--- /dev/null
+# Copyright (C) 2003-2007, 2009, 2010 Nominum, Inc.
+#
+# Permission to use, copy, modify, and distribute this software and its
+# documentation for any purpose with or without fee is hereby granted,
+# provided that the above copyright notice and this permission notice
+# appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
+# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+"""DNS stub resolver.
+
+@var default_resolver: The default resolver object
+@type default_resolver: dns.resolver.Resolver object"""
+
+import socket
+import sys
+import time
+
+import dns.exception
+import dns.message
+import dns.name
+import dns.query
+import dns.rcode
+import dns.rdataclass
+import dns.rdatatype
+
+if sys.platform == 'win32':
+ import _winreg
+
+class NXDOMAIN(dns.exception.DNSException):
+ """The query name does not exist."""
+ pass
+
+# The definition of the Timeout exception has moved from here to the
+# dns.exception module. We keep dns.resolver.Timeout defined for
+# backwards compatibility.
+
+Timeout = dns.exception.Timeout
+
+class NoAnswer(dns.exception.DNSException):
+ """The response did not contain an answer to the question."""
+ pass
+
+class NoNameservers(dns.exception.DNSException):
+ """No non-broken nameservers are available to answer the query."""
+ pass
+
+class NotAbsolute(dns.exception.DNSException):
+ """Raised if an absolute domain name is required but a relative name
+ was provided."""
+ pass
+
+class NoRootSOA(dns.exception.DNSException):
+ """Raised if for some reason there is no SOA at the root name.
+ This should never happen!"""
+ pass
+
+
+class Answer(object):
+ """DNS stub resolver answer
+
+ Instances of this class bundle up the result of a successful DNS
+ resolution.
+
+ For convenience, the answer object implements much of the sequence
+ protocol, forwarding to its rrset. E.g. "for a in answer" is
+ equivalent to "for a in answer.rrset", "answer[i]" is equivalent
+ to "answer.rrset[i]", and "answer[i:j]" is equivalent to
+ "answer.rrset[i:j]".
+
+ Note that CNAMEs or DNAMEs in the response may mean that answer
+ node's name might not be the query name.
+
+ @ivar qname: The query name
+ @type qname: dns.name.Name object
+ @ivar rdtype: The query type
+ @type rdtype: int
+ @ivar rdclass: The query class
+ @type rdclass: int
+ @ivar response: The response message
+ @type response: dns.message.Message object
+ @ivar rrset: The answer
+ @type rrset: dns.rrset.RRset object
+ @ivar expiration: The time when the answer expires
+ @type expiration: float (seconds since the epoch)
+ """
+ def __init__(self, qname, rdtype, rdclass, response):
+ self.qname = qname
+ self.rdtype = rdtype
+ self.rdclass = rdclass
+ self.response = response
+ min_ttl = -1
+ rrset = None
+ for count in xrange(0, 15):
+ try:
+ rrset = response.find_rrset(response.answer, qname,
+ rdclass, rdtype)
+ if min_ttl == -1 or rrset.ttl < min_ttl:
+ min_ttl = rrset.ttl
+ break
+ except KeyError:
+ if rdtype != dns.rdatatype.CNAME:
+ try:
+ crrset = response.find_rrset(response.answer,
+ qname,
+ rdclass,
+ dns.rdatatype.CNAME)
+ if min_ttl == -1 or crrset.ttl < min_ttl:
+ min_ttl = crrset.ttl
+ for rd in crrset:
+ qname = rd.target
+ break
+ continue
+ except KeyError:
+ raise NoAnswer
+ raise NoAnswer
+ if rrset is None:
+ raise NoAnswer
+ self.rrset = rrset
+ self.expiration = time.time() + min_ttl
+
+ def __getattr__(self, attr):
+ if attr == 'name':
+ return self.rrset.name
+ elif attr == 'ttl':
+ return self.rrset.ttl
+ elif attr == 'covers':
+ return self.rrset.covers
+ elif attr == 'rdclass':
+ return self.rrset.rdclass
+ elif attr == 'rdtype':
+ return self.rrset.rdtype
+ else:
+ raise AttributeError(attr)
+
+ def __len__(self):
+ return len(self.rrset)
+
+ def __iter__(self):
+ return iter(self.rrset)
+
+ def __getitem__(self, i):
+ return self.rrset[i]
+
+ def __delitem__(self, i):
+ del self.rrset[i]
+
+ def __getslice__(self, i, j):
+ return self.rrset[i:j]
+
+ def __delslice__(self, i, j):
+ del self.rrset[i:j]
+
+class Cache(object):
+ """Simple DNS answer cache.
