mssparms.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) 2012-2020 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_SSL_MSSPARMS_H
#define OPENVPN_SSL_MSSPARMS_H

#include <openvpn/common/options.hpp>
#include <openvpn/common/number.hpp>

namespace openvpn {
  struct MSSParms
  {
    enum {
      MSSFIX_DEFAULT = 1492,
    };

    void parse(const OptionList& opt, bool nothrow=false)
    {
      const Option *o = opt.get_ptr("mssfix");
      if (o)
	{
	  const std::string* val = o->get_ptr(1, 16);
	  if (val == nullptr)
	    {
	      if (nothrow)
		{
		  OPENVPN_LOG("Missing mssfix value, mssfix functionality disabled");
		  mssfix_default = false;
		  return;
		}
	      else
		throw option_error("mssfix must have a value");
	    }

	  const bool status = parse_number_validate<decltype(mssfix)>(*val,
								      16,
								      576,
								      65535,
								      &mssfix);
	  if (!status)
	    {
	      if (nothrow)
		{
		  // no need to warn if mssfix is actually 0
		  if (*val != "0")
		    {
		      OPENVPN_LOG("Invalid mssfix value " << *val << ", mssfix functionality disabled");
		      mssfix_default = false;
		    }
		}
	      else
		throw option_error("mssfix: parse/range issue");
	    }
	  else
	    {
	      mssfix_default = false;
	    }
	  mtu = (o->get_optional(2, 16) == "mtu");
	  fixed = (o->get_optional(2, 16) == "fixed");
	}
    }

    unsigned int mssfix = 0;    // standard OpenVPN mssfix parm
    bool mtu = false;           // include overhead from IP and TCP/UDP encapsulation
    bool fixed = false;         // use mssfix value without any encapsulation adjustments
    bool mssfix_default = true;
  };

  struct MSSCtrlParms
  {
    MSSCtrlParms(const OptionList& opt)
    {
      mssfix_ctrl = opt.get_num<decltype(mssfix_ctrl)>("mssfix-ctrl", 1, 1250,
						       256, 65535);
    }

    unsigned int mssfix_ctrl;
  };
}

#endif