services/core/java/com/android/server/CommonTimeManagementService.java - platform/frameworks/base - Git at Google

 /*
  * Copyright (C) 2012 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 java.io.FileDescriptor;
 import java.io.PrintWriter;

 import android.content.BroadcastReceiver;
 import android.content.Context;
 import android.content.Intent;
 import android.content.IntentFilter;
 import android.content.pm.PackageManager;
 import android.net.ConnectivityManager;
 import android.net.INetworkManagementEventObserver;
 import android.net.InterfaceConfiguration;
 import android.os.Binder;
 import android.os.CommonTimeConfig;
 import android.os.Handler;
 import android.os.IBinder;
 import android.os.INetworkManagementService;
 import android.os.RemoteException;
 import android.os.ServiceManager;
 import android.os.SystemProperties;
 import android.util.Log;

 import com.android.server.net.BaseNetworkObserver;

 /**
  * @hide
  * <p>CommonTimeManagementService manages the configuration of the native Common Time service,
  * reconfiguring the native service as appropriate in response to changes in network configuration.
  */
 class CommonTimeManagementService extends Binder {
     /*
      * Constants and globals.
      */
     private static final String TAG = CommonTimeManagementService.class.getSimpleName();
     private static final int NATIVE_SERVICE_RECONNECT_TIMEOUT = 5000;
     private static final String AUTO_DISABLE_PROP = "ro.common_time.auto_disable";
     private static final String ALLOW_WIFI_PROP = "ro.common_time.allow_wifi";
     private static final String SERVER_PRIO_PROP = "ro.common_time.server_prio";
     private static final String NO_INTERFACE_TIMEOUT_PROP = "ro.common_time.no_iface_timeout";
     private static final boolean AUTO_DISABLE;
     private static final boolean ALLOW_WIFI;
     private static final byte BASE_SERVER_PRIO;
     private static final int NO_INTERFACE_TIMEOUT;
     private static final InterfaceScoreRule[] IFACE_SCORE_RULES;

     static {
         int tmp;
         AUTO_DISABLE         = (0 != SystemProperties.getInt(AUTO_DISABLE_PROP, 1));
         ALLOW_WIFI           = (0 != SystemProperties.getInt(ALLOW_WIFI_PROP, 0));
         tmp                  = SystemProperties.getInt(SERVER_PRIO_PROP, 1);
         NO_INTERFACE_TIMEOUT = SystemProperties.getInt(NO_INTERFACE_TIMEOUT_PROP, 60000);

         if (tmp < 1)
             BASE_SERVER_PRIO = 1;
         else
         if (tmp > 30)
             BASE_SERVER_PRIO = 30;
         else
             BASE_SERVER_PRIO = (byte)tmp;

         if (ALLOW_WIFI) {
             IFACE_SCORE_RULES = new InterfaceScoreRule[] {
                 new InterfaceScoreRule("wlan", (byte)1),
                 new InterfaceScoreRule("eth", (byte)2),
             };
         } else {
             IFACE_SCORE_RULES = new InterfaceScoreRule[] {
                 new InterfaceScoreRule("eth", (byte)2),
             };
         }
     };

     /*
      * Internal state
      */
     private final Context mContext;
     private INetworkManagementService mNetMgr;
     private CommonTimeConfig mCTConfig;
     private String mCurIface;
     private Handler mReconnectHandler = new Handler();
     private Handler mNoInterfaceHandler = new Handler();
     private Object mLock = new Object();
     private boolean mDetectedAtStartup = false;
     private byte mEffectivePrio = BASE_SERVER_PRIO;

     /*
      * Callback handler implementations.
      */
     private INetworkManagementEventObserver mIfaceObserver = new BaseNetworkObserver() {
         public void interfaceStatusChanged(String iface, boolean up) {
             reevaluateServiceState();
         }
         public void interfaceLinkStateChanged(String iface, boolean up) {
             reevaluateServiceState();
         }
         public void interfaceAdded(String iface) {
             reevaluateServiceState();
         }
         public void interfaceRemoved(String iface) {
             reevaluateServiceState();
         }
     };

     private BroadcastReceiver mConnectivityMangerObserver = new BroadcastReceiver() {
         @Override
         public void onReceive(Context context, Intent intent) {
             reevaluateServiceState();
         }
     };

     private CommonTimeConfig.OnServerDiedListener mCTServerDiedListener =
         new CommonTimeConfig.OnServerDiedListener() {
             public void onServerDied() {
                 scheduleTimeConfigReconnect();
             }
         };

     private Runnable mReconnectRunnable = new Runnable() {
         public void run() { connectToTimeConfig(); }
     };

     private Runnable mNoInterfaceRunnable = new Runnable() {
         public void run() { handleNoInterfaceTimeout(); }
     };

