core: Properly parent QObject-derived attributes
[quassel.git] / src / core / core.cpp
index 77280c3..b103b42 100644 (file)
@@ -1,5 +1,5 @@
 /***************************************************************************
- *   Copyright (C) 2005-09 by the Quassel Project                          *
+ *   Copyright (C) 2005-2018 by the Quassel Project                        *
  *   devel@quassel-irc.org                                                 *
  *                                                                         *
  *   This program is free software; you can redistribute it and/or modify  *
  *   You should have received a copy of the GNU General Public License     *
  *   along with this program; if not, write to the                         *
  *   Free Software Foundation, Inc.,                                       *
- *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
+ *   51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.         *
  ***************************************************************************/
 
+#include <algorithm>
+
 #include <QCoreApplication>
 
 #include "core.h"
+#include "coreauthhandler.h"
 #include "coresession.h"
 #include "coresettings.h"
+#include "logger.h"
+#include "internalpeer.h"
+#include "network.h"
 #include "postgresqlstorage.h"
 #include "quassel.h"
-#include "signalproxy.h"
+#include "sqlauthenticator.h"
 #include "sqlitestorage.h"
-#include "network.h"
-#include "logger.h"
-
 #include "util.h"
 
+// Currently building with LDAP bindings is optional.
+#ifdef HAVE_LDAP
+#include "ldapauthenticator.h"
+#endif
+
 // migration related
 #include <QFile>
+#ifdef Q_OS_WIN
+#  include <windows.h>
+#else
+#  include <unistd.h>
+#  include <termios.h>
+#endif /* Q_OS_WIN */
 
-Core *Core::instanceptr = 0;
+// ==============================
+//  Custom Events
+// ==============================
+const int Core::AddClientEventId = QEvent::registerEventType();
+
+class AddClientEvent : public QEvent
+{
+public:
+    AddClientEvent(RemotePeer *p, UserId uid) : QEvent(QEvent::Type(Core::AddClientEventId)), peer(p), userId(uid) {}
+    RemotePeer *peer;
+    UserId userId;
+};
 
-Core *Core::instance() {
-  if(instanceptr) return instanceptr;
-  instanceptr = new Core();
-  instanceptr->init();
-  return instanceptr;
-}
 
-void Core::destroy() {
-  delete instanceptr;
-  instanceptr = 0;
+// ==============================
+//  Core
+// ==============================
+Core *Core::_instance{nullptr};
+
+Core *Core::instance()
+{
+    return _instance;
 }
 
+
 Core::Core()
-  : _storage(0)
 {
-  _startTime = QDateTime::currentDateTime().toUTC();  // for uptime :)
+    if (_instance) {
+        qWarning() << "Recreating core instance!";
+        delete _instance;
+    }
+    _instance = this;
 
-  Quassel::loadTranslation(QLocale::system());
+    // Parent all QObject-derived attributes, so when the Core instance gets moved into another
+    // thread, they get moved with it
+    _server.setParent(this);
+    _v6server.setParent(this);
+    _storageSyncTimer.setParent(this);
+}
 
-  // FIXME: MIGRATION 0.3 -> 0.4: Move database and core config to new location
-  // Move settings, note this does not delete the old files
-#ifdef Q_WS_MAC
-    QSettings newSettings("quassel-irc.org", "quasselcore");
-#else
 
-# ifdef Q_WS_WIN
-    QSettings::Format format = QSettings::IniFormat;
-# else
-    QSettings::Format format = QSettings::NativeFormat;
-# endif
-    QString newFilePath = Quassel::configDirPath() + "quasselcore"
-    + ((format == QSettings::NativeFormat) ? QLatin1String(".conf") : QLatin1String(".ini"));
-    QSettings newSettings(newFilePath, format);
-#endif /* Q_WS_MAC */
-
-  if(newSettings.value("Config/Version").toUInt() == 0) {
-#   ifdef Q_WS_MAC
-    QString org = "quassel-irc.org";
-#   else
-    QString org = "Quassel Project";
-#   endif
-    QSettings oldSettings(org, "Quassel Core");
-    if(oldSettings.allKeys().count()) {
-      qWarning() << "\n\n*** IMPORTANT: Config and data file locations have changed. Attempting to auto-migrate your core settings...";
-      foreach(QString key, oldSettings.allKeys())
-        newSettings.setValue(key, oldSettings.value(key));
-      newSettings.setValue("Config/Version", 1);
-      qWarning() << "*   Your core settings have been migrated to" << newSettings.fileName();
-
-#ifndef Q_WS_MAC /* we don't need to move the db and cert for mac */
-#ifdef Q_OS_WIN32
-      QString quasselDir = qgetenv("APPDATA") + "/quassel/";
-#elif defined Q_WS_MAC
-      QString quasselDir = QDir::homePath() + "/Library/Application Support/Quassel/";
-#else
-      QString quasselDir = QDir::homePath() + "/.quassel/";
-#endif
+Core::~Core()
+{
+    saveState();
+    qDeleteAll(_connectingClients);
+    qDeleteAll(_sessions);
+    syncStorage();
+    _instance = nullptr;
+}
+
 
-      QFileInfo info(Quassel::configDirPath() + "quassel-storage.sqlite");
-      if(!info.exists()) {
-      // move database, if we found it
-        QFile oldDb(quasselDir + "quassel-storage.sqlite");
-        if(oldDb.exists()) {
-          bool success = oldDb.rename(Quassel::configDirPath() + "quassel-storage.sqlite");
-          if(success)
-            qWarning() << "*   Your database has been moved to" << Quassel::configDirPath() + "quassel-storage.sqlite";
-          else
-            qWarning() << "!!! Moving your database has failed. Please move it manually into" << Quassel::configDirPath();
+bool Core::init()
+{
+    _startTime = QDateTime::currentDateTime().toUTC(); // for uptime :)
+
+    Quassel::loadTranslation(QLocale::system());
+
+    // check settings version
+    // so far, we only have 1
+    CoreSettings s;
+    if (s.version() != 1) {
+        qCritical() << "Invalid core settings version, terminating!";
+        QCoreApplication::exit(EXIT_FAILURE);
+        return false;
+    }
+
+    // Set up storage and authentication backends
+    registerStorageBackends();
+    registerAuthenticators();
+
+    QProcessEnvironment environment = QProcessEnvironment::systemEnvironment();
+    bool config_from_environment = Quassel::isOptionSet("config-from-environment");
+
+    QString db_backend;
+    QVariantMap db_connectionProperties;
+
+    QString auth_authenticator;
+    QVariantMap auth_properties;
+
+    bool writeError = false;
+
+    if (config_from_environment) {
+        db_backend = environment.value("DB_BACKEND");
+        auth_authenticator = environment.value("AUTH_AUTHENTICATOR");
+    } else {
+        CoreSettings cs;
+
+        QVariantMap dbsettings = cs.storageSettings().toMap();
+        db_backend = dbsettings.value("Backend").toString();
+        db_connectionProperties = dbsettings.value("ConnectionProperties").toMap();
+
+        QVariantMap authSettings = cs.authSettings().toMap();
+        auth_authenticator = authSettings.value("Authenticator", "Database").toString();
+        auth_properties = authSettings.value("AuthProperties").toMap();
+
+        writeError = !cs.isWritable();
+    }
+
+    // legacy
+    _configured = initStorage(db_backend, db_connectionProperties, environment, config_from_environment);
+
+    // Not entirely sure what is 'legacy' about the above, but it seems to be the way things work!
+    if (_configured) {
+        initAuthenticator(auth_authenticator, auth_properties, environment, config_from_environment);
+    }
+
+    if (Quassel::isOptionSet("select-backend") || Quassel::isOptionSet("select-authenticator")) {
+        bool success{true};
+        if (Quassel::isOptionSet("select-backend")) {
+            success &= selectBackend(Quassel::optionValue("select-backend"));
+        }
+        if (Quassel::isOptionSet("select-authenticator")) {
+            success &= selectAuthenticator(Quassel::optionValue("select-authenticator"));
+        }
+        QCoreApplication::exit(success ? EXIT_SUCCESS : EXIT_FAILURE);
+        return success;
+    }
+
+    if (!_configured) {
+        if (config_from_environment) {
+            _configured = initStorage(db_backend, db_connectionProperties, environment, config_from_environment, true);
+            initAuthenticator(auth_authenticator, auth_properties, environment, config_from_environment, true);
+
+            if (!_configured) {
+                qWarning() << "Cannot configure from environment";
+                QCoreApplication::exit(EXIT_FAILURE);
+                return false;
+            }
+        }
+        else {
+            if (_registeredStorageBackends.empty()) {
+                quWarning() << qPrintable(tr("Could not initialize any storage backend! Exiting..."));
+                quWarning()
+                        << qPrintable(tr("Currently, Quassel supports SQLite3 and PostgreSQL. You need to build your\n"
+                                         "Qt library with the sqlite or postgres plugin enabled in order for quasselcore\n"
+                                         "to work."));
+                QCoreApplication::exit(EXIT_FAILURE); // TODO make this less brutal (especially for mono client -> popup)
+                return false;
+            }
+
+            if (writeError) {
+                qWarning() << "Cannot write quasselcore configuration; probably a permission problem.";
+                QCoreApplication::exit(EXIT_FAILURE);
+                return false;
+            }
+
+            quInfo() << "Core is currently not configured! Please connect with a Quassel Client for basic setup.";
         }
-      }
-      // move certificate
-      QFileInfo certInfo(quasselDir + "quasselCert.pem");
-      if(certInfo.exists()) {
-        QFile cert(quasselDir + "quasselCert.pem");
-        bool success = cert.rename(Quassel::configDirPath() + "quasselCert.pem");
-        if(success)
-          qWarning() << "*   Your certificate has been moved to" << Quassel::configDirPath() + "quasselCert.pem";
-        else
-          qWarning() << "!!! Moving your certificate has failed. Please move it manually into" << Quassel::configDirPath();
-      }
-#endif /* !Q_WS_MAC */
-      qWarning() << "*** Migration completed.\n\n";
     }
-  }
-  // MIGRATION end
+    else {
+        if (Quassel::isOptionSet("add-user")) {
+            bool success = createUser();
+            QCoreApplication::exit(success ? EXIT_SUCCESS : EXIT_FAILURE);
+            return success;
+        }
 
