Bug:bfd_responder crash when process partial packet sent by itself

[baorliu]

Is it platform specific

generic

Importance or Severity

Critical

Description of the bug

These 2 cases may cause BFD related mgmt test fails:
bfd responder can receive the packet it sent. and at the time of restart, partial packet could be process and cause it crash:

Traceback (most recent call last):
  File "/opt/bfd_responder.py", line 205, in <module>
    main()
  File "/opt/bfd_responder.py", line 200, in main
    p.poll()
  File "/opt/bfd_responder.py", line 80, in poll
    self.responder.action(self.mapping[handler])
  File "/opt/bfd_responder.py", line 92, in action
    data)
  File "/opt/bfd_responder.py", line 127, in extract_bfd_info
    bfdpkt = BFD(ether.payload.payload.payload.load)
  File "/usr/local/lib/python2.7/dist-packages/scapy/packet.py", line 1070, in __getattr__
    raise AttributeError, attr

And also bfd responder initialize it's packet when receive DOWN bfd packet. In the case of bfd_responder restart and it get BFD UP packet, the packet become uninitialized, it cause socket sending packet error:

Traceback (most recent call last):
  File "/opt/bfd_responder.py", line 224, in <module>
    main()
  File "/opt/bfd_responder.py", line 219, in main
    p.poll()
  File "/opt/bfd_responder.py", line 81, in poll
    self.responder.action(self.mapping[handler])
  File "/opt/bfd_responder.py", line 106, in action
    interface.send(session["pkt"])
  File "/opt/bfd_responder.py", line 60, in send
    scapy2.sendp(data, iface=self.iface)
  File "/usr/local/lib/python2.7/dist-packages/scapy/sendrecv.py", line 259, in sendp
    __gen_send(conf.L2socket(iface=iface, *args, **kargs), x, inter=inter, loop=loop, count=count, verbose=verbose, realtime=realtime)
  File "/usr/local/lib/python2.7/dist-packages/scapy/sendrecv.py", line 234, in __gen_send
    s.send(p)
  File "/usr/local/lib/python2.7/dist-packages/scapy/supersocket.py", line 35, in send
    return self.outs.send(sx)
socket.error: [Errno 22] Invalid argument

Steps to Reproduce

using a python script craft bfd packet:
send an incomplete BFD packet or send UP state BFD packet to bfd_responder can trigger the issue.

Actual Behavior and Expected Behavior

1, for partial packet just ignore the packet.
2, for the UP BFD packet right after bfd_responder start or restart, ignore the packet per RFC5880 FSM.
treat the bfd_responder in DOWN state by default right after start or restart.

Relevant log output

Traceback (most recent call last):
  File "/opt/bfd_responder.py", line 224, in <module>
    main()
  File "/opt/bfd_responder.py", line 219, in main
    p.poll()
  File "/opt/bfd_responder.py", line 81, in poll
    self.responder.action(self.mapping[handler])
  File "/opt/bfd_responder.py", line 106, in action
    interface.send(session["pkt"])
  File "/opt/bfd_responder.py", line 60, in send
    scapy2.sendp(data, iface=self.iface)
  File "/usr/local/lib/python2.7/dist-packages/scapy/sendrecv.py", line 259, in sendp
    __gen_send(conf.L2socket(iface=iface, *args, **kargs), x, inter=inter, loop=loop, count=count, verbose=verbose, realtime=realtime)
  File "/usr/local/lib/python2.7/dist-packages/scapy/sendrecv.py", line 234, in __gen_send
    s.send(p)
  File "/usr/local/lib/python2.7/dist-packages/scapy/supersocket.py", line 35, in send
    return self.outs.send(sx)
socket.error: [Errno 22] Invalid argument

Output of show version

Attach files (if any)

No response

[baorliu]

#17419