components/user_prefs/tracked/device_id_win.cc

   1 // Copyright 2015 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 "components/user_prefs/tracked/device_id.h"
   6
   7 #include <windows.h>
   8 #include <sddl.h>  // For ConvertSidToStringSidA.
   9
  10 #include "base/logging.h"
  11 #include "base/macros.h"
  12 #include "base/memory/scoped_ptr.h"
  13
  14 MachineIdStatus GetDeterministicMachineSpecificId(std::string* machine_id) {
  15   DCHECK(machine_id);
  16
  17   wchar_t computer_name[MAX_COMPUTERNAME_LENGTH + 1] = {};
  18   DWORD computer_name_size = arraysize(computer_name);
  19
  20   if (!::GetComputerNameW(computer_name, &computer_name_size))
  21     return MachineIdStatus::FAILURE;
  22
  23   DWORD sid_size = SECURITY_MAX_SID_SIZE;
  24   char sid_buffer[SECURITY_MAX_SID_SIZE];
  25   SID* sid = reinterpret_cast<SID*>(sid_buffer);
  26   DWORD domain_size = 128;  // Will expand below if needed.
  27   scoped_ptr<wchar_t[]> domain_buffer(new wchar_t[domain_size]);
  28   SID_NAME_USE sid_name_use;
  29
  30   // Although the fifth argument to |LookupAccountNameW()|,
  31   // |ReferencedDomainName|, is annotated as |_Out_opt_|, if a null
  32   // value is passed in, zero is returned and |GetLastError()| will
  33   // return |ERROR_INSUFFICIENT_BUFFER| (assuming that nothing else went
  34   // wrong). In order to ensure that the call to |LookupAccountNameW()|
  35   // has succeeded, it is necessary to include the following logic and
  36   // obtain the domain name.
  37   if (!::LookupAccountNameW(nullptr, computer_name, sid, &sid_size,
  38                             domain_buffer.get(), &domain_size, &sid_name_use)) {
  39     // If the initial size of |domain_buffer| was too small, the
  40     // required size is now found in |domain_size|. Resize and try
  41     // again.
  42     if (::GetLastError() != ERROR_INSUFFICIENT_BUFFER)
  43       return MachineIdStatus::FAILURE;
  44
  45     domain_buffer.reset(new wchar_t[domain_size]);
  46     if (!::LookupAccountNameW(nullptr, computer_name, sid, &sid_size,
  47                               domain_buffer.get(), &domain_size,
  48                               &sid_name_use)) {
  49       return MachineIdStatus::FAILURE;
  50     }
  51   }
  52
  53   // Ensure that the correct type of SID was obtained. The
  54   // |LookupAccountNameW()| function seems to always return
  55   // |SidTypeDomain| instead of |SidTypeComputer| when the computer name
  56   // is passed in as its second argument and therefore both enum values
  57   // will be considered acceptable. If the computer name and user name
  58   // coincide, |LookupAccountNameW()| seems to always return the machine
  59   // SID and set the returned enum to |SidTypeDomain|.
  60   DCHECK(sid_name_use == SID_NAME_USE::SidTypeComputer ||
  61          sid_name_use == SID_NAME_USE::SidTypeDomain);
  62
  63   char* sid_string = nullptr;
  64   if (!::ConvertSidToStringSidA(sid, &sid_string))
  65     return MachineIdStatus::FAILURE;
  66
  67   *machine_id = sid_string;
  68   ::LocalFree(sid_string);
  69
  70   return MachineIdStatus::SUCCESS;
  71 }