feat(qlog): log version_information on client

[mxinden]

👋 Hi there

This is Max, first time contributor.

Let me know if this tiny pull request is of some help. Would appreciate a review and pointers to what to tackle next.

Thank you for QUIC support in Firefox!

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This commit adds support for the qlog version_information QUIC event on the client.

Depends on #1504

Depends on cloudflare/quiche#1684

Meta issue: #528

This commit does not add server-side support. I was unsure where to add the qlog::xxx call. With my limited knowledge of the code base, I would place it in the TransportParametersHandler, though as of today, it does not have access to the connection's NeqoQlog. Thoughts?

[martinthomson]

For the server, look in server.rs for fn accept_connection(...). That is where a new connection is handled. There shouldn't be a negotiated equivalent on the server, but the recording of failed version negotiation can be recorded.

For VN, you can make a call in fn process_input(...) right where it calls PacketBuilder::version_negotiation(...), which is where the Version Negotiation packet is sent. For that, you'll need to create a new QLog instance with self.create_qlog_trace(attempt_key). You will have to follow other code for that. I probably wouldn't bother trying to reduce the number of logging events from the same remote address and DCID, because that just creates a cleanup hazard.

That won't catch all cases, but enough.

[codecov-commenter]

Codecov Report

Attention: 21 lines in your changes are missing coverage. Please review.

Comparison is base (d1639a4) 87.61% compared to head (3f52896) 87.56%.

Files	Patch %	Lines
neqo-transport/src/qlog.rs	38.23%	21 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1505      +/-   ##
==========================================
- Coverage   87.61%   87.56%   -0.05%     
==========================================
  Files         117      117              
  Lines       37848    37841       -7     
==========================================
- Hits        33160    33135      -25     
- Misses       4688     4706      +18     

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[mxinden]

With #1547 merged, all outstanding comments are addressed. @martinthomson or @larseggert could either of you take another look?

[martinthomson]

I opened #1549 for the server side. I was waiting to see what you planned there, that's all.

[mxinden]

I opened #1549 for the server side. I was waiting to see what you planned there, that's all.

Sorry, badly communicated from my end. I prepared the server side in #1531.