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::QuicStreamSequencer(ReliableQuicStream* quic_stream)
  21     : stream_(quic_stream),
  22       num_bytes_consumed_(0),
  23       close_offset_(numeric_limits<QuicStreamOffset>::max()),
  24       blocked_(false),
  25       num_bytes_buffered_(0),
  26       num_frames_received_(0),
  27       num_duplicate_frames_received_(0),
  28       num_early_frames_received_(0) {
  29 }
  30
  31 QuicStreamSequencer::~QuicStreamSequencer() {
  32 }
  33
  34 void QuicStreamSequencer::OnStreamFrame(const QuicStreamFrame& frame) {
  35   ++num_frames_received_;
  36   if (IsDuplicate(frame)) {
  37     ++num_duplicate_frames_received_;
  38     // Silently ignore duplicates.
  39     return;
  40   }
  41
  42   if (FrameOverlapsBufferedData(frame)) {
  43     stream_->CloseConnectionWithDetails(
  44         QUIC_INVALID_STREAM_FRAME, "Stream frame overlaps with buffered data.");
  45     return;
  46   }
  47
  48   const QuicStreamOffset byte_offset = frame.offset;
  49   const size_t data_len = frame.data.length();
  50   if (data_len == 0 && !frame.fin) {
  51     // Stream frames must have data or a fin flag.
  52     stream_->CloseConnectionWithDetails(QUIC_INVALID_STREAM_FRAME,
  53                                         "Empty stream frame without FIN set.");
  54     return;
  55   }
  56
  57   if (frame.fin) {
  58     CloseStreamAtOffset(frame.offset + data_len);
  59     if (data_len == 0) {
  60       return;
  61     }
  62   }
  63
  64   if (byte_offset > num_bytes_consumed_) {
  65     ++num_early_frames_received_;
  66   }
  67
  68   // If the frame has arrived in-order then we can process it immediately, only
  69   // buffering if the stream is unable to process it.
  70   size_t bytes_consumed = 0;
  71   if (!blocked_ && byte_offset == num_bytes_consumed_) {
  72     DVLOG(1) << "Processing byte offset " << byte_offset;
  73     bytes_consumed =
  74         stream_->ProcessRawData(frame.data.data(), frame.data.length());
  75     num_bytes_consumed_ += bytes_consumed;
  76     stream_->AddBytesConsumed(bytes_consumed);
  77
  78     if (MaybeCloseStream()) {
  79       return;
  80     }
  81     if (bytes_consumed > data_len) {
  82       stream_->Reset(QUIC_ERROR_PROCESSING_STREAM);
  83       return;
  84     } else if (bytes_consumed == data_len) {
  85       FlushBufferedFrames();
  86       return;  // it's safe to ack this frame.
  87     }
  88   }
  89
  90   // Buffer any remaining data to be consumed by the stream when ready.
  91   if (bytes_consumed < data_len) {
  92     DVLOG(1) << "Buffering stream data at offset " << byte_offset;
  93     const size_t remaining_length = data_len - bytes_consumed;
  94     buffered_frames_.insert(std::make_pair(
  95         byte_offset + bytes_consumed,
  96         string(frame.data.data() + bytes_consumed, remaining_length)));
  97     num_bytes_buffered_ += remaining_length;
  98   }
  99 }
 100
 101 void QuicStreamSequencer::CloseStreamAtOffset(QuicStreamOffset offset) {
 102   const QuicStreamOffset kMaxOffset = numeric_limits<QuicStreamOffset>::max();
 103
 104   // If we have a scheduled termination or close, any new offset should match
 105   // it.
 106   if (close_offset_ != kMaxOffset && offset != close_offset_) {
 107     stream_->Reset(QUIC_MULTIPLE_TERMINATION_OFFSETS);
 108     return;
 109   }
 110
 111   close_offset_ = offset;
 112
 113   MaybeCloseStream();
 114 }
 115
 116 bool QuicStreamSequencer::MaybeCloseStream() {
 117   if (!blocked_ && IsClosed()) {
 118     DVLOG(1) << "Passing up termination, as we've processed "
 119              << num_bytes_consumed_ << " of " << close_offset_
 120              << " bytes.";
 121     // Technically it's an error if num_bytes_consumed isn't exactly
 122     // equal, but error handling seems silly at this point.
 123     stream_->OnFinRead();
 124     buffered_frames_.clear();
 125     num_bytes_buffered_ = 0;
 126     return true;
 127   }
 128   return false;
 129 }
 130
 131 int QuicStreamSequencer::GetReadableRegions(iovec* iov, size_t iov_len) {
 132   DCHECK(!blocked_);
 133   FrameMap::iterator it = buffered_frames_.begin();
 134   size_t index = 0;
 135   QuicStreamOffset offset = num_bytes_consumed_;
 136   while (it != buffered_frames_.end() && index < iov_len) {
 137     if (it->first != offset) return index;
 138
 139     iov[index].iov_base = static_cast<void*>(
 140         const_cast<char*>(it->second.data()));
 141     iov[index].iov_len = it->second.size();
 142     offset += it->second.size();
 143
 144     ++index;
 145     ++it;
 146   }
 147   return index;
 148 }
 149
 150 int QuicStreamSequencer::Readv(const struct iovec* iov, size_t iov_len) {
 151   DCHECK(!blocked_);
 152   FrameMap::iterator it = buffered_frames_.begin();
 153   size_t iov_index = 0;
 154   size_t iov_offset = 0;
 155   size_t frame_offset = 0;
 156   QuicStreamOffset initial_bytes_consumed = num_bytes_consumed_;
 157
 158   while (iov_index < iov_len &&
 159          it != buffered_frames_.end() &&
 160          it->first == num_bytes_consumed_) {
 161     int bytes_to_read = min(iov[iov_index].iov_len - iov_offset,
 162                             it->second.size() - frame_offset);
 163
 164     char* iov_ptr = static_cast<char*>(iov[iov_index].iov_base) + iov_offset;
 165     memcpy(iov_ptr,
 166            it->second.data() + frame_offset, bytes_to_read);
 167     frame_offset += bytes_to_read;
 168     iov_offset += bytes_to_read;
 169
 170     if (iov[iov_index].iov_len == iov_offset) {
 171       // We've filled this buffer.
