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package com.wireguard.android.widget;
import android.text.InputFilter;
import android.text.SpannableStringBuilder;
import android.text.Spanned;
import com.wireguard.crypto.KeyEncoding;
/**
* InputFilter for entering WireGuard private/public keys encoded with base64.
*/
public class KeyInputFilter implements InputFilter {
private static boolean isAllowed(final char c) {
return Character.isLetterOrDigit(c) || c == '+' || c == '/';
}
public static InputFilter newInstance() {
return new KeyInputFilter();
}
@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 the base64 character set.
// Ensure adding this character does not push the length over the limit.
if (((dIndex + 1 < KeyEncoding.KEY_LENGTH_BASE64 && isAllowed(c)) ||
(dIndex + 1 == KeyEncoding.KEY_LENGTH_BASE64 && c == '=')) &&
dLength + (sIndex - sStart) < KeyEncoding.KEY_LENGTH_BASE64) {
++rIndex;
} else {
if (replacement == null)
replacement = new SpannableStringBuilder(source, sStart, sEnd);
replacement.delete(rIndex, rIndex + 1);
}
}
return replacement;
}
}
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