/usr/lib/python3/dist-packages/dns/resolver.py is in python3-dnspython 1.11.1-1.
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 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 555 556 557 558 559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650 651 652 653 654 655 656 657 658 659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692 693 694 695 696 697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712 713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915 916 917 918 919 920 921 922 923 924 925 926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955 956 957 958 959 960 961 962 963 964 965 966 967 968 969 970 971 972 973 974 975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221 1222 1223 1224 1225 1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 | # Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""DNS stub resolver.
@var default_resolver: The default resolver object
@type default_resolver: dns.resolver.Resolver object"""
import socket
import sys
import time
try:
import threading as _threading
except ImportError:
import dummy_threading as _threading
import dns.exception
import dns.flags
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
if sys.platform == 'win32':
try:
import winreg as _winreg
except ImportError:
import _winreg
class NXDOMAIN(dns.exception.DNSException):
"""The query name does not exist."""
pass
class YXDOMAIN(dns.exception.DNSException):
"""The query name is too long after DNAME substitution."""
pass
# The definition of the Timeout exception has moved from here to the
# dns.exception module. We keep dns.resolver.Timeout defined for
# backwards compatibility.
Timeout = dns.exception.Timeout
class NoAnswer(dns.exception.DNSException):
"""The response did not contain an answer to the question."""
pass
class NoNameservers(dns.exception.DNSException):
"""No non-broken nameservers are available to answer the query."""
pass
class NotAbsolute(dns.exception.DNSException):
"""Raised if an absolute domain name is required but a relative name
was provided."""
pass
class NoRootSOA(dns.exception.DNSException):
"""Raised if for some reason there is no SOA at the root name.
This should never happen!"""
pass
class NoMetaqueries(dns.exception.DNSException):
"""Metaqueries are not allowed."""
pass
class Answer(object):
"""DNS stub resolver answer
Instances of this class bundle up the result of a successful DNS
resolution.
For convenience, the answer object implements much of the sequence
protocol, forwarding to its rrset. E.g. "for a in answer" is
equivalent to "for a in answer.rrset", "answer[i]" is equivalent
to "answer.rrset[i]", and "answer[i:j]" is equivalent to
"answer.rrset[i:j]".
Note that CNAMEs or DNAMEs in the response may mean that answer
node's name might not be the query name.
@ivar qname: The query name
@type qname: dns.name.Name object
@ivar rdtype: The query type
@type rdtype: int
@ivar rdclass: The query class
@type rdclass: int
@ivar response: The response message
@type response: dns.message.Message object
@ivar rrset: The answer
@type rrset: dns.rrset.RRset object
@ivar expiration: The time when the answer expires
@type expiration: float (seconds since the epoch)
@ivar canonical_name: The canonical name of the query name
@type canonical_name: dns.name.Name object
"""
def __init__(self, qname, rdtype, rdclass, response,
raise_on_no_answer=True):
self.qname = qname
self.rdtype = rdtype
self.rdclass = rdclass
self.response = response
min_ttl = -1
rrset = None
for count in range(0, 15):
try:
rrset = response.find_rrset(response.answer, qname,
rdclass, rdtype)
if min_ttl == -1 or rrset.ttl < min_ttl:
min_ttl = rrset.ttl
break
except KeyError:
if rdtype != dns.rdatatype.CNAME:
try:
crrset = response.find_rrset(response.answer,
qname,
rdclass,
dns.rdatatype.CNAME)
if min_ttl == -1 or crrset.ttl < min_ttl:
min_ttl = crrset.ttl
for rd in crrset:
qname = rd.target
break
continue
except KeyError:
if raise_on_no_answer:
raise NoAnswer
if raise_on_no_answer:
raise NoAnswer
if rrset is None and raise_on_no_answer:
raise NoAnswer
self.canonical_name = qname
self.rrset = rrset
if rrset is None:
while 1:
