(Second attempt at http://codereview.chromium.org/553069/show)...

chrome/browser/geolocation/wifi_data_provider_win.cc

+// Copyright 2008, Google Inc.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are met:
+//
+//  1. Redistributions of source code must retain the above copyright notice,
+//     this list of conditions and the following disclaimer.
+//  2. Redistributions in binary form must reproduce the above copyright notice,
+//     this list of conditions and the following disclaimer in the documentation
+//     and/or other materials provided with the distribution.
+//  3. Neither the name of Google Inc. nor the names of its contributors may be
+//     used to endorse or promote products derived from this software without
+//     specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
+// WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO
+// EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+// OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+// OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+// ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Windows Vista uses the Native Wifi (WLAN) API for accessing WiFi cards. See
+// http://msdn.microsoft.com/en-us/library/ms705945(VS.85).aspx. Windows XP
+// Service Pack 3 (and Windows XP Service Pack 2, if upgraded with a hot fix)
+// also support a limited version of the WLAN API. See
+// http://msdn.microsoft.com/en-us/library/bb204766.aspx. The WLAN API uses
+// wlanapi.h, which is not part of the SDK used by Gears, so is replicated
+// locally using data from the MSDN.
+//
+// Windows XP from Service Pack 2 onwards supports the Wireless Zero
+// Configuration (WZC) programming interface. See
+// http://msdn.microsoft.com/en-us/library/ms706587(VS.85).aspx. 
+//
+// The MSDN recommends that one use the WLAN API where available, and WZC
+// otherwise.
+//
+// However, it seems that WZC fails for some wireless cards. Also, WLAN seems
+// not to work on XP SP3. So we use WLAN on Vista, and use NDIS directly
+// otherwise.
+
+// TODO(cprince): remove platform-specific #ifdef guards when OS-specific
+// sources (e.g. WIN32_CPPSRCS) are implemented
+#if defined(WIN32) && !defined(OS_WINCE)
+
+#include "gears/geolocation/wifi_data_provider_win32.h"
+
+#include <windows.h>
+#include <ntddndis.h>  // For IOCTL_NDIS_QUERY_GLOBAL_STATS
+#include "gears/base/common/string_utils.h"
+#include "gears/base/common/vista_utils.h"
+#include "gears/geolocation/wifi_data_provider_common.h"
+#include "gears/geolocation/wifi_data_provider_windows_common.h"
+
+// Taken from ndis.h for WinCE.
+#define NDIS_STATUS_INVALID_LENGTH   ((NDIS_STATUS)0xC0010014L)
+#define NDIS_STATUS_BUFFER_TOO_SHORT ((NDIS_STATUS)0xC0010016L)
+
+// The limits on the size of the buffer used for the OID query.
+static const int kInitialBufferSize = 2 << 12;  // Good for about 50 APs.
+static const int kMaximumBufferSize = 2 << 20;  // 2MB
+
+// Length for generic string buffers passed to Win32 APIs.
+static const int kStringLength = 512;
+
+// The time periods, in milliseconds, between successive polls of the wifi data.
+extern const int kDefaultPollingInterval = 10000;  // 10s
+extern const int kNoChangePollingInterval = 120000;  // 2 mins
+extern const int kTwoNoChangePollingInterval = 600000;  // 10 mins
+
+// Local functions
+
+// Extracts data for an access point and converts to Gears format.
+static bool GetNetworkData(const WLAN_BSS_ENTRY &bss_entry,
+                           AccessPointData *access_point_data);
+bool UndefineDosDevice(const std::string16 &device_name);
+bool DefineDosDeviceIfNotExists(const std::string16 &device_name);
+HANDLE GetFileHandle(const std::string16 &device_name);
+// Makes the OID query and returns a Win32 error code.
+int PerformQuery(HANDLE adapter_handle,
+                 BYTE *buffer,
+                 DWORD buffer_size,
+                 DWORD *bytes_out);
+bool ResizeBuffer(int requested_size, BYTE **buffer);
+// Gets the system directory and appends a trailing slash if not already
+// present.