+
+ @ivar data: A dictionary of cached data
+ @type data: dict
+ @ivar cleaning_interval: The number of seconds between cleanings. The
+ default is 300 (5 minutes).
+ @type cleaning_interval: float
+ @ivar next_cleaning: The time the cache should next be cleaned (in seconds
+ since the epoch.)
+ @type next_cleaning: float
+ """
+
+ def __init__(self, cleaning_interval=300.0):
+ """Initialize a DNS cache.
+
+ @param cleaning_interval: the number of seconds between periodic
+ cleanings. The default is 300.0
+ @type cleaning_interval: float.
+ """
+
+ self.data = {}
+ self.cleaning_interval = cleaning_interval
+ self.next_cleaning = time.time() + self.cleaning_interval
+
+ def maybe_clean(self):
+ """Clean the cache if it's time to do so."""
+
+ now = time.time()
+ if self.next_cleaning <= now:
+ keys_to_delete = []
+ for (k, v) in self.data.iteritems():
+ if v.expiration <= now:
+ keys_to_delete.append(k)
+ for k in keys_to_delete:
+ del self.data[k]
+ now = time.time()
+ self.next_cleaning = now + self.cleaning_interval
+
+ def get(self, key):
+ """Get the answer associated with I{key}. Returns None if
+ no answer is cached for the key.
+ @param key: the key
+ @type key: (dns.name.Name, int, int) tuple whose values are the
+ query name, rdtype, and rdclass.
+ @rtype: dns.resolver.Answer object or None
+ """
+
+ self.maybe_clean()
+ v = self.data.get(key)
+ if v is None or v.expiration <= time.time():
+ return None
+ return v
+
+ def put(self, key, value):
+ """Associate key and value in the cache.
+ @param key: the key
+ @type key: (dns.name.Name, int, int) tuple whose values are the
+ query name, rdtype, and rdclass.
+ @param value: The answer being cached
+ @type value: dns.resolver.Answer object
+ """
+
+ self.maybe_clean()
+ self.data[key] = value
+
+ def flush(self, key=None):
+ """Flush the cache.
+
+ If I{key} is specified, only that item is flushed. Otherwise
+ the entire cache is flushed.
+
+ @param key: the key to flush
+ @type key: (dns.name.Name, int, int) tuple or None
+ """
+
+ if not key is None:
+ if self.data.has_key(key):
+ del self.data[key]
+ else:
+ self.data = {}
+ self.next_cleaning = time.time() + self.cleaning_interval
+
+class Resolver(object):
+ """DNS stub resolver
+
+ @ivar domain: The domain of this host
+ @type domain: dns.name.Name object
+ @ivar nameservers: A list of nameservers to query. Each nameserver is
+ a string which contains the IP address of a nameserver.
+ @type nameservers: list of strings
+ @ivar search: The search list. If the query name is a relative name,
+ the resolver will construct an absolute query name by appending the search
+ names one by one to the query name.
+ @type search: list of dns.name.Name objects
+ @ivar port: The port to which to send queries. The default is 53.
+ @type port: int
+ @ivar timeout: The number of seconds to wait for a response from a
+ server, before timing out.
