Revert of Add new HTTP/2 and HPACK decoder in net/http2/.

net/http2/decoder/frame_decoder_state.h

-// 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.
-
-#ifndef NET_HTTP2_DECODER_FRAME_DECODER_STATE_H_
-#define NET_HTTP2_DECODER_FRAME_DECODER_STATE_H_
-
-// FrameDecoderState provides state and behaviors in support of decoding
-// the common frame header and the payload of all frame types.
-// It is an input to all of the payload decoders.
-
-// TODO(jamessynge): Since FrameDecoderState has far more than state in it,
-// rename to FrameDecoderHelper, or similar.
-
-#include <stddef.h>
-
-#include "base/logging.h"
-#include "net/base/net_export.h"
-#include "net/http2/decoder/decode_buffer.h"
-#include "net/http2/decoder/decode_status.h"
-#include "net/http2/decoder/http2_frame_decoder_listener.h"
-#include "net/http2/decoder/http2_structure_decoder.h"
-#include "net/http2/http2_constants.h"
-#include "net/http2/http2_structures.h"
-
-namespace net {
-namespace test {
-class FrameDecoderStatePeer;
-}  // namespace test
-
-class NET_EXPORT_PRIVATE FrameDecoderState {
- public:
-  FrameDecoderState() {}
-
-  // Sets the listener which the decoders should call as they decode HTTP/2
-  // frames. The listener can be changed at any time, which allows for replacing
-  // it with a no-op listener when an error is detected, either by the payload
-  // decoder (OnPaddingTooLong or OnFrameSizeError) or by the "real" listener.
-  // That in turn allows us to define Http2FrameDecoderListener such that all
-  // methods have return type void, with no direct way to indicate whether the
-  // decoder should stop, and to eliminate from the decoder all checks of the
-  // return value. Instead the listener/caller can simply replace the current
-  // listener with a no-op listener implementation.
-  // TODO(jamessynge): Make set_listener private as only Http2FrameDecoder
-  // and tests need to set it, so it doesn't need to be public.
-  void set_listener(Http2FrameDecoderListener* listener) {
-    listener_ = listener;
-  }
-  Http2FrameDecoderListener* listener() const { return listener_; }
-
-  // The most recently decoded frame header.
-  const Http2FrameHeader& frame_header() const { return frame_header_; }
-
-  // Decode a structure in the payload, adjusting remaining_payload_ to account
-  // for the consumed portion of the payload. Returns kDecodeDone when fully
-  // decoded, kDecodeError if it ran out of payload before decoding completed,
-  // and kDecodeInProgress if the decode buffer didn't have enough of the
-  // remaining payload.
-  template <class S>
-  DecodeStatus StartDecodingStructureInPayload(S* out, DecodeBuffer* db) {
-    DVLOG(2) << __func__ << "\n\tdb->Remaining=" << db->Remaining()
-             << "\n\tremaining_payload_=" << remaining_payload_
-             << "\n\tneed=" << S::EncodedSize();
-    DecodeStatus status =
-        structure_decoder_.Start(out, db, &remaining_payload_);
-    if (status != DecodeStatus::kDecodeError) {
-      return status;
-    }
-    DVLOG(2) << "StartDecodingStructureInPayload: detected frame size error";
-    return ReportFrameSizeError();
-  }
-
-  // Resume decoding of a structure that has been split across buffers,
-  // adjusting remaining_payload_ to account for the consumed portion of
-  // the payload. Returns values are as for StartDecodingStructureInPayload.