+bool GetSystemDirectory(std::string16 *path);
+
+// static
+template<>
+WifiDataProviderImplBase *WifiDataProvider::DefaultFactoryFunction() {
+  return new Win32WifiDataProvider();
+}
+
+
+Win32WifiDataProvider::Win32WifiDataProvider()
+    : oid_buffer_size_(kInitialBufferSize),
+      is_first_scan_complete_(false) {
+  // Start the polling thread.
+  Start();
+}
+
+Win32WifiDataProvider::~Win32WifiDataProvider() {
+  stop_event_.Signal();
+  Join();
+}
+
+bool Win32WifiDataProvider::GetData(WifiData *data) {
+  assert(data);
+  MutexLock lock(&data_mutex_);
+  *data = wifi_data_;
+  // If we've successfully completed a scan, indicate that we have all of the
+  // data we can get.
+  return is_first_scan_complete_;
+}
+
+// Thread implementation
+void Win32WifiDataProvider::Run() {
+  // We use an absolute path to load the DLL to avoid DLL preloading attacks.
+  HINSTANCE library = NULL;
+  std::string16 system_directory;
+  if (GetSystemDirectory(&system_directory)) {
+    assert(!system_directory.empty());
+    std::string16 dll_path = system_directory + L"wlanapi.dll";
+    library = LoadLibraryEx(dll_path.c_str(),
+                            NULL,
+                            LOAD_WITH_ALTERED_SEARCH_PATH);
+  }
+
+  // Use the WLAN interface if we're on Vista and if it's available. Otherwise,
+  // use NDIS.
+  typedef bool (Win32WifiDataProvider::*GetAccessPointDataFunction)(
+      WifiData::AccessPointDataSet *data);
+  GetAccessPointDataFunction get_access_point_data_function = NULL;
+  if (VistaUtils::IsRunningOnVista() && library) {
+    GetWLANFunctions(library);
+    get_access_point_data_function =
+        &Win32WifiDataProvider::GetAccessPointDataWLAN;
+  } else {
+    // We assume the list of interfaces doesn't change while Gears is running.
+    if (!GetInterfacesNDIS()) {
+      is_first_scan_complete_ = true;
+      return;
+    }
+    get_access_point_data_function =
+        &Win32WifiDataProvider::GetAccessPointDataNDIS;
+  }
+  assert(get_access_point_data_function);
+
+  int polling_interval = kDefaultPollingInterval;
+  // Regularly get the access point data.
+  do {
+    WifiData new_data;
+    if ((this->*get_access_point_data_function)(&new_data.access_point_data)) {
+      bool update_available;
+      data_mutex_.Lock();
+      update_available = wifi_data_.DiffersSignificantly(new_data);
+      wifi_data_ = new_data;
+      data_mutex_.Unlock();
+      polling_interval =
+          UpdatePollingInterval(polling_interval, update_available);
+      if (update_available) {
+        is_first_scan_complete_ = true;
+        NotifyListeners();
+      }
+    }
+  } while (!stop_event_.WaitWithTimeout(polling_interval));
+
+  FreeLibrary(library);
+}
+
+// WLAN functions
+
+void Win32WifiDataProvider::GetWLANFunctions(HINSTANCE wlan_library) {
+  assert(wlan_library);
+  WlanOpenHandle_function_ = reinterpret_cast<WlanOpenHandleFunction>(
+      GetProcAddress(wlan_library, "WlanOpenHandle"));
+  WlanEnumInterfaces_function_ = reinterpret_cast<WlanEnumInterfacesFunction>(
+      GetProcAddress(wlan_library, "WlanEnumInterfaces"));
+  WlanGetNetworkBssList_function_ =
+      reinterpret_cast<WlanGetNetworkBssListFunction>(
+      GetProcAddress(wlan_library, "WlanGetNetworkBssList"));
+  WlanFreeMemory_function_ = reinterpret_cast<WlanFreeMemoryFunction>(
+      GetProcAddress(wlan_library, "WlanFreeMemory"));
+  WlanCloseHandle_function_ = reinterpret_cast<WlanCloseHandleFunction>(
+      GetProcAddress(wlan_library, "WlanCloseHandle"));
+  assert(WlanOpenHandle_function_ &&
+         WlanEnumInterfaces_function_ &&
+         WlanGetNetworkBssList_function_ &&
+         WlanFreeMemory_function_ &&
+         WlanCloseHandle_function_);
+}
+
+bool Win32WifiDataProvider::GetAccessPointDataWLAN(
+    WifiData::AccessPointDataSet *data) {
+  assert(data);
+
+  // Get the handle to the WLAN API.
