fuzz: Enhance fuzzing capabilities with new chunked and boundary tests

[manunio]

Summary

• Add chunked-write fuzz variants for Base64Decoder and QuotedPrintableDecoder in fuzz_decoders.py to exercise decoder state across split inputs.
• Add a dedicated fuzz_multipart_parser.py target that drives MultipartParser directly with fuzz-generated boundaries, chunked writes, max_size enforcement, and invalid boundary construction.
• Add a dedicated fuzz_querystring.py target covering QuerystringParser with single writes, chunked writes, and max_size truncation; both strict and non-strict parsing modes.
• fuzz_form.py: replace Mock callbacks with real no-ops, add parse_multipart_raw (fuzz-generated boundary), parse_multipart_with_content_length, and parse_form_urlencoded_chunked via create_form_parser.
• Expand fuzz_options_header.py to cover bytes input, latin-1 decoded string input, and None input as separate sub-targets.
• Add ConsumeBool() helper to EnhancedDataProvider in helpers.py.
• Suppress logging noise in all fuzz files via logging.disable(logging.CRITICAL), this is generally recommended for fuzz performance improvements .

[Kludex]

You are the expert.

Let me know if I can merge it.

[manunio]

Yes please merge it.

[Kludex]

Thanks @manunio 🙏

Let's see https://github.com/Kludex/python-multipart/actions/runs/24344710532/job/71082324098 👀

[manunio]

Thanks @manunio 🙏

Let's see https://github.com/Kludex/python-multipart/actions/runs/24344710532/job/71082324098 👀

It failed because of sarif, will have to update cifuzz,
let me check.

[manunio]

Hopefully this will fix it: google/oss-fuzz#15352

[Kludex]

@manunio anything we can do to help in that PR?

[manunio]

@Kludex I’ve asked the other members for a review. In the meantime, I think it’s better to disable the sarif generation I have a proposed a pr here: #269. Unfortunately, I don't have a way to test this locally. I hope disabling it fixes the issue until the upstream fix is merged. If that doesn't work either, disabling cifuzz.yml altogether would be a good backup option.

[manunio]

@Kludex for commit 78e29ab and eb109cc i can see that cifuzz was passing and for 3e64f5f it was failing because of network issues..

270.2 Err:8 http://archive.ubuntu.com/ubuntu focal/main amd64 libtool all 2.4.6-14
270.2   Connection failed [IP: 185.125.190.81 80]
270.2 E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/main/libt/libtool/libtool_2.4.6-14_all.deb  Connection failed [IP: 185.125.190.81 80]
270.2 E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?