在Windows上的同一端口上运行python web服务器两次：没有“端口已经在使用”消息

Question

我在Windows7上。当我启动瓶子网络服务器时：

run('0.0.0.0', port=80) 

然后，再次运行同一个Python脚本，不会因为Port already in use错误而失败（这应该是正常行为），而是再次成功地启动Python脚本！在

问题：如何以简单的方式阻止这种行为？

这与Multiple processes listening on the same port?有关，但是如何在Python上下文中防止这种情况呢？在

Answer 1

另一种解决方案是在再次打开之前使用@LuisMuñoz的评论：check if the port is already opened：

# Bottle web server code here
# ...

import socket
sock = socket.socket()
sock.settimeout(0.2)  # this prevents a 2 second lag when starting the server
if sock.connect_ex(('127.0.0.1', 80)) == 0:
    print "Sorry, port already in use."
    exit()

run(host='0.0.0.0', port=80)  

Answer 2

这是Windows特有的行为，需要在绑定网络套接字之前使用SO_EXCLUSIVEADDRUSE选项。在

从Using SO_REUSEADDR and SO_EXCLUSIVEADDRUSE article in the Windows Socket 2 documentation：

Before the SO_EXCLUSIVEADDRUSE socket option was introduced, there was very little a network application developer could do to prevent a malicious program from binding to the port on which the network application had its own sockets bound. In order to address this security issue, Windows Sockets introduced the SO_EXCLUSIVEADDRUSE socket option, which became available on Windows NT 4.0 with Service Pack 4 (SP4) and later.

...

The SO_EXCLUSIVEADDRUSE option is set by calling the setsockopt function with the optname parameter set to SO_EXCLUSIVEADDRUSE and the optval parameter set to a boolean value of TRUE before the socket is bound.

---

为了使用Bottle模块来实现这一点，您必须创建一个定制的后端，以便在绑定套接字之前访问它。这提供了一个按文档设置所需套接字选项的机会。在

这在Bottle Deployment documentation中有简要描述：

If there is no adapter for your favorite server or if you need more control over the server setup, you may want to start the server manually.

---

以下是Bottle Hello World example的修改版本，它演示了这一点：

import socket
from wsgiref.simple_server import WSGIServer
from bottle import route, run, template

@route('/hello/<name>')
def index(name):
  return template('<b>Hello {{name}}</b>!', name=name)

class CustomSocketServer(WSGIServer):
  def server_bind(self):
    # This tests if the socket option exists (i.e. only on Windows), then
    # sets it.
    if hasattr(socket, 'SO_EXCLUSIVEADDRUSE'):
      self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_EXCLUSIVEADDRUSE, 1)

    # Everything below this point is a concatenation of the server_bind
    # implementations pulled from each class in the class hierarchy.
    # wsgiref.WSGIServer -> http.HTTPServer -> socketserver.TCPServer

    elif self.allow_reuse_address:
      self.socket.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
    self.socket.bind(self.server_address)
    self.server_address = self.socket.getsockname()
    host, port = self.server_address[:2]
    self.server_name = socket.getfqdn(host)
    self.server_port = port
    self.setup_environ()

print "Serving..."
run(host='localhost', port=8080, server_class=CustomSocketServer)   

请注意，复制的代码是维护超级类的预期行为所必需的。在

server_bind()的所有超级类实现都是从调用其父类server_bind()开始的。这意味着调用它们中的任何一个都会导致立即绑定套接字，从而消除了设置所需套接字选项的机会。在

---

我用Python2.7在Windows10上测试了这一点。在

初审：

^{pr2}$

二审：

PS C:\Users\chuckx\bottle-test> C:\Python27\python.exe test.py
Traceback (most recent call last):
  File "test.py", line 32, in <module>
    server_class=CustomSocketServer)
  File "C:\Python27\lib\wsgiref\simple_server.py", line 151, in make_server
    server = server_class((host, port), handler_class)
  File "C:\Python27\lib\SocketServer.py", line 417, in __init__
    self.server_bind()
  File "test.py", line 19, in server_bind
    self.socket.bind(self.server_address)
  File "C:\Python27\lib\socket.py", line 228, in meth
    return getattr(self._sock,name)(*args)
socket.error: [Errno 10048] Only one usage of each socket address (protocol/network address/port) is normally permitted