linux-gen: pktio: dpdk: fix IPv4 csum calculation when l4 offset is n…

…ot set

IPv4 header contains length of the header and options in IHL field. It
can be used to replace L3 length calculation based on offsets.
This patch fixes bug: https://bugs.linaro.org/show_bug.cgi?id=3686.

Signed-off-by: Bogdan Pricope <bogdan.pricope@linaro.org>
Reviewed-and-tested-by: Matias Elo <matias.elo@nokia.com>
Reviewed-by: Bill Fischofer <bill.fischofer@linaro.org>
Signed-off-by: Maxim Uvarov <maxim.uvarov@linaro.org>

platform/linux-generic/pktio/dpdk.c

@@ -656,11 +656,7 @@ static inline void pkt_set_ol_tx(odp_pktout_config_opt_t *pktout_cfg,
 	if (!ipv4_chksum_pkt && !udp_chksum_pkt && !tcp_chksum_pkt)
 		return;
 
-	if (pkt_p->l4_offset == ODP_PACKET_OFFSET_INVALID)
-		return;
-
 	mbuf->l2_len = pkt_p->l3_offset - pkt_p->l2_offset;
-	mbuf->l3_len = pkt_p->l4_offset - pkt_p->l3_offset;
 
 	if (l3_proto_v4)
 		mbuf->ol_flags = PKT_TX_IPV4;
@@ -671,8 +667,14 @@ static inline void pkt_set_ol_tx(odp_pktout_config_opt_t *pktout_cfg,
 		mbuf->ol_flags |=  PKT_TX_IP_CKSUM;
 
 		((struct ipv4_hdr *)l3_hdr)->hdr_checksum = 0;
+		mbuf->l3_len = _ODP_IPV4HDR_IHL(*(uint8_t *)l3_hdr) * 4;
 	}
 
+	if (pkt_p->l4_offset == ODP_PACKET_OFFSET_INVALID)
+		return;
+
+	mbuf->l3_len = pkt_p->l4_offset - pkt_p->l3_offset;
+
 	l4_hdr = (void *)(mbuf_data + pkt_p->l4_offset);
 
 	if (udp_chksum_pkt) {