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Bring back use of dnspython for A/AAAA resolution.

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This is behind a use_dnspython flag, however, so it can be disabled as
desired.
This commit is contained in:
Lance Stout 2014-06-08 19:51:57 -07:00
parent 02f79fc94b
commit ad91a8cd5e
2 changed files with 90 additions and 27 deletions
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109
sleekxmpp/xmlstream/resolver.py
View File

@ -32,10 +32,10 @@ log = logging.getLogger(__name__)
#: cd dnspython #: cd dnspython
#: git checkout python3 #: git checkout python3
#: python3 setup.py install #: python3 setup.py install
USE_DNSPYTHON = False DNSPYTHON_AVAILABLE = False
try: try:
import dns.resolver import dns.resolver
USE_DNSPYTHON = True DNSPYTHON_AVAILABLE = True
except ImportError as e: except ImportError as e:
log.debug("Could not find dnspython package. " + \ log.debug("Could not find dnspython package. " + \
"Not all features will be available") "Not all features will be available")
@ -47,13 +47,13 @@ def default_resolver():
:returns: A :class:`dns.resolver.Resolver` object if dnspython :returns: A :class:`dns.resolver.Resolver` object if dnspython
is available. Otherwise, ``None``. is available. Otherwise, ``None``.
""" """
if USE_DNSPYTHON: if DNSPYTHON_AVAILABLE:
return dns.resolver.get_default_resolver() return dns.resolver.get_default_resolver()
return None return None
def resolve(host, port=None, service=None, proto='tcp', def resolve(host, port=None, service=None, proto='tcp',
resolver=None, use_ipv6=True): resolver=None, use_ipv6=True, use_dnspython=True):
"""Peform DNS resolution for a given hostname. """Peform DNS resolution for a given hostname.
Resolution may perform SRV record lookups if a service and protocol Resolution may perform SRV record lookups if a service and protocol
@ -77,6 +77,9 @@ def resolve(host, port=None, service=None, proto='tcp',
:param use_ipv6: Optionally control the use of IPv6 in situations :param use_ipv6: Optionally control the use of IPv6 in situations
where it is either not available, or performance where it is either not available, or performance
is degraded. Defaults to ``True``. is degraded. Defaults to ``True``.
:param use_dnspython: Optionally control if dnspython is used to make
the DNS queries instead of the built-in DNS
library.
:type host: string :type host: string
:type port: int :type port: int
@ -84,14 +87,22 @@ def resolve(host, port=None, service=None, proto='tcp',
:type proto: string :type proto: string
:type resolver: :class:`dns.resolver.Resolver` :type resolver: :class:`dns.resolver.Resolver`
:type use_ipv6: bool :type use_ipv6: bool
:type use_dnspython: bool
:return: An iterable of IP address, port pairs in the order :return: An iterable of IP address, port pairs in the order
dictated by SRV priorities and weights, if applicable. dictated by SRV priorities and weights, if applicable.
""" """
if not use_dnspython:
if DNSPYTHON_AVAILABLE:
log.debug("DNS: Not using dnspython, but dnspython is installed.")
else:
log.debug("DNS: Not using dnspython.")
if not use_ipv6: if not use_ipv6:
log.debug("DNS: Use of IPv6 has been disabled.") log.debug("DNS: Use of IPv6 has been disabled.")
if resolver is None and USE_DNSPYTHON: if resolver is None and DNSPYTHON_AVAILABLE and use_dnspython:
resolver = dns.resolver.get_default_resolver() resolver = dns.resolver.get_default_resolver()
# An IPv6 literal is allowed to be enclosed in square brackets, but # An IPv6 literal is allowed to be enclosed in square brackets, but
@ -122,7 +133,9 @@ def resolve(host, port=None, service=None, proto='tcp',
if not service: if not service:
hosts = [(host, port)] hosts = [(host, port)]
else: else:
hosts = get_SRV(host, port, service, proto, resolver=resolver) hosts = get_SRV(host, port, service, proto,
resolver=resolver,
use_dnspython=use_dnspython)
for host, port in hosts: for host, port in hosts:
results = [] results = []
@ -131,16 +144,18 @@ def resolve(host, port=None, service=None, proto='tcp',
results.append((host, '::1', port)) results.append((host, '::1', port))
results.append((host, '127.0.0.1', port)) results.append((host, '127.0.0.1', port))
if use_ipv6: if use_ipv6:
for address in get_AAAA(host): for address in get_AAAA(host, resolver=resolver,
use_dnspython=use_dnspython):
results.append((host, address, port)) results.append((host, address, port))
for address in get_A(host): for address in get_A(host, resolver=resolver,
use_dnspython=use_dnspython):
results.append((host, address, port)) results.append((host, address, port))
for host, address, port in results: for host, address, port in results:
yield host, address, port yield host, address, port
def get_A(host): def get_A(host, resolver=None, use_dnspython=True):
"""Lookup DNS A records for a given host. """Lookup DNS A records for a given host.
If ``resolver`` is not provided, or is ``None``, then resolution will If ``resolver`` is not provided, or is ``None``, then resolution will
@ -148,9 +163,13 @@ def get_A(host):
:param host: The hostname to resolve for A record IPv4 addresses. :param host: The hostname to resolve for A record IPv4 addresses.
:param resolver: Optional DNS resolver object to use for the query. :param resolver: Optional DNS resolver object to use for the query.
:param use_dnspython: Optionally control if dnspython is used to make
the DNS queries instead of the built-in DNS
library.
:type host: string :type host: string
:type resolver: :class:`dns.resolver.Resolver` or ``None`` :type resolver: :class:`dns.resolver.Resolver` or ``None``
