net/quic/quic_stream_sequencer.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/quic_stream_sequencer.h"
   6
   7 #include <algorithm>
   8 #include <limits>
   9 #include <utility>
  10
  11 #include "base/logging.h"
  12 #include "net/quic/reliable_quic_stream.h"
  13
  14 using std::min;
  15 using std::numeric_limits;
  16 using std::string;
  17
  18 namespace net {
  19
  20 QuicStreamSequencer::FrameData::FrameData(QuicStreamOffset offset,
  21                                           string segment)
  22     : offset(offset), segment(segment) {}
  23
  24 QuicStreamSequencer::QuicStreamSequencer(ReliableQuicStream* quic_stream)
  25     : stream_(quic_stream),
  26       num_bytes_consumed_(0),
  27       close_offset_(numeric_limits<QuicStreamOffset>::max()),
  28       blocked_(false),
  29       num_bytes_buffered_(0),
  30       num_frames_received_(0),
  31       num_duplicate_frames_received_(0),
  32       num_early_frames_received_(0) {
  33 }
  34
  35 QuicStreamSequencer::~QuicStreamSequencer() {
  36 }
  37
  38 void QuicStreamSequencer::OnStreamFrame(const QuicStreamFrame& frame) {
  39   ++num_frames_received_;
  40   FrameList::iterator insertion_point = FindInsertionPoint(frame);
  41   if (IsDuplicate(frame, insertion_point)) {
  42     ++num_duplicate_frames_received_;
  43     // Silently ignore duplicates.
  44     return;
  45   }
  46
  47   if (FrameOverlapsBufferedData(frame, insertion_point)) {
  48     stream_->CloseConnectionWithDetails(
  49         QUIC_INVALID_STREAM_FRAME, "Stream frame overlaps with buffered data.");
  50     return;
  51   }
  52
  53   const QuicStreamOffset byte_offset = frame.offset;
  54   const size_t data_len = frame.data.length();
  55   if (data_len == 0 && !frame.fin) {
  56     // Stream frames must have data or a fin flag.
  57     stream_->CloseConnectionWithDetails(QUIC_INVALID_STREAM_FRAME,
  58                                         "Empty stream frame without FIN set.");
  59     return;
  60   }
  61
  62   if (frame.fin) {
  63     CloseStreamAtOffset(frame.offset + data_len);
  64     if (data_len == 0) {
  65       return;
  66     }
  67   }
  68
  69   if (byte_offset > num_bytes_consumed_) {
  70     ++num_early_frames_received_;
  71   }
  72
  73   DVLOG(1) << "Buffering stream data at offset " << byte_offset;
  74   // Inserting an empty string and then copying to avoid the extra copy.
  75   insertion_point =
  76       buffered_frames_.insert(insertion_point, FrameData(byte_offset, ""));
  77   frame.data.CopyToString(&insertion_point->segment);
  78   num_bytes_buffered_ += data_len;
  79
  80   if (blocked_) {
  81     return;
  82   }
  83
  84   if (byte_offset == num_bytes_consumed_) {
  85     stream_->OnDataAvailable();
  86   }
  87 }
  88
  89 void QuicStreamSequencer::CloseStreamAtOffset(QuicStreamOffset offset) {
  90   const QuicStreamOffset kMaxOffset = numeric_limits<QuicStreamOffset>::max();
  91
  92   // If there is a scheduled close, the new offset should match it.
  93   if (close_offset_ != kMaxOffset && offset != close_offset_) {
  94     stream_->Reset(QUIC_MULTIPLE_TERMINATION_OFFSETS);
  95     return;
  96   }
  97
  98   close_offset_ = offset;
  99
 100   MaybeCloseStream();
 101 }
 102
 103 bool QuicStreamSequencer::MaybeCloseStream() {
 104   if (!blocked_ && IsClosed()) {
 105     DVLOG(1) << "Passing up termination, as we've processed "
 106              << num_bytes_consumed_ << " of " << close_offset_
 107              << " bytes.";
 108     // This will cause the stream to consume the fin.
