Cast: Allow extension to control wifi options on windows

net/base/net_util_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/base/net_util.h"
 
 #include <iphlpapi.h>
 #include <wlanapi.h>
 
 #include <algorithm>
 
 #include "base/files/file_path.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/threading/thread_restrictions.h"
 #include "base/win/scoped_handle.h"
 #include "base/win/windows_version.h"
 #include "net/base/escape.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
+#include "net/base/net_util_win.h"
 #include "url/gurl.h"
 
 namespace net {
 
 namespace {
 
-struct WlanApi {
-  typedef DWORD (WINAPI *WlanOpenHandleFunc)(
-      DWORD, VOID*, DWORD*, HANDLE*);
-  typedef DWORD (WINAPI *WlanEnumInterfacesFunc)(
-      HANDLE, VOID*, WLAN_INTERFACE_INFO_LIST**);
-  typedef DWORD (WINAPI *WlanQueryInterfaceFunc)(
-      HANDLE, const GUID*, WLAN_INTF_OPCODE, VOID*, DWORD*, VOID**,
-      WLAN_OPCODE_VALUE_TYPE*);
-  typedef VOID (WINAPI *WlanFreeMemoryFunc)(VOID*);
-  typedef DWORD (WINAPI *WlanCloseHandleFunc)(HANDLE, VOID*);
-
-  WlanApi() : initialized(false) {
-    // Use an absolute path to load the DLL to avoid DLL preloading attacks.
-    static const wchar_t* const kDLL = L"%WINDIR%\\system32\\wlanapi.dll";
-    wchar_t path[MAX_PATH] = {0};
-    ExpandEnvironmentStrings(kDLL, path, arraysize(path));
-    module = ::LoadLibraryEx(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
-    if (!module)
-      return;
-
-    open_handle_func = reinterpret_cast<WlanOpenHandleFunc>(
-        ::GetProcAddress(module, "WlanOpenHandle"));
-    enum_interfaces_func = reinterpret_cast<WlanEnumInterfacesFunc>(
-        ::GetProcAddress(module, "WlanEnumInterfaces"));
-    query_interface_func = reinterpret_cast<WlanQueryInterfaceFunc>(
-        ::GetProcAddress(module, "WlanQueryInterface"));
-    free_memory_func = reinterpret_cast<WlanFreeMemoryFunc>(
-        ::GetProcAddress(module, "WlanFreeMemory"));
-    close_handle_func = reinterpret_cast<WlanCloseHandleFunc>(
-        ::GetProcAddress(module, "WlanCloseHandle"));
-    initialized = open_handle_func && enum_interfaces_func &&
-                  query_interface_func && free_memory_func &&
-                  close_handle_func;
-  }
-
-  template <typename T>
-  DWORD OpenHandle(DWORD client_version, DWORD* cur_version, T* handle) const {
-    HANDLE temp_handle;
-    DWORD result = open_handle_func(client_version, NULL, cur_version,
-                                    &temp_handle);
-    if (result != ERROR_SUCCESS)
-      return result;
-    handle->Set(temp_handle);
-    return ERROR_SUCCESS;
-  }
-
-  HMODULE module;
-  WlanOpenHandleFunc open_handle_func;
-  WlanEnumInterfacesFunc enum_interfaces_func;
-  WlanQueryInterfaceFunc query_interface_func;
-  WlanFreeMemoryFunc free_memory_func;
-  WlanCloseHandleFunc close_handle_func;
-  bool initialized;
-};
-
 // Converts Windows defined types to NetworkInterfaceType.
 NetworkChangeNotifier::ConnectionType GetNetworkInterfaceType(DWORD ifType) {
   // Bail out for pre-Vista versions of Windows which are documented to give
   // inaccurate results like returning Ethernet for WiFi.
   // http://msdn.microsoft.com/en-us/library/windows/desktop/aa366058.aspx
   if (base::win::GetVersion() < base::win::VERSION_VISTA)
     return NetworkChangeNotifier::CONNECTION_UNKNOWN;
 
   NetworkChangeNotifier::ConnectionType type =
       NetworkChangeNotifier::CONNECTION_UNKNOWN;
   if (ifType == IF_TYPE_ETHERNET_CSMACD) {
     type = NetworkChangeNotifier::CONNECTION_ETHERNET;
   } else if (ifType == IF_TYPE_IEEE80211) {
     type = NetworkChangeNotifier::CONNECTION_WIFI;
   }
   // TODO(mallinath) - Cellular?
   return type;
 }
 
