net/quic/crypto/crypto_framer.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/crypto/crypto_framer.h"
   6
   7 #include "net/quic/crypto/crypto_protocol.h"
   8 #include "net/quic/quic_data_reader.h"
   9 #include "net/quic/quic_data_writer.h"
  10
  11 using base::StringPiece;
  12 using std::pair;
  13 using std::vector;
  14
  15 namespace net {
  16
  17 namespace {
  18
  19 const size_t kQuicTagSize = sizeof(uint32);
  20 const size_t kCryptoEndOffsetSize = sizeof(uint32);
  21 const size_t kNumEntriesSize = sizeof(uint16);
  22
  23 // OneShotVisitor is a framer visitor that records a single handshake message.
  24 class OneShotVisitor : public CryptoFramerVisitorInterface {
  25  public:
  26   OneShotVisitor() : error_(false) {}
  27
  28   void OnError(CryptoFramer* framer) override { error_ = true; }
  29
  30   void OnHandshakeMessage(const CryptoHandshakeMessage& message) override {
  31     out_.reset(new CryptoHandshakeMessage(message));
  32   }
  33
  34   bool error() const { return error_; }
  35
  36   CryptoHandshakeMessage* release() { return out_.release(); }
  37
  38  private:
  39   scoped_ptr<CryptoHandshakeMessage> out_;
  40   bool error_;
  41 };
  42
  43 }  // namespace
  44
  45 CryptoFramer::CryptoFramer()
  46     : visitor_(nullptr),
  47       num_entries_(0),
  48       values_len_(0) {
  49   Clear();
  50 }
  51
  52 CryptoFramer::~CryptoFramer() {}
  53
  54 // static
  55 CryptoHandshakeMessage* CryptoFramer::ParseMessage(StringPiece in) {
  56   OneShotVisitor visitor;
  57   CryptoFramer framer;
  58
  59   framer.set_visitor(&visitor);
  60   if (!framer.ProcessInput(in) || visitor.error() ||
  61       framer.InputBytesRemaining()) {
  62     return nullptr;
  63   }
  64
  65   return visitor.release();
  66 }
  67
  68 bool CryptoFramer::ProcessInput(StringPiece input) {
  69   DCHECK_EQ(QUIC_NO_ERROR, error_);
  70   if (error_ != QUIC_NO_ERROR) {
  71     return false;
  72   }
  73   error_ = Process(input);
  74   if (error_ != QUIC_NO_ERROR) {
  75     visitor_->OnError(this);
  76     return false;
  77   }
  78
  79   return true;
  80 }
  81
  82 // static
  83 QuicData* CryptoFramer::ConstructHandshakeMessage(
  84     const CryptoHandshakeMessage& message) {
  85   size_t num_entries = message.tag_value_map().size();
  86   size_t pad_length = 0;
  87   bool need_pad_tag = false;
  88   bool need_pad_value = false;
  89
  90   size_t len = message.size();
  91   if (len < message.minimum_size()) {
  92     need_pad_tag = true;
  93     need_pad_value = true;
  94     num_entries++;
  95
  96     size_t delta = message.minimum_size() - len;
  97     const size_t overhead = kQuicTagSize + kCryptoEndOffsetSize;
  98     if (delta > overhead) {
  99       pad_length = delta - overhead;
 100     }
 101     len += overhead + pad_length;
 102   }
 103
 104   if (num_entries > kMaxEntries) {
 105     return nullptr;
 106   }
 107
 108   scoped_ptr<char[]> buffer(new char[len]);
 109   QuicDataWriter writer(len, buffer.get());
 110   if (!writer.WriteUInt32(message.tag())) {
 111     DCHECK(false) << "Failed to write message tag.";
 112     return nullptr;
 113   }
 114   if (!writer.WriteUInt16(static_cast<uint16>(num_entries))) {
 115     DCHECK(false) << "Failed to write size.";
 116     return nullptr;
 117   }
 118   if (!writer.WriteUInt16(0)) {
 119     DCHECK(false) << "Failed to write padding.";
 120     return nullptr;
 121   }
 122
 123   uint32 end_offset = 0;
 124   // Tags and offsets
 125   for (QuicTagValueMap::const_iterator it = message.tag_value_map().begin();
 126        it != message.tag_value_map().end(); ++it) {
 127     if (it->first == kPAD && need_pad_tag) {
 128       // Existing PAD tags are only checked when padding needs to be added
 129       // because parts of the code may need to reserialize received messages
 130       // and those messages may, legitimately include padding.
