Fix bug in TLS authentication ("Daniel P. Berrange")

Fix bug in TLS authentication ("Daniel P. Berrange")

This patch was previously posted here:

  http://lists.gnu.org/archive/html/qemu-devel/2009-02/msg00820.html

In the case where the TLS handshake does *not* block on I/O, QEMU
sends the next 'start sub-auth' message twice. This seriously confuses
the VNC client :-) Fortunately the chances of the handshake not blocking
are close to zero for a TCP socket, which is why it has not been noticed
thus far. Even with both client & server on localhost, I can only hit the
bug 1 time in 20.

NB, the diff context here is not too informative. If you look at the
full code you'll see that a few lines early we called vnc_start_tls()
which called vnc_continue_handshake() which called the method
start_auth_vencrypt_subauth(). Hence, fixing the bug, just involves
removing the 2nd bogus call to start_auth_vencrypt_subauth() as per
this patch.

(cherry picked from commit adc5ec856c557f75adc60b310e5b1d38210a289c)

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Fedora-patch: 01-tls-handshake-fix.patch