[PATCH] net/rte_net: fix inner L2 length for tunneled Ethernet packets

[Khadem Ullah]

Hi Ivan, 

No, it does not breaking testpmd or any other applications. 
Yes, the structure is correct in rte_net.h and comment as well.

You can run testpmd in rxonly mode and set verbose to 3, send the following packet from remote and you will observe the output as given below: 

pkt=Ether(src="04:3f:72:f3:7a:43",dst="C8:0A:A9:04:49:1A")/IP(src="19.168.1.1",dst="19.168.1.1")/UDP(dport=4789)/VXLAN(vni=4094)/Ether(dst="22:11:11:11:11:10")/IP(dst="19.168.1.1")/UDP()


port 0/queue 0: received 1 packets
  src=04:3F:72:F3:7A:43 - dst=C8:0A:A9:04:49:1A - pool=mb_pool_0 - type=0x0800 - length=92 - nb_segs=1 - hw ptype: L2_ETHER L3_IPV4_EXT_UNKNOWN L4_UDP  - sw ptype: L2_ETHER L3_IPV4 L4_UDP TUNNEL_VXLAN INNER_L2_ETHER INNER_L3_IPV4 INNER_L4_UDP  - l2_len=14 - l3_len=20 - l4_len=8 - tunnel_len=8 - inner_l2_len=30 - inner_l3_len=20 - inner_l4_len=8 - Destination UDP port=4789 - Receive queue=0x0
  ol_flags: RTE_MBUF_F_RX_L4_CKSUM_GOOD RTE_MBUF_F_RX_IP_CKSUM_GOOD RTE_MBUF_F_RX_OUTER_L4_CKSUM_UNKNOWN 

The length is 92 bytes which is correct but inner_l2_len=30 which is incorrect. According to standard, the following calculation is true of VXLAN header (50 bytes) and VXLAN packet size(92 bytes).

50-byte VXLAN header =(14-byte outer ethernet header + 20-byte outer IP header + 8-byte outer UDP header + 8-byte VXLAN header ) 

 92-bytes VXLAN packet size= (14-byte outer Ethernet header + 20-byte outer IP header + 8-byte outer UDP header + 8-byte VXLAN header )+ (14-byte inner Ethernet header + 20-byte inner IP header  + 8-byte inner UDP) 

This patch correct the inner_l2_len which is 14 bytes.