     /*
      * Public interface (constructor, systemReady and dump)
      */
     public CommonTimeManagementService(Context context) {
         mContext = context;
     }

     void systemRunning() {
         if (ServiceManager.checkService(CommonTimeConfig.SERVICE_NAME) == null) {
             Log.i(TAG, "No common time service detected on this platform.  " +
                        "Common time services will be unavailable.");
             return;
         }

         mDetectedAtStartup = true;

         IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
         mNetMgr = INetworkManagementService.Stub.asInterface(b);

         // Network manager is running along-side us, so we should never receiver a remote exception
         // while trying to register this observer.
         try {
             mNetMgr.registerObserver(mIfaceObserver);
         }
         catch (RemoteException e) { }

         // Register with the connectivity manager for connectivity changed intents.
         IntentFilter filter = new IntentFilter();
         filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
         mContext.registerReceiver(mConnectivityMangerObserver, filter);

         // Connect to the common time config service and apply the initial configuration.
         connectToTimeConfig();
     }

     @Override
     protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
         if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
                 != PackageManager.PERMISSION_GRANTED) {
             pw.println(String.format(
                         "Permission Denial: can't dump CommonTimeManagement service from from " +
                         "pid=%d, uid=%d", Binder.getCallingPid(), Binder.getCallingUid()));
             return;
         }

         if (!mDetectedAtStartup) {
             pw.println("Native Common Time service was not detected at startup.  " +
                        "Service is unavailable");
             return;
         }

         synchronized (mLock) {
             pw.println("Current Common Time Management Service Config:");
             pw.println(String.format("  Native service     : %s",
                                      (null == mCTConfig) ? "reconnecting"
                                                          : "alive"));
             pw.println(String.format("  Bound interface    : %s",
                                      (null == mCurIface ? "unbound" : mCurIface)));
             pw.println(String.format("  Allow WiFi         : %s", ALLOW_WIFI ? "yes" : "no"));
             pw.println(String.format("  Allow Auto Disable : %s", AUTO_DISABLE ? "yes" : "no"));
             pw.println(String.format("  Server Priority    : %d", mEffectivePrio));
             pw.println(String.format("  No iface timeout   : %d", NO_INTERFACE_TIMEOUT));
         }
     }

     /*
      * Inner helper classes
      */
     private static class InterfaceScoreRule {
         public final String mPrefix;
         public final byte mScore;
         public InterfaceScoreRule(String prefix, byte score) {
             mPrefix = prefix;
             mScore = score;
         }
     };

     /*
      * Internal implementation
      */
     private void cleanupTimeConfig() {
         mReconnectHandler.removeCallbacks(mReconnectRunnable);
         mNoInterfaceHandler.removeCallbacks(mNoInterfaceRunnable);
         if (null != mCTConfig) {
             mCTConfig.release();
             mCTConfig = null;
         }
     }

     private void connectToTimeConfig() {
         // Get access to the common time service configuration interface.  If we catch a remote
         // exception in the process (service crashed or no running for w/e reason), schedule an
         // attempt to reconnect in the future.
         cleanupTimeConfig();
         try {
             synchronized (mLock) {
                 mCTConfig = new CommonTimeConfig();
                 mCTConfig.setServerDiedListener(mCTServerDiedListener);
                 mCurIface = mCTConfig.getInterfaceBinding();
                 mCTConfig.setAutoDisable(AUTO_DISABLE);
                 mCTConfig.setMasterElectionPriority(mEffectivePrio);
             }

             if (NO_INTERFACE_TIMEOUT >= 0)
                 mNoInterfaceHandler.postDelayed(mNoInterfaceRunnable, NO_INTERFACE_TIMEOUT);

             reevaluateServiceState();
         }
         catch (RemoteException e) {
             scheduleTimeConfigReconnect();
         }
     }

     private void scheduleTimeConfigReconnect() {
         cleanupTimeConfig();
         Log.w(TAG, String.format("Native service died, will reconnect in %d mSec",
                                  NATIVE_SERVICE_RECONNECT_TIMEOUT));
         mReconnectHandler.postDelayed(mReconnectRunnable,
                                       NATIVE_SERVICE_RECONNECT_TIMEOUT);
     }

