Bug in ExtendedSocketOptions: TCP_QUICKACK can't be set in linux due to incorrect syscall level

[Bruno Da Silva]

Thanks, @Alan and @Jaikiran :)

I'll set myself up to submit a patch and reply to this chain once one is
ready for review.

Bruno


On Wed, Jun 7, 2023 at 6:18 AM Jaikiran Pai <jai.forums2013 at gmail.com>
wrote:

> Hello Bruno,
>
> Alan has created the JBS issue to track this. In order to submit a
> patch, you can follow the guidelines that are available at
> https://openjdk.org/guide/
>
> -Jaikiran
>
> On 07/06/23 3:20 pm, Alan Bateman wrote:
> > On 07/06/2023 07:17, Bruno Da Silva wrote:
> >> Hi all,
> >>
> >> Random SWE here. I've found a bug in the LinuxSocketOptions.c native
> >> implementation of getting/setting quickack on a socket. When running
> >> strace, the socket option that is set is actually changing the
> >> SO_PRIORITY.
> >>
> >> This is because the syscall is incorrectly called with
> >> level=SO_SOCKET rather than level=SOL_TCP. You can see this in the
> >> openjdk implementation on line 92 and 105:
> >>
> https://github.com/openjdk/jdk/blob/a08c5cb3f1be7a20c8f955951d1605bb8b1c1aa4/src/jdk.net/linux/native/libextnet/LinuxSocketOptions.c#L92.
>
> >> It has existed since the original implementation in JDK-8145635.
> >>
> >> I believe the fix is to change both get/set syscalls like this:
> >> setsockopt(fd, SOL_SOCKET, TCP_QUICKACK, &optval, sizeof (optval));
> >> to
> >> setsockopt(fd, SOL_TCP, TCP_QUICKACK, &optval, sizeof (optval));
> >>
> >> The bug has existed since JDK 10 and I see it still exists in the
> >> most recent versions of Java. It was found and tested in JDK 11.
> >>
> >>
> >> As a non-contributor, I don't know of a way of submitting a patch or
> >> directly reporting this bug. Can someone provide guidance on where to
> >> take it from here?
> >>
> > Good find, I've created JDK-8309591 [1] to track it. Create a PR if
> > you want to run with this, otherwise someone else will need to pick
> > this up.
> >
> > -Alan
> >
> > [1] https://bugs.openjdk.org/browse/JDK-8309591
>
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