Re: [Qemu-trivial] [PATCH] util/qemu-sockets: improve ai_flag hints for ipv6 hosts

[Michael Tokarev <mjt@tls.msk.ru>]

21.05.2015 15:33, Wolfgang Bumiller wrote:
> *) Do not use AI_ADDRCONFIG on listening sockets, because this flag
> makes it impossible to explicitly listen on '127.0.0.1' if no global
> ipv4 address is configured additionally, making this a very
> uncomfortable option.
> *) Add AI_V4MAPPED hint for connecting sockets.
> 
> If your system is globally only connected via ipv6 you often still want
> to be able to use '127.0.0.1' and 'localhost' (even if localhost doesn't
> also have an ipv6 entry).
> For example, PVE - unless explicitly asking for insecure mode - uses
> ipv4 loopback addresses with QEMU for live migrations tunneled over SSH.
> These fail to start because AI_ADDRCONFIG makes getaddrinfo refuse to
> work with '127.0.0.1'.
> 
> As for the AI_V4MAPPED flag: glibc uses it by default, and providing
> non-0 flags removes it. I think it makes sense to use it.
> 
> I also want to point out that glibc explicitly sidesteps POSIX standards
> when passing 0 as hints by then assuming both AI_V4MAPPED and
> AI_ADDRCONFIG (the latter being a rather weird choice IMO), while
> according to POSIX.1-2001 it should be assumed 0. (glibc considers its
> choice an improvement.)
> Since either AI_CANONNAME or AI_PASSIVE are passed in our cases, glibc's
> default flags in turn are disabled again unless explicitly added, which
> I do with this patch.

Applied (finally!) to -trivial.  I'm sorry for the delay.  Thank you!

/mjt