 }  // namespace
 
+
+base::LazyInstance<WlanApi>::Leaky lazy_wlanapi =
+  LAZY_INSTANCE_INITIALIZER;
+
+WlanApi& WlanApi::GetInstance() {
+  return lazy_wlanapi.Get();
+}
+
+WlanApi::WlanApi() : initialized(false) {
+  // Use an absolute path to load the DLL to avoid DLL preloading attacks.
+  static const wchar_t* const kDLL = L"%WINDIR%\\system32\\wlanapi.dll";
+  wchar_t path[MAX_PATH] = {0};
+  ExpandEnvironmentStrings(kDLL, path, arraysize(path));
+  module = ::LoadLibraryEx(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
+  if (!module)
+    return;
+
+  open_handle_func = reinterpret_cast<WlanOpenHandleFunc>(
+      ::GetProcAddress(module, "WlanOpenHandle"));
+  enum_interfaces_func = reinterpret_cast<WlanEnumInterfacesFunc>(
+      ::GetProcAddress(module, "WlanEnumInterfaces"));
+  query_interface_func = reinterpret_cast<WlanQueryInterfaceFunc>(
+      ::GetProcAddress(module, "WlanQueryInterface"));
+  set_interface_func = reinterpret_cast<WlanSetInterfaceFunc>(
+      ::GetProcAddress(module, "WlanSetInterface"));
+  free_memory_func = reinterpret_cast<WlanFreeMemoryFunc>(
+      ::GetProcAddress(module, "WlanFreeMemory"));
+  close_handle_func = reinterpret_cast<WlanCloseHandleFunc>(
+      ::GetProcAddress(module, "WlanCloseHandle"));
+  initialized = open_handle_func && enum_interfaces_func &&
+      query_interface_func && set_interface_func &&
+      free_memory_func && close_handle_func;
+}
+
 bool GetNetworkList(NetworkInterfaceList* networks, int policy) {
   // GetAdaptersAddresses() may require IO operations.
   base::ThreadRestrictions::AssertIOAllowed();
   bool is_xp = base::win::GetVersion() < base::win::VERSION_VISTA;
   ULONG len = 0;
   ULONG flags = is_xp ? GAA_FLAG_INCLUDE_PREFIX : 0;
   // First get number of networks.
   ULONG result = GetAdaptersAddresses(AF_UNSPEC, flags, NULL, NULL, &len);
   if (result != ERROR_BUFFER_OVERFLOW) {
     // There are 0 networks.
@@ skipping 50 matching lines @@
             for (IP_ADAPTER_PREFIX* prefix = adapter->FirstPrefix; prefix;
                  prefix = prefix->Next) {
               int prefix_family = prefix->Address.lpSockaddr->sa_family;
               IPEndPoint network_endpoint;
               if (prefix_family == family &&
                   network_endpoint.FromSockAddr(prefix->Address.lpSockaddr,
                       prefix->Address.iSockaddrLength) &&
                   IPNumberMatchesPrefix(endpoint.address(),
                                         network_endpoint.address(),
                                         prefix->PrefixLength)) {
-                net_prefix = std::max<size_t>(net_prefix, prefix->PrefixLength);
+                net_prefix = std::max<size_t>(net_prefix,
+                                              prefix->PrefixLength);

[pauljensen, 2014/09/23 14:03:55]

unnecessary change?

[hubbe, 2014/09/23 17:37:50]

Done.

               }
             }
           }
           uint32 index =
               (family == AF_INET) ? adapter->IfIndex : adapter->Ipv6IfIndex;
           // Pick one IPv6 address with least valid lifetime.
           // The reason we are checking |ValidLifeftime| as there is no other
           // way identifying the interface type. Usually (and most likely) temp
           // IPv6 will have a shorter ValidLifetime value then the permanent
           // interface.
@@ skipping 21 matching lines @@
     }
   }
 
   if (ipv6_address.get()) {
     networks->push_back(*(ipv6_address.get()));
   }
   return true;
 }
 
