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/*
* Copyright (C) 2019 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 "adbwifi/pairing/pairing_server.h"
#include <sys/epoll.h>
#include <sys/eventfd.h>
#include <atomic>
#include <deque>
#include <iomanip>
#include <mutex>
#include <sstream>
#include <thread>
#include <tuple>
#include <unordered_map>
#include <variant>
#include <vector>
#include <adbwifi/pairing/pairing_connection.h>
#include <android-base/logging.h>
#include <android-base/parsenetaddress.h>
#include <android-base/thread_annotations.h>
#include <android-base/unique_fd.h>
#include <cutils/sockets.h>
namespace adbwifi {
namespace pairing {
using android::base::ScopedLockAssertion;
using android::base::unique_fd;
namespace {
// The implimentation has two background threads running: one to handle and
// accept any new pairing connection requests (socket accept), and the other to
// handle connection events (connection started, connection finished).
class PairingServerImpl : public PairingServer {
public:
virtual ~PairingServerImpl();
// All parameters must be non-empty.
explicit PairingServerImpl(const Data& pswd, const PeerInfo& peer_info, const Data& cert,
const Data& priv_key, int port);
// Starts the pairing server. This call is non-blocking. Upon completion,
// if the pairing was successful, then |cb| will be called with the PublicKeyHeader
// containing the info of the trusted peer. Otherwise, |cb| will be
// called with an empty value. Start can only be called once in the lifetime
// of this object.
//
// Returns true if PairingServer was successfully started. Otherwise,
// returns false.
virtual bool start(PairingConnection::ResultCallback cb, void* opaque) override;
private:
// Setup the server socket to accept incoming connections
bool setupServer();
// Force stop the server thread.
void stopServer();
// handles a new pairing client connection
bool handleNewClientConnection(int fd) EXCLUDES(conn_mutex_);
// ======== connection events thread =============
std::mutex conn_mutex_;
std::condition_variable conn_cv_;
using FdVal = int;
using ConnectionPtr = std::unique_ptr<PairingConnection>;
using NewConnectionEvent = std::tuple<unique_fd, ConnectionPtr>;
// <fd, PeerInfo.name, PeerInfo.guid, certificate>
using ConnectionFinishedEvent = std::tuple<FdVal, std::optional<std::string>,
std::optional<std::string>, std::optional<Data>>;
using ConnectionEvent = std::variant<NewConnectionEvent, ConnectionFinishedEvent>;
// Queue for connections to write into. We have a separate queue to read
// from, in order to minimize the time the server thread is blocked.
std::deque<ConnectionEvent> conn_write_queue_ GUARDED_BY(conn_mutex_);
std::deque<ConnectionEvent> conn_read_queue_;
// Map of fds to their PairingConnections currently running.
std::unordered_map<FdVal, ConnectionPtr> connections_;
// Two threads launched when starting the pairing server:
// 1) A server thread that waits for incoming client connections, and
// 2) A connection events thread that synchonizes events from all of the
// clients, since each PairingConnection is running in it's own thread.
void startConnectionEventsThread();
void startServerThread();
std::thread conn_events_thread_;
void connectionEventsWorker();
std::thread server_thread_;
void serverWorker();
bool is_terminate_ GUARDED_BY(conn_mutex_) = false;
enum class State {
Ready,
Running,
Stopped,
};
State state_ = State::Ready;
Data pswd_;
PeerInfo peer_info_;
Data cert_;
Data priv_key_;
int port_ = -1;
PairingConnection::ResultCallback cb_;
void* opaque_ = nullptr;
bool got_valid_pairing_ = false;
static const int kEpollConstSocket = 0;
// Used to break the server thread from epoll_wait
static const int kEpollConstEventFd = 1;
unique_fd epoll_fd_;
unique_fd server_fd_;
unique_fd event_fd_;
}; // PairingServerImpl
PairingServerImpl::PairingServerImpl(const Data& pswd, const PeerInfo& peer_info, const Data& cert,
const Data& priv_key, int port)
: pswd_(pswd), peer_info_(peer_info), cert_(cert), priv_key_(priv_key), port_(port) {
CHECK(!pswd_.empty() && !cert_.empty() && !priv_key_.empty() && port_ > 0);
CHECK('\0' == peer_info.name[kPeerNameLength - 1] &&
'\0' == peer_info.guid[kPeerGuidLength - 1] && strlen(peer_info.name) > 0 &&
strlen(peer_info.guid) > 0);
}
PairingServerImpl::~PairingServerImpl() {
// Since these connections have references to us, let's make sure they
// destruct before us.
