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/*
* Copyright (C) 2022 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 "common/libs/utils/socket2socket_proxy.h"
#include <poll.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <cstring>
#include <functional>
#include <list>
#include <memory>
#include <string>
#include <thread>
#include <utility>
#include <vector>
#include <android-base/logging.h>
namespace cuttlefish {
namespace {
class ProxyPair {
public:
ProxyPair()
: stop_fd_(SharedFD::Event()) {
if (!stop_fd_->IsOpen()) {
LOG(FATAL) << "Failed to open eventfd: " << stop_fd_->StrError();
return;
}
}
ProxyPair(ProxyPair&& other)
: started_(other.started_),
stop_fd_(std::move(other.stop_fd_)),
c2t_running_(other.c2t_running_.load()),
t2c_running_(other.t2c_running_.load()) {
if (other.started_) {
LOG(FATAL) << "ProxyPair cannot be moved after Start() being executed";
}
}
~ProxyPair() {
if (stop_fd_->IsOpen() && stop_fd_->EventfdWrite(1) != 0) {
LOG(ERROR) << "Failed to stop proxy thread: " << stop_fd_->StrError();
}
if (c2t_.joinable()) {
c2t_.join();
}
if (t2c_.joinable()) {
t2c_.join();
}
}
void Start(SharedFD from, SharedFD to) {
if (started_) {
LOG(FATAL) << "ProxyPair cannot be started second time";
}
started_ = true;
c2t_running_ = true;
t2c_running_ = true;
c2t_ = std::thread(&ProxyPair::Forward, this, "c2t", from, to, stop_fd_,
std::ref(c2t_running_));
t2c_ = std::thread(&ProxyPair::Forward, this, "t2c", to, from, stop_fd_,
std::ref(t2c_running_));
}
bool Running() {
return c2t_running_ || t2c_running_;
}
private:
void Forward(const std::string& label, SharedFD from, SharedFD to,
SharedFD stop, std::atomic<bool>& running) {
LOG(DEBUG) << label << ": Proxy thread started. Starting copying data";
auto success = to->CopyAllFrom(*from, &(*stop));
if (!success) {
if (from->GetErrno()) {
LOG(ERROR) << label << ": Error reading: " << from->StrError();
}
if (to->GetErrno()) {
LOG(ERROR) << label << ": Error writing: " << to->StrError();
}
}
to->Shutdown(SHUT_WR);
running = false;
LOG(DEBUG) << label << ": Proxy thread completed";
}
bool started_;
SharedFD stop_fd_;
std::atomic<bool> c2t_running_;
std::atomic<bool> t2c_running_;
std::thread c2t_;
std::thread t2c_;
};
} // namespace
ProxyServer::ProxyServer(SharedFD server, std::function<SharedFD()> clients_factory)
: stop_fd_(SharedFD::Event()) {
if (!stop_fd_->IsOpen()) {
LOG(FATAL) << "Failed to open eventfd: " << stop_fd_->StrError();
return;
}
server_ = std::thread([&, server_fd = std::move(server),
clients_factory = std::move(clients_factory)]() {
constexpr ssize_t SERVER = 0;
constexpr ssize_t STOP = 1;
std::list<ProxyPair> watched;
std::vector<PollSharedFd> server_poll = {
{.fd = server_fd, .events = POLLIN},
{.fd = stop_fd_, .events = POLLIN}
};
while (server_fd->IsOpen()) {
server_poll[SERVER].revents = 0;
server_poll[STOP].revents = 0;
const int poll_result = SharedFD::Poll(server_poll, -1);
if (poll_result < 0) {
LOG(ERROR) << "Failed to poll to wait for incoming connection";
continue;
}
if (server_poll[STOP].revents & POLLIN) {
// Stop fd is available to read, so we received a stop event
// and must stop the thread
break;
}
if (!(server_poll[SERVER].revents & POLLIN)) {
continue;
}
// Server fd is available to read, so we can accept the
// connection without blocking on that
auto client = SharedFD::Accept(*server_fd);
if (!client->IsOpen()) {
LOG(ERROR) << "Failed to accept incoming connection: " << client->StrError();
continue;
}
auto target = clients_factory();
if (target->IsOpen()) {
LOG(DEBUG) << "Launching proxy threads";
watched.push_back(ProxyPair());
watched.back().Start(client, target);
LOG(DEBUG) << "Proxy is launched. Amount of currently tracked proxy pairs: "
<< watched.size();
} else {
LOG(ERROR) << "Cannot connect to the target to setup proxying: " << target->StrError();
}
// Unwatch completed proxy pairs
watched.remove_if([](ProxyPair& proxy) { return !proxy.Running(); });
}
// Making sure all launched proxy pairs are finished by triggering their destructor
LOG(DEBUG) << "Waiting for proxy threads to turn down";
watched.clear();
LOG(DEBUG) << "Proxy threads are successfully turned down";
});
}
void ProxyServer::Join() {
if (server_.joinable()) {
server_.join();
}
}
ProxyServer::~ProxyServer() {
if (stop_fd_->EventfdWrite(1) != 0) {
LOG(ERROR) << "Failed to stop proxy thread: " << stop_fd_->StrError();
}
Join();
}
void Proxy(SharedFD server, std::function<SharedFD()> conn_factory) {
ProxyServer proxy(std::move(server), std::move(conn_factory));
proxy.Join();
}
std::unique_ptr<ProxyServer> ProxyAsync(SharedFD server, std::function<SharedFD()> conn_factory) {
return std::make_unique<ProxyServer>(std::move(server), std::move(conn_factory));
}
} // namespace cuttlefish
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