使用NetworkManager和Python断开WiFi接入点
我正在开发一个Python应用程序，它需要在Linux系统上连接和断开Wifi。我使用的是NetworkManager这个工具，通过一个叫cnetworkmanager的Python命令行工具（感谢Martin Vidner提供的这个工具，链接在这里：http://vidner.net/martin/software/cnetworkmanager/），这个工具在一个叫stationd的守护进程中运行。
这个守护进程运行着一个gobject.MainLoop。当用户在图形界面上进行某个操作时，timeout_add_seconds会被触发，这时我需要断开当前的Wifi连接，并连接到新的Wifi。
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()
这个过程在第一次连接时运行得非常顺利（也就是说，设备最开始没有连接，守护进程启动后，设备顺利连接上了Wifi）。但是当我尝试连接到另一个Wifi时，kill_allconnections()这个方法静默运行，而connect方法在nm.ActivateConnection时却抛出了一个异常。
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"
看起来我之前的连接没有释放所有的资源？我对gobject/dbus编程还很陌生。能请你帮帮我吗？
1 个回答
3
我在D-Bus的邮件列表上有过一个回答。这里引用一下，方便存档：
class Wifi(...):
def connect(...):
...
us = NetworkManagerUserSettings([])
NetworkManagerUserSettings是一个服务器，而不是客户端。（这是NM的一个设计小问题，在NM 0.9版本中已经解决）你只需要为守护进程创建一个，而不是为每次连接尝试都创建一个。