 109     // Technically it's an error if num_bytes_consumed isn't exactly
 110     // equal, but error handling seems silly at this point.
 111     stream_->OnDataAvailable();
 112     buffered_frames_.clear();
 113     num_bytes_buffered_ = 0;
 114     return true;
 115   }
 116   return false;
 117 }
 118
 119 int QuicStreamSequencer::GetReadableRegions(iovec* iov, size_t iov_len) const {
 120   DCHECK(!blocked_);
 121   FrameList::const_iterator it = buffered_frames_.begin();
 122   size_t index = 0;
 123   QuicStreamOffset offset = num_bytes_consumed_;
 124   while (it != buffered_frames_.end() && index < iov_len) {
 125     if (it->offset != offset) {
 126       return index;
 127     }
 128
 129     iov[index].iov_base =
 130         static_cast<void*>(const_cast<char*>(it->segment.data()));
 131     iov[index].iov_len = it->segment.size();
 132     offset += it->segment.size();
 133
 134     ++index;
 135     ++it;
 136   }
 137   return index;
 138 }
 139
 140 int QuicStreamSequencer::Readv(const struct iovec* iov, size_t iov_len) {
 141   DCHECK(!blocked_);
 142   FrameList::iterator it = buffered_frames_.begin();
 143   size_t iov_index = 0;
 144   size_t iov_offset = 0;
 145   size_t frame_offset = 0;
 146   QuicStreamOffset initial_bytes_consumed = num_bytes_consumed_;
 147
 148   while (iov_index < iov_len && it != buffered_frames_.end() &&
 149          it->offset == num_bytes_consumed_) {
 150     int bytes_to_read = min(iov[iov_index].iov_len - iov_offset,
 151                             it->segment.size() - frame_offset);
 152
 153     char* iov_ptr = static_cast<char*>(iov[iov_index].iov_base) + iov_offset;
 154     memcpy(iov_ptr, it->segment.data() + frame_offset, bytes_to_read);
 155     frame_offset += bytes_to_read;
 156     iov_offset += bytes_to_read;
 157
 158     if (iov[iov_index].iov_len == iov_offset) {
 159       // We've filled this buffer.
 160       iov_offset = 0;
 161       ++iov_index;
 162     }
 163     if (it->segment.size() == frame_offset) {
 164       // We've copied this whole frame
 165       RecordBytesConsumed(it->segment.size());
 166       buffered_frames_.erase(it);
 167       it = buffered_frames_.begin();
 168       frame_offset = 0;
 169     }
 170   }
 171   // Done copying.  If there is a partial frame, update it.
 172   if (frame_offset != 0) {
 173     buffered_frames_.push_front(
 174         FrameData(it->offset + frame_offset, it->segment.substr(frame_offset)));
 175     buffered_frames_.erase(it);
 176     RecordBytesConsumed(frame_offset);
 177   }
 178   return static_cast<int>(num_bytes_consumed_ - initial_bytes_consumed);
 179 }
 180
 181 bool QuicStreamSequencer::HasBytesToRead() const {
 182   return !buffered_frames_.empty() &&
 183          buffered_frames_.begin()->offset == num_bytes_consumed_;
 184 }
 185
 186 bool QuicStreamSequencer::IsClosed() const {
 187   return num_bytes_consumed_ >= close_offset_;
 188 }
 189
 190 QuicStreamSequencer::FrameList::iterator
 191 QuicStreamSequencer::FindInsertionPoint(const QuicStreamFrame& frame) {
 192   if (buffered_frames_.empty()) {
 193     return buffered_frames_.begin();
 194   }
 195   // If it's after all buffered_frames, return the end.
 196   if (frame.offset >= (buffered_frames_.rbegin()->offset +
 197                        buffered_frames_.rbegin()->segment.length())) {
 198     return buffered_frames_.end();
 199   }
 200   FrameList::iterator iter = buffered_frames_.begin();
 201   // Only advance the iterator if the data begins after the already received
 202   // frame.  If the new frame overlaps with an existing frame, the iterator will
 203   // still point to the frame it overlaps with.
