/*
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* Copyright (C) 2018 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#define LOG_TAG "ResolverEventReporter"
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#include "ResolverEventReporter.h"
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#include <android-base/logging.h>
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#include <android/binder_manager.h>
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using aidl::android::net::metrics::INetdEventListener;
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ResolverEventReporter& ResolverEventReporter::getInstance() {
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// It should be initialized only once.
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static ResolverEventReporter instance;
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// Add framework metrics listener. Because the binder service "netd_listener" may be launched
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// later than Netd, try to get binder handler in every instance query if any. The framework
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// metrics listener should be added only once if it has been already added successfully.
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instance.addDefaultListener();
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return instance;
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}
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ResolverEventReporter::ListenerSet ResolverEventReporter::getListeners() const {
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return getListenersImpl();
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}
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int ResolverEventReporter::addListener(const std::shared_ptr<INetdEventListener>& listener) {
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return addListenerImpl(listener);
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}
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// TODO: Consider registering metrics listener from framework and remove this function.
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// Currently, the framework listener "netd_listener" is shared by netd and libnetd_resolv.
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// Consider breaking it into two listeners. Once it has done, may let framework register
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// the listener proactively.
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void ResolverEventReporter::addDefaultListener() {
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std::lock_guard lock(mMutex);
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static bool added = false;
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if (added) return;
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// Use the non-blocking call AServiceManager_checkService in order not to delay DNS
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// lookup threads when the netd_listener service is not ready.
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ndk::SpAIBinder binder = ndk::SpAIBinder(AServiceManager_checkService("netd_listener"));
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std::shared_ptr<INetdEventListener> listener = INetdEventListener::fromBinder(binder);
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if (listener == nullptr) return;
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if (!addListenerImplLocked(listener)) added = true;
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}
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void ResolverEventReporter::handleBinderDied(const void* who) {
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std::lock_guard lock(mMutex);
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// Use the raw binder pointer address to be the identification of dead binder. Treat "who"
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// which passes the raw address of dead binder as an identification only.
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auto found = std::find_if(mListeners.begin(), mListeners.end(),
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[=](const auto& it) { return static_cast<void*>(it.get()) == who; });
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if (found != mListeners.end()) mListeners.erase(found);
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}
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ResolverEventReporter::ListenerSet ResolverEventReporter::getListenersImpl() const {
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std::lock_guard lock(mMutex);
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return mListeners;
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}
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int ResolverEventReporter::addListenerImpl(const std::shared_ptr<INetdEventListener>& listener) {
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std::lock_guard lock(mMutex);
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return addListenerImplLocked(listener);
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}
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int ResolverEventReporter::addListenerImplLocked(
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const std::shared_ptr<INetdEventListener>& listener) {
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if (listener == nullptr) {
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LOG(ERROR) << "The listener should not be null";
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return -EINVAL;
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}
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// TODO: Perhaps ignore the listener which comes from the same binder.
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const auto& it = mListeners.find(listener);
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if (it != mListeners.end()) {
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LOG(WARNING) << "The listener was already subscribed";
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return -EEXIST;
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}
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static AIBinder_DeathRecipient* deathRecipient = nullptr;
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if (deathRecipient == nullptr) {
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// The AIBinder_DeathRecipient object is used to manage all death recipients for multiple
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// binder objects. It doesn't released because there should have at least one binder object
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// from framework.
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// TODO: Considering to remove death recipient for the binder object from framework because
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// it doesn't need death recipient actually.
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deathRecipient = AIBinder_DeathRecipient_new([](void* cookie) {
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ResolverEventReporter::getInstance().handleBinderDied(cookie);
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});
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}
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// Pass the raw binder pointer address to be the cookie of the death recipient. While the death
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// notification is fired, the cookie is used for identifying which binder was died. Because
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// the NDK binder doesn't pass dead binder pointer to binder death handler, the binder death
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// handler can't know who was died via wp<IBinder>. The reason for wp<IBinder> is not passed
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// is that NDK binder can't transform a wp<IBinder> to a wp<AIBinder> in some cases.
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// See more information in b/128712772.
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auto binder = listener->asBinder().get();
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auto cookie = static_cast<void*>(listener.get()); // Used for dead binder identification.
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binder_status_t status = AIBinder_linkToDeath(binder, deathRecipient, cookie);
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if (STATUS_OK != status) {
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LOG(ERROR) << "Failed to register death notification for INetdEventListener";
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return -EAGAIN;
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}
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mListeners.insert(listener);
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return 0;
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}
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