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// Copyright 2021 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/spdy/alps_decoder.h"
#include <string_view>
#include "base/feature_list.h"
#include "base/metrics/histogram_functions.h"
#include "net/base/features.h"
namespace net {
namespace {
bool ReadUint16PrefixedStringPiece(std::string_view* payload,
std::string_view* output) {
if (payload->size() < 2) {
return false;
}
const uint16_t length = (static_cast<uint16_t>((*payload)[0]) << 8) +
(static_cast<uint8_t>((*payload)[1]));
payload->remove_prefix(2);
if (payload->size() < length) {
return false;
}
*output = payload->substr(0, length);
payload->remove_prefix(length);
return true;
}
} // anonymous namespace
AlpsDecoder::AlpsDecoder() {
decoder_adapter_.set_visitor(&settings_parser_);
decoder_adapter_.set_extension_visitor(&accept_ch_parser_);
}
AlpsDecoder::~AlpsDecoder() = default;
AlpsDecoder::Error AlpsDecoder::Decode(base::span<const char> data) {
decoder_adapter_.ProcessInput(data.data(), data.size());
// Log if any errors were bypassed.
base::UmaHistogramEnumeration(
"Net.SpdySession.AlpsDecoderStatus.Bypassed",
accept_ch_parser_.error_bypass());
if (decoder_adapter_.HasError()) {
return Error::kFramingError;
}
if (settings_parser_.forbidden_frame_received()) {
return Error::kForbiddenFrame;
}
if (settings_parser_.settings_ack_received()) {
return Error::kSettingsWithAck;
}
if (decoder_adapter_.state() !=
http2::Http2DecoderAdapter::SPDY_READY_FOR_FRAME) {
return Error::kNotOnFrameBoundary;
}
return accept_ch_parser_.error();
}
int AlpsDecoder::settings_frame_count() const {
return settings_parser_.settings_frame_count();
}
AlpsDecoder::SettingsParser::SettingsParser() = default;
AlpsDecoder::SettingsParser::~SettingsParser() = default;
void AlpsDecoder::SettingsParser::OnCommonHeader(
spdy::SpdyStreamId /*stream_id*/,
size_t /*length*/,
uint8_t type,
uint8_t /*flags*/) {
if (type == static_cast<uint8_t>(http2::Http2FrameType::DATA) ||
type == static_cast<uint8_t>(http2::Http2FrameType::HEADERS) ||
type == static_cast<uint8_t>(http2::Http2FrameType::PRIORITY) ||
type == static_cast<uint8_t>(http2::Http2FrameType::RST_STREAM) ||
type == static_cast<uint8_t>(http2::Http2FrameType::PUSH_PROMISE) ||
type == static_cast<uint8_t>(http2::Http2FrameType::PING) ||
type == static_cast<uint8_t>(http2::Http2FrameType::GOAWAY) ||
type == static_cast<uint8_t>(http2::Http2FrameType::WINDOW_UPDATE) ||
type == static_cast<uint8_t>(http2::Http2FrameType::CONTINUATION)) {
forbidden_frame_received_ = true;
}
}
void AlpsDecoder::SettingsParser::OnSettings() {
settings_frame_count_++;
}
void AlpsDecoder::SettingsParser::OnSetting(spdy::SpdySettingsId id,
uint32_t value) {
settings_[id] = value;
}
void AlpsDecoder::SettingsParser::OnSettingsAck() {
settings_ack_received_ = true;
}
AlpsDecoder::AcceptChParser::AcceptChParser() = default;
AlpsDecoder::AcceptChParser::~AcceptChParser() = default;
bool AlpsDecoder::AcceptChParser::OnFrameHeader(spdy::SpdyStreamId stream_id,
size_t length,
uint8_t type,
uint8_t flags) {
// Ignore data after an error has occurred.
if (error_ != Error::kNoError)
return false;
// Stop all alps parsing if it's disabled.
if (!base::FeatureList::IsEnabled(features::kAlpsParsing))
return false;
// Handle per-type parsing.
switch (type) {
case static_cast<uint8_t>(spdy::SpdyFrameType::ACCEPT_CH): {
// Stop alps client hint parsing if it's disabled.
if (!base::FeatureList::IsEnabled(features::kAlpsClientHintParsing))
return false;
// Check for issues with the frame.
if (stream_id != 0) {
error_ = Error::kAcceptChInvalidStream;
return false;
}
if (flags != 0) {
error_ = Error::kAcceptChWithFlags;
return false;
}
// This frame can be parsed in OnFramePayload.
return true;
}
default:
// Ignore all other types.
return false;
}
}
void AlpsDecoder::AcceptChParser::OnFramePayload(const char* data, size_t len) {
DCHECK_EQ(Error::kNoError, error_);
std::string_view payload(data, len);
while (!payload.empty()) {
std::string_view origin;
std::string_view value;
if (!ReadUint16PrefixedStringPiece(&payload, &origin) ||
!ReadUint16PrefixedStringPiece(&payload, &value)) {
if (base::FeatureList::IsEnabled(
features::kShouldKillSessionOnAcceptChMalformed)) {
// This causes a session termination.
error_ = Error::kAcceptChMalformed;
return;
} else {
// This logs that a session termination was bypassed.
error_bypass_ = Error::kAcceptChMalformed;
return;
}
}
accept_ch_.push_back(
spdy::AcceptChOriginValuePair{std::string(origin), std::string(value)});
}
}
} // namespace net
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