     private void handleNoInterfaceTimeout() {
         if (null != mCTConfig) {
             Log.i(TAG, "Timeout waiting for interface to come up.  " +
                        "Forcing networkless master mode.");
             if (CommonTimeConfig.ERROR_DEAD_OBJECT == mCTConfig.forceNetworklessMasterMode())
                 scheduleTimeConfigReconnect();
         }
     }

     private void reevaluateServiceState() {
         String bindIface = null;
         byte bestScore = -1;
         try {
             // Check to see if this interface is suitable to use for time synchronization.
             //
             // TODO : This selection algorithm needs to be enhanced for use with mobile devices.  In
             // particular, the choice of whether to a wireless interface or not should not be an all
             // or nothing thing controlled by properties.  It would probably be better if the
             // platform had some concept of public wireless networks vs. home or friendly wireless
             // networks (something a user would configure in settings or when a new interface is
             // added).  Then this algorithm could pick only wireless interfaces which were flagged
             // as friendly, and be dormant when on public wireless networks.
             //
             // Another issue which needs to be dealt with is the use of driver supplied interface
             // name to determine the network type.  The fact that the wireless interface on a device
             // is named "wlan0" is just a matter of convention; its not a 100% rule.  For example,
             // there are devices out there where the wireless is name "tiwlan0", not "wlan0".  The
             // internal network management interfaces in Android have all of the information needed
             // to make a proper classification, there is just no way (currently) to fetch an
             // interface's type (available from the ConnectionManager) as well as its address
             // (available from either the java.net interfaces or from the NetworkManagment service).
             // Both can enumerate interfaces, but that is no way to correlate their results (no
             // common shared key; although using the interface name in the connection manager would
             // be a good start).  Until this gets resolved, we resort to substring searching for
             // tags like wlan and eth.
             //
             String ifaceList[] = mNetMgr.listInterfaces();
             if (null != ifaceList) {
                 for (String iface : ifaceList) {

                     byte thisScore = -1;
                     for (InterfaceScoreRule r : IFACE_SCORE_RULES) {
                         if (iface.contains(r.mPrefix)) {
                             thisScore = r.mScore;
                             break;
                         }
                     }

                     if (thisScore <= bestScore)
                         continue;

                     InterfaceConfiguration config = mNetMgr.getInterfaceConfig(iface);
                     if (null == config)
                         continue;

                     if (config.isActive()) {
                         bindIface = iface;
                         bestScore = thisScore;
                     }
                 }
             }
         }
         catch (RemoteException e) {
             // Bad news; we should not be getting remote exceptions from the connectivity manager
             // since it is running in SystemServer along side of us.  It probably does not matter
             // what we do here, but go ahead and unbind the common time service in this case, just
             // so we have some defined behavior.
             bindIface = null;
         }

         boolean doRebind = true;
         synchronized (mLock) {
             if ((null != bindIface) && (null == mCurIface)) {
                 Log.e(TAG, String.format("Binding common time service to %s.", bindIface));
                 mCurIface = bindIface;
             } else
             if ((null == bindIface) && (null != mCurIface)) {
                 Log.e(TAG, "Unbinding common time service.");
                 mCurIface = null;
             } else
             if ((null != bindIface) && (null != mCurIface) && !bindIface.equals(mCurIface)) {
                 Log.e(TAG, String.format("Switching common time service binding from %s to %s.",
                                          mCurIface, bindIface));
                 mCurIface = bindIface;
             } else {
                 doRebind = false;
             }
         }

         if (doRebind && (null != mCTConfig)) {
             byte newPrio = (bestScore > 0)
                          ? (byte)(bestScore * BASE_SERVER_PRIO)
                          : BASE_SERVER_PRIO;
             if (newPrio != mEffectivePrio) {
                 mEffectivePrio = newPrio;
                 mCTConfig.setMasterElectionPriority(mEffectivePrio);
             }

             int res = mCTConfig.setNetworkBinding(mCurIface);
             if (res != CommonTimeConfig.SUCCESS)
                 scheduleTimeConfigReconnect();

             else if (NO_INTERFACE_TIMEOUT >= 0) {
                 mNoInterfaceHandler.removeCallbacks(mNoInterfaceRunnable);
                 if (null == mCurIface)
                     mNoInterfaceHandler.postDelayed(mNoInterfaceRunnable, NO_INTERFACE_TIMEOUT);
             }
         }
     }
 }
	/*
	* Copyright (C) 2012 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 java.io.FileDescriptor;
	import java.io.PrintWriter;

