Add DhcpLeaseRepository

/*

 * Copyright (C) 2018 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.dhcp;

import android.annotation.NonNull;

import android.annotation.Nullable;

import android.net.MacAddress;

import android.os.SystemClock;

import android.text.TextUtils;

import com.android.internal.util.HexDump;

import java.net.Inet4Address;

import java.util.Arrays;

import java.util.Objects;

/**

 * An IPv4 address assignment done through DHCPv4.

 * @hide

 */

public class DhcpLease {

    public static final long EXPIRATION_NEVER = Long.MAX_VALUE;

    public static final String HOSTNAME_NONE = null;

    @Nullable

    private final byte[] mClientId;

    @NonNull

    private final MacAddress mHwAddr;

    @NonNull

    private final Inet4Address mNetAddr;

    /**

     * Expiration time for the lease, to compare with {@link SystemClock#elapsedRealtime()}.

     */

    private final long mExpTime;

    @Nullable

    private final String mHostname;

    public DhcpLease(@Nullable byte[] clientId, @NonNull MacAddress hwAddr,

            @NonNull Inet4Address netAddr, long expTime, @Nullable String hostname) {

        mClientId = (clientId == null ? null : Arrays.copyOf(clientId, clientId.length));

        mHwAddr = hwAddr;

        mNetAddr = netAddr;

        mExpTime = expTime;

        mHostname = hostname;

    }

    @Nullable

    public byte[] getClientId() {

        if (mClientId == null) {

            return null;

        }

        return Arrays.copyOf(mClientId, mClientId.length);

    }

    @NonNull

    public MacAddress getHwAddr() {

        return mHwAddr;

    }

    @Nullable

    public String getHostname() {

        return mHostname;

    }

    @NonNull

    public Inet4Address getNetAddr() {

        return mNetAddr;

    }

    public long getExpTime() {

        return mExpTime;

    }

    /**

     * Push back the expiration time of this lease. If the provided time is sooner than the original

     * expiration time, the lease time will not be updated.

     *

     * <p>The lease hostname is updated with the provided one if set.

     * @return A {@link DhcpLease} with expiration time set to max(expTime, currentExpTime)

     */

    public DhcpLease renewedLease(long expTime, @Nullable String hostname) {

        return new DhcpLease(mClientId, mHwAddr, mNetAddr, Math.max(expTime, mExpTime),

                (hostname == null ? mHostname : hostname));

    }

    public boolean matchesClient(@Nullable byte[] clientId, @NonNull MacAddress hwAddr) {

        if (mClientId != null) {

            return Arrays.equals(mClientId, clientId);

        } else {

            return clientId == null && mHwAddr.equals(hwAddr);

        }

    }

    @Override

    public boolean equals(Object obj) {

        if (!(obj instanceof DhcpLease)) {

            return false;

        }

        final DhcpLease other = (DhcpLease)obj;

        return Arrays.equals(mClientId, other.mClientId)

                && mHwAddr.equals(other.mHwAddr)

                && mNetAddr.equals(other.mNetAddr)

                && mExpTime == other.mExpTime

                && TextUtils.equals(mHostname, other.mHostname);

    }

    @Override

    public int hashCode() {

        return Objects.hash(mClientId, mHwAddr, mNetAddr, mHostname, mExpTime);

    }

    static String clientIdToString(byte[] bytes) {

        if (bytes == null) {

            return "null";

        }

        return HexDump.toHexString(bytes);

    }

    @Override

    public String toString() {

        return String.format("clientId: %s, hwAddr: %s, netAddr: %s, expTime: %d, hostname: %s",

                clientIdToString(mClientId), mHwAddr.toString(), mNetAddr, mExpTime, mHostname);

    }

}