:type use_dnspython: bool
:return: A list of IPv4 literals. :return: A list of IPv4 literals.
""" """
@ -158,15 +177,32 @@ def get_A(host):
# If not using dnspython, attempt lookup using the OS level # If not using dnspython, attempt lookup using the OS level
# getaddrinfo() method. # getaddrinfo() method.
if resolver is None or not use_dnspython:
try:
recs = socket.getaddrinfo(host, None, socket.AF_INET,
socket.SOCK_STREAM)
return [rec[4][0] for rec in recs]
except socket.gaierror:
log.debug("DNS: Error retreiving A address info for %s." % host)
return []
# Using dnspython:
try: try:
recs = socket.getaddrinfo(host, None, socket.AF_INET, recs = resolver.query(host, dns.rdatatype.A)
socket.SOCK_STREAM) return [rec.to_text() for rec in recs]
return [rec[4][0] for rec in recs] except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
except socket.gaierror: log.debug("DNS: No A records for %s" % host)
log.debug("DNS: Error retreiving A address info for %s." % host) return []
except dns.exception.Timeout:
log.debug("DNS: A record resolution timed out for %s" % host)
return []
except dns.exception.DNSException as e:
log.debug("DNS: Error querying A records for %s" % host)
log.exception(e)
return [] return []
def get_AAAA(host):
def get_AAAA(host, resolver=None, use_dnspython=True):
"""Lookup DNS AAAA records for a given host. """Lookup DNS AAAA records for a given host.
If ``resolver`` is not provided, or is ``None``, then resolution will If ``resolver`` is not provided, or is ``None``, then resolution will
@ -174,9 +210,13 @@ def get_AAAA(host):
:param host: The hostname to resolve for AAAA record IPv6 addresses. :param host: The hostname to resolve for AAAA record IPv6 addresses.
:param resolver: Optional DNS resolver object to use for the query. :param resolver: Optional DNS resolver object to use for the query.
:param use_dnspython: Optionally control if dnspython is used to make
the DNS queries instead of the built-in DNS
library.
:type host: string :type host: string
:type resolver: :class:`dns.resolver.Resolver` or ``None`` :type resolver: :class:`dns.resolver.Resolver` or ``None``
:type use_dnspython: bool
:return: A list of IPv6 literals. :return: A list of IPv6 literals.
""" """
@ -184,19 +224,36 @@ def get_AAAA(host):
# If not using dnspython, attempt lookup using the OS level # If not using dnspython, attempt lookup using the OS level
# getaddrinfo() method. # getaddrinfo() method.
if not socket.has_ipv6: if resolver is None or not use_dnspython:
log.debug("Unable to query %s for AAAA records: IPv6 is not supported", host) if not socket.has_ipv6:
return [] log.debug("Unable to query %s for AAAA records: IPv6 is not supported", host)
return []
try:
recs = socket.getaddrinfo(host, None, socket.AF_INET6,
socket.SOCK_STREAM)
return [rec[4][0] for rec in recs]
except (OSError, socket.gaierror):
log.debug("DNS: Error retreiving AAAA address " + \
"info for %s." % host)
return []
# Using dnspython:
try: try:
recs = socket.getaddrinfo(host, None, socket.AF_INET6, recs = resolver.query(host, dns.rdatatype.AAAA)
socket.SOCK_STREAM) return [rec.to_text() for rec in recs]
return [rec[4][0] for rec in recs] except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
except (OSError, socket.gaierror): log.debug("DNS: No AAAA records for %s" % host)
log.debug("DNS: Error retreiving AAAA address " + \ return []
"info for %s." % host) except dns.exception.Timeout:
log.debug("DNS: AAAA record resolution timed out for %s" % host)
return []
except dns.exception.DNSException as e:
log.debug("DNS: Error querying AAAA records for %s" % host)
log.exception(e)
return [] return []
def get_SRV(host, port, service, proto='tcp', resolver=None):
def get_SRV(host, port, service, proto='tcp', resolver=None, use_dnspython=True):
"""Perform SRV record resolution for a given host. """Perform SRV record resolution for a given host.
.. note:: .. note::
@ -222,7 +279,7 @@ def get_SRV(host, port, service, proto='tcp', resolver=None):
:return: A list of hostname, port pairs in the order dictacted :return: A list of hostname, port pairs in the order dictacted
by SRV priorities and weights. by SRV priorities and weights.
""" """
if resolver is None: if resolver is None or not use_dnspython:
log.warning("DNS: dnspython not found. Can not use SRV lookup.") log.warning("DNS: dnspython not found. Can not use SRV lookup.")
return [(host, port)] return [(host, port)]

8
sleekxmpp/xmlstream/xmlstream.py
View File

@ -224,6 +224,11 @@ class XMLStream(object):
#: If set to ``True``, attempt to use IPv6. #: If set to ``True``, attempt to use IPv6.
self.use_ipv6 = True self.use_ipv6 = True
#: If set to ``True``, allow using the ``dnspython`` DNS library
#: if available. If set to ``False``, the builtin DNS resolver
#: will be used, even if ``dnspython`` is installed.
self.use_dnspython = True
#: Use CDATA for escaping instead of XML entities. Defaults #: Use CDATA for escaping instead of XML entities. Defaults
#: to ``False``. #: to ``False``.
self.use_cdata = False self.use_cdata = False
@ -1081,7 +1086,8 @@ class XMLStream(object):
return resolve(domain, port, service=self.dns_service, return resolve(domain, port, service=self.dns_service,
resolver=resolver, resolver=resolver,
use_ipv6=self.use_ipv6) use_ipv6=self.use_ipv6,
use_dnspython=self.use_dnspython)
def pick_dns_answer(self, domain, port=None): def pick_dns_answer(self, domain, port=None):
"""Pick a server and port from DNS answers. """Pick a server and port from DNS answers.