Python socket.connect()报OSError[Errno22]无效参数问题排查

我写了一段Python代码，想遍历ARP列表里的设备IP，尝试用socket连接指定端口，代码如下：

import socket
import os


my_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

devices = []
print("Looking for open server. . .")
for device in os.popen('arp -a'):
    devices.append(device.split()[1].strip("()"))  # .strip("()")
# print(devices)

make_server = True
host = "192.168.4.24"  # "127.0.1.1"
port = 8000
for device in devices:
    try:
        my_socket.connect((device, port))
        make_server = False
        print(f"Connected to {device}")
        break
    except socket.error as error:
        pass
        # print(error)

if make_server:
    my_socket.connect((socket.gethostbyname(socket.gethostname()), port))
    print(f"Connected to {socket.gethostbyname(socket.gethostname())}")

执行后抛出错误：

Traceback (most recent call last):
  File "/Users/user/PycharmProjects/LAN_chat_app/Testing 1.py", line 41, in <module>
    my_socket.connect((socket.gethostbyname(socket.gethostname()), port))
OSError: [Errno 22] Invalid argument

测试发现：循环中第一次连接会抛出ConnectionRefusedError[Errno61]（连接被拒绝），能正常捕获；但从第二次迭代开始，调用my_socket.connect((device, port))直接返回OSError[Errno22]无效参数错误，没法继续遍历其他设备，最后连本地主机也报同样的错。

环境：PyCharm 2021.1（社区版），macOS 12.5

TCP套接字对象在调用connect()失败后，会进入不可复用的错误状态，不能再用来发起新的连接请求。你只在代码开头创建了一次套接字，第一次连接失败后，这个套接字已经处于错误状态，后续再调用connect()就会直接返回无效参数的错误。

每次尝试连接前都创建一个新的套接字对象，或者在每次连接失败后关闭当前套接字并重新创建。

修改后的代码示例：

import socket
import os


devices = []
print("Looking for open server. . .")
for device in os.popen('arp -a'):
    devices.append(device.split()[1].strip("()"))  # .strip("()")
# print(devices)

make_server = True
port = 8000
for device in devices:
    # 每次循环新建套接字
    my_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    # 设置超时，避免长时间等待
    my_socket.settimeout(1)
    try:
        my_socket.connect((device, port))
        make_server = False
        print(f"Connected to {device}")
        break
    except socket.error as error:
        # 关闭失败的套接字
        my_socket.close()
        pass
        # print(error)

if make_server:
    # 新建套接字连接本地
    local_socket = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
    local_ip = socket.gethostbyname(socket.gethostname())
    try:
        local_socket.connect((local_ip, port))
        print(f"Connected to {local_ip}")
    except socket.error as e:
        print(f"Failed to connect to local: {e}")
    finally:
        local_socket.close()

内容的提问来源于stack exchange，提问作者Bug In A Rug