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Your IP : 216.73.216.117
'''greendns - non-blocking DNS support for Eventlet
'''
# Portions of this code taken from the gogreen project:
# http://github.com/slideinc/gogreen
#
# Copyright (c) 2005-2010 Slide, Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
# * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
# * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following
# disclaimer in the documentation and/or other materials provided
# with the distribution.
# * Neither the name of the author nor the names of other
# contributors may be used to endorse or promote products derived
# from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
import re
import struct
import sys
import eventlet
from eventlet import patcher
from eventlet.green import _socket_nodns
from eventlet.green import os
from eventlet.green import time
from eventlet.green import select
from eventlet.green import ssl
import six
def import_patched(module_name):
# Import cycle note: it's crucial to use _socket_nodns here because
# regular evenlet.green.socket imports *this* module and if we imported
# it back we'd end with an import cycle (socket -> greendns -> socket).
# We break this import cycle by providing a restricted socket module.
modules = {
'select': select,
'time': time,
'os': os,
'socket': _socket_nodns,
'ssl': ssl,
}
return patcher.import_patched(module_name, **modules)
dns = import_patched('dns')
# Handle rdtypes separately; we need fully it available as we patch the rest
dns.rdtypes = import_patched('dns.rdtypes')
dns.rdtypes.__all__.extend(['dnskeybase', 'dsbase', 'txtbase'])
for pkg in dns.rdtypes.__all__:
setattr(dns.rdtypes, pkg, import_patched('dns.rdtypes.' + pkg))
for pkg in dns.rdtypes.IN.__all__:
setattr(dns.rdtypes.IN, pkg, import_patched('dns.rdtypes.IN.' + pkg))
for pkg in dns.rdtypes.ANY.__all__:
setattr(dns.rdtypes.ANY, pkg, import_patched('dns.rdtypes.ANY.' + pkg))
for pkg in dns.__all__:
if pkg == 'rdtypes':
continue
setattr(dns, pkg, import_patched('dns.' + pkg))
del import_patched
socket = _socket_nodns
DNS_QUERY_TIMEOUT = 10.0
HOSTS_TTL = 10.0
# NOTE(victor): do not use EAI_*_ERROR instances for raising errors in python3, which will cause a memory leak.
EAI_EAGAIN_ERROR = socket.gaierror(socket.EAI_AGAIN, 'Lookup timed out')
EAI_NONAME_ERROR = socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
# EAI_NODATA was removed from RFC3493, it's now replaced with EAI_NONAME
# socket.EAI_NODATA is not defined on FreeBSD, probably on some other platforms too.
# https://lists.freebsd.org/pipermail/freebsd-ports/2003-October/005757.html
EAI_NODATA_ERROR = EAI_NONAME_ERROR
if (os.environ.get('EVENTLET_DEPRECATED_EAI_NODATA', '').lower() in ('1', 'y', 'yes')
and hasattr(socket, 'EAI_NODATA')):
EAI_NODATA_ERROR = socket.gaierror(socket.EAI_NODATA, 'No address associated with hostname')
def _raise_new_error(error_instance):
raise error_instance.__class__(*error_instance.args)
def is_ipv4_addr(host):
"""Return True if host is a valid IPv4 address"""
if not isinstance(host, six.string_types):
return False
try:
dns.ipv4.inet_aton(host)
except dns.exception.SyntaxError:
return False
else:
return True
def is_ipv6_addr(host):
"""Return True if host is a valid IPv6 address"""
if not isinstance(host, six.string_types):
return False
host = host.split('%', 1)[0]
try:
dns.ipv6.inet_aton(host)
except dns.exception.SyntaxError:
return False
else:
return True
def is_ip_addr(host):
"""Return True if host is a valid IPv4 or IPv6 address"""
return is_ipv4_addr(host) or is_ipv6_addr(host)
# NOTE(ralonsoh): in dnspython v2.0.0, "_compute_expiration" was replaced
# by "_compute_times".
if hasattr(dns.query, '_compute_expiration'):
def compute_expiration(query, timeout):
return query._compute_expiration(timeout)
else:
def compute_expiration(query, timeout):
return query._compute_times(timeout)[1]
class HostsAnswer(dns.resolver.Answer):
"""Answer class for HostsResolver object"""
def __init__(self, qname, rdtype, rdclass, rrset, raise_on_no_answer=True):
"""Create a new answer
:qname: A dns.name.Name instance of the query name
:rdtype: The rdatatype of the query
:rdclass: The rdataclass of the query
:rrset: The dns.rrset.RRset with the response, must have ttl attribute
:raise_on_no_answer: Whether to raise dns.resolver.NoAnswer if no
answer.
