1 /*
2 * Copyright (C) 2018 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 #define LOG_TAG "resolv"
17
18 #include "ResolverEventReporter.h"
19
20 #include <android-base/logging.h>
21 #include <android/binder_manager.h>
22
23 using aidl::android::net::metrics::INetdEventListener;
24
getInstance()25 ResolverEventReporter& ResolverEventReporter::getInstance() {
26 // It should be initialized only once.
27 static ResolverEventReporter instance;
28
29 // Add framework metrics listener. Because the binder service "netd_listener" may be launched
30 // later than Netd, try to get binder handler in every instance query if any. The framework
31 // metrics listener should be added only once if it has been already added successfully.
32 instance.addDefaultListener();
33
34 return instance;
35 }
36
getListeners() const37 ResolverEventReporter::ListenerSet ResolverEventReporter::getListeners() const {
38 return getListenersImpl();
39 }
40
addListener(const std::shared_ptr<INetdEventListener> & listener)41 int ResolverEventReporter::addListener(const std::shared_ptr<INetdEventListener>& listener) {
42 return addListenerImpl(listener);
43 }
44
45 // TODO: Consider registering metrics listener from framework and remove this function.
46 // Currently, the framework listener "netd_listener" is shared by netd and libnetd_resolv.
47 // Consider breaking it into two listeners. Once it has done, may let framework register
48 // the listener proactively.
addDefaultListener()49 void ResolverEventReporter::addDefaultListener() {
50 std::lock_guard lock(mMutex);
51
52 static bool added = false;
53 if (added) return;
54
55 // Use the non-blocking call AServiceManager_checkService in order not to delay DNS
56 // lookup threads when the netd_listener service is not ready.
57 ndk::SpAIBinder binder = ndk::SpAIBinder(AServiceManager_checkService("netd_listener"));
58 std::shared_ptr<INetdEventListener> listener = INetdEventListener::fromBinder(binder);
59
60 if (listener == nullptr) return;
61
62 if (!addListenerImplLocked(listener)) added = true;
63 }
64
handleBinderDied(const void * who)65 void ResolverEventReporter::handleBinderDied(const void* who) {
66 std::lock_guard lock(mMutex);
67
68 // Use the raw binder pointer address to be the identification of dead binder. Treat "who"
69 // which passes the raw address of dead binder as an identification only.
70 auto found = std::find_if(mListeners.begin(), mListeners.end(),
71 [=](const auto& it) { return static_cast<void*>(it.get()) == who; });
72
73 if (found != mListeners.end()) mListeners.erase(found);
74 }
75
getListenersImpl() const76 ResolverEventReporter::ListenerSet ResolverEventReporter::getListenersImpl() const {
77 std::lock_guard lock(mMutex);
78 return mListeners;
79 }
80
addListenerImpl(const std::shared_ptr<INetdEventListener> & listener)81 int ResolverEventReporter::addListenerImpl(const std::shared_ptr<INetdEventListener>& listener) {
82 std::lock_guard lock(mMutex);
83 return addListenerImplLocked(listener);
84 }
85
addListenerImplLocked(const std::shared_ptr<INetdEventListener> & listener)86 int ResolverEventReporter::addListenerImplLocked(
87 const std::shared_ptr<INetdEventListener>& listener) {
88 if (listener == nullptr) {
89 LOG(ERROR) << "The listener should not be null";
90 return -EINVAL;
91 }
92
93 for (const auto& it : mListeners) {
94 if (it->asBinder().get() == listener->asBinder().get()) {
95 LOG(WARNING) << "The listener was already subscribed";
96 return -EEXIST;
97 }
98 }
99
100 static AIBinder_DeathRecipient* deathRecipient = nullptr;
101 if (deathRecipient == nullptr) {
102 // The AIBinder_DeathRecipient object is used to manage all death recipients for multiple
103 // binder objects. It doesn't released because there should have at least one binder object
104 // from framework.
105 // TODO: Considering to remove death recipient for the binder object from framework because
106 // it doesn't need death recipient actually.
107 deathRecipient = AIBinder_DeathRecipient_new([](void* cookie) {
108 ResolverEventReporter::getInstance().handleBinderDied(cookie);
109 });
110 }
111
112 // Pass the raw binder pointer address to be the cookie of the death recipient. While the death
113 // notification is fired, the cookie is used for identifying which binder was died. Because
114 // the NDK binder doesn't pass dead binder pointer to binder death handler, the binder death
115 // handler can't know who was died via wp<IBinder>. The reason for wp<IBinder> is not passed
116 // is that NDK binder can't transform a wp<IBinder> to a wp<AIBinder> in some cases.
117 // See more information in b/128712772.
118 auto binder = listener->asBinder().get();
119 auto cookie = static_cast<void*>(listener.get()); // Used for dead binder identification.
120 binder_status_t status = AIBinder_linkToDeath(binder, deathRecipient, cookie);
121
122 if (STATUS_OK != status) {
123 LOG(ERROR) << "Failed to register death notification for INetdEventListener";
124 return -EAGAIN;
125 }
126
127 mListeners.insert(listener);
128 return 0;
129 }