android.net.MacAddress Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of android-all Show documentation
Show all versions of android-all Show documentation
A library jar that provides APIs for Applications written for the Google Android Platform.
/*
* 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 android.annotation.IntDef;
import android.annotation.NonNull;
import android.os.Parcel;
import android.os.Parcelable;
import com.android.internal.util.BitUtils;
import com.android.internal.util.Preconditions;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Random;
/**
* Representation of a MAC address.
*
* This class only supports 48 bits long addresses and does not support 64 bits long addresses.
* Instances of this class are immutable.
*/
public final class MacAddress implements Parcelable {
private static final int ETHER_ADDR_LEN = 6;
private static final byte[] ETHER_ADDR_BROADCAST = addr(0xff, 0xff, 0xff, 0xff, 0xff, 0xff);
/**
* The MacAddress representing the unique broadcast MAC address.
*/
public static final MacAddress BROADCAST_ADDRESS = MacAddress.fromBytes(ETHER_ADDR_BROADCAST);
/**
* The MacAddress zero MAC address.
* @hide
*/
public static final MacAddress ALL_ZEROS_ADDRESS = new MacAddress(0);
/** @hide */
@Retention(RetentionPolicy.SOURCE)
@IntDef(prefix = { "TYPE_" }, value = {
TYPE_UNKNOWN,
TYPE_UNICAST,
TYPE_MULTICAST,
TYPE_BROADCAST,
})
public @interface MacAddressType { }
/** @hide Indicates a MAC address of unknown type. */
public static final int TYPE_UNKNOWN = 0;
/** Indicates a MAC address is a unicast address. */
public static final int TYPE_UNICAST = 1;
/** Indicates a MAC address is a multicast address. */
public static final int TYPE_MULTICAST = 2;
/** Indicates a MAC address is the broadcast address. */
public static final int TYPE_BROADCAST = 3;
private static final long VALID_LONG_MASK = (1L << 48) - 1;
private static final long LOCALLY_ASSIGNED_MASK = MacAddress.fromString("2:0:0:0:0:0").mAddr;
private static final long MULTICAST_MASK = MacAddress.fromString("1:0:0:0:0:0").mAddr;
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");
// 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
// MAC address are encoded in the 6 least significant bytes of the long, where the first
// byte of the array is mapped to the 3rd highest logical byte of the long, the second
// byte of the array is mapped to the 4th highest logical byte of the long, and so on.
private final long mAddr;
private MacAddress(long addr) {
mAddr = (VALID_LONG_MASK & addr);
}
/**
* Returns the type of this address.
*
* @return the int constant representing the MAC address type of this MacAddress.
*/
public @MacAddressType int getAddressType() {
if (equals(BROADCAST_ADDRESS)) {
return TYPE_BROADCAST;
}
if (isMulticastAddress()) {
return TYPE_MULTICAST;
}
return TYPE_UNICAST;
}
/**
* @return true if this MacAddress is a multicast address.
* @hide
*/
public boolean isMulticastAddress() {
return (mAddr & MULTICAST_MASK) != 0;
}
/**
* @return true if this MacAddress is a locally assigned address.
*/
public boolean isLocallyAssigned() {
return (mAddr & LOCALLY_ASSIGNED_MASK) != 0;
}
/**
* @return a byte array representation of this MacAddress.
*/
public @NonNull byte[] toByteArray() {
return byteAddrFromLongAddr(mAddr);
}
@Override
public @NonNull String toString() {
return stringAddrFromLongAddr(mAddr);
}
/**
* @return a String representation of the OUI part of this MacAddress made of 3 hexadecimal
* numbers in [0,ff] joined by ':' characters.