-  // check settings version
-  // so far, we only have 1
-  CoreSettings s;
-  if(s.version() != 1) {
-    qCritical() << "Invalid core settings version, terminating!";
-    exit(EXIT_FAILURE);
-  }
+        if (Quassel::isOptionSet("change-userpass")) {
+            bool success = changeUserPass(Quassel::optionValue("change-userpass"));
+            QCoreApplication::exit(success ? EXIT_SUCCESS : EXIT_FAILURE);
+            return success;
+        }
 
-  registerStorageBackends();
+        _strictIdentEnabled = Quassel::isOptionSet("strict-ident");
+        if (_strictIdentEnabled) {
+            cacheSysIdent();
+        }
 
-  connect(&_storageSyncTimer, SIGNAL(timeout()), this, SLOT(syncStorage()));
-  _storageSyncTimer.start(10 * 60 * 1000); // 10 minutes
-}
+        if (Quassel::isOptionSet("oidentd")) {
+            _oidentdConfigGenerator = new OidentdConfigGenerator(this);
+        }
 
-void Core::init() {
-  if(Quassel::isOptionSet("select-backend")) {
-    switchBackend(Quassel::optionValue("select-backend"));
-    exit(0);
-  }
+        Quassel::registerReloadHandler([]() {
+            // Currently, only reloading SSL certificates and the sysident cache is supported
+            if (Core::instance()) {
+                Core::instance()->cacheSysIdent();
+                Core::instance()->reloadCerts();
+                return true;
+            }
+            return false;
+        });
+
+        connect(&_storageSyncTimer, SIGNAL(timeout()), this, SLOT(syncStorage()));
+        _storageSyncTimer.start(10 * 60 * 1000); // 10 minutes
+    }
 
-  CoreSettings cs;
-  _configured = initStorage(cs.storageSettings().toMap());
+    connect(&_server, SIGNAL(newConnection()), this, SLOT(incomingConnection()));
+    connect(&_v6server, SIGNAL(newConnection()), this, SLOT(incomingConnection()));
 
-  if(!_configured) {
-    if(!_storageBackends.count()) {
-      qWarning() << qPrintable(tr("Could not initialize any storage backend! Exiting..."));
-      qWarning() << qPrintable(tr("Currently, Quassel supports SQLite3 and PostgreSQL. You need to build your\n"
-                                 "Qt library with the sqlite or postgres plugin enabled in order for quasselcore\n"
-                                 "to work."));
-      exit(1); // TODO make this less brutal (especially for mono client -> popup)
+    if (!startListening()) {
+        QCoreApplication::exit(EXIT_FAILURE);  // TODO make this less brutal
+        return false;
     }
-    qWarning() << "Core is currently not configured! Please connect with a Quassel Client for basic setup.";
-  }
 
-  if(Quassel::isOptionSet("migrate-backend")) {
-    migrateBackend(Quassel::optionValue("migrate-backend"));
-    exit(0);
-  }
+    if (_configured && !Quassel::isOptionSet("norestore")) {
+        Core::restoreState();
+    }
 
-  connect(&_server, SIGNAL(newConnection()), this, SLOT(incomingConnection()));
-  connect(&_v6server, SIGNAL(newConnection()), this, SLOT(incomingConnection()));
-  if(!startListening()) exit(1); // TODO make this less brutal
+    return true;
 }
 
-Core::~Core() {
-  foreach(QTcpSocket *socket, blocksizes.keys()) {
-    socket->disconnectFromHost();  // disconnect non authed clients
-  }
-  qDeleteAll(sessions);
-  qDeleteAll(_storageBackends);
+/*** Session Restore ***/
+
+void Core::saveState()
+{
+    if (_storage) {
+        QVariantList activeSessions;
+        for (auto &&user : instance()->_sessions.keys())
+            activeSessions << QVariant::fromValue<UserId>(user);
+        _storage->setCoreState(activeSessions);
+    }
 }
 
-/*** Session Restore ***/
 
-void Core::saveState() {
-  CoreSettings s;
-  QVariantMap state;
-  QVariantList activeSessions;
-  foreach(UserId user, instance()->sessions.keys()) activeSessions << QVariant::fromValue<UserId>(user);
-  state["CoreStateVersion"] = 1;
-  state["ActiveSessions"] = activeSessions;
-  s.setCoreState(state);
-}
-
-void Core::restoreState() {
-  if(!instance()->_configured) {
-    // qWarning() << qPrintable(tr("Cannot restore a state for an unconfigured core!"));
-    return;
-  }
-  if(instance()->sessions.count()) {
-    qWarning() << qPrintable(tr("Calling restoreState() even though active sessions exist!"));
-    return;
-  }
-  CoreSettings s;
-  /* We don't check, since we are at the first version since switching to Git
-  uint statever = s.coreState().toMap()["CoreStateVersion"].toUInt();
-  if(statever < 1) {
-    qWarning() << qPrintable(tr("Core state too old, ignoring..."));
-    return;
-  }
-  */
-  QVariantList activeSessions = s.coreState().toMap()["ActiveSessions"].toList();
-  if(activeSessions.count() > 0) {
-    quInfo() << "Restoring previous core state...";
-    foreach(QVariant v, activeSessions) {
-      UserId user = v.value<UserId>();
-      instance()->createSession(user, true);
-    }
-  }
+void Core::restoreState()
+{
+    if (!_configured) {
+        quWarning() << qPrintable(tr("Cannot restore a state for an unconfigured core!"));
+        return;
+    }
+    if (_sessions.count()) {
+        quWarning() << qPrintable(tr("Calling restoreState() even though active sessions exist!"));
+        return;
+    }
+
+    CoreSettings s;
+    /* We don't check, since we are at the first version since switching to Git
+    uint statever = s.coreState().toMap()["CoreStateVersion"].toUInt();
+    if(statever < 1) {
+      quWarning() << qPrintable(tr("Core state too old, ignoring..."));
+      return;
+    }
+    */
+
+    const QList<QVariant> &activeSessionsFallback = s.coreState().toMap()["ActiveSessions"].toList();
+    QVariantList activeSessions = instance()->_storage->getCoreState(activeSessionsFallback);
+
+    if (activeSessions.count() > 0) {
+        quInfo() << "Restoring previous core state...";
+        for(auto &&v : activeSessions) {
+            UserId user = v.value<UserId>();
+            sessionForUser(user, true);
+        }
+    }
 }
 
+
 /*** Core Setup ***/
-QString Core::setupCoreForInternalUsage() {
-  Q_ASSERT(!_storageBackends.isEmpty());
-  QVariantMap setupData;
-  qsrand(QDateTime::currentDateTime().toTime_t());
-  int pass = 0;
-  for(int i = 0; i < 10; i++) {
-    pass *= 10;
-    pass += qrand() % 10;
-  }
-  setupData["AdminUser"] = "AdminUser";
-  setupData["AdminPasswd"] = QString::number(pass);
-  setupData["Backend"] = _storageBackends[_storageBackends.keys().first()]->displayName();
-  return setupCore(setupData);
-}
-
-QString Core::setupCore(QVariantMap setupData) {
-  QString user = setupData.take("AdminUser").toString();
-  QString password = setupData.take("AdminPasswd").toString();
-  if(user.isEmpty() || password.isEmpty()) {
-    return tr("Admin user or password not set.");
-  }
-  _configured = initStorage(setupData, true);
-  if(!_configured) {
-    return tr("Could not setup storage!");
-  }
-  CoreSettings s;
-  s.setStorageSettings(setupData);
-  quInfo() << qPrintable(tr("Creating admin user..."));
-  _storage->addUser(user, password);
-  startListening();  // TODO check when we need this
-  return QString();
+
+QString Core::setup(const QString &adminUser, const QString &adminPassword, const QString &backend, const QVariantMap &setupData, const QString &authenticator, const QVariantMap &authSetupData)
+{
+    return instance()->setupCore(adminUser, adminPassword, backend, setupData, authenticator, authSetupData);
 }
 
