderFieldInstruction()) {
return DoIndexedHeaderFieldInstruction();
}
if (instruction == QpackIndexedHeaderFieldPostBaseInstruction()) {
return DoIndexedHeaderFieldPostBaseInstruction();
}
if (instruction == QpackLiteralHeaderFieldNameReferenceInstruction()) {
return DoLiteralHeaderFieldNameReferenceInstruction();
}
if (instruction == QpackLiteralHeaderFieldPostBaseInstruction()) {
return DoLiteralHeaderFieldPostBaseInstruction();
}
QUICHE_DCHECK_EQ(instruction, QpackLiteralHeaderFieldInstruction());
return DoLiteralHeaderFieldInstruction();
}
void QpackProgressiveDecoder::OnInstructionDecodingError(
QpackInstructionDecoder::ErrorCode /* error_code */,
absl::string_view error_message) {
// Ignore |error_code|, because header block decoding errors trigger a
// RESET_STREAM frame which cannot carry an error code more granular than
// QPACK_DECOMPRESSION_FAILED.
OnError(error_message);
}
void QpackProgressiveDecoder::OnInsertCountReachedThreshold() {
QUICHE_DCHECK(blocked_);
// Clear |blocked_| before calling instruction_decoder_.Decode() below,
// because that might destroy |this| and ~QpackProgressiveDecoder() needs to
// know not to call UnregisterObserver().
blocked_ = false;
enforcer_->OnStreamUnblocked(stream_id_);
if (!buffer_.empty()) {
std::string buffer(std::move(buffer_));
buffer_.clear();
if (!instruction_decoder_.Decode(buffer)) {
// |this| might be destroyed.
return;
}
}
if (!decoding_) {
FinishDecoding();
}
}
void QpackProgressiveDecoder::Cancel() {
cancelled_ = true;
}
bool QpackProgressiveDecoder::DoIndexedHeaderFieldInstruction() {
if (!instruction_decoder_.s_bit()) {
uint64_t absolute_index;
if (!QpackRequestStreamRelativeIndexToAbsoluteIndex(
instruction_decoder_.varint(), base_, &absolute_index)) {
OnError("Invalid relative index.");
return false;
}
if (absolute_index >= required_insert_count_) {
OnError("Absolute Index must be smaller than Required Insert Count.");
return false;
}
QUICHE_DCHECK_LT(absolute_index, std::numeric_limits<uint64_t>::max());
required_insert_count_so_far_ =
std::max(required_insert_count_so_far_, absolute_index + 1);
auto entry =
header_table_->LookupEntry(/* is_static = */ false, absolute_index);
if (!entry) {
OnError("Dynamic table entry already evicted.");
return false;
}
header_table_->set_dynamic_table_entry_referenced();
handler_->OnHeaderDecoded(entry->name(), entry->value());
return true;
}
auto entry = header_table_->LookupEntry(/* is_static = */ true,
instruction_decoder_.varint());
if (!entry) {
OnError("Static table entry not found.");
return false;
}
handler_->OnHeaderDecoded(entry->name(), entry->value());
return true;
}
bool QpackProgressiveDecoder::DoIndexedHeaderFieldPostBaseInstruction() {
uint64_t absolute_index;
if (!QpackPostBaseIndexToAbsoluteIndex(instruction_decoder_.varint(), base_,
&absolute_index)) {
OnError("Invalid post-base index.");
return false;
}
if (absolute_index >= required_insert_count_) {
OnError("Absolute Index must be smaller than Required Insert Count.");
return false;
}
QUICHE_DCHECK_LT(absolute_index, std::numeric_limits<uint64_t>::max());
required_insert_count_so_far_ =
std::max(required_insert_count_so_far_, absolute_index + 1);
auto entry =
header_table_->LookupEntry(/* is_static = */ false, absolute_index);
if (!entry) {
OnError("Dynamic table entry already evicted.");
return false;
}
header_table_->set_dynamic_table_entry_referenced();
handler_->OnHeaderDecoded(entry->name(), entry->value());
return true;
}
bool QpackProgressiveDecoder::DoLiteralHeaderFieldNameReferenceInstruction() {
if (!instruction_decoder_.s_bit()) {
uint64_t absolute_index;
if (!QpackRequestStreamRelativeIndexToAbsoluteIndex(
instruction_decoder_.varint(), base_, &absolute_index)) {
OnError("Invalid relative index.");