-  template <class S>
-  DecodeStatus ResumeDecodingStructureInPayload(S* out, DecodeBuffer* db) {
-    DVLOG(2) << __func__ << "\n\tdb->Remaining=" << db->Remaining()
-             << "\n\tremaining_payload_=" << remaining_payload_;
-    if (structure_decoder_.Resume(out, db, &remaining_payload_)) {
-      return DecodeStatus::kDecodeDone;
-    } else if (remaining_payload_ > 0) {
-      return DecodeStatus::kDecodeInProgress;
-    } else {
-      DVLOG(2) << "ResumeDecodingStructureInPayload: detected frame size error";
-      return ReportFrameSizeError();
-    }
-  }
-
-  // Initializes the two remaining* fields, which is needed if the frame's
-  // payload is split across buffers, or the decoder calls ReadPadLength or
-  // StartDecodingStructureInPayload, and of course the methods below which
-  // read those fields, as their names imply.
-  void InitializeRemainders() {
-    remaining_payload_ = frame_header().payload_length;
-    // Note that remaining_total_payload() relies on remaining_padding_ being
-    // zero for frames that have no padding.
-    remaining_padding_ = 0;
-  }
-
-  // Returns the number of bytes of the frame's payload that remain to be
-  // decoded, including any trailing padding. This method must only be called
-  // after the variables have been initialized, which in practice means once a
-  // payload decoder has called InitializeRemainders and/or ReadPadLength.
-  size_t remaining_total_payload() const {
-    DCHECK(IsPaddable() || remaining_padding_ == 0) << frame_header();
-    return remaining_payload_ + remaining_padding_;
-  }
-
-  // Returns the number of bytes of the frame's payload that remain to be
-  // decoded, excluding any trailing padding. This method must only be called
-  // after the variable has been initialized, which in practice means once a
-  // payload decoder has called InitializeRemainders; ReadPadLength will deduct
-  // the total number of padding bytes from remaining_payload_, including the
-  // size of the Pad Length field itself (1 byte).
-  size_t remaining_payload() const { return remaining_payload_; }
-
-  // Returns the number of bytes of the frame's payload that remain to be
-  // decoded, including any trailing padding. This method must only be called if
-  // the frame type allows padding, and after the variable has been initialized,
-  // which in practice means once a payload decoder has called
-  // InitializeRemainders and/or ReadPadLength.
-  size_t remaining_payload_and_padding() const {
-    DCHECK(IsPaddable()) << frame_header();
-    return remaining_payload_ + remaining_padding_;
-  }
-
-  // Returns the number of bytes of trailing padding after the payload that
-  // remain to be decoded. This method must only be called if the frame type
-  // allows padding, and after the variable has been initialized, which in
-  // practice means once a payload decoder has called InitializeRemainders,
-  // and isn't set to a non-zero value until ReadPadLength has been called.
-  uint32_t remaining_padding() const {
-    DCHECK(IsPaddable()) << frame_header();
-    return remaining_padding_;
-  }
-
-  // Returns the amount of trailing padding after the payload that remains to be
-  // decoded.
-  uint32_t remaining_padding_for_test() const { return remaining_padding_; }
-
-  // How many bytes of the remaining payload are in db?
-  size_t AvailablePayload(DecodeBuffer* db) const {
-    return db->MinLengthRemaining(remaining_payload_);
-  }
-
-  // How many bytes of the remaining payload and padding are in db?
-  // Call only for frames whose type is paddable.
-  size_t AvailablePayloadAndPadding(DecodeBuffer* db) const {
-    DCHECK(IsPaddable()) << frame_header();
-    return db->MinLengthRemaining(remaining_payload_ + remaining_padding_);
-  }
-
-  // How many bytes of the padding that have not yet been skipped are in db?
-  // Call only after remaining_padding_ has been set (for padded frames), or
-  // been cleared (for unpadded frames); and after all of the non-padding
-  // payload has been decoded.
-  size_t AvailablePadding(DecodeBuffer* db) const {
-    DCHECK(IsPaddable()) << frame_header();
-    DCHECK_EQ(remaining_payload_, 0u);
-    return db->MinLengthRemaining(remaining_padding_);
-  }
-
-  // Reduces remaining_payload_ by amount. To be called by a payload decoder
-  // after it has passed a variable length portion of the payload to the
-  // listener; remaining_payload_ will be automatically reduced when fixed
-  // size structures and padding, including the Pad Length field, are decoded.