if (server_thread_.joinable()) {
stopServer();
server_thread_.join();
}
{
std::lock_guard<std::mutex> lock(conn_mutex_);
is_terminate_ = true;
}
conn_cv_.notify_one();
if (conn_events_thread_.joinable()) {
conn_events_thread_.join();
}
// Notify the cb_ if it hasn't already.
if (!got_valid_pairing_ && cb_ != nullptr) {
cb_(nullptr, nullptr, opaque_);
}
}
bool PairingServerImpl::start(PairingConnection::ResultCallback cb, void* opaque) {
cb_ = cb;
opaque_ = opaque;
if (state_ != State::Ready) {
LOG(ERROR) << "PairingServer already running or stopped";
return false;
}
if (!setupServer()) {
LOG(ERROR) << "Unable to start PairingServer";
state_ = State::Stopped;
return false;
}
state_ = State::Running;
return true;
}
void PairingServerImpl::stopServer() {
if (event_fd_.get() == -1) {
return;
}
uint64_t value = 1;
ssize_t rc = write(event_fd_.get(), &value, sizeof(value));
if (rc == -1) {
// This can happen if the server didn't start.
PLOG(ERROR) << "write to eventfd failed";
} else if (rc != sizeof(value)) {
LOG(FATAL) << "write to event returned short (" << rc << ")";
}
}
bool PairingServerImpl::setupServer() {
epoll_fd_.reset(epoll_create1(EPOLL_CLOEXEC));
if (epoll_fd_ == -1) {
PLOG(ERROR) << "failed to create epoll fd";
return false;
}
event_fd_.reset(eventfd(0, EFD_CLOEXEC | EFD_NONBLOCK));
if (event_fd_ == -1) {
PLOG(ERROR) << "failed to create eventfd";
return false;
}
server_fd_.reset(socket_inaddr_any_server(port_, SOCK_STREAM));
if (server_fd_.get() == -1) {
PLOG(ERROR) << "Failed to start pairing connection server";
return false;
} else if (fcntl(server_fd_.get(), F_SETFD, FD_CLOEXEC) != 0) {
PLOG(ERROR) << "Failed to make server socket cloexec";
return false;
} else if (fcntl(server_fd_.get(), F_SETFD, O_NONBLOCK) != 0) {
PLOG(ERROR) << "Failed to make server socket nonblocking";
return false;
}
startConnectionEventsThread();
startServerThread();
return true;
}
void PairingServerImpl::startServerThread() {
server_thread_ = std::thread([this]() { serverWorker(); });
}
void PairingServerImpl::startConnectionEventsThread() {
conn_events_thread_ = std::thread([this]() { connectionEventsWorker(); });
}
void PairingServerImpl::serverWorker() {
{
struct epoll_event event;
event.events = EPOLLIN;
event.data.u64 = kEpollConstSocket;
CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, server_fd_.get(), &event));
}
{
struct epoll_event event;
event.events = EPOLLIN;
event.data.u64 = kEpollConstEventFd;
CHECK_EQ(0, epoll_ctl(epoll_fd_.get(), EPOLL_CTL_ADD, event_fd_.get(), &event));
}
while (true) {
struct epoll_event events[2];
int rc = TEMP_FAILURE_RETRY(epoll_wait(epoll_fd_.get(), events, 2, -1));
if (rc == -1) {
PLOG(ERROR) << "epoll_wait failed";
return;
} else if (rc == 0) {
LOG(ERROR) << "epoll_wait returned 0";
return;
}
for (int i = 0; i < rc; ++i) {
struct epoll_event& event = events[i];
switch (event.data.u64) {
case kEpollConstSocket:
handleNewClientConnection(server_fd_.get());
break;
case kEpollConstEventFd:
uint64_t dummy;
int rc = TEMP_FAILURE_RETRY(read(event_fd_.get(), &dummy, sizeof(dummy)));
if (rc != sizeof(dummy)) {
PLOG(FATAL) << "failed to read from eventfd (rc=" << rc << ")";
}
return;
}
}
}
}
void PairingServerImpl::connectionEventsWorker() {
for (;;) {
// Transfer the write queue to the read queue.