+  DWORD negotiated_version;
+  HANDLE wlan_handle = NULL;
+  // We could be executing on either Windows XP or Windows Vista, so use the
+  // lower version of the client WLAN API. It seems that the negotiated version
+  // is the Vista version irrespective of what we pass!
+  static const int kXpWlanClientVersion = 1;
+  if ((*WlanOpenHandle_function_)(kXpWlanClientVersion,
+                                  NULL,
+                                  &negotiated_version,
+                                  &wlan_handle) != ERROR_SUCCESS) {
+    return false;
+  }
+  assert(wlan_handle);
+
+  // Get the list of interfaces. WlanEnumInterfaces allocates interface_list.
+  WLAN_INTERFACE_INFO_LIST *interface_list = NULL;
+  if ((*WlanEnumInterfaces_function_)(wlan_handle, NULL, &interface_list) !=
+      ERROR_SUCCESS) {
+    return false;
+  }
+  assert(interface_list);
+
+  // Go through the list of interfaces and get the data for each.
+  for (int i = 0; i < static_cast<int>(interface_list->dwNumberOfItems); ++i) {
+    GetInterfaceDataWLAN(wlan_handle,
+                         interface_list->InterfaceInfo[i].InterfaceGuid,
+                         data);
+  }
+
+  // Free interface_list.
+  (*WlanFreeMemory_function_)(interface_list);
+
+  // Close the handle.
+  if ((*WlanCloseHandle_function_)(wlan_handle, NULL) != ERROR_SUCCESS) {
+    return false;
+  }
+
+  return true;
+}
+
+// Appends the data for a single interface to the data vector. Returns the
+// number of access points found, or -1 on error.
+int Win32WifiDataProvider::GetInterfaceDataWLAN(
+    const HANDLE wlan_handle,
+    const GUID &interface_id,
+    WifiData::AccessPointDataSet *data) {
+  assert(data);
+  // WlanGetNetworkBssList allocates bss_list.
+  WLAN_BSS_LIST *bss_list;
+  if ((*WlanGetNetworkBssList_function_)(wlan_handle,
+                                         &interface_id,
+                                         NULL,   // Use all SSIDs.
+                                         DOT11_BSS_TYPE_UNUSED,
+                                         false,  // bSecurityEnabled - unused
+                                         NULL,   // reserved
+                                         &bss_list) != ERROR_SUCCESS) {
+    return -1;
+  }
+
+  int found = 0;
+  for (int i = 0; i < static_cast<int>(bss_list->dwNumberOfItems); ++i) {
+    AccessPointData access_point_data;
+    if (GetNetworkData(bss_list->wlanBssEntries[i], &access_point_data)) {
+      ++found;
+      data->insert(access_point_data);
+    }
+  }
+
+  (*WlanFreeMemory_function_)(bss_list);
+
+  return found;
+}
+
+// NDIS functions
+
+bool Win32WifiDataProvider::GetInterfacesNDIS() {
+  HKEY network_cards_key = NULL;
+  if (RegOpenKeyEx(
+      HKEY_LOCAL_MACHINE,
+      L"Software\\Microsoft\\Windows NT\\CurrentVersion\\NetworkCards",
+      0,
+      KEY_READ,
+      &network_cards_key) != ERROR_SUCCESS) {
+    return false;
+  }
+  assert(network_cards_key);
+
+  for (int i = 0; ; ++i) {
+    TCHAR name[kStringLength];
+    DWORD name_size = kStringLength;
+    FILETIME time;
+    if (RegEnumKeyEx(network_cards_key,
+                     i,
+                     name,
+                     &name_size,
+                     NULL,
+                     NULL,
+                     NULL,
+                     &time) != ERROR_SUCCESS) {
+      break;
+    }
+    HKEY hardware_key = NULL;
+    if (RegOpenKeyEx(network_cards_key, name, 0, KEY_READ, &hardware_key) !=
+        ERROR_SUCCESS) {
+      break;
+    }
+    assert(hardware_key);
+
+    TCHAR service_name[kStringLength];
+    DWORD service_name_size = kStringLength;
+    DWORD type = 0;
+    if (RegQueryValueEx(hardware_key,
+                        L"ServiceName",
+                        NULL,
+                        &type,
+                        reinterpret_cast<LPBYTE>(service_name),
+                        &service_name_size) == ERROR_SUCCESS) {
+      interface_service_names_.push_back(service_name);
+    }
+    RegCloseKey(hardware_key);
+  }
+
+  RegCloseKey(network_cards_key);
+  return true;
+}
+
+bool Win32WifiDataProvider::GetAccessPointDataNDIS(
+    WifiData::AccessPointDataSet *data) {
+  assert(data);
+
+  for (int i = 0; i < static_cast<int>(interface_service_names_.size()); ++i) {
+    // First, check that we have a DOS device for this adapter.
