[ech] fuzzing ECH (Was: Re: ECH PR reviews...)

[Stephen Farrell]

Hiya,

I'm doing a bit more work on that now. Found and fixed a few
input decoding things on the client, which is great, but it
doesn't look like the fuzzing is going very "deep." Seems a
bit better in that respect on the server side (as I'm injecting
some HPKE-related structure as discussed before) but I've not
found any new bugs on that side so far.

Does anyone have/know-of a published corpus that'd help the
fuzzer explore the space of ClientHello messages better, or
even code for a structure-aware thing (a la [1]) that knows TLS
presentation syntax?

Thanks,
S.

PS: After I've explored this some more and landed somewhere
with it, I plan to push another commit with all those changes to
the ECH-PR rather than have each fuzzing addition and bug fix in
separate commits.

[1] 
https://github.com/google/fuzzing/blob/master/docs/structure-aware-fuzzing.md
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