# Look for a SOA RR whose owner name is a superdomain
# of qname.
try:
srrset = response.find_rrset(response.authority, qname,
rdclass, dns.rdatatype.SOA)
if min_ttl == -1 or srrset.ttl < min_ttl:
min_ttl = srrset.ttl
if srrset[0].minimum < min_ttl:
min_ttl = srrset[0].minimum
break
except KeyError:
try:
qname = qname.parent()
except dns.name.NoParent:
break
self.expiration = time.time() + min_ttl
def __getattr__(self, attr):
if attr == 'name':
return self.rrset.name
elif attr == 'ttl':
return self.rrset.ttl
elif attr == 'covers':
return self.rrset.covers
elif attr == 'rdclass':
return self.rrset.rdclass
elif attr == 'rdtype':
return self.rrset.rdtype
else:
raise AttributeError(attr)
def __len__(self):
return len(self.rrset)
def __iter__(self):
return iter(self.rrset)
def __getitem__(self, i):
return self.rrset[i]
def __delitem__(self, i):
del self.rrset[i]
def __getslice__(self, i, j):
return self.rrset[i:j]
def __delslice__(self, i, j):
del self.rrset[i:j]
class Cache(object):
"""Simple DNS answer cache.
@ivar data: A dictionary of cached data
@type data: dict
@ivar cleaning_interval: The number of seconds between cleanings. The
default is 300 (5 minutes).
@type cleaning_interval: float
@ivar next_cleaning: The time the cache should next be cleaned (in seconds
since the epoch.)
@type next_cleaning: float
"""
def __init__(self, cleaning_interval=300.0):
"""Initialize a DNS cache.
@param cleaning_interval: the number of seconds between periodic
cleanings. The default is 300.0
@type cleaning_interval: float.
"""
self.data = {}
self.cleaning_interval = cleaning_interval
self.next_cleaning = time.time() + self.cleaning_interval
self.lock = _threading.Lock()
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 I{key}. Returns None if
no answer is cached for the key.
@param key: the key
@type key: (dns.name.Name, int, int) tuple whose values are the
query name, rdtype, and rdclass.
@rtype: dns.resolver.Answer object or None
"""
try:
self.lock.acquire()
self._maybe_clean()
v = self.data.get(key)
if v is None or v.expiration <= time.time():
return None
return v
finally:
self.lock.release()
def put(self, key, value):
"""Associate key and value in the cache.
@param key: the key
@type key: (dns.name.Name, int, int) tuple whose values are the
query name, rdtype, and rdclass.
@param value: The answer being cached
@type value: dns.resolver.Answer object
"""
try:
self.lock.acquire()
self._maybe_clean()
self.data[key] = value
finally:
self.lock.release()
def flush(self, key=None):
"""Flush the cache.
If I{key} is specified, only that item is flushed. Otherwise
the entire cache is flushed.
@param key: the key to flush
@type key: (dns.name.Name, int, int) tuple or None
"""
try:
self.lock.acquire()
if not key is None:
if key in self.data:
del self.data[key]
else:
self.data = {}
self.next_cleaning = time.time() + self.cleaning_interval
finally:
self.lock.release()
class LRUCacheNode(object):
"""LRUCache node.
"""
def __init__(self, key, value):
self.key = key
self.value = value
self.prev = self
self.next = self
def link_before(self, node):
self.prev = node.prev
self.next = node
node.prev.next = self
node.prev = 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(object):
"""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.
@ivar data: A dictionary of cached data
@type data: dict
@ivar sentinel: sentinel node for circular doubly linked list of nodes
@type sentinel: LRUCacheNode object
@ivar max_size: The maximum number of nodes
@type max_size: int
"""
def __init__(self, max_size=100000):
"""Initialize a DNS cache.
@param max_size: The maximum number of nodes to cache; the default is 100000. Must be > 1.
@type max_size: int
"""
self.data = {}
self.set_max_size(max_size)
self.sentinel = LRUCacheNode(None, None)
self.lock = _threading.Lock()
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 I{key}. Returns None if
no answer is cached for the key.
@param key: the key
@type key: (dns.name.Name, int, int) tuple whose values are the
query name, rdtype, and rdclass.
@rtype: dns.resolver.Answer object or None
"""
try:
self.lock.acquire()
node = self.data.get(key)
if node is None:
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]
return None
node.link_after(self.sentinel)
return node.value
finally:
self.lock.release()
def put(self, key, value):
"""Associate key and value in the cache.
@param key: the key
@type key: (dns.name.Name, int, int) tuple whose values are the
query name, rdtype, and rdclass.