"""
self.response = None
self.qname = qname
self.rdtype = rdtype
self.rdclass = rdclass
self.canonical_name = qname
if not rrset and raise_on_no_answer:
raise dns.resolver.NoAnswer()
self.rrset = rrset
self.expiration = (time.time() +
rrset.ttl if hasattr(rrset, 'ttl') else 0)
class HostsResolver(object):
"""Class to parse the hosts file
Attributes
----------
:fname: The filename of the hosts file in use.
:interval: The time between checking for hosts file modification
"""
LINES_RE = re.compile(r"""
\s* # Leading space
([^\r\n#]*?) # The actual match, non-greedy so as not to include trailing space
\s* # Trailing space
(?:[#][^\r\n]+)? # Comments
(?:$|[\r\n]+) # EOF or newline
""", re.VERBOSE)
def __init__(self, fname=None, interval=HOSTS_TTL):
self._v4 = {} # name -> ipv4
self._v6 = {} # name -> ipv6
self._aliases = {} # name -> canonical_name
self.interval = interval
self.fname = fname
if fname is None:
if os.name == 'posix':
self.fname = '/etc/hosts'
elif os.name == 'nt':
self.fname = os.path.expandvars(
r'%SystemRoot%\system32\drivers\etc\hosts')
self._last_load = 0
if self.fname:
self._load()
def _readlines(self):
"""Read the contents of the hosts file
Return list of lines, comment lines and empty lines are
excluded.
Note that this performs disk I/O so can be blocking.
"""
try:
with open(self.fname, 'rb') as fp:
fdata = fp.read()
except (IOError, OSError):
return []
udata = fdata.decode(errors='ignore')
return six.moves.filter(None, self.LINES_RE.findall(udata))
def _load(self):
"""Load hosts file
This will unconditionally (re)load the data from the hosts
file.
"""
lines = self._readlines()
self._v4.clear()
self._v6.clear()
self._aliases.clear()
for line in lines:
parts = line.split()
if len(parts) < 2:
continue
ip = parts.pop(0)
if is_ipv4_addr(ip):
ipmap = self._v4
elif is_ipv6_addr(ip):
if ip.startswith('fe80'):
# Do not use link-local addresses, OSX stores these here
continue
ipmap = self._v6
else:
continue
cname = parts.pop(0).lower()
ipmap[cname] = ip
for alias in parts:
alias = alias.lower()
ipmap[alias] = ip
self._aliases[alias] = cname
self._last_load = time.time()
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True):
"""Query the hosts file
The known rdtypes are dns.rdatatype.A, dns.rdatatype.AAAA and
dns.rdatatype.CNAME.
The ``rdclass`` parameter must be dns.rdataclass.IN while the
``tcp`` and ``source`` parameters are ignored.
Return a HostAnswer instance or raise a dns.resolver.NoAnswer
exception.
