On 11/16/2015 09:02 PM, Tom Herbert wrote:
On Mon, Nov 16, 2015 at 4:20 PM, Ben Greear <gree...@candelatech.com> wrote:
Hello!
I'm hacking on (my already hacked) pktgen, trying to get it to send TCP
frames.
And, having issues getting checksums to work properly.
I'm trying this:
struct iphdr *iph = ip_hdr(skb);
struct net_device *odev = pkt_dev->odev;
if (pkt_dev->flags & F_TCP) {
if (odev->features & NETIF_F_V4_CSUM) {
skb->ip_summed = CHECKSUM_PARTIAL;
} else {
skb->ip_summed = CHECKSUM_NONE;
}
skb->csum = 0;
__tcp_v4_send_check(skb, iph->saddr, iph->daddr);
I added an export so I could call that __tcp_v4_send_check method
w/out having to put a fake socket struct on the stack.
But, the receiving NIC reports 100% checksum failure, so obviously
I'm not doing it correct.
Any suggestions on what I might be doing wrong or the proper method(s)
to call?
It's really hard to tell what is happening without seeing the full
patch your using. Maybe you're not setting the TCP correctly or
transport header is not set right in skb.
Unfortunately, my pktgen has diverged significantly from upstream, so
a patch is probably not so useful.
The full pktgen.[ch] files are here:
http://www.candelatech.com/~greearb/patches/
If you look for 'F_TCP' you can find the pertinent bits
that I'm mucking with. I have changed it a bit since I last posted
the patch above...but still the receiving NIC is reporting 100%
csum failure, so I must still be doing something wrong.
I have also tweaked how UDP is done, but that seems to be working.
Thanks,
Ben
--
Ben Greear <gree...@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
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