+    if (!DefineDosDeviceIfNotExists(interface_service_names_[i])) {
+      continue;
+    }
+
+    // Get the handle to the device. This will fail if the named device is not
+    // valid.
+    HANDLE adapter_handle = GetFileHandle(interface_service_names_[i]);
+    if (adapter_handle == INVALID_HANDLE_VALUE) {
+      continue;
+    }
+
+    // Get the data.
+    GetInterfaceDataNDIS(adapter_handle, data);
+
+    // Clean up.
+    CloseHandle(adapter_handle);
+    UndefineDosDevice(interface_service_names_[i]);
+  }
+
+  return true;
+}
+
+bool Win32WifiDataProvider::GetInterfaceDataNDIS(
+    HANDLE adapter_handle,
+    WifiData::AccessPointDataSet *data) {
+  assert(data);
+
+  BYTE *buffer = reinterpret_cast<BYTE*>(malloc(oid_buffer_size_));
+  if (buffer == NULL) {
+    return false;
+  }
+
+  DWORD bytes_out;
+  int result;
+
+  while (true) {
+    bytes_out = 0;
+    result = PerformQuery(adapter_handle, buffer, oid_buffer_size_, &bytes_out);
+    if (result == ERROR_GEN_FAILURE ||  // Returned by some Intel cards.
+        result == ERROR_INSUFFICIENT_BUFFER ||
+        result == ERROR_MORE_DATA ||
+        result == NDIS_STATUS_INVALID_LENGTH ||
+        result == NDIS_STATUS_BUFFER_TOO_SHORT) {
+      // The buffer we supplied is too small, so increase it. bytes_out should
+      // provide the required buffer size, but this is not always the case.
+      if (bytes_out > static_cast<DWORD>(oid_buffer_size_)) {
+        oid_buffer_size_ = bytes_out;
+      } else {
+        oid_buffer_size_ *= 2;
+      }
+      if (!ResizeBuffer(oid_buffer_size_, &buffer)) {
+        oid_buffer_size_ = kInitialBufferSize;  // Reset for next time.
+        return false;
+      }
+    } else {
+      // The buffer is not too small.
+      break;
+    }
+  }
+  assert(buffer);
+
+  if (result == ERROR_SUCCESS) {
+    NDIS_802_11_BSSID_LIST* bssid_list =
+        reinterpret_cast<NDIS_802_11_BSSID_LIST*>(buffer);
+    GetDataFromBssIdList(*bssid_list, oid_buffer_size_, data);
+  }
+
+  free(buffer);
+  return true;
+}
+
+// Local functions
+
+static bool GetNetworkData(const WLAN_BSS_ENTRY &bss_entry,
+                           AccessPointData *access_point_data) {
+  // Currently we get only MAC address, signal strength and SSID.
+  assert(access_point_data);
+  access_point_data->mac_address = MacAddressAsString16(bss_entry.dot11Bssid);
+  access_point_data->radio_signal_strength = bss_entry.lRssi;
+  // bss_entry.dot11Ssid.ucSSID is not null-terminated.