return false;
}
if (absolute_index >= required_insert_count_) {
OnError("Absolute Index must be smaller than Required Insert Count.");
return false;
}
QUICHE_DCHECK_LT(absolute_index, std::numeric_limits<uint64_t>::max());
required_insert_count_so_far_ =
std::max(required_insert_count_so_far_, absolute_index + 1);
auto entry =
header_table_->LookupEntry(/* is_static = */ false, absolute_index);
if (!entry) {
OnError("Dynamic table entry already evicted.");
return false;
}
header_table_->set_dynamic_table_entry_referenced();
handler_->OnHeaderDecoded(entry->name(), instruction_decoder_.value());
return true;
}
auto entry = header_table_->LookupEntry(/* is_static = */ true,
instruction_decoder_.varint());
if (!entry) {
OnError("Static table entry not found.");
return false;
}
handler_->OnHeaderDecoded(entry->name(), instruction_decoder_.value());
return true;
}
bool QpackProgressiveDecoder::DoLiteralHeaderFieldPostBaseInstruction() {
uint64_t absolute_index;
if (!QpackPostBaseIndexToAbsoluteIndex(instruction_decoder_.varint(), base_,
&absolute_index)) {
OnError("Invalid post-base index.");
return false;
}
if (absolute_index >= required_insert_count_) {
OnError("Absolute Index must be smaller than Required Insert Count.");
return false;
}
QUICHE_DCHECK_LT(absolute_index, std::numeric_limits<uint64_t>::max());
required_insert_count_so_far_ =
std::max(required_insert_count_so_far_, absolute_index + 1);
auto entry =
header_table_->LookupEntry(/* is_static = */ false, absolute_index);
if (!entry) {
OnError("Dynamic table entry already evicted.");
return false;
}
header_table_->set_dynamic_table_entry_referenced();
handler_->OnHeaderDecoded(entry->name(), instruction_decoder_.value());
return true;
}
bool QpackProgressiveDecoder::DoLiteralHeaderFieldInstruction() {
handler_->OnHeaderDecoded(instruction_decoder_.name(),
instruction_decoder_.value());
return true;
}
bool QpackProgressiveDecoder::DoPrefixInstruction() {
QUICHE_DCHECK(!prefix_decoded_);
if (!QpackDecodeRequiredInsertCount(
prefix_decoder_->varint(), header_table_->max_entries(),
header_table_->inserted_entry_count(), &required_insert_count_)) {
OnError("Error decoding Required Insert Count.");
return false;
}
const bool sign = prefix_decoder_->s_bit();
const uint64_t delta_base = prefix_decoder_->varint2();
if (!DeltaBaseToBase(sign, delta_base, &base_)) {
OnError("Error calculating Base.");
return false;
}
prefix_decoded_ = true;
if (required_insert_count_ > header_table_->inserted_entry_count()) {
if (!enforcer_->OnStreamBlocked(stream_id_)) {
OnError("Limit on number of blocked streams exceeded.");
return false;
}
blocked_ = true;
header_table_->RegisterObserver(required_insert_count_, this);
}
return true;
}
void QpackProgressiveDecoder::FinishDecoding() {
QUICHE_DCHECK(buffer_.empty());
QUICHE_DCHECK(!blocked_);
QUICHE_DCHECK(!decoding_);
if (error_detected_) {
return;
}
if (!instruction_decoder_.AtInstructionBoundary()) {
OnError("Incomplete header block.");
return;
}
if (!prefix_decoded_) {
OnError("Incomplete header data prefix.");
return;
}
if (required_insert_count_ != required_insert_count_so_far_) {
OnError("Required Insert Count too large.");
return;
}
visitor_->OnDecodingCompleted(stream_id_, required_insert_count_);
handler_->OnDecodingCompleted();
}
bool QpackProgressiveDecoder::DeltaBaseToBase(bool sign,
uint64_t delta_base,
uint64_t* base) {
if (sign) {
if (delta_base == std::numeric_limits<uint64_t>::max() ||
required_insert_count_ < delta_base + 1) {
return false;
}
*base = required_insert_count_ - delta_base - 1;
return true;
}
if (delta_base >
std::numeric_limits<uint64_t>::max() - required_insert_count_) {
return false;
}
*base = required_insert_count_ + delta_base;
return true;
}
} // namespace quic