[Click] SetIPChecksum standard element

[Ruetee Chitpranee]

Hi,

I have a doubt regarding SetIPChecksum standard element.
I test it with *test.click* configuration file (put it before
CheckIPHeader) and I got bad lengths error.
Why it returns error since input packet has network header, good header
length and good packet length?

SetIPChecksum: bad lengths



Packet *

SetIPChecksum::simple_action(Packet *p_in)

{

    if (WritablePacket *p = p_in->uniqueify()) {

         click_ip *ip;

         unsigned plen, hlen;



         if (!p->has_network_header())

             goto bad;

         plen = p->network_length();

         if (plen < sizeof(click_ip))

             goto bad;

         ip = p->ip_header();

         hlen = ip->ip_hl << 2;

         if (hlen < sizeof(click_ip) || hlen > plen)

             goto bad;



         ip->ip_sum = 0;

         ip->ip_sum = click_in_cksum((unsigned char *)ip, hlen);

         return p;



      bad:

         click_chatter("SetIPChecksum: bad lengths");

         p->kill();

    }

    return 0;

}

ref: test.click

InfiniteSource(DATA \<00 00 c0 ae 67 ef  00 00 00 00 00 00  08 00

45 00 00 28  00 00 00 00  40 11 77 c3  01 00 00 01

02 00 00 02  13 69 13 69  00 14 d6 41  55 44 50 20

70 61 63 6b  65 74 21 0a>, LIMIT 5, STOP true)

         -> Strip(14)

         //-> Align(4, 0)    // in case we're not on x86

         -> CheckIPHeader(BADSRC 18.26.4.255 2.255.255.255 1.255.255.255)

          -> Print(ok)

         -> Discard;

-- 
Ruetee C.