Add Http2FrameDecoderAdapter.

net/spdy/http2_frame_decoder_adapter.cc

+// 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/spdy/http2_frame_decoder_adapter.h"
+
+// Logging policy: If an error in the input is detected, VLOG(n) is used so that
+// the option exists to debug the situation. Otherwise, this code mostly uses
+// DVLOG so that the logging does not slow down production code when things are
+// working OK.
+
+#include <stddef.h>
+
+#include <cstring>
+#include <string>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/optional.h"
+#include "base/strings/string_piece.h"
+#include "base/sys_byteorder.h"
+#include "net/http2/decoder/decode_buffer.h"
+#include "net/http2/decoder/decode_status.h"
+#include "net/http2/decoder/http2_frame_decoder.h"
+#include "net/http2/decoder/http2_frame_decoder_listener.h"
+#include "net/http2/http2_constants.h"
+#include "net/http2/http2_structures.h"
+#include "net/spdy/hpack/hpack_decoder_interface.h"
+#include "net/spdy/hpack/hpack_header_table.h"
+#include "net/spdy/spdy_alt_svc_wire_format.h"
+#include "net/spdy/spdy_bug_tracker.h"
+#include "net/spdy/spdy_frame_builder.h"
+#include "net/spdy/spdy_header_block.h"
+#include "net/spdy/spdy_headers_handler_interface.h"
+#include "net/spdy/spdy_protocol.h"
+
+using std::string;
+
+namespace net {
+
+namespace {
+
+const bool kHasPriorityFields = true;
+const bool kNotHasPriorityFields = false;
+
+const Http2FrameType kFrameTypeBlocked = Http2FrameType(11);
+
+bool IsPaddable(Http2FrameType type) {
+  return type == Http2FrameType::DATA || type == Http2FrameType::HEADERS ||
+         type == Http2FrameType::PUSH_PROMISE;
+}
+
+SpdyFrameType ToSpdyFrameType(Http2FrameType type) {
+  return SpdyConstants::ParseFrameType(static_cast<int>(type));
+}
+
+uint64_t ToSpdyPingId(const Http2PingFields& ping) {
+  uint64_t v;
+  std::memcpy(&v, ping.opaque_data, Http2PingFields::EncodedSize());
+  return base::NetToHost64(v);
+}
+
+// Overwrites the fields of the header with invalid values, for the purpose
+// of identifying reading of unset fields. Only takes effect for debug builds.
+// In Address Sanatizer builds, it also marks the fields as un-readable.
+void CorruptFrameHeader(Http2FrameHeader* header) {
+#ifndef NDEBUG
+  // Beyond a valid payload length, which is 2^24 - 1.
+  header->payload_length = 0x1010dead;
+  // An unsupported frame type.
+  header->type = Http2FrameType(0x80);
+  DCHECK(!IsSupportedHttp2FrameType(header->type));
+  // Frame flag bits that aren't used by any supported frame type.
+  header->flags = Http2FrameFlag(0xd2);
+  // A stream id with the reserved high-bit (R in the RFC) set.
+  // 2129510127 when the high-bit is cleared.
+  header->stream_id = 0xfeedbeef;
+#endif
+}
+
+class Http2DecoderAdapter : public SpdyFramerDecoderAdapter,
+                            public Http2FrameDecoderListener {
+  typedef SpdyFramer::SpdyState SpdyState;
+  typedef SpdyFramer::SpdyError SpdyError;
+
+ public:
+  explicit Http2DecoderAdapter(SpdyFramer* outer_framer)
+      : SpdyFramerDecoderAdapter(), outer_framer_(outer_framer) {
+    DVLOG(1) << "Http2DecoderAdapter ctor, outer_framer=" << outer_framer;
+    ResetInternal();
+  }
+  ~Http2DecoderAdapter() override {}
+
+  // ===========================================================================
+  // Implementations of the pure virtual methods from SpdyFramerDecoderAdapter;
+  // the other virtual methods of SpdyFramerDecoderAdapter have satsifactory
+  // default implementations.
+
+  // Passes the call on to the HPACK decoder.
+  void SetDecoderHeaderTableDebugVisitor(
+      std::unique_ptr<HpackHeaderTable::DebugVisitorInterface> visitor)
+      override {
+    GetHpackDecoder()->SetHeaderTableDebugVisitor(std::move(visitor));
+  }
+
+  size_t ProcessInput(const char* data, size_t len) override {
+    size_t limit = outer_framer_->recv_frame_size_limit();
+    frame_decoder_->set_maximum_payload_size(limit);
+
+    size_t total_processed = 0;
+    while (len > 0 && spdy_state_ != SpdyFramer::SPDY_ERROR) {
+      // Process one at a time so that we update the adapter's internal
+      // state appropriately.
+      const size_t processed = ProcessInputFrame(data, len);
+
+      // We had some data, and weren't in an error state, so should have
+      // processed/consumed at least one byte of it, even if we then ended up
+      // in an error state.
