/usr/lib/python2.7/dist-packages/eventlet/support/greendns.py is in python-eventlet 0.20.0-4.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 | '''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 struct
import sys
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.support 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.
# if (module_name + '.').startswith('dns.'):
# module_name = 'eventlet.support.' + module_name
modules = {
'select': select,
'time': time,
'os': os,
'socket': _socket_nodns,
}
return patcher.import_patched(module_name, **modules)
sys.path.insert(0, os.path.abspath(os.path.dirname(__file__)))
dns = import_patched('dns')
for pkg in dns.__all__:
setattr(dns, pkg, import_patched('dns.' + pkg))
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))
del import_patched
sys.path.pop(0)
socket = _socket_nodns
DNS_QUERY_TIMEOUT = 10.0
HOSTS_TTL = 10.0
EAI_EAGAIN_ERROR = socket.gaierror(socket.EAI_AGAIN, 'Lookup timed out')
EAI_NODATA_ERROR = socket.gaierror(socket.EAI_NODATA, 'No address associated with hostname')
EAI_NONAME_ERROR = socket.gaierror(socket.EAI_NONAME, 'Name or service not known')
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)
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
"""
def __init__(self, fname=None, interval=HOSTS_TTL):
self._v4 = {} # name -> ipv4
self._v6 = {} # name -> ipv6
self._aliases = {} # name -> cannonical_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.
"""
lines = []
try:
with open(self.fname, 'rU') as fp:
for line in fp:
line = line.strip()
if line and line[0] != '#':
lines.append(line)
except (IOError, OSError):
pass
return lines
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)
ipmap[cname] = ip
for alias in parts:
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)
else:
name = str(qname)
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
self.clear()
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):
"""Query the resolver, using /etc/hosts if enabled"""
if qname is None:
qname = '0.0.0.0'
if rdclass == dns.rdataclass.IN and self._hosts:
try:
return self._hosts.query(qname, rdtype)
except dns.resolver.NoAnswer:
pass
return self._resolver.query(qname, rdtype, rdclass,
tcp, source, raise_on_no_answer)
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):
"""Resolve a name for a given family using the global resolver proxy
This method is called by the global getaddrinfo() function.
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')
try:
try:
return resolver.query(name, rdtype, raise_on_no_answer=raises)
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 EAI_EAGAIN_ERROR
except dns.exception.DNSException:
raise 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 EAI_EAGAIN_ERROR
except dns.exception.DNSException:
raise 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 EAI_EAGAIN_ERROR
except dns.exception.DNSException:
raise 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 EAI_NONAME_ERROR
addrs = []
if family == socket.AF_UNSPEC:
err = None
for qfamily in [socket.AF_INET6, socket.AF_INET]:
try:
answer = resolve(host, qfamily, False)
except socket.gaierror as e:
if e.errno not in (socket.EAI_AGAIN, socket.EAI_NODATA):
raise
err = e
else:
if answer.rrset:
addrs.extend(rr.address for rr in answer.rrset)
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')
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 EAI_NONAME_ERROR
if (flags & socket.NI_NAMEREQD) and (flags & socket.NI_NUMERICHOST):
# Conflicting flags. Punt.
raise 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 EAI_EAGAIN_ERROR
except dns.exception.DNSException:
if flags & socket.NI_NAMEREQD:
raise 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 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_write
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 = ''
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
if n == '':
raise EOFError
count = count - len(n)
s = 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
def udp(q, where, timeout=DNS_QUERY_TIMEOUT, port=53,
af=None, source=None, source_port=0, ignore_unexpected=False):
"""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"""
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)
s = socket.socket(af, socket.SOCK_DGRAM)
s.settimeout(timeout)
try:
expiration = dns.query._compute_expiration(timeout)
if source is not None:
s.bind(source)
try:
s.sendto(wire, destination)
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
while 1:
try:
(wire, from_address) = s.recvfrom(65535)
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
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()
r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac)
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):
"""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"""
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)
s = socket.socket(af, socket.SOCK_STREAM)
s.settimeout(timeout)
try:
expiration = dns.query._compute_expiration(timeout)
if source is not None:
s.bind(source)
try:
s.connect(destination)
except socket.timeout:
# Q: Do we also need to catch coro.CoroutineSocketWake and pass?
if expiration - time.time() <= 0.0:
raise dns.exception.Timeout
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 = _net_read(s, l, expiration)
finally:
s.close()
r = dns.message.from_wire(wire, keyring=q.keyring, request_mac=q.mac)
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
|