rlz/lib/machine_id.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 "rlz/lib/machine_id.h"
   6
   7 #include "base/sha1.h"
   8 #include "rlz/lib/assert.h"
   9 #include "rlz/lib/crc8.h"
  10 #include "rlz/lib/string_utils.h"
  11
  12 namespace rlz_lib {
  13
  14 bool GetMachineId(std::string* machine_id) {
  15   if (!machine_id)
  16     return false;
  17
  18   static std::string calculated_id;
  19   static bool calculated = false;
  20   if (calculated) {
  21     *machine_id = calculated_id;
  22     return true;
  23   }
  24
  25   string16 sid_string;
  26   int volume_id;
  27   if (!GetRawMachineId(&sid_string, &volume_id))
  28     return false;
  29
  30   if (!testing::GetMachineIdImpl(sid_string, volume_id, machine_id))
  31     return false;
  32
  33   calculated = true;
  34   calculated_id = *machine_id;
  35   return true;
  36 }
  37
  38 namespace testing {
  39
  40 bool GetMachineIdImpl(const string16& sid_string,
  41                       int volume_id,
  42                       std::string* machine_id) {
  43   machine_id->clear();
  44
  45   // The ID should be the SID hash + the Hard Drive SNo. + checksum byte.
  46   static const int kSizeWithoutChecksum = base::kSHA1Length + sizeof(int);
  47   std::basic_string<unsigned char> id_binary(kSizeWithoutChecksum + 1, 0);
  48
  49   if (!sid_string.empty()) {
  50     // In order to be compatible with the old version of RLZ, the hash of the
  51     // SID must be done with all the original bytes from the unicode string.
  52     // However, the chromebase SHA1 hash function takes only an std::string as
  53     // input, so the unicode string needs to be converted to std::string
  54     // "as is".
  55     size_t byte_count = sid_string.size() * sizeof(string16::value_type);
  56     const char* buffer = reinterpret_cast<const char*>(sid_string.c_str());
  57     std::string sid_string_buffer(buffer, byte_count);
  58
  59     // Note that digest can have embedded nulls.
  60     std::string digest(base::SHA1HashString(sid_string_buffer));
  61     VERIFY(digest.size() == base::kSHA1Length);
  62     std::copy(digest.begin(), digest.end(), id_binary.begin());
  63   }
  64
  65   // Convert from int to binary (makes big-endian).
  66   for (size_t i = 0; i < sizeof(int); i++) {
  67     int shift_bits = 8 * (sizeof(int) - i - 1);
  68     id_binary[base::kSHA1Length + i] = static_cast<unsigned char>(
  69         (volume_id >> shift_bits) & 0xFF);
  70   }
  71
  72   // Append the checksum byte.
  73   if (!sid_string.empty() || (0 != volume_id))
  74     rlz_lib::Crc8::Generate(id_binary.c_str(),
  75                             kSizeWithoutChecksum,
  76                             &id_binary[kSizeWithoutChecksum]);
  77
  78   return rlz_lib::BytesToString(
  79       id_binary.c_str(), kSizeWithoutChecksum + 1, machine_id);
  80 }
  81
  82 }  // namespace testing
  83
  84 }  // namespace rlz_lib