domain: Fix migratable XML with graphics/@listen

As of commit 69929941, we set graphics/@listen attribute according to the
first listen child element even if that element is of type='network'.
This was done for backward compatibility with applications which only
support the original listen attribute. However, by doing so we broke
migration to older libvirt which tried to check that the listen
attribute matches one of the listen child elements but which did not
take type='network' elements into account.

We are not concerned about compatibility with old applications when
formatting domain XML for migration for two reasons. The XML is consumed
only by libvirtd and the IP address associated with type='network'
listen address on the source host is just useless on the destination
host. Thus, we can safely avoid propagating the type='network' IP
address to graphics/@listen attribute when creating migratable XML.

https://bugzilla.redhat.com/show_bug.cgi?id=1265111Signed-off-by: NJiri Denemark <jdenemar@redhat.com>
(cherry picked from commit c0806dc3)

src/conf/domain_conf.c

@@ -19112,19 +19112,17 @@ virDomainGraphicsDefFormat(virBufferPtr buf,
     * <graphics>. This is done to improve backward compatibility.
     */
     for (i = 0; i < def->nListens; i++) {
-        virDomainGraphicsListenType listenType;
-
         if (flags & VIR_DOMAIN_DEF_FORMAT_MIGRATABLE &&
             def->listens[i].fromConfig)
             continue;
-        listenType = virDomainGraphicsListenGetType(def, i);
 
-        if (listenType == VIR_DOMAIN_GRAPHICS_LISTEN_TYPE_ADDRESS ||
-            (listenType == VIR_DOMAIN_GRAPHICS_LISTEN_TYPE_NETWORK &&
-             !(flags & VIR_DOMAIN_DEF_FORMAT_INACTIVE))) {
-            if ((listenAddr = virDomainGraphicsListenGetAddress(def, i)))
-                break;
-        }
+        if (def->listens[i].type == VIR_DOMAIN_GRAPHICS_LISTEN_TYPE_NETWORK &&
+            flags & (VIR_DOMAIN_DEF_FORMAT_INACTIVE |
+                     VIR_DOMAIN_DEF_FORMAT_MIGRATABLE))
+            continue;
+
+        if ((listenAddr = virDomainGraphicsListenGetAddress(def, i)))
+            break;
     }
 
     virBufferAsprintf(buf, "<graphics type='%s'", type);