net/quic/crypto/null_decrypter.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/null_decrypter.h"
   6 #include "net/quic/quic_utils.h"
   7 #include "net/quic/quic_data_reader.h"
   8
   9 using base::StringPiece;
  10 using std::string;
  11
  12 namespace net {
  13
  14 NullDecrypter::NullDecrypter() {}
  15
  16 bool NullDecrypter::SetKey(StringPiece key) { return key.empty(); }
  17
  18 bool NullDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
  19   return nonce_prefix.empty();
  20 }
  21
  22 bool NullDecrypter::DecryptPacket(QuicPacketSequenceNumber /*seq_number*/,
  23                                   const StringPiece& associated_data,
  24                                   const StringPiece& ciphertext,
  25                                   char* output,
  26                                   size_t* output_length,
  27                                   size_t max_output_length) {
  28   QuicDataReader reader(ciphertext.data(), ciphertext.length());
  29   uint128 hash;
  30
  31   if (!ReadHash(&reader, &hash)) {
  32     return false;
  33   }
  34
  35   StringPiece plaintext = reader.ReadRemainingPayload();
  36   if (plaintext.length() > max_output_length) {
  37     LOG(DFATAL) << "Output buffer must be larger than the plaintext.";
  38     return false;
  39   }
  40   if (hash != ComputeHash(associated_data, plaintext)) {
  41     return false;
  42   }
  43   // Copy the plaintext to output.
  44   memcpy(output, plaintext.data(), plaintext.length());
  45   *output_length = plaintext.length();
  46   return true;
  47 }
  48
  49 StringPiece NullDecrypter::GetKey() const { return StringPiece(); }
  50
  51 StringPiece NullDecrypter::GetNoncePrefix() const { return StringPiece(); }
  52
  53 bool NullDecrypter::ReadHash(QuicDataReader* reader, uint128* hash) {
  54   uint64 lo;
  55   uint32 hi;
  56   if (!reader->ReadUInt64(&lo) ||
  57       !reader->ReadUInt32(&hi)) {
  58     return false;
  59   }
  60   *hash = hi;
  61   *hash <<= 64;
  62   *hash += lo;
  63   return true;
  64 }
  65
  66 uint128 NullDecrypter::ComputeHash(const StringPiece& data1,
  67                                    const StringPiece& data2) const {
  68   uint128 correct_hash = QuicUtils::FNV1a_128_Hash_Two(
  69       data1.data(), data1.length(), data2.data(), data2.length());
  70   uint128 mask(GG_UINT64_C(0x0), GG_UINT64_C(0xffffffff));
  71   mask <<= 96;
  72   correct_hash &= ~mask;
  73   return correct_hash;
  74 }
  75
  76 }  // namespace net