On Thursday, March 7, 2002, at 02:05 AM, Kshitij Gunjikar wrote:
> Hi All,
> Hi I'm studying code for ICMP .
>
> there is a piece of code in icmp_input which just returns when we find
> the
> ICMP packet length lesser than allowed.
>
> if (icmplen < ICMP_MINLEN) {
> icmpstat.icps_tooshort++;
> goto freeit;
> }
> i = hlen + min(icmplen, ICMP_ADVLENMIN);
> if (m->m_len < i && (m = m_pullup(m, i)) == 0) {
> icmpstat.icps_tooshort++;
> return;
> }
> where #define ICMPADVELMIN (8 + sizeof(struct ip) + 8)
> and icmplen = ip->ip_len ;
>
>
> why the return? Shouldn't there be a freeing of the msg.i.e call the
> m_freem(m) instead of return ?
If you look at the last 'if' statement, you'll notice that the call to
m_pullup() has returned NULL, which means that the mbuf has been freed
already (or, in any case, at this point in the code, there is no mbuf to
free, due to the assignment).
Regards,
Justin
--
Justin C. Walker, Curmudgeon-At-Large *
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| Only outlaws will have
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