Use x/net/ipv4/6 to construct oob info when writing packets

[sudarshan-reddy]

Fixes #3275.

All Unit tests pass and existing unit tests in conn_oob_test.go already cover the use case addressed by this fix.

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[sudarshan-reddy]

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[codecov]

Codecov Report

Merging #3278 (e491b5c) into master (ebcd98e) will increase coverage by 0.22%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master    #3278      +/-   ##
==========================================
+ Coverage   85.47%   85.69%   +0.22%     
==========================================
  Files         132      132              
  Lines        9799     9775      -24     
==========================================
+ Hits         8375     8376       +1     
+ Misses       1048     1024      -24     
+ Partials      376      375       -1     

Impacted Files	Coverage Δ
conn_oob.go	71.88% <0.00%> (+11.35%)	⬆️
conn_windows.go	56.52% <0.00%> (ø)
internal/qtls/go117.go	58.33% <0.00%> (ø)
packet_handler_map.go	75.00% <0.00%> (+0.40%)	⬆️

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[marten-seemann]

Just wondering, did you check if this works on FreeBSD? (not a requirement for this PR to be merged)

[sudarshan-reddy]

I only verified that it did not break anything.

Unfortunately I don't have a freeBSD setup behind anycast. I'm going to set one up this weekend and can check this in a follow up. I propose if the PR is good, we can merge it but keep the issue open until I can test FreeBSD.

[marten-seemann]

Can you delete this constant? Note it’s defined a couple of times, for the different build architectures.

[sudarshan-reddy]

This one is still being used here: https://github.com/lucas-clemente/quic-go/blob/master/conn_oob.go#L174. I will delete it with my next PR that uses the x package also for reading OOB.

[sudarshan-reddy]

home/circleci/project/integrationtests/self/key_update_test.go:101 failed for go117 but passed for go116. Is this flakey?

[sudarshan-reddy]

@marten-seemann CI LGTM. You okay if I squash commits?

[marten-seemann]

Thank you!