"""
now = time.time()
if self._last_load + self.interval < now:
self._load()
rdclass = dns.rdataclass.IN
if isinstance(qname, six.string_types):
name = qname
qname = dns.name.from_text(qname)
elif isinstance(qname, six.binary_type):
name = qname.decode("ascii")
qname = dns.name.from_text(qname)
else:
name = str(qname)
name = name.lower()
rrset = dns.rrset.RRset(qname, rdclass, rdtype)
rrset.ttl = self._last_load + self.interval - now
if rdclass == dns.rdataclass.IN and rdtype == dns.rdatatype.A:
addr = self._v4.get(name)
if not addr and qname.is_absolute():
addr = self._v4.get(name[:-1])
if addr:
rrset.add(dns.rdtypes.IN.A.A(rdclass, rdtype, addr))
elif rdclass == dns.rdataclass.IN and rdtype == dns.rdatatype.AAAA:
addr = self._v6.get(name)
if not addr and qname.is_absolute():
addr = self._v6.get(name[:-1])
if addr:
rrset.add(dns.rdtypes.IN.AAAA.AAAA(rdclass, rdtype, addr))
elif rdclass == dns.rdataclass.IN and rdtype == dns.rdatatype.CNAME:
cname = self._aliases.get(name)
if not cname and qname.is_absolute():
cname = self._aliases.get(name[:-1])
if cname:
rrset.add(dns.rdtypes.ANY.CNAME.CNAME(
rdclass, rdtype, dns.name.from_text(cname)))
return HostsAnswer(qname, rdtype, rdclass, rrset, raise_on_no_answer)
def getaliases(self, hostname):
"""Return a list of all the aliases of a given cname"""
# Due to the way store aliases this is a bit inefficient, this
# clearly was an afterthought. But this is only used by
# gethostbyname_ex so it's probably fine.
aliases = []
if hostname in self._aliases:
cannon = self._aliases[hostname]
else:
cannon = hostname
aliases.append(cannon)
for alias, cname in six.iteritems(self._aliases):
if cannon == cname:
aliases.append(alias)
aliases.remove(hostname)
return aliases
class ResolverProxy(object):
"""Resolver class which can also use /etc/hosts
Initialise with a HostsResolver instance in order for it to also
use the hosts file.
"""
def __init__(self, hosts_resolver=None, filename='/etc/resolv.conf'):
"""Initialise the resolver proxy
:param hosts_resolver: An instance of HostsResolver to use.
:param filename: The filename containing the resolver
configuration. The default value is correct for both UNIX
and Windows, on Windows it will result in the configuration
being read from the Windows registry.
"""
self._hosts = hosts_resolver
self._filename = filename
# NOTE(dtantsur): we cannot create a resolver here since this code is
# executed on eventlet import. In an environment without DNS, creating
# a Resolver will fail making eventlet unusable at all. See
# https://github.com/eventlet/eventlet/issues/736 for details.
self._cached_resolver = None
@property
def _resolver(self):
if self._cached_resolver is None:
self.clear()
return self._cached_resolver
@_resolver.setter
def _resolver(self, value):
self._cached_resolver = value
def clear(self):
self._resolver = dns.resolver.Resolver(filename=self._filename)
self._resolver.cache = dns.resolver.LRUCache()
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True,
_hosts_rdtypes=(dns.rdatatype.A, dns.rdatatype.AAAA),
use_network=True):
"""Query the resolver, using /etc/hosts if enabled.
Behavior:
1. if hosts is enabled and contains answer, return it now
2. query nameservers for qname if use_network is True
3. if qname did not contain dots, pretend it was top-level domain,
query "foobar." and append to previous result
"""
result = [None, None, 0]
if qname is None:
qname = '0.0.0.0'
if isinstance(qname, six.string_types) or isinstance(qname, six.binary_type):
qname = dns.name.from_text(qname, None)
def step(fun, *args, **kwargs):
try:
a = fun(*args, **kwargs)
except Exception as e:
result[1] = e
return False
if a.rrset is not None and len(a.rrset):
if result[0] is None:
result[0] = a
else:
result[0].rrset.union_update(a.rrset)
result[2] += len(a.rrset)
return True
def end():
if result[0] is not None:
if raise_on_no_answer and result[2] == 0:
raise dns.resolver.NoAnswer
return result[0]
if result[1] is not None:
if raise_on_no_answer or not isinstance(result[1], dns.resolver.NoAnswer):
raise result[1]
raise dns.resolver.NXDOMAIN(qnames=(qname,))
if (self._hosts and (rdclass == dns.rdataclass.IN) and (rdtype in _hosts_rdtypes)):
if step(self._hosts.query, qname, rdtype, raise_on_no_answer=False):
if (result[0] is not None) or (result[1] is not None) or (not use_network):
return end()
# Main query
step(self._resolver.query, qname, rdtype, rdclass, tcp, source, raise_on_no_answer=False)
