improve user experience with autofill security alert:

* remember trusted links
 * allow to make an app trusted
 * improve message by displaying application label instead of package name (show package name once for security)

src/keepass2android/Resources/values/strings.xml

@@ -1232,8 +1232,8 @@ Initial public release
 
 
   <string name="AutofillWarning_title">Security Alert: Unrecognized domain/package link</string>
-  <string name="AutofillWarning_Intro">You are about to insert credentials for domain "%1$s" into the app with package name "%2$s".</string>
+  <string name="AutofillWarning_Intro">You are about to insert credentials for domain "%1$s" into the app "%2$s".</string>
   <string name="AutofillWarning_FillDomainInUntrustedApp">If you trust "%2$s" to belong to "%1$s" or you trust the app "%2$s" not to misuse the credentials (e.g. because it is a trusted browser app), it is ok to continue. If not, please cancel.</string>
-  <string name="AutofillWarning_continue">Security Alert: Unrecognized domain/package link</string>
+  <string name="AutofillWarning_trustAsBrowser">Accept always in "%1$s"</string>
 
 </resources>

src/keepass2android/services/AutofillBase/ChooseForAutofillActivityBase.cs

@@ -10,13 +10,13 @@ using Android.Views.Autofill;
 using Android.Widget;
 using Java.Util;
 using keepass2android.services.AutofillBase.model;
-using System.Collections.Generic;
 using System.Linq;
+using Android.Content.PM;
+using Com.Dropbox.Core.V2.Teamlog;
 using AlertDialog = Android.App.AlertDialog;
 
 namespace keepass2android.services.AutofillBase
 {
-
     public abstract class ChooseForAutofillActivityBase : AndroidX.AppCompat.App.AppCompatActivity
     {
         protected Intent ReplyIntent;
@@ -51,6 +51,7 @@ namespace keepass2android.services.AutofillBase
                 RestartApp();
                 return;
             }
+            
             if (Intent.HasExtra(ExtraDisplayWarning))
             {
                 AutofillServiceBase.DisplayWarning warning =
@@ -60,22 +61,56 @@ namespace keepass2android.services.AutofillBase
                     AlertDialog.Builder builder = new AlertDialog.Builder(this);
                     builder.SetTitle(this.GetString(Resource.String.AutofillWarning_title));
 
+                    string appName = Intent.GetStringExtra(ExtraQueryPackageString);
+                    string appNameWithPackage = appName;
+                    try
+                    {
+                        var appInfo = PackageManager.GetApplicationInfo(appName, 0);
+                        if (appInfo != null)
+                        {
+                            appName = PackageManager.GetApplicationLabel(appInfo);
+                            appNameWithPackage = appName + " (" + Intent.GetStringExtra(ExtraQueryPackageString) + ")";
+                        }
+
+
+                    }
+                    catch (Exception)
+                    {
+                        // ignored
+                    }
+
                     builder.SetMessage(
-                            GetString(Resource.String.AutofillWarning_Intro, new Java.Lang.Object[] { Intent.GetStringExtra(ExtraQueryDomainString), Intent.GetStringExtra(ExtraQueryPackageString) }) 
+                            GetString(Resource.String.AutofillWarning_Intro, new Java.Lang.Object[]
+                            {
+                                Intent.GetStringExtra(ExtraQueryDomainString), appNameWithPackage
+                            }) 
                             + " " + 
-                            this.GetString(Resource.String.AutofillWarning_FillDomainInUntrustedApp, new Java.Lang.Object[] { Intent.GetStringExtra(ExtraQueryDomainString), Intent.GetStringExtra(ExtraQueryPackageString) }));
+                            this.GetString(Resource.String.AutofillWarning_FillDomainInUntrustedApp, new Java.Lang.Object[]
+                            {
+                                Intent.GetStringExtra(ExtraQueryDomainString), appName
+                            }));
 
                     builder.SetPositiveButton(this.GetString(Resource.String.Continue),
                         (dlgSender, dlgEvt) =>
                         {
+                            new Kp2aDigitalAssetLinksDataSource(this).RememberTrustedLink(Intent.GetStringExtra(ExtraQueryDomainString),
+                                Intent.GetStringExtra(ExtraQueryPackageString));
                             Proceed();
 
                         });
+                    builder.SetNeutralButton(this.GetString(Resource.String.AutofillWarning_trustAsBrowser, new Java.Lang.Object[]
+                    {appName}),
+                        (sender, args) =>
+                        {
+                            new Kp2aDigitalAssetLinksDataSource(this).RememberAsTrustedApp(Intent.GetStringExtra(ExtraQueryPackageString));
+                            Proceed();
+                        });
 
                     builder.SetNegativeButton(this.GetString(Resource.String.cancel), (dlgSender, dlgEvt) =>
                     {
                         Finish();
                     });
+                    
 
                     Dialog dialog = builder.Create();
                     dialog.Show();
@@ -86,6 +121,7 @@ namespace keepass2android.services.AutofillBase
             Proceed();
         }
 