-  void ConsumePayload(size_t amount) {
-    DCHECK_LE(amount, remaining_payload_);
-    remaining_payload_ -= amount;
-  }
-
-  // Reads the Pad Length field into remaining_padding_, and appropriately sets
-  // remaining_payload_. When present, the Pad Length field is always the first
-  // field in the payload, which this method relies on so that the caller need
-  // not set remaining_payload_ before calling this method.
-  // If report_pad_length is true, calls the listener's OnPadLength method when
-  // it decodes the Pad Length field.
-  // Returns kDecodeDone if the decode buffer was not empty (i.e. because the
-  // field is only a single byte long, it can always be decoded if the buffer is
-  // not empty).
-  // Returns kDecodeError if the buffer is empty because the frame has no
-  // payload (i.e. payload_length() == 0).
-  // Returns kDecodeInProgress if the buffer is empty but the frame has a
-  // payload.
-  DecodeStatus ReadPadLength(DecodeBuffer* db, bool report_pad_length);
-
-  // Skip the trailing padding bytes; only call once remaining_payload_==0.
-  // Returns true when the padding has been skipped.
-  // Does NOT check that the padding is all zeroes.
-  bool SkipPadding(DecodeBuffer* db);
-
-  // Calls the listener's OnFrameSizeError method and returns kDecodeError.
-  DecodeStatus ReportFrameSizeError();
-
- private:
-  friend class Http2FrameDecoder;
-  friend class test::FrameDecoderStatePeer;
-
-  // Starts the decoding of a common frame header. Returns true if completed the
-  // decoding, false if the decode buffer didn't have enough data in it, in
-  // which case the decode buffer will have been drained and the caller should
-  // call ResumeDecodingFrameHeader when more data is available. This is called
-  // from Http2FrameDecoder, a friend class.
-  bool StartDecodingFrameHeader(DecodeBuffer* db) {
-    return structure_decoder_.Start(&frame_header_, db);
-  }
-
-  // Resumes decoding the common frame header after the preceding call to
-  // StartDecodingFrameHeader returned false, as did any subsequent calls to
-  // ResumeDecodingFrameHeader. This is called from Http2FrameDecoder,
-  // a friend class.
-  bool ResumeDecodingFrameHeader(DecodeBuffer* db) {
-    return structure_decoder_.Resume(&frame_header_, db);
-  }
-
-  // Clear any of the flags in the frame header that aren't set in valid_flags.
-  void RetainFlags(uint8_t valid_flags) {
-    frame_header_.RetainFlags(valid_flags);
-  }
-
-  // Clear all of the flags in the frame header; for use with frame types that
-  // don't define any flags, such as WINDOW_UPDATE.
-  void ClearFlags() { frame_header_.flags = Http2FrameFlag(); }
-
-  // Returns true if the type of frame being decoded can have padding.
-  bool IsPaddable() const {
-    return frame_header().type == Http2FrameType::DATA ||
-           frame_header().type == Http2FrameType::HEADERS ||
-           frame_header().type == Http2FrameType::PUSH_PROMISE;
-  }
-
-  Http2FrameDecoderListener* listener_ = nullptr;
-  Http2FrameHeader frame_header_;
-
-  // Number of bytes remaining to be decoded, if set; does not include the
-  // trailing padding once the length of padding has been determined.
-  // See ReadPadLength.
-  uint32_t remaining_payload_;
-
-  // The amount of trailing padding after the payload that remains to be
-  // decoded. See ReadPadLength.
-  uint32_t remaining_padding_;
-
-  // Generic decoder of structures, which takes care of buffering the needed
-  // bytes if the encoded structure is split across decode buffers.
-  Http2StructureDecoder structure_decoder_;
-};
-
-}  // namespace net
-
-#endif  // NET_HTTP2_DECODER_FRAME_DECODER_STATE_H_