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Commit b483607a authored by xshu's avatar xshu
Browse files

Followup to CL 1103896 

Optimizes the logic that ensures the default randomized MAC is not
returned.

Bug: 137796328
Test: atest MacAddressTest
Change-Id: Ie95d7a020bfac8850b8a67e4d396de77db22e1db
parent bc637172

core/java/android/net/MacAddress.java

+12 −13
Original line number Diff line number Diff line
@@ -85,6 +85,9 @@ public final class MacAddress implements Parcelable { 
    private static final long OUI_MASK = MacAddress.fromString("ff:ff:ff:0:0:0").mAddr;

    private static final long NIC_MASK = MacAddress.fromString("0:0:0:ff:ff:ff").mAddr;

    private static final MacAddress BASE_GOOGLE_MAC = MacAddress.fromString("da:a1:19:0:0:0");

    /** Default wifi MAC address used for a special purpose **/

    private static final MacAddress DEFAULT_MAC_ADDRESS =

            MacAddress.fromString(WifiInfo.DEFAULT_MAC_ADDRESS);



    // Internal representation of the MAC address as a single 8 byte long.

    // The encoding scheme sets the two most significant bytes to 0. The 6 bytes of the
@@ -361,16 +364,7 @@ public final class MacAddress implements Parcelable { 
     * @hide

     */

    public static @NonNull MacAddress createRandomUnicastAddress() {

        SecureRandom r = new SecureRandom();

        long addr = r.nextLong() & VALID_LONG_MASK;

        addr |= LOCALLY_ASSIGNED_MASK;

        addr &= ~MULTICAST_MASK;

        MacAddress mac = new MacAddress(addr);

        // WifiInfo.DEFAULT_MAC_ADDRESS is being used for another purpose, so do not use it here.

        if (mac.toString().equals(WifiInfo.DEFAULT_MAC_ADDRESS)) {

            return createRandomUnicastAddress();

        }

        return mac;

        return createRandomUnicastAddress(null, new SecureRandom());

    }



    /**
@@ -380,18 +374,23 @@ public final class MacAddress implements Parcelable { 
     * The locally assigned bit is always set to 1. The multicast bit is always set to 0.

     *

     * @param base a base MacAddress whose OUI is used for generating the random address.

     *             If base == null then the OUI will also be randomized.

     * @param r a standard Java Random object used for generating the random address.

     * @return a random locally assigned MacAddress.

     *

     * @hide

     */

    public static @NonNull MacAddress createRandomUnicastAddress(MacAddress base, Random r) {

        long addr = (base.mAddr & OUI_MASK) | (NIC_MASK & r.nextLong());

        long addr;

        if (base == null) {

            addr = r.nextLong() & VALID_LONG_MASK;

        } else {

            addr = (base.mAddr & OUI_MASK) | (NIC_MASK & r.nextLong());

        }

        addr |= LOCALLY_ASSIGNED_MASK;

        addr &= ~MULTICAST_MASK;

        MacAddress mac = new MacAddress(addr);

        // WifiInfo.DEFAULT_MAC_ADDRESS is being used for another purpose, so do not use it here.

        if (mac.toString().equals(WifiInfo.DEFAULT_MAC_ADDRESS)) {

        if (mac.equals(DEFAULT_MAC_ADDRESS)) {

            return createRandomUnicastAddress(base, r);

        }

        return mac;