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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 android.net.shared;
import static android.net.RouteInfo.RTN_UNICAST;
import static android.system.OsConstants.EBUSY;
import android.net.INetd;
import android.net.IpPrefix;
import android.net.RouteInfo;
import android.net.TetherConfigParcel;
import android.os.RemoteException;
import android.os.ServiceSpecificException;
import android.os.SystemClock;
import android.util.Log;
import java.util.ArrayList;
import java.util.List;
/**
* Implements common operations on INetd
* @hide
*/
public class NetdUtils {
private static final String TAG = NetdUtils.class.getSimpleName();
/** Start tethering. */
public static void tetherStart(final INetd netd, final boolean usingLegacyDnsProxy,
final String[] dhcpRange) throws RemoteException, ServiceSpecificException {
final TetherConfigParcel config = new TetherConfigParcel();
config.usingLegacyDnsProxy = usingLegacyDnsProxy;
config.dhcpRanges = dhcpRange;
netd.tetherStartWithConfiguration(config);
}
/** Setup interface for tethering. */
public static void tetherInterface(final INetd netd, final String iface, final IpPrefix dest)
throws RemoteException, ServiceSpecificException {
tetherInterface(netd, iface, dest, 20 /* maxAttempts */, 50 /* pollingIntervalMs */);
}
/** Setup interface with configurable retries for tethering. */
public static void tetherInterface(final INetd netd, final String iface, final IpPrefix dest,
int maxAttempts, int pollingIntervalMs)
throws RemoteException, ServiceSpecificException {
netd.tetherInterfaceAdd(iface);
networkAddInterface(netd, iface, maxAttempts, pollingIntervalMs);
List<RouteInfo> routes = new ArrayList<>();
routes.add(new RouteInfo(dest, null, iface, RTN_UNICAST));
RouteUtils.addRoutesToLocalNetwork(netd, iface, routes);
}
/**
* Retry Netd#networkAddInterface for EBUSY error code.
* If the same interface (e.g., wlan0) is in client mode and then switches to tethered mode.
* There can be a race where puts the interface into the local network but interface is still
* in use in netd because the ConnectivityService thread hasn't processed the disconnect yet.
* See b/158269544 for detail.
*/
private static void networkAddInterface(final INetd netd, final String iface,
int maxAttempts, int pollingIntervalMs)
throws ServiceSpecificException, RemoteException {
for (int i = 1; i <= maxAttempts; i++) {
try {
netd.networkAddInterface(INetd.LOCAL_NET_ID, iface);
return;
} catch (ServiceSpecificException e) {
if (e.errorCode == EBUSY && i < maxAttempts) {
SystemClock.sleep(pollingIntervalMs);
continue;
}
Log.e(TAG, "Retry Netd#networkAddInterface failure: " + e);
throw e;
}
}
}
/** Reset interface for tethering. */
public static void untetherInterface(final INetd netd, String iface)
throws RemoteException, ServiceSpecificException {
try {
netd.tetherInterfaceRemove(iface);
} finally {
netd.networkRemoveInterface(INetd.LOCAL_NET_ID, iface);
}
}
}
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