 WifiPHYLayerProtocol GetWifiPHYLayerProtocol() {
-  static base::LazyInstance<WlanApi>::Leaky lazy_wlanapi =
-      LAZY_INSTANCE_INITIALIZER;
-
-  struct WlanApiHandleTraits {
-    typedef HANDLE Handle;
-
-    static bool CloseHandle(HANDLE handle) {
-      return lazy_wlanapi.Get().close_handle_func(handle, NULL) ==
-          ERROR_SUCCESS;
-    }
-    static bool IsHandleValid(HANDLE handle) {
-      return base::win::HandleTraits::IsHandleValid(handle);
-    }
-    static HANDLE NullHandle() {
-      return base::win::HandleTraits::NullHandle();
-    }
-  };
-
-  typedef base::win::GenericScopedHandle<
-      WlanApiHandleTraits,
-      base::win::DummyVerifierTraits> WlanHandle;
-
-  struct WlanApiDeleter {
-    inline void operator()(void* ptr) const {
-      lazy_wlanapi.Get().free_memory_func(ptr);
-    }
-  };
-
-  const WlanApi& wlanapi = lazy_wlanapi.Get();
+  const WlanApi& wlanapi = WlanApi::GetInstance();
   if (!wlanapi.initialized)
     return WIFI_PHY_LAYER_PROTOCOL_NONE;
 
   WlanHandle client;
   DWORD cur_version = 0;
   const DWORD kMaxClientVersion = 2;
   DWORD result = wlanapi.OpenHandle(kMaxClientVersion, &cur_version, &client);
   if (result != ERROR_SUCCESS)
     return WIFI_PHY_LAYER_PROTOCOL_NONE;
 
@@ skipping 41 matching lines @@
       return WIFI_PHY_LAYER_PROTOCOL_B;
     case dot11_phy_type_erp:
       return WIFI_PHY_LAYER_PROTOCOL_G;
     case dot11_phy_type_ht:
       return WIFI_PHY_LAYER_PROTOCOL_N;
     default:
       return WIFI_PHY_LAYER_PROTOCOL_UNKNOWN;
   }
 }
 
+// Note: There is no need to explicitly set the options back
+// as the OS will automatically set them back when the WlanHandle
+// is closed.

[pauljensen, 2014/09/23 14:03:55]

I couldn't find any documentation for this.  Have you seen any?

[hubbe, 2014/09/23 17:37:49]

It's very poorly documented, but the documentation for
wlan_intf_opcode_background_scan_enabled and
wlan_intf_opcode_media_streaming_mode (found here:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms706886(v=vs.85).aspx)
hints at how it actually works, it just doesn't call it out explicitly.

+class WifiOptionSetter : public ScopedWifiOptions {
+ public:
+  WifiOptionSetter(int options) {
+    const WlanApi& wlanapi = WlanApi::GetInstance();
+    if (!wlanapi.initialized)
+      return;
+
+    DWORD cur_version = 0;
+    const DWORD kMaxClientVersion = 2;
+    DWORD result = wlanapi.OpenHandle(
+        kMaxClientVersion, &cur_version, &client_);
+    if (result != ERROR_SUCCESS)
+      return;
+
+    WLAN_INTERFACE_INFO_LIST* interface_list_ptr = NULL;
+    result = wlanapi.enum_interfaces_func(client_, NULL, &interface_list_ptr);
+    if (result != ERROR_SUCCESS)
+      return;
+    scoped_ptr<WLAN_INTERFACE_INFO_LIST, WlanApiDeleter> interface_list(
+        interface_list_ptr);
+
+    for (unsigned i = 0; i < interface_list->dwNumberOfItems; ++i) {
+      WLAN_INTERFACE_INFO* info = &interface_list->InterfaceInfo[i];
+      if (options & WIFI_OPTIONS_DISABLE_SCAN) {
+        BOOL data = false;
+        wlanapi.set_interface_func(client_,
+                                   &info->InterfaceGuid,
+                                   wlan_intf_opcode_background_scan_enabled,
+                                   sizeof(data),
+                                   &data,
+                                   NULL);
+      }
+      if (options & WIFI_OPTIONS_MEDIA_STREAMING_MODE) {
+        BOOL data = true;
+        wlanapi.set_interface_func(client_,
+                                   &info->InterfaceGuid,
+                                   wlan_intf_opcode_media_streaming_mode,
+                                   sizeof(data),
+                                   &data,
+                                   NULL);
+      }
+    }
+  }
+
+ private:
+  WlanHandle client_;
+};
+
+scoped_ptr<ScopedWifiOptions> SetWifiOptions(int options) {
+  return scoped_ptr<ScopedWifiOptions>(new WifiOptionSetter(options));
+}
+
 }  // namespace net