A fragmented TCP Reset packet can cause Hold flows in vrouter

[Vedamurthy Joshi]

R2.20 Build 112 Ubuntu 14.04 Juno multi-node

==============
From 219.14.75.3, send a TCP Reset (fragmented)

>>> send(fragment(IP(dst="20.1.1.4")/TCP(dport=8888, flags="R", sport=7777)/payload, fragsize=400))
...
Sent 3 packets.
>>>
==============
It creates a flow as below
root@nodek2:~# flow -l | grep -A2 "20.1.1.4:8888"
2548940<=>4015896 219.14.75.3:7777 20.1.1.4:8888 6 (1)
(K(nh):70, Action:F, Flags:, TCP:RD, S(nh):70, Stats:3/1118, SPort:53496)

--
4015896<=>2548940 20.1.1.4:8888 219.14.75.3:7777 6 (1)
(K(nh):70, Action:F, Flags:, TCP:, S(nh):21, Stats:0/0, SPort:56927)

root@nodek2:~#
==============
Send the same Reset packet again

>>> send(fragment(IP(dst="20.1.1.4")/TCP(dport=8888, flags="R", sport=7777)/payload, fragsize=400))
...
Sent 3 packets.
>>>
==============
Hold flows are seen now.

root@nodek2:~# flow -l | grep -A2 "20.1.1.4:8888"
2548940 219.14.75.3:7777 20.1.1.4:8888 6 (1)
(K(nh):70, Action:H, Flags:, TCP:, S(nh):0, Stats:1/250, SPort:0)

root@nodek2:~#

==============

[Anand H. Krishnan (anandhk)]

https://github.com/Juniper/contrail-vrouter/commit/d752dcfc645d2c38045f6a649c00e7fbf785dcc4

[Anand H. Krishnan (anandhk)]

For mainline

https://github.com/Juniper/contrail-vrouter/commit/7e8bbfd8c994ef5230d27ce67fd734d861edcb4b