@param value: The answer being cached
@type value: dns.resolver.Answer object
"""
try:
self.lock.acquire()
node = self.data.get(key)
if not node is 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
finally:
self.lock.release()
def flush(self, key=None):
"""Flush the cache.
If I{key} is specified, only that item is flushed. Otherwise
the entire cache is flushed.
@param key: the key to flush
@type key: (dns.name.Name, int, int) tuple or None
"""
try:
self.lock.acquire()
if not key is None:
node = self.data.get(key)
if not node is None:
node.unlink()
del self.data[node.key]
else:
node = self.sentinel.next
while node != self.sentinel:
next = node.next
node.prev = None
node.next = None
node = next
self.data = {}
finally:
self.lock.release()
class Resolver(object):
"""DNS stub resolver
@ivar domain: The domain of this host
@type domain: dns.name.Name object
@ivar nameservers: A list of nameservers to query. Each nameserver is
a string which contains the IP address of a nameserver.
@type nameservers: list of strings
@ivar search: The search list. If the query name is a relative name,
the resolver will construct an absolute query name by appending the search
names one by one to the query name.
@type search: list of dns.name.Name objects
@ivar port: The port to which to send queries. The default is 53.
@type port: int
@ivar timeout: The number of seconds to wait for a response from a
server, before timing out.
@type timeout: float
@ivar lifetime: The total number of seconds to spend trying to get an
answer to the question. If the lifetime expires, a Timeout exception
will occur.
@type lifetime: float
@ivar keyring: The TSIG keyring to use. The default is None.
@type keyring: dict
@ivar keyname: The TSIG keyname to use. The default is None.
@type keyname: dns.name.Name object
@ivar keyalgorithm: The TSIG key algorithm to use. The default is
dns.tsig.default_algorithm.
@type keyalgorithm: string
@ivar edns: The EDNS level to use. The default is -1, no Edns.
@type edns: int
@ivar ednsflags: The EDNS flags
@type ednsflags: int
@ivar payload: The EDNS payload size. The default is 0.
@type payload: int
@ivar flags: The message flags to use. The default is None (i.e. not overwritten)
@type flags: int
@ivar cache: The cache to use. The default is None.
@type cache: dns.resolver.Cache object
@ivar retry_servfail: should we retry a nameserver if it says SERVFAIL?
The default is 'false'.
@type retry_servfail: bool
"""
def __init__(self, filename='/etc/resolv.conf', configure=True):
"""Initialize a resolver instance.
@param filename: The filename of a configuration file in
standard /etc/resolv.conf format. This parameter is meaningful
only when I{configure} is true and the platform is POSIX.
@type filename: string or file object
@param configure: If True (the default), the resolver instance
is configured in the normal fashion for the operating system
the resolver is running on. (I.e. a /etc/resolv.conf file on
POSIX systems and from the registry on Windows systems.)
@type configure: bool"""
self.reset()
if configure:
if sys.platform == 'win32':
self.read_registry()
elif filename:
self.read_resolv_conf(filename)
def reset(self):
"""Reset all resolver configuration to the defaults."""
self.domain = \
dns.name.Name(dns.name.from_text(socket.gethostname())[1:])
if len(self.domain) == 0:
self.domain = dns.name.root
self.nameservers = []
self.search = []
self.port = 53
self.timeout = 2.0
self.lifetime = 30.0
self.keyring = None
self.keyname = None
self.keyalgorithm = dns.tsig.default_algorithm
self.edns = -1
self.ednsflags = 0
self.payload = 0
self.cache = None
self.flags = None
self.retry_servfail = False
def read_resolv_conf(self, f):
"""Process f as a file in the /etc/resolv.conf format. If f is
a string, it is used as the name of the file to open; otherwise it
is treated as the file itself."""
