DhcpStateMachine.java revision 41b35884ff68a62f5fc8f65dcc26342d0889113d 
1/*
2 * Copyright (C) 2011 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package android.net;
18
19import com.android.internal.util.Protocol;
20import com.android.internal.util.HierarchicalState;
21import com.android.internal.util.HierarchicalStateMachine;
22
23import android.app.AlarmManager;
24import android.app.PendingIntent;
25import android.content.BroadcastReceiver;
26import android.content.Context;
27import android.content.Intent;
28import android.content.IntentFilter;
29import android.net.DhcpInfoInternal;
30import android.net.NetworkUtils;
31import android.os.Message;
32import android.os.PowerManager;
33import android.os.SystemClock;
34import android.util.Log;
35
36/**
37 * StateMachine that interacts with the native DHCP client and can talk to
38 * a controller that also needs to be a StateMachine
39 *
40 * The Dhcp state machine provides the following features:
41 * - Wakeup and renewal using the native DHCP client  (which will not renew
42 *   on its own when the device is in suspend state and this can lead to device
43 *   holding IP address beyond expiry)
44 * - A notification right before DHCP request or renewal is started. This
45 *   can be used for any additional setup before DHCP. For example, wifi sets
46 *   BT-Wifi coex settings right before DHCP is initiated
47 *
48 * @hide
49 */
50public class DhcpStateMachine extends HierarchicalStateMachine {
51
52    private static final String TAG = "DhcpStateMachine";
53    private static final boolean DBG = false;
54
55
56    /* A StateMachine that controls the DhcpStateMachine */
57    private HierarchicalStateMachine mController;
58
59    private Context mContext;
60    private BroadcastReceiver mBroadcastReceiver;
61    private AlarmManager mAlarmManager;
62    private PendingIntent mDhcpRenewalIntent;
63    private PowerManager.WakeLock mDhcpRenewWakeLock;
64    private static final String WAKELOCK_TAG = "DHCP";
65
66    private static final int DHCP_RENEW = 0;
67    private static final String ACTION_DHCP_RENEW = "android.net.wifi.DHCP_RENEW";
68
69    //Used for sanity check on setting up renewal
70    private static final int MIN_RENEWAL_TIME_SECS = 5 * 60;  // 5 minutes
71
72    private enum DhcpAction {
73        START,
74        RENEW
75    };
76
77    private String mInterfaceName;
78    private boolean mRegisteredForPreDhcpNotification = false;
79
80    private static final int BASE = Protocol.BASE_DHCP;
81
82    /* Commands from controller to start/stop DHCP */
83    public static final int CMD_START_DHCP                  = BASE + 1;
84    public static final int CMD_STOP_DHCP                   = BASE + 2;
85    public static final int CMD_RENEW_DHCP                  = BASE + 3;
86
87    /* Notification from DHCP state machine prior to DHCP discovery/renewal */
88    public static final int CMD_PRE_DHCP_ACTION             = BASE + 4;
89    /* Notification from DHCP state machine post DHCP discovery/renewal. Indicates
90     * success/failure */
91    public static final int CMD_POST_DHCP_ACTION            = BASE + 5;
92
93    /* Command from controller to indicate DHCP discovery/renewal can continue
94     * after pre DHCP action is complete */
95    public static final int CMD_PRE_DHCP_ACTION_COMPLETE    = BASE + 6;
96
97    /* Message.arg1 arguments to CMD_POST_DHCP notification */
98    public static final int DHCP_SUCCESS = 1;
99    public static final int DHCP_FAILURE = 2;
100
101    private HierarchicalState mDefaultState = new DefaultState();
102    private HierarchicalState mStoppedState = new StoppedState();
103    private HierarchicalState mWaitBeforeStartState = new WaitBeforeStartState();
104    private HierarchicalState mRunningState = new RunningState();
105    private HierarchicalState mWaitBeforeRenewalState = new WaitBeforeRenewalState();
106
107    private DhcpStateMachine(Context context, HierarchicalStateMachine controller, String intf) {
108        super(TAG);
109
110        mContext = context;
111        mController = controller;
112        mInterfaceName = intf;
113
114        mAlarmManager = (AlarmManager)mContext.getSystemService(Context.ALARM_SERVICE);
115        Intent dhcpRenewalIntent = new Intent(ACTION_DHCP_RENEW, null);
116        mDhcpRenewalIntent = PendingIntent.getBroadcast(mContext, DHCP_RENEW, dhcpRenewalIntent, 0);
117
118        PowerManager powerManager = (PowerManager)mContext.getSystemService(Context.POWER_SERVICE);
119        mDhcpRenewWakeLock = powerManager.newWakeLock(PowerManager.PARTIAL_WAKE_LOCK, WAKELOCK_TAG);
120
121        mBroadcastReceiver = new BroadcastReceiver() {
122            @Override
123            public void onReceive(Context context, Intent intent) {
124                //DHCP renew
125                if (DBG) Log.d(TAG, "Sending a DHCP renewal " + this);
