You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
1576 lines
57 KiB
1576 lines
57 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
|
|
|
|
# Copyright (C) 2003-2017 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."""
|
|
from urllib.parse import urlparse
|
|
import contextlib
|
|
import socket
|
|
import sys
|
|
import time
|
|
import random
|
|
import warnings
|
|
try:
|
|
import threading as _threading
|
|
except ImportError: # pragma: no cover
|
|
import dummy_threading as _threading # type: ignore
|
|
|
|
import dns.exception
|
|
import dns.flags
|
|
import dns.inet
|
|
import dns.ipv4
|
|
import dns.ipv6
|
|
import dns.message
|
|
import dns.name
|
|
import dns.query
|
|
import dns.rcode
|
|
import dns.rdataclass
|
|
import dns.rdatatype
|
|
import dns.reversename
|
|
import dns.tsig
|
|
|
|
if sys.platform == 'win32':
|
|
import dns.win32util
|
|
|
|
class NXDOMAIN(dns.exception.DNSException):
|
|
"""The DNS query name does not exist."""
|
|
supp_kwargs = {'qnames', 'responses'}
|
|
fmt = None # we have our own __str__ implementation
|
|
|
|
# pylint: disable=arguments-differ
|
|
|
|
def _check_kwargs(self, qnames,
|
|
responses=None):
|
|
if not isinstance(qnames, (list, tuple, set)):
|
|
raise AttributeError("qnames must be a list, tuple or set")
|
|
if len(qnames) == 0:
|
|
raise AttributeError("qnames must contain at least one element")
|
|
if responses is None:
|
|
responses = {}
|
|
elif not isinstance(responses, dict):
|
|
raise AttributeError("responses must be a dict(qname=response)")
|
|
kwargs = dict(qnames=qnames, responses=responses)
|
|
return kwargs
|
|
|
|
def __str__(self):
|
|
if 'qnames' not in self.kwargs:
|
|
return super().__str__()
|
|
qnames = self.kwargs['qnames']
|
|
if len(qnames) > 1:
|
|
msg = 'None of DNS query names exist'
|
|
else:
|
|
msg = 'The DNS query name does not exist'
|
|
qnames = ', '.join(map(str, qnames))
|
|
return "{}: {}".format(msg, qnames)
|
|
|
|
@property
|
|
def canonical_name(self):
|
|
"""Return the unresolved canonical name."""
|
|
if 'qnames' not in self.kwargs:
|
|
raise TypeError("parametrized exception required")
|
|
for qname in self.kwargs['qnames']:
|
|
response = self.kwargs['responses'][qname]
|
|
try:
|
|
cname = response.canonical_name()
|
|
if cname != qname:
|
|
return cname
|
|
except Exception:
|
|
# We can just eat this exception as it means there was
|
|
# something wrong with the response.
|
|
pass
|
|
return self.kwargs['qnames'][0]
|
|
|
|
def __add__(self, e_nx):
|
|
"""Augment by results from another NXDOMAIN exception."""
|
|
qnames0 = list(self.kwargs.get('qnames', []))
|
|
responses0 = dict(self.kwargs.get('responses', {}))
|
|
responses1 = e_nx.kwargs.get('responses', {})
|
|
for qname1 in e_nx.kwargs.get('qnames', []):
|
|
if qname1 not in qnames0:
|
|
qnames0.append(qname1)
|
|
if qname1 in responses1:
|
|
responses0[qname1] = responses1[qname1]
|
|
return NXDOMAIN(qnames=qnames0, responses=responses0)
|
|
|
|
def qnames(self):
|
|
"""All of the names that were tried.
|
|
|
|
Returns a list of ``dns.name.Name``.
|
|
"""
|
|
return self.kwargs['qnames']
|
|
|
|
def responses(self):
|
|
"""A map from queried names to their NXDOMAIN responses.
|
|
|
|
Returns a dict mapping a ``dns.name.Name`` to a
|
|
``dns.message.Message``.
|
|
"""
|
|
return self.kwargs['responses']
|
|
|
|
def response(self, qname):
|
|
"""The response for query *qname*.
|
|
|
|
Returns a ``dns.message.Message``.
|
|
"""
|
|
return self.kwargs['responses'][qname]
|
|
|
|
|
|
class YXDOMAIN(dns.exception.DNSException):
|
|
"""The DNS query name is too long after DNAME substitution."""
|
|
|
|
|
|
def _errors_to_text(errors):
|
|
"""Turn a resolution errors trace into a list of text."""
|
|
texts = []
|
|
for err in errors:
|
|
texts.append('Server {} {} port {} answered {}'.format(err[0],
|
|
'TCP' if err[1] else 'UDP', err[2], err[3]))
|
|
return texts
|
|
|
|
|
|
class LifetimeTimeout(dns.exception.Timeout):
|
|
"""The resolution lifetime expired."""
|
|
|
|
msg = "The resolution lifetime expired."
|
|
fmt = "%s after {timeout:.3f} seconds: {errors}" % msg[:-1]
|
|
supp_kwargs = {'timeout', 'errors'}
|
|
|
|
def _fmt_kwargs(self, **kwargs):
|
|
srv_msgs = _errors_to_text(kwargs['errors'])
|
|
return super()._fmt_kwargs(timeout=kwargs['timeout'],
|
|
errors='; '.join(srv_msgs))
|
|
|
|
|
|
# We added more detail to resolution timeouts, but they are still
|
|
# subclasses of dns.exception.Timeout for backwards compatibility. We also
|
|
# keep dns.resolver.Timeout defined for backwards compatibility.
|
|
Timeout = LifetimeTimeout
|
|
|
|
|
|
class NoAnswer(dns.exception.DNSException):
|
|
"""The DNS response does not contain an answer to the question."""
|
|
fmt = 'The DNS response does not contain an answer ' + \
|
|
'to the question: {query}'
|
|
supp_kwargs = {'response'}
|
|
|
|
def _fmt_kwargs(self, **kwargs):
|
|
return super()._fmt_kwargs(query=kwargs['response'].question)
|
|
|
|
def response(self):
|
|
return self.kwargs['response']
|
|
|
|
|
|
class NoNameservers(dns.exception.DNSException):
|
|
"""All nameservers failed to answer the query.
|
|
|
|
errors: list of servers and respective errors
|
|
The type of errors is
|
|
[(server IP address, any object convertible to string)].
|
|
Non-empty errors list will add explanatory message ()
|
|
"""
|
|
|
|
msg = "All nameservers failed to answer the query."
|
|
fmt = "%s {query}: {errors}" % msg[:-1]
|
|
supp_kwargs = {'request', 'errors'}
|
|
|
|
def _fmt_kwargs(self, **kwargs):
|
|
srv_msgs = _errors_to_text(kwargs['errors'])
|
|
return super()._fmt_kwargs(query=kwargs['request'].question,
|
|
errors='; '.join(srv_msgs))
|
|
|
|
|
|
class NotAbsolute(dns.exception.DNSException):
|
|
"""An absolute domain name is required but a relative name was provided."""
|
|
|
|
|
|
class NoRootSOA(dns.exception.DNSException):
|
|
"""There is no SOA RR at the DNS root name. This should never happen!"""
