[PATCH 0/5] ALPN-based HTTP/2 service detection improvements

[Urval Kheni <kheniurval777 () gmail com>]

Hi,

This patch series introduces ALPN-based improvements to service detection
for TLS services.

It adds support for extracting the negotiated ALPN protocol and uses
"h2" as a conservative fallback signal to infer HTTP over TLS when
service detection fails.

This improves detection of HTTP/2-only services, which return binary
responses not recognized by existing probes.

The changes are structured as follows:

 1. Fix OpenSSL provider unload crash in NSE
 2. Add ALPN annotation and HTTP/2 hinting
 3. Add ALPN protocol offer and OpenSSL detection
 4. Refine implementation to avoid API changes
 5. Use ALPN "h2" as fallback for HTTP inference

Key properties:
- No changes to existing detection behavior
- No false positives observed (tested with IMAP, SMTP, FTPS)
- Graceful fallback when ALPN is unavailable

Tested against:
- Local OpenSSL servers (h2, http/1.1, no ALPN)
- Public endpoints (google.com, cloudflare.com)
- Non-HTTP TLS services

GitHub PR:
https://github.com/nmap/nmap/pull/3348

Thanks,
Urval Kheni

Attachment: 0002-service_scan-Add-ALPN-annotation-and-HTTP-2-hinting.patch
Description:

Attachment: 0001-nse-Fix-crash-in-OpenSSL-provider-unload-during-GC.patch
Description:

Attachment: 0003-nsock-build-Add-ALPN-protocol-offer-and-OpenSSL-dete.patch
Description:

Attachment: 0005-service_scan-Use-ALPN-h2-as-fallback-to-infer-HTTP-o.patch
Description:

Attachment: 0004-service_scan-Refine-ALPN-implementation-to-avoid-API.patch
Description:

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