I started looking into this after seeing

  FAIL: virnetsockettest
  ======================

  TEST: virnetsockettest
   1) Socket TCP/IPv4 Accept                       ... libvirt: XML-RPC error : Unable to resolve address '127.0.0.1' service '5672': Address family for hostname not supported
  FAILED
   2) Socket TCP/IPv6 Accept                       ... OK
   3) Socket TCP/IPv4+IPv6 Accept                  ... OK
   4) Socket TCP/IPv4+IPv6 Accept                  ... OK
   5) Socket UNIX Accept                           ... OK
   6) Socket UNIX Addrs                            ... OK
   7) Socket External Command /dev/zero            ... OK
   8) Socket External Command /dev/does-not-exist  ... libvirt: XML-RPC error : End of file while reading data: /bin/cat: /dev/does-not-exist: No such file or directory: Input/output error
  OK
   9) SSH test 1                                   ... OK
  10) SSH test 2                                   ... OK
  11) SSH test 3                                   ... OK
  12) SSH test 4                                   ... libvirt: XML-RPC error : End of file while reading data: Cannot connect to host nosuchhost: Input/output error
  OK
  13) SSH test 5                                   ... libvirt: XML-RPC error : End of file while reading data: : Input/output error
  OK
  14) SSH test 6                                   ... OK
  15) SSH test 7                                   ... OK

during a Debian package build.

Full log:

  https://buildd.debian.org/status/fetch.php?pkg=libvirt&arch=armel&ver=6.4.0-2&stamp=1594738948&raw=0

Just a few days ago, this issue was discussed in

  https://lists.debian.org/debian-devel/2020/07/msg00070.html

and libvirt was mentioned explicitly as a package that could be
affected by it.

Reproducing the issue is quite simple: just remove all IPv4
addresses *except* the one assigned to 'lo', and you'll see it
immediately. The problem seems to be that, in this configuration,
virNetSocketCheckProtocols() reports that both IPv4 and IPv6 are
available, but XML-RPC is apparently not happy with that.

I'm pretty bad at networking, so I'm reporting this in the hope that
someone else will figure it out O:-)

Anyway, there's another scenario that I found while digging: if you
remove *all* IPv4 addresses, *including* the one assigned to 'lo',
you get a different failure. My patch addresses this last one.

Andrea Bolognani (2):
  tests: Don't assume IPv4 connectivity is available
  tests: Minimize variable scope

 tests/virnetsockettest.c | 23 ++++++++++++++---------
 1 file changed, 14 insertions(+), 9 deletions(-)

-- 
2.25.4

On 7/14/20 10:32 PM, Andrea Bolognani wrote:
> I started looking into this after seeing
> 
>    FAIL: virnetsockettest
>    ======================
> 
>    TEST: virnetsockettest
>     1) Socket TCP/IPv4 Accept                       ... libvirt: XML-RPC error : Unable to resolve address '127.0.0.1' service '5672': Address family for hostname not supported
>    FAILED

> 
> during a Debian package build.
> 
> Full log:
> 
>    https://buildd.debian.org/status/fetch.php?pkg=libvirt&arch=armel&ver=6.4.0-2&stamp=1594738948&raw=0
> 
> Just a few days ago, this issue was discussed in
> 
>    https://lists.debian.org/debian-devel/2020/07/msg00070.html
> 
> and libvirt was mentioned explicitly as a package that could be
> affected by it.

Indeed. I'm able to reproduce and working on a fix as we speak.
The problem is that our test assumes that if there is an interface with 
IPv4 address (as returned by getifaddrs()) then getaddrinfo() of an IPv4 
address succeeds. We've seen with IPv6 that it is not true - that's why 
virNetSocketCheckProtocols() does explicit getaddrinfo() for an IPv6 
address. We need to do the same for IPv4.

Anyway, for these two:

Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Michal

On Wed, 2020-07-15 at 12:38 +0200, Michal Privoznik wrote:
> On 7/14/20 10:32 PM, Andrea Bolognani wrote:
> > I started looking into this after seeing
> > 
> >    FAIL: virnetsockettest
> >    ======================
> > 
> >    TEST: virnetsockettest
> >     1) Socket TCP/IPv4 Accept                       ... libvirt: XML-RPC error : Unable to resolve address '127.0.0.1' service '5672': Address family for hostname not supported
> >    FAILED
> > during a Debian package build.
> > 
> > Full log:
> > 
> >    https://buildd.debian.org/status/fetch.php?pkg=libvirt&arch=armel&ver=6.4.0-2&stamp=1594738948&raw=0
> > 
> > Just a few days ago, this issue was discussed in
> > 
> >    https://lists.debian.org/debian-devel/2020/07/msg00070.html
> > 
> > and libvirt was mentioned explicitly as a package that could be
> > affected by it.
> 
> Indeed. I'm able to reproduce and working on a fix as we speak.
> The problem is that our test assumes that if there is an interface with 
> IPv4 address (as returned by getifaddrs()) then getaddrinfo() of an IPv4 
> address succeeds. We've seen with IPv6 that it is not true - that's why 
> virNetSocketCheckProtocols() does explicit getaddrinfo() for an IPv6 
> address. We need to do the same for IPv4.

That's what I thought needed to happen, but I lack the networking
know-how to write the patches myself O:-)

> Anyway, for these two:
> 
> Reviewed-by: Michal Privoznik <mprivozn@redhat.com>

Thanks, pushed now.

-- 
Andrea Bolognani / Red Hat / Virtualization