avocado/vnc: add test_change_listen

Add simple test-case for new display-update qmp command.

Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@openvz.org>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20220401143936.356460-4-vsementsov@openvz.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

tests/avocado/vnc.py

@@ -8,9 +8,48 @@
 # This work is licensed under the terms of the GNU GPL, version 2 or
 # later.  See the COPYING file in the top-level directory.
 
+import socket
+from typing import List
+
 from avocado_qemu import QemuSystemTest
 
 
+VNC_ADDR = '127.0.0.1'
+VNC_PORT_START = 32768
+VNC_PORT_END = VNC_PORT_START + 1024
+
+
+def check_bind(port: int) -> bool:
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+        try:
+            sock.bind((VNC_ADDR, port))
+        except OSError:
+            return False
+
+    return True
+
+
+def check_connect(port: int) -> bool:
+    with socket.socket(socket.AF_INET, socket.SOCK_STREAM) as sock:
+        try:
+            sock.connect((VNC_ADDR, port))
+        except ConnectionRefusedError:
+            return False
+
+    return True
+
+
+def find_free_ports(count: int) -> List[int]:
+    result = []
+    for port in range(VNC_PORT_START, VNC_PORT_END):
+        if check_bind(port):
+            result.append(port)
+            if len(result) >= count:
+                break
+    assert len(result) == count
+    return result
+
+
 class Vnc(QemuSystemTest):
     """
     :avocado: tags=vnc,quick
@@ -51,3 +90,27 @@ def test_change_password(self):
         set_password_response = self.vm.qmp('change-vnc-password',
                                             password='new_password')
         self.assertEqual(set_password_response['return'], {})
+
+    def test_change_listen(self):
+        a, b, c = find_free_ports(3)
+        self.assertFalse(check_connect(a))
+        self.assertFalse(check_connect(b))
+        self.assertFalse(check_connect(c))
+
+        self.vm.add_args('-nodefaults', '-S', '-vnc', f'{VNC_ADDR}:{a - 5900}')
+        self.vm.launch()
+        self.assertEqual(self.vm.qmp('query-vnc')['return']['service'], str(a))
+        self.assertTrue(check_connect(a))
+        self.assertFalse(check_connect(b))
+        self.assertFalse(check_connect(c))
+
+        res = self.vm.qmp('display-update', type='vnc',
+                          addresses=[{'type': 'inet', 'host': VNC_ADDR,
+                                      'port': str(b)},
+                                     {'type': 'inet', 'host': VNC_ADDR,
+                                      'port': str(c)}])
+        self.assertEqual(res['return'], {})
+        self.assertEqual(self.vm.qmp('query-vnc')['return']['service'], str(b))
+        self.assertFalse(check_connect(a))
+        self.assertTrue(check_connect(b))
+        self.assertTrue(check_connect(c))