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
  10 #include "base/logging.h"
  11 #include "net/quic/reliable_quic_stream.h"
  12
  13 using std::min;
  14 using std::numeric_limits;
  15
  16 namespace net {
  17
  18 QuicStreamSequencer::QuicStreamSequencer(ReliableQuicStream* quic_stream)
  19     : stream_(quic_stream),
  20       num_bytes_consumed_(0),
  21       max_frame_memory_(numeric_limits<size_t>::max()),
  22       close_offset_(numeric_limits<QuicStreamOffset>::max()),
  23       blocked_(false),
  24       num_bytes_buffered_(0) {
  25 }
  26
  27 QuicStreamSequencer::QuicStreamSequencer(size_t max_frame_memory,
  28                                          ReliableQuicStream* quic_stream)
  29     : stream_(quic_stream),
  30       num_bytes_consumed_(0),
  31       max_frame_memory_(max_frame_memory),
  32       close_offset_(numeric_limits<QuicStreamOffset>::max()),
  33       blocked_(false),
  34       num_bytes_buffered_(0) {
  35   if (max_frame_memory < kMaxPacketSize) {
  36     LOG(DFATAL) << "Setting max frame memory to " << max_frame_memory
  37                 << ".  Some frames will be impossible to handle.";
  38   }
  39 }
  40
  41 QuicStreamSequencer::~QuicStreamSequencer() {
  42 }
  43
  44 bool QuicStreamSequencer::WillAcceptStreamFrame(
  45     const QuicStreamFrame& frame) const {
  46   size_t data_len = frame.data.TotalBufferSize();
  47   if (data_len > max_frame_memory_) {
  48     LOG(DFATAL) << "data_len: " << data_len << " > max_frame_memory_: "
  49                 << max_frame_memory_;
  50     return false;
  51   }
  52
  53   if (IsDuplicate(frame)) {
  54     return true;
  55   }
  56   QuicStreamOffset byte_offset = frame.offset;
  57   if (data_len > max_frame_memory_) {
  58     // We're never going to buffer this frame and we can't pass it up.
  59     // The stream might only consume part of it and we'd need a partial ack.
  60     //
  61     // Ideally this should never happen, as we check that
  62     // max_frame_memory_ > kMaxPacketSize and lower levels should reject
  63     // frames larger than that.
  64     return false;
  65   }
  66   if (byte_offset + data_len - num_bytes_consumed_ > max_frame_memory_) {
  67     // We can buffer this but not right now.  Toss it.
  68     // It might be worth trying an experiment where we try best-effort buffering
  69     return false;
  70   }
  71   return true;
  72 }
  73
  74 bool QuicStreamSequencer::OnStreamFrame(const QuicStreamFrame& frame) {
  75   if (!WillAcceptStreamFrame(frame)) {
  76     // This should not happen, as WillAcceptFrame should be called before
  77     // OnStreamFrame.  Error handling should be done by the caller.
  78     return false;
  79   }
  80   if (IsDuplicate(frame)) {
  81     // Silently ignore duplicates.
  82     return true;
  83   }
  84
  85   QuicStreamOffset byte_offset = frame.offset;
  86   size_t data_len = frame.data.TotalBufferSize();
  87   if (data_len == 0 && !frame.fin) {
  88     // Stream frames must have data or a fin flag.
  89     stream_->CloseConnectionWithDetails(QUIC_INVALID_STREAM_FRAME,
  90                                         "Empty stream frame without FIN set.");
  91     return false;
  92   }
  93
  94   if (frame.fin) {
  95     CloseStreamAtOffset(frame.offset + data_len);
  96     if (data_len == 0) {
  97       return true;
  98     }
  99   }
 100
 101   IOVector data;
 102   data.AppendIovec(frame.data.iovec(), frame.data.Size());
 103
 104   // If the frame has arrived in-order then we can process it immediately, only
 105   // buffering if the stream is unable to process it.
