Permanent favicon blacklisting

app/src/main/java/eu/faircode/email/ContactInfo.java

@@ -50,10 +50,8 @@ import java.net.HttpURLConnection;
 import java.net.SocketTimeoutException;
 import java.net.URL;
 import java.nio.charset.StandardCharsets;
-import java.util.ArrayList;
 import java.util.Date;
 import java.util.HashMap;
-import java.util.List;
 import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
@@ -74,7 +72,6 @@ public class ContactInfo {
     private static Map<String, Lookup> emailLookup = new ConcurrentHashMap<>();
     private static final Map<String, ContactInfo> emailContactInfo = new HashMap<>();
     private static final Map<String, Avatar> emailGravatar = new HashMap<>();
-    private static final List<String> emailFaviconBlacklist = new ArrayList<>();
 
     private static final ExecutorService executor =
             Helper.getBackgroundExecutor(1, "contact");
@@ -119,10 +116,26 @@ public class ContactInfo {
         return (new Date().getTime() - time > CACHE_CONTACT_DURATION);
     }
 
-    static void clearCache() {
+    static void clearCache(Context context) {
         synchronized (emailContactInfo) {
             emailContactInfo.clear();
         }
+
+        final File dir = new File(context.getCacheDir(), "favicons");
+
+        executor.submit(new Runnable() {
+            @Override
+            public void run() {
+                try {
+                    File[] favicons = dir.listFiles();
+                    if (favicons != null)
+                        for (File favicon : favicons)
+                            favicon.delete();
+                } catch (Throwable ex) {
+                    Log.w(ex);
+                }
+            }
+        });
     }
 
     @NonNull
@@ -265,25 +278,22 @@ public class ContactInfo {
             int at = (info.email == null ? -1 : info.email.indexOf('@'));
             String domain = (at < 0 ? null : info.email.substring(at + 1).toLowerCase(Locale.ROOT));
 
-            synchronized (emailFaviconBlacklist) {
-                if (emailFaviconBlacklist.contains(domain)) {
-                    Log.i("Favicon blacklisted domain=" + domain);
-                    domain = null;
-                }
-            }
-
             if (domain != null) {
                 if ("gmail.com".equals(domain))
                     domain = "google.com";
 
+                File dir = new File(context.getCacheDir(), "favicons");
+                if (!dir.exists())
+                    dir.mkdir();
+                File file = new File(dir, domain);
+
                 try {
                     // check cache
-                    File dir = new File(context.getCacheDir(), "favicons");
-                    if (!dir.exists())
-                        dir.mkdir();
-                    File file = new File(dir, domain);
                     if (file.exists())
-                        info.bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
+                        if (file.length() == 0)
+                            Log.i("Favicon blacklisted domain=" + domain);
+                        else
+                            info.bitmap = BitmapFactory.decodeFile(file.getAbsolutePath());
                     else {
                         info.bitmap = getFavicon(new URL("https://" + domain));
                         if (info.bitmap == null)
@@ -299,8 +309,10 @@ public class ContactInfo {
                     Log.w(ex);
                 } finally {
                     if (info.bitmap == null)
-                        synchronized (emailFaviconBlacklist) {
+                        try {
-                            emailFaviconBlacklist.add(domain);
+                            file.createNewFile();
+                        } catch (IOException ex) {
+                            Log.e(ex);
                         }
                 }
             }

app/src/main/java/eu/faircode/email/FragmentOptionsDisplay.java

@@ -334,7 +334,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("avatars", checked).apply();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -342,7 +342,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("gravatars", checked).apply();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -350,7 +350,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("favicons", checked).apply();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -370,7 +370,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
                 sbSaturation.setEnabled(checked);
                 sbBrightness.setEnabled(checked);
                 sbThreshold.setEnabled(checked);
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -378,7 +378,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             @Override
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("identicons", checked).apply();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -387,7 +387,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             public void onCheckedChanged(CompoundButton compoundButton, boolean checked) {
                 prefs.edit().putBoolean("circular", checked).apply();
                 updateColor();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
         });
 
@@ -396,7 +396,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                 prefs.edit().putInt("saturation", progress).apply();
                 updateColor();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
 
             @Override
@@ -415,7 +415,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                 prefs.edit().putInt("brightness", progress).apply();
                 updateColor();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
 
             @Override
@@ -434,7 +434,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
             public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                 prefs.edit().putInt("threshold", progress).apply();
                 updateColor();
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(getContext());
             }
 
             @Override
@@ -1023,7 +1023,7 @@ public class FragmentOptionsDisplay extends FragmentBase implements SharedPrefer
                         public void onClick(DialogInterface dialog, int which) {
                             getActivity().getIntent().putExtra("tab", "display");
 
-                            ContactInfo.clearCache();
+                            ContactInfo.clearCache(getContext());
 
                             boolean reverse = (swReverse.isEnabled() && swReverse.isChecked());
                             boolean dark = (swDark.isEnabled() && swDark.isChecked());

app/src/main/java/eu/faircode/email/WorkerCleanup.java

@@ -124,7 +124,7 @@ public class WorkerCleanup extends Worker {
                 ServiceSynchronize.reschedule(context);
 
                 // Contact info cache
-                ContactInfo.clearCache();
+                ContactInfo.clearCache(context);
 
                 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {
                     Log.i("Checking notification channels");