[dualtor-io] fix dualtor sniffer start slow issue

[lolyu]

Description of PR

Summary:
Fixes # (issue)

Type of change

• Bug fix
• Testbed and Framework(new/improvement)
• New Test case
  • Skipped for non-supported platforms
• Test case improvement

Back port request

• 202205
• 202305
• 202311
• 202405
• 202411
• 202505

Approach

What is the motivation for this PR?

Fix the dualtor io failure:

>       pytest_assert(len(failures) == 0, '\n' + '\n'.join(failures))
E       Failed:
E       Traffic on server 192.168.0.2 was disrupted prior to test start, missing 1 packets from the start of the packet flow
E       Traffic on server 192.168.0.4 was disrupted prior to test start, missing 1 packets from the start of the packet flow
E       Traffic on server 192.168.0.6 was disrupted prior to test start, missing 1 packets from the start of the packet flow

The issue is introduced by PR #18299.
The reason is that, the dualtor sniffer now listens to all dataplane interfaces on ptf (with prefix eth); for topo like dualtor-120, it has 128 dataplane interfaces, dualtor sniffer takes up to 10+ seconds to setup 128 sockets for those interfaces, which can takes up to 10+ seconds.

Signed-off-by: Longxiang Lyu lolv@microsoft.com

How did you do it?

As now scapy defaults to listen on conf.iface (on ptf, it is mgmt) and it will use socket.bind to bind to it, let's replace socket.bind with a dummy NOOP function, so the packet socket created will not listen to conf.iface anymore and it will capture packets from all interfaces.

How did you verify/test it?

On dualtor-120:

dualtor_io/test_normal_op.py::test_normal_op_downstream_upper_tor[active-standby]  PASSED                                                                                                                                                                               [100%]

========================================================================================================== 1 passed, 1 deselected, 2 warnings in 443.91s (0:07:23) ===========================================================================================================

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[mssonicbld]

/azp run

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).

[bingwang-ms]

Please double confirm it works when iface is empty. I remember I saw some issue earlier when using empty iface. The change looks good to me if it works

[lolyu]

Please double confirm it works when iface is empty. I remember I saw some issue earlier when using empty iface. The change looks good to me if it works

Yes, it is working if iface is empty.

root@de73a6e7fb07:~# python3
Python 3.7.3 (default, Mar 23 2024, 16:12:05)
[GCC 8.3.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from scapy.all import *
>>> packets = sniff()

^C>>> packets
<Sniffed: TCP:122 UDP:1 ICMP:65 Other:5>

[yyynini]

LGTM

[mssonicbld]

Cherry-pick PR to 202411: #18776

[mssonicbld]

Cherry-pick PR to 202505: #18783