net/quic/core/quic_headers_stream.cc

// Copyright 2013 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/quic/core/quic_headers_stream.h"

#include <algorithm>
#include <string>
#include <utility>

#include "base/macros.h"
#include "base/metrics/histogram_macros.h"
#include "base/strings/string_number_conversions.h"
#include "base/strings/stringprintf.h"
#include "net/quic/core/quic_bug_tracker.h"
#include "net/quic/core/quic_flags.h"
#include "net/quic/core/quic_header_list.h"
#include "net/quic/core/quic_server_session_base.h"
#include "net/quic/core/quic_spdy_session.h"
#include "net/quic/core/quic_time.h"
#include "net/spdy/spdy_protocol.h"

using base::StringPiece;
using net::HTTP2;
using net::SpdyFrameType;
using std::string;

namespace net {

namespace {

class HeaderTableDebugVisitor : public HpackHeaderTable::DebugVisitorInterface {
 public:
  HeaderTableDebugVisitor(
      const QuicClock* clock,
      std::unique_ptr<QuicHeadersStream::HpackDebugVisitor> visitor)
      : clock_(clock), headers_stream_hpack_visitor_(std::move(visitor)) {}

  int64_t OnNewEntry(const HpackEntry& entry) override {
    DVLOG(1) << entry.GetDebugString();
    return (clock_->ApproximateNow() - QuicTime::Zero()).ToMicroseconds();
  }

  void OnUseEntry(const HpackEntry& entry) override {
    const QuicTime::Delta elapsed(
        clock_->ApproximateNow() -
        QuicTime::Delta::FromMicroseconds(entry.time_added()) -
        QuicTime::Zero());
    DVLOG(1) << entry.GetDebugString() << " " << elapsed.ToMilliseconds()
             << " ms";
    headers_stream_hpack_visitor_->OnUseEntry(elapsed);
  }

 private:
  const QuicClock* clock_;
  std::unique_ptr<QuicHeadersStream::HpackDebugVisitor>
      headers_stream_hpack_visitor_;

  DISALLOW_COPY_AND_ASSIGN(HeaderTableDebugVisitor);
};

// When forced HOL blocking is enabled, extra bytes in the form of
// HTTP/2 DATA frame headers are inserted on the way down to the
// session layer.  |ForceAckListener| filters the |OnPacketAcked()|
// notifications generated by the session layer to not count the extra
// bytes.  Otherwise, code that is using ack listener on streams might
// consider it an error if more bytes are acked than were written to
// the stream, it is the case with some internal stats gathering code.
class ForceHolAckListener : public QuicAckListenerInterface {
 public:
  // |extra_bytes| should be initialized to the size of the HTTP/2
  // DATA frame header inserted when forced HOL blocking is enabled.
  ForceHolAckListener(QuicAckListenerInterface* stream_ack_listener,
                      int extra_bytes)
      : stream_ack_listener_(stream_ack_listener), extra_bytes_(extra_bytes) {
    DCHECK_GE(extra_bytes, 0);
  }

  void OnPacketAcked(int acked_bytes, QuicTime::Delta ack_delay_time) override {
    if (extra_bytes_ > 0) {
      // Don't count the added HTTP/2 DATA frame header bytes
      int delta = std::min(extra_bytes_, acked_bytes);
      extra_bytes_ -= delta;
      acked_bytes -= delta;
    }
    stream_ack_listener_->OnPacketAcked(acked_bytes, ack_delay_time);
  }

  void OnPacketRetransmitted(int retransmitted_bytes) override {
    stream_ack_listener_->OnPacketRetransmitted(retransmitted_bytes);
  }

 private:
  ~ForceHolAckListener() override {}

  scoped_refptr<QuicAckListenerInterface> stream_ack_listener_;
  int extra_bytes_;

  DISALLOW_COPY_AND_ASSIGN(ForceHolAckListener);
};

}  // namespace

QuicHeadersStream::HpackDebugVisitor::HpackDebugVisitor() {}

QuicHeadersStream::HpackDebugVisitor::~HpackDebugVisitor() {}

// A SpdyFramerVisitor that passes HEADERS frames to the QuicSpdyStream, and
// closes the connection if any unexpected frames are received.
class QuicHeadersStream::SpdyFramerVisitor
    : public SpdyFramerVisitorInterface,
      public SpdyFramerDebugVisitorInterface {
 public:
  explicit SpdyFramerVisitor(QuicHeadersStream* stream) : stream_(stream) {}

  void OnStreamFrameData(SpdyStreamId stream_id,
                         const char* data,
                         size_t len) override {
    if (stream_->OnStreamFrameData(stream_id, data, len)) {
      return;
    }
    CloseConnection("SPDY DATA frame received.");
  }

  void OnStreamEnd(SpdyStreamId stream_id) override {
    // The framer invokes OnStreamEnd after processing a frame that had the fin
    // bit set.
  }

  void OnStreamPadding(SpdyStreamId stream_id, size_t len) override {
    CloseConnection("SPDY frame padding received.");
  }