-/*** Storage Handling ***/
-void Core::registerStorageBackends() {
-  // Register storage backends here!
-  registerStorageBackend(new SqliteStorage(this));
-  registerStorageBackend(new PostgreSqlStorage(this));
+
+QString Core::setupCore(const QString &adminUser, const QString &adminPassword, const QString &backend, const QVariantMap &setupData, const QString &authenticator, const QVariantMap &authSetupData)
+{
+    if (_configured)
+        return tr("Core is already configured! Not configuring again...");
+
+    if (adminUser.isEmpty() || adminPassword.isEmpty()) {
+        return tr("Admin user or password not set.");
+    }
+    if (!(_configured = initStorage(backend, setupData, {}, false, true))) {
+        return tr("Could not setup storage!");
+    }
+
+    quInfo() << "Selected authenticator:" << authenticator;
+    if (!(_configured = initAuthenticator(authenticator, authSetupData, {}, false, true)))
+    {
+        return tr("Could not setup authenticator!");
+    }
+
+    if (!saveBackendSettings(backend, setupData)) {
+        return tr("Could not save backend settings, probably a permission problem.");
+    }
+    saveAuthenticatorSettings(authenticator, authSetupData);
+
+    quInfo() << qPrintable(tr("Creating admin user..."));
+    _storage->addUser(adminUser, adminPassword);
+    cacheSysIdent();
+    startListening(); // TODO check when we need this
+    return QString();
 }
 
-bool Core::registerStorageBackend(Storage *backend) {
-  if(backend->isAvailable()) {
-    _storageBackends[backend->displayName()] = backend;
-    return true;
-  } else {
-    backend->deleteLater();
-    return false;
-  }
+
+QString Core::setupCoreForInternalUsage()
+{
+    Q_ASSERT(!_registeredStorageBackends.empty());
+
+    qsrand(QDateTime::currentDateTime().toMSecsSinceEpoch());
+    int pass = 0;
+    for (int i = 0; i < 10; i++) {
+        pass *= 10;
+        pass += qrand() % 10;
+    }
+
+    // mono client currently needs sqlite
+    return setupCore("AdminUser", QString::number(pass), "SQLite", QVariantMap(), "Database", QVariantMap());
+}
+
+
+/*** Storage Handling ***/
+
+template<typename Storage>
+void Core::registerStorageBackend()
+{
+    auto backend = makeDeferredShared<Storage>(this);
+    if (backend->isAvailable())
+        _registeredStorageBackends.emplace_back(std::move(backend));
+    else
+        backend->deleteLater();
 }
 
-void Core::unregisterStorageBackends() {
-  foreach(Storage *s, _storageBackends.values()) {
-    s->deleteLater();
-  }
-  _storageBackends.clear();
+
+void Core::registerStorageBackends()
+{
+    if (_registeredStorageBackends.empty()) {
+        registerStorageBackend<SqliteStorage>();
+        registerStorageBackend<PostgreSqlStorage>();
+    }
 }
 
-void Core::unregisterStorageBackend(Storage *backend) {
-  _storageBackends.remove(backend->displayName());
-  backend->deleteLater();
+
+DeferredSharedPtr<Storage> Core::storageBackend(const QString &backendId) const
+{
+    auto it = std::find_if(_registeredStorageBackends.begin(), _registeredStorageBackends.end(),
+                           [backendId](const DeferredSharedPtr<Storage> &backend) {
+                               return backend->displayName() == backendId;
+                           });
+    return it != _registeredStorageBackends.end() ? *it : nullptr;
 }
 
 // old db settings:
 // "Type" => "sqlite"
-bool Core::initStorage(const QString &backend, QVariantMap settings, bool setup) {
-  _storage = 0;
+bool Core::initStorage(const QString &backend, const QVariantMap &settings,
+                       const QProcessEnvironment &environment, bool loadFromEnvironment, bool setup)
+{
+    if (backend.isEmpty()) {
+        quWarning() << "No storage backend selected!";
+        return false;
+    }
 
-  if(backend.isEmpty()) {
-    return false;
-  }
+    auto storage = storageBackend(backend);
+    if (!storage) {
+        qCritical() << "Selected storage backend is not available:" << backend;
+        return false;
+    }
 
-  Storage *storage = 0;
-  if(_storageBackends.contains(backend)) {
-    storage = _storageBackends[backend];
-  } else {
-    qCritical() << "Selected storage backend is not available:" << backend;
-    return false;
-  }
-
-  Storage::State storageState = storage->init(settings);
-  switch(storageState) {
-  case Storage::NeedsSetup:
-    if(!setup)
-      return false; // trigger setup process
-    if(storage->setup(settings))
-      return initStorage(backend, settings, false);
-    // if setup wasn't successfull we mark the backend as unavailable
-  case Storage::NotAvailable:
-    qCritical() << "Selected storage backend is not available:" << backend;
-    storage->deleteLater();
-    _storageBackends.remove(backend);
-    storage = 0;
-    return false;
-  case Storage::IsReady:
-    // delete all other backends
-    _storageBackends.remove(backend);
-    unregisterStorageBackends();
-    connect(storage, SIGNAL(bufferInfoUpdated(UserId, const BufferInfo &)), this, SIGNAL(bufferInfoUpdated(UserId, const BufferInfo &)));
-  }
-  _storage = storage;
-  return true;
+    Storage::State storageState = storage->init(settings, environment, loadFromEnvironment);
+    switch (storageState) {
+    case Storage::NeedsSetup:
+        if (!setup)
+            return false;  // trigger setup process
+        if (storage->setup(settings, environment, loadFromEnvironment))
+            return initStorage(backend, settings, environment, loadFromEnvironment, false);
+        return false;
+
+    // if initialization wasn't successful, we quit to keep from coming up unconfigured
+    case Storage::NotAvailable:
+        qCritical() << "FATAL: Selected storage backend is not available:" << backend;
+        if (!setup) {
+            QCoreApplication::exit(EXIT_FAILURE);
+        }
+        return false;
+
+    case Storage::IsReady:
+        // delete all other backends
+        _registeredStorageBackends.clear();
+        connect(storage.get(), SIGNAL(bufferInfoUpdated(UserId, const BufferInfo &)),
+                this, SIGNAL(bufferInfoUpdated(UserId, const BufferInfo &)));
+        break;
+    }
+    _storage = std::move(storage);
+    return true;
 }
 
-bool Core::initStorage(QVariantMap dbSettings, bool setup) {
-  return initStorage(dbSettings["Backend"].toString(), dbSettings["ConnectionProperties"].toMap(), setup);
+
+void Core::syncStorage()
+{
+    if (_storage)
+        _storage->sync();
 }
 
 
-void Core::syncStorage() {
-  if(_storage)
-    _storage->sync();
+/*** Storage Access ***/
+bool Core::createNetwork(UserId user, NetworkInfo &info)
+{
+    NetworkId networkId = instance()->_storage->createNetwork(user, info);
+    if (!networkId.isValid())
+        return false;
+
+    info.networkId = networkId;
+    return true;
 }
 
-/*** Storage Access ***/
-bool Core::createNetwork(UserId user, NetworkInfo &info) {
-  NetworkId networkId = instance()->_storage->createNetwork(user, info);
-  if(!networkId.isValid())
-    return false;
 
-  info.networkId = networkId;
-  return true;
+/*** Authenticators ***/
+
+// Authentication handling, now independent from storage.
+template<typename Authenticator>
+void Core::registerAuthenticator()
+{
+    auto authenticator = makeDeferredShared<Authenticator>(this);
+    if (authenticator->isAvailable())
+        _registeredAuthenticators.emplace_back(std::move(authenticator));
+    else
+        authenticator->deleteLater();
 }
 
-/*** Network Management ***/
 
-bool Core::startListening() {
-  // in mono mode we only start a local port if a port is specified in the cli call
-  if(Quassel::runMode() == Quassel::Monolithic && !Quassel::isOptionSet("port"))
-    return true;
+void Core::registerAuthenticators()
+{
+    if (_registeredAuthenticators.empty()) {
+        registerAuthenticator<SqlAuthenticator>();
+#ifdef HAVE_LDAP
+        registerAuthenticator<LdapAuthenticator>();
+#endif
+    }
+}
 