|
|
|
|
|
|
class NoMetaqueries(dns.exception.DNSException):
|
|
"""DNS metaqueries are not allowed."""
|
|
|
|
class NoResolverConfiguration(dns.exception.DNSException):
|
|
"""Resolver configuration could not be read or specified no nameservers."""
|
|
|
|
class Answer:
|
|
"""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`` attribute. 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
|
|
RRset's name might not be the query name.
|
|
"""
|
|
|
|
def __init__(self, qname, rdtype, rdclass, response, nameserver=None,
|
|
port=None):
|
|
self.qname = qname
|
|
self.rdtype = rdtype
|
|
self.rdclass = rdclass
|
|
self.response = response
|
|
self.nameserver = nameserver
|
|
self.port = port
|
|
self.chaining_result = response.resolve_chaining()
|
|
# Copy some attributes out of chaining_result for backwards
|
|
# compatibility and convenience.
|
|
self.canonical_name = self.chaining_result.canonical_name
|
|
self.rrset = self.chaining_result.answer
|
|
self.expiration = time.time() + self.chaining_result.minimum_ttl
|
|
|
|
def __getattr__(self, attr): # pragma: no cover
|
|
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 self.rrset and len(self.rrset) or 0
|
|
|
|
def __iter__(self):
|
|
return self.rrset and iter(self.rrset) or iter(tuple())
|
|
|
|
def __getitem__(self, i):
|
|
if self.rrset is None:
|
|
raise IndexError
|
|
return self.rrset[i]
|
|
|
|
def __delitem__(self, i):
|
|
if self.rrset is None:
|
|
raise IndexError
|
|
del self.rrset[i]
|
|
|
|
|
|
class CacheStatistics:
|
|
"""Cache Statistics
|
|
"""
|
|
|
|
def __init__(self, hits=0, misses=0):
|
|
self.hits = hits
|
|
self.misses = misses
|
|
|
|
def reset(self):
|
|
self.hits = 0
|
|
self.misses = 0
|
|
|
|
def clone(self):
|
|
return CacheStatistics(self.hits, self.misses)
|
|
|
|
|
|
class CacheBase:
|
|
def __init__(self):
|
|
self.lock = _threading.Lock()
|
|
self.statistics = CacheStatistics()
|
|
|
|
def reset_statistics(self):
|
|
"""Reset all statistics to zero."""
|
|
with self.lock:
|
|
self.statistics.reset()
|
|
|
|
def hits(self):
|
|
"""How many hits has the cache had?"""
|
|
with self.lock:
|
|
return self.statistics.hits
|
|
|
|
def misses(self):
|
|
"""How many misses has the cache had?"""
|
|
with self.lock:
|
|
return self.statistics.misses
|
|
|
|
def get_statistics_snapshot(self):
|
|
"""Return a consistent snapshot of all the statistics.
|
|
|
|
If running with multiple threads, it's better to take a
|
|
snapshot than to call statistics methods such as hits() and
|
|
misses() individually.
|
|
"""
|
|
with self.lock:
|
|
return self.statistics.clone()
|
|
|
|
|
|
class Cache(CacheBase):
|
|
"""Simple thread-safe DNS answer cache."""
|
|
|
|
def __init__(self, cleaning_interval=300.0):
|
|
"""*cleaning_interval*, a ``float`` is the number of seconds between
|
|
periodic cleanings.
|
|
"""
|
|
|
|
super().__init__()
|
|
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.items():
|
|
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 *key*.
|
|
|
|
Returns None if no answer is cached for the key.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
|
|
Returns a ``dns.resolver.Answer`` or ``None``.
|
|
"""
|
|
|
|
with self.lock:
|
|
self._maybe_clean()
|
|
v = self.data.get(key)
|
|
if v is None or v.expiration <= time.time():
|
|
self.statistics.misses += 1
|
|
return None
|
|
self.statistics.hits += 1
|
|
return v
|
|
|
|
def put(self, key, value):
|
|
"""Associate key and value in the cache.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
|
|
*value*, a ``dns.resolver.Answer``, the answer.
|
|
"""
|
|
|
|
with self.lock:
|
|
self._maybe_clean()
|
|
self.data[key] = value
|
|
|
|
def flush(self, key=None):
|
|
"""Flush the cache.
|
|
|
|
If *key* is not ``None``, only that item is flushed. Otherwise
|
|
the entire cache is flushed.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
"""
|
|
|
|
with self.lock:
|
|
if key is not None:
|
|
if key in self.data:
|
|
del self.data[key]
|
|
else:
|
|
self.data = {}
|
|
self.next_cleaning = time.time() + self.cleaning_interval
|
|
|
|
|
|
class LRUCacheNode:
|
|
"""LRUCache node."""
|
|
|
|
def __init__(self, key, value):
|
|
self.key = key
|
|
self.value = value
|
|
self.hits = 0
|
|
self.prev = self
|
|
self.next = self
|
|
|
|
def link_after(self, node):
|
|
self.prev = node
|
|
self.next = node.next
|
|
node.next.prev = self
|
|
node.next = self
|
|
|
|
def unlink(self):
|
|
self.next.prev = self.prev
|
|
self.prev.next = self.next
|
|
|
|
|
|
class LRUCache(CacheBase):
|
|
"""Thread-safe, bounded, least-recently-used DNS answer cache.
|
|
|
|
This cache is better than the simple cache (above) if you're
|
|
running a web crawler or other process that does a lot of
|
|
resolutions. The LRUCache has a maximum number of nodes, and when
|
|
it is full, the least-recently used node is removed to make space
|
|
for a new one.
|
|
"""
|
|
|
|
def __init__(self, max_size=100000):
|
|
"""*max_size*, an ``int``, is the maximum number of nodes to cache;
|
|
it must be greater than 0.
|
|
"""
|
|
|
|
super().__init__()
|
|
self.data = {}
|
|
self.set_max_size(max_size)
|
|
self.sentinel = LRUCacheNode(None, None)
|
|
self.sentinel.prev = self.sentinel
|
|
self.sentinel.next = self.sentinel
|
|
|
|
def set_max_size(self, max_size):
|
|
if max_size < 1:
|
|
max_size = 1
|
|
self.max_size = max_size
|
|
|
|
def get(self, key):
|
|
"""Get the answer associated with *key*.
|
|
|
|
Returns None if no answer is cached for the key.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
|
|
Returns a ``dns.resolver.Answer`` or ``None``.
|
|
"""
|
|
|
|
with self.lock:
|
|
node = self.data.get(key)
|
|
if node is None:
|
|
self.statistics.misses += 1
|
|
return None
|
|
# Unlink because we're either going to move the node to the front
|
|
# of the LRU list or we're going to free it.
|
|
node.unlink()
|
|
if node.value.expiration <= time.time():
|
|
del self.data[node.key]
|
|
self.statistics.misses += 1
|
|
return None
|
|
node.link_after(self.sentinel)
|
|
self.statistics.hits += 1
|
|
node.hits += 1
|
|
return node.value
|
|
|
|
def get_hits_for_key(self, key):
|
|
"""Return the number of cache hits associated with the specified key."""
