virsh: fix IP address in domdisplay for listen type='network'

https://bugzilla.redhat.com/show_bug.cgi?id=1191016

virsh's domdisplay command looks in /domain/devices/graphics/@listen
of the domain's XML for the listen address, however for listen
type='network' (added in libvirt 0.9.4), the <graphics> element
doesn't have a listen attribute, but has a <listen> subelement,
*still* with no address (this is the inactive XML):

 <graphics type='spice' autoport='yes' keymap='en-us'>
  <listen type='network' network='default'/>
 </graphics>

However, at domain start time the <listen> subelement gets its address
attribute filled in once libvirt figures out the IP address associated
with the named network (this is the status XML):

 <graphics type='spice' port='5901' autoport='yes' keymap='en-us'>
  <listen type='network' address='192.168.122.1' network='default'/>
 </graphics>

So in these cases, we need to look at
/domain/devices/graphics/listen/@address instead.

Even though another patch is being pushed that will backfill
listen/@address into @listen, this patch is still useful, as it fixes
domdisplay for cases of a new virsh (with this patch) connecting to a
libvirtd that is newer than 0.9.4 but doesn't have the followup patch.
Signed-off-by: NLuyao Huang <lhuang@redhat.com>
Signed-off-by: NLaine Stump <laine@laine.org>

tools/virsh-domain.c

 /*
  * virsh-domain.c: Commands to manage domain
  *
- * Copyright (C) 2005, 2007-2014 Red Hat, Inc.
+ * Copyright (C) 2005, 2007-2015 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -10024,7 +10024,7 @@ cmdDomDisplay(vshControl *ctl, const vshCmd *cmd)
     int tmp;
     int flags = 0;
     bool params = false;
-    const char *xpath_fmt = "string(/domain/devices/graphics[@type='%s']/@%s)";
+    const char *xpath_fmt = "string(/domain/devices/graphics[@type='%s']/%s)";
     virSocketAddr addr;
 
     if (!(dom = vshCommandOptDomain(ctl, cmd, NULL)))
@@ -10054,7 +10054,7 @@ cmdDomDisplay(vshControl *ctl, const vshCmd *cmd)
             continue;
 
         /* Create our XPATH lookup for the current display's port */
-        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "port") < 0)
+        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "@port") < 0)
             goto cleanup;
 
         /* Attempt to get the port number for the current graphics scheme */
@@ -10068,7 +10068,7 @@ cmdDomDisplay(vshControl *ctl, const vshCmd *cmd)
 
         /* Create our XPATH lookup for TLS Port (automatically skipped
          * for unsupported schemes */
-        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "tlsPort") < 0)
+        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "@tlsPort") < 0)
             goto cleanup;
 
         /* Attempt to get the TLS port number */
@@ -10081,7 +10081,7 @@ cmdDomDisplay(vshControl *ctl, const vshCmd *cmd)
             continue;
 
         /* Create our XPATH lookup for the current display's address */
-        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "listen") < 0)
+        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "@listen") < 0)
             goto cleanup;
 
         /* Attempt to get the listening addr if set for the current
@@ -10089,13 +10089,29 @@ cmdDomDisplay(vshControl *ctl, const vshCmd *cmd)
         listen_addr = virXPathString(xpath, ctxt);
         VIR_FREE(xpath);
 
+        if (!listen_addr) {
+            /* The subelement address - <listen address='xyz'/> -
+             * *should* have been automatically backfilled into its
+             * parent <graphics listen='xyz'> (which we just tried to
+             * retrieve into listen_addr above) but in some cases it
+             * isn't, so we also do an explicit check for the
+             * subelement (which, by the way, doesn't exist on libvirt
+             * < 0.9.4, so we really do need to check both places)
+             */
+            if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "listen/@address") < 0)
+                goto cleanup;
+
+            listen_addr = virXPathString(xpath, ctxt);
+            VIR_FREE(xpath);
+        }
+
         /* We can query this info for all the graphics types since we'll
          * get nothing for the unsupported ones (just rdp for now).
          * Also the parameter '--include-password' was already taken
          * care of when getting the XML */
 
         /* Create our XPATH lookup for the password */
-        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "passwd") < 0)
+        if (virAsprintf(&xpath, xpath_fmt, scheme[iter], "@passwd") < 0)
             goto cleanup;
 
         /* Attempt to get the password */