+      DCHECK(processed > 0) << "processed=" << processed
+                            << "   spdy_state_=" << spdy_state_
+                            << "   spdy_error_=" << spdy_error_;
+
+      data += processed;
+      len -= processed;
+      total_processed += processed;
+      if (process_single_input_frame() || processed == 0) {
+        break;
+      }
+    }
+    return total_processed;
+  }
+
+  void Reset() override { ResetInternal(); }
+
+  SpdyState state() const override { return spdy_state_; }
+
+  SpdyError error_code() const override { return spdy_error_; }
+
+  bool probable_http_response() const override {
+    return latched_probable_http_response_;
+  }
+
+  // ===========================================================================
+  // Implementations of the methods declared by Http2FrameDecoderListener.
+
+  // Called once the common frame header has been decoded for any frame.
+  // This function is largely based on SpdyFramer::ValidateFrameHeader
+  // and some parts of SpdyFramer::ProcessCommonHeader.
+  bool OnFrameHeader(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnFrameHeader: " << header;
+    decoded_frame_header_ = true;
+    if (!latched_probable_http_response_) {
+      latched_probable_http_response_ = header.IsProbableHttpResponse();
+    }
+    if (!IsSupportedHttp2FrameType(header.type) &&
+        header.type != kFrameTypeBlocked) {
+      // In HTTP2 we ignore unknown frame types for extensibility, as long as
+      // the rest of the control frame header is valid.
+      // We rely on the visitor to check validity of stream_id.
+      bool valid_stream = visitor()->OnUnknownFrame(
+          header.stream_id, static_cast<int>(header.type));
+      if (has_expected_frame_type_ && header.type != expected_frame_type_) {
+        // Report an unexpected frame error and close the connection if we
+        // expect a known frame type (probably CONTINUATION) and receive an
+        // unknown frame.
+        VLOG(1) << "The framer was expecting to receive a "
+                << expected_frame_type_
+                << " frame, but instead received an unknown frame of type "
+                << header.type;
+        SetSpdyErrorAndNotify(SpdyError::SPDY_UNEXPECTED_FRAME);
+        return false;
+      } else if (!valid_stream) {
+        // Report an invalid frame error if the stream_id is not valid.
+        VLOG(1) << "Unknown control frame type " << header.type
+                << " received on invalid stream " << header.stream_id;
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_CONTROL_FRAME);
+        return false;
+      } else {
+        DVLOG(1) << "Ignoring unknown frame type " << header.type;
+        return true;
+      }
+    }
+
+    SpdyFrameType frame_type = ToSpdyFrameType(header.type);
+    if (!SpdyConstants::IsValidHTTP2FrameStreamId(header.stream_id,
+                                                  frame_type)) {
+      VLOG(1) << "The framer received an invalid streamID of "
+              << header.stream_id << " for a frame of type " << header.type;
+      SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_STREAM_ID);
+      return false;
+    }
+
+    if (has_expected_frame_type_ && header.type != expected_frame_type_) {
+      VLOG(1) << "Expected frame type " << expected_frame_type_ << ", not "
+              << header.type;
+      SetSpdyErrorAndNotify(SpdyError::SPDY_UNEXPECTED_FRAME);
+      return false;
+    }
+
+    if (!has_expected_frame_type_ &&
+        header.type == Http2FrameType::CONTINUATION) {
+      VLOG(1) << "Got CONTINUATION frame when not expected.";
+      SetSpdyErrorAndNotify(SpdyError::SPDY_UNEXPECTED_FRAME);
+      return false;
+    }
+
+    if (header.type == Http2FrameType::DATA) {
+      // For some reason SpdyFramer still rejects invalid DATA frame flags.
+      uint8_t valid_flags =
+          Http2FrameFlag::FLAG_PADDED | Http2FrameFlag::FLAG_END_STREAM;
+      if (header.HasAnyFlags(~valid_flags)) {
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_DATA_FRAME_FLAGS);
+        return false;
+      }
+    }
+
+    return true;
+  }
+
+  void OnDataStart(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnDataStart: " << header;
+
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      frame_header_ = header;
+      has_frame_header_ = true;
+      visitor()->OnDataFrameHeader(header.stream_id, header.payload_length,
+                                   header.IsEndStream());
+    }
+  }
+
+  void OnDataPayload(const char* data, size_t len) override {
+    DVLOG(1) << "OnDataPayload: len=" << len;
+    DCHECK(has_frame_header_);
+    DCHECK_EQ(frame_header_.type, Http2FrameType::DATA);
+    visitor()->OnStreamFrameData(frame_header().stream_id, data, len);
+  }
+
+  void OnDataEnd() override {
+    DVLOG(1) << "OnDataEnd";
+    DCHECK(has_frame_header_);
+    DCHECK_EQ(frame_header_.type, Http2FrameType::DATA);
+    if (frame_header().IsEndStream()) {
+      visitor()->OnStreamEnd(frame_header().stream_id);
+    }
+    opt_pad_length_.reset();
+  }
+
+  void OnHeadersStart(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnHeadersStart: " << header;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      frame_header_ = header;
+      has_frame_header_ = true;
+      if (header.HasPriority()) {
+        // Once we've got the priority fields, then we can report the arrival
+        // of this HEADERS frame.
