feat(udp): server and client skeleton refactored

- check for UDP connection via ping/pong

src/myftp/client.py

@@ -0,0 +1,139 @@
+from socket import socket, AF_INET, SOCK_DGRAM
+from typing import Tuple
+from argparse import ArgumentParser
+
+# custome type to represent the hostname(server name) and the server port
+Address = Tuple[str, int]
+
+
+class UDPClient:
+    def __init__(self, server_name: str, server_port: int, debug: bool):
+        self.server_name: str = server_name
+        self.server_port: int = server_port
+        self.mode: str = "UDP"
+        self.pong_received: bool = False
+        self.debug = debug
+
+    def run(self):
+        # server cannot be reached, stop the client immediately
+        if not self.pong_received:
+            return
+
+        client_socket = socket(AF_INET, SOCK_DGRAM)
+
+        client_socket.connect((self.server_name, self.server_port))
+
+        message = input("input lowercase sentence: ")
+
+        client_socket.send(message.encode())
+
+        try:
+            modified_message = client_socket.recv(2048)
+            print(modified_message.decode())
+
+        except ConnectionRefusedError:
+            print(
+                f"myftp> - {self.mode} - ConnectionRefusedError happened. Please restart the client program, make sure the server is running and/or put a different server name and server port."
+            )
+        finally:
+            client_socket.close()
+
+    # ping pong UDP
+    def check_udp_server(self):
+        # Create a UDP socket
+        client_socket = socket(AF_INET, SOCK_DGRAM)
+        # will time out after 5 seconds
+        client_socket.settimeout(5)
+
+        try:
+            # Send a test message to the server
+            message = b"ping"
+            client_socket.sendto(message, (self.server_name, self.server_port))
+
+            # Receive the response
+            data, _ = client_socket.recvfrom(1024)
+
+            # If the server responds, consider the address valid
+            print(
+                f"myftp> - {self.mode} - Server at {self.server_name} is valid. Response received: {data.decode('utf-8')}"
+            )
+
+            # code reached here meaning no problem with the connection
+            self.pong_received = True
+
+        except TimeoutError:
+            # Server did not respond within the specified timeout
+            print(
+                f"myftp> - {self.mode} - Server at {self.server_name} did not respond within 5 seconds. Check the address or server status."
+            )
+
+        finally:
+            # Close the socket
+            client_socket.close()
+
+
+def get_address_input() -> Address:
+    while True:
+        try:
+            # Get input as a space-separated string
+            input_string = input("myftp>Provide IP address and Port number\n")
+
+            # Split the input into parts
+            input_parts = input_string.split()
+
+            # Ensure there are exactly two parts
+            if len(input_parts) != 2:
+                raise ValueError(
+                    "myftp>Invalid input. Please enter a servername/hostname/ip address as a string and the port number as an integer separated by a space."
+                )
+
+            # Extract the values and create the tuple
+            string_part, int_part = input_parts
+            address = (string_part, int(int_part))
+
+            # Valid tuple, return it
+            return address
+
+        except ValueError as e:
+            print(
+                f"Error: {e}. Invalid input. Please enter a servername/hostname/ip address as a string and the port number as an integer separated by a space."
+            )
+
+
+def init():
+    arg_parser = ArgumentParser(description="A FTP client written in Python")
+
+    arg_parser.add_argument(
+        "--debug",
+        type=int,
+        choices=[0, 1],
+        default=0,
+        required=False,
+        help="Enable or disable the flag (0 or 1)",
+    )
+
+    args = arg_parser.parse_args()
+
+    while (
+        protocol_selection := input("myftp>Press 1 for TCP, Press 2 for UDP\n")
+    ) not in {"1", "2"}:
+        print("myftp>Invalid choice. Press 1 for TCP, Press 2 for UDP")
+
+    # UDP client selected here
+    if protocol_selection == "2":
+        user_supplied_address = get_address_input()
+
+        udp_client = UDPClient(
+            user_supplied_address[0], user_supplied_address[1], args.debug
+        )
+
+        udp_client.check_udp_server()
+
+        udp_client.run()
+    else:
+        # tcp client here
+        pass
+
+
+if __name__ == "__main__":
+    init()

src/myftp/server.py

@@ -27,8 +27,12 @@ class UDPServer:
                     f"received message from client at {clientAddress}: {message_in_utf8}"
                 ) if self.debug else None
 
-                modified_message = message_in_utf8.upper()
+                if message_in_utf8 == "ping":
-                self.server_socket.sendto(modified_message.encode(), clientAddress)
+                    response_message = "pong"
+                else:
+                    response_message = message_in_utf8.upper()
+
+                self.server_socket.sendto(response_message.encode(), clientAddress)
 
         except KeyboardInterrupt:
             shut_down = True
@@ -40,7 +44,7 @@ class UDPServer:
 
 
 def init():
-    parser = ArgumentParser(description="A FTP server written in Python. UDP version")
+    parser = ArgumentParser(description="A FTP server written in Python")
 
     parser.add_argument(
         "port_number", type=int, help="Port number for the server. Default = 12000"
@@ -56,10 +60,21 @@ def init():
 
     args = parser.parse_args()
 
+    while (
+        protocol_selection := input("myftp>Press 1 for TCP, Press 2 for UDP\n")
+    ) not in {"1", "2"}:
+        print("myftp>Invalid choice. Press 1 for TCP, Press 2 for UDP")
+
+    # UDP client selected here
+    if protocol_selection == "2":
         udp_server = UDPServer("127.0.0.1", args.port_number, args.debug)
 
         udp_server.run()
 
+    else:
+        # tcp client here
+        pass
+
 
 if __name__ == "__main__":
     init()

src/myftp/udp/udp_client.py

@@ -1,64 +0,0 @@
-from socket import socket, AF_INET, SOCK_DGRAM
-from argparse import ArgumentParser
-
-
-class UDPClient:
-    def __init__(self, server_name: str, server_port: int, debug: bool):
-        self.server_name = server_name
-        self.server_port = server_port
-        self.debug = debug
-
-        print(f"New UDP connection created to server at {server_name}:{server_port}")
-
-    def run(self):
-        client_socket = socket(AF_INET, SOCK_DGRAM)
-
-        try:
-            client_socket.connect((self.server_name, self.server_port))
-        except Exception:
-            print(
-                f"Error with the server IP address {self.server_name} or with the server port number {self.server_port}"
-            )
-
-        message = input("input lowercase sentence: ")
-
-        client_socket.send(message.encode())
-
-        modified_message = client_socket.recv(2048)
-
-        print(modified_message.decode())
-
-        client_socket.close()
-
-
-def init():
-    parser = ArgumentParser(description="A FTP server written in Python. UDP version")
-
-    parser.add_argument(
-        "server_name",
-        type=str,
-        default="127.0.0.1",
-        help="IP address or hostname for the server. Default = localhost",
-    )
-
-    parser.add_argument(
-        "port_number", type=int, help="Port number for the server. Default = 12000"
-    )
-
-    parser.add_argument(
-        "--debug",
-        type=int,
-        choices=[0, 1],
-        default=0,
-        help="Enable or disable the flag (0 or 1)",
-    )
-
-    args = parser.parse_args()
-
-    udp_server = UDPClient(args.server_name, args.port_number, args.debug)
-
-    udp_server.run()
-
-
-if __name__ == "__main__":
-    init()