 172       iov_offset = 0;
 173       ++iov_index;
 174     }
 175     if (it->second.size() == frame_offset) {
 176       // We've copied this whole frame
 177       RecordBytesConsumed(it->second.size());
 178       buffered_frames_.erase(it);
 179       it = buffered_frames_.begin();
 180       frame_offset = 0;
 181     }
 182   }
 183   // We've finished copying.  If we have a partial frame, update it.
 184   if (frame_offset != 0) {
 185     buffered_frames_.insert(std::make_pair(it->first + frame_offset,
 186                                            it->second.substr(frame_offset)));
 187     buffered_frames_.erase(buffered_frames_.begin());
 188     RecordBytesConsumed(frame_offset);
 189   }
 190   return static_cast<int>(num_bytes_consumed_ - initial_bytes_consumed);
 191 }
 192
 193 bool QuicStreamSequencer::HasBytesToRead() const {
 194   FrameMap::const_iterator it = buffered_frames_.begin();
 195
 196   return it != buffered_frames_.end() && it->first == num_bytes_consumed_;
 197 }
 198
 199 bool QuicStreamSequencer::IsClosed() const {
 200   return num_bytes_consumed_ >= close_offset_;
 201 }
 202
 203 bool QuicStreamSequencer::FrameOverlapsBufferedData(
 204     const QuicStreamFrame& frame) const {
 205   if (buffered_frames_.empty()) {
 206     return false;
 207   }
 208
 209   FrameMap::const_iterator next_frame =
 210       buffered_frames_.lower_bound(frame.offset);
 211   // Duplicate frames should have been dropped in IsDuplicate.
 212   DCHECK(next_frame == buffered_frames_.end() ||
 213          next_frame->first != frame.offset);
 214
 215   // If there is a buffered frame with a higher starting offset, then we check
 216   // to see if the new frame runs into the higher frame.
 217   if (next_frame != buffered_frames_.end() &&
 218       (frame.offset + frame.data.size()) > next_frame->first) {
 219     DVLOG(1) << "New frame overlaps next frame: " << frame.offset << " + "
 220              << frame.data.size() << " > " << next_frame->first;
 221     return true;
 222   }
 223
 224   // If there is a buffered frame with a lower starting offset, then we check
 225   // to see if the buffered frame runs into the new frame.
 226   if (next_frame != buffered_frames_.begin()) {
 227     FrameMap::const_iterator preceeding_frame = --next_frame;
 228     QuicStreamOffset offset = preceeding_frame->first;
 229     uint64 data_length = preceeding_frame->second.length();
 230     if ((offset + data_length) > frame.offset) {
 231       DVLOG(1) << "Preceeding frame overlaps new frame: " << offset << " + "
 232                << data_length << " > " << frame.offset;
 233       return true;
 234     }
 235   }
 236   return false;
 237 }
 238
 239 bool QuicStreamSequencer::IsDuplicate(const QuicStreamFrame& frame) const {
 240   // A frame is duplicate if the frame offset is smaller than our bytes consumed
 241   // or we have stored the frame in our map.
 242   // TODO(pwestin): Is it possible that a new frame contain more data even if
 243   // the offset is the same?
 244   return frame.offset < num_bytes_consumed_ ||
 245       buffered_frames_.find(frame.offset) != buffered_frames_.end();
 246 }
 247
 248 void QuicStreamSequencer::SetBlockedUntilFlush() {
 249   blocked_ = true;
 250 }
 251
 252 void QuicStreamSequencer::FlushBufferedFrames() {
 253   blocked_ = false;
 254   FrameMap::iterator it = buffered_frames_.find(num_bytes_consumed_);
 255   while (it != buffered_frames_.end()) {
 256     DVLOG(1) << "Flushing buffered packet at offset " << it->first;
 257     string* data = &it->second;
 258     size_t bytes_consumed = stream_->ProcessRawData(data->c_str(),
 259                                                     data->size());
 260     RecordBytesConsumed(bytes_consumed);
 261     if (MaybeCloseStream()) {
 262       return;
 263     }
 264     if (bytes_consumed > data->size()) {
 265       stream_->Reset(QUIC_ERROR_PROCESSING_STREAM);  // Programming error
 266       return;
 267     } else if (bytes_consumed == data->size()) {
 268       buffered_frames_.erase(it);
 269       it = buffered_frames_.find(num_bytes_consumed_);
 270     } else {
 271       string new_data = it->second.substr(bytes_consumed);
 272       buffered_frames_.erase(it);
 273       buffered_frames_.insert(std::make_pair(num_bytes_consumed_, new_data));
 274       return;
 275     }
 276   }
 277   MaybeCloseStream();
 278 }
 279
 280 void QuicStreamSequencer::RecordBytesConsumed(size_t bytes_consumed) {
 281   num_bytes_consumed_ += bytes_consumed;
 282   num_bytes_buffered_ -= bytes_consumed;
 283
 284   stream_->AddBytesConsumed(bytes_consumed);
 285 }
 286
 287 }  // namespace net