115 lines
3.0 KiB
Python
115 lines
3.0 KiB
Python
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from fcntl import ioctl
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import subprocess
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import os
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import struct
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class TapDevice:
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""" TUN/TAP device class """
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# magic numbers and structlayout
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TUNSETIFF = 0x400454ca
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IFF_TUN = 0x0001
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IFF_TAP = 0x0002
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DEVPATH = "/dev/net/tun"
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_ifreq = "16sh"
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def __init__(self, name='', tap=True, conf=None):
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""" Constructor for the device.
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name - the device name, use a %d for a generated device numer
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tap - if this device should be a tap device
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conf - conf to pass to the ifconfig function of this class
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(if None ifconfig() won't be called)
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"""
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self._mode = (tap and self.IFF_TAP) or self.IFF_TUN
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self._fd = None
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self._name = None
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self._tap = tap
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self._mac = None
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self._mtu = 1500
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self.conf = conf
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if name == '':
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self._nametpl = (tap and "tap%d") or "tun%d"
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self._createDev()
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if self.conf:
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self.ifconfig(**conf)
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def _createDev(self):
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if self._fd:
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self.close()
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self._fd = os.open(self.DEVPATH, os.O_RDWR)
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ifreq = struct.pack(self._ifreq, self._nametpl, self._mode)
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ret = ioctl(self._fd, self.TUNSETIFF, ifreq)
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# retmode should be the same as self._mode
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(retname, retmode) = struct.unpack(self._ifreq, ret)
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self._name = retname.strip("\x00")
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def _ifconfig(self, params):
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args = ["/sbin/ifconfig"] + params
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ret = subprocess.Popen(args).wait()
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if ret != 0:
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raise PyTapException("Command '%s' did not return 0" % (" ".join(args),))
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def ifconfig(self, **kwargs):
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""" Calls ifconfig for the device.
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All arguments will be passed to ifconfig. Use 'address' for the device address.
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E.g. device.ifconfig(address="12.34.56.78", mtu=1500)
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"""
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args = [self._name]
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if kwargs.has_key("address"):
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args.append(kwargs["address"])
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del(kwargs["address"])
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args = reduce(lambda l, key: l+[key, str(kwargs[key])],
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kwargs, args)
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self._ifconfig(args)
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def getMac(self):
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""" Get the device mac """
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# this "could" be buffered, but we never know who when changed the mac
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# ==> we re-get the mac on every request
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proc = subprocess.Popen("LC_ALL=C /sbin/ifconfig %s|head -n 1|egrep -o '([0-9a-fA-F]{2}:){5}[0-9a-fA-F]{2}'" % self.getName(), shell=True, stdout=subprocess.PIPE)
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mac = proc.stdout.read().strip()
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return mac
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def up(self):
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""" Bring the device up """
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self._ifconfig([self._name, "up"])
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def down(self):
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""" Bring the device down """
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self._ifconfig([self._name, "down"])
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def getFD(self):
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""" Get the device file descriptor (e.g. to use in select()) """
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return self._fd
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def getName(self):
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""" Get the (real) name of the device """
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return self._name
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def read(self):
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""" Read a packet from the device """
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readSize = self._mtu
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if self._tap:
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# don't forget the ethernet frame (not included in MTU)
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readSize += 18
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data = os.read(self._fd, self._mtu)
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return data
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def write(self, data):
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""" Write a packet to the device """
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os.write(self._fd, data)
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def close(self):
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""" Close the device """
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os.close(self._fd)
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self._fd = self._name = None
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class PyTapException(Exception):
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pass
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