375 lines
12 KiB
Python
375 lines
12 KiB
Python
# Author: Minh Tran and Angelo Reoligio
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# Date: November 30, 2023
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# Description: FTP server (both UDP and TCP implemented)
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from socket import socket, AF_INET, SOCK_DGRAM
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from argparse import ArgumentParser
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from typing import Optional, Tuple
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import traceback
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import os
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# Res-codes
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rescode_success_dict: dict[str, int] = {
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"correct_put_and_change_request_rescode": 0b000,
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"correct_get_request_rescode": 0b001,
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"correct_summary_request_rescode": 0b010,
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"help_rescode": 0b110,
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}
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rescode_fail_dict: dict[str, int] = {
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"file_not_error_rescode": 0b011,
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"unknown_request_rescode": 0b100,
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"unsuccessful_change_rescode": 0b101,
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}
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# opcodes
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op_codes_dict: dict[int, str] = {
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0b000: "put",
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0b001: "get",
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0b010: "change",
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0b011: "summary",
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0b100: "help",
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0b101: "unknown",
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}
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class Server:
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def __init__(
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self,
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server_name: str,
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server_port: int,
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directory_path: str,
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debug: bool,
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protocol: str,
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) -> None:
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self.server_name = server_name
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self.server_port = server_port
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self.protocol: str = protocol
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self.directory_path = directory_path
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self.debug = debug
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def run(self):
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self.server_socket = socket(AF_INET, SOCK_DGRAM)
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self.server_socket.bind((self.server_name, self.server_port))
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print(
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f"myftp> - {self.protocol} - Server is ready to receive at {self.server_name}:{self.server_port}"
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) if self.debug else None
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shut_down = False
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try:
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while not shut_down:
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print(
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f"myftp> - {self.protocol} ------------------------------------------------------------------"
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) if self.debug else None
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req_payload, clientAddress = self.server_socket.recvfrom(2048)
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first_byte = bytes([req_payload[0]])
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request_type, filename_length_in_bytes = self.decode_first_byte(
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first_byte
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)
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print(
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f"myftp> - {self.protocol} - Received message from client at {clientAddress}: {req_payload}"
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) if self.debug else None
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# help request handling
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if request_type == "help":
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print(
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f"myftp> - {self.protocol} - Client message parsed. Received help request"
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) if self.debug else None
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rescode = rescode_success_dict["help_rescode"]
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response_data = "get,put,summary,change,help,bye".encode("ascii")
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filename = None
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filename_length_in_bytes = None
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elif request_type == "get":
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pre_payload = self.process_get_req(req_payload[1:])
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if (
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pre_payload[0] is not None
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and pre_payload[1] is not None
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and pre_payload[2] is not None
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):
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rescode = rescode_success_dict["correct_get_request_rescode"]
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filename = pre_payload[0]
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filename_length_in_bytes = pre_payload[2]
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response_data = pre_payload[1]
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else:
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rescode = rescode_fail_dict["file_not_error_rescode"]
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filename_length_in_bytes = None
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filename = None
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response_data = None
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elif request_type == "put":
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# put request failed since there wasnt a file sent from client
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if filename_length_in_bytes == 0:
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rescode = rescode_fail_dict["unsuccessful_change_rescode"]
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filename_length_in_bytes = None
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filename = None
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response_data = None
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# put request success
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else:
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rescode = self.process_put_req(
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filename_length_in_bytes, req_payload[1:]
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)
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filename_length_in_bytes = None
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filename = None
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response_data = None
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elif request_type == "unknown":
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rescode = rescode_fail_dict["unknown_request_rescode"]
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filename_length_in_bytes = None
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filename = None
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response_data = None
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res_payload: bytes = self.build_res_payload(
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rescode=rescode, # type: ignore
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filename_length=filename_length_in_bytes,
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filename=filename, # type: ignore
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response_data=response_data, # type:ignore
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)
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self.server_socket.sendto(res_payload, clientAddress)
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print(
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f"myftp> - {self.protocol} - Sent message to client at {clientAddress}: {res_payload}"
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) if self.debug else None
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except KeyboardInterrupt:
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shut_down = True
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self.server_socket.close()
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print(f"myftp> - {self.protocol} - Server shutting down")
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finally:
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print(f"myftp> - {self.protocol} - Closed the server socket")
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def decode_first_byte(self, first_byte: bytes) -> Tuple[str, int]:
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"""
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Retrieve the request_type from first byte
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"""
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if len(first_byte) != 1:
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raise ValueError("Input is not 1 byte")
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first_byte_to_binary = int.from_bytes(first_byte, "big")
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try:
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request_type = op_codes_dict[first_byte_to_binary >> 5]
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filename_length_in_bytes = first_byte_to_binary & 0b00011111
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print(
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f"myftp> - {self.protocol} - First byte parsed. Request type: {request_type}. Filename length in bytes: {filename_length_in_bytes}"
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)
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except KeyError:
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raise KeyError("Cant not find the request type")
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return request_type, filename_length_in_bytes
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def process_put_req(self, filename_length: int, req_payload: bytes) -> int:
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"""
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Reconstruct file put by client
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"""
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filename = req_payload[:filename_length].decode("ascii")
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filesize = int.from_bytes(
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req_payload[filename_length : filename_length + 4], "big"
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)
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file_content = req_payload[filename_length + 4 :]
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print(
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f"myftp> - {self.protocol} - Reconstructing the file {filename} of size {filesize} bytes on the server after the client finished sending"
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)
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try:
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with open(os.path.join(self.directory_path, filename), "wb") as file:
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file.write(file_content)
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print(
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f"myftp> - {self.protocol} - File {filename} uploaded successfully"
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)
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return rescode_success_dict["correct_put_and_change_request_rescode"]
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except Exception as error:
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traceback_info = traceback.format_exc()
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print(f"myftp> - {self.protocol} - {error} happened.")