if isinstance(f, str):
try:
f = open(f, 'r')
except IOError:
# /etc/resolv.conf doesn't exist, can't be read, etc.
# We'll just use the default resolver configuration.
self.nameservers = ['127.0.0.1']
return
want_close = True
else:
want_close = False
try:
for l in f:
if len(l) == 0 or l[0] == '#' or l[0] == ';':
continue
tokens = l.split()
if len(tokens) == 0:
continue
if tokens[0] == 'nameserver':
self.nameservers.append(tokens[1])
elif tokens[0] == 'domain':
self.domain = dns.name.from_text(tokens[1])
elif tokens[0] == 'search':
for suffix in tokens[1:]:
self.search.append(dns.name.from_text(suffix))
finally:
if want_close:
f.close()
if len(self.nameservers) == 0:
self.nameservers.append('127.0.0.1')
def _determine_split_char(self, entry):
#
# The windows registry irritatingly changes the list element
# delimiter in between ' ' and ',' (and vice-versa) in various
# versions of windows.
#
if entry.find(' ') >= 0:
split_char = ' '
elif entry.find(',') >= 0:
split_char = ','
else:
# probably a singleton; treat as a space-separated list.
split_char = ' '
return split_char
def _config_win32_nameservers(self, nameservers):
"""Configure a NameServer registry entry."""
split_char = self._determine_split_char(nameservers)
ns_list = nameservers.split(split_char)
for ns in ns_list:
if not ns in self.nameservers:
self.nameservers.append(ns)
def _config_win32_domain(self, domain):
"""Configure a Domain registry entry."""
self.domain = dns.name.from_text(domain)
def _config_win32_search(self, search):
"""Configure a Search registry entry."""
split_char = self._determine_split_char(search)
search_list = search.split(split_char)
for s in search_list:
if not s in self.search:
self.search.append(dns.name.from_text(s))
def _config_win32_fromkey(self, key):
"""Extract DNS info from a registry key."""
try:
servers, rtype = _winreg.QueryValueEx(key, 'NameServer')
except WindowsError:
servers = None
if servers:
self._config_win32_nameservers(servers)
try:
dom, rtype = _winreg.QueryValueEx(key, 'Domain')
if dom:
self._config_win32_domain(dom)
except WindowsError:
pass
else:
try:
servers, rtype = _winreg.QueryValueEx(key, 'DhcpNameServer')
except WindowsError:
servers = None
if servers:
self._config_win32_nameservers(servers)
try:
dom, rtype = _winreg.QueryValueEx(key, 'DhcpDomain')
if dom:
self._config_win32_domain(dom)
except WindowsError:
pass
try:
search, rtype = _winreg.QueryValueEx(key, 'SearchList')
except WindowsError:
search = None
if search:
self._config_win32_search(search)
def read_registry(self):
"""Extract resolver configuration from the Windows registry."""
lm = _winreg.ConnectRegistry(None, _winreg.HKEY_LOCAL_MACHINE)
want_scan = False
try:
try:
# XP, 2000
tcp_params = _winreg.OpenKey(lm,
r'SYSTEM\CurrentControlSet'
r'\Services\Tcpip\Parameters')
want_scan = True
except EnvironmentError:
# ME
tcp_params = _winreg.OpenKey(lm,
r'SYSTEM\CurrentControlSet'
r'\Services\VxD\MSTCP')
try:
self._config_win32_fromkey(tcp_params)
finally:
tcp_params.Close()
if want_scan:
interfaces = _winreg.OpenKey(lm,
r'SYSTEM\CurrentControlSet'
r'\Services\Tcpip\Parameters'
r'\Interfaces')
try:
i = 0
while True:
try:
guid = _winreg.EnumKey(interfaces, i)
i += 1
key = _winreg.OpenKey(interfaces, guid)
if not self._win32_is_nic_enabled(lm, guid, key):
continue
try:
self._config_win32_fromkey(key)
finally:
key.Close()
except EnvironmentError:
break
finally:
interfaces.Close()
finally:
lm.Close()
def _win32_is_nic_enabled(self, lm, guid, interface_key):
# Look in the Windows Registry to determine whether the network
# interface corresponding to the given guid is enabled.
#
# (Code contributed by Paul Marks, thanks!)
#
try:
# This hard-coded location seems to be consistent, at least
# from Windows 2000 through Vista.
connection_key = _winreg.OpenKey(
lm,
r'SYSTEM\CurrentControlSet\Control\Network'
r'\{4D36E972-E325-11CE-BFC1-08002BE10318}'
r'\%s\Connection' % guid)
try:
# The PnpInstanceID points to a key inside Enum
(pnp_id, ttype) = _winreg.QueryValueEx(
connection_key, 'PnpInstanceID')
if ttype != _winreg.REG_SZ:
raise ValueError
device_key = _winreg.OpenKey(
lm, r'SYSTEM\CurrentControlSet\Enum\%s' % pnp_id)
try:
# Get ConfigFlags for this device
(flags, ttype) = _winreg.QueryValueEx(
device_key, 'ConfigFlags')
if ttype != _winreg.REG_DWORD:
