[dpdk-dev] [PATCH] examples/ipsec-secgw: update incremental checksum
Nicolau, Radu
radu.nicolau at intel.com
Mon Jan 15 15:40:05 CET 2018
> -----Original Message-----
> From: Akhil Goyal [mailto:akhil.goyal at nxp.com]
> Sent: Monday, January 15, 2018 12:48 PM
> To: dev at dpdk.org
> Cc: De Lara Guarch, Pablo <pablo.de.lara.guarch at intel.com>;
> hemant.agrawal at nxp.com; Nicolau, Radu <radu.nicolau at intel.com>
> Subject: Re: [PATCH] examples/ipsec-secgw: update incremental checksum
>
> On 1/15/2018 6:12 PM, Akhil Goyal wrote:
> > When TTL is decremented or ecn is updated in IP header before
> > forwarding the packet, checksum needs to be updated.
> >
> > In this patch an incremental checksum is added for ipv4 case.
> >
> > Signed-off-by: Akhil Goyal <akhil.goyal at nxp.com>
> > ---
> This patch is an update to a very old patch which was rejected earlier.
> http://dpdk.org/dev/patchwork/patch/16113/
>
> > examples/ipsec-secgw/ipip.h | 19 ++++++++++++++++++-
> > 1 file changed, 18 insertions(+), 1 deletion(-)
> >
> > diff --git a/examples/ipsec-secgw/ipip.h b/examples/ipsec-secgw/ipip.h
> > index fb6a6fa..13b8455 100644
> > --- a/examples/ipsec-secgw/ipip.h
> > +++ b/examples/ipsec-secgw/ipip.h
> > @@ -27,6 +27,10 @@ ipip_outbound(struct rte_mbuf *m, uint32_t offset,
> uint32_t is_ipv6,
> > if (inip4->ip_v == IPVERSION) {
> > /* XXX This should be done by the forwarding engine instead
> */
> > inip4->ip_ttl -= 1;
> > + if (inip4->ip_sum >= rte_cpu_to_be_16(0xffff - 0x100))
> > + inip4->ip_sum += rte_cpu_to_be_16(0x100) + 1;
> > + else
> > + inip4->ip_sum += rte_cpu_to_be_16(0x100);
> > ds_ecn = inip4->ip_tos;
> > } else {
> > inip6 = (struct ip6_hdr *)inip4;
> > @@ -95,8 +99,17 @@ ip6ip_outbound(struct rte_mbuf *m, uint32_t offset,
> > static inline void
> > ip4_ecn_setup(struct ip *ip4)
> > {
> > - if (ip4->ip_tos & IPTOS_ECN_MASK)
> > + if (ip4->ip_tos & IPTOS_ECN_MASK) {
> > + unsigned long sum;
> > + uint8_t old;
> > +
> > + old = ip4->ip_tos;
> > ip4->ip_tos |= IPTOS_ECN_CE;
> > + sum = old + (~(*(uint8_t *)&ip4->ip_tos) & 0xff);
> > + sum += rte_be_to_cpu_16(ip4->ip_sum);
> > + sum = (sum & 0xffff) + (sum >> 16);
> > + ip4->ip_sum = rte_cpu_to_be_16(sum + (sum >> 16));
> > + }
> > }
> >
> > static inline void
> > @@ -140,6 +153,10 @@ ipip_inbound(struct rte_mbuf *m, uint32_t offset)
> > ip4_ecn_setup(inip4);
> > /* XXX This should be done by the forwarding engine instead
> */
> > inip4->ip_ttl -= 1;
> > + if (inip4->ip_sum >= rte_cpu_to_be_16(0xffff - 0x100))
> > + inip4->ip_sum += rte_cpu_to_be_16(0x100) + 1;
> > + else
> > + inip4->ip_sum += rte_cpu_to_be_16(0x100);
> > m->packet_type &= ~RTE_PTYPE_L4_MASK;
> > if (inip4->ip_p == IPPROTO_UDP)
> > m->packet_type |= RTE_PTYPE_L4_UDP;
> >
I think instead of manipulating the checksum in this way it will be better to use rte_ipv4_cksum to re-compute it, unless the performance penalty is too significant.
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