-  bool success = false;
-  uint port = Quassel::optionValue("port").toUInt();
-
-  const QString listen = Quassel::optionValue("listen");
-  const QStringList listen_list = listen.split(",", QString::SkipEmptyParts);
-  if(listen_list.size() > 0) {
-    foreach (const QString listen_term, listen_list) {  // TODO: handle multiple interfaces for same TCP version gracefully
-      QHostAddress addr;
-      if(!addr.setAddress(listen_term)) {
-        qCritical() << qPrintable(
-          tr("Invalid listen address %1")
-            .arg(listen_term)
-        );
-      } else {
-        switch(addr.protocol()) {
-          case QAbstractSocket::IPv4Protocol:
-            if(_server.listen(addr, port)) {
-              quInfo() << qPrintable(
-                tr("Listening for GUI clients on IPv4 %1 port %2 using protocol version %3")
-                  .arg(addr.toString())
-                  .arg(_server.serverPort())
-                  .arg(Quassel::buildInfo().protocolVersion)
-              );
-              success = true;
-            } else
-              quWarning() << qPrintable(
-                tr("Could not open IPv4 interface %1:%2: %3")
-                  .arg(addr.toString())
-                  .arg(port)
-                  .arg(_server.errorString()));
-            break;
-          case QAbstractSocket::IPv6Protocol:
-            if(_v6server.listen(addr, port)) {
-              quInfo() << qPrintable(
-                tr("Listening for GUI clients on IPv6 %1 port %2 using protocol version %3")
-                  .arg(addr.toString())
-                  .arg(_v6server.serverPort())
-                  .arg(Quassel::buildInfo().protocolVersion)
-              );
-              success = true;
-            } else {
-              // if v4 succeeded on Any, the port will be already in use - don't display the error then
-              // FIXME: handle this more sanely, make sure we can listen to both v4 and v6 by default!
-              if(!success || _v6server.serverError() != QAbstractSocket::AddressInUseError)
-                quWarning() << qPrintable(
-                  tr("Could not open IPv6 interface %1:%2: %3")
-                  .arg(addr.toString())
-                  .arg(port)
-                  .arg(_v6server.errorString()));
-            }
-            break;
-          default:
-            qCritical() << qPrintable(
-              tr("Invalid listen address %1, unknown network protocol")
-                  .arg(listen_term)
-            );
-            break;
+
+DeferredSharedPtr<Authenticator> Core::authenticator(const QString &backendId) const
+{
+    auto it = std::find_if(_registeredAuthenticators.begin(), _registeredAuthenticators.end(),
+                           [backendId](const DeferredSharedPtr<Authenticator> &authenticator) {
+                               return authenticator->backendId() == backendId;
+                           });
+    return it != _registeredAuthenticators.end() ? *it : nullptr;
+}
+
+
+// FIXME: Apparently, this is the legacy way of initting storage backends?
+// If there's a not-legacy way, it should be used here
+bool Core::initAuthenticator(const QString &backend, const QVariantMap &settings,
+                             const QProcessEnvironment &environment, bool loadFromEnvironment,
+                             bool setup)
+{
+    if (backend.isEmpty()) {
+        quWarning() << "No authenticator selected!";
+        return false;
+    }
+
+    auto auth = authenticator(backend);
+    if (!auth) {
+        qCritical() << "Selected auth backend is not available:" << backend;
+        return false;
+    }
+
+    Authenticator::State authState = auth->init(settings, environment, loadFromEnvironment);
+    switch (authState) {
+    case Authenticator::NeedsSetup:
+        if (!setup)
+            return false;  // trigger setup process
+        if (auth->setup(settings, environment, loadFromEnvironment))
+            return initAuthenticator(backend, settings, environment, loadFromEnvironment, false);
+        return false;
+
+    // if initialization wasn't successful, we quit to keep from coming up unconfigured
+    case Authenticator::NotAvailable:
+        qCritical() << "FATAL: Selected auth backend is not available:" << backend;
+        if (!setup) {
+            QCoreApplication::exit(EXIT_FAILURE);
         }
-      }
-    }
-  }
-  if(!success)
-    quError() << qPrintable(tr("Could not open any network interfaces to listen on!"));
-
-  return success;
-}
-
-void Core::stopListening(const QString &reason) {
-  bool wasListening = false;
-  if(_server.isListening()) {
-    wasListening = true;
-    _server.close();
-  }
-  if(_v6server.isListening()) {
-    wasListening = true;
-    _v6server.close();
-  }
-  if(wasListening) {
-    if(reason.isEmpty())
-      quInfo() << "No longer listening for GUI clients.";
-    else
-      quInfo() << qPrintable(reason);
-  }
-}
-
-void Core::incomingConnection() {
-  QTcpServer *server = qobject_cast<QTcpServer *>(sender());
-  Q_ASSERT(server);
-  while(server->hasPendingConnections()) {
-    QTcpSocket *socket = server->nextPendingConnection();
-    connect(socket, SIGNAL(disconnected()), this, SLOT(clientDisconnected()));
-    connect(socket, SIGNAL(readyRead()), this, SLOT(clientHasData()));
-    connect(socket, SIGNAL(error(QAbstractSocket::SocketError)), this, SLOT(socketError(QAbstractSocket::SocketError)));
-
-    QVariantMap clientInfo;
-    blocksizes.insert(socket, (quint32)0);
-    quInfo() << qPrintable(tr("Client connected from"))  << qPrintable(socket->peerAddress().toString());
-
-    if(!_configured) {
-      stopListening(tr("Closing server for basic setup."));
-    }
-  }
-}
-
-void Core::clientHasData() {
-  QTcpSocket *socket = dynamic_cast<QTcpSocket*>(sender());
-  Q_ASSERT(socket && blocksizes.contains(socket));
-  QVariant item;
-  while(SignalProxy::readDataFromDevice(socket, blocksizes[socket], item)) {
-    QVariantMap msg = item.toMap();
-    processClientMessage(socket, msg);
-    if(!blocksizes.contains(socket)) break;  // this socket is no longer ours to handle!
-  }
-}
-
-void Core::processClientMessage(QTcpSocket *socket, const QVariantMap &msg) {
-  if(!msg.contains("MsgType")) {
-    // Client is way too old, does not even use the current init format
-    qWarning() << qPrintable(tr("Antique client trying to connect... refusing."));
-    socket->close();
-    return;
-  }
-  // OK, so we have at least an init message format we can understand
-  if(msg["MsgType"] == "ClientInit") {
-    QVariantMap reply;
-
-    // Just version information -- check it!
-    uint ver = msg["ProtocolVersion"].toUInt();
-    if(ver < Quassel::buildInfo().coreNeedsProtocol) {
-      reply["MsgType"] = "ClientInitReject";
-      reply["Error"] = tr("<b>Your Quassel Client is too old!</b><br>"
-      "This core needs at least client/core protocol version %1.<br>"
-      "Please consider upgrading your client.").arg(Quassel::buildInfo().coreNeedsProtocol);
-      SignalProxy::writeDataToDevice(socket, reply);
-      qWarning() << qPrintable(tr("Client")) << qPrintable(socket->peerAddress().toString()) << qPrintable(tr("too old, rejecting."));
-      socket->close(); return;
-    }
-
-    reply["CoreVersion"] = Quassel::buildInfo().fancyVersionString;
-    reply["CoreDate"] = Quassel::buildInfo().buildDate;
-    reply["ProtocolVersion"] = Quassel::buildInfo().protocolVersion;
-    // TODO: Make the core info configurable
-    int uptime = startTime().secsTo(QDateTime::currentDateTime().toUTC());
-    int updays = uptime / 86400; uptime %= 86400;
-    int uphours = uptime / 3600; uptime %= 3600;
-    int upmins = uptime / 60;
-    reply["CoreInfo"] = tr("<b>Quassel Core Version %1</b><br>"
-                          "Built: %2<br>"
-                          "Up %3d%4h%5m (since %6)").arg(Quassel::buildInfo().fancyVersionString)
-                                                     .arg(Quassel::buildInfo().buildDate)
-      .arg(updays).arg(uphours,2,10,QChar('0')).arg(upmins,2,10,QChar('0')).arg(startTime().toString(Qt::TextDate));
+        return false;
+
+    case Authenticator::IsReady:
+        // delete all other backends
+        _registeredAuthenticators.clear();
+        break;
+    }
+    _authenticator = std::move(auth);
+    return true;
+}
+
 
