+/* Find the offset to L5. This is needed by enic TSO implementation.
+ * Return 0 if not a TCP packet or can't figure out the length.
+ */
+static inline uint8_t tso_header_len(struct rte_mbuf *mbuf)
+{
+ struct ether_hdr *eh;
+ struct vlan_hdr *vh;
+ struct ipv4_hdr *ip4;
+ struct ipv6_hdr *ip6;
+ struct tcp_hdr *th;
+ uint8_t hdr_len;
+ uint16_t ether_type;
+
+ /* offset past Ethernet header */
+ eh = rte_pktmbuf_mtod(mbuf, struct ether_hdr *);
+ ether_type = eh->ether_type;
+ hdr_len = sizeof(struct ether_hdr);
+ if (ether_type == rte_cpu_to_be_16(ETHER_TYPE_VLAN)) {
+ vh = rte_pktmbuf_mtod_offset(mbuf, struct vlan_hdr *, hdr_len);
+ ether_type = vh->eth_proto;
+ hdr_len += sizeof(struct vlan_hdr);
+ }
+
+ /* offset past IP header */
+ switch (rte_be_to_cpu_16(ether_type)) {
+ case ETHER_TYPE_IPv4:
+ ip4 = rte_pktmbuf_mtod_offset(mbuf, struct ipv4_hdr *, hdr_len);
+ if (ip4->next_proto_id != IPPROTO_TCP)
+ return 0;
+ hdr_len += (ip4->version_ihl & 0xf) * 4;
+ break;
+ case ETHER_TYPE_IPv6:
+ ip6 = rte_pktmbuf_mtod_offset(mbuf, struct ipv6_hdr *, hdr_len);
+ if (ip6->proto != IPPROTO_TCP)
+ return 0;
+ hdr_len += sizeof(struct ipv6_hdr);
+ break;
+ default:
+ return 0;
+ }
+
+ if ((hdr_len + sizeof(struct tcp_hdr)) > mbuf->pkt_len)
+ return 0;
+
+ /* offset past TCP header */
+ th = rte_pktmbuf_mtod_offset(mbuf, struct tcp_hdr *, hdr_len);
+ hdr_len += (th->data_off >> 4) * 4;
+
+ if (hdr_len > mbuf->pkt_len)
+ return 0;
+
+ return hdr_len;
+}
+