*/
public @NonNull String toOuiString() {
return String.format(
"%02x:%02x:%02x", (mAddr >> 40) & 0xff, (mAddr >> 32) & 0xff, (mAddr >> 24) & 0xff);
}
@Override
public int hashCode() {
return (int) ((mAddr >> 32) ^ mAddr);
}
@Override
public boolean equals(Object o) {
return (o instanceof MacAddress) && ((MacAddress) o).mAddr == mAddr;
}
@Override
public void writeToParcel(Parcel out, int flags) {
out.writeLong(mAddr);
}
@Override
public int describeContents() {
return 0;
}
public static final Parcelable.Creator CREATOR =
new Parcelable.Creator() {
public MacAddress createFromParcel(Parcel in) {
return new MacAddress(in.readLong());
}
public MacAddress[] newArray(int size) {
return new MacAddress[size];
}
};
/**
* Returns true if the given byte array is an valid MAC address.
* A valid byte array representation for a MacAddress is a non-null array of length 6.
*
* @param addr a byte array.
* @return true if the given byte array is not null and has the length of a MAC address.
*
* @hide
*/
public static boolean isMacAddress(byte[] addr) {
return addr != null && addr.length == ETHER_ADDR_LEN;
}
/**
* Returns the MAC address type of the MAC address represented by the given byte array,
* or null if the given byte array does not represent a MAC address.
* A valid byte array representation for a MacAddress is a non-null array of length 6.
*
* @param addr a byte array representing a MAC address.
* @return the int constant representing the MAC address type of the MAC address represented
* by the given byte array, or type UNKNOWN if the byte array is not a valid MAC address.
*
* @hide
*/
public static int macAddressType(byte[] addr) {
if (!isMacAddress(addr)) {
return TYPE_UNKNOWN;
}
return MacAddress.fromBytes(addr).getAddressType();
}
/**
* Converts a String representation of a MAC address to a byte array representation.
* A valid String representation for a MacAddress is a series of 6 values in the
* range [0,ff] printed in hexadecimal and joined by ':' characters.
*
* @param addr a String representation of a MAC address.
* @return the byte representation of the MAC address.
* @throws IllegalArgumentException if the given String is not a valid representation.
*
* @hide
*/
public static @NonNull byte[] byteAddrFromStringAddr(String addr) {
Preconditions.checkNotNull(addr);
String[] parts = addr.split(":");
if (parts.length != ETHER_ADDR_LEN) {
throw new IllegalArgumentException(addr + " was not a valid MAC address");
}
byte[] bytes = new byte[ETHER_ADDR_LEN];
for (int i = 0; i < ETHER_ADDR_LEN; i++) {
int x = Integer.valueOf(parts[i], 16);
if (x < 0 || 0xff < x) {
throw new IllegalArgumentException(addr + "was not a valid MAC address");
}
bytes[i] = (byte) x;
}
return bytes;
}
/**
* Converts a byte array representation of a MAC address to a String representation made
* of 6 hexadecimal numbers in [0,ff] joined by ':' characters.
* A valid byte array representation for a MacAddress is a non-null array of length 6.
*
* @param addr a byte array representation of a MAC address.
* @return the String representation of the MAC address.
* @throws IllegalArgumentException if the given byte array is not a valid representation.
*
* @hide
*/
public static @NonNull String stringAddrFromByteAddr(byte[] addr) {
if (!isMacAddress(addr)) {
return null;
}
return String.format("%02x:%02x:%02x:%02x:%02x:%02x",
addr[0], addr[1], addr[2], addr[3], addr[4], addr[5]);
}
private static byte[] byteAddrFromLongAddr(long addr) {
byte[] bytes = new byte[ETHER_ADDR_LEN];
int index = ETHER_ADDR_LEN;
while (index-- > 0) {
bytes[index] = (byte) addr;
addr = addr >> 8;
}
return bytes;
}
private static long longAddrFromByteAddr(byte[] addr) {
Preconditions.checkNotNull(addr);
if (!isMacAddress(addr)) {
throw new IllegalArgumentException(
Arrays.toString(addr) + " was not a valid MAC address");
}
long longAddr = 0;
for (byte b : addr) {
longAddr = (longAddr << 8) + BitUtils.uint8(b);
}
return longAddr;
}
// Internal conversion function equivalent to longAddrFromByteAddr(byteAddrFromStringAddr(addr))
// that avoids the allocation of an intermediary byte[].