	import android.content.BroadcastReceiver;
	import android.content.Context;
	import android.content.Intent;
	import android.content.IntentFilter;
	import android.content.pm.PackageManager;
	import android.net.ConnectivityManager;
	import android.net.INetworkManagementEventObserver;
	import android.net.InterfaceConfiguration;
	import android.os.Binder;
	import android.os.CommonTimeConfig;
	import android.os.Handler;
	import android.os.IBinder;
	import android.os.INetworkManagementService;
	import android.os.RemoteException;
	import android.os.ServiceManager;
	import android.os.SystemProperties;
	import android.util.Log;

	import com.android.server.net.BaseNetworkObserver;

	/**
	* @hide
	* <p>CommonTimeManagementService manages the configuration of the native Common Time service,
	* reconfiguring the native service as appropriate in response to changes in network configuration.
	*/
	class CommonTimeManagementService extends Binder {
	/*
	* Constants and globals.
	*/
	private static final String TAG = CommonTimeManagementService.class.getSimpleName();
	private static final int NATIVE_SERVICE_RECONNECT_TIMEOUT = 5000;
	private static final String AUTO_DISABLE_PROP = "ro.common_time.auto_disable";
	private static final String ALLOW_WIFI_PROP = "ro.common_time.allow_wifi";
	private static final String SERVER_PRIO_PROP = "ro.common_time.server_prio";
	private static final String NO_INTERFACE_TIMEOUT_PROP = "ro.common_time.no_iface_timeout";
	private static final boolean AUTO_DISABLE;
	private static final boolean ALLOW_WIFI;
	private static final byte BASE_SERVER_PRIO;
	private static final int NO_INTERFACE_TIMEOUT;
	private static final InterfaceScoreRule[] IFACE_SCORE_RULES;

	static {
	int tmp;
	AUTO_DISABLE = (0 != SystemProperties.getInt(AUTO_DISABLE_PROP, 1));
	ALLOW_WIFI = (0 != SystemProperties.getInt(ALLOW_WIFI_PROP, 0));
	tmp = SystemProperties.getInt(SERVER_PRIO_PROP, 1);
	NO_INTERFACE_TIMEOUT = SystemProperties.getInt(NO_INTERFACE_TIMEOUT_PROP, 60000);

	if (tmp < 1)
	BASE_SERVER_PRIO = 1;
	else
	if (tmp > 30)
	BASE_SERVER_PRIO = 30;
	else
	BASE_SERVER_PRIO = (byte)tmp;

	if (ALLOW_WIFI) {
	IFACE_SCORE_RULES = new InterfaceScoreRule[] {
	new InterfaceScoreRule("wlan", (byte)1),
	new InterfaceScoreRule("eth", (byte)2),
	};
	} else {
	IFACE_SCORE_RULES = new InterfaceScoreRule[] {
	new InterfaceScoreRule("eth", (byte)2),
	};
	}
	};

	/*
	* Internal state
	*/
	private final Context mContext;
	private INetworkManagementService mNetMgr;
	private CommonTimeConfig mCTConfig;
	private String mCurIface;
	private Handler mReconnectHandler = new Handler();
	private Handler mNoInterfaceHandler = new Handler();
	private Object mLock = new Object();
	private boolean mDetectedAtStartup = false;
	private byte mEffectivePrio = BASE_SERVER_PRIO;

	/*
	* Callback handler implementations.
	*/
	private INetworkManagementEventObserver mIfaceObserver = new BaseNetworkObserver() {
	public void interfaceStatusChanged(String iface, boolean up) {
	reevaluateServiceState();
	}
	public void interfaceLinkStateChanged(String iface, boolean up) {
	reevaluateServiceState();
	}
	public void interfaceAdded(String iface) {
	reevaluateServiceState();
	}
	public void interfaceRemoved(String iface) {
	reevaluateServiceState();
	}
	};

	private BroadcastReceiver mConnectivityMangerObserver = new BroadcastReceiver() {
	@Override
	public void onReceive(Context context, Intent intent) {
	reevaluateServiceState();
	}
	};

	private CommonTimeConfig.OnServerDiedListener mCTServerDiedListener =
	new CommonTimeConfig.OnServerDiedListener() {
	public void onServerDied() {
	scheduleTimeConfigReconnect();
	}
	};

	private Runnable mReconnectRunnable = new Runnable() {
	public void run() { connectToTimeConfig(); }
	};

	private Runnable mNoInterfaceRunnable = new Runnable() {
	public void run() { handleNoInterfaceTimeout(); }
	};