  SpdyHeadersHandlerInterface* OnHeaderFrameStart(
      SpdyStreamId /* stream_id */) override {
    return &header_list_;
  }

  void OnHeaderFrameEnd(SpdyStreamId /* stream_id */,
                        bool end_headers) override {
    if (end_headers) {
      if (stream_->IsConnected()) {
        stream_->OnHeaderList(header_list_);
      }
      header_list_.Clear();
    }
  }

  void OnError(SpdyFramer* framer) override {
    CloseConnection(base::StringPrintf(
        "SPDY framing error: %s",
        SpdyFramer::ErrorCodeToString(framer->error_code())));
  }

  void OnDataFrameHeader(SpdyStreamId stream_id,
                         size_t length,
                         bool fin) override {
    if (stream_->OnDataFrameHeader(stream_id, length, fin)) {
      return;
    }
    CloseConnection("SPDY DATA frame received.");
  }

  void OnRstStream(SpdyStreamId stream_id,
                   SpdyRstStreamStatus status) override {
    CloseConnection("SPDY RST_STREAM frame received.");
  }

  void OnSetting(SpdySettingsIds id, uint8_t flags, uint32_t value) override {
    if (!FLAGS_quic_respect_http2_settings_frame) {
      CloseConnection("SPDY SETTINGS frame received.");
      return;
    }
    switch (id) {
      case SETTINGS_HEADER_TABLE_SIZE:
        stream_->UpdateHeaderEncoderTableSize(value);
        break;
      case SETTINGS_ENABLE_PUSH:
        if (FLAGS_quic_enable_server_push_by_default &&
            stream_->session()->perspective() == Perspective::IS_SERVER) {
          // See rfc7540, Section 6.5.2.
          if (value > 1) {
            CloseConnection("Invalid value for SETTINGS_ENABLE_PUSH: " +
                            base::IntToString(value));
            return;
          }
          stream_->UpdateEnableServerPush(value > 0);
          break;
        } else {
          CloseConnection("Unsupported field of HTTP/2 SETTINGS frame: " +
                          base::IntToString(id));
        }
        break;
      // TODO(fayang): Need to support SETTINGS_MAX_HEADER_LIST_SIZE when
      // clients are actually sending it.
      default:
        CloseConnection("Unsupported field of HTTP/2 SETTINGS frame: " +
                        base::IntToString(id));
    }
  }

  void OnSettingsAck() override {
    if (!FLAGS_quic_respect_http2_settings_frame) {
      CloseConnection("SPDY SETTINGS frame received.");
    }
  }

  void OnSettingsEnd() override {
    if (!FLAGS_quic_respect_http2_settings_frame) {
      CloseConnection("SPDY SETTINGS frame received.");
    }
  }

  void OnPing(SpdyPingId unique_id, bool is_ack) override {
    CloseConnection("SPDY PING frame received.");
  }

  void OnGoAway(SpdyStreamId last_accepted_stream_id,
                SpdyGoAwayStatus status) override {
    CloseConnection("SPDY GOAWAY frame received.");
  }

  void OnHeaders(SpdyStreamId stream_id,
                 bool has_priority,
                 int weight,
                 SpdyStreamId parent_stream_id,
                 bool exclusive,
                 bool fin,
                 bool end) override {
    if (!stream_->IsConnected()) {
      return;
    }

    // TODO(mpw): avoid down-conversion and plumb SpdyStreamPrecedence through
    // QuicHeadersStream.
    SpdyPriority priority =
        has_priority ? Http2WeightToSpdy3Priority(weight) : 0;
    stream_->OnHeaders(stream_id, has_priority, priority, fin);
  }

  void OnWindowUpdate(SpdyStreamId stream_id, int delta_window_size) override {
    CloseConnection("SPDY WINDOW_UPDATE frame received.");
  }

  void OnPushPromise(SpdyStreamId stream_id,
                     SpdyStreamId promised_stream_id,
                     bool end) override {
    if (!stream_->supports_push_promise()) {
      CloseConnection("PUSH_PROMISE not supported.");
      return;
    }
    if (!stream_->IsConnected()) {
      return;
    }
    stream_->OnPushPromise(stream_id, promised_stream_id, end);
  }

  void OnContinuation(SpdyStreamId stream_id, bool end) override {}

  void OnPriority(SpdyStreamId stream_id,
                  SpdyStreamId parent_id,
                  int weight,
                  bool exclusive) override {
    CloseConnection("SPDY PRIORITY frame received.");
  }

  bool OnUnknownFrame(SpdyStreamId stream_id, int frame_type) override {
    CloseConnection("Unknown frame type received.");
    return false;
  }