+ @type timeout: float
+ @ivar lifetime: The total number of seconds to spend trying to get an
+ answer to the question. If the lifetime expires, a Timeout exception
+ will occur.
+ @type lifetime: float
+ @ivar keyring: The TSIG keyring to use. The default is None.
+ @type keyring: dict
+ @ivar keyname: The TSIG keyname to use. The default is None.
+ @type keyname: dns.name.Name object
+ @ivar keyalgorithm: The TSIG key algorithm to use. The default is
+ dns.tsig.default_algorithm.
+ @type keyalgorithm: string
+ @ivar edns: The EDNS level to use. The default is -1, no Edns.
+ @type edns: int
+ @ivar ednsflags: The EDNS flags
+ @type ednsflags: int
+ @ivar payload: The EDNS payload size. The default is 0.
+ @type payload: int
+ @ivar cache: The cache to use. The default is None.
+ @type cache: dns.resolver.Cache object
+ """
+ def __init__(self, filename='/etc/resolv.conf', configure=True):
+ """Initialize a resolver instance.
+
+ @param filename: The filename of a configuration file in
+ standard /etc/resolv.conf format. This parameter is meaningful
+ only when I{configure} is true and the platform is POSIX.
+ @type filename: string or file object
+ @param configure: If True (the default), the resolver instance
+ is configured in the normal fashion for the operating system
+ the resolver is running on. (I.e. a /etc/resolv.conf file on
+ POSIX systems and from the registry on Windows systems.)
+ @type configure: bool"""
+
+ self.reset()
+ if configure:
+ if sys.platform == 'win32':
+ self.read_registry()
+ elif filename:
+ self.read_resolv_conf(filename)
+
+ def reset(self):
+ """Reset all resolver configuration to the defaults."""
+ self.domain = \
+ dns.name.Name(dns.name.from_text(socket.gethostname())[1:])
+ if len(self.domain) == 0:
+ self.domain = dns.name.root
+ self.nameservers = []
+ self.search = []
+ self.port = 53
+ self.timeout = 2.0
+ self.lifetime = 30.0
+ self.keyring = None
+ self.keyname = None
+ self.keyalgorithm = dns.tsig.default_algorithm
+ self.edns = -1
+ self.ednsflags = 0
+ self.payload = 0
+ self.cache = None
+
+ def read_resolv_conf(self, f):
+ """Process f as a file in the /etc/resolv.conf format. If f is
+ a string, it is used as the name of the file to open; otherwise it
+ is treated as the file itself."""
+ if isinstance(f, str) or isinstance(f, unicode):
+ try:
+ f = open(f, 'r')
+ except IOError:
+ # /etc/resolv.conf doesn't exist, can't be read, etc.
+ # We'll just use the default resolver configuration.
+ self.nameservers = ['127.0.0.1']
+ return
+ want_close = True
+ else:
+ want_close = False
+ try:
+ for l in f:
+ if len(l) == 0 or l[0] == '#' or l[0] == ';':
+ continue
+ tokens = l.split()
+ if len(tokens) == 0:
+ continue
+ if tokens[0] == 'nameserver':
+ self.nameservers.append(tokens[1])
+ elif tokens[0] == 'domain':
+ self.domain = dns.name.from_text(tokens[1])
+ elif tokens[0] == 'search':
+ for suffix in tokens[1:]:
+ self.search.append(dns.name.from_text(suffix))
+ finally:
+ if want_close:
+ f.close()
+ if len(self.nameservers) == 0:
+ self.nameservers.append('127.0.0.1')
+
+ 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_win32_nameservers(self, nameservers):
+ """Configure a NameServer registry entry."""
+ # we call str() on nameservers to convert it from unicode to ascii
+ nameservers = str(nameservers)
+ split_char = self._determine_split_char(nameservers)
+ ns_list = nameservers.split(split_char)
+ for ns in ns_list:
+ if not ns in self.nameservers:
+ self.nameservers.append(ns)
+
+ def _config_win32_domain(self, domain):
+ """Configure a Domain registry entry."""