# `resolv.conf` docs say unqualified names must resolve from search (or local) domain.
# However, common OS `getaddrinfo()` implementations append trailing dot (e.g. `db -> db.`)
# and ask nameservers, as if top-level domain was queried.
# This step follows established practice.
# https://github.com/nameko/nameko/issues/392
# https://github.com/eventlet/eventlet/issues/363
if len(qname) == 1:
step(self._resolver.query, qname.concatenate(dns.name.root),
rdtype, rdclass, tcp, source, raise_on_no_answer=False)
return end()
def getaliases(self, hostname):
"""Return a list of all the aliases of a given hostname"""
if self._hosts:
aliases = self._hosts.getaliases(hostname)
else:
aliases = []
while True:
try:
ans = self._resolver.query(hostname, dns.rdatatype.CNAME)
except (dns.resolver.NoAnswer, dns.resolver.NXDOMAIN):
break
else:
aliases.extend(str(rr.target) for rr in ans.rrset)
hostname = ans[0].target
return aliases
resolver = ResolverProxy(hosts_resolver=HostsResolver())
def resolve(name, family=socket.AF_INET, raises=True, _proxy=None,
use_network=True):
"""Resolve a name for a given family using the global resolver proxy.
This method is called by the global getaddrinfo() function. If use_network
is False, only resolution via hosts file will be performed.
Return a dns.resolver.Answer instance. If there is no answer it's
rrset will be emtpy.
"""
if family == socket.AF_INET:
rdtype = dns.rdatatype.A
elif family == socket.AF_INET6:
rdtype = dns.rdatatype.AAAA
else:
raise socket.gaierror(socket.EAI_FAMILY,
'Address family not supported')
if _proxy is None:
_proxy = resolver
try:
try:
return _proxy.query(name, rdtype, raise_on_no_answer=raises,
use_network=use_network)
except dns.resolver.NXDOMAIN:
if not raises:
return HostsAnswer(dns.name.Name(name),
rdtype, dns.rdataclass.IN, None, False)
raise
except dns.exception.Timeout:
_raise_new_error(EAI_EAGAIN_ERROR)
except dns.exception.DNSException:
_raise_new_error(EAI_NODATA_ERROR)
def resolve_cname(host):
"""Return the canonical name of a hostname"""
try:
ans = resolver.query(host, dns.rdatatype.CNAME)
except dns.resolver.NoAnswer:
return host
except dns.exception.Timeout:
_raise_new_error(EAI_EAGAIN_ERROR)
except dns.exception.DNSException:
_raise_new_error(EAI_NODATA_ERROR)
else:
return str(ans[0].target)
def getaliases(host):
"""Return a list of for aliases for the given hostname
This method does translate the dnspython exceptions into
socket.gaierror exceptions. If no aliases are available an empty
list will be returned.
"""
try:
return resolver.getaliases(host)
except dns.exception.Timeout:
_raise_new_error(EAI_EAGAIN_ERROR)
except dns.exception.DNSException:
_raise_new_error(EAI_NODATA_ERROR)
def _getaddrinfo_lookup(host, family, flags):
"""Resolve a hostname to a list of addresses
Helper function for getaddrinfo.