  // SpdyFramerDebugVisitorInterface implementation
  void OnSendCompressedFrame(SpdyStreamId stream_id,
                             SpdyFrameType type,
                             size_t payload_len,
                             size_t frame_len) override {
    if (payload_len == 0) {
      QUIC_BUG << "Zero payload length.";
      return;
    }
    int compression_pct = 100 - (100 * frame_len) / payload_len;
    DVLOG(1) << "Net.QuicHpackCompressionPercentage: " << compression_pct;
    UMA_HISTOGRAM_PERCENTAGE("Net.QuicHpackCompressionPercentage",
                             compression_pct);
  }

  void OnReceiveCompressedFrame(SpdyStreamId stream_id,
                                SpdyFrameType type,
                                size_t frame_len) override {
    if (stream_->IsConnected()) {
      stream_->OnCompressedFrameSize(frame_len);
    }
  }

  void set_max_uncompressed_header_bytes(
      size_t set_max_uncompressed_header_bytes) {
    header_list_.set_max_uncompressed_header_bytes(
        set_max_uncompressed_header_bytes);
  }

 private:
  void CloseConnection(const std::string& details) {
    if (stream_->IsConnected()) {
      stream_->CloseConnectionWithDetails(QUIC_INVALID_HEADERS_STREAM_DATA,
                                          details);
    }
  }

 private:
  QuicHeadersStream* stream_;
  QuicHeaderList header_list_;

  DISALLOW_COPY_AND_ASSIGN(SpdyFramerVisitor);
};

QuicHeadersStream::QuicHeadersStream(QuicSpdySession* session)
    : QuicStream(kHeadersStreamId, session),
      spdy_session_(session),
      stream_id_(kInvalidStreamId),
      promised_stream_id_(kInvalidStreamId),
      fin_(false),
      frame_len_(0),
      uncompressed_frame_len_(0),
      supports_push_promise_(session->perspective() == Perspective::IS_CLIENT),
      cur_max_timestamp_(QuicTime::Zero()),
      prev_max_timestamp_(QuicTime::Zero()),
      spdy_framer_(HTTP2),
      spdy_framer_visitor_(new SpdyFramerVisitor(this)) {
  spdy_framer_.set_visitor(spdy_framer_visitor_.get());
  spdy_framer_.set_debug_visitor(spdy_framer_visitor_.get());
  // The headers stream is exempt from connection level flow control.
  DisableConnectionFlowControlForThisStream();
}

QuicHeadersStream::~QuicHeadersStream() {}

size_t QuicHeadersStream::WriteHeaders(QuicStreamId stream_id,
                                       SpdyHeaderBlock headers,
                                       bool fin,
                                       SpdyPriority priority,
                                       QuicAckListenerInterface* ack_listener) {
  SpdyHeadersIR headers_frame(stream_id, std::move(headers));
  headers_frame.set_fin(fin);
  if (session()->perspective() == Perspective::IS_CLIENT) {
    headers_frame.set_has_priority(true);
    headers_frame.set_weight(Spdy3PriorityToHttp2Weight(priority));
  }
  SpdySerializedFrame frame(spdy_framer_.SerializeFrame(headers_frame));
  WriteOrBufferData(StringPiece(frame.data(), frame.size()), false,
                    ack_listener);
  return frame.size();
}

size_t QuicHeadersStream::WritePushPromise(QuicStreamId original_stream_id,
                                           QuicStreamId promised_stream_id,
                                           SpdyHeaderBlock headers) {
  if (session()->perspective() == Perspective::IS_CLIENT) {
    QUIC_BUG << "Client shouldn't send PUSH_PROMISE";
    return 0;
  }

  SpdyPushPromiseIR push_promise(original_stream_id, promised_stream_id,
                                 std::move(headers));

  // PUSH_PROMISE must not be the last frame sent out, at least followed by
  // response headers.
  push_promise.set_fin(false);

  SpdySerializedFrame frame(spdy_framer_.SerializeFrame(push_promise));
  WriteOrBufferData(StringPiece(frame.data(), frame.size()), false, nullptr);
  return frame.size();
}