 106   if (!blocked_ && byte_offset == num_bytes_consumed_) {
 107     DVLOG(1) << "Processing byte offset " << byte_offset;
 108     size_t bytes_consumed = 0;
 109     for (size_t i = 0; i < data.Size(); ++i) {
 110       bytes_consumed += stream_->ProcessRawData(
 111           static_cast<char*>(data.iovec()[i].iov_base),
 112           data.iovec()[i].iov_len);
 113     }
 114     num_bytes_consumed_ += bytes_consumed;
 115     if (MaybeCloseStream()) {
 116       return true;
 117     }
 118     if (bytes_consumed > data_len) {
 119       stream_->Reset(QUIC_ERROR_PROCESSING_STREAM);
 120       return false;
 121     } else if (bytes_consumed == data_len) {
 122       FlushBufferedFrames();
 123       return true;  // it's safe to ack this frame.
 124     } else {
 125       // Set ourselves up to buffer what's left.
 126       data_len -= bytes_consumed;
 127       data.Consume(bytes_consumed);
 128       byte_offset += bytes_consumed;
 129     }
 130   }
 131
 132   // Buffer any remaining data to be consumed by the stream when ready.
 133   for (size_t i = 0; i < data.Size(); ++i) {
 134     DVLOG(1) << "Buffering stream data at offset " << byte_offset;
 135     const iovec& iov = data.iovec()[i];
 136     frames_.insert(make_pair(
 137         byte_offset, string(static_cast<char*>(iov.iov_base), iov.iov_len)));
 138     byte_offset += iov.iov_len;
 139     num_bytes_buffered_ += iov.iov_len;
 140   }
 141   return true;
 142 }
 143
 144 void QuicStreamSequencer::CloseStreamAtOffset(QuicStreamOffset offset) {
 145   const QuicStreamOffset kMaxOffset = numeric_limits<QuicStreamOffset>::max();
 146
 147   // If we have a scheduled termination or close, any new offset should match
 148   // it.
 149   if (close_offset_ != kMaxOffset && offset != close_offset_) {
 150     stream_->Reset(QUIC_MULTIPLE_TERMINATION_OFFSETS);
 151     return;
 152   }
 153
 154   close_offset_ = offset;
 155
 156   MaybeCloseStream();
 157 }
 158
 159 bool QuicStreamSequencer::MaybeCloseStream() {
 160   if (!blocked_ && IsClosed()) {
 161     DVLOG(1) << "Passing up termination, as we've processed "
 162              << num_bytes_consumed_ << " of " << close_offset_
 163              << " bytes.";
 164     // Technically it's an error if num_bytes_consumed isn't exactly
 165     // equal, but error handling seems silly at this point.
 166     stream_->OnFinRead();
 167     frames_.clear();
 168     num_bytes_buffered_ = 0;
 169     return true;
 170   }
 171   return false;
 172 }
 173
 174 int QuicStreamSequencer::GetReadableRegions(iovec* iov, size_t iov_len) {
 175   DCHECK(!blocked_);
 176   FrameMap::iterator it = frames_.begin();
 177   size_t index = 0;
 178   QuicStreamOffset offset = num_bytes_consumed_;
 179   while (it != frames_.end() && index < iov_len) {
 180     if (it->first != offset) return index;
 181
 182     iov[index].iov_base = static_cast<void*>(
 183         const_cast<char*>(it->second.data()));
 184     iov[index].iov_len = it->second.size();
 185     offset += it->second.size();
 186
 187     ++index;
 188     ++it;
 189   }
 190   return index;
 191 }
 192
 193 int QuicStreamSequencer::Readv(const struct iovec* iov, size_t iov_len) {
 194   DCHECK(!blocked_);
 195   FrameMap::iterator it = frames_.begin();
 196   size_t iov_index = 0;
 197   size_t iov_offset = 0;
 198   size_t frame_offset = 0;
 199   size_t initial_bytes_consumed = num_bytes_consumed_;
 200
 201   while (iov_index < iov_len &&
 202          it != frames_.end() &&
 203          it->first == num_bytes_consumed_) {
 204     int bytes_to_read = min(iov[iov_index].iov_len - iov_offset,
 205                             it->second.size() - frame_offset);
 206
 207     char* iov_ptr = static_cast<char*>(iov[iov_index].iov_base) + iov_offset;
 208     memcpy(iov_ptr,
 209            it->second.data() + frame_offset, bytes_to_read);
 210     frame_offset += bytes_to_read;
 211     iov_offset += bytes_to_read;
 212
 213     if (iov[iov_index].iov_len == iov_offset) {
 214       // We've filled this buffer.