"""
if flags & socket.AI_NUMERICHOST:
_raise_new_error(EAI_NONAME_ERROR)
addrs = []
if family == socket.AF_UNSPEC:
err = None
for use_network in [False, True]:
for qfamily in [socket.AF_INET6, socket.AF_INET]:
try:
answer = resolve(host, qfamily, False, use_network=use_network)
except socket.gaierror as e:
if e.errno not in (socket.EAI_AGAIN, EAI_NONAME_ERROR.errno, EAI_NODATA_ERROR.errno):
raise
err = e
else:
if answer.rrset:
addrs.extend(rr.address for rr in answer.rrset)
if addrs:
break
if err is not None and not addrs:
raise err
elif family == socket.AF_INET6 and flags & socket.AI_V4MAPPED:
answer = resolve(host, socket.AF_INET6, False)
if answer.rrset:
addrs = [rr.address for rr in answer.rrset]
if not addrs or flags & socket.AI_ALL:
answer = resolve(host, socket.AF_INET, False)
if answer.rrset:
addrs = ['::ffff:' + rr.address for rr in answer.rrset]
else:
answer = resolve(host, family, False)
if answer.rrset:
addrs = [rr.address for rr in answer.rrset]
return str(answer.qname), addrs
def getaddrinfo(host, port, family=0, socktype=0, proto=0, flags=0):
"""Replacement for Python's socket.getaddrinfo
This does the A and AAAA lookups asynchronously after which it
calls the OS' getaddrinfo(3) using the AI_NUMERICHOST flag. This
flag ensures getaddrinfo(3) does not use the network itself and
allows us to respect all the other arguments like the native OS.
"""
if isinstance(host, six.string_types):
host = host.encode('idna').decode('ascii')
elif isinstance(host, six.binary_type):
host = host.decode("ascii")
if host is not None and not is_ip_addr(host):
qname, addrs = _getaddrinfo_lookup(host, family, flags)
else:
qname = host
addrs = [host]
aiflags = (flags | socket.AI_NUMERICHOST) & (0xffff ^ socket.AI_CANONNAME)
res = []
err = None
for addr in addrs:
try:
ai = socket.getaddrinfo(addr, port, family,
socktype, proto, aiflags)
except socket.error as e:
if flags & socket.AI_ADDRCONFIG:
err = e
continue
raise
res.extend(ai)
if not res:
if err:
raise err
raise socket.gaierror(socket.EAI_NONAME, 'No address found')
if flags & socket.AI_CANONNAME:
if not is_ip_addr(qname):
qname = resolve_cname(qname).encode('ascii').decode('idna')
ai = res[0]
res[0] = (ai[0], ai[1], ai[2], qname, ai[4])
return res
def gethostbyname(hostname):
"""Replacement for Python's socket.gethostbyname"""
if is_ipv4_addr(hostname):
return hostname
rrset = resolve(hostname)
return rrset[0].address
def gethostbyname_ex(hostname):
"""Replacement for Python's socket.gethostbyname_ex"""
if is_ipv4_addr(hostname):
return (hostname, [], [hostname])
ans = resolve(hostname)
aliases = getaliases(hostname)
addrs = [rr.address for rr in ans.rrset]
qname = str(ans.qname)
if qname[-1] == '.':
qname = qname[:-1]
return (qname, aliases, addrs)
def getnameinfo(sockaddr, flags):
"""Replacement for Python's socket.getnameinfo.
Currently only supports IPv4.
"""
try:
host, port = sockaddr
except (ValueError, TypeError):
if not isinstance(sockaddr, tuple):
del sockaddr # to pass a stdlib test that is
# hyper-careful about reference counts
raise TypeError('getnameinfo() argument 1 must be a tuple')
else:
# must be ipv6 sockaddr, pretending we don't know how to resolve it
_raise_new_error(EAI_NONAME_ERROR)
if (flags & socket.NI_NAMEREQD) and (flags & socket.NI_NUMERICHOST):