+        on_headers_called_ = false;
+        return;
+      }
+      on_headers_called_ = true;
+      ReportReceiveCompressedFrame(header);
+      visitor()->OnHeaders(header.stream_id, kNotHasPriorityFields,
+                           0,      // priority
+                           0,      // parent_stream_id
+                           false,  // exclusive
+                           header.IsEndStream(), header.IsEndHeaders());
+      CommonStartHpackBlock();
+    }
+  }
+
+  void OnHeadersPriority(const Http2PriorityFields& priority) override {
+    DVLOG(1) << "OnHeadersPriority: " << priority;
+    DCHECK(has_frame_header_);
+    DCHECK_EQ(frame_type(), Http2FrameType::HEADERS) << frame_header_;
+    DCHECK(frame_header_.HasPriority());
+    DCHECK(!on_headers_called_);
+    on_headers_called_ = true;
+    ReportReceiveCompressedFrame(frame_header_);
+    visitor()->OnHeaders(frame_header_.stream_id, kHasPriorityFields,
+                         priority.weight, priority.stream_dependency,
+                         priority.is_exclusive, frame_header_.IsEndStream(),
+                         frame_header_.IsEndHeaders());
+    CommonStartHpackBlock();
+  }
+
+  void OnHpackFragment(const char* data, size_t len) override {
+    DVLOG(1) << "OnHpackFragment: len=" << len;
+    on_hpack_fragment_called_ = true;
+    if (!GetHpackDecoder()->HandleControlFrameHeadersData(data, len)) {
+      SetSpdyErrorAndNotify(SpdyError::SPDY_DECOMPRESS_FAILURE);
+      return;
+    }
+  }
+
+  void OnHeadersEnd() override {
+    DVLOG(1) << "OnHeadersEnd";
+    CommonHpackFragmentEnd();
+    opt_pad_length_.reset();
+  }
+
+  void OnPriorityFrame(const Http2FrameHeader& header,
+                       const Http2PriorityFields& priority) override {
+    DVLOG(1) << "OnPriorityFrame: " << header << "; priority: " << priority;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      visitor()->OnPriority(header.stream_id, priority.stream_dependency,
+                            priority.weight, priority.is_exclusive);
+    }
+  }
+
+  void OnContinuationStart(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnContinuationStart: " << header;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      DCHECK(has_hpack_first_frame_header_);
+      if (header.stream_id != hpack_first_frame_header_.stream_id) {
+        SetSpdyErrorAndNotify(SpdyError::SPDY_UNEXPECTED_FRAME);
+        return;
+      }
+      frame_header_ = header;
+      has_frame_header_ = true;
+      ReportReceiveCompressedFrame(header);
+      visitor()->OnContinuation(header.stream_id, header.IsEndHeaders());
+    }
+  }
+
+  void OnContinuationEnd() override {
+    DVLOG(1) << "OnContinuationEnd";
+    CommonHpackFragmentEnd();
+  }
+
+  void OnPadLength(size_t trailing_length) override {
+    DVLOG(1) << "OnPadLength: " << trailing_length;
+    opt_pad_length_ = trailing_length;
+    if (frame_header_.type == Http2FrameType::DATA) {
+      visitor()->OnStreamPadding(stream_id(), 1);
+    } else if (frame_header_.type == Http2FrameType::HEADERS) {
+      CHECK_LT(trailing_length, 256u);
+    }
+  }
+
+  void OnPadding(const char* padding, size_t skipped_length) override {
+    DVLOG(1) << "OnPadding: " << skipped_length;
+    if (frame_header_.type == Http2FrameType::DATA) {
+      visitor()->OnStreamPadding(stream_id(), skipped_length);
+    } else {
+      MaybeAnnounceEmptyFirstHpackFragment();
+    }
+  }
+
+  void OnRstStream(const Http2FrameHeader& header,
+                   Http2ErrorCode error_code) override {
+    DVLOG(1) << "OnRstStream: " << header << "; code=" << error_code;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      // Treat unrecognized error codes as INTERNAL_ERROR as
+      // recommended by the HTTP/2 spec.
