| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.service.autofill; |
| |
| import static android.view.autofill.Helper.sDebug; |
| |
| import android.annotation.NonNull; |
| import android.annotation.TestApi; |
| import android.os.Parcel; |
| import android.os.Parcelable; |
| import android.util.Log; |
| import android.view.autofill.AutofillId; |
| |
| import com.android.internal.util.Preconditions; |
| |
| import java.util.Arrays; |
| |
| /** |
| * Validator that returns {@code true} if the number created by concatenating all given fields |
| * pass a Luhn algorithm checksum. All non-digits are ignored. |
| * |
| * <p>See {@link SaveInfo.Builder#setValidator(Validator)} for examples. |
| */ |
| public final class LuhnChecksumValidator extends InternalValidator implements Validator, |
| Parcelable { |
| private static final String TAG = "LuhnChecksumValidator"; |
| |
| private final AutofillId[] mIds; |
| |
| /** |
| * Default constructor. |
| * |
| * @param ids id of fields that comprises the number to be checked. |
| */ |
| public LuhnChecksumValidator(@NonNull AutofillId... ids) { |
| mIds = Preconditions.checkArrayElementsNotNull(ids, "ids"); |
| } |
| |
| /** |
| * Checks if the Luhn checksum is valid. |
| * |
| * @param number The number including the checksum |
| */ |
| private static boolean isLuhnChecksumValid(@NonNull String number) { |
| int sum = 0; |
| boolean isDoubled = false; |
| |
| for (int i = number.length() - 1; i >= 0; i--) { |
| final int digit = number.charAt(i) - '0'; |
| if (digit < 0 || digit > 9) { |
| // Ignore non-digits |
| continue; |
| } |
| |
| int addend; |
| if (isDoubled) { |
| addend = digit * 2; |
| if (addend > 9) { |
| addend -= 9; |
| } |
| } else { |
| addend = digit; |
| } |
| sum += addend; |
| isDoubled = !isDoubled; |
| } |
| |
| return sum % 10 == 0; |
| } |
| |
| /** @hide */ |
| @Override |
| @TestApi |
| public boolean isValid(@NonNull ValueFinder finder) { |
| if (mIds == null || mIds.length == 0) return false; |
| |
| final StringBuilder builder = new StringBuilder(); |
| for (AutofillId id : mIds) { |
| final String partialNumber = finder.findByAutofillId(id); |
| if (partialNumber == null) { |
| if (sDebug) Log.d(TAG, "No partial number for id " + id); |
| return false; |
| } |
| builder.append(partialNumber); |
| } |
| |
| final String number = builder.toString(); |
| boolean valid = isLuhnChecksumValid(number); |
| if (sDebug) Log.d(TAG, "isValid(" + number.length() + " chars): " + valid); |
| return valid; |
| } |
| |
| @Override |
| public String toString() { |
| if (!sDebug) return super.toString(); |
| |
| return "LuhnChecksumValidator: [ids=" + Arrays.toString(mIds) + "]"; |
| } |
| |
| ///////////////////////////////////// |
| // Parcelable "contract" methods. // |
| ///////////////////////////////////// |
| @Override |
| public int describeContents() { |
| return 0; |
| } |
| |
| @Override |
| public void writeToParcel(Parcel parcel, int flags) { |
| parcel.writeParcelableArray(mIds, flags); |
| } |
| |
| public static final Parcelable.Creator<LuhnChecksumValidator> CREATOR = |
| new Parcelable.Creator<LuhnChecksumValidator>() { |
| @Override |
| public LuhnChecksumValidator createFromParcel(Parcel parcel) { |
| return new LuhnChecksumValidator(parcel.readParcelableArray(null, AutofillId.class)); |
| } |
| |
| @Override |
| public LuhnChecksumValidator[] newArray(int size) { |
| return new LuhnChecksumValidator[size]; |
| } |
| }; |
| } |