flipper/xplat/Sonar/SonarWebSocketImpl.cpp

/*
 *  Copyright (c) 2018-present, Facebook, Inc.
 *
 *  This source code is licensed under the MIT license found in the LICENSE
 *  file in the root directory of this source tree.
 *
 */

#include "SonarWebSocketImpl.h"
#include "SonarStep.h"
#include <folly/String.h>
#include <folly/futures/Future.h>
#include <folly/io/async/SSLContext.h>
#include <folly/json.h>
#include <rsocket/Payload.h>
#include <rsocket/RSocket.h>
#include <rsocket/transports/tcp/TcpConnectionFactory.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fstream>
#include <iostream>
#include <thread>
#include <folly/io/async/AsyncSocketException.h>
#include "CertificateUtils.h"

#ifdef __ANDROID__
#include <android/log.h>
#define SONAR_LOG(message) \
  __android_log_print(ANDROID_LOG_INFO, "sonar", "sonar: %s", message)
#else
#define SONAR_LOG(message) printf("sonar: %s\n", message)
#endif

#define CSR_FILE_NAME "app.csr"
#define SONAR_CA_FILE_NAME "sonarCA.crt"
#define CLIENT_CERT_FILE_NAME "device.crt"
#define PRIVATE_KEY_FILE "privateKey.pem"
#define CONNECTION_CONFIG_FILE "connection_config.json"
#define WRONG_THREAD_EXIT_MSG \
  "ERROR: Aborting sonar initialization because it's not running in the sonar thread."

static constexpr int reconnectIntervalSeconds = 2;
static constexpr int connectionKeepaliveSeconds = 10;
static constexpr int securePort = 8088;
static constexpr int insecurePort = 8089;

namespace facebook {
namespace sonar {

bool fileExists(std::string fileName);
void writeStringToFile(std::string content, std::string fileName);

class ConnectionEvents : public rsocket::RSocketConnectionEvents {
 private:
  SonarWebSocketImpl* websocket_;

 public:
  ConnectionEvents(SonarWebSocketImpl* websocket) : websocket_(websocket) {}

  void onConnected() {
    websocket_->isOpen_ = true;
    if (websocket_->connectionIsTrusted_) {
      websocket_->callbacks_->onConnected();
    }
  }

  void onDisconnected(const folly::exception_wrapper&) {
    if (!websocket_->isOpen_)
      return;
    websocket_->isOpen_ = false;
    if (websocket_->connectionIsTrusted_) {
      websocket_->connectionIsTrusted_ = false;
      websocket_->callbacks_->onDisconnected();
    }
    websocket_->reconnect();
  }

  void onClosed(const folly::exception_wrapper& e) {
    onDisconnected(e);
  }
};

class Responder : public rsocket::RSocketResponder {
 private:
  SonarWebSocketImpl* websocket_;

 public:
  Responder(SonarWebSocketImpl* websocket) : websocket_(websocket) {}

  void handleFireAndForget(
      rsocket::Payload request,
      rsocket::StreamId streamId) {
    const auto payload = request.moveDataToString();
    websocket_->callbacks_->onMessageReceived(folly::parseJson(payload));
  }
};

SonarWebSocketImpl::SonarWebSocketImpl(SonarInitConfig config, std::shared_ptr<SonarState> state)
    : deviceData_(config.deviceData), sonarState_(state), sonarEventBase_(config.callbackWorker), connectionEventBase_(config.connectionWorker) {}

SonarWebSocketImpl::~SonarWebSocketImpl() {
  stop();
}

void SonarWebSocketImpl::start() {
  auto step = sonarState_->start("Start connection thread");
  folly::makeFuture()
      .via(sonarEventBase_->getEventBase())
      .delayed(std::chrono::milliseconds(0))
      .thenValue([this, step](auto&&){ step->complete(); startSync(); });
}

void SonarWebSocketImpl::startSync() {
  if (!isRunningInOwnThread()) {
    SONAR_LOG(WRONG_THREAD_EXIT_MSG);
    return;
  }
  if (isOpen()) {
    SONAR_LOG("Already connected");
    return;
  }
  auto connect = sonarState_->start("Connect to desktop");
  try {
    if (isCertificateExchangeNeeded()) {
      doCertificateExchange();
      return;
    }

    connectSecurely();
    connect->complete();
  } catch (const folly::AsyncSocketException& e) {
    if (e.getType() == folly::AsyncSocketException::NOT_OPEN) {
      // The expected code path when flipper desktop is not running.
      // Don't count as a failed attempt.
      connect->fail("Port not open");
    } else {
      SONAR_LOG(e.what());
      failedConnectionAttempts_++;
      connect->fail(e.what());
    }
    reconnect();
  } catch (const std::exception& e) {
    SONAR_LOG(e.what());
    connect->fail(e.what());
    failedConnectionAttempts_++;
    reconnect();
  }
}

