[mpls-linux-general] regarding sk_buff structure....

[<vvk...@hs...>]

Hi  Experts !

     I have come across with one problem that , i want to get the packet  and
send it to an application ,
running in user space ..........  My objective is to get the  SHIM ,src,dest
address and packet data ........

  I am following  style.......................of code.

#define MPLS_MAX_BUFF_SIZE   1500
#define MPLS_MAX_DATA_SIZE   1500 - 4* sizeof ( unsigned long ) -1

int  mpls_get_packet_data( struct sk_buff *skb,    unsigned long shim,
                  int type )
{
   char        *fname="mpls_get_packet_data";
   mpls_info_t *buff=NULL;

      printk(KERN_ALERT"%s : entering .....\n",fname);

      buff=(mpls_info_t *)kmalloc(sizeof(mpls_info_t), GFP_KERNEL);
      if ( buff == NULL )
      {
         printk(KERN_ALERT"%s: kmalloc error",fname);
         return -ENOMEM;
      }

      if ( skb == NULL )
      {
         printk(KERN_ALERT"%s: skb NULL argument error",fname);
         kfree(buff);
         return -EINVAL;
      }

      /* Now get the  "src", "fec ..i.e dest address",
       * "data" from sk_buff structure .........
       * Fill it in the "mpls_info_t" structure...
       * and place the msg in the queue .......
       */


       buff->type = type;  /* Label Type ...IN or OUT Label */
       buff->shim = shim;  /* fill the SHIM info .......*/
       buff->src  = skb->nh.iph->saddr;  /* src address from sk_buff */
       buff->fec  = skb->nh.iph->daddr;  /* dest address from sk_buff */
       memset(buff->data, 0, MPLS_MAX_DATA_SIZE-1);

       if ( skb->data != NULL )
       {
             printk(KERN_ALERT"%s: skb data length [%d]\n",fname,skb->len);
             memcpy(buff->data, skb->data, skb->len);
       }

       return mpls_sendmsg(buff, MPLS_MAX_BUFF_SIZE);
 }

This function i am calling in the "mpls_output2"  function in the file :  "
mpls_output.c" file of mpls
src for kinux............

here problem is .........  after some time  kernel  panic msg arriving and
system is hanging up ....
no response ............    Error is : invalid operand : 00000

Is the way i am following is correct or not ?
Can  you  please guide me , how to retrieve the data............from  "sk_buff"
structure ...............?

Please guide me in this ..............

I am following the Linux Device Drivers book by oerilly .. by alessandro
rubini............

Thanks in advance........
Regards,Ramki kvv.

Hughes Software Systems