126                //acquire a 40s wakelock to finish DHCP renewal
127                mDhcpRenewWakeLock.acquire(40000);
128                sendMessage(CMD_RENEW_DHCP);
129            }
130        };
131        mContext.registerReceiver(mBroadcastReceiver, new IntentFilter(ACTION_DHCP_RENEW));
132
133        addState(mDefaultState);
134            addState(mStoppedState, mDefaultState);
135            addState(mWaitBeforeStartState, mDefaultState);
136            addState(mRunningState, mDefaultState);
137            addState(mWaitBeforeRenewalState, mDefaultState);
138
139        setInitialState(mStoppedState);
140    }
141
142    public static DhcpStateMachine makeDhcpStateMachine(Context context, HierarchicalStateMachine controller,
143            String intf) {
144        DhcpStateMachine dsm = new DhcpStateMachine(context, controller, intf);
145        dsm.start();
146        return dsm;
147    }
148
149    /**
150     * This sends a notification right before DHCP request/renewal so that the
151     * controller can do certain actions before DHCP packets are sent out.
152     * When the controller is ready, it sends a CMD_PRE_DHCP_ACTION_COMPLETE message
153     * to indicate DHCP can continue
154     *
155     * This is used by Wifi at this time for the purpose of doing BT-Wifi coex
156     * handling during Dhcp
157     */
158    public void registerForPreDhcpNotification() {
159        mRegisteredForPreDhcpNotification = true;
160    }
161
162    class DefaultState extends HierarchicalState {
163        @Override
164        public boolean processMessage(Message message) {
165            if (DBG) Log.d(TAG, getName() + message.toString() + "\n");
166            switch (message.what) {
167                case CMD_RENEW_DHCP:
168                    Log.e(TAG, "Error! Failed to handle a DHCP renewal on " + mInterfaceName);
169                    break;
170                case HSM_QUIT_CMD:
171                    mContext.unregisterReceiver(mBroadcastReceiver);
172                    //let parent kill the state machine
173                    return NOT_HANDLED;
174                default:
175                    Log.e(TAG, "Error! unhandled message  " + message);
176                    break;
177            }
178            return HANDLED;
179        }
180    }
181
182
183    class StoppedState extends HierarchicalState {
184        @Override
185        public void enter() {
186            if (DBG) Log.d(TAG, getName() + "\n");
187        }
188
189        @Override
190        public boolean processMessage(Message message) {
191            boolean retValue = HANDLED;
192            if (DBG) Log.d(TAG, getName() + message.toString() + "\n");
193            switch (message.what) {
194                case CMD_START_DHCP:
195                    if (mRegisteredForPreDhcpNotification) {
196                        /* Notify controller before starting DHCP */
197                        mController.sendMessage(CMD_PRE_DHCP_ACTION);
198                        transitionTo(mWaitBeforeStartState);
199                    } else {
200                        if (runDhcp(DhcpAction.START)) {
201                            transitionTo(mRunningState);
202                        }
203                    }
204                    break;
205                case CMD_STOP_DHCP:
206                    //ignore
207                    break;
208                default:
209                    retValue = NOT_HANDLED;
210                    break;
211            }
212            return retValue;
213        }
214    }
215
216    class WaitBeforeStartState extends HierarchicalState {
217        @Override
218        public void enter() {
219            if (DBG) Log.d(TAG, getName() + "\n");
220        }
221
222        @Override
223        public boolean processMessage(Message message) {
224            boolean retValue = HANDLED;
225            if (DBG) Log.d(TAG, getName() + message.toString() + "\n");
226            switch (message.what) {
227                case CMD_PRE_DHCP_ACTION_COMPLETE:
228                    if (runDhcp(DhcpAction.START)) {
229                        transitionTo(mRunningState);
230                    } else {
231                        transitionTo(mStoppedState);
232                    }
233                    break;
234                case CMD_STOP_DHCP:
235                    transitionTo(mStoppedState);
236                    break;
237                case CMD_START_DHCP:
238                    //ignore
239                    break;
240                default:
241                    retValue = NOT_HANDLED;
242                    break;
243            }
244            return retValue;
245        }
246    }
247
248    class RunningState extends HierarchicalState {
249        @Override
250        public void enter() {
251            if (DBG) Log.d(TAG, getName() + "\n");
