//    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/>.

#ifndef OPENVPN_TRANSPORT_ALTPROXY_H
#define OPENVPN_TRANSPORT_ALTPROXY_H

#include <string>

#include <openvpn/common/rc.hpp>
#include <openvpn/transport/client/transbase.hpp>
#include <openvpn/transport/socket_protect.hpp>
#include <openvpn/client/remotelist.hpp>
#include <openvpn/crypto/digestapi.hpp>

namespace openvpn {
  struct AltProxy : public RC<thread_unsafe_refcount>
  {
    struct Config
    {
      Config()
	: free_list_max_size(8),
	  socket_protect(nullptr)
      {}

      RemoteList::Ptr remote_list;
      size_t free_list_max_size;
      Frame::Ptr frame;
      SessionStats::Ptr stats;

      RandomAPI::Ptr rng;
      DigestFactory::Ptr digest_factory;

      SocketProtect* socket_protect;
    };

    typedef RCPtr<AltProxy> Ptr;

    // return proxy name
    virtual std::string name() const = 0;

    // called to indicate whether or not remote_list should be cached
    virtual void set_enable_cache(const bool enable_cache) = 0;

    // return a RemoteList::Ptr (optional) to precache it
    virtual void precache(RemoteList::Ptr& r) = 0;

    // iterate to next host in proxy-specific remote_list, return true
    // to prevent next() from being called on global remote_list
    virtual bool next() = 0;

    // return true if this proxy method only supports TCP transport
    virtual bool requires_tcp() const = 0;

    // return a new TransportClientFactory for this proxy
    virtual TransportClientFactory::Ptr new_transport_client_factory(const Config&) = 0;
  };
}

#endif