 131       DCHECK(false) << "Message needed padding but already contained a PAD tag";
 132       return nullptr;
 133     }
 134
 135     if (it->first > kPAD && need_pad_tag) {
 136       need_pad_tag = false;
 137       if (!WritePadTag(&writer, pad_length, &end_offset)) {
 138         return nullptr;
 139       }
 140     }
 141
 142     if (!writer.WriteUInt32(it->first)) {
 143       DCHECK(false) << "Failed to write tag.";
 144       return nullptr;
 145     }
 146     end_offset += it->second.length();
 147     if (!writer.WriteUInt32(end_offset)) {
 148       DCHECK(false) << "Failed to write end offset.";
 149       return nullptr;
 150     }
 151   }
 152
 153   if (need_pad_tag) {
 154     if (!WritePadTag(&writer, pad_length, &end_offset)) {
 155       return nullptr;
 156     }
 157   }
 158
 159   // Values
 160   for (QuicTagValueMap::const_iterator it = message.tag_value_map().begin();
 161        it != message.tag_value_map().end(); ++it) {
 162     if (it->first > kPAD && need_pad_value) {
 163       need_pad_value = false;
 164       if (!writer.WriteRepeatedByte('-', pad_length)) {
 165         DCHECK(false) << "Failed to write padding.";
 166         return nullptr;
 167       }
 168     }
 169
 170     if (!writer.WriteBytes(it->second.data(), it->second.length())) {
 171       DCHECK(false) << "Failed to write value.";
 172       return nullptr;
 173     }
 174   }
 175
 176   if (need_pad_value) {
 177     if (!writer.WriteRepeatedByte('-', pad_length)) {
 178       DCHECK(false) << "Failed to write padding.";
 179       return nullptr;
 180     }
 181   }
 182
 183   return new QuicData(buffer.release(), len, true);
 184 }
 185
 186 void CryptoFramer::Clear() {
 187   message_.Clear();
 188   tags_and_lengths_.clear();
 189   error_ = QUIC_NO_ERROR;
 190   state_ = STATE_READING_TAG;
 191 }
 192
 193 QuicErrorCode CryptoFramer::Process(StringPiece input) {
 194   // Add this data to the buffer.
 195   buffer_.append(input.data(), input.length());
 196   QuicDataReader reader(buffer_.data(), buffer_.length());
 197
 198   switch (state_) {
 199     case STATE_READING_TAG:
 200       if (reader.BytesRemaining() < kQuicTagSize) {
 201         break;
 202       }
 203       QuicTag message_tag;
 204       reader.ReadUInt32(&message_tag);
 205       message_.set_tag(message_tag);
 206       state_ = STATE_READING_NUM_ENTRIES;
 207     case STATE_READING_NUM_ENTRIES:
 208       if (reader.BytesRemaining() < kNumEntriesSize + sizeof(uint16)) {
 209         break;
 210       }
 211       reader.ReadUInt16(&num_entries_);
 212       if (num_entries_ > kMaxEntries) {
 213         return QUIC_CRYPTO_TOO_MANY_ENTRIES;
 214       }
 215       uint16 padding;
 216       reader.ReadUInt16(&padding);
 217
 218       tags_and_lengths_.reserve(num_entries_);
 219       state_ = STATE_READING_TAGS_AND_LENGTHS;
 220       values_len_ = 0;
 221     case STATE_READING_TAGS_AND_LENGTHS: {
 222       if (reader.BytesRemaining() <
 223               num_entries_ * (kQuicTagSize + kCryptoEndOffsetSize)) {
 224         break;
 225       }
 226
 227       uint32 last_end_offset = 0;
 228       for (unsigned i = 0; i < num_entries_; ++i) {
 229         QuicTag tag;
 230         reader.ReadUInt32(&tag);
 231         if (i > 0 && tag <= tags_and_lengths_[i-1].first) {
 232           if (tag == tags_and_lengths_[i-1].first) {
 233             return QUIC_CRYPTO_DUPLICATE_TAG;
 234           }
 235           return QUIC_CRYPTO_TAGS_OUT_OF_ORDER;
 236         }
 237
 238         uint32 end_offset;
 239         reader.ReadUInt32(&end_offset);
 240
 241         if (end_offset < last_end_offset) {
 242           return QUIC_CRYPTO_TAGS_OUT_OF_ORDER;
 243         }
 244         tags_and_lengths_.push_back(std::make_pair(
 245             tag, static_cast<size_t>(end_offset - last_end_offset)));
 246         last_end_offset = end_offset;
 247       }
 248       values_len_ = last_end_offset;
 249       state_ = STATE_READING_VALUES;
 250     }
 251     case STATE_READING_VALUES:
 252       if (reader.BytesRemaining() < values_len_) {
 253         break;
 254       }
 255       for (vector<pair<QuicTag, size_t> >::const_iterator
 256            it = tags_and_lengths_.begin(); it != tags_and_lengths_.end();
 257            it++) {
 258         StringPiece value;
 259         reader.ReadStringPiece(&value, it->second);
 260         message_.SetStringPiece(it->first, value);
 261       }
 262       visitor_->OnHandshakeMessage(message_);
 263       Clear();
 264       state_ = STATE_READING_TAG;
 265       break;
 266   }
 267   // Save any remaining data.
 268   buffer_ = reader.PeekRemainingPayload().as_string();
 269   return QUIC_NO_ERROR;
 270 }
 271
 272 // static
 273 bool CryptoFramer::WritePadTag(QuicDataWriter* writer,
 274                                size_t pad_length,
 275                                uint32* end_offset) {
 276   if (!writer->WriteUInt32(kPAD)) {
 277     DCHECK(false) << "Failed to write tag.";
 278     return false;
 279   }
 280   *end_offset += pad_length;
 281   if (!writer->WriteUInt32(*end_offset)) {
 282     DCHECK(false) << "Failed to write end offset.";
 283     return false;
 284   }
 285   return true;
 286 }
 287
 288 }  // namespace net