+/*** Network Management ***/
+
+bool Core::sslSupported()
+{
 #ifdef HAVE_SSL
-    SslServer *sslServer = qobject_cast<SslServer *>(&_server);
-    QSslSocket *sslSocket = qobject_cast<QSslSocket *>(socket);
-    bool supportSsl = (bool)sslServer && (bool)sslSocket && sslServer->isCertValid();
+    SslServer *sslServer = qobject_cast<SslServer *>(&instance()->_server);
+    return sslServer && sslServer->isCertValid();
 #else
-    bool supportSsl = false;
+    return false;
 #endif
+}
+
+
+bool Core::reloadCerts()
+{
+#ifdef HAVE_SSL
+    SslServer *sslServerv4 = qobject_cast<SslServer *>(&_server);
+    bool retv4 = sslServerv4->reloadCerts();
 
-#ifndef QT_NO_COMPRESS
-    bool supportsCompression = true;
+    SslServer *sslServerv6 = qobject_cast<SslServer *>(&_v6server);
+    bool retv6 = sslServerv6->reloadCerts();
+
+    return retv4 && retv6;
 #else
-    bool supportsCompression = false;
+    // SSL not supported, don't mark configuration reload as failed
+    return true;
 #endif
+}
 
-    reply["SupportSsl"] = supportSsl;
-    reply["SupportsCompression"] = supportsCompression;
-    // switch to ssl/compression after client has been informed about our capabilities (see below)
 
-    reply["LoginEnabled"] = true;
+void Core::cacheSysIdent()
+{
+    if (isConfigured()) {
+        _authUserNames = _storage->getAllAuthUserNames();
+    }
+}
+
 
-    // check if we are configured, start wizard otherwise
-    if(!_configured) {
-      reply["Configured"] = false;
-      QList<QVariant> backends;
-      foreach(Storage *backend, _storageBackends.values()) {
-        QVariantMap v;
-        v["DisplayName"] = backend->displayName();
-        v["Description"] = backend->description();
-       v["SetupKeys"] = backend->setupKeys();
-       v["SetupDefaults"] = backend->setupDefaults();
-        backends.append(v);
-      }
-      reply["StorageBackends"] = backends;
-      reply["LoginEnabled"] = false;
-    } else {
-      reply["Configured"] = true;
+QString Core::strictSysIdent(UserId user) const
+{
+    if (_authUserNames.contains(user)) {
+        return _authUserNames[user];
     }
-    clientInfo[socket] = msg; // store for future reference
-    reply["MsgType"] = "ClientInitAck";
-    SignalProxy::writeDataToDevice(socket, reply);
 
-#ifdef HAVE_SSL
-    // after we told the client that we are ssl capable we switch to ssl mode
-    if(supportSsl && msg["UseSsl"].toBool()) {
-      qDebug() << qPrintable(tr("Starting TLS for Client:"))  << qPrintable(socket->peerAddress().toString());
-      connect(sslSocket, SIGNAL(sslErrors(const QList<QSslError> &)), this, SLOT(sslErrors(const QList<QSslError> &)));
-      sslSocket->startServerEncryption();
+    // A new user got added since we last pulled our cache from the database.
+    // There's no way to avoid a database hit - we don't even know the authname!
+    instance()->cacheSysIdent();
+
+    if (_authUserNames.contains(user)) {
+        return _authUserNames[user];
     }
-#endif
 
-#ifndef QT_NO_COMPRESS
-    if(supportsCompression && msg["UseCompression"].toBool()) {
-      socket->setProperty("UseCompression", true);
-      qDebug() << "Using compression for Client:" << qPrintable(socket->peerAddress().toString());
+    // ...something very weird is going on if we ended up here (an active CoreSession without a corresponding database entry?)
+    qWarning().nospace() << "Unable to find authusername for UserId " << user << ", this should never happen!";
+    return "unknown"; // Should we just terminate the program instead?
+}
+
+
+bool Core::startListening()
+{
+    // in mono mode we only start a local port if a port is specified in the cli call
+    if (Quassel::runMode() == Quassel::Monolithic && !Quassel::isOptionSet("port"))
+        return true;
+
+    bool success = false;
+    uint port = Quassel::optionValue("port").toUInt();
+
+    const QString listen = Quassel::optionValue("listen");
+    const QStringList listen_list = listen.split(",", QString::SkipEmptyParts);
+    if (listen_list.size() > 0) {
+        foreach(const QString listen_term, listen_list) { // TODO: handle multiple interfaces for same TCP version gracefully
+            QHostAddress addr;
+            if (!addr.setAddress(listen_term)) {
+                qCritical() << qPrintable(
+                    tr("Invalid listen address %1")
+                    .arg(listen_term)
+                    );
+            }
+            else {
+                switch (addr.protocol()) {
+                case QAbstractSocket::IPv6Protocol:
+                    if (_v6server.listen(addr, port)) {
+                        quInfo() << qPrintable(
+                            tr("Listening for GUI clients on IPv6 %1 port %2 using protocol version %3")
+                            .arg(addr.toString())
+                            .arg(_v6server.serverPort())
+                            .arg(Quassel::buildInfo().protocolVersion)
+                            );
+                        success = true;
+                    }
+                    else
+                        quWarning() << qPrintable(
+                            tr("Could not open IPv6 interface %1:%2: %3")
+                            .arg(addr.toString())
+                            .arg(port)
+                            .arg(_v6server.errorString()));
+                    break;
+                case QAbstractSocket::IPv4Protocol:
+                    if (_server.listen(addr, port)) {
+                        quInfo() << qPrintable(
+                            tr("Listening for GUI clients on IPv4 %1 port %2 using protocol version %3")
+                            .arg(addr.toString())
+                            .arg(_server.serverPort())
+                            .arg(Quassel::buildInfo().protocolVersion)
+                            );
+                        success = true;
+                    }
+                    else {
+                        // if v6 succeeded on Any, the port will be already in use - don't display the error then
+                        if (!success || _server.serverError() != QAbstractSocket::AddressInUseError)
+                            quWarning() << qPrintable(
+                                tr("Could not open IPv4 interface %1:%2: %3")
+                                .arg(addr.toString())
+                                .arg(port)
+                                .arg(_server.errorString()));
+                    }
+                    break;
+                default:
+                    qCritical() << qPrintable(
+                        tr("Invalid listen address %1, unknown network protocol")
+                        .arg(listen_term)
+                        );
+                    break;
+                }
+            }
+        }
     }
-#endif
+    if (!success)
+        quError() << qPrintable(tr("Could not open any network interfaces to listen on!"));
 
-  } else {
-    // for the rest, we need an initialized connection
-    if(!clientInfo.contains(socket)) {
-      QVariantMap reply;
-      reply["MsgType"] = "ClientLoginReject";
-      reply["Error"] = tr("<b>Client not initialized!</b><br>You need to send an init message before trying to login.");
-      SignalProxy::writeDataToDevice(socket, reply);
-      qWarning() << qPrintable(tr("Client")) << qPrintable(socket->peerAddress().toString()) << qPrintable(tr("did not send an init message before trying to login, rejecting."));
-      socket->close(); return;
-    }
-    if(msg["MsgType"] == "CoreSetupData") {
-      QVariantMap reply;
-      QString result = setupCore(msg["SetupData"].toMap());
-      if(!result.isEmpty()) {
-        reply["MsgType"] = "CoreSetupReject";
-        reply["Error"] = result;
-      } else {
-        reply["MsgType"] = "CoreSetupAck";
-      }
-      SignalProxy::writeDataToDevice(socket, reply);
-    } else if(msg["MsgType"] == "ClientLogin") {
-      QVariantMap reply;
-      UserId uid = _storage->validateUser(msg["User"].toString(), msg["Password"].toString());
-      if(uid == 0) {
-        reply["MsgType"] = "ClientLoginReject";
-        reply["Error"] = tr("<b>Invalid username or password!</b><br>The username/password combination you supplied could not be found in the database.");
-        SignalProxy::writeDataToDevice(socket, reply);
-        return;
-      }
-      reply["MsgType"] = "ClientLoginAck";
-      SignalProxy::writeDataToDevice(socket, reply);
-      quInfo() << qPrintable(tr("Client")) << qPrintable(socket->peerAddress().toString()) << qPrintable(tr("initialized and authenticated successfully as \"%1\" (UserId: %2).").arg(msg["User"].toString()).arg(uid.toInt()));
-      setupClientSession(socket, uid);
+    return success;
+}
+
+
+void Core::stopListening(const QString &reason)
+{
+    bool wasListening = false;
+    if (_server.isListening()) {
+        wasListening = true;
+        _server.close();
+    }
+    if (_v6server.isListening()) {
+        wasListening = true;
+        _v6server.close();
+    }
+    if (wasListening) {
+        if (reason.isEmpty())
+            quInfo() << "No longer listening for GUI clients.";
+        else
+            quInfo() << qPrintable(reason);
+    }
+}
+
+
+void Core::incomingConnection()
+{
+    QTcpServer *server = qobject_cast<QTcpServer *>(sender());
+    Q_ASSERT(server);
+    while (server->hasPendingConnections()) {
+        QTcpSocket *socket = server->nextPendingConnection();
+
+        CoreAuthHandler *handler = new CoreAuthHandler(socket, this);
+        _connectingClients.insert(handler);
+
+        connect(handler, SIGNAL(disconnected()), SLOT(clientDisconnected()));
+        connect(handler, SIGNAL(socketError(QAbstractSocket::SocketError,QString)), SLOT(socketError(QAbstractSocket::SocketError,QString)));
+        connect(handler, SIGNAL(handshakeComplete(RemotePeer*,UserId)), SLOT(setupClientSession(RemotePeer*,UserId)));
+
+        quInfo() << qPrintable(tr("Client connected from"))  << qPrintable(socket->peerAddress().toString());
+
+        if (!_configured) {
+            stopListening(tr("Closing server for basic setup."));
+        }
     }
-  }
 }
 
