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// Copyright 2016 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/third_party/quiche/src/http2/decoder/payload_decoders/headers_payload_decoder.h"
#include <stddef.h>
#include "base/logging.h"
#include "base/macros.h"
#include "net/third_party/quiche/src/http2/decoder/decode_buffer.h"
#include "net/third_party/quiche/src/http2/decoder/http2_frame_decoder_listener.h"
#include "net/third_party/quiche/src/http2/http2_constants.h"
#include "net/third_party/quiche/src/http2/http2_structures.h"
#include "net/third_party/quiche/src/http2/platform/api/http2_bug_tracker.h"
#include "net/third_party/quiche/src/http2/platform/api/http2_macros.h"
namespace http2 {
std::ostream& operator<<(std::ostream& out,
HeadersPayloadDecoder::PayloadState v) {
switch (v) {
case HeadersPayloadDecoder::PayloadState::kReadPadLength:
return out << "kReadPadLength";
case HeadersPayloadDecoder::PayloadState::kStartDecodingPriorityFields:
return out << "kStartDecodingPriorityFields";
case HeadersPayloadDecoder::PayloadState::kResumeDecodingPriorityFields:
return out << "kResumeDecodingPriorityFields";
case HeadersPayloadDecoder::PayloadState::kReadPayload:
return out << "kReadPayload";
case HeadersPayloadDecoder::PayloadState::kSkipPadding:
return out << "kSkipPadding";
}
// Since the value doesn't come over the wire, only a programming bug should
// result in reaching this point.
int unknown = static_cast<int>(v);
HTTP2_BUG << "Invalid HeadersPayloadDecoder::PayloadState: " << unknown;
return out << "HeadersPayloadDecoder::PayloadState(" << unknown << ")";
}
DecodeStatus HeadersPayloadDecoder::StartDecodingPayload(
FrameDecoderState* state,
DecodeBuffer* db) {
const Http2FrameHeader& frame_header = state->frame_header();
const uint32_t total_length = frame_header.payload_length;
DVLOG(2) << "HeadersPayloadDecoder::StartDecodingPayload: " << frame_header;
DCHECK_EQ(Http2FrameType::HEADERS, frame_header.type);
DCHECK_LE(db->Remaining(), total_length);
DCHECK_EQ(0, frame_header.flags &
~(Http2FrameFlag::END_STREAM | Http2FrameFlag::END_HEADERS |
Http2FrameFlag::PADDED | Http2FrameFlag::PRIORITY));
// Special case for HEADERS frames that contain only the HPACK block
// (fragment or whole) and that fit fully into the decode buffer.
// Why? Unencoded browser GET requests are typically under 1K and HPACK
// commonly shrinks request headers by 80%, so we can expect this to
// be common.
// TODO(jamessynge) Add counters here and to Spdy for determining how
// common this situation is. A possible approach is to create a
// Http2FrameDecoderListener that counts the callbacks and then forwards
// them on to another listener, which makes it easy to add and remove
// counting on a connection or even frame basis.
// PADDED and PRIORITY both extra steps to decode, but if neither flag is
// set then we can decode faster.
const auto payload_flags = Http2FrameFlag::PADDED | Http2FrameFlag::PRIORITY;
if (!frame_header.HasAnyFlags(payload_flags)) {
DVLOG(2) << "StartDecodingPayload !IsPadded && !HasPriority";
if (db->Remaining() == total_length) {
DVLOG(2) << "StartDecodingPayload all present";
// Note that we don't cache the listener field so that the callee can
// replace it if the frame is bad.
// If this case is common enough, consider combining the 3 callbacks
// into one, especially if END_HEADERS is also set.
state->listener()->OnHeadersStart(frame_header);
if (total_length > 0) {
state->listener()->OnHpackFragment(db->cursor(), total_length);
db->AdvanceCursor(total_length);
}
state->listener()->OnHeadersEnd();
return DecodeStatus::kDecodeDone;
}
payload_state_ = PayloadState::kReadPayload;
} else if (frame_header.IsPadded()) {
payload_state_ = PayloadState::kReadPadLength;
} else {
DCHECK(frame_header.HasPriority()) << frame_header;
payload_state_ = PayloadState::kStartDecodingPriorityFields;
}
state->InitializeRemainders();
state->listener()->OnHeadersStart(frame_header);
return ResumeDecodingPayload(state, db);
}
DecodeStatus HeadersPayloadDecoder::ResumeDecodingPayload(
FrameDecoderState* state,
DecodeBuffer* db) {
DVLOG(2) << "HeadersPayloadDecoder::ResumeDecodingPayload "
<< "remaining_payload=" << state->remaining_payload()
<< "; db->Remaining=" << db->Remaining();
const Http2FrameHeader& frame_header = state->frame_header();
DCHECK_EQ(Http2FrameType::HEADERS, frame_header.type);
DCHECK_LE(state->remaining_payload_and_padding(),
frame_header.payload_length);
DCHECK_LE(db->Remaining(), state->remaining_payload_and_padding());
DecodeStatus status;
size_t avail;
while (true) {
DVLOG(2) << "HeadersPayloadDecoder::ResumeDecodingPayload payload_state_="
<< payload_state_;
switch (payload_state_) {
case PayloadState::kReadPadLength:
// ReadPadLength handles the OnPadLength callback, and updating the
// remaining_payload and remaining_padding fields. If the amount of
// padding is too large to fit in the frame's payload, ReadPadLength
// instead calls OnPaddingTooLong and returns kDecodeError.
status = state->ReadPadLength(db, /*report_pad_length*/ true);
if (status != DecodeStatus::kDecodeDone) {
return status;
}
if (!frame_header.HasPriority()) {
payload_state_ = PayloadState::kReadPayload;
continue;
}
HTTP2_FALLTHROUGH;
case PayloadState::kStartDecodingPriorityFields:
status = state->StartDecodingStructureInPayload(&priority_fields_, db);
if (status != DecodeStatus::kDecodeDone) {
payload_state_ = PayloadState::kResumeDecodingPriorityFields;
return status;
}
state->listener()->OnHeadersPriority(priority_fields_);
HTTP2_FALLTHROUGH;
case PayloadState::kReadPayload:
avail = state->AvailablePayload(db);
if (avail > 0) {
state->listener()->OnHpackFragment(db->cursor(), avail);
db->AdvanceCursor(avail);
state->ConsumePayload(avail);
}
if (state->remaining_payload() > 0) {
payload_state_ = PayloadState::kReadPayload;
return DecodeStatus::kDecodeInProgress;
}
HTTP2_FALLTHROUGH;
case PayloadState::kSkipPadding:
// SkipPadding handles the OnPadding callback.
if (state->SkipPadding(db)) {
state->listener()->OnHeadersEnd();
return DecodeStatus::kDecodeDone;
}
payload_state_ = PayloadState::kSkipPadding;
return DecodeStatus::kDecodeInProgress;
case PayloadState::kResumeDecodingPriorityFields:
status = state->ResumeDecodingStructureInPayload(&priority_fields_, db);
if (status != DecodeStatus::kDecodeDone) {
return status;
}
state->listener()->OnHeadersPriority(priority_fields_);
payload_state_ = PayloadState::kReadPayload;
continue;
}
HTTP2_BUG << "PayloadState: " << payload_state_;
}
}
} // namespace http2
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