void SonarWebSocketImpl::doCertificateExchange() {

  rsocket::SetupParameters parameters;
  folly::SocketAddress address;

  parameters.payload = rsocket::Payload(
      folly::toJson(folly::dynamic::object("os", deviceData_.os)(
          "device", deviceData_.device)("app", deviceData_.app)));
  address.setFromHostPort(deviceData_.host, insecurePort);

  auto connectingInsecurely = sonarState_->start("Connect insecurely");
  connectionIsTrusted_ = false;
  client_ =
      rsocket::RSocket::createConnectedClient(
          std::make_unique<rsocket::TcpConnectionFactory>(
              *connectionEventBase_->getEventBase(), std::move(address)),
          std::move(parameters),
          nullptr,
          std::chrono::seconds(connectionKeepaliveSeconds), // keepaliveInterval
          nullptr, // stats
          std::make_shared<ConnectionEvents>(this))
          .get();
  connectingInsecurely->complete();

  ensureSonarDirExists();
  requestSignedCertFromSonar();
}

void SonarWebSocketImpl::connectSecurely() {
  rsocket::SetupParameters parameters;
  folly::SocketAddress address;

  auto deviceId = getDeviceId();

  parameters.payload = rsocket::Payload(folly::toJson(folly::dynamic::object(
      "os", deviceData_.os)("device", deviceData_.device)(
      "device_id", deviceId)("app", deviceData_.app)));
  address.setFromHostPort(deviceData_.host, securePort);

  std::shared_ptr<folly::SSLContext> sslContext =
      std::make_shared<folly::SSLContext>();
  sslContext->loadTrustedCertificates(
      absoluteFilePath(SONAR_CA_FILE_NAME).c_str());
  sslContext->setVerificationOption(
      folly::SSLContext::SSLVerifyPeerEnum::VERIFY);
  sslContext->loadCertKeyPairFromFiles(
      absoluteFilePath(CLIENT_CERT_FILE_NAME).c_str(),
      absoluteFilePath(PRIVATE_KEY_FILE).c_str());
  sslContext->authenticate(true, false);

  auto connectingSecurely = sonarState_->start("Connect securely");
  connectionIsTrusted_ = true;
  client_ =
      rsocket::RSocket::createConnectedClient(
          std::make_unique<rsocket::TcpConnectionFactory>(
              *connectionEventBase_->getEventBase(),
              std::move(address),
              std::move(sslContext)),
          std::move(parameters),
          std::make_shared<Responder>(this),
          std::chrono::seconds(connectionKeepaliveSeconds), // keepaliveInterval
          nullptr, // stats
          std::make_shared<ConnectionEvents>(this))
          .get();
  connectingSecurely->complete();
  failedConnectionAttempts_ = 0;
}

void SonarWebSocketImpl::reconnect() {
  folly::makeFuture()
      .via(sonarEventBase_->getEventBase())
      .delayed(std::chrono::seconds(reconnectIntervalSeconds))
      .thenValue([this](auto&&){ startSync(); });
}

void SonarWebSocketImpl::stop() {
  if (client_) {
    client_->disconnect();
  }
  client_ = nullptr;
}

bool SonarWebSocketImpl::isOpen() const {
  return isOpen_ && connectionIsTrusted_;
}

void SonarWebSocketImpl::setCallbacks(Callbacks* callbacks) {
  callbacks_ = callbacks;
}

void SonarWebSocketImpl::sendMessage(const folly::dynamic& message) {
  sonarEventBase_->add([this, message]() {
    if (client_) {
      client_->getRequester()
          ->fireAndForget(rsocket::Payload(folly::toJson(message)))
          ->subscribe([]() {});
    }
  });
}

std::string SonarWebSocketImpl::getDeviceId() {
  /* On android we can't reliably get the serial of the current device
     So rely on our locally written config, which is provided by the
     desktop app.
     For backwards compatibility, when this isn't present, fall back to the
     unreliable source. */
  auto gettingDeviceId = sonarState_->start("Get deviceId");
  std::string config = loadStringFromFile(absoluteFilePath(CONNECTION_CONFIG_FILE));
  auto maybeDeviceId = folly::parseJson(config)["deviceId"];
  std::string deviceId;
  if (maybeDeviceId.isString()) {
    deviceId = maybeDeviceId.getString();
  } else {
    deviceId = deviceData_.deviceId;
  }
  if (deviceId.compare("unknown")) {
    gettingDeviceId->complete();
  }
  return deviceId;
}