|
|
with self.lock:
|
|
node = self.data.get(key)
|
|
if node is None or node.value.expiration <= time.time():
|
|
return 0
|
|
else:
|
|
return node.hits
|
|
|
|
def put(self, key, value):
|
|
"""Associate key and value in the cache.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
|
|
*value*, a ``dns.resolver.Answer``, the answer.
|
|
"""
|
|
|
|
with self.lock:
|
|
node = self.data.get(key)
|
|
if node is not None:
|
|
node.unlink()
|
|
del self.data[node.key]
|
|
while len(self.data) >= self.max_size:
|
|
node = self.sentinel.prev
|
|
node.unlink()
|
|
del self.data[node.key]
|
|
node = LRUCacheNode(key, value)
|
|
node.link_after(self.sentinel)
|
|
self.data[key] = node
|
|
|
|
def flush(self, key=None):
|
|
"""Flush the cache.
|
|
|
|
If *key* is not ``None``, only that item is flushed. Otherwise
|
|
the entire cache is flushed.
|
|
|
|
*key*, a ``(dns.name.Name, int, int)`` tuple whose values are the
|
|
query name, rdtype, and rdclass respectively.
|
|
"""
|
|
|
|
with self.lock:
|
|
if key is not None:
|
|
node = self.data.get(key)
|
|
if node is not None:
|
|
node.unlink()
|
|
del self.data[node.key]
|
|
else:
|
|
node = self.sentinel.next
|
|
while node != self.sentinel:
|
|
next = node.next
|
|
node.unlink()
|
|
node = next
|
|
self.data = {}
|
|
|
|
class _Resolution:
|
|
"""Helper class for dns.resolver.Resolver.resolve().
|
|
|
|
All of the "business logic" of resolution is encapsulated in this
|
|
class, allowing us to have multiple resolve() implementations
|
|
using different I/O schemes without copying all of the
|
|
complicated logic.
|
|
|
|
This class is a "friend" to dns.resolver.Resolver and manipulates
|
|
resolver data structures directly.
|
|
"""
|
|
|
|
def __init__(self, resolver, qname, rdtype, rdclass, tcp,
|
|
raise_on_no_answer, search):
|
|
if isinstance(qname, str):
|
|
qname = dns.name.from_text(qname, None)
|
|
rdtype = dns.rdatatype.RdataType.make(rdtype)
|
|
if dns.rdatatype.is_metatype(rdtype):
|
|
raise NoMetaqueries
|
|
rdclass = dns.rdataclass.RdataClass.make(rdclass)
|
|
if dns.rdataclass.is_metaclass(rdclass):
|
|
raise NoMetaqueries
|
|
self.resolver = resolver
|
|
self.qnames_to_try = resolver._get_qnames_to_try(qname, search)
|
|
self.qnames = self.qnames_to_try[:]
|
|
self.rdtype = rdtype
|
|
self.rdclass = rdclass
|
|
self.tcp = tcp
|
|
self.raise_on_no_answer = raise_on_no_answer
|
|
self.nxdomain_responses = {}
|
|
#
|
|
# Initialize other things to help analysis tools
|
|
self.qname = dns.name.empty
|
|
self.nameservers = []
|
|
self.current_nameservers = []
|
|
self.errors = []
|
|
self.nameserver = None
|
|
self.port = 0
|
|
self.tcp_attempt = False
|
|
self.retry_with_tcp = False
|
|
self.request = None
|
|
self.backoff = 0
|
|
|
|
def next_request(self):
|
|
"""Get the next request to send, and check the cache.
|
|
|
|
Returns a (request, answer) tuple. At most one of request or
|
|
answer will not be None.
|
|
"""
|
|
|
|
# We return a tuple instead of Union[Message,Answer] as it lets
|
|
# the caller avoid isinstance().
|
|
|
|
while len(self.qnames) > 0:
|
|
self.qname = self.qnames.pop(0)
|
|
|
|
# Do we know the answer?
|
|
if self.resolver.cache:
|
|
answer = self.resolver.cache.get((self.qname, self.rdtype,
|
|
self.rdclass))
|
|
if answer is not None:
|
|
if answer.rrset is None and self.raise_on_no_answer:
|
|
raise NoAnswer(response=answer.response)
|
|
else:
|
|
return (None, answer)
|
|
answer = self.resolver.cache.get((self.qname,
|
|
dns.rdatatype.ANY,
|
|
self.rdclass))
|
|
if answer is not None and \
|
|
answer.response.rcode() == dns.rcode.NXDOMAIN:
|
|
# cached NXDOMAIN; record it and continue to next
|
|
# name.
|
|
self.nxdomain_responses[self.qname] = answer.response
|
|
continue
|
|
|
|
# Build the request
|
|
request = dns.message.make_query(self.qname, self.rdtype,
|
|
self.rdclass)
|
|
if self.resolver.keyname is not None:
|
|
request.use_tsig(self.resolver.keyring, self.resolver.keyname,
|
|
algorithm=self.resolver.keyalgorithm)
|
|
request.use_edns(self.resolver.edns, self.resolver.ednsflags,
|
|
self.resolver.payload)
|
|
if self.resolver.flags is not None:
|
|
request.flags = self.resolver.flags
|
|
|
|
self.nameservers = self.resolver.nameservers[:]
|
|
if self.resolver.rotate:
|
|
random.shuffle(self.nameservers)
|
|
self.current_nameservers = self.nameservers[:]
|
|
self.errors = []
|
|
self.nameserver = None
|
|
self.tcp_attempt = False
|
|
self.retry_with_tcp = False
|
|
self.request = request
|
|
self.backoff = 0.10
|
|
|
|
return (request, None)
|
|
|
|
#
|
|
# We've tried everything and only gotten NXDOMAINs. (We know
|
|
# it's only NXDOMAINs as anything else would have returned
|
|
# before now.)
|
|
#
|
|
raise NXDOMAIN(qnames=self.qnames_to_try,
|
|
responses=self.nxdomain_responses)
|
|
|
|
def next_nameserver(self):
|
|
if self.retry_with_tcp:
|
|
assert self.nameserver is not None
|
|
self.tcp_attempt = True
|
|
self.retry_with_tcp = False
|
|
return (self.nameserver, self.port, True, 0)
|
|
|
|
backoff = 0
|
|
if not self.current_nameservers:
|
|
if len(self.nameservers) == 0:
|
|
# Out of things to try!
|
|
raise NoNameservers(request=self.request, errors=self.errors)
|
|
self.current_nameservers = self.nameservers[:]
|
|
backoff = self.backoff
|
|
self.backoff = min(self.backoff * 2, 2)
|
|
|
|
self.nameserver = self.current_nameservers.pop(0)
|
|
self.port = self.resolver.nameserver_ports.get(self.nameserver,
|
|
self.resolver.port)
|
|
self.tcp_attempt = self.tcp
|
|
return (self.nameserver, self.port, self.tcp_attempt, backoff)
|
|
|
|
def query_result(self, response, ex):
