Cannot parse QUIC ClientHello split into two packets

[sfionov]

Steps to reproduce:

1. Download latest Chromium snapshot from https://commondatastorage.googleapis.com/chromium-browser-snapshots/index.html?prefix=Mac_Arm/1260335/
2. Run Chromium --enable-quic --origin-to-force-quic-on=http3.is:443
3. See AGQuicProcessingUnit: Failed to parse ClientHello in log

[ameshkov]

Why do they split it?

We'll need this in v1.14 or later?

[sfionov]

@ameshkov They now send "post-quantum" X25519Kyber768Draft00 key (additional 1200+ bytes) in key_share extension along with usual X25519 key. Also, on sites with ECH, ClientHello is split due to ECH extension.

I think we may correct it in CL1.15