Use data binding to provide EditText input filters

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>

app/src/main/java/com/wireguard/android/BindingAdapters.java

@@ -4,7 +4,7 @@ import android.databinding.BindingAdapter;
 import android.databinding.ObservableArrayMap;
 import android.databinding.ObservableList;
 import android.graphics.Typeface;
-import android.widget.EditText;
+import android.text.InputFilter;
 import android.widget.ListView;
 import android.widget.TextView;
 
@@ -62,8 +62,13 @@ public final class BindingAdapters {
         }
     }
 
+    @BindingAdapter({"filter"})
+    public static void setFilter(final TextView view, final InputFilter filter) {
+        view.setFilters(new InputFilter[]{filter});
+    }
+
     @BindingAdapter({"android:textStyle"})
-    public static void textStyleBinding(final TextView view, final Typeface typeface) {
+    public static void setTextStyle(final TextView view, final Typeface typeface) {
         view.setTypeface(typeface);
     }
 

app/src/main/java/com/wireguard/android/ConfigEditFragment.java

@@ -2,8 +2,6 @@ package com.wireguard.android;
 
 import android.content.Context;
 import android.os.Bundle;
-import android.text.InputFilter;
-import android.text.LoginFilter;
 import android.view.LayoutInflater;
 import android.view.Menu;
 import android.view.MenuInflater;
@@ -11,7 +9,6 @@ import android.view.MenuItem;
 import android.view.View;
 import android.view.ViewGroup;
 import android.view.inputmethod.InputMethodManager;
-import android.widget.EditText;
 import android.widget.Toast;
 
 import com.wireguard.android.databinding.ConfigEditFragmentBinding;
@@ -45,18 +42,6 @@ public class ConfigEditFragment extends BaseConfigFragment {
                              final Bundle savedInstanceState) {
         final ConfigEditFragmentBinding binding =
                 ConfigEditFragmentBinding.inflate(inflater, parent, false);
-        final EditText configNameText = binding.getRoot().findViewById(R.id.config_name_text);
-        configNameText.setFilters(new InputFilter[]{
-                new InputFilter.LengthFilter(16),
-                new LoginFilter.UsernameFilterGeneric() {
-                    @Override
-                    public boolean isAllowed(final char c) {
-                        return Character.isLetterOrDigit(c) || "_=+.-".indexOf(c) != -1;
-                    }
-                }
-        });
-        final EditText privateKeyText = binding.getRoot().findViewById(R.id.private_key_text);
-        privateKeyText.setFilters(new InputFilter[]{new KeyInputFilter()});
         binding.setConfig(localConfig);
         return binding.getRoot();
     }

app/src/main/java/com/wireguard/android/KeyInputFilter.java

@@ -9,7 +9,12 @@ import com.wireguard.crypto.KeyEncoding;
 /**
  * InputFilter for entering WireGuard private/public keys encoded with base64.
  */
-class KeyInputFilter implements InputFilter {
+
+public class KeyInputFilter implements InputFilter {
+    public static KeyInputFilter newInstance() {
+        return new KeyInputFilter();
+    }
+
     @Override
     public CharSequence filter(final CharSequence source,
                                final int sStart, final int sEnd,

app/src/main/java/com/wireguard/android/NameInputFilter.java

@@ -0,0 +1,46 @@
+package com.wireguard.android;
+
+import android.text.InputFilter;
+import android.text.SpannableStringBuilder;
+import android.text.Spanned;
+
+import com.wireguard.config.Config;
+
+/**
+ * InputFilter for entering WireGuard configuration names (Linux interface names).
+ */
+
+public class NameInputFilter implements InputFilter {
+    public static NameInputFilter newInstance() {
+        return new NameInputFilter();
+    }
+
+    @Override
+    public CharSequence filter(final CharSequence source,
+                               final int sStart, final int sEnd,
+                               final Spanned dest,
+                               final int dStart, final int dEnd) {
+        SpannableStringBuilder replacement = null;
+        int rIndex = 0;
+        final int dLength = dest.length();
+        for (int sIndex = sStart; sIndex < sEnd; ++sIndex) {
+            final char c = source.charAt(sIndex);
+            final int dIndex = dStart + (sIndex - sStart);
+            // Restrict characters to those valid in interfaces.
+            // Ensure adding this character does not push the length over the limit.
+            if ((dIndex < Config.NAME_MAX_LENGTH && isAllowed(c)) &&
+                    dLength + (sIndex - sStart) < Config.NAME_MAX_LENGTH) {
+                ++rIndex;
+            } else {
+                if (replacement == null)
+                    replacement = new SpannableStringBuilder(source, sStart, sEnd);
+                replacement.delete(rIndex, rIndex + 1);
+            }
+        }
+        return replacement;
+    }
+
+    private boolean isAllowed(final char c) {
+        return Character.isLetterOrDigit(c) || "_=+.-".indexOf(c) >= 0;
+    }
+}

app/src/main/java/com/wireguard/config/Config.java

@@ -22,10 +22,11 @@ import java.util.regex.Pattern;
 
 public class Config extends BaseObservable
         implements Comparable<Config>, Copyable<Config>, Observable {
+    public static final int NAME_MAX_LENGTH = 16;
     private static final Pattern PATTERN = Pattern.compile("^[a-zA-Z0-9_=+.-]{1,16}$");
 
     private static boolean isNameValid(final String name) {
-        return PATTERN.matcher(name).matches();
+        return name.length() <= NAME_MAX_LENGTH && PATTERN.matcher(name).matches();
     }
 
     private final Interface iface = new Interface();

app/src/main/res/layout/config_edit_fragment.xml

@@ -1,8 +1,13 @@
 <?xml version="1.0" encoding="utf-8"?>
-<layout xmlns:android="http://schemas.android.com/apk/res/android">
+<layout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto">
 
     <data>
 
+        <import type="com.wireguard.android.KeyInputFilter" />
+
+        <import type="com.wireguard.android.NameInputFilter" />
+
         <variable
             name="config"
             type="com.wireguard.config.Config" />
@@ -32,7 +37,8 @@
                 android:layout_height="wrap_content"
                 android:layout_below="@+id/config_name_label"
                 android:inputType="textCapWords"
-                android:text="@={config.name}" />
+                android:text="@={config.name}"
+                app:filter="@{NameInputFilter.newInstance()}" />
 
             <TextView
                 android:id="@+id/private_key_label"
@@ -50,7 +56,8 @@
                 android:layout_below="@+id/private_key_label"
                 android:layout_toStartOf="@+id/generate_private_key_button"
                 android:inputType="textVisiblePassword"
-                android:text="@={config.interface.privateKey}" />
+                android:text="@={config.interface.privateKey}"
+                app:filter="@{KeyInputFilter.newInstance()}" />
 
             <Button
                 android:id="@+id/generate_private_key_button"