/*
GoVPN -- simple secure free software virtual private network daemon
Copyright (C) 2014-2016 Sergey Matveev <stargrave@stargrave.org>

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

package govpn

import (
	"io"
	"strings"

	"github.com/pkg/errors"
	"github.com/songgao/water"
)

func newTAPer(ifaceName string) (io.ReadWriteCloser, error) {
	if !strings.HasPrefix(ifaceName, interfaceTun) {
		return nil, errors.Wrap(errUnsupportedInterface, ifaceName)
	}
	if ifaceName != interfaceTun {
		return nil, errors.Errorf("Darwin don't allow to set an interface name, only %q is supported", ifaceName)
	}
	output, err := water.New(water.Config{DeviceType: water.TUN})
	return output, errors.Wrap(err, "water.New")
}