+      if (!IsSupportedHttp2ErrorCode(error_code)) {
+        error_code = Http2ErrorCode::INTERNAL_ERROR;
+      }
+      SpdyRstStreamStatus status = RST_STREAM_INTERNAL_ERROR;
+      uint32_t status_raw = static_cast<int>(error_code);
+      if (SpdyConstants::IsValidRstStreamStatus(status_raw)) {
+        status = SpdyConstants::ParseRstStreamStatus(status_raw);
+      }
+      visitor()->OnRstStream(header.stream_id, status);
+    }
+  }
+
+  void OnSettingsStart(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnSettingsStart: " << header;
+    if (IsOkToStartFrame(header) && HasRequiredStreamIdZero(header)) {
+      frame_header_ = header;
+      has_frame_header_ = true;
+      visitor()->OnSettings(0);
+    }
+  }
+
+  void OnSetting(const Http2SettingFields& setting_fields) override {
+    DVLOG(1) << "OnSetting: " << setting_fields;
+    SpdySettingsIds setting_id;
+    if (!SpdyConstants::ParseSettingsId(
+            static_cast<int>(setting_fields.parameter), &setting_id)) {
+      DVLOG(1) << "Ignoring invalid setting id: " << setting_fields;
+      return;
+    }
+    visitor()->OnSetting(setting_id, 0, setting_fields.value);
+  }
+
+  void OnSettingsEnd() override {
+    DVLOG(1) << "OnSettingsEnd";
+    visitor()->OnSettingsEnd();
+  }
+
+  void OnSettingsAck(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnSettingsAck: " << header;
+    if (IsOkToStartFrame(header) && HasRequiredStreamIdZero(header)) {
+      visitor()->OnSettingsAck();
+    }
+  }
+
+  void OnPushPromiseStart(const Http2FrameHeader& header,
+                          const Http2PushPromiseFields& promise,
+                          size_t total_padding_length) override {
+    DVLOG(1) << "OnPushPromiseStart: " << header << "; promise: " << promise
+             << "; total_padding_length: " << total_padding_length;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      if (promise.promised_stream_id == 0) {
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_CONTROL_FRAME);
+        return;
+      }
+      frame_header_ = header;
+      has_frame_header_ = true;
+      ReportReceiveCompressedFrame(header);
+      visitor()->OnPushPromise(header.stream_id, promise.promised_stream_id,
+                               header.IsEndHeaders());
+      CommonStartHpackBlock();
+    }
+  }
+
+  void OnPushPromiseEnd() override {
+    DVLOG(1) << "OnPushPromiseEnd";
+    CommonHpackFragmentEnd();
+    opt_pad_length_.reset();
+  }
+
+  void OnPing(const Http2FrameHeader& header,
+              const Http2PingFields& ping) override {
+    DVLOG(1) << "OnPing: " << header << "; ping: " << ping;
+    if (IsOkToStartFrame(header) && HasRequiredStreamIdZero(header)) {
+      visitor()->OnPing(ToSpdyPingId(ping), false);
+    }
+  }
+
+  void OnPingAck(const Http2FrameHeader& header,
+                 const Http2PingFields& ping) override {
+    DVLOG(1) << "OnPingAck: " << header << "; ping: " << ping;
+    if (IsOkToStartFrame(header) && HasRequiredStreamIdZero(header)) {
+      visitor()->OnPing(ToSpdyPingId(ping), true);
+    }
+  }
+
+  void OnGoAwayStart(const Http2FrameHeader& header,
+                     const Http2GoAwayFields& goaway) override {
+    DVLOG(1) << "OnGoAwayStart: " << header << "; goaway: " << goaway;
+    if (IsOkToStartFrame(header) && HasRequiredStreamIdZero(header)) {
+      frame_header_ = header;
+      has_frame_header_ = true;
+      uint32_t status_raw = static_cast<int>(goaway.error_code);
+      SpdyGoAwayStatus status;
+      if (SpdyConstants::IsValidGoAwayStatus(status_raw)) {
+        status = SpdyConstants::ParseGoAwayStatus(status_raw);
+      } else {
+        // Treat unrecognized status codes as INTERNAL_ERROR as
+        // recommended by the HTTP/2 spec.
+        status = SpdyGoAwayStatus::GOAWAY_INTERNAL_ERROR;
+      }
+      visitor()->OnGoAway(goaway.last_stream_id, status);
+    }
+  }
+
+  void OnGoAwayOpaqueData(const char* data, size_t len) override {
+    DVLOG(1) << "OnGoAwayOpaqueData: len=" << len;
+    visitor()->OnGoAwayFrameData(data, len);
+  }
+
+  void OnGoAwayEnd() override {
+    DVLOG(1) << "OnGoAwayEnd";
+    visitor()->OnGoAwayFrameData(nullptr, 0);
+  }
+
+  void OnWindowUpdate(const Http2FrameHeader& header,
+                      uint32_t increment) override {
+    DVLOG(1) << "OnWindowUpdate: " << header << "; increment=" << increment;
+    if (IsOkToStartFrame(header)) {
+      visitor()->OnWindowUpdate(header.stream_id, increment);
+    }
+  }
+
+  void OnAltSvcStart(const Http2FrameHeader& header,
+                     size_t origin_length,
+                     size_t value_length) override {
+    DVLOG(1) << "OnAltSvcStart: " << header
+             << "; origin_length: " << origin_length
+             << "; value_length: " << value_length;
+    if (IsOkToStartFrame(header) && HasRequiredStreamId(header)) {
+      frame_header_ = header;
+      has_frame_header_ = true;
+      alt_svc_origin_.clear();
+      alt_svc_value_.clear();
+    }
+  }
+
+  void OnAltSvcOriginData(const char* data, size_t len) override {
+    DVLOG(1) << "OnAltSvcOriginData: len=" << len;
+    alt_svc_origin_.append(data, len);
+  }
+
+  // Called when decoding the Alt-Svc-Field-Value of an ALTSVC;
+  // the field is uninterpreted.