private static long longAddrFromStringAddr(String addr) {
Preconditions.checkNotNull(addr);
String[] parts = addr.split(":");
if (parts.length != ETHER_ADDR_LEN) {
throw new IllegalArgumentException(addr + " was not a valid MAC address");
}
long longAddr = 0;
for (int i = 0; i < parts.length; i++) {
int x = Integer.valueOf(parts[i], 16);
if (x < 0 || 0xff < x) {
throw new IllegalArgumentException(addr + "was not a valid MAC address");
}
longAddr = x + (longAddr << 8);
}
return longAddr;
}
// Internal conversion function equivalent to stringAddrFromByteAddr(byteAddrFromLongAddr(addr))
// that avoids the allocation of an intermediary byte[].
private static @NonNull String stringAddrFromLongAddr(long addr) {
return String.format("%02x:%02x:%02x:%02x:%02x:%02x",
(addr >> 40) & 0xff,
(addr >> 32) & 0xff,
(addr >> 24) & 0xff,
(addr >> 16) & 0xff,
(addr >> 8) & 0xff,
addr & 0xff);
}
/**
* Creates a MacAddress from the given String representation. A valid String representation
* for a MacAddress is a series of 6 values in the range [0,ff] printed in hexadecimal
* and joined by ':' characters.
*
* @param addr a String representation of a MAC address.
* @return the MacAddress corresponding to the given String representation.
* @throws IllegalArgumentException if the given String is not a valid representation.
*/
public static @NonNull MacAddress fromString(@NonNull String addr) {
return new MacAddress(longAddrFromStringAddr(addr));
}
/**
* Creates a MacAddress from the given byte array representation.
* A valid byte array representation for a MacAddress is a non-null array of length 6.
*
* @param addr a byte array representation of a MAC address.
* @return the MacAddress corresponding to the given byte array representation.
* @throws IllegalArgumentException if the given byte array is not a valid representation.
*/
public static @NonNull MacAddress fromBytes(@NonNull byte[] addr) {
return new MacAddress(longAddrFromByteAddr(addr));
}
/**
* Returns a generated MAC address whose 24 least significant bits constituting the
* NIC part of the address are randomly selected and has Google OUI base.
*
* The locally assigned bit is always set to 1. The multicast bit is always set to 0.
*
* @return a random locally assigned, unicast MacAddress with Google OUI.
*
* @hide
*/
public static @NonNull MacAddress createRandomUnicastAddressWithGoogleBase() {
return createRandomUnicastAddress(BASE_GOOGLE_MAC, new SecureRandom());
}
/**
* Returns a generated MAC address whose 46 bits, excluding the locally assigned bit and the
* unicast bit, are randomly selected.
*
* The locally assigned bit is always set to 1. The multicast bit is always set to 0.
*
* @return a random locally assigned, unicast MacAddress.
*
* @hide
*/
public static @NonNull MacAddress createRandomUnicastAddress() {
SecureRandom r = new SecureRandom();
long addr = r.nextLong() & VALID_LONG_MASK;
addr |= LOCALLY_ASSIGNED_MASK;
addr &= ~MULTICAST_MASK;
return new MacAddress(addr);
}
/**
* Returns a randomly generated MAC address using the given Random object and the same
* OUI values as the given MacAddress.
*
* 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.
* @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());
addr |= LOCALLY_ASSIGNED_MASK;
addr &= ~MULTICAST_MASK;
return new MacAddress(addr);
}
// Convenience function for working around the lack of byte literals.
private static byte[] addr(int... in) {
if (in.length != ETHER_ADDR_LEN) {
throw new IllegalArgumentException(Arrays.toString(in)
+ " was not an array with length equal to " + ETHER_ADDR_LEN);
}
byte[] out = new byte[ETHER_ADDR_LEN];
for (int i = 0; i < ETHER_ADDR_LEN; i++) {
out[i] = (byte) in[i];
}
return out;
}
}