Windows: lazy load wlanapi.dll

Appearently wlanapi.dll (which we use to borrow the wlan password
from the computer running Imager) is not always present on the
server editions of Windows, so only load it if it exists.

Ref #584

src/CMakeLists.txt

@@ -8,8 +8,8 @@ OPTION (ENABLE_TELEMETRY "Enable sending telemetry" ON)
 project(rpi-imager LANGUAGES CXX C)
 set(IMAGER_VERSION_MAJOR 1)
 set(IMAGER_VERSION_MINOR 7)
-set(IMAGER_VERSION_STR "${IMAGER_VERSION_MAJOR}.${IMAGER_VERSION_MINOR}.4.1")
+set(IMAGER_VERSION_STR "${IMAGER_VERSION_MAJOR}.${IMAGER_VERSION_MINOR}.5")
-set(IMAGER_VERSION_CSV "${IMAGER_VERSION_MAJOR},${IMAGER_VERSION_MINOR},4,1")
+set(IMAGER_VERSION_CSV "${IMAGER_VERSION_MAJOR},${IMAGER_VERSION_MINOR},5,0")
 add_definitions(-DIMAGER_VERSION_STR="${IMAGER_VERSION_STR}")
 add_definitions(-DIMAGER_VERSION_CSV=${IMAGER_VERSION_CSV})
 set(CMAKE_INCLUDE_CURRENT_DIR ON)
@@ -48,8 +48,15 @@ elseif (UNIX)
 elseif (WIN32)
     set(DEPENDENCIES acceleratedcryptographichash.cpp dependencies/mountutils/src/windows/functions.cpp dependencies/drivelist/src/windows/list.cpp
         windows/winfile.cpp windows/winfile.h windows/winwlancredentials.h windows/winwlancredentials.cpp
-        windows/rpi-imager.rc)
+        windows/rpi-imager.rc wlanapi_delayed.lib)
-    set(EXTRALIBS setupapi wlanapi)
+    set(EXTRALIBS setupapi ${CMAKE_CURRENT_BINARY_DIR}/wlanapi_delayed.lib)
+    add_custom_command(
+        OUTPUT wlanapi_delayed.lib
+        COMMAND ${CMAKE_DLLTOOL} --input-def "${CMAKE_CURRENT_SOURCE_DIR}/windows/wlanapi.def"
+                --output-delaylib "wlanapi_delayed.lib" --dllname "wlanapi.dll"
+        DEPENDS ${CMAKE_CURRENT_SOURCE_DIR}/windows/wlanapi.def
+        VERBATIM
+    )
 endif()
 
 include_directories(BEFORE .)

src/windows/winwlancredentials.cpp

@@ -8,12 +8,29 @@
 #include <winioctl.h>
 #include <wlanapi.h>
 #include <Windot11.h>
+#include <delayimp.h>
 #include <QDebug>
 #include <QRegularExpression>
 #ifndef WLAN_PROFILE_GET_PLAINTEXT_KEY
 #define WLAN_PROFILE_GET_PLAINTEXT_KEY 4
 #endif
 
+static HINSTANCE hWlanApi = NULL;
+
+/* Called by dlltool generated delaylib code that is used for lazy loading
+   wlanapi.dll */
+FARPROC WINAPI dllDelayNotifyHook(unsigned dliNotify, PDelayLoadInfo)
+{
+    if (dliNotify == dliNotePreLoadLibrary)
+    {
+        return (FARPROC) hWlanApi;
+    }
+
+    return NULL;
+}
+
+PfnDliHook __pfnDliNotifyHook2 = dllDelayNotifyHook;
+
 inline QString unescapeXml(QString str)
 {
     static const char *table[] = {
@@ -35,6 +52,14 @@ inline QString unescapeXml(QString str)
 
 WinWlanCredentials::WinWlanCredentials()
 {
+    if (!hWlanApi)
+        hWlanApi = LoadLibraryExA("wlanapi.dll", NULL, LOAD_LIBRARY_SEARCH_SYSTEM32);
+    if (!hWlanApi)
+    {
+        qDebug() << "wlanapi.dll not available";
+        return;
+    }
+
     /* Get both SSID and PSK in one go, and store it in variables */
     HANDLE h;
     DWORD supportedVersion = 0;

src/windows/wlanapi.def

@@ -0,0 +1,9 @@
+LIBRARY wlanapi
+EXPORTS
+WlanCloseHandle@8
+WlanEnumInterfaces@12
+WlanFreeMemory@4
+WlanGetProfile@28
+WlanGetProfileList@16
+WlanOpenHandle@16
+WlanQueryInterface@28