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