QuicConsumedData QuicHeadersStream::WritevStreamData(
    QuicStreamId id,
    QuicIOVector iov,
    QuicStreamOffset offset,
    bool fin,
    QuicAckListenerInterface* ack_notifier_delegate) {
  const size_t max_len = kSpdyInitialFrameSizeLimit -
                         SpdyConstants::GetDataFrameMinimumSize(HTTP2);

  QuicConsumedData result(0, false);
  size_t total_length = iov.total_length;

  // Encapsulate the data into HTTP/2 DATA frames.  The outer loop
  // handles each element of the source iov, the inner loop handles
  // the possibility of fragmenting eacho of those into multiple DATA
  // frames, as the DATA frames have a max size of 16KB.
  for (int i = 0; i < iov.iov_count; i++) {
    size_t offset = 0;
    const struct iovec* src_iov = &iov.iov[i];
    do {
      size_t len =
          std::min(std::min(src_iov->iov_len - offset, max_len), total_length);
      char* data = static_cast<char*>(src_iov->iov_base) + offset;
      SpdyDataIR spdy_data(id, StringPiece(data, len));
      offset += len;
      // fin handling, set it only it only very last generated HTTP/2
      // DATA frame.
      bool last_iov = i == iov.iov_count - 1;
      bool last_fragment_within_iov = offset >= src_iov->iov_len;
      bool frame_fin = (last_iov && last_fragment_within_iov) ? fin : false;
      spdy_data.set_fin(frame_fin);
      if (frame_fin) {
        result.fin_consumed = true;
      }
      SpdySerializedFrame frame(spdy_framer_.SerializeFrame(spdy_data));
      DVLOG(1) << "Encapsulating in DATA frame for stream " << id << " len "
               << len << " fin " << spdy_data.fin() << " remaining "
               << src_iov->iov_len - offset;

      scoped_refptr<ForceHolAckListener> ack_listener;
      if (ack_notifier_delegate != nullptr) {
        ack_listener =
            new ForceHolAckListener(ack_notifier_delegate, frame.size() - len);
      }

      WriteOrBufferData(StringPiece(frame.data(), frame.size()), false,
                        ack_listener.get());
      result.bytes_consumed += len;
      total_length -= len;
      if (total_length <= 0) {
        return result;
      }
    } while (offset < src_iov->iov_len);
  }
  return result;
}

void QuicHeadersStream::OnDataAvailable() {
  char buffer[1024];
  struct iovec iov;
  QuicTime timestamp(QuicTime::Zero());
  while (true) {
    iov.iov_base = buffer;
    iov.iov_len = arraysize(buffer);
    if (!sequencer()->GetReadableRegion(&iov, &timestamp)) {
      // No more data to read.
      break;
    }
    DCHECK(timestamp.IsInitialized());
    cur_max_timestamp_ = std::max(timestamp, cur_max_timestamp_);
    if (spdy_framer_.ProcessInput(static_cast<char*>(iov.iov_base),
                                  iov.iov_len) != iov.iov_len) {
      // Error processing data.
      return;
    }
    sequencer()->MarkConsumed(iov.iov_len);
    MaybeReleaseSequencerBuffer();
  }
}

void QuicHeadersStream::set_max_uncompressed_header_bytes(
    size_t set_max_uncompressed_header_bytes) {
  spdy_framer_visitor_->set_max_uncompressed_header_bytes(
      set_max_uncompressed_header_bytes);
}

void QuicHeadersStream::OnHeaders(SpdyStreamId stream_id,
                                  bool has_priority,
                                  SpdyPriority priority,
                                  bool fin) {
  if (has_priority) {
    if (session()->perspective() == Perspective::IS_CLIENT) {
      CloseConnectionWithDetails(QUIC_INVALID_HEADERS_STREAM_DATA,
                                 "Server must not send priorities.");
      return;
    }
    spdy_session_->OnStreamHeadersPriority(stream_id, priority);
  } else {
    if (session()->perspective() == Perspective::IS_SERVER) {
      CloseConnectionWithDetails(QUIC_INVALID_HEADERS_STREAM_DATA,
                                 "Client must send priorities.");
      return;
    }
  }
  DCHECK_EQ(kInvalidStreamId, stream_id_);
  DCHECK_EQ(kInvalidStreamId, promised_stream_id_);
  stream_id_ = stream_id;
  fin_ = fin;
}