+  void OnAltSvcValueData(const char* data, size_t len) override {
+    DVLOG(1) << "OnAltSvcValueData: len=" << len;
+    alt_svc_value_.append(data, len);
+  }
+
+  void OnAltSvcEnd() override {
+    DVLOG(1) << "OnAltSvcEnd: origin.size(): " << alt_svc_origin_.size()
+             << "; value.size(): " << alt_svc_value_.size();
+    SpdyAltSvcWireFormat::AlternativeServiceVector altsvc_vector;
+    if (!SpdyAltSvcWireFormat::ParseHeaderFieldValue(alt_svc_value_,
+                                                     &altsvc_vector)) {
+      DLOG(ERROR) << "SpdyAltSvcWireFormat::ParseHeaderFieldValue failed.";
+      SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_CONTROL_FRAME);
+      return;
+    }
+    visitor()->OnAltSvc(frame_header_.stream_id, alt_svc_origin_,
+                        altsvc_vector);
+    // We assume that ALTSVC frames are rare, so get rid of the storage.
+    alt_svc_origin_.clear();
+    alt_svc_origin_.shrink_to_fit();
+    alt_svc_value_.clear();
+    alt_svc_value_.shrink_to_fit();
+  }
+
+  // Except for BLOCKED frames, all other unknown frames are
+  // effectively dropped.
+  void OnUnknownStart(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnUnknownStart: " << header;
+    if (IsOkToStartFrame(header)) {
+      if (header.type == kFrameTypeBlocked) {
+        visitor()->OnBlocked(header.stream_id);
+      }
+    }
+  }
+
+  void OnUnknownPayload(const char* data, size_t len) override {
+    DVLOG(1) << "OnUnknownPayload: len=" << len;
+  }
+
+  void OnUnknownEnd() override { DVLOG(1) << "OnUnknownEnd"; }
+
+  void OnPaddingTooLong(const Http2FrameHeader& header,
+                        size_t missing_length) override {
+    DVLOG(1) << "OnPaddingTooLong: " << header
+             << "; missing_length: " << missing_length;
+    if (header.type == Http2FrameType::DATA) {
+      if (header.payload_length == 0) {
+        DCHECK_EQ(1u, missing_length);
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_DATA_FRAME_FLAGS);
+        return;
+      }
+      visitor()->OnStreamPadding(header.stream_id, 1);
+    }
+    SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_PADDING);
+  }
+
+  void OnFrameSizeError(const Http2FrameHeader& header) override {
+    DVLOG(1) << "OnFrameSizeError: " << header;
+    size_t recv_limit = outer_framer_->recv_frame_size_limit();
+    if (header.payload_length > recv_limit) {
+      SetSpdyErrorAndNotify(SpdyError::SPDY_OVERSIZED_PAYLOAD);
+      return;
+    }
+    if (header.type != Http2FrameType::DATA &&
+        header.payload_length > recv_limit) {
+      SetSpdyErrorAndNotify(SpdyError::SPDY_CONTROL_PAYLOAD_TOO_LARGE);
+      return;
+    }
+    switch (header.type) {
+      case Http2FrameType::GOAWAY:
+      case Http2FrameType::ALTSVC:
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_CONTROL_FRAME);
+        break;
+      default:
+        SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_CONTROL_FRAME_SIZE);
+    }
+  }
+
+ private:
+  // Decodes the input up to the next frame boundary (i.e. at most one frame),
+  // stopping early if an error is detected.
+  size_t ProcessInputFrame(const char* data, size_t len) {
+    DCHECK_NE(spdy_state_, SpdyState::SPDY_ERROR);
+    DecodeBuffer db(data, len);
+    DecodeStatus status = frame_decoder_->DecodeFrame(&db);
+    if (spdy_state_ != SpdyFramer::SPDY_ERROR) {
+      DetermineSpdyState(status);
+    } else {
+      VLOG(1) << "ProcessInputFrame spdy_error_="
+              << SpdyFramer::ErrorCodeToString(spdy_error_);
+      if (spdy_error_ == SpdyError::SPDY_INVALID_PADDING && has_frame_header_ &&
+          frame_type() != Http2FrameType::DATA) {
+        // spdy_framer_test checks that all of the available frame payload
+        // has been consumed, so do that.
+        size_t total = remaining_total_payload();
+        if (total <= frame_header().payload_length) {
+          size_t avail = db.MinLengthRemaining(total);
+          VLOG(1) << "Skipping past " << avail << " bytes, of " << total
+                  << " total remaining in the frame's payload.";
+          db.AdvanceCursor(avail);
+        } else {
+          SPDY_BUG << "Total remaining (" << total
+                   << ") should not be greater than the payload length; "
+                   << frame_header();
+        }
+      }
+    }
+    return db.Offset();
+  }
+
+  // After decoding, determine the next SpdyState. Only called if the current
+  // state is NOT SpdyState::SPDY_ERROR (i.e. if none of the callback methods
+  // detected an error condition), because otherwise we assume that the callback
+  // method has set spdy_error_ appropriately.
