feedback when non existing group selected

client.py

@@ -14,10 +14,15 @@ class Client(multiprocessing.Process):
 
     def run(self):
         print("Client: Up and running")
+        
+        while True:
             action = input("Client: Enter type of action ('r' to register): ")
             if (action == "r"):
                 group = input("Client: Which group dou you want to join? ")
-            self.register("register", group)
+                success = self.register("register", group)
+
+                if success == 0:
+                    continue
 
                 send_thread = threading.Thread(target=self.send_message)
                 receive_thread = threading.Thread(target=self.receive_messages)
@@ -31,9 +36,6 @@ class Client(multiprocessing.Process):
                 send_thread.join()
                 receive_thread.join()
                 
-        else: 
-            message = input("Client: Enter message:")
-            print(message)
 
     def register(self, message_type, message_group):
         PORT = 49153
@@ -49,6 +51,9 @@ class Client(multiprocessing.Process):
         
         print('Client: Received message from server: ', data.decode('utf-8'))
 
+        if data.decode('utf-8') == "Group does not exist":
+            success = 0
+        else: 
             # search for server ip_address in message from server
             ip_pattern = r'\b(?:\d{1,3}\.){3}\d{1,3}\b'
             matches = re.findall(ip_pattern, data.decode('utf-8'))
@@ -59,8 +64,12 @@ class Client(multiprocessing.Process):
             #self.registered_server = server
             print("Client: My server: ", self.registered_server_address)
 
+            success = 1
+
         broadcast_socket.close()
 
+        return success
+
     def send_message(self):
         PORT = 50001
 

server.py

@@ -456,6 +456,7 @@ class Server(multiprocessing.Process):
        
         if group not in self.local_group_cache:
             print(self.server_id+": "+"Group "+group+" doesn't exist.")
+            self.send_negative_reply_to_client(client_addr)
     
         else:
             print(self.server_id+": "+"Group "+group+" exists")
@@ -482,6 +483,14 @@ class Server(multiprocessing.Process):
 
         return addr
     
+    def send_negative_reply_to_client(self, client_addr):
+        PORT = 1001
+        message = "Group does not exist"
+        server_socket = socket.socket(socket.AF_INET, socket.SOCK_DGRAM)
+        server_socket.connect((self.server_address, PORT))
+        server_socket.sendto(str.encode(message), client_addr)
+        server_socket.close()
+    
     def send_reply_to_client(self, server_addr, client_addr):
         PORT = 1000
         message = 'Hi ' + client_addr[0] + ' this is your groupchat server: ' + server_addr