{
std::unique_lock<std::mutex> lock(conn_mutex_);
ScopedLockAssertion assume_locked(conn_mutex_);
if (is_terminate_) {
// We check |is_terminate_| twice because condition_variable's
// notify() only wakes up a thread if it is in the wait state
// prior to notify(). Furthermore, we aren't holding the mutex
// when processing the events in |conn_read_queue_|.
return;
}
if (conn_write_queue_.empty()) {
// We need to wait for new events, or the termination signal.
conn_cv_.wait(lock, [this]() REQUIRES(conn_mutex_) {
return (is_terminate_ || !conn_write_queue_.empty());
});
}
if (is_terminate_) {
// We're done.
return;
}
// Move all events into the read queue.
conn_read_queue_ = std::move(conn_write_queue_);
conn_write_queue_.clear();
}
// Process all events in the read queue.
while (conn_read_queue_.size() > 0) {
auto& event = conn_read_queue_.front();
if (auto* p = std::get_if<NewConnectionEvent>(&event)) {
// Ignore if we are already at the max number of connections
if (connections_.size() >= internal::kMaxConnections) {
conn_read_queue_.pop_front();
continue;
}
auto [ufd, connection] = std::move(*p);
int fd = ufd.release();
bool started = connection->start(
fd,
[fd](const PeerInfo* peer_info, const Data* cert, void* opaque) {
auto* p = reinterpret_cast<PairingServerImpl*>(opaque);
ConnectionFinishedEvent event;
if (peer_info != nullptr && cert != nullptr) {
event = std::make_tuple(fd, std::string(peer_info->name),
std::string(peer_info->guid), Data(*cert));
} else {
event = std::make_tuple(fd, std::nullopt, std::nullopt,
std::nullopt);
}
{
std::lock_guard<std::mutex> lock(p->conn_mutex_);
p->conn_write_queue_.push_back(std::move(event));
}
p->conn_cv_.notify_one();
},
this);
if (!started) {
LOG(ERROR) << "PairingServer unable to start a PairingConnection fd=" << fd;
ufd.reset(fd);
} else {
connections_[fd] = std::move(connection);
}
} else if (auto* p = std::get_if<ConnectionFinishedEvent>(&event)) {
auto [fd, name, guid, cert] = std::move(*p);
if (name.has_value() && guid.has_value() && cert.has_value() && !name->empty() &&
!guid->empty() && !cert->empty()) {
// Valid pairing. Let's shutdown the server and close any
// pairing connections in progress.
stopServer();
connections_.clear();
CHECK_LE(name->size(), kPeerNameLength);
CHECK_LE(guid->size(), kPeerGuidLength);
PeerInfo info = {};
strncpy(info.name, name->data(), name->size());
strncpy(info.guid, guid->data(), guid->size());
cb_(&info, &*cert, opaque_);
got_valid_pairing_ = true;
return;
}
// Invalid pairing. Close the invalid connection.
if (connections_.find(fd) != connections_.end()) {
connections_.erase(fd);
}
}
conn_read_queue_.pop_front();
}
}
}
bool PairingServerImpl::handleNewClientConnection(int fd) {
unique_fd ufd(TEMP_FAILURE_RETRY(accept4(fd, nullptr, nullptr, SOCK_CLOEXEC)));
if (ufd == -1) {
PLOG(WARNING) << "adb_socket_accept failed fd=" << fd;
return false;
}
auto connection = PairingConnection::create(PairingConnection::Role::Server, pswd_, peer_info_,
cert_, priv_key_);
if (connection == nullptr) {
LOG(ERROR) << "PairingServer unable to create a PairingConnection fd=" << fd;
return false;
}
// send the new connection to the connection thread for further processing
NewConnectionEvent event = std::make_tuple(std::move(ufd), std::move(connection));
{
std::lock_guard<std::mutex> lock(conn_mutex_);
conn_write_queue_.push_back(std::move(event));
}
conn_cv_.notify_one();
return true;
}
} // namespace
// static
std::unique_ptr<PairingServer> PairingServer::create(const Data& pswd, const PeerInfo& peer_info,
const Data& cert, const Data& priv_key,
int port) {
if (pswd.empty() || cert.empty() || priv_key.empty() || port <= 0) {
return nullptr;
}
// Make sure peer_info has a non-empty, null-terminated string for guid and
// name.
if ('\0' != peer_info.name[kPeerNameLength - 1] ||
'\0' != peer_info.guid[kPeerGuidLength - 1] || strlen(peer_info.name) == 0 ||
strlen(peer_info.guid) == 0) {
LOG(ERROR) << "The GUID/short name fields are empty or not null-terminated";
return nullptr;
}
if (port != kDefaultPairingPort) {
LOG(WARNING) << "Starting server with non-default pairing port=" << port;
}
return std::unique_ptr<PairingServer>(
new PairingServerImpl(pswd, peer_info, cert, priv_key, port));
}
} // namespace pairing
} // namespace adbwifi