# Conflicting flags. Punt.
_raise_new_error(EAI_NONAME_ERROR)
if is_ipv4_addr(host):
try:
rrset = resolver.query(
dns.reversename.from_address(host), dns.rdatatype.PTR)
if len(rrset) > 1:
raise socket.error('sockaddr resolved to multiple addresses')
host = rrset[0].target.to_text(omit_final_dot=True)
except dns.exception.Timeout:
if flags & socket.NI_NAMEREQD:
_raise_new_error(EAI_EAGAIN_ERROR)
except dns.exception.DNSException:
if flags & socket.NI_NAMEREQD:
_raise_new_error(EAI_NONAME_ERROR)
else:
try:
rrset = resolver.query(host)
if len(rrset) > 1:
raise socket.error('sockaddr resolved to multiple addresses')
if flags & socket.NI_NUMERICHOST:
host = rrset[0].address
except dns.exception.Timeout:
_raise_new_error(EAI_EAGAIN_ERROR)
except dns.exception.DNSException:
raise socket.gaierror(
(socket.EAI_NODATA, 'No address associated with hostname'))
if not (flags & socket.NI_NUMERICSERV):
proto = (flags & socket.NI_DGRAM) and 'udp' or 'tcp'
port = socket.getservbyport(port, proto)
return (host, port)
def _net_read(sock, count, expiration):
"""coro friendly replacement for dns.query._net_read
Read the specified number of bytes from sock. Keep trying until we
either get the desired amount, or we hit EOF.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
s = bytearray()
while count > 0:
try:
n = sock.recv(count)
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
eventlet.sleep(0.01)
continue
if n == b'':
raise EOFError
count = count - len(n)
s += n
return s
def _net_write(sock, data, expiration):
"""coro friendly replacement for dns.query._net_write
Write the specified data to the socket.
A Timeout exception will be raised if the operation is not completed
by the expiration time.
"""
current = 0
l = len(data)
while current < l:
try:
current += sock.send(data[current:])
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
# Test if raise_on_truncation is an argument we should handle.
# It was newly added in dnspython 2.0
try:
dns.message.from_wire("", raise_on_truncation=True)
except dns.message.ShortHeader:
_handle_raise_on_truncation = True
except TypeError:
# Argument error, there is no argument "raise_on_truncation"
_handle_raise_on_truncation = False
def udp(q, where, timeout=DNS_QUERY_TIMEOUT, port=53,
af=None, source=None, source_port=0, ignore_unexpected=False,
one_rr_per_rrset=False, ignore_trailing=False,
raise_on_truncation=False, sock=None):
"""coro friendly replacement for dns.query.udp
Return the response obtained after sending a query via UDP.
@param q: the query
@type q: dns.message.Message
@param where: where to send the message
@type where: string containing an IPv4 or IPv6 address
@param timeout: The number of seconds to wait before the query times out.
If None, the default, wait forever.
@type timeout: float
@param port: The port to which to send the message. The default is 53.
@type port: int
@param af: the address family to use. The default is None, which
causes the address family to use to be inferred from the form of of where.
If the inference attempt fails, AF_INET is used.
@type af: int
@rtype: dns.message.Message object
@param source: source address. The default is the IPv4 wildcard address.
@type source: string
@param source_port: The port from which to send the message.
The default is 0.
@type source_port: int
@param ignore_unexpected: If True, ignore responses from unexpected
sources. The default is False.
@type ignore_unexpected: bool
@param one_rr_per_rrset: If True, put each RR into its own
RRset.
@type one_rr_per_rrset: bool
@param ignore_trailing: If True, ignore trailing
junk at end of the received message.
@type ignore_trailing: bool
@param raise_on_truncation: If True, raise an exception if
the TC bit is set.
@type raise_on_truncation: bool
@param sock: the socket to use for the
query. If None, the default, a socket is created. Note that
if a socket is provided, it must be a nonblocking datagram socket,
and the source and source_port are ignored.
@type sock: socket.socket | None"""
wire = q.to_wire()
if af is None:
try:
af = dns.inet.af_for_address(where)
except:
af = dns.inet.AF_INET
if af == dns.inet.AF_INET:
destination = (where, port)
if source is not None:
source = (source, source_port)
elif af == dns.inet.AF_INET6:
