consoles: Don't use listening address to connect to VNC

The listening address is most likely 127.0.0.1 (libvirt default) or
0.0.0.0 (yolo config). Neither of these works remotely.

Let's tell the remote viewer some address that has a chance of
working. More complicated setups, like a bastion host or connecting
via SSH inside Cockpit, might not work because of networking routing
challanges, but at least we get better error messages like "No route
to host" etc.

Also, with the libvirt default of only listening on 127.0.0.1, no
remote connection will work. But again, we now at least get the
expected "Connection refused" error message.

src/components/vm/consoles/consoles.jsx

@@ -143,7 +143,23 @@ class Consoles extends React.Component {
     onDesktopConsoleDownload (type) {
         const { vm } = this.props;
         // fire download of the .vv file
-        domainDesktopConsole({ name: vm.name, id: vm.id, connectionName: vm.connectionName, consoleDetail: vm.displays.find(display => display.type == type) });
+        const consoleDetail = vm.displays.find(display => display.type == type);
+
+        let address;
+        if (cockpit.transport.host == "localhost") {
+            const app = cockpit.transport.application();
+            if (app.startsWith("cockpit+="))
+                address = app.substr(9);
+            else
+                address = window.location.hostname;
+        } else {
+            address = cockpit.transport.host;
+            const pos = address.indexOf("@");
+            if (pos >= 0)
+                address = address.substr(pos+1);
+        }
+
+        domainDesktopConsole({ name: vm.name, consoleDetail: Object.assign({}, consoleDetail, { address }) });
     }
 
     render () {