qemu vnc auth 3/4: Add VNC auth support from upstream QEMU

This patch adds in the upstream QEMU VNC authentication code. This
spports the previous VNC password auth scheme, as well as the VeNCrypt
protocol extension. The latter allows for performing a TLS handshake,
and client verification of the server identify using x509
certificates. It is also possible for the server to request a client
certificate and validate that as a simple auth scheme. The code
depends on GNU TLS for SSL APIs, and the configure script will
auto-detect this.

The image.py code is changed to  deal with the new syntax for the -vnc
option.  In particular password authentication is now enabled by
giving the 'password' flag,

eg -vnc 0.0.0:1,password

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

tools/python/xen/xend/image.py

@@ -31,6 +31,7 @@ from xen.xend.XendOptions import instance as xenopts
 from xen.xend.xenstore.xstransact import xstransact
 from xen.xend.xenstore.xswatch import xswatch
 from xen.xend import arch
+from xen.xend import XendOptions
 
 xc = xen.lowlevel.xc.xc()
 
@@ -214,27 +215,27 @@ class ImageHandler:
                             'vncpasswd'):
                     if key in vmConfig['platform']:
                         vnc_config[key] = vmConfig['platform'][key]
+            if vnc_config.has_key("vncpasswd"):
+                passwd = vnc_config["vncpasswd"]
+            else:
+                passwd = XendOptions.instance().get_vncpasswd_default()
+            vncopts = ""
+            if passwd:
+                self.vm.storeVm("vncpasswd", passwd)
+                vncopts = vncopts + ",password"
+                log.debug("Stored a VNC password for vfb access")
+            else:
+                log.debug("No VNC passwd configured for vfb access")
 
             vnclisten = vnc_config.get('vnclisten',
-                                       xenopts().get_vnclisten_address())
+                                       XendOptions.instance().get_vnclisten_address())
             vncdisplay = vnc_config.get('vncdisplay', 0)
             ret.append('-vnc')
-            ret.append("%s:%s" % (vnclisten, vncdisplay))
-            
+            ret.append("%s:%s%s" % (vnclisten, vncdisplay, vncopts))
+
             if vnc_config.get('vncunused', 0):
                 ret.append('-vncunused')
 
-            # Store vncpassword in xenstore
-            vncpasswd = vnc_config.get('vncpasswd')
-            if not vncpasswd:
-                vncpasswd = xenopts().get_vncpasswd_default()
-
-            if vncpasswd is None:
-                raise VmError('vncpasswd is not setup in vmconfig or '
-                              'xend-config.sxp')
-
-            if vncpasswd != '':
-                self.vm.storeVm('vncpasswd', vncpasswd)
         elif has_sdl:
             # SDL is default in QEMU.
             pass