Bind9 + TCP_FASTOPEN => no rndc

[Dimitry Andric]

On 27 Sep 2017, at 19:35, Christopher Sean Hilton <chris at vindaloo.com> wrote:
> 
> I'm trying to configure bind 9.11 as a nameserver on FreeBSD
> 11-STABLE. When the bind9 port compile it enables TCP_FASTOPEN but the
> changes haven't yet been baked into the GENERIC Kernel. I can't find a
> way to disable the use of TCP_FASTOPEN in bind at startup. Is the only
> way to fix this problem to build a new kernel with TCP_FASTOPEN
> enabled?

It looks like bind enables use of TCP_FASTOPEN whenever its configure
script finds the define in the system headers.  But it does not check
whether the functionality actually works with setsockopt.

In any case, the message is harmless noise, as any errors are ignored:

#if defined(ISC_PLATFORM_HAVETFO) && defined(TCP_FASTOPEN)
#ifdef __APPLE__
        backlog = 1;
#else
        backlog = backlog / 2;
        if (backlog == 0)
                backlog = 1;
#endif
        if (setsockopt(sock->fd, IPPROTO_TCP, TCP_FASTOPEN,
                       (void *)&backlog, sizeof(backlog)) < 0) {
                isc__strerror(errno, strbuf, sizeof(strbuf));
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "setsockopt(%d, TCP_FASTOPEN) failed with %s",
                                 sock->fd, strbuf);
                /* TCP_FASTOPEN is experimental so ignore failures */
        }
#endif

-Dimitry

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