+
 // Potentially called during the initialization phase (before handing the connection off to the session)
-void Core::clientDisconnected() {
-  QTcpSocket *socket = qobject_cast<QTcpSocket *>(sender());
-  if(socket) {
-    // here it's safe to call methods on socket!
-    quInfo() << qPrintable(tr("Non-authed client disconnected.")) << qPrintable(socket->peerAddress().toString());
-    blocksizes.remove(socket);
-    clientInfo.remove(socket);
-    socket->deleteLater();
-  } else {
-    // we have to crawl through the hashes and see if we find a victim to remove
-    qDebug() << qPrintable(tr("Non-authed client disconnected. (socket allready destroyed)"));
-
-    // DO NOT CALL ANY METHODS ON socket!!
-    socket = static_cast<QTcpSocket *>(sender());
-
-    QHash<QTcpSocket *, quint32>::iterator blockSizeIter = blocksizes.begin();
-    while(blockSizeIter != blocksizes.end()) {
-      if(blockSizeIter.key() == socket) {
-       blockSizeIter = blocksizes.erase(blockSizeIter);
-      } else {
-       blockSizeIter++;
-      }
-    }
-
-    QHash<QTcpSocket *, QVariantMap>::iterator clientInfoIter = clientInfo.begin();
-    while(clientInfoIter != clientInfo.end()) {
-      if(clientInfoIter.key() == socket) {
-       clientInfoIter = clientInfo.erase(clientInfoIter);
-      } else {
-       clientInfoIter++;
-      }
-    }
-  }
-
-
-  // make server listen again if still not configured
-  if (!_configured) {
-    startListening();
-  }
-
-  // TODO remove unneeded sessions - if necessary/possible...
-  // Suggestion: kill sessions if they are not connected to any network and client.
-}
-
-void Core::setupClientSession(QTcpSocket *socket, UserId uid) {
-  // Find or create session for validated user
-  SessionThread *sess;
-  if(sessions.contains(uid)) sess = sessions[uid];
-  else sess = createSession(uid);
-  // Hand over socket, session then sends state itself
-  disconnect(socket, 0, this, 0);
-  blocksizes.remove(socket);
-  clientInfo.remove(socket);
-  if(!sess) {
-    qWarning() << qPrintable(tr("Could not initialize session for client:")) << qPrintable(socket->peerAddress().toString());
-    socket->close();
-  }
-  sess->addClient(socket);
-}
-
-void Core::setupInternalClientSession(SignalProxy *proxy) {
-  if(!_configured) {
-    stopListening();
-    setupCoreForInternalUsage();
-  }
-
-  UserId uid = _storage->internalUser();
-
-  // Find or create session for validated user
-  SessionThread *sess;
-  if(sessions.contains(uid))
-    sess = sessions[uid];
-  else
-    sess = createSession(uid);
-  sess->addClient(proxy);
-}
-
-SessionThread *Core::createSession(UserId uid, bool restore) {
-  if(sessions.contains(uid)) {
-    qWarning() << "Calling createSession() when a session for the user already exists!";
-    return 0;
-  }
-  SessionThread *sess = new SessionThread(uid, restore, this);
-  sessions[uid] = sess;
-  sess->start();
-  return sess;
+void Core::clientDisconnected()
+{
+    CoreAuthHandler *handler = qobject_cast<CoreAuthHandler *>(sender());
+    Q_ASSERT(handler);
+
+    quInfo() << qPrintable(tr("Non-authed client disconnected:")) << qPrintable(handler->socket()->peerAddress().toString());
+    _connectingClients.remove(handler);
+    handler->deleteLater();
+
+    // make server listen again if still not configured
+    if (!_configured) {
+        startListening();
+    }
+
+    // TODO remove unneeded sessions - if necessary/possible...
+    // Suggestion: kill sessions if they are not connected to any network and client.
 }
 
-#ifdef HAVE_SSL
-void Core::sslErrors(const QList<QSslError> &errors) {
-  Q_UNUSED(errors);
-  QSslSocket *socket = qobject_cast<QSslSocket *>(sender());
-  if(socket)
-    socket->ignoreSslErrors();
+
+void Core::setupClientSession(RemotePeer *peer, UserId uid)
+{
+    CoreAuthHandler *handler = qobject_cast<CoreAuthHandler *>(sender());
+    Q_ASSERT(handler);
+
+    // From now on everything is handled by the client session
+    disconnect(handler, 0, this, 0);
+    _connectingClients.remove(handler);
+    handler->deleteLater();
+
+    // Find or create session for validated user
+    sessionForUser(uid);
+
+    // as we are currently handling an event triggered by incoming data on this socket
+    // it is unsafe to directly move the socket to the client thread.
+    QCoreApplication::postEvent(this, new AddClientEvent(peer, uid));
 }
-#endif
 
-void Core::socketError(QAbstractSocket::SocketError err) {
-  QAbstractSocket *socket = qobject_cast<QAbstractSocket *>(sender());
-  if(socket && err != QAbstractSocket::RemoteHostClosedError)
-    qWarning() << "Core::socketError()" << socket << err << socket->errorString();
+
+void Core::customEvent(QEvent *event)
+{
+    if (event->type() == AddClientEventId) {
+        AddClientEvent *addClientEvent = static_cast<AddClientEvent *>(event);
+        addClientHelper(addClientEvent->peer, addClientEvent->userId);
+        return;
+    }
 }
 
-bool Core::migrateBackend(const QString &backend) {
-  AbstractSqlStorage *sqlStorage = qobject_cast<AbstractSqlStorage *>(_storage);
-  if(!sqlStorage) {
-    qWarning() << "Core::migrateDb(): only SQL based backends can be migrated!";
-    return false;
-  }
 
-  AbstractSqlMigrationReader *reader = sqlStorage->createMigrationReader();
-  if(!reader) {
-    qWarning() << qPrintable(QString("Core::migrateDb(): unable to migrate storage backend! (No migration reader for %1)").arg(sqlStorage->displayName()));
-    return false;
-  }
+void Core::addClientHelper(RemotePeer *peer, UserId uid)
+{
+    // Find or create session for validated user
+    SessionThread *session = sessionForUser(uid);
+    session->addClient(peer);
+}
 
 
-  // reregister all storage backends
-  registerStorageBackends();
-  if(_storageBackends.contains(sqlStorage->displayName())) {
-    unregisterStorageBackend(_storageBackends[sqlStorage->displayName()]);
-  }
-  if(!_storageBackends.contains(backend)) {
-    qWarning() << qPrintable(QString("Core::migrateBackend(): unsupported migration target: %1").arg(backend));
-    qWarning() << "    supported Targets:" << qPrintable(QStringList(_storageBackends.keys()).join(", "));
-    return false;
-  }
+void Core::setupInternalClientSession(InternalPeer *clientPeer)
+{
+    if (!_configured) {
+        stopListening();
+        setupCoreForInternalUsage();
+    }
 
-  Storage *storage = _storageBackends[backend];
-  QVariantMap settings = promptForSettings(storage);
+    UserId uid;
+    if (_storage) {
+        uid = _storage->internalUser();
+    }
+    else {
+        quWarning() << "Core::setupInternalClientSession(): You're trying to run monolithic Quassel with an unusable Backend! Go fix it!";
+        return;
+    }
 
