Cast: Allow extension to control wifi options on windows

net/base/net_util_win.cc

Index: net/base/net_util_win.cc
diff --git a/net/base/net_util_win.cc b/net/base/net_util_win.cc
index cac92e39d54bbb391814190d1faf0ed440c61848..448bf85e9688d7ff86b9ce0bf6da45db4e32e1ba 100644
--- a/net/base/net_util_win.cc
+++ b/net/base/net_util_win.cc
@@ -11,6 +11,7 @@
 
 #include "base/files/file_path.h"
 #include "base/lazy_instance.h"
+#include "base/memory/lifetime_interface.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/strings/string_piece.h"
 #include "base/strings/string_util.h"
@@ -36,6 +37,8 @@ struct WlanApi {
   typedef DWORD (WINAPI *WlanQueryInterfaceFunc)(
       HANDLE, const GUID*, WLAN_INTF_OPCODE, VOID*, DWORD*, VOID**,
       WLAN_OPCODE_VALUE_TYPE*);
+  typedef DWORD (WINAPI *WlanSetInterfaceFunc)(
+      HANDLE, const GUID*, WLAN_INTF_OPCODE, DWORD, const VOID*, VOID*);
   typedef VOID (WINAPI *WlanFreeMemoryFunc)(VOID*);
   typedef DWORD (WINAPI *WlanCloseHandleFunc)(HANDLE, VOID*);
 
@@ -54,6 +57,8 @@ struct WlanApi {
         ::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>(
@@ -78,6 +83,7 @@ struct WlanApi {
   WlanOpenHandleFunc open_handle_func;
   WlanEnumInterfacesFunc enum_interfaces_func;
   WlanQueryInterfaceFunc query_interface_func;
+  WlanSetInterfaceFunc set_interface_func;
   WlanFreeMemoryFunc free_memory_func;
   WlanCloseHandleFunc close_handle_func;
   bool initialized;
@@ -215,9 +221,9 @@ bool GetNetworkList(NetworkInterfaceList* networks, int policy) {
   return true;
 }
 
-WifiPHYLayerProtocol GetWifiPHYLayerProtocol() {
-  static base::LazyInstance<WlanApi>::Leaky lazy_wlanapi =
-      LAZY_INSTANCE_INITIALIZER;
+namespace {

[pauljensen, 2014/09/16 15:01:18]

I think moving this up into the anonymous namespace at the top of the file might
be cleaner.

[hubbe, 2014/09/16 21:06:50]

Done.

+base::LazyInstance<WlanApi>::Leaky lazy_wlanapi =
+  LAZY_INSTANCE_INITIALIZER;
 
   struct WlanApiHandleTraits {
     typedef HANDLE Handle;
@@ -243,7 +249,9 @@ WifiPHYLayerProtocol GetWifiPHYLayerProtocol() {
       lazy_wlanapi.Get().free_memory_func(ptr);
     }
   };
+};

[pauljensen, 2014/09/16 15:01:18]

// namespace

[hubbe, 2014/09/16 21:06:51]

No longer relevant.

 
+WifiPHYLayerProtocol GetWifiPHYLayerProtocol() {
   const WlanApi& wlanapi = lazy_wlanapi.Get();
   if (!wlanapi.initialized)
     return WIFI_PHY_LAYER_PROTOCOL_NONE;
@@ -306,4 +314,58 @@ WifiPHYLayerProtocol GetWifiPHYLayerProtocol() {
   }
 }
 
+class WifiOptionSetter : public base::LifetimeInterface {
+ public:
+ WifiOptionSetter(int options) {

[pauljensen, 2014/09/16 15:01:18]

indent

[hubbe, 2014/09/16 21:06:50]

Done (finally configured emacs on my windows box, yay!)

+    const WlanApi& wlanapi = lazy_wlanapi.Get();
+    if (!wlanapi.initialized)
+      return;
+
+    DWORD cur_version = 0;
+    const DWORD kMaxClientVersion = 2;

[pauljensen, 2014/09/16 15:01:18]

Please add a comment about where this 0 and 2 come from and imply.

[hubbe, 2014/09/16 21:06:50]

Gladly, but I don't know. I copied this from line 252

+    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);
+
+    // Assume at most one connected wifi interface.

[pauljensen, 2014/09/16 15:01:18]

"at most one"?  This function appears to loop through all interfaces.  The
comment for SetWifiOptions also says all interfaces.

[hubbe, 2014/09/16 21:06:50]

Oops, removed.

+    WLAN_INTERFACE_INFO* info = NULL;
+    for (unsigned i = 0; i < interface_list->dwNumberOfItems; ++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);
+      }
+    }
+  }
+

[pauljensen, 2014/09/16 15:01:18]

Maybe I'm missing something, but shouldn't there be a destructor here the resets
these options back?

[hubbe, 2014/09/16 21:06:51]

If I'm reading the documentation correctly, the OS sets these options only as
long as some client wants them. This means that when the client handle is
closed, the options are reset.

I also tested this manually to make sure and added a comment to make it less
confusing.

+private:
+  WlanHandle client_;
+};
+
+scoped_ptr<base::LifetimeInterface> SetWifiOptions(int options) {
+  return scoped_ptr<base::LifetimeInterface>(
+      new WifiOptionSetter(options));
+}
+
 }  // namespace net