bool SonarWebSocketImpl::isCertificateExchangeNeeded() {

  if (failedConnectionAttempts_ >= 2) {
    return true;
  }

  auto step = sonarState_->start("Check required certificates are present");
  std::string caCert = loadStringFromFile(absoluteFilePath(SONAR_CA_FILE_NAME));
  std::string clientCert =
      loadStringFromFile(absoluteFilePath(CLIENT_CERT_FILE_NAME));
  std::string privateKey =
      loadStringFromFile(absoluteFilePath(PRIVATE_KEY_FILE));

  if (caCert == "" || clientCert == "" || privateKey == "") {
    return true;
  }
  step->complete();
  return false;
}

void SonarWebSocketImpl::requestSignedCertFromSonar() {
  auto generatingCSR = sonarState_->start("Generate CSR");
  generateCertSigningRequest(
      deviceData_.appId.c_str(),
      absoluteFilePath(CSR_FILE_NAME).c_str(),
      absoluteFilePath(PRIVATE_KEY_FILE).c_str());
  generatingCSR->complete();
  auto loadingCSR = sonarState_->start("Load CSR");
  std::string csr = loadStringFromFile(absoluteFilePath(CSR_FILE_NAME));
  loadingCSR->complete();

  folly::dynamic message = folly::dynamic::object("method", "signCertificate")(
      "csr", csr.c_str())("destination", absoluteFilePath("").c_str());
  auto gettingCert = sonarState_->start("Getting cert from desktop");

  sonarEventBase_->add([this, message, gettingCert]() {
    client_->getRequester()
        ->requestResponse(rsocket::Payload(folly::toJson(message)))
        ->subscribe([this, gettingCert](rsocket::Payload p) {
          auto response = p.moveDataToString();
          writeStringToFile(response, absoluteFilePath(CONNECTION_CONFIG_FILE));
          gettingCert->complete();
          SONAR_LOG("Certificate exchange complete.");
          // Disconnect after message sending is complete.
          // This will trigger a reconnect which should use the secure channel.
          // TODO: Connect immediately, without waiting for reconnect
          client_ = nullptr;
        },
        [this, message](folly::exception_wrapper e) {
          e.handle(
            [&](rsocket::ErrorWithPayload& errorWithPayload) {
              std::string errorMessage = errorWithPayload.payload.moveDataToString();

             if (errorMessage.compare("not implemented")) {
               SONAR_LOG(("Desktop failed to provide certificates. Error from sonar desktop:\n" + errorMessage).c_str());
             } else {
              sendLegacyCertificateRequest(message);
             }
            },
            [e](...) {
             SONAR_LOG(("Error during certificate exchange:" + e.what()).c_str());
            }
          );
        });
  });
  failedConnectionAttempts_ = 0;
}

void SonarWebSocketImpl::sendLegacyCertificateRequest(folly::dynamic message) {
  // Desktop is using an old version of Flipper.
  // Fall back to fireAndForget, instead of requestResponse.
  auto sendingRequest = sonarState_->start("Sending fallback certificate request");
  client_->getRequester()
   ->fireAndForget(rsocket::Payload(folly::toJson(message)))
   ->subscribe([this, sendingRequest]() {
     sendingRequest->complete();
     client_ = nullptr;
   });
}

std::string SonarWebSocketImpl::loadStringFromFile(std::string fileName) {
  if (!fileExists(fileName)) {
    return "";
  }
  std::stringstream buffer;
  std::ifstream stream;
  std::string line;
  stream.open(fileName.c_str());
  if (!stream) {
    SONAR_LOG(
        std::string("ERROR: Unable to open ifstream: " + fileName).c_str());
    return "";
  }
  buffer << stream.rdbuf();
  std::string s = buffer.str();
  return s;
}

void writeStringToFile(std::string content, std::string fileName) {
  std::ofstream out(fileName);
  out << content;
}

std::string SonarWebSocketImpl::absoluteFilePath(const char* filename) {
  return std::string(deviceData_.privateAppDirectory + "/sonar/" + filename);
}

bool SonarWebSocketImpl::ensureSonarDirExists() {
  std::string dirPath = absoluteFilePath("");
  struct stat info;
  if (stat(dirPath.c_str(), &info) != 0) {
    int ret = mkdir(dirPath.c_str(), S_IRUSR | S_IWUSR | S_IXUSR);
    return ret == 0;
  } else if (info.st_mode & S_IFDIR) {
    return true;
  } else {
    SONAR_LOG(std::string(
                  "ERROR: Sonar path exists but is not a directory: " + dirPath)
                  .c_str());
    return false;
  }
}

bool SonarWebSocketImpl::isRunningInOwnThread() {
  return sonarEventBase_->isInEventBaseThread();
}

bool fileExists(std::string fileName) {
  struct stat buffer;
  return stat(fileName.c_str(), &buffer) == 0;
}

} // namespace sonar
} // namespace facebook