+  void DetermineSpdyState(DecodeStatus status) {
+    DCHECK_EQ(spdy_error_, SpdyFramer::SPDY_NO_ERROR);
+    DCHECK(!HasError()) << spdy_error_;
+    switch (status) {
+      case DecodeStatus::kDecodeDone:
+        DVLOG(1) << "ProcessInputFrame -> DecodeStatus::kDecodeDone";
+        ResetBetweenFrames();
+        break;
+      case DecodeStatus::kDecodeInProgress:
+        DVLOG(1) << "ProcessInputFrame -> DecodeStatus::kDecodeInProgress";
+        if (decoded_frame_header_) {
+          if (IsDiscardingPayload()) {
+            set_spdy_state(SpdyState::SPDY_IGNORE_REMAINING_PAYLOAD);
+          } else if (has_frame_header_ &&
+                     frame_type() == Http2FrameType::DATA) {
+            if (IsReadingPaddingLength()) {
+              set_spdy_state(SpdyState::SPDY_READ_DATA_FRAME_PADDING_LENGTH);
+            } else if (IsSkippingPadding()) {
+              set_spdy_state(SpdyState::SPDY_CONSUME_PADDING);
+            } else {
+              set_spdy_state(SpdyState::SPDY_FORWARD_STREAM_FRAME);
+            }
+          } else {
+            set_spdy_state(SpdyState::SPDY_CONTROL_FRAME_PAYLOAD);
+          }
+        } else {
+          set_spdy_state(SpdyState::SPDY_READING_COMMON_HEADER);
+        }
+        break;
+      case DecodeStatus::kDecodeError:
+        VLOG(1) << "ProcessInputFrame -> DecodeStatus::kDecodeError";
+        if (IsDiscardingPayload()) {
+          if (remaining_total_payload() == 0) {
+            // Push the Http2FrameDecoder out of state kDiscardPayload now
+            // since doing so requires no input.
+            DecodeBuffer tmp("", 0);
+            DecodeStatus status = frame_decoder_->DecodeFrame(&tmp);
+            if (status != DecodeStatus::kDecodeDone) {
+              SPDY_BUG << "Expected to be done decoding the frame, not "
+                       << status;
+              SetSpdyErrorAndNotify(SpdyFramer::SPDY_INTERNAL_FRAMER_ERROR);
+            } else if (spdy_error_ != SpdyFramer::SPDY_NO_ERROR) {
+              SPDY_BUG << "Expected to have no error, not "
+                       << SpdyFramer::ErrorCodeToString(spdy_error_);
+            } else {
+              ResetBetweenFrames();
+            }
+          } else {
+            set_spdy_state(SpdyState::SPDY_IGNORE_REMAINING_PAYLOAD);
+          }
+        } else {
+          SetSpdyErrorAndNotify(SpdyFramer::SPDY_INVALID_CONTROL_FRAME);
+        }
+        break;
+    }
+  }
+
+  void ResetBetweenFrames() {
+    CorruptFrameHeader(&frame_header_);
+    decoded_frame_header_ = false;
+    has_frame_header_ = false;
+    set_spdy_state(SpdyState::SPDY_READY_FOR_FRAME);
+  }
+
+  // ResetInternal is called from the constructor, and during tests, but not
+  // otherwise (i.e. not between every frame).
+  void ResetInternal() {
+    set_spdy_state(SpdyState::SPDY_READY_FOR_FRAME);
+    spdy_error_ = SpdyError::SPDY_NO_ERROR;
+
+    decoded_frame_header_ = false;
+    has_frame_header_ = false;
+    on_headers_called_ = false;
+    on_hpack_fragment_called_ = false;
+    latched_probable_http_response_ = false;
+    has_expected_frame_type_ = false;
+
+    CorruptFrameHeader(&frame_header_);
+    CorruptFrameHeader(&hpack_first_frame_header_);
+
+    frame_decoder_.reset(new Http2FrameDecoder(this));
+  }
+
+  void set_spdy_state(SpdyState v) {
+    DVLOG(2) << "set_spdy_state(" << SpdyFramer::StateToString(v) << ")";
+    spdy_state_ = v;
+  }
+
+  void SetSpdyErrorAndNotify(SpdyError error) {
+    if (HasError()) {
+      DCHECK_EQ(spdy_state_, SpdyState::SPDY_ERROR);
+    } else {
+      VLOG(2) << "SetSpdyErrorAndNotify("
+              << SpdyFramer::ErrorCodeToString(error) << ")";
+      DCHECK_NE(error, SpdyError::SPDY_NO_ERROR);
+      spdy_error_ = error;
+      set_spdy_state(SpdyState::SPDY_ERROR);
+      frame_decoder_->set_listener(&no_op_listener_);
+      visitor()->OnError(outer_framer_);
+    }
+  }
+
+  bool HasError() const {
+    if (spdy_state_ == SpdyState::SPDY_ERROR) {
+      DCHECK_NE(error_code(), SpdyError::SPDY_NO_ERROR);
+      return true;
+    } else {
+      DCHECK_EQ(error_code(), SpdyError::SPDY_NO_ERROR);
+      return false;
+    }
+  }
+
+  const Http2FrameHeader& frame_header() const {
+    DCHECK(has_frame_header_);
+    return frame_header_;
+  }
+
+  uint32_t stream_id() const { return frame_header().stream_id; }
+
+  Http2FrameType frame_type() const { return frame_header().type; }
+
+  size_t remaining_total_payload() const {
+    DCHECK(has_frame_header_);
+    size_t remaining = frame_decoder_->remaining_payload();
+    if (IsPaddable(frame_type()) && frame_header_.IsPadded()) {
+      remaining += frame_decoder_->remaining_padding();
+    }
+    return remaining;
+  }
+
+  bool IsReadingPaddingLength() {
+    bool result = frame_header_.IsPadded() && !opt_pad_length_;
+    DVLOG(2) << "Http2DecoderAdapter::IsReadingPaddingLength: " << result;
+    return result;
+  }
+  bool IsSkippingPadding() {
+    bool result = frame_header_.IsPadded() && opt_pad_length_ &&
+                  frame_decoder_->remaining_payload() == 0 &&
+                  frame_decoder_->remaining_padding() > 0;
+    DVLOG(2) << "Http2DecoderAdapter::IsSkippingPadding: " << result;
+    return result;
+  }
+  bool IsDiscardingPayload() {
+    bool result =
+        decoded_frame_header_ && frame_decoder_->IsDiscardingPayload();
+    DVLOG(2) << "Http2DecoderAdapter::IsDiscardingPayload: " << result;
+    return result;
+  }
+  // Called from OnXyz or OnXyzStart methods to decide whether it is OK to
+  // handle the callback.