+ # we call str() on domain to convert it from unicode to ascii
+ self.domain = dns.name.from_text(str(domain))
+
+ def _config_win32_search(self, search):
+ """Configure a Search registry entry."""
+ # we call str() on search to convert it from unicode to ascii
+ search = str(search)
+ split_char = self._determine_split_char(search)
+ search_list = search.split(split_char)
+ for s in search_list:
+ if not s in self.search:
+ self.search.append(dns.name.from_text(s))
+
+ def _config_win32_fromkey(self, key):
+ """Extract DNS info from a registry key."""
+ try:
+ servers, rtype = _winreg.QueryValueEx(key, 'NameServer')
+ except WindowsError:
+ servers = None
+ if servers:
+ self._config_win32_nameservers(servers)
+ try:
+ dom, rtype = _winreg.QueryValueEx(key, 'Domain')
+ if dom:
+ self._config_win32_domain(dom)
+ except WindowsError:
+ pass
+ else:
+ try:
+ servers, rtype = _winreg.QueryValueEx(key, 'DhcpNameServer')
+ except WindowsError:
+ servers = None
+ if servers:
+ self._config_win32_nameservers(servers)
+ try:
+ dom, rtype = _winreg.QueryValueEx(key, 'DhcpDomain')
+ if dom:
+ self._config_win32_domain(dom)
+ except WindowsError:
+ pass
+ try:
+ search, rtype = _winreg.QueryValueEx(key, 'SearchList')
+ except WindowsError:
+ search = None
+ if search:
+ self._config_win32_search(search)
+
+ def read_registry(self):
+ """Extract resolver configuration from the Windows registry."""
+ lm = _winreg.ConnectRegistry(None, _winreg.HKEY_LOCAL_MACHINE)
+ want_scan = False
+ try:
+ try:
+ # XP, 2000
+ tcp_params = _winreg.OpenKey(lm,
+ r'SYSTEM\CurrentControlSet'
+ r'\Services\Tcpip\Parameters')
+ want_scan = True
+ except EnvironmentError:
+ # ME
+ tcp_params = _winreg.OpenKey(lm,
+ r'SYSTEM\CurrentControlSet'
+ r'\Services\VxD\MSTCP')
+ try:
+ self._config_win32_fromkey(tcp_params)
+ finally:
+ tcp_params.Close()
+ if want_scan:
+ 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)
+ if not self._win32_is_nic_enabled(lm, guid, key):
+ continue
+ try:
+ self._config_win32_fromkey(key)
+ finally:
+ key.Close()
+ except EnvironmentError:
+ break
+ finally:
+ interfaces.Close()
+ finally:
+ lm.Close()
+
+ def _win32_is_nic_enabled(self, lm, guid, interface_key):
+ # 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
+
+ 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
+
+ # Based on experimentation, bit 0x1 indicates that the
+ # device is disabled.
+ return not (flags & 0x1)
+
+ finally:
+ device_key.Close()
+ finally:
+ connection_key.Close()
+ except (EnvironmentError, ValueError):
+ # Pre-vista, enabled interfaces seem to have a non-empty
+ # NTEContextList; this was how dnspython detected enabled
+ # nics before the code above was contributed. We've retained
+ # the old method since we don't know if the code above works
+ # on Windows 95/98/ME.
+ try:
+ (nte, ttype) = _winreg.QueryValueEx(interface_key,
+ 'NTEContextList')
+ return nte is not None
+ except WindowsError:
+ return False
+
+ def _compute_timeout(self, start):
+ now = time.time()
+ if now < start:
+ if start - now > 1:
+ # Time going backwards is bad. Just give up.
+ raise Timeout
+ else:
+ # Time went backwards, but only a little. This can
+ # happen, e.g. under vmware with older linux kernels.
