//go:build darwin || freebsd || openbsd

package tun

import (
	"github.com/xjasonlyu/tun2socks/common/pool"
)

const (
	offset = 4 /* 4 bytes TUN_PI */

	defaultMTU = 1500
)

func (t *TUN) Read(packet []byte) (n int, err error) {
	buf := pool.Get(offset + len(packet))
	defer pool.Put(buf)

	if n, err = t.nt.Read(buf, offset); err != nil {
		return
	}

	copy(packet, buf[offset:offset+n])
	return
}

func (t *TUN) Write(packet []byte) (int, error) {
	buf := pool.Get(offset + len(packet))
	defer pool.Put(buf)

	copy(buf[offset:], packet)
	return t.nt.Write(buf[:offset+len(packet)], offset)
}