250 lines
8.8 KiB
Python
250 lines
8.8 KiB
Python
import sys
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if sys.platform == "win32":
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from typing import Any
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import dns.name
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_prefer_wmi = True
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import winreg # pylint: disable=import-error
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# Keep pylint quiet on non-windows.
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try:
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WindowsError is None # pylint: disable=used-before-assignment
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except KeyError:
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WindowsError = Exception
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try:
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import threading
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import pythoncom # pylint: disable=import-error
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import wmi # pylint: disable=import-error
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_have_wmi = True
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except Exception:
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_have_wmi = False
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def _config_domain(domain):
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# Sometimes DHCP servers add a '.' prefix to the default domain, and
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# Windows just stores such values in the registry (see #687).
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# Check for this and fix it.
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if domain.startswith("."):
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domain = domain[1:]
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return dns.name.from_text(domain)
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class DnsInfo:
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def __init__(self):
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self.domain = None
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self.nameservers = []
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self.search = []
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if _have_wmi:
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class _WMIGetter(threading.Thread):
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def __init__(self):
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super().__init__()
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self.info = DnsInfo()
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def run(self):
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pythoncom.CoInitialize()
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try:
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system = wmi.WMI()
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for interface in system.Win32_NetworkAdapterConfiguration():
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if interface.IPEnabled and interface.DNSDomain:
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self.info.domain = _config_domain(interface.DNSDomain)
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self.info.nameservers = list(interface.DNSServerSearchOrder)
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if interface.DNSDomainSuffixSearchOrder:
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self.info.search = [
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_config_domain(x)
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for x in interface.DNSDomainSuffixSearchOrder
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]
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break
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finally:
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pythoncom.CoUninitialize()
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def get(self):
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# We always run in a separate thread to avoid any issues with
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# the COM threading model.
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self.start()
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self.join()
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return self.info
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else:
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class _WMIGetter: # type: ignore
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pass
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class _RegistryGetter:
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def __init__(self):
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self.info = DnsInfo()
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def _determine_split_char(self, entry):
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#
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# The windows registry irritatingly changes the list element
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# delimiter in between ' ' and ',' (and vice-versa) in various
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# versions of windows.
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#
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if entry.find(" ") >= 0:
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split_char = " "
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elif entry.find(",") >= 0:
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split_char = ","
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else:
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# probably a singleton; treat as a space-separated list.
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split_char = " "
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return split_char
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def _config_nameservers(self, nameservers):
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split_char = self._determine_split_char(nameservers)
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ns_list = nameservers.split(split_char)
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for ns in ns_list:
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if ns not in self.info.nameservers:
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self.info.nameservers.append(ns)
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def _config_search(self, search):
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split_char = self._determine_split_char(search)
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search_list = search.split(split_char)
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for s in search_list:
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s = _config_domain(s)
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if s not in self.info.search:
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self.info.search.append(s)
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def _config_fromkey(self, key, always_try_domain):
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try:
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servers, _ = winreg.QueryValueEx(key, "NameServer")
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except WindowsError:
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servers = None
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if servers:
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self._config_nameservers(servers)
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if servers or always_try_domain:
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try:
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dom, _ = winreg.QueryValueEx(key, "Domain")
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if dom:
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self.info.domain = _config_domain(dom)
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except WindowsError:
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pass
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else:
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try:
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servers, _ = winreg.QueryValueEx(key, "DhcpNameServer")
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except WindowsError:
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servers = None
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if servers:
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self._config_nameservers(servers)
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try:
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dom, _ = winreg.QueryValueEx(key, "DhcpDomain")
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if dom:
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self.info.domain = _config_domain(dom)
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except WindowsError:
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pass
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try:
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search, _ = winreg.QueryValueEx(key, "SearchList")
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except WindowsError:
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search = None
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if search is None:
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try:
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search, _ = winreg.QueryValueEx(key, "DhcpSearchList")
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except WindowsError:
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search = None
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if search:
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self._config_search(search)
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def _is_nic_enabled(self, lm, guid):
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# Look in the Windows Registry to determine whether the network
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# interface corresponding to the given guid is enabled.
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#
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# (Code contributed by Paul Marks, thanks!)
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#
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try:
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# This hard-coded location seems to be consistent, at least
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# from Windows 2000 through Vista.
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connection_key = winreg.OpenKey(
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lm,
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r"SYSTEM\CurrentControlSet\Control\Network"
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r"\{4D36E972-E325-11CE-BFC1-08002BE10318}"
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r"\%s\Connection" % guid,
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)
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try:
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# The PnpInstanceID points to a key inside Enum
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(pnp_id, ttype) = winreg.QueryValueEx(
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connection_key, "PnpInstanceID"
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)
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if ttype != winreg.REG_SZ:
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raise ValueError # pragma: no cover
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device_key = winreg.OpenKey(
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lm, r"SYSTEM\CurrentControlSet\Enum\%s" % pnp_id
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)
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try:
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# Get ConfigFlags for this device
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(flags, ttype) = winreg.QueryValueEx(device_key, "ConfigFlags")
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if ttype != winreg.REG_DWORD:
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raise ValueError # pragma: no cover
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# Based on experimentation, bit 0x1 indicates that the
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# device is disabled.
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#
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# XXXRTH I suspect we really want to & with 0x03 so
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# that CONFIGFLAGS_REMOVED devices are also ignored,
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# but we're shifting to WMI as ConfigFlags is not
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# supposed to be used.
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return not flags & 0x1
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finally:
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device_key.Close()
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finally:
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connection_key.Close()
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except Exception: # pragma: no cover
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return False
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def get(self):
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"""Extract resolver configuration from the Windows registry."""
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lm = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
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try:
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tcp_params = winreg.OpenKey(
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lm, r"SYSTEM\CurrentControlSet\Services\Tcpip\Parameters"
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)
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try:
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self._config_fromkey(tcp_params, True)
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finally:
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tcp_params.Close()
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interfaces = winreg.OpenKey(
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lm,
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r"SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces",
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)
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try:
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i = 0
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while True:
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try:
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guid = winreg.EnumKey(interfaces, i)
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i += 1
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key = winreg.OpenKey(interfaces, guid)
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try:
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if not self._is_nic_enabled(lm, guid):
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continue
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self._config_fromkey(key, False)
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finally:
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key.Close()
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except EnvironmentError:
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break
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finally:
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interfaces.Close()
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finally:
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lm.Close()
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return self.info
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_getter_class: Any
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if _have_wmi and _prefer_wmi:
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_getter_class = _WMIGetter
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else:
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_getter_class = _RegistryGetter
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def get_dns_info():
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"""Extract resolver configuration."""
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getter = _getter_class()
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return getter.get()
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