|
|
#
|
|
# returns an (answer: Answer, end_loop: bool) tuple.
|
|
#
|
|
if ex:
|
|
# Exception during I/O or from_wire()
|
|
assert response is None
|
|
self.errors.append((self.nameserver, self.tcp_attempt, self.port,
|
|
ex, response))
|
|
if isinstance(ex, dns.exception.FormError) or \
|
|
isinstance(ex, EOFError) or \
|
|
isinstance(ex, OSError) or \
|
|
isinstance(ex, NotImplementedError):
|
|
# This nameserver is no good, take it out of the mix.
|
|
self.nameservers.remove(self.nameserver)
|
|
elif isinstance(ex, dns.message.Truncated):
|
|
if self.tcp_attempt:
|
|
# Truncation with TCP is no good!
|
|
self.nameservers.remove(self.nameserver)
|
|
else:
|
|
self.retry_with_tcp = True
|
|
return (None, False)
|
|
# We got an answer!
|
|
assert response is not None
|
|
rcode = response.rcode()
|
|
if rcode == dns.rcode.NOERROR:
|
|
try:
|
|
answer = Answer(self.qname, self.rdtype, self.rdclass, response,
|
|
self.nameserver, self.port)
|
|
except Exception as e:
|
|
self.errors.append((self.nameserver, self.tcp_attempt,
|
|
self.port, e, response))
|
|
# The nameserver is no good, take it out of the mix.
|
|
self.nameservers.remove(self.nameserver)
|
|
return (None, False)
|
|
if self.resolver.cache:
|
|
self.resolver.cache.put((self.qname, self.rdtype,
|
|
self.rdclass), answer)
|
|
if answer.rrset is None and self.raise_on_no_answer:
|
|
raise NoAnswer(response=answer.response)
|
|
return (answer, True)
|
|
elif rcode == dns.rcode.NXDOMAIN:
|
|
# Further validate the response by making an Answer, even
|
|
# if we aren't going to cache it.
|
|
try:
|
|
answer = Answer(self.qname, dns.rdatatype.ANY,
|
|
dns.rdataclass.IN, response)
|
|
except Exception as e:
|
|
self.errors.append((self.nameserver, self.tcp_attempt,
|
|
self.port, e, response))
|
|
# The nameserver is no good, take it out of the mix.
|
|
self.nameservers.remove(self.nameserver)
|
|
return (None, False)
|
|
self.nxdomain_responses[self.qname] = response
|
|
if self.resolver.cache:
|
|
self.resolver.cache.put((self.qname,
|
|
dns.rdatatype.ANY,
|
|
self.rdclass), answer)
|
|
# Make next_nameserver() return None, so caller breaks its
|
|
# inner loop and calls next_request().
|
|
return (None, True)
|
|
elif rcode == dns.rcode.YXDOMAIN:
|
|
yex = YXDOMAIN()
|
|
self.errors.append((self.nameserver, self.tcp_attempt,
|
|
self.port, yex, response))
|
|
raise yex
|
|
else:
|
|
#
|
|
# We got a response, but we're not happy with the
|
|
# rcode in it.
|
|
#
|
|
if rcode != dns.rcode.SERVFAIL or not self.resolver.retry_servfail:
|
|
self.nameservers.remove(self.nameserver)
|
|
self.errors.append((self.nameserver, self.tcp_attempt, self.port,
|
|
dns.rcode.to_text(rcode), response))
|
|
return (None, False)
|
|
|
|
class BaseResolver:
|
|
"""DNS stub resolver."""
|
|
|
|
# We initialize in reset()
|
|
#
|
|
# pylint: disable=attribute-defined-outside-init
|
|
|
|
def __init__(self, filename='/etc/resolv.conf', configure=True):
|
|
"""*filename*, a ``str`` or file object, specifying a file
|
|
in standard /etc/resolv.conf format. This parameter is meaningful
|
|
only when *configure* is true and the platform is POSIX.
|
|
|
|
*configure*, a ``bool``. If True (the default), the resolver
|
|
instance is configured in the normal fashion for the operating
|
|
system the resolver is running on. (I.e. by reading a
|
|
/etc/resolv.conf file on POSIX systems and from the registry
|
|
on Windows systems.)
|
|
"""
|
|
|
|
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.nameserver_ports = {}
|
|
self.port = 53
|
|
self.search = []
|
|
self.use_search_by_default = False
|
|
self.timeout = 2.0
|
|
self.lifetime = 5.0
|
|
self.keyring = None
|
|
self.keyname = None
|
|
self.keyalgorithm = dns.tsig.default_algorithm
|
|
self.edns = -1
|
|
self.ednsflags = 0
|
|
self.payload = 0
|
|
self.cache = None
|
|
self.flags = None
|
|
self.retry_servfail = False
|
|
self.rotate = False
|
|
self.ndots = None
|
|
|
|
def read_resolv_conf(self, f):
|
|
"""Process *f* as a file in the /etc/resolv.conf format. If f is
|
|
a ``str``, it is used as the name of the file to open; otherwise it
|
|
is treated as the file itself.
|
|
|
|
Interprets the following items:
|
|
|
|
- nameserver - name server IP address
|
|
|
|
- domain - local domain name
|
|
|
|
- search - search list for host-name lookup
|
|
|
|
- options - supported options are rotate, timeout, edns0, and ndots
|
|
|
|
"""
|
|
|
|
with contextlib.ExitStack() as stack:
|
|
if isinstance(f, str):
|
|
try:
|
|
f = stack.enter_context(open(f))
|
|
except OSError:
|
|
# /etc/resolv.conf doesn't exist, can't be read, etc.
|
|
raise NoResolverConfiguration(f'cannot open {f}')
|
|
|
|
for l in f:
|
|
if len(l) == 0 or l[0] == '#' or l[0] == ';':
|
|
continue
|
|
tokens = l.split()
|
|
|
|
# Any line containing less than 2 tokens is malformed
|
|
if len(tokens) < 2:
|
|
continue
|
|
|
|
if tokens[0] == 'nameserver':
|
|
self.nameservers.append(tokens[1])
|
|
elif tokens[0] == 'domain':
|
|
self.domain = dns.name.from_text(tokens[1])
|
|
# domain and search are exclusive
|
|
self.search = []
|
|
elif tokens[0] == 'search':
|
|
# the last search wins
|
|
self.search = []
|
|
for suffix in tokens[1:]:
|
|
self.search.append(dns.name.from_text(suffix))
|
|
# We don't set domain as it is not used if
|
|
# len(self.search) > 0
|
|
elif tokens[0] == 'options':
|
|
for opt in tokens[1:]:
|
|
if opt == 'rotate':
|
|
self.rotate = True
|
|
elif opt == 'edns0':
|
|
self.use_edns()
|
|
elif 'timeout' in opt:
|
|
try:
|
|
self.timeout = int(opt.split(':')[1])
|
|
except (ValueError, IndexError):
|
|
pass
|
|
elif 'ndots' in opt:
|
|
try:
|
|
self.ndots = int(opt.split(':')[1])
|
|
except (ValueError, IndexError):
|
|
pass
|
|
if len(self.nameservers) == 0:
|
|
raise NoResolverConfiguration('no nameservers')
|
|
|
|
def read_registry(self):
|
|
"""Extract resolver configuration from the Windows registry."""
