dnat源码追踪(五）-再次reply

四.再次REPLY

数据包如下：

      src:S_L:80

      dst:C_W:xx

(1)到达G_L

    662                 *ctinfo = + ;

    399                 statusbit = ;

    400         else

    401                 statusbit = ;

    402

    403         /* Invert if this is reply dir. */

    404         if (dir == )

    405                 statusbit ^= ;

    406

所以statusbit=

 

(2)去G_W

路由之后，来到POSTROUTING

- > - - - >nf_nat_packet

    399                 statusbit = ;

 

    402

    403         /* Invert if this is reply dir. */

    404         if (dir == )

得到statusbit=

 408    if (ct-> & statusbit) {

    409                 struct ;

    410

    411                 /* We are aiming to look like inverse of other direction. */

    412                 (&target, &ct->[!dir].);

    413

    414                 if (!(target.., , 0, &target, ))

    415                         return ;

    416         }

target=invert(ct->tuplehash[orig].tuple);

     src：G_W:80

     dst:C_W:xx

进入manip_pkt;

    378         if ( == ) {

    379                 (&->, ->, target->..);

    380                 -> = target->..;

    381         } else {

 

于是ip数据包变成：

            src:G_W:80

            dst:C_W:xx

 

Over!