	/*
	* Public interface (constructor, systemReady and dump)
	*/
	public CommonTimeManagementService(Context context) {
	mContext = context;
	}

	void systemRunning() {
	if (ServiceManager.checkService(CommonTimeConfig.SERVICE_NAME) == null) {
	Log.i(TAG, "No common time service detected on this platform. " +
	"Common time services will be unavailable.");
	return;
	}

	mDetectedAtStartup = true;

	IBinder b = ServiceManager.getService(Context.NETWORKMANAGEMENT_SERVICE);
	mNetMgr = INetworkManagementService.Stub.asInterface(b);

	// Network manager is running along-side us, so we should never receiver a remote exception
	// while trying to register this observer.
	try {
	mNetMgr.registerObserver(mIfaceObserver);
	}
	catch (RemoteException e) { }

	// Register with the connectivity manager for connectivity changed intents.
	IntentFilter filter = new IntentFilter();
	filter.addAction(ConnectivityManager.CONNECTIVITY_ACTION);
	mContext.registerReceiver(mConnectivityMangerObserver, filter);

	// Connect to the common time config service and apply the initial configuration.
	connectToTimeConfig();
	}

	@Override
	protected void dump(FileDescriptor fd, PrintWriter pw, String[] args) {
	if (mContext.checkCallingOrSelfPermission(android.Manifest.permission.DUMP)
	!= PackageManager.PERMISSION_GRANTED) {
	pw.println(String.format(
	"Permission Denial: can't dump CommonTimeManagement service from from " +
	"pid=%d, uid=%d", Binder.getCallingPid(), Binder.getCallingUid()));
	return;
	}

	if (!mDetectedAtStartup) {
	pw.println("Native Common Time service was not detected at startup. " +
	"Service is unavailable");
	return;
	}

	synchronized (mLock) {
	pw.println("Current Common Time Management Service Config:");
	pw.println(String.format(" Native service : %s",
	(null == mCTConfig) ? "reconnecting"
	: "alive"));
	pw.println(String.format(" Bound interface : %s",
	(null == mCurIface ? "unbound" : mCurIface)));
	pw.println(String.format(" Allow WiFi : %s", ALLOW_WIFI ? "yes" : "no"));
	pw.println(String.format(" Allow Auto Disable : %s", AUTO_DISABLE ? "yes" : "no"));
	pw.println(String.format(" Server Priority : %d", mEffectivePrio));
	pw.println(String.format(" No iface timeout : %d", NO_INTERFACE_TIMEOUT));
	}
	}

	/*
	* Inner helper classes
	*/
	private static class InterfaceScoreRule {
	public final String mPrefix;
	public final byte mScore;
	public InterfaceScoreRule(String prefix, byte score) {
	mPrefix = prefix;
	mScore = score;
	}
	};

	/*
	* Internal implementation
	*/
	private void cleanupTimeConfig() {
	mReconnectHandler.removeCallbacks(mReconnectRunnable);
	mNoInterfaceHandler.removeCallbacks(mNoInterfaceRunnable);
	if (null != mCTConfig) {
	mCTConfig.release();
	mCTConfig = null;
	}
	}

	private void connectToTimeConfig() {
	// Get access to the common time service configuration interface. If we catch a remote
	// exception in the process (service crashed or no running for w/e reason), schedule an
	// attempt to reconnect in the future.
	cleanupTimeConfig();
	try {
	synchronized (mLock) {
	mCTConfig = new CommonTimeConfig();
	mCTConfig.setServerDiedListener(mCTServerDiedListener);
	mCurIface = mCTConfig.getInterfaceBinding();
	mCTConfig.setAutoDisable(AUTO_DISABLE);
	mCTConfig.setMasterElectionPriority(mEffectivePrio);
	}

	if (NO_INTERFACE_TIMEOUT >= 0)
	mNoInterfaceHandler.postDelayed(mNoInterfaceRunnable, NO_INTERFACE_TIMEOUT);

	reevaluateServiceState();
	}
	catch (RemoteException e) {
	scheduleTimeConfigReconnect();
	}
	}

	private void scheduleTimeConfigReconnect() {
	cleanupTimeConfig();
	Log.w(TAG, String.format("Native service died, will reconnect in %d mSec",
	NATIVE_SERVICE_RECONNECT_TIMEOUT));
	mReconnectHandler.postDelayed(mReconnectRunnable,
	NATIVE_SERVICE_RECONNECT_TIMEOUT);
	}

