From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olivier MATZ <olivier.matz-pdR9zngts4EAvxtiuMwx3w@public.gmane.org>
Subject: Re: UDP Checksum
Date: Thu, 06 Nov 2014 17:15:00 +0100
Message-ID: <545B9E84.2090701@6wind.com>
References: <CAKfHP0WWCrftSR=z=jvUsHCLtTZdBwch0ZvadiLa9nMfcbpW-Q@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
To: Alex Markuze <alex-I7wstvAgZDk@public.gmane.org>, "dev-VfR2kkLFssw@public.gmane.org" <dev-VfR2kkLFssw@public.gmane.org>
Return-path: <dev-bounces-VfR2kkLFssw@public.gmane.org>
In-Reply-To: <CAKfHP0WWCrftSR=z=jvUsHCLtTZdBwch0ZvadiLa9nMfcbpW-Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request-VfR2kkLFssw@public.gmane.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev-VfR2kkLFssw@public.gmane.org>
List-Help: <mailto:dev-request-VfR2kkLFssw@public.gmane.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request-VfR2kkLFssw@public.gmane.org?subject=subscribe>
Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org
Sender: "dev" <dev-bounces-VfR2kkLFssw@public.gmane.org>

Hello,

On 11/06/2014 05:05 PM, Alex Markuze wrote:
> I'm seeing "UDP: bad checksum." messages(dmesg) for packets sent by my dpdk
> app to a socket on a remote machine.
> Looking at the packets the scum value is set, its just not what wireshark
> expects.
> 
> When sending I'm setting these fields in the egress packets.
> 
>         pkt->pkt.vlan_macip.f.l2_len = sizeof(struct ether_hdr);
> 
>         pkt->pkt.vlan_macip.f.l3_len = sizeof(struct ipv4_hdr);
> 
>         pkt->ol_flags |= (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK);
> //PKT_TX_OFFLOAD_MASK;

I think you need to do:

 pkt->pkt.vlan_macip.f.l2_len = sizeof(struct ether_hdr);
 pkt->pkt.vlan_macip.f.l3_len = sizeof(struct ipv4_hdr);
 pkt->ol_flags |= (PKT_TX_IP_CKSUM | PKT_TX_UDP_CKSUM);
 ipv4_hdr->hdr_checksum = 0;
 udp_hdr->dgram_cksum = 0;
 udp_hdr->dgram_cksum = get_ipv4_psd_sum(ipv4_hdr); /* see csumonly.c */


Regards,
Olivier