+  UTF8ToString16(reinterpret_cast<const char*>(bss_entry.dot11Ssid.ucSSID),
+                 static_cast<ULONG>(bss_entry.dot11Ssid.uSSIDLength),
+                 &access_point_data->ssid);
+  // TODO(steveblock): Is it possible to get the following?
+  //access_point_data->signal_to_noise
+  //access_point_data->age
+  //access_point_data->channel
+  return true;
+}
+
+bool UndefineDosDevice(const std::string16 &device_name) {
+  // We remove only the mapping we use, that is \Device\<device_name>.
+  std::string16 target_path = L"\\Device\\" + device_name;
+  return DefineDosDevice(
+      DDD_RAW_TARGET_PATH | DDD_REMOVE_DEFINITION | DDD_EXACT_MATCH_ON_REMOVE,
+      device_name.c_str(),
+      target_path.c_str()) == TRUE;
+}
+
+bool DefineDosDeviceIfNotExists(const std::string16 &device_name) {
+  // We create a DOS device name for the device at \Device\<device_name>.
+  std::string16 target_path = L"\\Device\\" + device_name;
+
+  TCHAR target[kStringLength];
+  if (QueryDosDevice(device_name.c_str(), target, kStringLength) > 0 &&
+      target_path.compare(target) == 0) {
+    // Device already exists.
+    return true;
+  }
+
+  if (GetLastError() != ERROR_FILE_NOT_FOUND) {
+    return false;
+  }
+
+  if (!DefineDosDevice(DDD_RAW_TARGET_PATH,
+                       device_name.c_str(),
+                       target_path.c_str())) {
+    return false;
+  }
+
+  // Check that the device is really there.
+  return QueryDosDevice(device_name.c_str(), target, kStringLength) > 0 &&
+      target_path.compare(target) == 0;
+}
+
+HANDLE GetFileHandle(const std::string16 &device_name) {
+  // We access a device with DOS path \Device\<device_name> at
+  // \\.\<device_name>.
+  std::string16 formatted_device_name = L"\\\\.\\" + device_name;
+
+  return CreateFile(formatted_device_name.c_str(),
+                    GENERIC_READ,
+                    FILE_SHARE_READ | FILE_SHARE_WRITE,  // share mode
+                    0,  // security attributes
+                    OPEN_EXISTING,
+                    0,  // flags and attributes
+                    INVALID_HANDLE_VALUE);
+}
+
+int PerformQuery(HANDLE adapter_handle,
+                 BYTE *buffer,
+                 DWORD buffer_size,
+                 DWORD *bytes_out) {
+  DWORD oid = OID_802_11_BSSID_LIST;
+  if (!DeviceIoControl(adapter_handle,
+                       IOCTL_NDIS_QUERY_GLOBAL_STATS,
+                       &oid,
+                       sizeof(oid),
+                       buffer,
+                       buffer_size,
+                       bytes_out,
+                       NULL)) {
+    return GetLastError();
+  }
+  return ERROR_SUCCESS;
+}
+
+bool ResizeBuffer(int requested_size, BYTE **buffer) {
+  if (requested_size > kMaximumBufferSize) {
+    free(*buffer);
+    *buffer = NULL;
+    return false;
+  }
+
+  BYTE *new_buffer = reinterpret_cast<BYTE*>(realloc(*buffer, requested_size));
+  if (new_buffer == NULL) {
+    free(*buffer);
+    *buffer = NULL;
+    return false;
+  }
+
+  *buffer = new_buffer;
+  return true;
+}
+
+bool GetSystemDirectory(std::string16 *path) {
+  assert(path);
+  // Return value includes terminating NULL.
+  int buffer_size = GetSystemDirectory(NULL, 0);
+  if (buffer_size == 0) {
+    return false;
+  }
+  char16 *buffer = new char16[buffer_size];
+
+  // Return value excludes terminating NULL.
+  int characters_written = GetSystemDirectory(buffer, buffer_size);
+  if (characters_written == 0) {
+    return false;
+  }
+  assert(characters_written == buffer_size - 1);
+
+  path->assign(buffer);
+  delete[] buffer;
+
+  if (path->at(path->length() - 1) != L'\\') {
+    path->append(L"\\");
+  }
+  return true;
+}
+
+#endif  // WIN32 && !OS_WINCE