+ # Pretend it didn't happen.
+ now = start
+ duration = now - start
+ if duration >= self.lifetime:
+ raise Timeout
+ return min(self.lifetime - duration, self.timeout)
+
+ def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
+ tcp=False, source=None):
+ """Query nameservers to find the answer to the question.
+
+ The I{qname}, I{rdtype}, and I{rdclass} parameters may be objects
+ of the appropriate type, or strings that can be converted into objects
+ of the appropriate type. E.g. For I{rdtype} the integer 2 and the
+ the string 'NS' both mean to query for records with DNS rdata type NS.
+
+ @param qname: the query name
+ @type qname: dns.name.Name object or string
+ @param rdtype: the query type
+ @type rdtype: int or string
+ @param rdclass: the query class
+ @type rdclass: int or string
+ @param tcp: use TCP to make the query (default is False).
+ @type tcp: bool
+ @param source: bind to this IP address (defaults to machine default IP).
+ @type source: IP address in dotted quad notation
+ @rtype: dns.resolver.Answer instance
+ @raises Timeout: no answers could be found in the specified lifetime
+ @raises NXDOMAIN: the query name does not exist
+ @raises NoAnswer: the response did not contain an answer
+ @raises NoNameservers: no non-broken nameservers are available to
+ answer the question."""
+
+ if isinstance(qname, (str, unicode)):
+ qname = dns.name.from_text(qname, None)
+ if isinstance(rdtype, str):
+ rdtype = dns.rdatatype.from_text(rdtype)
+ if isinstance(rdclass, str):
+ rdclass = dns.rdataclass.from_text(rdclass)
+ qnames_to_try = []
+ if qname.is_absolute():
+ qnames_to_try.append(qname)
+ else:
+ if len(qname) > 1:
+ qnames_to_try.append(qname.concatenate(dns.name.root))
+ if self.search:
+ for suffix in self.search:
+ qnames_to_try.append(qname.concatenate(suffix))
+ else:
+ qnames_to_try.append(qname.concatenate(self.domain))
+ all_nxdomain = True
+ start = time.time()
+ for qname in qnames_to_try:
+ if self.cache:
+ answer = self.cache.get((qname, rdtype, rdclass))
+ if answer:
+ return answer
+ request = dns.message.make_query(qname, rdtype, rdclass)
+ if not self.keyname is None:
+ request.use_tsig(self.keyring, self.keyname, self.keyalgorithm)
+ request.use_edns(self.edns, self.ednsflags, self.payload)
+ response = None
+ #
+ # make a copy of the servers list so we can alter it later.
+ #
+ nameservers = self.nameservers[:]
+ backoff = 0.10
+ while response is None:
+ if len(nameservers) == 0:
+ raise NoNameservers
+ for nameserver in nameservers[:]:
+ timeout = self._compute_timeout(start)
+ try:
+ if tcp:
+ response = dns.query.tcp(request, nameserver,
+ timeout, self.port,
+ source=source)
+ else:
+ response = dns.query.udp(request, nameserver,
+ timeout, self.port,
+ source=source)
+ except (socket.error, dns.exception.Timeout):
+ #
+ # Communication failure or timeout. Go to the
+ # next server
+ #
+ response = None
+ continue
+ except dns.query.UnexpectedSource:
+ #
+ # Who knows? Keep going.
+ #
+ response = None
+ continue
+ except dns.exception.FormError:
+ #
+ # We don't understand what this server is
+ # saying. Take it out of the mix and
+ # continue.
+ #
+ nameservers.remove(nameserver)
+ response = None
+ continue
+ rcode = response.rcode()
+ if rcode == dns.rcode.NOERROR or \
+ rcode == dns.rcode.NXDOMAIN:
+ break
+ #
+ # We got a response, but we're not happy with the
+ # rcode in it. Remove the server from the mix if
+ # the rcode isn't SERVFAIL.
