Drop the hand-rolled TLS client hello parser

[pimterry]

Our TLS code currently contains a custom parser for TLS client hellos hand-rolled in C++. This is complicated and a bit scary (which is why we have a separate fuzzer for it) and does extra work anytime it's used: OpenSSL already parses the hello, and this duplicates it, and adds checks throughout various other methods to support that. It's only required for a niche legacy feature (TLS session ids) that isn't even supported in TLS 1.3, but it makes up just under 10% of our TLS implementation (and ~15% of the TLS C++).

This parser exists because 'resumeSession' needs to support async lookups for session ids, on top of OpenSSL's SSL_CTX_sess_set_get_cb which is sync-only. We handled that by parsing out the session id ourselves, in advance, and passing through to OpenSSL when we were ready to answer synchronously.

Nowadays though (since OpenSSL 1.1.1) both OpenSSL & BoringSSL have an early ClientHello callback with suspend/resume support to handle this properly. This custom parser is redundant, and can be replaced by standard APIs in both backends.

We've previously talked about dropping this, over literally more than a decade, e.g. #1464 stopping using the parser to power SNI & OCSP, #1462 discussed dropping session ids completely to help us kill it, and #5774 trying to deprecate it away.

Nowadays it's much easier and we don't need any breaking changes at all. This PR deletes lots of code and switches to the modern mechanisms for this (separate impls for BoringSSL & OpenSSL). It drops the client hello parser & all related infrastructure, while preserving all the functionality. We could aim to drop session ids later anyway as a breaking change, but this makes them very cheap to keep in the meantime.

In addition, one of the new tests here covers a bug that this fixes en route: the hello parser silently dropped session events on fragmented hellos, which we now handle correctly instead for free. That fix should be the only externally visible change.

[nodejs-github-bot]

Review requested:

• @nodejs/crypto
• @nodejs/gyp
• @nodejs/net

[mcollina]

lgtm

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/75299/

[codecov]

Codecov Report

❌ Patch coverage is 87.30159% with 8 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.17%. Comparing base (41525ab) to head (5875e8e).
⚠️ Report is 18 commits behind head on main.

Files with missing lines	Patch %	Lines
src/crypto/crypto_tls.cc	87.03%	3 Missing and 4 partials ⚠️
src/crypto/crypto_tls.h	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64827      +/-   ##
==========================================
+ Coverage   90.16%   90.17%   +0.01%     
==========================================
  Files         746      743       -3     
  Lines      242660   242604      -56     
  Branches    45720    45697      -23     
==========================================
- Hits       218793   218774      -19     
+ Misses      15360    15352       -8     
+ Partials     8507     8478      -29     

Files with missing lines	Coverage Δ
lib/internal/tls/wrap.js	95.15% <100.00%> (+0.04%)	⬆️
src/crypto/crypto_context.cc	72.41% <100.00%> (+0.13%)	⬆️
src/crypto/crypto_context.h	100.00% <ø> (ø)
src/crypto/crypto_tls.h	82.35% <50.00%> (-4.32%)	⬇️
src/crypto/crypto_tls.cc	78.40% <87.03%> (+0.09%)	⬆️

... and 76 files with indirect coverage changes

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