Add auth protection for ssh key export

We use a builtin keyguard for ssh key export protection on Android.

This protection works only if some protection is set on the phone.

https://developer.android.com/reference/android/app/KeyguardManager#isDeviceSecure()

client/android/src/org/amnezia/vpn/AuthHelper.java

@@ -0,0 +1,24 @@
+package org.amnezia.vpn;
+
+import android.content.Context;
+import android.app.KeyguardManager;
+import android.content.Intent;
+import org.qtproject.qt5.android.bindings.QtActivity;
+
+
+import static android.content.Context.KEYGUARD_SERVICE;
+
+public class AuthHelper extends QtActivity {
+
+   static final String TAG = "AuthHelper";
+  
+   public static Intent getAuthIntent(Context context) {
+   	KeyguardManager mKeyguardManager = (KeyguardManager)context.getSystemService(KEYGUARD_SERVICE);
+   	if (mKeyguardManager.isDeviceSecure()) {
+                return mKeyguardManager.createConfirmDeviceCredentialIntent(null, null);
+        } else {
+        	return null;
+        }     
+   }
+   
+}

client/ui/pages_logic/ServerSettingsLogic.cpp

@@ -10,6 +10,12 @@
 #include <core/servercontroller.h>
 #include <QTimer>
 
+#if defined(Q_OS_ANDROID)
+#include <QAndroidJniObject>
+#include <QAndroidJniEnvironment>
+#include <QtAndroid>
+#endif
+
 ServerSettingsLogic::ServerSettingsLogic(UiLogic *logic, QObject *parent):
     PageLogicBase(logic, parent),
     m_labelWaitInfoVisible{true},
@@ -126,8 +132,41 @@ void ServerSettingsLogic::onLineEditDescriptionEditingFinished()
     uiLogic()->onUpdateAllPages();
 }
 
+#if defined(Q_OS_ANDROID)
+/* Auth result handler for Android */
+void authResultReceiver::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data)
+{
+    qDebug() << "receiverRequestCode" << receiverRequestCode << "resultCode" << resultCode;
+
+    if (resultCode == -1) { //ResultOK
+        uiLogic()->pageLogic<ShareConnectionLogic>()->updateSharingPage(m_serverIndex, DockerContainer::None);
+        emit uiLogic()->goToShareProtocolPage(Proto::Any);
+    }
+}
+#endif
+
 void ServerSettingsLogic::onPushButtonShareFullClicked()
 {
+#if defined(Q_OS_ANDROID)
+/* We use builtin keyguard for ssh key export protection on Android */
+    auto appContext = QtAndroid::androidActivity().callObjectMethod(
+        "getApplicationContext", "()Landroid/content/Context;");
+    if (appContext.isValid()) {
+        QAndroidActivityResultReceiver *receiver = new authResultReceiver(uiLogic(), uiLogic()->selectedServerIndex);
+        auto intent = QAndroidJniObject::callStaticObjectMethod(
+               "org/amnezia/vpn/AuthHelper", "getAuthIntent",
+               "(Landroid/content/Context;)Landroid/content/Intent;", appContext.object());
+        if (intent.isValid()) {
+            if (intent.object<jobject>() != nullptr) {
+                    QtAndroid::startActivity(intent.object<jobject>(), 1, receiver);
+                }
+            } else {
             uiLogic()->pageLogic<ShareConnectionLogic>()->updateSharingPage(uiLogic()->selectedServerIndex, DockerContainer::None);
             emit uiLogic()->goToShareProtocolPage(Proto::Any);
         }
+    }
+#else
+    uiLogic()->pageLogic<ShareConnectionLogic>()->updateSharingPage(uiLogic()->selectedServerIndex, DockerContainer::None);
+    emit uiLogic()->goToShareProtocolPage(Proto::Any);
+#endif
+}

client/ui/pages_logic/ServerSettingsLogic.h

@@ -3,6 +3,10 @@
 
 #include "PageLogicBase.h"
 
+#if defined(Q_OS_ANDROID)
+#include <QAndroidActivityResultReceiver>
+#endif
+
 class UiLogic;
 
 class ServerSettingsLogic : public PageLogicBase
@@ -34,4 +38,25 @@ public:
     ~ServerSettingsLogic() = default;
 
 };
+
+#if defined(Q_OS_ANDROID)
+/* Auth result handler for Android */
+class authResultReceiver  final : public PageLogicBase, public QAndroidActivityResultReceiver
+{
+Q_OBJECT
+
+public:
+    authResultReceiver(UiLogic *uiLogic, int serverIndex , QObject *parent = nullptr) : PageLogicBase(uiLogic, parent) {
+        m_serverIndex = serverIndex;
+    }
+    ~authResultReceiver() {}
+
+public:
+    void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data) override;
+
+private:
+    int  m_serverIndex;
+};
+#endif
+
 #endif // SERVER_SETTINGS_LOGIC_H