add sending udp message on behalf of an non-supporting server

secop.py

@@ -110,9 +110,12 @@ class UdpStream(Base):
             except socket.error:  # pragma: no cover
                 return None
             msg = json.loads(msg.decode('utf-8'))
-            if msg['SECoP'] != 'node':
+            if msg['SECoP'] == 'for_other_node':
+                uri = msg['uri']
+            elif msg['SECoP'] == 'node':
+                uri = f"{addr[0]}:{msg['port']}"
+            else:
                 continue
-            uri = f"{addr[0]}:{msg['port']}"
             yield SecopStream, uri, msg['equipment_id']
 
 
@@ -144,5 +147,14 @@ class ScanStream(UdpStream):
         self.select_dict[sock.fileno()] = self
 
 
+def send_fake_udp(uri, equipment_id='fake'):
+    sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+    sock.setsockopt(socket.SOL_SOCKET, socket.SO_BROADCAST, 1)
+    msg = json.dumps({
+        'SECoP': 'for_other_node',
+        'uri': uri,
+        'equipment_id': equipment_id,
+    }, ensure_ascii=False, separators=(',', ':')).encode('utf-8')
+    sock.sendto(msg, ('255.255.255.255', SECOP_UDP_PORT))