使用 NetworkManager 和 Python 断开 WiFi 接入点

Posted 2023-04-14

【中文标题】使用 NetworkManager 和 Python 断开 WiFi 接入点

【英文标题】：Disconnect a WiFi access point using NetworkManager and Python

【发布时间】：2012-02-14 20:20:04

【问题描述】：

我正在构建一个 Python 应用程序，它必须在 linux 机器上连接和断开 Wifi。我正在使用 NetworkManager 层，通过在 cnetworkmanager（NetworkManager http://vidner.net/martin/software/cnetworkmanager/thanx to Martin Vidner 的 Python CLI）中找到的不错的 networkmanager 库，在一个守护进程（名为 stationd）中。 这个守护进程运行一个 gobject.MainLoop。一旦 timeout_add_seconds 唤醒（由用户在 GUI 中的操作触发），我必须断开当前正在运行的 Wifi 并连接到一个新的：

from dbus.mainloop.glib import DBusGMainLoop
DBusGMainLoop(set_as_default=True)

from networkmanager import NetworkManager
import networkmanager.applet.settings as settings
from networkmanager.applet import USER_SERVICE 
from networkmanager.applet.service import NetworkManagerUserSettings, NetworkManagerSettings
import time
import memcache

import gobject
loop = gobject.MainLoop()

nm = NetworkManager()

dummy_handler = lambda *args: None

cache = memcache.Client(['127.0.0.1:11211',] )


def get_device(dev_spec, hint):
    candidates = []
    devs = NetworkManager().GetDevices()
    for dev in devs:
        if dev._settings_type() == hint:
            candidates.append(dev)
    if len(candidates) == 1:
        return candidates[0]
    for dev in devs:
        if dev["Interface"] == dev_spec:
            return dev
    print "Device '%s' not found" % dev_spec
    return None

def kill_allconnections():
    connections=nm['ActiveConnections']
    for c in connections:
        print c.object_path
        nm.DeactivateConnection(c.object_path)

class Wifi(object):

    def connect(self, ssid, security="open", password=None):
        "Connects to given Wifi network"
        c=None # connection settings
        us = NetworkManagerUserSettings([])
        if security=="open":
            c = settings.WiFi(ssid)
        elif security=="wep":
            c = settings.Wep(ssid, password)
        elif security=="wpa":
            c = settings.WpaPsk(ssid, password)
        else:
            raise AttributeError("invalid security model '%s'"%security)
        svc = USER_SERVICE
        svc_conn = us.addCon(c.conmap)
        hint = svc_conn.settings["connection"]["type"]
        dev = get_device("", hint)
        appath = "/"
        nm.ActivateConnection(svc, svc_conn, dev, appath, reply_handler=dummy_handler, error_handler=dummy_handler)


def change_network_settings():
    key="station:network:change"
    change=cache.get(key)
    if change is not None:
        print "DISCONNECT"
        kill_allconnections()
        print "CHANGE SETTINGS"
        wifi=cache.get(key+':wifi')
        if wifi is not None:
            ssid=cache.get(key+':wifi:ssid')
            security=cache.get(key+':wifi:security')
            password=cache.get(key+':wifi:password')
            print "SWITCHING TO %s"%ssid
            Wifi().connect(ssid, security, password)
        cache.delete(key)
    return True    

def mainloop():
   gobject.timeout_add_seconds(1, change_network_settings)
   try:
      loop.run()
   except KeyboardInterrupt:
      loop.quit()

if __name__=="__main__":
    mainloop()

这对于第一次连接运行完美（阅读：盒子未连接，守护程序运行并且盒子完美连接到 Wifi）。问题是当我尝试连接到另一个 Wifi 时：kill_allconnections() 静默运行，connect 方法在 nm.ActivateConnection 上引发异常：

Traceback (most recent call last):
  File "stationd.py", line 40, in change_network_settings
    Wifi().connect(ssid, security, password)
  File "/home/biopredictive/station/lib/network.py", line 88, in connect
    us = NetworkManagerUserSettings([])
  File "/home/biopredictive/station/lib/networkmanager/applet/service/__init__.py", line 71, in __init__
    super(NetworkManagerUserSettings, self).__init__(conmaps, USER_SERVICE)
  File "/home/biopredictive/station/lib/networkmanager/applet/service/__init__.py", line 33, in __init__
    dbus.service.Object.__init__(self, bus, opath, bus_name)
  File "/usr/lib/pymodules/python2.6/dbus/service.py", line 480, in __init__
    self.add_to_connection(conn, object_path)
  File "/usr/lib/pymodules/python2.6/dbus/service.py", line 571, in add_to_connection
    self._fallback)
KeyError: "Can't register the object-path handler for '/org/freedesktop/NetworkManagerSettings': there is already a handler"

看起来我以前的连接没有释放它的所有资源？ 我对 gobject/dbus 编程非常陌生。你能帮忙吗？

【参考方案1】：

我在 D-Bus 邮件列表中有answered。在此引用存档：

class Wifi(...):
    def connect(...):
        ...
        us = NetworkManagerUserSettings([]) 

NetworkManagerUserSettings 是服务器，而不是客户端。 （这是一个设计 NM 的怪癖在 NM 0.9 中被消除） 您应该只为守护进程创建一个，而不是为每个连接创建一个 尝试。