[LARTC] Port number problem

[LARTC] Port number problem

[Pham Viet Ha]

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Hello there,

I am just a newbie. I got a bug when modifying CBQ scheduler in Linux Kernel 2.4. I just want to get the soure and destination port number of the packet (TCP/UDP). I used ntohs(skb->h.th->dest) for the destination port number of a TCP packet. It doesn't work. The printed value is not correct (we used FTP, port 21 to test).

Did anyone meet the same issue? Please give me a hand.

Thanks so much in advance.

VietHa

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Re: [LARTC] Port number problem

[EGAL Vincent]

Pham Viet Ha wrote:

> Hello there,
>  
> I am just a newbie. I got a bug when modifying CBQ scheduler in Linux 
> Kernel 2.4. I just want to get the soure and destination port number 
> of the packet (TCP/UDP). I used ntohs(skb->h.th->dest) for the 
> destination port number of a TCP packet. It doesn't work. The printed 
> value is not correct (we used FTP, port 21 to test).
>  
> Did anyone meet the same issue? Please give me a hand.
>  
> Thanks so much in advance.
>  
> VietHa

hi,
should try something like this :

struct iphdr *iph = skb->nh.iph;
struct tcphdr *th;
if (!(iph->frag_off&htons(IP_MF|IP_OFFSET)) &&
(iph->protocol = IPPROTO_TCP))
{
       th = (struct tcphdr*)(((u32*)iph) + iph->ihl);         
                    if (ntohs(th->dest) = ....
}


-- 
Vincent EGAL
Email : egal@ipanematech.com



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