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/*
* Copyright (C) 2019 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 com.android.server;
import android.annotation.NonNull;
import android.net.ConnectivityManager;
import android.util.SparseBooleanArray;
import com.android.internal.annotations.GuardedBy;
import com.android.internal.annotations.VisibleForTesting;
/**
* Class used to reserve and release net IDs.
*
* <p>Instances of this class are thread-safe.
*/
public class NetIdManager {
// Sequence number for Networks; keep in sync with system/netd/NetworkController.cpp
public static final int MIN_NET_ID = 100; // some reserved marks
// Top IDs reserved by IpSecService
public static final int MAX_NET_ID = ConnectivityManager.getIpSecNetIdRange().getLower() - 1;
@GuardedBy("mNetIdInUse")
private final SparseBooleanArray mNetIdInUse = new SparseBooleanArray();
@GuardedBy("mNetIdInUse")
private int mLastNetId = MIN_NET_ID - 1;
private final int mMaxNetId;
public NetIdManager() {
this(MAX_NET_ID);
}
@VisibleForTesting
NetIdManager(int maxNetId) {
mMaxNetId = maxNetId;
}
/**
* Get the first netId that follows the provided lastId and is available.
*/
private int getNextAvailableNetIdLocked(
int lastId, @NonNull SparseBooleanArray netIdInUse) {
int netId = lastId;
for (int i = MIN_NET_ID; i <= mMaxNetId; i++) {
netId = netId < mMaxNetId ? netId + 1 : MIN_NET_ID;
if (!netIdInUse.get(netId)) {
return netId;
}
}
throw new IllegalStateException("No free netIds");
}
/**
* Reserve a new ID for a network.
*/
public int reserveNetId() {
synchronized (mNetIdInUse) {
mLastNetId = getNextAvailableNetIdLocked(mLastNetId, mNetIdInUse);
// Make sure NetID unused. http://b/16815182
mNetIdInUse.put(mLastNetId, true);
return mLastNetId;
}
}
/**
* Clear a previously reserved ID for a network.
*/
public void releaseNetId(int id) {
synchronized (mNetIdInUse) {
mNetIdInUse.delete(id);
}
}
}
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