[LibOS] Handle IP_RECVERR socket option as a no-op

[boryspoplawski]

Description of the changes

This socket option allows for later retrieval of detailed error descriptions that happened on the socket. We do not support such retrieval, so allowing to set this option basically defers the moment the app notices that it's not supported from the call to setsockopt, to the moment the error condition actually happens (which might be never).

Fixes #673

How to test this PR?

Try running repro code from #673

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This change is 

[dimakuv]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion, not enough approvals from maintainers (1 more required) (waiting on @boryspoplawski)

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libos/src/net/ip.c line 285 at r1 (raw file):

        /* See the comment in `set_ipv4_option` for why we handle it this way. */
        return 0;
    }

Actually, you could just move this under the switch (optname) -- this will basically be just 2 lines of code.

I guess you don't want to call DkStreamAttributesQueryByHandle() unnecessarily, but on the other hand -- this setsockopt() is a rare operation, so we don't lose any performance on this. Not blocking though.

[mkow]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: all files reviewed, 1 unresolved discussion (waiting on @boryspoplawski)

[boryspoplawski]

Reviewable status: 0 of 1 files reviewed, all discussions resolved, not enough approvals from maintainers (2 more required), not enough approvals from different teams (1 more required, approved so far: ITL) (waiting on @dimakuv and @mkow)

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libos/src/net/ip.c line 285 at r1 (raw file):

Previously, dimakuv (Dmitrii Kuvaiskii) wrote…

Actually, you could just move this under the switch (optname) -- this will basically be just 2 lines of code.

I guess you don't want to call DkStreamAttributesQueryByHandle() unnecessarily, but on the other hand -- this setsockopt() is a rare operation, so we don't lose any performance on this. Not blocking though.

Done.

[dimakuv]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: all files reviewed, all discussions resolved, not enough approvals from maintainers (1 more required)

[mkow]

Reviewed 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved