//    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) 2012-2020 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/>.

// Abstract base classes for server tun objects

#ifndef OPENVPN_TUN_SERVER_TUNBASE_H
#define OPENVPN_TUN_SERVER_TUNBASE_H

#include <string>

#include <openvpn/common/exception.hpp>
#include <openvpn/common/rc.hpp>
#include <openvpn/common/function.hpp>
#include <openvpn/buffer/buffer.hpp>
#include <openvpn/server/servhalt.hpp>

namespace openvpn {
  namespace TunClientInstance {

    typedef Function<void(int fd)> PostCloseFunc;

    // A native reference to a client instance
    struct NativeHandle
    {
      NativeHandle() {}

      NativeHandle(const int fd_arg, const int peer_id_arg)
	: fd(fd_arg),
	  peer_id(peer_id_arg)
      {
      }

      bool fd_defined() const
      {
	return fd >= 0;
      }

      bool defined() const
      {
	return fd >= 0 && peer_id >= 0;
      }

      int fd = -1;
      int peer_id = -1;
    };

    // Base class for the client instance receiver.  Note that all
    // client instance receivers (transport, routing, management,
    // etc.) must inherit virtually from RC because the client instance
    // object will inherit from multiple receivers.
    struct Recv : public virtual RC<thread_unsafe_refcount>
    {
      typedef RCPtr<Recv> Ptr;

      //virtual bool defined() const = 0;
      virtual void stop() = 0;

      // Called with IP packets from tun layer.
      virtual void tun_recv(BufferAllocated& buf) = 0;

      // push a halt or restart message to client
      virtual void push_halt_restart_msg(const HaltRestart::Type type,
					 const std::string& reason,
					 const bool tell_client) = 0;
    };

    // Base class for the per-client-instance state of the TunServer.
    // Each client instance uses this class to send data to the tun layer.
    struct Send : public virtual RC<thread_unsafe_refcount>
    {
      typedef RCPtr<Send> Ptr;

      //virtual bool defined() const = 0;
      virtual void stop() = 0;

      virtual bool tun_send_const(const Buffer& buf) = 0;
      virtual bool tun_send(BufferAllocated& buf) = 0;

      // get the native handle for tun/peer
      virtual NativeHandle tun_native_handle() = 0;

      // set up relay to target
      virtual void relay(const IP::Addr& target, const int port) = 0;

      virtual const std::string& tun_info() const = 0;
    };

    // Factory for server tun object.
    struct Factory : public RC<thread_unsafe_refcount>
    {
      typedef RCPtr<Factory> Ptr;

      virtual Send::Ptr new_obj(Recv* parent) = 0;
    };

  }
}

#endif