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 <stdint.h>
   6
   7 #include "net/quic/crypto/null_decrypter.h"
   8 #include "net/quic/quic_utils.h"
   9 #include "net/quic/quic_data_reader.h"
  10
  11 using base::StringPiece;
  12 using std::string;
  13
  14 namespace net {
  15
  16 NullDecrypter::NullDecrypter() {}
  17
  18 bool NullDecrypter::SetKey(StringPiece key) { return key.empty(); }
  19
  20 bool NullDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
  21   return nonce_prefix.empty();
  22 }
  23
  24 bool NullDecrypter::DecryptPacket(QuicPacketSequenceNumber /*seq_number*/,
  25                                   const StringPiece& associated_data,
  26                                   const StringPiece& ciphertext,
  27                                   char* output,
  28                                   size_t* output_length,
  29                                   size_t max_output_length) {
  30   QuicDataReader reader(ciphertext.data(), ciphertext.length());
  31   uint128 hash;
  32
  33   if (!ReadHash(&reader, &hash)) {
  34     return false;
  35   }
  36
  37   StringPiece plaintext = reader.ReadRemainingPayload();
  38   if (plaintext.length() > max_output_length) {
  39     LOG(DFATAL) << "Output buffer must be larger than the plaintext.";
  40     return false;
  41   }
  42   if (hash != ComputeHash(associated_data, plaintext)) {
  43     return false;
  44   }
  45   // Copy the plaintext to output.
  46   memcpy(output, plaintext.data(), plaintext.length());
  47   *output_length = plaintext.length();
  48   return true;
  49 }
  50
  51 StringPiece NullDecrypter::GetKey() const { return StringPiece(); }
  52
  53 StringPiece NullDecrypter::GetNoncePrefix() const { return StringPiece(); }
  54
  55 bool NullDecrypter::ReadHash(QuicDataReader* reader, uint128* hash) {
  56   uint64 lo;
  57   uint32 hi;
  58   if (!reader->ReadUInt64(&lo) ||
  59       !reader->ReadUInt32(&hi)) {
  60     return false;
  61   }
  62   *hash = hi;
  63   *hash <<= 64;
  64   *hash += lo;
  65   return true;
  66 }
  67
  68 uint128 NullDecrypter::ComputeHash(const StringPiece& data1,
  69                                    const StringPiece& data2) const {
  70   uint128 correct_hash = QuicUtils::FNV1a_128_Hash_Two(
  71       data1.data(), data1.length(), data2.data(), data2.length());
  72   uint128 mask(UINT64_C(0x0), UINT64_C(0xffffffff));
  73   mask <<= 96;
  74   correct_hash &= ~mask;
  75   return correct_hash;
  76 }
  77
  78 }  // namespace net