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/*
* Copyright (C) 2021 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.
*/
#include "InterceptorRelay.h"
#include <android-base/logging.h>
#include <libnl++/printer.h>
#include <poll.h>
#include <chrono>
#include "util.h"
namespace android::nlinterceptor {
using namespace std::chrono_literals;
static constexpr std::chrono::milliseconds kPollTimeout = 300ms;
static constexpr bool kSuperVerbose = true;
InterceptorRelay::InterceptorRelay(uint32_t nlFamily, uint32_t clientNlPid,
const std::string& clientName)
: mClientName(clientName),
mNlSocket(std::make_optional<nl::Socket>(nlFamily, 0, 0)),
mClientNlPid(clientNlPid) {}
InterceptorRelay::~InterceptorRelay() {
mRunning = false;
if (mRelayThread.joinable()) mRelayThread.join();
}
uint32_t InterceptorRelay::getPid() {
auto pidMaybe = mNlSocket->getPid();
CHECK(pidMaybe.has_value()) << "Failed to get pid of nl::Socket!";
return *pidMaybe;
}
void InterceptorRelay::relayMessages() {
pollfd fds[] = {
mNlSocket->preparePoll(POLLIN),
};
while (mRunning) {
if (poll(fds, countof(fds), kPollTimeout.count()) < 0) {
PLOG(FATAL) << "poll failed";
return;
}
const auto nlsockEvents = fds[0].revents;
if (isSocketBad(nlsockEvents)) {
LOG(ERROR) << "Netlink socket is bad";
mRunning = false;
return;
}
if (!isSocketReadable(nlsockEvents)) continue;
const auto [msgMaybe, sa] = mNlSocket->receiveFrom();
if (!msgMaybe.has_value()) {
LOG(ERROR) << "Failed to receive Netlink data!";
mRunning = false;
return;
}
const auto msg = *msgMaybe;
if (!msg.firstOk()) {
LOG(ERROR) << "Netlink packet is malformed!";
// Test messages might be empty, this isn't fatal.
continue;
}
if constexpr (kSuperVerbose) {
LOG(VERBOSE) << "[" << mClientName
<< "] nlMsg: " << nl::toString(msg, NETLINK_GENERIC);
}
uint32_t destinationPid = 0;
if (sa.nl_pid == 0) {
destinationPid = mClientNlPid;
}
if (!mNlSocket->send(msg, destinationPid)) {
LOG(ERROR) << "Failed to send Netlink message!";
mRunning = false;
return;
}
}
LOG(VERBOSE) << "[" << mClientName << "] Exiting relay thread!";
}
bool InterceptorRelay::start() {
if (mRunning) {
LOG(ERROR)
<< "Can't relay messages: InterceptorRelay is already running!";
return false;
}
if (mRelayThread.joinable()) {
LOG(ERROR) << "relay thread is already running!";
return false;
}
if (!mNlSocket.has_value()) {
LOG(ERROR) << "Netlink socket not initialized!";
return false;
}
mRunning = true;
mRelayThread = std::thread(&InterceptorRelay::relayMessages, this);
LOG(VERBOSE) << "Relay threads initialized";
return true;
}
bool InterceptorRelay::subscribeGroup(uint32_t nlGroup) {
return mNlSocket->addMembership(nlGroup);
}
bool InterceptorRelay::unsubscribeGroup(uint32_t nlGroup) {
return mNlSocket->dropMembership(nlGroup);
}
} // namespace android::nlinterceptor
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