actionthread.hpp

//    OpenVPN -- An application to securely tunnel IP networks
//               over a single port, with support for SSL/TLS-based
//               session authentication and key exchange,
//               packet encryption, packet authentication, and
//               packet compression.
//
//    Copyright (C) 2012-2022 OpenVPN Inc.
//
//    This program is free software: you can redistribute it and/or modify
//    it under the terms of the GNU Affero General Public License Version 3
//    as published by the Free Software Foundation.
//
//    This program is distributed in the hope that it will be useful,
//    but WITHOUT ANY WARRANTY; without even the implied warranty of
//    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//    GNU Affero General Public License for more details.
//
//    You should have received a copy of the GNU Affero General Public License
//    along with this program in the COPYING file.
//    If not, see <http://www.gnu.org/licenses/>.


#ifndef OPENVPN_COMMON_ACTIONTHREAD_H
#define OPENVPN_COMMON_ACTIONTHREAD_H

#include <thread>

#include <openvpn/common/rc.hpp>
#include <openvpn/common/action.hpp>
#include <openvpn/log/logthread.hpp>

namespace openvpn {

class ActionThread : public RC<thread_safe_refcount>
{
  public:
    typedef RCPtr<ActionThread> Ptr;

    struct Notify
    {
        virtual void action_thread_finished(const ActionThread *self, bool status) = 0;
    };

    ActionThread(openvpn_io::io_context &io_context_arg,
                 const ActionList::Ptr &action_list,
                 Notify *completion_handler_arg)
        : io_context(io_context_arg),
          thread(nullptr),
          actions(action_list),
          completion_handler(completion_handler_arg)
    {
        if (actions)
            thread = new std::thread(&ActionThread::thread_func, this);
    }

    void stop(const bool halt)
    {
        if (thread)
        {
            if (halt)
                actions->halt();
            thread->join();
            delete thread;
            thread = nullptr;
            // Necessary because no guarantee that completion_handler
            // obj will remain in scope during io_context.post delay.
            completion_handler = nullptr;
        }
    }

    virtual ~ActionThread()
    {
        stop(true);
    }

  private:
    void completion_post(bool status)
    {
        Notify *n = completion_handler;
        completion_handler = nullptr;
        if (n)
            n->action_thread_finished(this, status);
    }

    void thread_func()
    {
        Log::Context logctx(logwrap);
        bool status = false;
        try
        {
            OPENVPN_LOG("START THREAD...");
            status = actions->execute();
            OPENVPN_LOG("END THREAD");
        }
        catch (const std::exception &e)
        {
            OPENVPN_LOG("ActionThread exception: " << e.what());
        }
        openvpn_io::post(io_context, [self = Ptr(this), status]()
                         { self->completion_post(status); });
    }

    openvpn_io::io_context &io_context;
    std::thread *thread;
    ActionList::Ptr actions;       // actions to execute in child thread
    Notify *completion_handler;    // completion handler
    Log::Context::Wrapper logwrap; // used to carry forward the log context from parent thread
};

} // namespace openvpn

#endif