void QuicHeadersStream::OnPushPromise(SpdyStreamId stream_id,
                                      SpdyStreamId promised_stream_id,
                                      bool end) {
  DCHECK_EQ(kInvalidStreamId, stream_id_);
  DCHECK_EQ(kInvalidStreamId, promised_stream_id_);
  stream_id_ = stream_id;
  promised_stream_id_ = promised_stream_id;
}

void QuicHeadersStream::OnHeaderList(const QuicHeaderList& header_list) {
  DVLOG(1) << "Received header list for stream " << stream_id_ << ": "
           << header_list.DebugString();
  if (prev_max_timestamp_ > cur_max_timestamp_) {
    // prev_max_timestamp_ > cur_max_timestamp_ implies that
    // headers from lower numbered streams actually came off the
    // wire after headers for the current stream, hence there was
    // HOL blocking.
    QuicTime::Delta delta = prev_max_timestamp_ - cur_max_timestamp_;
    DVLOG(1) << "stream " << stream_id_
             << ": Net.QuicSession.HeadersHOLBlockedTime "
             << delta.ToMilliseconds();
    spdy_session_->OnHeadersHeadOfLineBlocking(delta);
  }

  prev_max_timestamp_ = std::max(prev_max_timestamp_, cur_max_timestamp_);
  cur_max_timestamp_ = QuicTime::Zero();
  if (promised_stream_id_ == kInvalidStreamId) {
    spdy_session_->OnStreamHeaderList(stream_id_, fin_, frame_len_,
                                      header_list);
  } else {
    spdy_session_->OnPromiseHeaderList(stream_id_, promised_stream_id_,
                                       frame_len_, header_list);
  }
  // Reset state for the next frame.
  promised_stream_id_ = kInvalidStreamId;
  stream_id_ = kInvalidStreamId;
  fin_ = false;
  frame_len_ = 0;
  uncompressed_frame_len_ = 0;
}

void QuicHeadersStream::OnCompressedFrameSize(size_t frame_len) {
  frame_len_ += frame_len;
}

bool QuicHeadersStream::IsConnected() {
  return session()->connection()->connected();
}

void QuicHeadersStream::DisableHpackDynamicTable() {
  spdy_framer_.UpdateHeaderEncoderTableSize(0);
}

void QuicHeadersStream::SetHpackEncoderDebugVisitor(
    std::unique_ptr<HpackDebugVisitor> visitor) {
  spdy_framer_.SetEncoderHeaderTableDebugVisitor(
      std::unique_ptr<HeaderTableDebugVisitor>(new HeaderTableDebugVisitor(
          session()->connection()->helper()->GetClock(), std::move(visitor))));
}

void QuicHeadersStream::SetHpackDecoderDebugVisitor(
    std::unique_ptr<HpackDebugVisitor> visitor) {
  spdy_framer_.SetDecoderHeaderTableDebugVisitor(
      std::unique_ptr<HeaderTableDebugVisitor>(new HeaderTableDebugVisitor(
          session()->connection()->helper()->GetClock(), std::move(visitor))));
}

void QuicHeadersStream::UpdateHeaderEncoderTableSize(uint32_t value) {
  spdy_framer_.UpdateHeaderEncoderTableSize(value);
}

void QuicHeadersStream::UpdateEnableServerPush(bool value) {
  spdy_session_->set_server_push_enabled(value);
}

void QuicHeadersStream::MaybeReleaseSequencerBuffer() {
  if (FLAGS_quic_headers_stream_release_sequencer_buffer &&
      spdy_session_->ShouldReleaseHeadersStreamSequencerBuffer()) {
    sequencer()->ReleaseBufferIfEmpty();
  }
}

bool QuicHeadersStream::OnDataFrameHeader(QuicStreamId stream_id,
                                          size_t length,
                                          bool fin) {
  if (!spdy_session_->force_hol_blocking()) {
    return false;
  }
  if (!IsConnected()) {
    return true;
  }
  DVLOG(1) << "DATA frame header for stream " << stream_id << " length "
           << length << " fin " << fin;
  fin_ = fin;
  frame_len_ = length;
  if (fin && length == 0) {
    OnStreamFrameData(stream_id, "", 0);
  }
  return true;
}

bool QuicHeadersStream::OnStreamFrameData(QuicStreamId stream_id,
                                          const char* data,
                                          size_t len) {
  if (!spdy_session_->force_hol_blocking()) {
    return false;
  }
  if (!IsConnected()) {
    return true;
  }
  frame_len_ -= len;
  // Ignore fin_ while there is more data coming, if frame_len_ > 0.
  spdy_session_->OnStreamFrameData(stream_id, data, len,
                                   frame_len_ > 0 ? false : fin_);
  return true;
}

}  // namespace net