	private void handleNoInterfaceTimeout() {
	if (null != mCTConfig) {
	Log.i(TAG, "Timeout waiting for interface to come up. " +
	"Forcing networkless master mode.");
	if (CommonTimeConfig.ERROR_DEAD_OBJECT == mCTConfig.forceNetworklessMasterMode())
	scheduleTimeConfigReconnect();
	}
	}

	private void reevaluateServiceState() {
	String bindIface = null;
	byte bestScore = -1;
	try {
	// Check to see if this interface is suitable to use for time synchronization.
	//
	// TODO : This selection algorithm needs to be enhanced for use with mobile devices. In
	// particular, the choice of whether to a wireless interface or not should not be an all
	// or nothing thing controlled by properties. It would probably be better if the
	// platform had some concept of public wireless networks vs. home or friendly wireless
	// networks (something a user would configure in settings or when a new interface is
	// added). Then this algorithm could pick only wireless interfaces which were flagged
	// as friendly, and be dormant when on public wireless networks.
	//
	// Another issue which needs to be dealt with is the use of driver supplied interface
	// name to determine the network type. The fact that the wireless interface on a device
	// is named "wlan0" is just a matter of convention; its not a 100% rule. For example,
	// there are devices out there where the wireless is name "tiwlan0", not "wlan0". The
	// internal network management interfaces in Android have all of the information needed
	// to make a proper classification, there is just no way (currently) to fetch an
	// interface's type (available from the ConnectionManager) as well as its address
	// (available from either the java.net interfaces or from the NetworkManagment service).
	// Both can enumerate interfaces, but that is no way to correlate their results (no
	// common shared key; although using the interface name in the connection manager would
	// be a good start). Until this gets resolved, we resort to substring searching for
	// tags like wlan and eth.
	//
	String ifaceList[] = mNetMgr.listInterfaces();
	if (null != ifaceList) {
	for (String iface : ifaceList) {

	byte thisScore = -1;
	for (InterfaceScoreRule r : IFACE_SCORE_RULES) {
	if (iface.contains(r.mPrefix)) {
	thisScore = r.mScore;
	break;
	}
	}

	if (thisScore <= bestScore)
	continue;

	InterfaceConfiguration config = mNetMgr.getInterfaceConfig(iface);
	if (null == config)
	continue;

	if (config.isActive()) {
	bindIface = iface;
	bestScore = thisScore;
	}
	}
	}
	}
	catch (RemoteException e) {
	// Bad news; we should not be getting remote exceptions from the connectivity manager
	// since it is running in SystemServer along side of us. It probably does not matter
	// what we do here, but go ahead and unbind the common time service in this case, just
	// so we have some defined behavior.
	bindIface = null;
	}

	boolean doRebind = true;
	synchronized (mLock) {
	if ((null != bindIface) && (null == mCurIface)) {
	Log.e(TAG, String.format("Binding common time service to %s.", bindIface));
	mCurIface = bindIface;
	} else
	if ((null == bindIface) && (null != mCurIface)) {
	Log.e(TAG, "Unbinding common time service.");
	mCurIface = null;
	} else
	if ((null != bindIface) && (null != mCurIface) && !bindIface.equals(mCurIface)) {
	Log.e(TAG, String.format("Switching common time service binding from %s to %s.",
	mCurIface, bindIface));
	mCurIface = bindIface;
	} else {
	doRebind = false;
	}
	}

	if (doRebind && (null != mCTConfig)) {
	byte newPrio = (bestScore > 0)
	? (byte)(bestScore * BASE_SERVER_PRIO)
	: BASE_SERVER_PRIO;
	if (newPrio != mEffectivePrio) {
	mEffectivePrio = newPrio;
	mCTConfig.setMasterElectionPriority(mEffectivePrio);
	}

	int res = mCTConfig.setNetworkBinding(mCurIface);
	if (res != CommonTimeConfig.SUCCESS)
	scheduleTimeConfigReconnect();

	else if (NO_INTERFACE_TIMEOUT >= 0) {
	mNoInterfaceHandler.removeCallbacks(mNoInterfaceRunnable);
	if (null == mCurIface)
	mNoInterfaceHandler.postDelayed(mNoInterfaceRunnable, NO_INTERFACE_TIMEOUT);
	}
	}
	}
	}