Define MacAddress class

/*

 * Copyright 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.net;

import com.android.internal.annotations.VisibleForTesting;

import java.util.Arrays;

/**

 * @hide

 */

public final class MacAddress {

    // TODO: add isLocallyAssigned().

    // TODO: add getRandomAddress() factory method.

    private static final int ETHER_ADDR_LEN = 6;

    private static final byte FF = (byte) 0xff;

    @VisibleForTesting

    static final byte[] ETHER_ADDR_BROADCAST = { FF, FF, FF, FF, FF, FF };

    public enum MacAddressType {

        UNICAST,

        MULTICAST,

        BROADCAST;

    }

    /** Return true if the given byte array is not null and has the length of a mac address. */

    public static boolean isMacAddress(byte[] addr) {

        return addr != null && addr.length == ETHER_ADDR_LEN;

    }

    /**

     * Return the MacAddressType of the mac address represented by the given byte array,

     * or null if the given byte array does not represent an mac address. */

    public static MacAddressType macAddressType(byte[] addr) {

        if (!isMacAddress(addr)) {

            return null;

        }

        if (Arrays.equals(addr, ETHER_ADDR_BROADCAST)) {

            return MacAddressType.BROADCAST;

        }

        if ((addr[0] & 0x01) == 1) {

            return MacAddressType.MULTICAST;

        }

        return MacAddressType.UNICAST;

    }

}

/*

 * Copyright 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.net;

import static org.junit.Assert.assertEquals;

import static org.junit.Assert.assertTrue;

import static org.junit.Assert.assertFalse;

import android.net.MacAddress.MacAddressType;

import android.support.test.filters.SmallTest;

import android.support.test.runner.AndroidJUnit4;

import java.util.Arrays;

import org.junit.Test;

import org.junit.runner.RunWith;

@SmallTest

@RunWith(AndroidJUnit4.class)

public class MacAddressTest {

    static class AddrTypeTestCase {

        byte[] addr;

        MacAddressType expected;

        static AddrTypeTestCase of(MacAddressType expected, int... addr) {

            AddrTypeTestCase t = new AddrTypeTestCase();

            t.expected = expected;

            t.addr = toByteArray(addr);

            return t;

        }

    }

    @Test

    public void testMacAddrTypes() {

        AddrTypeTestCase[] testcases = {

            AddrTypeTestCase.of(null),

            AddrTypeTestCase.of(null, 0),

            AddrTypeTestCase.of(null, 1, 2, 3, 4, 5),

            AddrTypeTestCase.of(null, 1, 2, 3, 4, 5, 6, 7),

            AddrTypeTestCase.of(MacAddressType.UNICAST, 0xa0, 0xb0, 0xc0, 0xd0, 0xe0, 0xf0),

            AddrTypeTestCase.of(MacAddressType.BROADCAST, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff),

            AddrTypeTestCase.of(MacAddressType.MULTICAST, 1, 2, 3, 4, 5, 6),

            AddrTypeTestCase.of(MacAddressType.MULTICAST, 11, 22, 33, 44, 55, 66),

            AddrTypeTestCase.of(MacAddressType.MULTICAST, 33, 33, 0xaa, 0xbb, 0xcc, 0xdd)

        };

        for (AddrTypeTestCase t : testcases) {

            MacAddressType got = MacAddress.macAddressType(t.addr);

            String msg = String.format("expected type of %s to be %s, but got %s",

                    Arrays.toString(t.addr), t.expected, got);

            assertEquals(msg, t.expected, got);

        }

    }

    static byte[] toByteArray(int[] in) {

        byte[] out = new byte[in.length];

        for (int i = 0; i < in.length; i++) {

            out[i] = (byte) in[i];

        }

        return out;

    }

}