Add a patch for scapy to fix fd leak issue in AsyncSniffer

[bingwang-ms]

Why I did it

This PR is to add a patch to fix potential fd leak issue in AsyncSniffer in scapy python library.
There are two fd leak scenarios.

1. When starting worker thread _run, if an interface is down, an OSError is thrown, and the sockets that have been created will be leaked as it never got a chance to be closed.
2. When stopping the worker thread, same error can happen when calling close. The sockets not closed will be leaked.

Test code:

from scapy.all import *
import time


sniffing_iface = ["PortChannel101", "PortChannel102", "PortChannel106", "PortChannel1024"]
sniffstring = "udp"

sniffer = None

def process_packet(packet):
    print("Got a packet {}".format(len(packet)))

while True:
    sniffer = AsyncSniffer(iface=sniffing_iface, filter=sniffstring, prn=process_packet, store=False)
    try:
        sniffer.start()
        RETRY = 30
        while RETRY >= 0 and not hasattr(sniffer, 'stop_cb'):
            time.sleep(0.1)
            RETRY -= 1
        if RETRY < 0:
            print("Sniffer failed to start")
        else:
            print("Sniffer started")
        try:
            sniffer.stop()
            time.sleep(1)
            print("Sniffer stopped")
        except:
            pass
    except:
        time.sleep(1)
        pass

Run above code while toggling portchannels on the device. The opened fd is increasing.

Work item tracking

• Microsoft ADO 29735068:

How I did it

Catch OSError when creating sockets, and catch any exception when closing socket to ensure all sockets are closed.

How to verify it

Verified by the testing code above. No fd leak happened.

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106
• 202111
• 202205
• 202211
• 202305
• 202311
• 202405

Tested branch (Please provide the tested image version)

The change is tested on 202311 and 202405 branches.

Description for the changelog

fix potential fd leak issue in AsyncSniffer in scapy python library.

Link to config_db schema for YANG module changes

No config change.

A picture of a cute animal (not mandatory but encouraged)

[bingwang-ms]

/azpw ms_conflict

[bingwang-ms]

/azpw ms_conflict

[mssonicbld]

Cherry-pick PR to 202405: #20719

[mssonicbld]

Cherry-pick PR to 202311: #20722