From d2736fe0351f195421ea7ee6267ee12c6ee40105 Mon Sep 17 00:00:00 2001
From: Oscar Hinton <Hinton@users.noreply.github.com>
Date: Thu, 15 Sep 2022 16:17:09 +0200
Subject: [PATCH] [PS-1469] Ensure the window is focused when prompting for
 biometrics (#3534)

---
 apps/desktop/desktop_native/Cargo.toml        |  2 +
 .../desktop_native/src/biometric/windows.rs   | 55 ++++++++++++++++---
 2 files changed, 49 insertions(+), 8 deletions(-)

diff --git a/apps/desktop/desktop_native/Cargo.toml b/apps/desktop/desktop_native/Cargo.toml
index 1285ef4368..b7d95bf96d 100644
--- a/apps/desktop/desktop_native/Cargo.toml
+++ b/apps/desktop/desktop_native/Cargo.toml
@@ -30,6 +30,8 @@ windows = {version = "0.32.0", features = [
   "Win32_Foundation",
   "Win32_Security_Credentials",
   "Win32_System_WinRT",
+  "Win32_UI_Input_KeyboardAndMouse",
+  "Win32_UI_WindowsAndMessaging",
 ]}
 
 [target.'cfg(windows)'.dev-dependencies]
diff --git a/apps/desktop/desktop_native/src/biometric/windows.rs b/apps/desktop/desktop_native/src/biometric/windows.rs
index d956da064d..f49730cc55 100644
--- a/apps/desktop/desktop_native/src/biometric/windows.rs
+++ b/apps/desktop/desktop_native/src/biometric/windows.rs
@@ -1,19 +1,33 @@
 use anyhow::Result;
 use windows::{
-    core::factory, Foundation::IAsyncOperation, Security::Credentials::UI::*,
-    Win32::Foundation::HWND, Win32::System::WinRT::IUserConsentVerifierInterop,
+    core::{factory, HSTRING},
+    Foundation::IAsyncOperation,
+    Security::Credentials::UI::*,
+    Win32::{
+        Foundation::HWND,
+        System::WinRT::IUserConsentVerifierInterop,
+        UI::{
+            Input::KeyboardAndMouse::{
+                self, keybd_event, GetAsyncKeyState, SetFocus, KEYEVENTF_EXTENDEDKEY,
+                KEYEVENTF_KEYUP, VK_MENU,
+            },
+            WindowsAndMessaging::{self, SetForegroundWindow},
+        },
+    },
 };
 
 pub fn prompt(hwnd: Vec<u8>, message: String) -> Result<bool> {
-    let interop = factory::<UserConsentVerifier, IUserConsentVerifierInterop>()?;
-
-    let h = isize::from_le_bytes(hwnd.try_into().unwrap());
+    let h = isize::from_le_bytes(hwnd.clone().try_into().unwrap());
     let window = HWND(h);
 
-    let operation: IAsyncOperation<UserConsentVerificationResult> =
-        unsafe { interop.RequestVerificationForWindowAsync(window, message)? };
+    // The Windows Hello prompt is displayed inside the application window. For best result we
+    //  should set the window to the foreground and focus it.
+    set_focus(window);
 
-    let result: UserConsentVerificationResult = operation.get()?;
+    let interop = factory::<UserConsentVerifier, IUserConsentVerifierInterop>()?;
+    let operation: IAsyncOperation<UserConsentVerificationResult> =
+        unsafe { interop.RequestVerificationForWindowAsync(window, &HSTRING::from(message))? };
+    let result = operation.get()?;
 
     match result {
         UserConsentVerificationResult::Verified => Ok(true),
@@ -31,6 +45,31 @@ pub fn available() -> Result<bool> {
     }
 }
 
+fn set_focus(window: HWND) {
+    let mut pressed = false;
+
+    unsafe {
+        // Simulate holding down Alt key to bypass windows limitations
+        //  https://docs.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getasynckeystate#return-value
+        //  The most significant bit indicates if the key is currently being pressed. This means the
+        //  value will be negative if the key is pressed.
+        if GetAsyncKeyState(VK_MENU.0 as i32) >= 0 {
+            pressed = true;
+            keybd_event(VK_MENU.0 as u8, 0, KEYEVENTF_EXTENDEDKEY, 0);
+        }
+        SetForegroundWindow(window);
+        SetFocus(window);
+        if pressed {
+            keybd_event(
+                VK_MENU.0 as u8,
+                0,
+                KEYEVENTF_EXTENDEDKEY | KEYEVENTF_KEYUP,
+                0,
+            );
+        }
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;