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Commit 4e5ce390 authored by Philip P. Moltmann's avatar Philip P. Moltmann
Browse files

Implement Luhn checksum algo 

Ignore all non-digits. If only digits should be allowed, the
developer can use a combination of SimpleRegexValidator and
RequiredValidators.

Bug: 62534917
Test: cts-tradefed run cts-dev -m CtsAutoFillServiceTestCases
          --test=android.autofillservice.cts.LuhnChecksumValidatorTest

Change-Id: I4a7c68a236c3d4cb967f1bc61115df89e584a86d
parent 4c79c7b4

api/test-current.txt

+1 −0
Original line number Diff line number Diff line
@@ -37237,6 +37237,7 @@ package android.service.autofill { 
  public final class LuhnChecksumValidator implements android.os.Parcelable {

    ctor public LuhnChecksumValidator(android.view.autofill.AutofillId...);

    method public int describeContents();

    method public boolean isValid(android.service.autofill.ValueFinder);

    method public void writeToParcel(android.os.Parcel, int);

    field public static final android.os.Parcelable.Creator<android.service.autofill.LuhnChecksumValidator> CREATOR;

  }

core/java/android/service/autofill/LuhnChecksumValidator.java

+37 −8
Original line number Diff line number Diff line
@@ -19,9 +19,9 @@ 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.text.TextUtils;

import android.util.Log;

import android.view.autofill.AutofillId;
@@ -29,7 +29,7 @@ import com.android.internal.util.Preconditions; 


/**

 * Validator that returns {@code true} if the number created by concatenating all given fields

 * pass a Luhn algorithm checksum.

 * pass a Luhn algorithm checksum. All non-digits are ignored.

 *

 * <p>See {@link SaveInfo.Builder#setValidator(Validator)} for examples.

 */
@@ -47,8 +47,41 @@ public final class LuhnChecksumValidator extends InternalValidator implements Pa 
        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;
@@ -61,12 +94,8 @@ public final class LuhnChecksumValidator extends InternalValidator implements Pa 
            }

            number.append(partialNumber);

        }

        final boolean isValid = TextUtils.isDigitsOnly(number.toString());

        if (sDebug) Log.d(TAG, "Is valid: " + isValid);

        // TODO(b/62534917): proper implementation - copy & paste code from:

        // PaymentUtils.java

        // PaymentUtilsTest.java

        return isValid;



        return isLuhnChecksumValid(number.toString());

    }



    /////////////////////////////////////