252        }
253
254        @Override
255        public boolean processMessage(Message message) {
256            boolean retValue = HANDLED;
257            if (DBG) Log.d(TAG, getName() + message.toString() + "\n");
258            switch (message.what) {
259                case CMD_STOP_DHCP:
260                    mAlarmManager.cancel(mDhcpRenewalIntent);
261                    if (!NetworkUtils.stopDhcp(mInterfaceName)) {
262                        Log.e(TAG, "Failed to stop Dhcp on " + mInterfaceName);
263                    }
264                    transitionTo(mStoppedState);
265                    break;
266                case CMD_RENEW_DHCP:
267                    if (mRegisteredForPreDhcpNotification) {
268                        /* Notify controller before starting DHCP */
269                        mController.sendMessage(CMD_PRE_DHCP_ACTION);
270                        transitionTo(mWaitBeforeRenewalState);
271                    } else {
272                        if (!runDhcp(DhcpAction.RENEW)) {
273                            transitionTo(mStoppedState);
274                        }
275                    }
276                    break;
277                case CMD_START_DHCP:
278                    //ignore
279                    break;
280                default:
281                    retValue = NOT_HANDLED;
282            }
283            return retValue;
284        }
285    }
286
287    class WaitBeforeRenewalState extends HierarchicalState {
288        @Override
289        public void enter() {
290            if (DBG) Log.d(TAG, getName() + "\n");
291        }
292
293        @Override
294        public boolean processMessage(Message message) {
295            boolean retValue = HANDLED;
296            if (DBG) Log.d(TAG, getName() + message.toString() + "\n");
297            switch (message.what) {
298                case CMD_STOP_DHCP:
299                    mAlarmManager.cancel(mDhcpRenewalIntent);
300                    if (!NetworkUtils.stopDhcp(mInterfaceName)) {
301                        Log.e(TAG, "Failed to stop Dhcp on " + mInterfaceName);
302                    }
303                    transitionTo(mStoppedState);
304                    break;
305                case CMD_PRE_DHCP_ACTION_COMPLETE:
306                    if (runDhcp(DhcpAction.RENEW)) {
307                       transitionTo(mRunningState);
308                    } else {
309                       transitionTo(mStoppedState);
310                    }
311                    break;
312                case CMD_START_DHCP:
313                    //ignore
314                    break;
315                default:
316                    retValue = NOT_HANDLED;
317                    break;
318            }
319            return retValue;
320        }
321    }
322
323    private boolean runDhcp(DhcpAction dhcpAction) {
324        boolean success = false;
325        DhcpInfoInternal dhcpInfoInternal = new DhcpInfoInternal();
326
327        if (dhcpAction == DhcpAction.START) {
328            Log.d(TAG, "DHCP request on " + mInterfaceName);
329            success = NetworkUtils.runDhcp(mInterfaceName, dhcpInfoInternal);
330        } else if (dhcpAction == DhcpAction.RENEW) {
331            Log.d(TAG, "DHCP renewal on " + mInterfaceName);
332            success = NetworkUtils.runDhcpRenew(mInterfaceName, dhcpInfoInternal);
333        }
334
335        if (success) {
336            Log.d(TAG, "DHCP succeeded on " + mInterfaceName);
337           long leaseDuration = dhcpInfoInternal.leaseDuration; //int to long conversion
338
339           //Sanity check for renewal
340           //TODO: would be good to notify the user that his network configuration is
341           //bad and that the device cannot renew below MIN_RENEWAL_TIME_SECS
342           if (leaseDuration < MIN_RENEWAL_TIME_SECS) {
343               leaseDuration = MIN_RENEWAL_TIME_SECS;
344           }
345           //Do it a bit earlier than half the lease duration time
346           //to beat the native DHCP client and avoid extra packets
347           //48% for one hour lease time = 29 minutes
348           mAlarmManager.set(AlarmManager.ELAPSED_REALTIME_WAKEUP,
349                   SystemClock.elapsedRealtime() +
350                   leaseDuration * 480, //in milliseconds
351                   mDhcpRenewalIntent);
352
353            mController.obtainMessage(CMD_POST_DHCP_ACTION, DHCP_SUCCESS, 0, dhcpInfoInternal)
354                .sendToTarget();
355        } else {
356            Log.d(TAG, "DHCP failed on " + mInterfaceName + ": " +
357                    NetworkUtils.getDhcpError());
358            NetworkUtils.stopDhcp(mInterfaceName);
359            mController.obtainMessage(CMD_POST_DHCP_ACTION, DHCP_FAILURE, 0)
360                .sendToTarget();
361        }
362        return success;
363    }
364}
365