 215       iov_offset = 0;
 216       ++iov_index;
 217     }
 218     if (it->second.size() == frame_offset) {
 219       // We've copied this whole frame
 220       RecordBytesConsumed(it->second.size());
 221       frames_.erase(it);
 222       it = frames_.begin();
 223       frame_offset = 0;
 224     }
 225   }
 226   // We've finished copying.  If we have a partial frame, update it.
 227   if (frame_offset != 0) {
 228     frames_.insert(make_pair(it->first + frame_offset,
 229                              it->second.substr(frame_offset)));
 230     frames_.erase(frames_.begin());
 231     RecordBytesConsumed(frame_offset);
 232   }
 233   return num_bytes_consumed_ - initial_bytes_consumed;
 234 }
 235
 236 bool QuicStreamSequencer::HasBytesToRead() const {
 237   FrameMap::const_iterator it = frames_.begin();
 238
 239   return it != frames_.end() && it->first == num_bytes_consumed_;
 240 }
 241
 242 bool QuicStreamSequencer::IsClosed() const {
 243   return num_bytes_consumed_ >= close_offset_;
 244 }
 245
 246 bool QuicStreamSequencer::IsDuplicate(const QuicStreamFrame& frame) const {
 247   // A frame is duplicate if the frame offset is smaller than our bytes consumed
 248   // or we have stored the frame in our map.
 249   // TODO(pwestin): Is it possible that a new frame contain more data even if
 250   // the offset is the same?
 251   return frame.offset < num_bytes_consumed_ ||
 252       frames_.find(frame.offset) != frames_.end();
 253 }
 254
 255 void QuicStreamSequencer::SetBlockedUntilFlush() {
 256   blocked_ = true;
 257 }
 258
 259 void QuicStreamSequencer::FlushBufferedFrames() {
 260   blocked_ = false;
 261   FrameMap::iterator it = frames_.find(num_bytes_consumed_);
 262   while (it != frames_.end()) {
 263     DVLOG(1) << "Flushing buffered packet at offset " << it->first;
 264     string* data = &it->second;
 265     size_t bytes_consumed = stream_->ProcessRawData(data->c_str(),
 266                                                     data->size());
 267     RecordBytesConsumed(bytes_consumed);
 268     if (MaybeCloseStream()) {
 269       return;
 270     }
 271     if (bytes_consumed > data->size()) {
 272       stream_->Reset(QUIC_ERROR_PROCESSING_STREAM);  // Programming error
 273       return;
 274     } else if (bytes_consumed == data->size()) {
 275       frames_.erase(it);
 276       it = frames_.find(num_bytes_consumed_);
 277     } else {
 278       string new_data = it->second.substr(bytes_consumed);
 279       frames_.erase(it);
 280       frames_.insert(make_pair(num_bytes_consumed_, new_data));
 281       return;
 282     }
 283   }
 284   MaybeCloseStream();
 285 }
 286
 287 void QuicStreamSequencer::RecordBytesConsumed(size_t bytes_consumed) {
 288   num_bytes_consumed_ += bytes_consumed;
 289   num_bytes_buffered_ -= bytes_consumed;
 290 }
 291
 292 }  // namespace net