Re: questions on ip_input.c

[aksingh@xxxxxxxxxxx]

hi,

  sizeof(struct iphdr) can be different from iph->ihl*4, one difference is
this

HTH
Amit




"bunty " <bunty123_4@xxxxxxxxxxxxxx>@nl.linux.org on 06/03/2004 08:38:04 PM

Please respond to "bunty " <bunty123_4@xxxxxxxxxxxxxx>

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Subject:    questions on ip_input.c



hello ,

what is the difference between following two fragments of code?
---------------------------------------------------------------
 if (!pskb_may_pull(skb, sizeof(struct iphdr)))
  goto inhdr_error;

 iph = skb->nh.iph;
-----------------------------------------------------------------
 if (!pskb_may_pull(skb, iph->ihl*4))
  goto inhdr_error;

 iph = skb->nh.iph;
-----------------------------------------------------------------

Also

 /* Our transport medium may have padded the buffer out. Now we know it
                 * is IP we can trim to the true length of the frame.
                 * Note this now means skb->len holds ntohs(iph->tot_len).
                 */
                if (skb->len > len) {
                        __pskb_trim(skb, len);
                        if (skb->ip_summed == CHECKSUM_HW)
                                skb->ip_summed = CHECKSUM_NONE;

can anybody explain me in which condition trim is required ot transport
layer
to pad zeros?

regards,
parag.



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