-  Storage::State storageState = storage->init(settings);
-  switch(storageState) {
-  case Storage::NotAvailable:
-    qCritical() << "Core::migrateBackend(): selected storage backend is not available:" << backend;
-    return false;
-  case Storage::NeedsSetup:
-    if(!storage->setup(settings)) {
-      qWarning() << qPrintable(QString("Core::migrateBackend(): unable to setup target: %1").arg(backend));
-      return false;
+    InternalPeer *corePeer = new InternalPeer(this);
+    corePeer->setPeer(clientPeer);
+    clientPeer->setPeer(corePeer);
+
+    // Find or create session for validated user
+    SessionThread *sessionThread = sessionForUser(uid);
+    sessionThread->addClient(corePeer);
+}
+
+
+SessionThread *Core::sessionForUser(UserId uid, bool restore)
+{
+    if (_sessions.contains(uid))
+        return _sessions[uid];
+
+    SessionThread *session = new SessionThread(uid, restore, strictIdentEnabled(), this);
+    _sessions[uid] = session;
+    session->start();
+    return session;
+}
+
+
+void Core::socketError(QAbstractSocket::SocketError err, const QString &errorString)
+{
+    quWarning() << QString("Socket error %1: %2").arg(err).arg(errorString);
+}
+
+
+QVariantList Core::backendInfo()
+{
+    instance()->registerStorageBackends();
+
+    QVariantList backendInfos;
+    for (auto &&backend : instance()->_registeredStorageBackends) {
+        QVariantMap v;
+        v["BackendId"]   = backend->backendId();
+        v["DisplayName"] = backend->displayName();
+        v["Description"] = backend->description();
+        v["SetupData"]   = backend->setupData(); // ignored by legacy clients
+
+        // TODO Protocol Break: Remove legacy (cf. authenticatorInfo())
+        const auto &setupData = backend->setupData();
+        QStringList setupKeys;
+        QVariantMap setupDefaults;
+        for (int i = 0; i + 2 < setupData.size(); i += 3) {
+            setupKeys << setupData[i].toString();
+            setupDefaults[setupData[i].toString()] = setupData[i + 2];
+        }
+        v["SetupKeys"]     = setupKeys;
+        v["SetupDefaults"] = setupDefaults;
+        // TODO Protocol Break: Remove
+        v["IsDefault"]     = (backend->backendId() == "SQLite"); // newer clients will just use the first in the list
+
+        backendInfos << v;
     }
+    return backendInfos;
+}
+
 
-    if(storage->init(settings) != Storage::IsReady) {
-      qWarning() << qPrintable(QString("Core::migrateBackend(): unable to initialize target: %1").arg(backend));
-      return false;
+QVariantList Core::authenticatorInfo()
+{
+    instance()->registerAuthenticators();
+
+    QVariantList authInfos;
+    for(auto &&backend : instance()->_registeredAuthenticators) {
+        QVariantMap v;
+        v["BackendId"]   = backend->backendId();
+        v["DisplayName"] = backend->displayName();
+        v["Description"] = backend->description();
+        v["SetupData"]   = backend->setupData();
+        authInfos << v;
     }
-  case Storage::IsReady:
-    break;
-  }
+    return authInfos;
+}
 
-  sqlStorage = qobject_cast<AbstractSqlStorage *>(storage);
-  if(!sqlStorage) {
-    qWarning() << "Core::migrateDb(): only SQL based backends can be migrated!";
-    return false;
-  }
-  AbstractSqlMigrationWriter *writer = sqlStorage->createMigrationWriter();
-  if(!writer) {
-    qWarning() << qPrintable(QString("Core::migrateDb(): unable to migrate storage backend! (No migration writer for %1)").arg(backend));
-    return false;
-  }
-
-  qDebug() << qPrintable(QString("Migrating Storage backend %1 to %2...").arg(_storage->displayName(), storage->displayName()));
-  delete _storage;
-  _storage = 0;
-  delete storage;
-  storage = 0;
-  if(reader->migrateTo(writer)) {
-    qDebug() << "Migration finished!";
-    saveBackendSettings(backend, settings);
+// migration / backend selection
+bool Core::selectBackend(const QString &backend)
+{
+    // reregister all storage backends
+    registerStorageBackends();
+    auto storage = storageBackend(backend);
+    if (!storage) {
+        QStringList backends;
+        std::transform(_registeredStorageBackends.begin(), _registeredStorageBackends.end(),
+                       std::back_inserter(backends), [](const DeferredSharedPtr<Storage>& backend) {
+                           return backend->displayName();
+                       });
+        quWarning() << qPrintable(tr("Unsupported storage backend: %1").arg(backend));
+        quWarning() << qPrintable(tr("Supported backends are:")) << qPrintable(backends.join(", "));
+        return false;
+    }
+
+    QVariantMap settings = promptForSettings(storage.get());
+
+    Storage::State storageState = storage->init(settings);
+    switch (storageState) {
+    case Storage::IsReady:
+        if (!saveBackendSettings(backend, settings)) {
+            qCritical() << qPrintable(QString("Could not save backend settings, probably a permission problem."));
+        }
+        quWarning() << qPrintable(tr("Switched storage backend to: %1").arg(backend));
+        quWarning() << qPrintable(tr("Backend already initialized. Skipping Migration..."));
+        return true;
+    case Storage::NotAvailable:
+        qCritical() << qPrintable(tr("Storage backend is not available: %1").arg(backend));
+        return false;
+    case Storage::NeedsSetup:
+        if (!storage->setup(settings)) {
+            quWarning() << qPrintable(tr("Unable to setup storage backend: %1").arg(backend));
+            return false;
+        }
+
+        if (storage->init(settings) != Storage::IsReady) {
+            quWarning() << qPrintable(tr("Unable to initialize storage backend: %1").arg(backend));
+            return false;
+        }
+
+        if (!saveBackendSettings(backend, settings)) {
+            qCritical() << qPrintable(QString("Could not save backend settings, probably a permission problem."));
+        }
+        quWarning() << qPrintable(tr("Switched storage backend to: %1").arg(backend));
+        break;
+    }
+
+    // let's see if we have a current storage object we can migrate from
+    auto reader = getMigrationReader(_storage.get());
+    auto writer = getMigrationWriter(storage.get());
+    if (reader && writer) {
+        qDebug() << qPrintable(tr("Migrating storage backend %1 to %2...").arg(_storage->displayName(), storage->displayName()));
+        _storage.reset();
+        storage.reset();
+        if (reader->migrateTo(writer.get())) {
+            qDebug() << "Migration finished!";
+            qDebug() << qPrintable(tr("Migration finished!"));
+            if (!saveBackendSettings(backend, settings)) {
+                qCritical() << qPrintable(QString("Could not save backend settings, probably a permission problem."));
+                return false;
+            }
+            return true;
+        }
+        quWarning() << qPrintable(tr("Unable to migrate storage backend! (No migration writer for %1)").arg(backend));
+        return false;
+    }
+
+    // inform the user why we cannot merge
+    if (!_storage) {
+        quWarning() << qPrintable(tr("No currently active storage backend. Skipping migration..."));
+    }
+    else if (!reader) {
+        quWarning() << qPrintable(tr("Currently active storage backend does not support migration: %1").arg(_storage->displayName()));
+    }
+    if (writer) {
+        quWarning() << qPrintable(tr("New storage backend does not support migration: %1").arg(backend));
+    }
+
+    // so we were unable to merge, but let's create a user \o/
+    _storage = std::move(storage);
+    createUser();
     return true;
-  }
-  return false;
 }
 
-bool Core::switchBackend(const QString &backend) {
-  if(!_storageBackends.contains(backend)) {
-    qWarning() << qPrintable(QString("Core::switchBackend(): unsupported backend: %1").arg(backend));
-    qWarning() << "    supported backends:" << qPrintable(QStringList(_storageBackends.keys()).join(", "));
-    return false;
-  }
+// TODO: I am not sure if this function is implemented correctly.
+// There is currently no concept of migraiton between auth backends.
+bool Core::selectAuthenticator(const QString &backend)
+{
+    // Register all authentication backends.
+    registerAuthenticators();
+    auto auther = authenticator(backend);
+    if (!auther) {
+        QStringList authenticators;
+        std::transform(_registeredAuthenticators.begin(), _registeredAuthenticators.end(),
+                       std::back_inserter(authenticators), [](const DeferredSharedPtr<Authenticator>& authenticator) {
+                           return authenticator->displayName();
+                       });
+        quWarning() << qPrintable(tr("Unsupported authenticator: %1").arg(backend));
+        quWarning() << qPrintable(tr("Supported authenticators are:")) << qPrintable(authenticators.join(", "));
+        return false;
+    }
+
+    QVariantMap settings = promptForSettings(auther.get());
+
+    Authenticator::State state = auther->init(settings);
+    switch (state) {
+    case Authenticator::IsReady:
+        saveAuthenticatorSettings(backend, settings);
+        quWarning() << qPrintable(tr("Switched authenticator to: %1").arg(backend));
+        return true;
+    case Authenticator::NotAvailable:
+        qCritical() << qPrintable(tr("Authenticator is not available: %1").arg(backend));
+        return false;
+    case Authenticator::NeedsSetup:
+        if (!auther->setup(settings)) {
+            quWarning() << qPrintable(tr("Unable to setup authenticator: %1").arg(backend));
+            return false;
+        }
 
-  Storage *storage = _storageBackends[backend];
-  QVariantMap settings = promptForSettings(storage);
+        if (auther->init(settings) != Authenticator::IsReady) {
+            quWarning() << qPrintable(tr("Unable to initialize authenticator: %1").arg(backend));
+            return false;
+        }
 