|
|
try:
|
|
info = dns.win32util.get_dns_info()
|
|
if info.domain is not None:
|
|
self.domain = info.domain
|
|
self.nameservers = info.nameservers
|
|
self.search = info.search
|
|
except AttributeError:
|
|
raise NotImplementedError
|
|
|
|
def _compute_timeout(self, start, lifetime=None, errors=None):
|
|
lifetime = self.lifetime if lifetime is None else lifetime
|
|
now = time.time()
|
|
duration = now - start
|
|
if errors is None:
|
|
errors = []
|
|
if duration < 0:
|
|
if duration < -1:
|
|
# Time going backwards is bad. Just give up.
|
|
raise LifetimeTimeout(timeout=duration, errors=errors)
|
|
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
|
|
if duration >= lifetime:
|
|
raise LifetimeTimeout(timeout=duration, errors=errors)
|
|
return min(lifetime - duration, self.timeout)
|
|
|
|
def _get_qnames_to_try(self, qname, search):
|
|
# This is a separate method so we can unit test the search
|
|
# rules without requiring the Internet.
|
|
if search is None:
|
|
search = self.use_search_by_default
|
|
qnames_to_try = []
|
|
if qname.is_absolute():
|
|
qnames_to_try.append(qname)
|
|
else:
|
|
abs_qname = qname.concatenate(dns.name.root)
|
|
if search:
|
|
if len(self.search) > 0:
|
|
# There is a search list, so use it exclusively
|
|
search_list = self.search[:]
|
|
elif self.domain != dns.name.root and self.domain is not None:
|
|
# We have some notion of a domain that isn't the root, so
|
|
# use it as the search list.
|
|
search_list = [self.domain]
|
|
else:
|
|
search_list = []
|
|
# Figure out the effective ndots (default is 1)
|
|
if self.ndots is None:
|
|
ndots = 1
|
|
else:
|
|
ndots = self.ndots
|
|
for suffix in search_list:
|
|
qnames_to_try.append(qname + suffix)
|
|
if len(qname) > ndots:
|
|
# The name has at least ndots dots, so we should try an
|
|
# absolute query first.
|
|
qnames_to_try.insert(0, abs_qname)
|
|
else:
|
|
# The name has less than ndots dots, so we should search
|
|
# first, then try the absolute name.
|
|
qnames_to_try.append(abs_qname)
|
|
else:
|
|
qnames_to_try.append(abs_qname)
|
|
return qnames_to_try
|
|
|
|
def use_tsig(self, keyring, keyname=None,
|
|
algorithm=dns.tsig.default_algorithm):
|
|
"""Add a TSIG signature to each query.
|
|
|
|
The parameters are passed to ``dns.message.Message.use_tsig()``;
|
|
see its documentation for details.
|
|
"""
|
|
|
|
self.keyring = keyring
|
|
self.keyname = keyname
|
|
self.keyalgorithm = algorithm
|
|
|
|
def use_edns(self, edns=0, ednsflags=0,
|
|
payload=dns.message.DEFAULT_EDNS_PAYLOAD):
|
|
"""Configure EDNS behavior.
|
|
|
|
*edns*, an ``int``, is the EDNS level to use. Specifying
|
|
``None``, ``False``, or ``-1`` means "do not use EDNS", and in this case
|
|
the other parameters are ignored. Specifying ``True`` is
|
|
equivalent to specifying 0, i.e. "use EDNS0".
|
|
|
|
*ednsflags*, an ``int``, the EDNS flag values.
|
|
|
|
*payload*, an ``int``, is the EDNS sender's payload field, which is the
|
|
maximum size of UDP datagram the sender can handle. I.e. how big
|
|
a response to this message can be.
|
|
"""
|
|
|
|
if edns is None or edns is False:
|
|
edns = -1
|
|
elif edns is True:
|
|
edns = 0
|
|
self.edns = edns
|
|
self.ednsflags = ednsflags
|
|
self.payload = payload
|
|
|
|
def set_flags(self, flags):
|
|
"""Overrides the default flags with your own.
|
|
|
|
*flags*, an ``int``, the message flags to use.
|
|
"""
|
|
|
|
self.flags = flags
|
|
|
|
@property
|
|
def nameservers(self):
|
|
return self._nameservers
|
|
|
|
@nameservers.setter
|
|
def nameservers(self, nameservers):
|
|
"""
|
|
*nameservers*, a ``list`` of nameservers.
|
|
|
|
Raises ``ValueError`` if *nameservers* is anything other than a
|
|
``list``.
|
|
"""
|
|
if isinstance(nameservers, list):
|
|
for nameserver in nameservers:
|
|
if not dns.inet.is_address(nameserver):
|
|
try:
|
|
if urlparse(nameserver).scheme != 'https':
|
|
raise NotImplementedError
|
|
except Exception:
|
|
raise ValueError(f'nameserver {nameserver} is not an '
|
|
'IP address or valid https URL')
|
|
self._nameservers = nameservers
|
|
else:
|
|
raise ValueError('nameservers must be a list'
|
|
' (not a {})'.format(type(nameservers)))
|
|
|
|
|
|
class Resolver(BaseResolver):
|
|
"""DNS stub resolver."""
|
|
|
|
def resolve(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
|
|
tcp=False, source=None, raise_on_no_answer=True, source_port=0,
|
|
lifetime=None, search=None): # pylint: disable=arguments-differ
|
|
"""Query nameservers to find the answer to the question.
|
|
|
|
The *qname*, *rdtype*, and *rdclass* parameters may be objects
|
|
of the appropriate type, or strings that can be converted into objects
|
|
of the appropriate type.
|
|
|
|
*qname*, a ``dns.name.Name`` or ``str``, the query name.
|
|
|
|
*rdtype*, an ``int`` or ``str``, the query type.
|
|
|
|
*rdclass*, an ``int`` or ``str``, the query class.
|
|
|
|
*tcp*, a ``bool``. If ``True``, use TCP to make the query.
|
|
|
|
*source*, a ``str`` or ``None``. If not ``None``, bind to this IP
|
|
address when making queries.
|
|
|
|
*raise_on_no_answer*, a ``bool``. If ``True``, raise
|
|
``dns.resolver.NoAnswer`` if there's no answer to the question.
|
|
|
|
*source_port*, an ``int``, the port from which to send the message.
|
|
|
|
*lifetime*, a ``float``, how many seconds a query should run
|
|
before timing out.
|
|
|
|
*search*, a ``bool`` or ``None``, determines whether the
|
|
search list configured in the system's resolver configuration
|
|
are used for relative names, and whether the resolver's domain
|
|
may be added to relative names. The default is ``None``,
|
|
which causes the value of the resolver's
|
|
``use_search_by_default`` attribute to be used.
|
|
|
|
Raises ``dns.resolver.LifetimeTimeout`` if no answers could be found
|
|
in the specified lifetime.
|
|
|
|
Raises ``dns.resolver.NXDOMAIN`` if the query name does not exist.
|
|
|
|
Raises ``dns.resolver.YXDOMAIN`` if the query name is too long after
|
|
DNAME substitution.
|
|
|
|
Raises ``dns.resolver.NoAnswer`` if *raise_on_no_answer* is
|
|
``True`` and the query name exists but has no RRset of the
|
|
desired type and class.
