thank you Jan. I know, I'm not very respectful, sorry. I will carefully read your pdf. and only after the reading I uso this mailing list: i think that this is the way. Good book, Jan, great work. On Tue, Aug 31, 2010 at 8:35 PM, Jan Engelhardt <jengelh@xxxxxxxxxx> wrote: > On Tuesday 2010-08-31 20:26, Nicola Padovano wrote: > >>Hi guys! i know the skb_transport_header to grab the tcp header of a >>packet...so i can write: >>struct tcphdr *tcp_header1 = (struct >>tcphdr*)skb_transport_header(skb), where skb is a certain packet. >> >>now, studying some source code that i've found some days ago, i've seen this: >> >>struct tcphdr *tcp_header2 = (void*)ip_hdr(skb) + ip_hdrlen(skb); >> >>I immediately thought that the two lines were identical, but but I was >>mistaken...in fact if i write this: >> >>printk(KERN_INFO "diff: %d\n",(int)((void*)tcp_header2 - (void*)tcp_header1)); >> >>i see, "diff: 20" >> >>so my question is: what's the difference between the two code lines? > > > skb_transport_header is also explained in the PDF, especially when it > can not be used. > -- Nicola Padovano e-mail: nicola.padovano@xxxxxxxxx web: http://npadov.blogspot.com/ -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
