Fix Missing ECH (0xfe0d) and ALPS (0x44cd) extensions

[12189108]

Fix missing ECH and ALPS extensions

• Replace SSL_client_hello_get1_extensions_present() with raw ClientHello parsing
• Capture all TLS extensions including ECH (0xfe0d) and ALPS (0x44cd)
• Add SCSV detection (TLS_EMPTY_RENEGOTIATION_INFO_SCSV)
• Implement QUIC CRYPTO frame reassembly for fragmented ClientHello
• Support both TLS and QUIC connections with complete extension visibility

Patch generated from nginx 1.28.1 source code

[vlvkobal]

Hi @12189108, Thanks for the fix!

Two quick questions on buffer safety:

1. QUIC (ngx_event_quic_ssl.c): The alloc is based on the header length, but memcpy is based on the incoming frame len. If a frame sends more data than the header claimed, isn't that an overflow?
2. ALPN (ngx_http_ssl_module.c): Is it safe to trust in[0] without checking inlen?

[vlvkobal]

Also, please update NGINX_VERSION.

[12189108]

@vlvkobal , Thanks for raising these security issues! Fixed:

QUIC overflow: added bounds check before memcpy to prevent frames from exceeding header's declared length. Truncates and logs alert on overflow.

ALPN overflow: This was introduced by a previous commit, not by me. Fixed by validating inlen > 0 before accessing in[0] and ensuring buffer has sufficient data (inlen >= alpn_len + 1).

Both fixes handle malformed input gracefully while maintaining compatibility.

Note: Patches have been regenerated against the latest nginx code.

[vlvkobal]

Could you add tests for the ECH and ALPS extensions?