|
|
|
|
Raises ``dns.resolver.NoNameservers`` if no non-broken
|
|
nameservers are available to answer the question.
|
|
|
|
Returns a ``dns.resolver.Answer`` instance.
|
|
|
|
"""
|
|
|
|
resolution = _Resolution(self, qname, rdtype, rdclass, tcp,
|
|
raise_on_no_answer, search)
|
|
start = time.time()
|
|
while True:
|
|
(request, answer) = resolution.next_request()
|
|
# Note we need to say "if answer is not None" and not just
|
|
# "if answer" because answer implements __len__, and python
|
|
# will call that. We want to return if we have an answer
|
|
# object, including in cases where its length is 0.
|
|
if answer is not None:
|
|
# cache hit!
|
|
return answer
|
|
done = False
|
|
while not done:
|
|
(nameserver, port, tcp, backoff) = resolution.next_nameserver()
|
|
if backoff:
|
|
time.sleep(backoff)
|
|
timeout = self._compute_timeout(start, lifetime,
|
|
resolution.errors)
|
|
try:
|
|
if dns.inet.is_address(nameserver):
|
|
if tcp:
|
|
response = dns.query.tcp(request, nameserver,
|
|
timeout=timeout,
|
|
port=port,
|
|
source=source,
|
|
source_port=source_port)
|
|
else:
|
|
response = dns.query.udp(request,
|
|
nameserver,
|
|
timeout=timeout,
|
|
port=port,
|
|
source=source,
|
|
source_port=source_port,
|
|
raise_on_truncation=True)
|
|
else:
|
|
response = dns.query.https(request, nameserver,
|
|
timeout=timeout)
|
|
except Exception as ex:
|
|
(_, done) = resolution.query_result(None, ex)
|
|
continue
|
|
(answer, done) = resolution.query_result(response, None)
|
|
# Note we need to say "if answer is not None" and not just
|
|
# "if answer" because answer implements __len__, and python
|
|
# will call that. We want to return if we have an answer
|
|
# object, including in cases where its length is 0.
|
|
if answer is not None:
|
|
return answer
|
|
|
|
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
|
|
tcp=False, source=None, raise_on_no_answer=True, source_port=0,
|
|
lifetime=None): # pragma: no cover
|
|
"""Query nameservers to find the answer to the question.
|
|
|
|
This method calls resolve() with ``search=True``, and is
|
|
provided for backwards compatibility with prior versions of
|
|
dnspython. See the documentation for the resolve() method for
|
|
further details.
|
|
"""
|
|
warnings.warn('please use dns.resolver.Resolver.resolve() instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return self.resolve(qname, rdtype, rdclass, tcp, source,
|
|
raise_on_no_answer, source_port, lifetime,
|
|
True)
|
|
|
|
def resolve_address(self, ipaddr, *args, **kwargs):
|
|
"""Use a resolver to run a reverse query for PTR records.
|
|
|
|
This utilizes the resolve() method to perform a PTR lookup on the
|
|
specified IP address.
|
|
|
|
*ipaddr*, a ``str``, the IPv4 or IPv6 address you want to get
|
|
the PTR record for.
|
|
|
|
All other arguments that can be passed to the resolve() function
|
|
except for rdtype and rdclass are also supported by this
|
|
function.
|
|
"""
|
|
|
|
return self.resolve(dns.reversename.from_address(ipaddr),
|
|
rdtype=dns.rdatatype.PTR,
|
|
rdclass=dns.rdataclass.IN,
|
|
*args, **kwargs)
|
|
|
|
# pylint: disable=redefined-outer-name
|
|
|
|
def canonical_name(self, name):
|
|
"""Determine the canonical name of *name*.
|
|
|
|
The canonical name is the name the resolver uses for queries
|
|
after all CNAME and DNAME renamings have been applied.
|
|
|
|
*name*, a ``dns.name.Name`` or ``str``, the query name.
|
|
|
|
This method can raise any exception that ``resolve()`` can
|
|
raise, other than ``dns.resolver.NoAnswer`` and
|
|
``dns.resolver.NXDOMAIN``.
|
|
|
|
Returns a ``dns.name.Name``.
|
|
"""
|
|
try:
|
|
answer = self.resolve(name, raise_on_no_answer=False)
|
|
canonical_name = answer.canonical_name
|
|
except dns.resolver.NXDOMAIN as e:
|
|
canonical_name = e.canonical_name
|
|
return canonical_name
|
|
|
|
# pylint: enable=redefined-outer-name
|
|
|
|
|
|
#: The default resolver.
|
|
default_resolver = None
|
|
|
|
|
|
def get_default_resolver():
|
|
"""Get the default resolver, initializing it if necessary."""
|
|
if default_resolver is None:
|
|
reset_default_resolver()
|
|
return default_resolver
|
|
|
|
|
|
def reset_default_resolver():
|
|
"""Re-initialize default resolver.
|
|
|
|
Note that the resolver configuration (i.e. /etc/resolv.conf on UNIX
|
|
systems) will be re-read immediately.
|
|
"""
|
|
|
|
global default_resolver
|
|
default_resolver = Resolver()
|
|
|
|
|
|
def resolve(qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
|
|
tcp=False, source=None, raise_on_no_answer=True,
|
|
source_port=0, lifetime=None, search=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 ``dns.resolver.Resolver.resolve`` for more information on the
|
|
parameters.
|
|
"""
|
|
|
|
return get_default_resolver().resolve(qname, rdtype, rdclass, tcp, source,
|
|
raise_on_no_answer, source_port,
|
|
lifetime, search)
|
|
|
|
def query(qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
|
|
tcp=False, source=None, raise_on_no_answer=True,
|
|
source_port=0, lifetime=None): # pragma: no cover
|
|
"""Query nameservers to find the answer to the question.
|
|
|
|
This method calls resolve() with ``search=True``, and is
|
|
provided for backwards compatibility with prior versions of
|
|
dnspython. See the documentation for the resolve() method for
|
|
further details.
|
|
"""
|
|
warnings.warn('please use dns.resolver.resolve() instead',
|
|
DeprecationWarning, stacklevel=2)
|
|
return resolve(qname, rdtype, rdclass, tcp, source,
|
|
raise_on_no_answer, source_port, lifetime,
|
|
True)
|
|
|
|
|
|
def resolve_address(ipaddr, *args, **kwargs):
|
|
"""Use a resolver to run a reverse query for PTR records.
|
|
|
|
See ``dns.resolver.Resolver.resolve_address`` for more information on the
|
|
parameters.
|
|
"""
|
|
|
|
return get_default_resolver().resolve_address(ipaddr, *args, **kwargs)
|
|
|
|
|
|
def canonical_name(name):
|
|
"""Determine the canonical name of *name*.
|
|
|
|
See ``dns.resolver.Resolver.canonical_name`` for more information on the
|
|
parameters and possible exceptions.
|
|
"""
|
|
|
|
return get_default_resolver().canonical_name(name)
|
|
|
|
|
|
def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None,
|
|
lifetime=None):
|
|
"""Find the name of the zone which contains the specified name.