+
         private void Proceed()
         {
             string requestedUrl = Intent.GetStringExtra(ExtraQueryString);

src/keepass2android/services/AutofillBase/Kp2aDigitalAssetLinksDataSource.cs

@@ -1,33 +1,65 @@
 using System.Collections.Generic;
+using System.Linq;
 using Android.Content;
+using Android.Preferences;
 
 namespace keepass2android.services.AutofillBase
 {
 
     internal class Kp2aDigitalAssetLinksDataSource
     {
-        private static Kp2aDigitalAssetLinksDataSource instance;
 
-        private Kp2aDigitalAssetLinksDataSource() { }
+        private const string Autofilltrustedapps = "AutoFillTrustedApps";
+        private readonly Context _ctx;
 
-        public static Kp2aDigitalAssetLinksDataSource Instance
+        public Kp2aDigitalAssetLinksDataSource(Context ctx)
         {
-            get
+            _ctx = ctx;
-            {
-                if (instance == null)
-                {
-                    instance = new Kp2aDigitalAssetLinksDataSource();
-                }
-                return instance;
-            }
         }
 
-        public bool IsValid(Context context, string webDomain, string packageName)
+        public bool IsTrustedApp(string packageName)
         {
-            return (IsTrustedBrowser(packageName));
+            if (_trustedBrowsers.Contains(packageName))
+                return true;
+            var prefs = PreferenceManager.GetDefaultSharedPreferences(_ctx);
+            var trustedApps = prefs.GetStringSet(Autofilltrustedapps, new List<string>()).ToHashSet();
+            return trustedApps.Contains(packageName);
+        }
+
+        public bool IsTrustedLink(string domain, string targetPackage)
+        {
+            //we can fill everything into trusted apps (aka browsers)
+            if (IsTrustedApp(targetPackage))
+                return true;
+            //see if the user explicitly allows to fill credentials for domain into targetPackage:
+            var prefs = PreferenceManager.GetDefaultSharedPreferences(_ctx);
+            var trustedLinks = prefs.GetStringSet("AutoFillTrustedLinks", new List<string>()).ToHashSet();
+            return trustedLinks.Contains(BuildLink(domain, targetPackage));
+        }
+
+        public void RememberAsTrustedApp(string packageName)
+        {
+            var prefs = PreferenceManager.GetDefaultSharedPreferences(_ctx);
+            var trustedApps = prefs.GetStringSet(Autofilltrustedapps, new List<string>()).ToHashSet();
+            trustedApps.Add(packageName);
+            prefs.Edit().PutStringSet(Autofilltrustedapps, trustedApps).Commit();
 
         }
 
+        public void RememberTrustedLink(string domain, string package)
+        {
+            var prefs = PreferenceManager.GetDefaultSharedPreferences(_ctx);
+            var trustedLinks = prefs.GetStringSet("AutoFillTrustedLinks", new List<string>()).ToHashSet();
+            trustedLinks.Add(BuildLink(domain, package));
+            prefs.Edit().PutStringSet("AutoFillTrustedLinks", trustedLinks).Commit();
+        }
+
+        private static string BuildLink(string domain, string package)
+        {
+            return domain + " + " + package;
+        }
+
+
         static readonly HashSet<string> _trustedBrowsers = new HashSet<string>
         {
             "org.mozilla.firefox","org.mozilla.firefox_beta","org.mozilla.klar","org.mozilla.focus",
@@ -41,9 +73,5 @@ namespace keepass2android.services.AutofillBase
             "acr.browser.lightning", "acr.browser.barebones", "jp.hazuki.yuzubrowser"
         };
 
-        private bool IsTrustedBrowser(string packageName)
-        {
-            return _trustedBrowsers.Contains(packageName);
-        }
     }
 }

src/keepass2android/services/AutofillBase/StructureParser.cs

@@ -31,7 +31,8 @@ namespace keepass2android.services.AutofillBase
         public string PackageId { get; set; }
 
 		public StructureParser(Context context, AssistStructure structure)
-		{
+        {
+            kp2aDigitalAssetLinksDataSource = new Kp2aDigitalAssetLinksDataSource(context);
 		    mContext = context;
 		    Structure = structure;
 			AutofillFields = new AutofillFieldMetadataCollection();
@@ -176,7 +177,7 @@ namespace keepass2android.services.AutofillBase
             result.PackageName = Structure.ActivityComponent.PackageName;
             if (!string.IsNullOrEmpty(webDomain))
 		    {
-                result.IncompatiblePackageAndDomain = !Kp2aDigitalAssetLinksDataSource.Instance.IsValid(mContext, webDomain, result.PackageName);
+                result.IncompatiblePackageAndDomain = !kp2aDigitalAssetLinksDataSource.IsTrustedLink(webDomain, result.PackageName);
 		        if (result.IncompatiblePackageAndDomain)
 		        {   
 					CommonUtil.loge($"DAL verification failed for {result.PackageName}/{result.WebDomain}");
@@ -196,6 +197,8 @@ namespace keepass2android.services.AutofillBase
         }
 
         private static readonly HashSet<string> _usernameHints = new HashSet<string> { "email","e-mail","username" };
+        private Kp2aDigitalAssetLinksDataSource kp2aDigitalAssetLinksDataSource;
+
         private static bool HasUsernameHint(AssistStructure.ViewNode f)
         {
             return ContainsAny(f.IdEntry, _usernameHints) ||