# Purge any stray zeroes in source address. When doing the tuple comparison
# below, we need to always ensure both our target and where we receive replies
# from are compared with all zeroes removed so that we don't erroneously fail.
# e.g. ('00::1', 53, 0, 0) != ('::1', 53, 0, 0)
where_trunc = dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(where))
destination = (where_trunc, port, 0, 0)
if source is not None:
source = (source, source_port, 0, 0)
if sock:
s = sock
else:
s = socket.socket(af, socket.SOCK_DGRAM)
s.settimeout(timeout)
try:
expiration = compute_expiration(dns.query, timeout)
if source is not None:
s.bind(source)
while True:
try:
s.sendto(wire, destination)
break
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
eventlet.sleep(0.01)
continue
tried = False
while True:
# If we've tried to receive at least once, check to see if our
# timer expired
if tried and (expiration - time.time() <= 0.0):
raise dns.exception.Timeout
# Sleep if we are retrying the operation due to a bad source
# address or a socket timeout.
if tried:
eventlet.sleep(0.01)
tried = True
try:
(wire, from_address) = s.recvfrom(65535)
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
continue
if dns.inet.af_for_address(from_address[0]) == dns.inet.AF_INET6:
# Purge all possible zeroes for ipv6 to match above logic
addr = from_address[0]
addr = dns.ipv6.inet_ntoa(dns.ipv6.inet_aton(addr))
from_address = (addr, from_address[1], from_address[2], from_address[3])
if from_address == destination:
break
if not ignore_unexpected:
raise dns.query.UnexpectedSource(
'got a response from %s instead of %s'
% (from_address, destination))
finally:
s.close()
if _handle_raise_on_truncation:
r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing,
raise_on_truncation=raise_on_truncation)
else:
r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing)
if not q.is_response(r):
raise dns.query.BadResponse()
return r
def tcp(q, where, timeout=DNS_QUERY_TIMEOUT, port=53,
af=None, source=None, source_port=0,
one_rr_per_rrset=False, ignore_trailing=False, sock=None):
"""coro friendly replacement for dns.query.tcp
Return the response obtained after sending a query via TCP.
@param q: the query
@type q: dns.message.Message object
@param where: where to send the message
@type where: string containing an IPv4 or IPv6 address
@param timeout: The number of seconds to wait before the query times out.
If None, the default, wait forever.
@type timeout: float
@param port: The port to which to send the message. The default is 53.
@type port: int
@param af: the address family to use. The default is None, which
causes the address family to use to be inferred from the form of of where.
If the inference attempt fails, AF_INET is used.
@type af: int
@rtype: dns.message.Message object
@param source: source address. The default is the IPv4 wildcard address.
@type source: string
@param source_port: The port from which to send the message.
The default is 0.
@type source_port: int
@type ignore_unexpected: bool
@param one_rr_per_rrset: If True, put each RR into its own
RRset.
@type one_rr_per_rrset: bool
@param ignore_trailing: If True, ignore trailing
junk at end of the received message.
@type ignore_trailing: bool
@param sock: the socket to use for the
query. If None, the default, a socket is created. Note that
if a socket is provided, it must be a nonblocking datagram socket,
and the source and source_port are ignored.
@type sock: socket.socket | None"""
wire = q.to_wire()
if af is None:
try:
af = dns.inet.af_for_address(where)
except:
af = dns.inet.AF_INET
if af == dns.inet.AF_INET:
destination = (where, port)
if source is not None:
source = (source, source_port)
elif af == dns.inet.AF_INET6:
destination = (where, port, 0, 0)
if source is not None:
source = (source, source_port, 0, 0)
if sock:
s = sock
else:
s = socket.socket(af, socket.SOCK_STREAM)
s.settimeout(timeout)
try:
expiration = compute_expiration(dns.query, timeout)
if source is not None:
s.bind(source)
while True:
try:
s.connect(destination)
break
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
eventlet.sleep(0.01)
continue
l = len(wire)
# copying the wire into tcpmsg is inefficient, but lets us
# avoid writev() or doing a short write that would get pushed
# onto the net
tcpmsg = struct.pack("!H", l) + wire
_net_write(s, tcpmsg, expiration)
ldata = _net_read(s, 2, expiration)
(l,) = struct.unpack("!H", ldata)
wire = bytes(_net_read(s, l, expiration))
finally:
s.close()
r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac,
one_rr_per_rrset=one_rr_per_rrset,
ignore_trailing=ignore_trailing)
if not q.is_response(r):
raise dns.query.BadResponse()
return r
def reset():
resolver.clear()
# Install our coro-friendly replacements for the tcp and udp query methods.
dns.query.tcp = tcp
dns.query.udp = udp