python-3.x - argparse '参数 1 必须是 str、bytes 或 bytearray，而不是 None'

Question

import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import sys
from scapy.all import *
import argparse
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("--remote_host")
parser.add_argument("--verbose")
parser.add_argument("--help", action='store_true')
args = parser.parse_args()


if args.help:
    print("HELP...")

# Define end host and TCP port range
hostInput    = args.remote_host
host  = socket.gethostbyname(hostInput)
port_range = [21,22,23,25,53,80,110,135,137,138,139,443,1433,1434,8080]

# Send SYN with random Src Port for each Dst port
for dst_port in port_range:
    src_port = random.randint(1025,65534)
    resp = sr1(
        IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags="S"),timeout=1,
        verbose=int(args.verbose),
    )

    if resp is None:
        print(f"{host}:{dst_port} is filtered (silently dropped).")

    elif(resp.haslayer(TCP)):
        if(resp.getlayer(TCP).flags == 0x12):
            # Send a gratuitous RST to close the connection
            send_rst = sr(
                IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags='R'),
                timeout=1,
                verbose=int(args.verbose),
            )
            print(f"{host}:{dst_port} is open.")

        elif (resp.getlayer(TCP).flags == 0x14):
            print(f"{host}:{dst_port} is closed.")

    elif(resp.haslayer(ICMP)):
        if(
            int(resp.getlayer(ICMP).type) == 3 and
            int(resp.getlayer(ICMP).code) in [1,2,3,9,10,13]
        ):
            print(f"{host}:{dst_port} is filtered (silently dropped).")

运行--remote_host 127.0.0.1 --verbose 1正常，没有错误

运行--help产生：

TypeError: gethostbyname() argument 1 must be str, bytes or bytearray, not None

注意：当然只有当我包含以下所有行时才会出现上述错误print("Help...")

这是完整的回溯：

Python 3.8.0 (tags/v3.8.0:fa919fd, Oct 14 2019, 19:37:50) [MSC v.1916 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license()" for more information.
>>> 
= RESTART: C:\Users\00082563\AppData\Local\Programs\Python\AT2_PythonNetworkApplications.v1.1a\Scenario 1\logger.py
HELP...
Traceback (most recent call last):
  File "C:\Users\00082563\AppData\Local\Programs\Python\AT2_PythonNetworkApplications.v1.1a\Scenario 1\logger.py", line 48, in <module>
    host  = socket.gethostbyname(hostInput)
TypeError: gethostbyname() argument 1 must be str, bytes or bytearray, not None
>>>

标签： python-3.xargparse

Answer 1

正如上述评论中所建议的，我需要在以下情况下退出程序：

if args.help:
    print("HELP...")

因此，在下面的脚本中，用户可以在 CLI 中添加--remote_host google.com --verbose 0（或详细 1 以获得完整的详细信息...）

用户可以改为在 CLI--help中使用打印自定义帮助部分，之后程序将退出。

#!/usr/bin/env python


import logging
logging.getLogger("scapy.runtime").setLevel(logging.ERROR)
import sys
from scapy.all import *
import argparse
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("--remote_host")
parser.add_argument("--verbose")
parser.add_argument("--help", action='store_true')
args = parser.parse_args()


if args.help:
    print("Help section...")
    exit()
 
# Define end host and TCP port range
hostInput    = args.remote_host
host  = socket.gethostbyname(hostInput)
port_range = [21,22,23,25,53,80,110,135,137,138,139,443,1433,1434,8080]

# Send SYN with random Src Port for each Dst port
for dst_port in port_range:
    src_port = random.randint(1025,65534)
    resp = sr1(
        IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags="S"),timeout=1,
        verbose=int(args.verbose),
    )

    if resp is None:
        print(f"{host}:{dst_port} is filtered (silently dropped).")

    elif(resp.haslayer(TCP)):
        if(resp.getlayer(TCP).flags == 0x12):
            # Send a gratuitous RST to close the connection
            send_rst = sr(
                IP(dst=host)/TCP(sport=src_port,dport=dst_port,flags='R'),
                timeout=1,
                verbose=int(args.verbose),
            )
            print(f"{host}:{dst_port} is open.")

        elif (resp.getlayer(TCP).flags == 0x14):
            print(f"{host}:{dst_port} is closed.")

    elif(resp.haslayer(ICMP)):
        if(
            int(resp.getlayer(ICMP).type) == 3 and
            int(resp.getlayer(ICMP).code) in [1,2,3,9,10,13]
        ):
            print(f"{host}:{dst_port} is filtered (silently dropped).")