[enhancement] Async Pcap(Ng)Reader implementations

[calligraf0]

Hi, first time opening an issue hope I do everything right 😃 , I choose not to go for the issue template as it seemed out of context for this since it's not a bug but a proposal.

Intro

As for the current state of Scapy there is no async-aware implementation for the PcapReader/PcapNgReader classes which may instead be useful when parsing many large .pcap* files using Scapy.

Solution?

I am not too familiar with the codebase but I tried to put together a horribly hacked version of possible implementation: at https://github.com/calligraf0/scapy/tree/async-pcap-reader (there is also a junkyard.py file which contains a "benchmark" which currently still lags behind the multithread sync implementation)

The main limitations I stumbled across right now are:

• this obviously requires a python version which supports asyncio
• lack of gzip support (the code I smashed together currently does not handle gzip compressed files, as I couldn't find a valid "drop in replacement" for gzip which supports async)
• pcap/cap only support (I only implemented the bare minimum, so no PcapNgReader for now)
• ugly defer of header parsing on first packet read (because of async, I couldn't use aiofiles in the __init__ method, a possible solution could be using the AsyncMixin class / rework the way the file is handled?)
• I am not a great programmer 😅 (that has no immediate solution 😝 )

Questions

• Is this a valid/interesting enhancement proposal? If so, is the solution I PoC'ed together a viable way (providing an extra class AsyncPcapReader instead of modifying the RawPcapReader class to also support async)?
• I am happy to try give this a better shot, are there any pointers on what to improve/rework?