 204   while (iter != buffered_frames_.end() &&
 205          frame.offset >= iter->offset + iter->segment.length()) {
 206     ++iter;
 207   }
 208   return iter;
 209 }
 210
 211 bool QuicStreamSequencer::FrameOverlapsBufferedData(
 212     const QuicStreamFrame& frame,
 213     FrameList::const_iterator insertion_point) const {
 214   if (buffered_frames_.empty() || insertion_point == buffered_frames_.end()) {
 215     return false;
 216   }
 217   // If there is a buffered frame with a higher starting offset, then check to
 218   // see if the new frame overlaps the beginning of the higher frame.
 219   if (frame.offset < insertion_point->offset &&
 220       frame.offset + frame.data.length() > insertion_point->offset) {
 221     DVLOG(1) << "New frame overlaps next frame: " << frame.offset << " + "
 222              << frame.data.size() << " > " << insertion_point->offset;
 223     return true;
 224   }
 225   // If there is a buffered frame with a lower starting offset, then check to
 226   // see if the buffered frame runs into the new frame.
 227   if (frame.offset >= insertion_point->offset &&
 228       frame.offset <
 229           insertion_point->offset + insertion_point->segment.length()) {
 230     DVLOG(1) << "Preceeding frame overlaps new frame: "
 231              << insertion_point->offset << " + "
 232              << insertion_point->segment.length() << " > " << frame.offset;
 233     return true;
 234   }
 235
 236   return false;
 237 }
 238
 239 void QuicStreamSequencer::MarkConsumed(size_t num_bytes_consumed) {
 240   DCHECK(!blocked_);
 241   size_t end_offset = num_bytes_consumed_ + num_bytes_consumed;
 242   while (!buffered_frames_.empty() && end_offset != num_bytes_consumed_) {
 243     FrameList::iterator it = buffered_frames_.begin();
 244     if (it->offset != num_bytes_consumed_) {
 245       LOG(DFATAL) << "Invalid argument to MarkConsumed. "
 246                   << " num_bytes_consumed_: " << num_bytes_consumed_
 247                   << " end_offset: " << end_offset << " offset: " << it->offset
 248                   << " length: " << it->segment.length();
 249       stream_->Reset(QUIC_ERROR_PROCESSING_STREAM);
 250       return;
 251     }
 252
 253     if (it->offset + it->segment.length() <= end_offset) {
 254       RecordBytesConsumed(it->segment.length());
 255       // This chunk is entirely consumed.
 256       buffered_frames_.erase(it);
 257       continue;
 258     }
 259
 260     // Partially consume this frame.
 261     size_t delta = end_offset - it->offset;
 262     RecordBytesConsumed(delta);
 263     string new_data = it->segment.substr(delta);
 264     buffered_frames_.erase(it);
 265     buffered_frames_.push_front(FrameData(num_bytes_consumed_, new_data));
 266     break;
 267   }
 268 }
 269
 270 bool QuicStreamSequencer::IsDuplicate(
 271     const QuicStreamFrame& frame,
 272     FrameList::const_iterator insertion_point) const {
 273   // A frame is duplicate if the frame offset is smaller than the bytes consumed
 274   // or identical to an already received frame.
 275   return frame.offset < num_bytes_consumed_ ||
 276          (insertion_point != buffered_frames_.end() &&
 277           frame.offset == insertion_point->offset);
 278 }
 279
 280 void QuicStreamSequencer::SetBlockedUntilFlush() {
 281   blocked_ = true;
 282 }
 283
 284 void QuicStreamSequencer::SetUnblocked() {
 285   blocked_ = false;
 286   if (IsClosed() || HasBytesToRead()) {
 287     stream_->OnDataAvailable();
 288   }
 289 }
 290
 291 void QuicStreamSequencer::RecordBytesConsumed(size_t bytes_consumed) {
 292   num_bytes_consumed_ += bytes_consumed;
 293   num_bytes_buffered_ -= bytes_consumed;
 294
 295   stream_->AddBytesConsumed(bytes_consumed);
 296 }
 297
 298 }  // namespace net