|
|
|
|
*name*, an absolute ``dns.name.Name`` or ``str``, the query name.
|
|
|
|
*rdclass*, an ``int``, the query class.
|
|
|
|
*tcp*, a ``bool``. If ``True``, use TCP to make the query.
|
|
|
|
*resolver*, a ``dns.resolver.Resolver`` or ``None``, the resolver to use.
|
|
If ``None``, the default, then the default resolver is used.
|
|
|
|
*lifetime*, a ``float``, the total time to allow for the queries needed
|
|
to determine the zone. If ``None``, the default, then only the individual
|
|
query limits of the resolver apply.
|
|
|
|
Raises ``dns.resolver.NoRootSOA`` if there is no SOA RR at the DNS
|
|
root. (This is only likely to happen if you're using non-default
|
|
root servers in your network and they are misconfigured.)
|
|
|
|
Raises ``dns.resolver.LifetimeTimeout`` if the answer could not be
|
|
found in the allotted lifetime.
|
|
|
|
Returns a ``dns.name.Name``.
|
|
"""
|
|
|
|
if isinstance(name, str):
|
|
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)
|
|
start = time.time()
|
|
if lifetime is not None:
|
|
expiration = start + lifetime
|
|
else:
|
|
expiration = None
|
|
while 1:
|
|
try:
|
|
if expiration:
|
|
rlifetime = expiration - time.time()
|
|
if rlifetime <= 0:
|
|
rlifetime = 0
|
|
else:
|
|
rlifetime = None
|
|
answer = resolver.resolve(name, dns.rdatatype.SOA, rdclass, tcp,
|
|
lifetime=rlifetime)
|
|
if answer.rrset.name == name:
|
|
return name
|
|
# otherwise we were CNAMEd or DNAMEd and need to look higher
|
|
except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer) as e:
|
|
if isinstance(e, dns.resolver.NXDOMAIN):
|
|
response = e.responses().get(name)
|
|
else:
|
|
response = e.response() # pylint: disable=no-value-for-parameter
|
|
if response:
|
|
for rrs in response.authority:
|
|
if rrs.rdtype == dns.rdatatype.SOA and \
|
|
rrs.rdclass == rdclass:
|
|
(nr, _, _) = rrs.name.fullcompare(name)
|
|
if nr == dns.name.NAMERELN_SUPERDOMAIN:
|
|
# We're doing a proper superdomain check as
|
|
# if the name were equal we ought to have gotten
|
|
# it in the answer section! We are ignoring the
|
|
# possibility that the authority is insane and
|
|
# is including multiple SOA RRs for different
|
|
# authorities.
|
|
return rrs.name
|
|
# we couldn't extract anything useful from the response (e.g. it's
|
|
# a type 3 NXDOMAIN)
|
|
try:
|
|
name = name.parent()
|
|
except dns.name.NoParent:
|
|
raise NoRootSOA
|
|
|
|
#
|
|
# Support for overriding the system resolver for all python code in the
|
|
# running process.
|
|
#
|
|
|
|
_protocols_for_socktype = {
|
|
socket.SOCK_DGRAM: [socket.SOL_UDP],
|
|
socket.SOCK_STREAM: [socket.SOL_TCP],
|
|
}
|
|
|
|
_resolver = None
|
|
_original_getaddrinfo = socket.getaddrinfo
|
|
_original_getnameinfo = socket.getnameinfo
|
|
_original_getfqdn = socket.getfqdn
|
|
_original_gethostbyname = socket.gethostbyname
|
|
_original_gethostbyname_ex = socket.gethostbyname_ex
|
|
_original_gethostbyaddr = socket.gethostbyaddr
|
|
|
|
|
|
def _getaddrinfo(host=None, service=None, family=socket.AF_UNSPEC, socktype=0,
|
|
proto=0, flags=0):
|
|
if flags & socket.AI_NUMERICHOST != 0:
|
|
# Short circuit directly into the system's getaddrinfo(). We're
|
|
# not adding any value in this case, and this avoids infinite loops
|
|
# because dns.query.* needs to call getaddrinfo() for IPv6 scoping
|
|
# reasons. We will also do this short circuit below if we
|
|
# discover that the host is an address literal.
|
|
return _original_getaddrinfo(host, service, family, socktype, proto,
|
|
flags)
|
|
if flags & (socket.AI_ADDRCONFIG | socket.AI_V4MAPPED) != 0:
|
|
# Not implemented. We raise a gaierror as opposed to a
|
|
# NotImplementedError as it helps callers handle errors more
|
|
# appropriately. [Issue #316]
|
|
#
|
|
# We raise EAI_FAIL as opposed to EAI_SYSTEM because there is
|
|
# no EAI_SYSTEM on Windows [Issue #416]. We didn't go for
|
|
# EAI_BADFLAGS as the flags aren't bad, we just don't
|
|
# implement them.
|
|
raise socket.gaierror(socket.EAI_FAIL,
|
|
'Non-recoverable failure in name resolution')
|
|
if host is None and service is None:
|
|
raise socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
|
|
v6addrs = []
|
|
v4addrs = []
|
|
canonical_name = None # pylint: disable=redefined-outer-name
|
|
# Is host None or an address literal? If so, use the system's
|
|
# getaddrinfo().
|
|
if host is None:
|
|
return _original_getaddrinfo(host, service, family, socktype,
|
|
proto, flags)
|
|
try:
|
|
# We don't care about the result of af_for_address(), we're just
|
|
# calling it so it raises an exception if host is not an IPv4 or
|
|
# IPv6 address.
|
|
dns.inet.af_for_address(host)
|
|
return _original_getaddrinfo(host, service, family, socktype,
|
|
proto, flags)
|
|
except Exception:
|
|
pass
|
|
# Something needs resolution!
|
|
try:
|
|
if family == socket.AF_INET6 or family == socket.AF_UNSPEC:
|
|
v6 = _resolver.resolve(host, dns.rdatatype.AAAA,
|
|
raise_on_no_answer=False)
|
|
# Note that setting host ensures we query the same name
|
|
# for A as we did for AAAA.
|
|
host = v6.qname
|
|
canonical_name = v6.canonical_name.to_text(True)
|
|
if v6.rrset is not None:
|
|
for rdata in v6.rrset:
|
|
v6addrs.append(rdata.address)
|
|
if family == socket.AF_INET or family == socket.AF_UNSPEC:
|
|
v4 = _resolver.resolve(host, dns.rdatatype.A,
|
|
raise_on_no_answer=False)
|
|
host = v4.qname
|
|
canonical_name = v4.canonical_name.to_text(True)
|
|
if v4.rrset is not None:
|
|
for rdata in v4.rrset:
|
|
v4addrs.append(rdata.address)
|
|
except dns.resolver.NXDOMAIN:
|
|
raise socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
|
|
except Exception:
|
|
# We raise EAI_AGAIN here as the failure may be temporary
|
|
# (e.g. a timeout) and EAI_SYSTEM isn't defined on Windows.
|
|
# [Issue #416]
|
|
raise socket.gaierror(socket.EAI_AGAIN,
|
|
'Temporary failure in name resolution')
|
|
port = None
|
|
try:
|
|
# Is it a port literal?
|
|
if service is None:
|
|
port = 0
|
|
else:
|
|
port = int(service)
|
|
except Exception:
|
|
if flags & socket.AI_NUMERICSERV == 0:
|
|
try:
|
|
port = socket.getservbyname(service)
|
|
except Exception:
|
|
pass
|
|
if port is None:
|
|
raise socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
|
|
tuples = []
|
|
if socktype == 0:
|
|
socktypes = [socket.SOCK_DGRAM, socket.SOCK_STREAM]
|
|
else:
|
|
socktypes = [socktype]
|
|
if flags & socket.AI_CANONNAME != 0:
|
|
cname = canonical_name
|
|
else:
|
|
cname = ''
|
|
if family == socket.AF_INET6 or family == socket.AF_UNSPEC:
|
|
for addr in v6addrs:
|
|
for socktype in socktypes:
|
|
for proto in _protocols_for_socktype[socktype]:
|
|
tuples.append((socket.AF_INET6, socktype, proto,
|
|
cname, (addr, port, 0, 0)))
|
|
if family == socket.AF_INET or family == socket.AF_UNSPEC:
|
|
for addr in v4addrs:
|
|
for socktype in socktypes:
|
|
for proto in _protocols_for_socktype[socktype]:
|
|
tuples.append((socket.AF_INET, socktype, proto,
|
|
cname, (addr, port)))
|
|
if len(tuples) == 0:
|
|
raise socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
|
|
return tuples
|
|
|
|
|
|
def _getnameinfo(sockaddr, flags=0):
|
|
host = sockaddr[0]
|
|
port = sockaddr[1]
|
|
if len(sockaddr) == 4:
|
|
scope = sockaddr[3]
|
|
family = socket.AF_INET6
|
|
else:
|
|
scope = None
|
|
family = socket.AF_INET
|
|
tuples = _getaddrinfo(host, port, family, socket.SOCK_STREAM,
|
|
socket.SOL_TCP, 0)
|
|
if len(tuples) > 1:
|
|
raise socket.error('sockaddr resolved to multiple addresses')
|
|
addr = tuples[0][4][0]
|
|
if flags & socket.NI_DGRAM:
|
|
pname = 'udp'
|
|
else:
|
|
pname = 'tcp'
|
|
qname = dns.reversename.from_address(addr)
|
|
if flags & socket.NI_NUMERICHOST == 0:
|
|
try:
|
|
answer = _resolver.resolve(qname, 'PTR')
|
|
hostname = answer.rrset[0].target.to_text(True)
|
|
except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
|
|
if flags & socket.NI_NAMEREQD:
|
|
raise socket.gaierror(socket.EAI_NONAME,
|
|
'Name or service not known')
|
|
hostname = addr
|
|
if scope is not None:
|
|
hostname += '%' + str(scope)
|
|
else:
|
|
hostname = addr
|
|
if scope is not None:
|
|
hostname += '%' + str(scope)
|
|
if flags & socket.NI_NUMERICSERV:
|
|
service = str(port)
|
|
else:
|
|
service = socket.getservbyport(port, pname)
|
|
return (hostname, service)
|
|
|
|
|
|
def _getfqdn(name=None):
|
|
if name is None:
|
|
name = socket.gethostname()
|
|
try:
|
|
(name, _, _) = _gethostbyaddr(name)
|
|
# Python's version checks aliases too, but our gethostbyname
|
|
# ignores them, so we do so here as well.
|
|
except Exception:
|
|
pass
|
|
return name
|
|
|
|
|
|
def _gethostbyname(name):
|
|
return _gethostbyname_ex(name)[2][0]
|
|
|
|
|
|
def _gethostbyname_ex(name):
|
|
aliases = []
|
|
addresses = []
|
|
tuples = _getaddrinfo(name, 0, socket.AF_INET, socket.SOCK_STREAM,
|
|
socket.SOL_TCP, socket.AI_CANONNAME)
|
|
canonical = tuples[0][3]
|
|
for item in tuples:
|
|
addresses.append(item[4][0])
|
|
# XXX we just ignore aliases
|
|
return (canonical, aliases, addresses)
|
|
|
|
|
|
def _gethostbyaddr(ip):
|
|
try:
|
|
dns.ipv6.inet_aton(ip)
|
|
sockaddr = (ip, 80, 0, 0)
|
|
family = socket.AF_INET6
|
|
except Exception:
|
|
try:
|
|
dns.ipv4.inet_aton(ip)
|
|
except Exception:
|
|
raise socket.gaierror(socket.EAI_NONAME,
|
|
'Name or service not known')
|
|
sockaddr = (ip, 80)
|
|
family = socket.AF_INET
|
|
(name, _) = _getnameinfo(sockaddr, socket.NI_NAMEREQD)
|
|
aliases = []
|
|
addresses = []
|
|
tuples = _getaddrinfo(name, 0, family, socket.SOCK_STREAM, socket.SOL_TCP,
|
|
socket.AI_CANONNAME)
|
|
canonical = tuples[0][3]
|
|
# We only want to include an address from the tuples if it's the
|
|
# same as the one we asked about. We do this comparison in binary
|
|
# to avoid any differences in text representations.
|
|
bin_ip = dns.inet.inet_pton(family, ip)
|
|
for item in tuples:
|
|
addr = item[4][0]
|
|
bin_addr = dns.inet.inet_pton(family, addr)
|
|
if bin_ip == bin_addr:
|
|
addresses.append(addr)
|
|
# XXX we just ignore aliases
|
|
return (canonical, aliases, addresses)
|
|
|
|
|
|
def override_system_resolver(resolver=None):
|
|
"""Override the system resolver routines in the socket module with
|
|
versions which use dnspython's resolver.
|
|
|
|
This can be useful in testing situations where you want to control
|
|
the resolution behavior of python code without having to change
|
|
the system's resolver settings (e.g. /etc/resolv.conf).
|
|
|
|
The resolver to use may be specified; if it's not, the default
|
|
resolver will be used.
|
|
|
|
resolver, a ``dns.resolver.Resolver`` or ``None``, the resolver to use.
|
|
"""
|
|
|
|
if resolver is None:
|
|
resolver = get_default_resolver()
|
|
global _resolver
|
|
_resolver = resolver
|
|
socket.getaddrinfo = _getaddrinfo
|
|
socket.getnameinfo = _getnameinfo
|
|
socket.getfqdn = _getfqdn
|
|
socket.gethostbyname = _gethostbyname
|
|
socket.gethostbyname_ex = _gethostbyname_ex
|
|
socket.gethostbyaddr = _gethostbyaddr
|
|
|
|
|
|
def restore_system_resolver():
|
|
"""Undo the effects of prior override_system_resolver()."""
|
|
|
|
global _resolver
|
|
_resolver = None
|
|
socket.getaddrinfo = _original_getaddrinfo
|
|
socket.getnameinfo = _original_getnameinfo
|
|
socket.getfqdn = _original_getfqdn
|
|
socket.gethostbyname = _original_gethostbyname
|
|
socket.gethostbyname_ex = _original_gethostbyname_ex
|
|
socket.gethostbyaddr = _original_gethostbyaddr
|