-  bool ok = initStorage(backend, settings, true /* initial setup is allowed */);
-  if(ok) {
-    saveBackendSettings(backend, settings);
-    qWarning() << "Switched backend to:" << qPrintable(backend);
-  } else {
-    qWarning() << "Failed to switch backend to:" << qPrintable(backend);
-  }
-  return ok;
-}
+        saveAuthenticatorSettings(backend, settings);
+        quWarning() << qPrintable(tr("Switched authenticator to: %1").arg(backend));
+    }
 
-void Core::saveBackendSettings(const QString &backend, const QVariantMap &settings) {
-  QVariantMap dbsettings;
-  dbsettings["Backend"] = backend;
-  dbsettings["ConnectionProperties"] = settings;
-  CoreSettings().setStorageSettings(dbsettings);
+    _authenticator = std::move(auther);
+    return true;
 }
 
-QVariantMap Core::promptForSettings(const Storage *storage) {
-  QVariantMap settings;
 
-  QStringList keys = storage->setupKeys();
-  if(keys.isEmpty())
-    return settings;
+bool Core::createUser()
+{
+    QTextStream out(stdout);
+    QTextStream in(stdin);
+    out << "Add a new user:" << endl;
+    out << "Username: ";
+    out.flush();
+    QString username = in.readLine().trimmed();
+
+    disableStdInEcho();
+    out << "Password: ";
+    out.flush();
+    QString password = in.readLine().trimmed();
+    out << endl;
+    out << "Repeat Password: ";
+    out.flush();
+    QString password2 = in.readLine().trimmed();
+    out << endl;
+    enableStdInEcho();
 
-  QTextStream out(stdout);
-  QTextStream in(stdin);
-  out << "!!!Warning: echo mode is always on even if asked for a password!!!" << endl;
-  out << "Default values are in brackets" << endl;
+    if (password != password2) {
+        quWarning() << "Passwords don't match!";
+        return false;
+    }
+    if (password.isEmpty()) {
+        quWarning() << "Password is empty!";
+        return false;
+    }
 
-  QVariantMap defaults = storage->setupDefaults();
-  QString value;
-  foreach(QString key, keys) {
-    QVariant val;
-    if(defaults.contains(key)) {
-      val = defaults[key];
+    if (_configured && _storage->addUser(username, password).isValid()) {
+        out << "Added user " << username << " successfully!" << endl;
+        return true;
+    }
+    else {
+        quWarning() << "Unable to add user:" << qPrintable(username);
+        return false;
     }
-    out << key;
-    if(!val.toString().isEmpty()) {
-      out << " (" << val.toString() << ")";
+}
+
+
+bool Core::changeUserPass(const QString &username)
+{
+    QTextStream out(stdout);
+    QTextStream in(stdin);
+    UserId userId = _storage->getUserId(username);
+    if (!userId.isValid()) {
+        out << "User " << username << " does not exist." << endl;
+        return false;
     }
-    out << ": ";
+
+    if (!canChangeUserPassword(userId)) {
+        out << "User " << username << " is configured through an auth provider that has forbidden manual password changing." << endl;
+        return false;
+    }
+
+    out << "Change password for user: " << username << endl;
+
+    disableStdInEcho();
+    out << "New Password: ";
+    out.flush();
+    QString password = in.readLine().trimmed();
+    out << endl;
+    out << "Repeat Password: ";
     out.flush();
-    value = in.readLine().trimmed();
+    QString password2 = in.readLine().trimmed();
+    out << endl;
+    enableStdInEcho();
+
+    if (password != password2) {
+        quWarning() << "Passwords don't match!";
+        return false;
+    }
+    if (password.isEmpty()) {
+        quWarning() << "Password is empty!";
+        return false;
+    }
 
-    if(!value.isEmpty()) {
-      switch(defaults[key].type()) {
-      case QVariant::Int:
-       val = QVariant(value.toInt());
-       break;
-      default:
-       val = QVariant(value);
-      }
+    if (_configured && _storage->updateUser(userId, password)) {
+        out << "Password changed successfully!" << endl;
+        return true;
+    }
+    else {
+        quWarning() << "Failed to change password!";
+        return false;
     }
-    settings[key] = val;
-  }
-  return settings;
 }
+
+
+bool Core::changeUserPassword(UserId userId, const QString &password)
+{
+    if (!isConfigured() || !userId.isValid())
+        return false;
+
+    if (!canChangeUserPassword(userId))
+        return false;
+
+    return instance()->_storage->updateUser(userId, password);
+}
+
+// TODO: this code isn't currently 100% optimal because the core
+// doesn't know it can have multiple auth providers configured (there aren't
+// multiple auth providers at the moment anyway) and we have hardcoded the
+// Database provider to be always allowed.
+bool Core::canChangeUserPassword(UserId userId)
+{
+    QString authProvider = instance()->_storage->getUserAuthenticator(userId);
+    if (authProvider != "Database") {
+        if (authProvider != instance()->_authenticator->backendId()) {
+            return false;
+        }
+        else if (instance()->_authenticator->canChangePassword()) {
+            return false;
+        }
+    }
+    return true;
+}
+
+
+std::unique_ptr<AbstractSqlMigrationReader> Core::getMigrationReader(Storage *storage)
+{
+    if (!storage)
+        return nullptr;
+
+    AbstractSqlStorage *sqlStorage = qobject_cast<AbstractSqlStorage *>(storage);
+    if (!sqlStorage) {
+        qDebug() << "Core::migrateDb(): only SQL based backends can be migrated!";
+        return nullptr;
+    }
+
+    return sqlStorage->createMigrationReader();
+}
+
+
+std::unique_ptr<AbstractSqlMigrationWriter> Core::getMigrationWriter(Storage *storage)
+{
+    if (!storage)
+        return nullptr;
+
+    AbstractSqlStorage *sqlStorage = qobject_cast<AbstractSqlStorage *>(storage);
+    if (!sqlStorage) {
+        qDebug() << "Core::migrateDb(): only SQL based backends can be migrated!";
+        return nullptr;
+    }
+
+    return sqlStorage->createMigrationWriter();
+}
+
+
+bool Core::saveBackendSettings(const QString &backend, const QVariantMap &settings)
+{
+    QVariantMap dbsettings;
+    dbsettings["Backend"] = backend;
+    dbsettings["ConnectionProperties"] = settings;
+    CoreSettings s = CoreSettings();
+    s.setStorageSettings(dbsettings);
+    return s.sync();
+}
+
+
+void Core::saveAuthenticatorSettings(const QString &backend, const QVariantMap &settings)
+{
+    QVariantMap dbsettings;
+    dbsettings["Authenticator"] = backend;
+    dbsettings["AuthProperties"] = settings;
+    CoreSettings().setAuthSettings(dbsettings);
+}
+
+// Generic version of promptForSettings that doesn't care what *type* of
+// backend it runs over.
+template<typename Backend>
+QVariantMap Core::promptForSettings(const Backend *backend)
+{
+    QVariantMap settings;
+    const QVariantList& setupData = backend->setupData();
+
+    if (setupData.isEmpty())
+        return settings;
+
+    QTextStream out(stdout);
+    QTextStream in(stdin);
+    out << "Default values are in brackets" << endl;
+
+    for (int i = 0; i + 2 < setupData.size(); i += 3) {
+        QString key = setupData[i].toString();
+        out << setupData[i+1].toString() << " [" << setupData[i+2].toString() << "]: " << flush;
+
+        bool noEcho = key.toLower().contains("password");
+        if (noEcho) {
+            disableStdInEcho();
+        }
+        QString input = in.readLine().trimmed();
+        if (noEcho) {
+            out << endl;
+            enableStdInEcho();
+        }
+
+        QVariant value{setupData[i+2]};
+        if (!input.isEmpty()) {
+            switch (value.type()) {
+            case QVariant::Int:
+                value = input.toInt();
+                break;
+            default:
+                value = input;
+            }
+        }
+        settings[key] = value;
+    }
+    return settings;
+}
+
+
+#ifdef Q_OS_WIN
+void Core::stdInEcho(bool on)
+{
+    HANDLE hStdin = GetStdHandle(STD_INPUT_HANDLE);
+    DWORD mode = 0;
+    GetConsoleMode(hStdin, &mode);
+    if (on)
+        mode |= ENABLE_ECHO_INPUT;
+    else
+        mode &= ~ENABLE_ECHO_INPUT;
+    SetConsoleMode(hStdin, mode);
+}
+
+#else
+void Core::stdInEcho(bool on)
+{
+    termios t;
+    tcgetattr(STDIN_FILENO, &t);
+    if (on)
+        t.c_lflag |= ECHO;
+    else
+        t.c_lflag &= ~ECHO;
+    tcsetattr(STDIN_FILENO, TCSANOW, &t);
+}
+
+#endif /* Q_OS_WIN */