examples/ipsec-secgw: update incremental checksum

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@nxp.com>
Acked-by: Radu Nicolau <radu.nicolau@intel.com>

diff --git a/examples/ipsec-secgw/ipip.h b/examples/ipsec-secgw/ipip.h
index fb6a6fa4592c0adc08206e16b6d8c62180c8d4f4..13b8455c3ec6091923e0d3fa50e5646fc1bd3331 100644 (file)
--- 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;