+  bool IsOkToStartFrame(const Http2FrameHeader& header) {
+    DVLOG(3) << "IsOkToStartFrame";
+    if (HasError()) {
+      VLOG(2) << "HasError()";
+      return false;
+    }
+    DCHECK(!has_frame_header_);
+    if (has_expected_frame_type_ && header.type != expected_frame_type_) {
+      VLOG(1) << "Expected frame type " << expected_frame_type_ << ", not "
+              << header.type;
+      SetSpdyErrorAndNotify(SpdyError::SPDY_UNEXPECTED_FRAME);
+      return false;
+    }
+
+    return true;
+  }
+
+  bool HasRequiredStreamId(uint32_t stream_id) {
+    DVLOG(3) << "HasRequiredStreamId: " << stream_id;
+    if (HasError()) {
+      VLOG(2) << "HasError()";
+      return false;
+    }
+    if (stream_id != 0) {
+      return true;
+    }
+    VLOG(1) << "Stream Id is required, but zero provided";
+    SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_STREAM_ID);
+    return false;
+  }
+
+  bool HasRequiredStreamId(const Http2FrameHeader& header) {
+    return HasRequiredStreamId(header.stream_id);
+  }
+
+  bool HasRequiredStreamIdZero(uint32_t stream_id) {
+    DVLOG(3) << "HasRequiredStreamIdZero: " << stream_id;
+    if (HasError()) {
+      VLOG(2) << "HasError()";
+      return false;
+    }
+    if (stream_id == 0) {
+      return true;
+    }
+    VLOG(1) << "Stream Id was not zero, as required: " << stream_id;
+    SetSpdyErrorAndNotify(SpdyError::SPDY_INVALID_STREAM_ID);
+    return false;
+  }
+
+  bool HasRequiredStreamIdZero(const Http2FrameHeader& header) {
+    return HasRequiredStreamIdZero(header.stream_id);
+  }
+
+  void ReportReceiveCompressedFrame(const Http2FrameHeader& header) {
+    if (debug_visitor() != nullptr) {
+      size_t total = header.payload_length + Http2FrameHeader::EncodedSize();
+      debug_visitor()->OnReceiveCompressedFrame(
+          header.stream_id, ToSpdyFrameType(header.type), total);
+    }
+  }
+
+  HpackDecoderInterface* GetHpackDecoder() {
+    if (hpack_decoder_ == nullptr) {
+      hpack_decoder_ = outer_framer_->GetHpackDecoderForAdapter();
+    }
+    return hpack_decoder_;
+  }
+
+  void CommonStartHpackBlock() {
+    DVLOG(1) << "CommonStartHpackBlock";
+    DCHECK(!has_hpack_first_frame_header_);
+    if (!frame_header_.IsEndHeaders()) {
+      hpack_first_frame_header_ = frame_header_;
+      has_hpack_first_frame_header_ = true;
+    } else {
+      CorruptFrameHeader(&hpack_first_frame_header_);
+    }
+    on_hpack_fragment_called_ = false;
+    SpdyHeadersHandlerInterface* handler =
+        visitor()->OnHeaderFrameStart(stream_id());
+    if (handler == nullptr) {
+      SPDY_BUG << "visitor_->OnHeaderFrameStart returned nullptr";
+      SetSpdyErrorAndNotify(SpdyError::SPDY_INTERNAL_FRAMER_ERROR);
+      return;
+    }
+    GetHpackDecoder()->HandleControlFrameHeadersStart(handler);
+  }
+
+  // SpdyFramer calls HandleControlFrameHeadersData even if there are zero
+  // fragment bytes in the first frame, so do the same.
