On Wed, Oct 25, 2017 at 4:16 PM Yifeng Sun <[email protected]> wrote:
> I feel that unbound stands out in the available open source DNS resolver. > > Below is the summary for unbound: > * The actual resolving work is done by a background process or thread. A > background process or thread seems unavoidable. Linux's getaddrinfo_a > clones a thread similarly. > * It is ported on Linux, BSD, Windows, MacOS/X and Solaris/SPARC. This is > good because OVS runs on a large range of platforms. > * It complies to the standard, with optional DNSSEC support. Some of its > features may not be needed in our case. > * The unbound context is thread-safe. Its internal locks may bring some > overhead. But since the DNS resolving is not frequent in OVS, I suppose > this small overhead is not an issue. > > Unbound looks like a good option. Another option is to create a background > thread which processes DNS resolving requests from the main thread and > sends back the resulting events to the main thread. This method is quite > simple and straightforward. > > The above are what I got so far. Please give your thoughts, thanks a lot. > If portability to all of the systems you mentioned in your second bullet point is important, then you can rule out a couple of options: * getaddrinfo_a is a GNU extension and is only available with glibc * The resolver functions[1] are a BSD specification so they'd be available on most platforms, but not on Windows. I don't personally recommend these because of the need to manually parse the DNS responses you receive. That leaves two options: * Run a background thread uses getaddrinfo() to perform resolution. * Use a third-party library (like unbound). Of these two options, I feel like the third-party library is the better option. The only downside I can think of is the extra dependency for OVS. And as far as what third-party library to use, I was the one that suggested unbound in the first place, so obviously I'm fine with using it :) Mark [1] http://man7.org/linux/man-pages/man3/resolver.3.html > > Below is the link for original discussion: > https://mail.openvswitch.org/pipermail/ovs-dev/2017-August/337038.html > > > > On Wed, Oct 25, 2017 at 2:11 PM, Ben Pfaff <[email protected]> wrote: > >> Hello everyone, please allow me to introduce Yifeng Sun (CCed), who >> recently joined VMware's Open vSwitch team. I've asked Yifeng to start >> out by working on DNS support for Open vSwitch. Yifeng, can you tell us >> about what you've discovered so far, based on this thread from August >> that I'm reviving, and your tentative conclusions? >> >> Thanks, >> >> Ben. >> > > _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
