On 7/25/24 05:18, Jun Wang via discuss wrote: > Hi,team. > I used hping3 to send IPv4 packets and found that the checksum > of the packet was incorrect when it carried the option field. After > analyzing the code, I discovered that our IP checksum calculation > does not consider the length of the options, leading to the > checksum error. Are we not considering the IP options on purpose, > or is there another consideration? > > Test command : > hping3 -c 1000 -1 -G 10.252.246.164 > > packet: > > 0000 58 53 c0 56 07 46 cc d8 1f 1b 7e 5e 81 00 00 5c > 0010 08 00 45 00 00 76 00 00 40 00 3d 11 5d 33 0a fc > 0020 e5 46 0a fc e5 05 e1 5c 12 b5 00 62 84 69 08 00 > 0030 00 00 00 00 64 00 02 7a 3b 9b c2 2a 58 53 c0 56 > 0040 07 60 08 00 4f 00 00 44 f0 e4 00 00 3e 01 7e 14 > 0050 0a fc f7 23 0a fc f6 a4 07 27 0c 01 02 03 04 0a > 0060 fc e9 fc 00 00 00 00 00 00 00 00 00 00 00 00 00 > 0070 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > 0080 08 00 3e 2f b9 d0 00 00 > > > Calculation method: > > ip->ip_csum = csum(ip, sizeof *ip); >
The only place where we calculate IP checksum from scratch must be the checksum offload code, i.e. dp_packet_ip_set_header_csum(). Are you using checksum offload? If so, I'd say it is a bug in the dp_packet_ip_set_header_csum() function. It should use the length from the ip header. In general, OVS doesn't actually support IP options. It doesn't parse them and doesn't act on them. But it should allow packets with options to pass through. Best regards, Ilya Maximets. _______________________________________________ discuss mailing list disc...@openvswitch.org https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