+  void MaybeAnnounceEmptyFirstHpackFragment() {
+    if (!on_hpack_fragment_called_) {
+      OnHpackFragment(nullptr, 0);
+      DCHECK(on_hpack_fragment_called_);
+    }
+  }
+
+  void CommonHpackFragmentEnd() {
+    DVLOG(1) << "CommonHpackFragmentEnd: stream_id=" << stream_id();
+    if (HasError()) {
+      VLOG(1) << "HasError(), returning";
+      return;
+    }
+    DCHECK(has_frame_header_);
+    MaybeAnnounceEmptyFirstHpackFragment();
+    if (frame_header_.IsEndHeaders()) {
+      DCHECK_EQ(has_hpack_first_frame_header_,
+                frame_type() == Http2FrameType::CONTINUATION)
+          << frame_header();
+      has_expected_frame_type_ = false;
+      if (GetHpackDecoder()->HandleControlFrameHeadersComplete(nullptr)) {
+        visitor()->OnHeaderFrameEnd(stream_id(), true);
+      } else {
+        SetSpdyErrorAndNotify(SpdyError::SPDY_DECOMPRESS_FAILURE);
+        return;
+      }
+      const Http2FrameHeader& first =
+          frame_type() == Http2FrameType::CONTINUATION
+              ? hpack_first_frame_header_
+              : frame_header_;
+      if (first.type == Http2FrameType::HEADERS && first.IsEndStream()) {
+        visitor()->OnStreamEnd(first.stream_id);
+      }
+      hpack_decoder_ = nullptr;
+      has_hpack_first_frame_header_ = false;
+      CorruptFrameHeader(&hpack_first_frame_header_);
+    } else {
+      DCHECK(has_hpack_first_frame_header_);
+      has_expected_frame_type_ = true;
+      expected_frame_type_ = Http2FrameType::CONTINUATION;
+    }
+  }
+
+  // The SpdyFramer that created this Http2FrameDecoderAdapter.
+  SpdyFramer* const outer_framer_;
+
+  // The HPACK decoder that we're using for the HPACK block that is currently
+  // being decoded. Cleared at the end of the block. Owned by the SpdyFramer.
+  HpackDecoderInterface* hpack_decoder_ = nullptr;
+
+  // The HTTP/2 frame decoder. Accessed via a unique_ptr to allow replacement
+  // (e.g. in tests) when Reset() is called.
+  std::unique_ptr<Http2FrameDecoder> frame_decoder_;
+
+  // The most recently decoded frame header; invalid after we reached the end
+  // of that frame.
+  Http2FrameHeader frame_header_;
+
+  // If decoding an HPACK block that is split across multiple frames, this holds
+  // the frame header of the HEADERS or PUSH_PROMISE that started the block.
+  Http2FrameHeader hpack_first_frame_header_;
+
+  // Amount of trailing padding. Currently used just as an indicator of whether
+  // OnPadLength has been called.
+  base::Optional<size_t> opt_pad_length_;
+
+  // Temporary buffers for the AltSvc fields.
+  string alt_svc_origin_;
+  string alt_svc_value_;
+
+  // Listener used if we transition to an error state; the listener ignores all
+  // the callbacks.
+  Http2FrameDecoderNoOpListener no_op_listener_;
+
+  // Next frame type expected. Currently only used for CONTINUATION frames,
+  // but could be used for detecting whether the first frame is a SETTINGS
+  // frame.
+  // TODO(jamessyng): Provide means to indicate that decoder should require
+  // SETTINGS frame as the first frame.
+  Http2FrameType expected_frame_type_;
+
+  // Attempt to duplicate the SpdyState and SpdyError values that SpdyFramer
+  // sets. Values determined by getting tests to pass.
+  SpdyState spdy_state_;
+  SpdyError spdy_error_;
+
+  // Has OnFrameHeader been called?
+  bool decoded_frame_header_ = false;
+
+  // Have we recorded an Http2FrameHeader for the current frame?
+  // We only do so if the decoder will make multiple callbacks for
+  // the frame; for example, for PING frames we don't make record
+  // the frame header, but for ALTSVC we do.
+  bool has_frame_header_ = false;
+
+  // Have we recorded an Http2FrameHeader for the current HPACK block?
+  // True only for multi-frame HPACK blocks.
+  bool has_hpack_first_frame_header_ = false;
+
+  // Has OnHeaders() already been called for current HEADERS block? Only
+  // meaningful between OnHeadersStart and OnHeadersPriority.
+  bool on_headers_called_;
+
+  // Has OnHpackFragment() already been called for current HPACK block?
+  // SpdyFramer will pass an empty buffer to the HPACK decoder if a HEADERS
+  // or PUSH_PROMISE has no HPACK data in it (e.g. a HEADERS frame with only
+  // padding). Detect that condition and replicate the behavior using this
+  // field.
+  bool on_hpack_fragment_called_;
+
+  // Have we seen a frame header that appears to be an HTTP/1 response?
+  bool latched_probable_http_response_ = false;
+
+  // Is expected_frame_type_ set?
+  bool has_expected_frame_type_ = false;
+};
+
+}  // namespace
+
+std::unique_ptr<SpdyFramerDecoderAdapter> CreateHttp2FrameDecoderAdapter(
+    SpdyFramer* outer_framer) {
+  return std::unique_ptr<SpdyFramerDecoderAdapter>(
+      new Http2DecoderAdapter(outer_framer));
+}
+
+}  // namespace net