Hi Radu,
On 1/15/2018 8:10 PM, Nicolau, Radu wrote:
-----Original Message-----
From: Akhil Goyal [mailto:akhil.go...@nxp.com]
Sent: Monday, January 15, 2018 12:48 PM
To: dev@dpdk.org
Cc: De Lara Guarch, Pablo <pablo.de.lara.gua...@intel.com>;
hemant.agra...@nxp.com; Nicolau, Radu <radu.nico...@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.go...@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.
There would be unnecessary wastage of cycles. This way of updating the
checksum is implemented as per the RFC1141
https://tools.ietf.org/html/rfc1141
Do you see any issue in this way of updating the checksum?
-Akhil
