import sys import dns._features if sys.platform == "win32": from typing import Any import dns.name _prefer_wmi = True import winreg # pylint: disable=import-error # Keep pylint quiet on non-windows. try: WindowsError is None # pylint: disable=used-before-assignment except KeyError: WindowsError = Exception if dns._features.have("wmi"): import threading import pythoncom # pylint: disable=import-error import wmi # pylint: disable=import-error _have_wmi = True else: _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 and interface.DNSServerSearchOrder: self.info.nameservers = list(interface.DNSServerSearchOrder) if interface.DNSDomain: self.info.domain = _config_domain(interface.DNSDomain) if interface.DNSDomainSuffixSearchOrder: self.info.search = [ _config_domain(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: # type: ignore 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 = _config_domain(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\Services\Tcpip\Parameters" ) try: self._config_fromkey(tcp_params, True) finally: tcp_params.Close() interfaces = winreg.OpenKey( lm, r"SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\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 _getter_class: Any 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()