+ #
+ if rcode != dns.rcode.SERVFAIL:
+ nameservers.remove(nameserver)
+ response = None
+ if not response is None:
+ break
+ #
+ # All nameservers failed!
+ #
+ if len(nameservers) > 0:
+ #
+ # But we still have servers to try. Sleep a bit
+ # so we don't pound them!
+ #
+ timeout = self._compute_timeout(start)
+ sleep_time = min(timeout, backoff)
+ backoff *= 2
+ time.sleep(sleep_time)
+ if response.rcode() == dns.rcode.NXDOMAIN:
+ continue
+ all_nxdomain = False
+ break
+ if all_nxdomain:
+ raise NXDOMAIN
+ answer = Answer(qname, rdtype, rdclass, response)
+ if self.cache:
+ self.cache.put((qname, rdtype, rdclass), answer)
+ return answer
+
+ def use_tsig(self, keyring, keyname=None,
+ algorithm=dns.tsig.default_algorithm):
+ """Add a TSIG signature to the query.
+
+ @param keyring: The TSIG keyring to use; defaults to None.
+ @type keyring: dict
+ @param keyname: The name of the TSIG key to use; defaults to None.
+ The key must be defined in the keyring. If a keyring is specified
+ but a keyname is not, then the key used will be the first key in the
+ keyring. Note that the order of keys in a dictionary is not defined,
+ so applications should supply a keyname when a keyring is used, unless
+ they know the keyring contains only one key.
+ @param algorithm: The TSIG key algorithm to use. The default
+ is dns.tsig.default_algorithm.
+ @type algorithm: string"""
+ self.keyring = keyring
+ if keyname is None:
+ self.keyname = self.keyring.keys()[0]
+ else:
+ self.keyname = keyname
+ self.keyalgorithm = algorithm
+
+ def use_edns(self, edns, ednsflags, payload):
+ """Configure Edns.
+
+ @param edns: The EDNS level to use. The default is -1, no Edns.
+ @type edns: int
+ @param ednsflags: The EDNS flags
+ @type ednsflags: int
+ @param payload: The EDNS payload size. The default is 0.
+ @type payload: int"""
+
+ if edns is None:
+ edns = -1
+ self.edns = edns
+ self.ednsflags = ednsflags
+ self.payload = payload
+
+default_resolver = None
+
+def get_default_resolver():
+ """Get the default resolver, initializing it if necessary."""
+ global default_resolver
+ if default_resolver is None:
+ default_resolver = Resolver()
+ return default_resolver
+
+def query(qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
+ tcp=False, source=None):
+ """Query nameservers to find the answer to the question.
+
+ This is a convenience function that uses the default resolver
+ object to make the query.
+ @see: L{dns.resolver.Resolver.query} for more information on the
+ parameters."""
+ return get_default_resolver().query(qname, rdtype, rdclass, tcp, source)
+
+def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None):
+ """Find the name of the zone which contains the specified name.
+
+ @param name: the query name
+ @type name: absolute dns.name.Name object or string
+ @param rdclass: The query class
+ @type rdclass: int
+ @param tcp: use TCP to make the query (default is False).
+ @type tcp: bool
+ @param resolver: the resolver to use
+ @type resolver: dns.resolver.Resolver object or None
+ @rtype: dns.name.Name"""
+
+ if isinstance(name, (str, unicode)):
+ name = dns.name.from_text(name, dns.name.root)
+ if resolver is None:
+ resolver = get_default_resolver()
+ if not name.is_absolute():
+ raise NotAbsolute(name)
+ while 1:
+ try:
+ answer = resolver.query(name, dns.rdatatype.SOA, rdclass, tcp)
+ return name
+ except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
+ try:
+ name = name.parent()
+ except dns.name.NoParent:
+ raise NoRootSOA
git.samba.org / samba.git / blobdiff