1 /*
2  * Copyright (C) 2019 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 
17 package android.ext.services.watchdog;
18 
19 import android.net.ConnectivityManager;
20 import android.net.Network;
21 import android.net.NetworkCapabilities;
22 import android.net.NetworkRequest;
23 import android.service.watchdog.ExplicitHealthCheckService;
24 
25 import androidx.annotation.GuardedBy;
26 
27 /**
28  * Observes the network stack via the ConnectivityManager.
29  */
30 final class NetworkChecker extends ConnectivityManager.NetworkCallback
31         implements ExplicitHealthChecker {
32     private static final String TAG = "NetworkChecker";
33 
34     private final Object mLock = new Object();
35     private final ExplicitHealthCheckService mService;
36     private final String mPackageName;
37     @GuardedBy("mLock")
38     private boolean mIsPending;
39 
NetworkChecker(ExplicitHealthCheckService service, String packageName)40     NetworkChecker(ExplicitHealthCheckService service, String packageName) {
41         mService = service;
42         mPackageName = packageName;
43     }
44 
45     @Override
request()46     public void request() {
47         synchronized (mLock) {
48             if (mIsPending) {
49                 return;
50             }
51             mService.getSystemService(ConnectivityManager.class).registerNetworkCallback(
52                     new NetworkRequest.Builder().build(), this);
53             mIsPending = true;
54         }
55     }
56 
57     @Override
cancel()58     public void cancel() {
59         synchronized (mLock) {
60             if (!mIsPending) {
61                 return;
62             }
63             mService.getSystemService(ConnectivityManager.class).unregisterNetworkCallback(this);
64             mIsPending = false;
65         }
66     }
67 
68     @Override
isPending()69     public boolean isPending() {
70         synchronized (mLock) {
71             return mIsPending;
72         }
73     }
74 
75     @Override
getSupportedPackageName()76     public String getSupportedPackageName() {
77         return mPackageName;
78     }
79 
80     // TODO(b/120598832): Also monitor NetworkCallback#onAvailable to see if we have any
81     // available networks that may be unusable. This could be additional signal to our heuristics
82     @Override
onCapabilitiesChanged(Network network, NetworkCapabilities capabilities)83     public void onCapabilitiesChanged(Network network, NetworkCapabilities capabilities) {
84         synchronized (mLock) {
85             if (mIsPending
86                     && capabilities.hasCapability(NetworkCapabilities.NET_CAPABILITY_VALIDATED)) {
87                 mService.notifyHealthCheckPassed(mPackageName);
88                 cancel();
89             }
90         }
91     }
92 }
93