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Commit 5ec3a067 authored by Tyler Gunn's avatar Tyler Gunn
Browse files

Add dial string validation for FAC codes. 

FAC codes are formatted as:
#FAC#MSISDN*

The existing implementation just checked for a matching known FAC code
in carrier config and then just skipped processing it as a USSD/MMI and
dialed it as is.

It turns out in some regions, carriers have FAC codes that mean something
completely different than the same code dialed as a UUSD.

So, *#112*6505551212# and #112#6505551212* do something different 🙄.

To fix this, as part of the validation for a FAC code, we'll also verify
that the original dial string matches the expected format for an FAC code.
This ensures the aforementioned cases get handled as expected; in the
formed case as a USSD/MMI, and in the latter case as an FAC code.

Test: Added new unit test cases for this.
Test: Ran unit tests.
Fixes: 330528194
Change-Id: I74a680f31f6a9f4704d8cf80df397fca4cb01d37
parent bda9f8cd

src/java/com/android/internal/telephony/gsm/GsmMmiCode.java

+26 −2
Original line number Diff line number Diff line
@@ -200,6 +200,12 @@ public final class GsmMmiCode extends Handler implements MmiCode { 
         10 = dialing number

*/



    /**

     * An FAC code is of the following format:

     * #FAC#MSISDN*

     */

    static Pattern sFac = Pattern.compile("^\\#\\d+\\#[^*]+\\*$");



    static final int MATCH_GROUP_POUND_STRING = 1;



    static final int MATCH_GROUP_ACTION = 2;
@@ -274,7 +280,9 @@ public final class GsmMmiCode extends Handler implements MmiCode { 
                // in India operator(Mumbai MTNL)

                ret = new GsmMmiCode(phone, app);

                ret.mPoundString = dialString;

            } else if (ret.isFacToDial()) {

            } else if (ret.isFacToDial(dialString)) {

                // Note: we had to pass in the dial string above because the full dial string is not

                // in the MmiCode class (or even needed there).

                // This is a FAC (feature access code) to dial as a normal call.

                ret = null;

            }
@@ -962,13 +970,29 @@ public final class GsmMmiCode extends Handler implements MmiCode { 
        }

    }



    /**

     * Determines if a full dial string matches the general format of a FAC code.

     * Ie. #FAC#MSIDN*

     * @param dialString The full dialed number.

     * @return {@code true} if the dialed number has the general format of a FAC code.

     */

    private static boolean isFacFormatNumber(String dialString) {

        Matcher m = sFac.matcher(dialString);

        return m.matches();

    }



    /**

     * Returns true if the Service Code is FAC to dial as a normal call.

     *

     * FAC stands for feature access code and it is special patterns of characters

     * to invoke certain features.

     */

    private boolean isFacToDial() {

    private boolean isFacToDial(String dialString) {

        if (!isFacFormatNumber(dialString)) {

            // If the full dial string doesn't conform to the required format for a FAC, we will

            // bail early. It is likely a true USSD which shares the same code as the FAC.

            return false;

        }

        CarrierConfigManager configManager = (CarrierConfigManager)

                mPhone.getContext().getSystemService(Context.CARRIER_CONFIG_SERVICE);

        PersistableBundle b = configManager.getConfigForSubId(mPhone.getSubId());

tests/telephonytests/src/com/android/internal/telephony/gsm/GsmMmiCodeTest.java

+41 −0
Original line number Diff line number Diff line
@@ -20,12 +20,15 @@ import static com.google.common.truth.Truth.assertThat; 


import static junit.framework.Assert.fail;



import static org.junit.Assert.assertNotNull;

import static org.junit.Assert.assertNull;

import static org.junit.Assert.assertTrue;

import static org.mockito.ArgumentMatchers.anyInt;

import static org.mockito.Mockito.doReturn;

import static org.mockito.Mockito.eq;

import static org.mockito.Mockito.verify;



import android.content.Context;

import android.os.AsyncResult;

import android.os.PersistableBundle;

import android.telephony.CarrierConfigManager;
@@ -332,6 +335,44 @@ public class GsmMmiCodeTest extends TelephonyTest { 
                eq(com.android.internal.R.string.mmiErrorNotSupported));

    }



    @Test

    public void testFacCode() {

        // Put a valid FAC code into the carrier config.

        CarrierConfigManager ccm = (CarrierConfigManager) mGsmCdmaPhoneUT.getContext()

                .getSystemService(Context.CARRIER_CONFIG_SERVICE);

        PersistableBundle cc = ccm.getConfigForSubId(0);

        cc.putStringArray(CarrierConfigManager.KEY_FEATURE_ACCESS_CODES_STRING_ARRAY,

                new String[] {"112"});



        // Try using a dial string with the FAC; this should result in a NULL GsmMmiCode.

        GsmMmiCode validFac = GsmMmiCode.newFromDialString("#112#6505551212*", mGsmCdmaPhoneUT,

                null, null);

        assertNull(validFac);



        // Try using a dial string with the FAC; this should result in a NULL GsmMmiCode.

        // Note this case is somewhat contrived, however the GsmMmiCode parsing does allow non-digit

        // characters, so we will here too.

        GsmMmiCode validFac2 = GsmMmiCode.newFromDialString("#112#650-555-1212*", mGsmCdmaPhoneUT,

                null, null);

        assertNull(validFac2);



        // Try using a dial string with a different made up FAC; this one is not in the carrier

        // config so should just return an MMI code.

        GsmMmiCode invalidFac = GsmMmiCode.newFromDialString("#113#6505551212*", mGsmCdmaPhoneUT,

                null, null);

        assertNotNull(invalidFac);



        // Now try the carrier config FAC code, but it's formatted as if it a USSD.

        GsmMmiCode ussd = GsmMmiCode.newFromDialString("*#112*6505551212#", mGsmCdmaPhoneUT,

                null, null);

        assertNotNull(ussd);



        // Now try the carrier config FAC code, but it's not a valid FAC formatted string

        GsmMmiCode invalidFormat = GsmMmiCode.newFromDialString("*#112*6505551212", mGsmCdmaPhoneUT,

                null, null);

        assertNull(invalidFormat);

    }



    private void setCarrierSupportsCallerIdVerticalServiceCodesCarrierConfig() {

        final PersistableBundle bundle = new PersistableBundle();

        bundle.putBoolean(CarrierConfigManager