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Re: [libvirt] Some questions about virConnectAuthCallbackPtr



On Mon, Oct 15, 2012 at 12:17:42PM +0200, Peter Krempa wrote:
> On 10/13/12 19:08, Richard W.M. Jones wrote:
> >On Sat, Oct 13, 2012 at 05:47:24PM +0100, Richard W.M. Jones wrote:
> >>BTW I cannot get the libssh2 backend in libvirt to work.  For
> >>every host it says:
> >>
> >>   libvirt_auth.c: authentication required for libvirt URI 'qemu+libssh2://localhost/system'
> >>   libvirt_auth.c: credential 'echoprompt'
> >>   Accept SSH host key with hash '<correct host key>' for host 'localhost:22' (y/n)?: y
> >>   libguestfs: error: could not connect to libvirt (code 85, domain 50): SSH transport error: SSH host key for 'localhost' (<correct host key>) was not accepted
> >>
> >>No idea what I'm doing wrong.  Nothing in the logs on the server
> >>indicate that anything is wrong on the remote side.
> >
> >Peter,
> >
> >This is because of a bug in the libvirt code:
> >
> >        if (!askKey.result ||
> >            STRCASENEQ(askKey.result, "y")) {
> >            virReportError(VIR_ERR_SSH,
> >                           _("SSH host key for '%s' (%s) was not accepted"),
> >                           sess->hostname, keyhash);
> >            VIR_FREE(keyhash);
> >            VIR_FREE(askKey.result);
> >            return -1;
> >        }
> >
> >The problem with this code is that it ignores the resultlen field.
> >
> >If the caller passes result[] = { 'y' } (no trailing \0), resultlen = 1,
> >(which IMHO is a correct use of the API as described by the
> >documentation), then STRCASENEQ above will not match the string.
> >
> >You need to use something like:
> >
> >   askKey.resultlen >= 1 && askKey.result[0] == 'y'
> >
> >or else some sort of memcmp function.
> >
> >Rich.
> >
> 
> 
> Hm, that seems to be a fair point. I'll have a look and try to fix
> this today.

And FWIW this case would fail (badly) too:

  result[] = { 'y', ... }; // ie. some random data
  resultlen = 0

Rich.

-- 
Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones
virt-p2v converts physical machines to virtual machines.  Boot with a
live CD or over the network (PXE) and turn machines into Xen guests.
http://et.redhat.com/~rjones/virt-p2v


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