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print(traceback_info)
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return rescode_fail_dict["unsuccessful_change_rescode"]
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def process_get_req(
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self, second_byte_to_byte_n: bytes
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) -> Tuple[Optional[str], Optional[bytes], Optional[int]]:
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"""
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Process the get request
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If successful, return the filename, content and the content_length
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If not, return None, None, None tuple
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"""
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filename = second_byte_to_byte_n.decode("ascii")
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try:
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with open(os.path.join(self.directory_path, filename), "rb") as file:
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content = file.read()
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content_length = len(content)
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return filename, content, content_length
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except FileNotFoundError:
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print(f"myftp> - {self.protocol} - file {filename} not found")
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return (None, None, None)
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# assembling the payload to send back to the client
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def build_res_payload(
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self,
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rescode: int,
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filename_length: Optional[int] = None,
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filename: Optional[str] = None,
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response_data: Optional[bytes] = None,
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) -> bytes:
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print(
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f"myftp> - {self.protocol} - Assembling response payload to be sent back to the client"
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)
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data_len = len(response_data) if response_data is not None else None
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print(
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f"myftp> - {self.protocol} - Rescode {format(rescode, '03b')}"
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) if self.debug else None
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print(
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f"myftp> - {self.protocol} - Length of data {data_len}"
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) if self.debug else None
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print(
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f"myftp> - {self.protocol} - Data {response_data}"
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) if self.debug else None
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# convert to binary
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try:
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# get case
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if filename is not None:
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first_byte = ((rescode << 5) + len(filename)).to_bytes(1, "big")
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# help case
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elif filename is None and response_data is not None:
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first_byte = ((rescode << 5) + len(response_data)).to_bytes(1, "big")
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# unsuccessful cases
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else:
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first_byte = (rescode << 5).to_bytes(1, "big")
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# we only need the firstbyte
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if filename is None:
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second_byte_to_FL_plus_five = None
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else:
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# get case
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second_byte_to_FL_plus_five = (
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filename.encode() + len(response_data).to_bytes(4, "big")
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if response_data is not None
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else None
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)
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print(
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f"myftp> - {self.protocol} - First byte assembled for rescode {format(rescode, '03b')}: {bin(int.from_bytes(first_byte, byteorder='big'))[2:]}"
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) if self.debug else None
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if second_byte_to_FL_plus_five is not None and response_data is not None:
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res_payload = first_byte + second_byte_to_FL_plus_five + response_data
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# help case
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elif second_byte_to_FL_plus_five is None and response_data is not None:
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res_payload = first_byte + response_data
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else:
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res_payload = first_byte
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return res_payload
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except Exception:
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raise
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def check_directory(path: str) -> bool:
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if os.path.exists(path):
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if os.path.isdir(path):
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if os.access(path, os.R_OK) and os.access(path, os.W_OK):
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return True
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else:
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print(f"Error: The directory '{path}' is not readable or writable.")
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else:
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print(f"Error: '{path}' is not a directory.")
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else:
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print(f"Error: The directory '{path}' does not exist.")
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return False
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def init():
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parser = ArgumentParser(description="A FTP server written in Python")
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parser.add_argument(
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"--port_number",
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default=12000,
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required=False,
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type=int,
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help="Port number for the server. Default = 12000",
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)
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parser.add_argument(
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"--directory", required=True, type=str, help="Path to the server directory"
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)
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parser.add_argument(
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"--ip_addr",
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default="0.0.0.0",
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required=False,
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type=str,
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help="Port number for the server. Default = 12000",
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)
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parser.add_argument(
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"--debug",
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type=int,
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choices=[0, 1],
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default=0,
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help="Enable or disable the flag (0 or 1)",
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)
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args = parser.parse_args()
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while (
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protocol_selection := input("myftp>Press 1 for TCP, Press 2 for UDP\n")
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) not in {"1", "2"}:
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print("myftp>Invalid choice. Press 1 for TCP, Press 2 for UDP")
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if not check_directory(args.directory):
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print(
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f"The directory '{args.directory}' does not exists or is not readable/writable."
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)
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return
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# UDP client selected here
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if protocol_selection == "2":
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udp_server = Server(
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args.ip_addr, args.port_number, args.directory, args.debug, "UDP"
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)
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udp_server.run()
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else:
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tcp_server = Server(
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args.ip_addr, args.port_number, args.directory, args.debug, "TCP"
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)
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tcp_server.run()
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if __name__ == "__main__":
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init()
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