raise ValueError
# Based on experimentation, bit 0x1 indicates that the
# device is disabled.
return not (flags & 0x1)
finally:
device_key.Close()
finally:
connection_key.Close()
except (EnvironmentError, ValueError):
# Pre-vista, enabled interfaces seem to have a non-empty
# NTEContextList; this was how dnspython detected enabled
# nics before the code above was contributed. We've retained
# the old method since we don't know if the code above works
# on Windows 95/98/ME.
try:
(nte, ttype) = _winreg.QueryValueEx(interface_key,
'NTEContextList')
return nte is not None
except WindowsError:
return False
def _compute_timeout(self, start):
now = time.time()
if now < start:
if start - now > 1:
# Time going backwards is bad. Just give up.
raise Timeout
else:
# Time went backwards, but only a little. This can
# happen, e.g. under vmware with older linux kernels.
# Pretend it didn't happen.
now = start
duration = now - start
if duration >= self.lifetime:
raise Timeout
return min(self.lifetime - duration, self.timeout)
def query(self, qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True, source_port=0):
"""Query nameservers to find the answer to the question.
The I{qname}, I{rdtype}, and I{rdclass} parameters may be objects
of the appropriate type, or strings that can be converted into objects
of the appropriate type. E.g. For I{rdtype} the integer 2 and the
the string 'NS' both mean to query for records with DNS rdata type NS.
@param qname: the query name
@type qname: dns.name.Name object or string
@param rdtype: the query type
@type rdtype: int or string
@param rdclass: the query class
@type rdclass: int or string
@param tcp: use TCP to make the query (default is False).
@type tcp: bool
@param source: bind to this IP address (defaults to machine default IP).
@type source: IP address in dotted quad notation
@param raise_on_no_answer: raise NoAnswer if there's no answer
(defaults is True).
@type raise_on_no_answer: bool
@param source_port: The port from which to send the message.
The default is 0.
@type source_port: int
@rtype: dns.resolver.Answer instance
@raises Timeout: no answers could be found in the specified lifetime
@raises NXDOMAIN: the query name does not exist
@raises YXDOMAIN: the query name is too long after DNAME substitution
@raises NoAnswer: the response did not contain an answer and
raise_on_no_answer is True.
@raises NoNameservers: no non-broken nameservers are available to
answer the question."""
if isinstance(qname, str):
qname = dns.name.from_text(qname, None)
if isinstance(rdtype, str):
rdtype = dns.rdatatype.from_text(rdtype)
if dns.rdatatype.is_metatype(rdtype):
raise NoMetaqueries
if isinstance(rdclass, str):
rdclass = dns.rdataclass.from_text(rdclass)
if dns.rdataclass.is_metaclass(rdclass):
raise NoMetaqueries
qnames_to_try = []
if qname.is_absolute():
qnames_to_try.append(qname)
else:
if len(qname) > 1:
qnames_to_try.append(qname.concatenate(dns.name.root))
if self.search:
for suffix in self.search:
qnames_to_try.append(qname.concatenate(suffix))
else:
qnames_to_try.append(qname.concatenate(self.domain))
all_nxdomain = True
start = time.time()
for qname in qnames_to_try:
if self.cache:
answer = self.cache.get((qname, rdtype, rdclass))
if not answer is None:
if answer.rrset is None and raise_on_no_answer:
raise NoAnswer
else:
return answer
request = dns.message.make_query(qname, rdtype, rdclass)
if not self.keyname is None:
request.use_tsig(self.keyring, self.keyname,
algorithm=self.keyalgorithm)
request.use_edns(self.edns, self.ednsflags, self.payload)
if self.flags is not None:
request.flags = self.flags
response = None
#
# make a copy of the servers list so we can alter it later.
#
nameservers = self.nameservers[:]
backoff = 0.10
while response is None:
if len(nameservers) == 0:
raise NoNameservers
for nameserver in nameservers[:]:
timeout = self._compute_timeout(start)
try:
if tcp:
response = dns.query.tcp(request, nameserver,
timeout, self.port,
source=source,
source_port=source_port)
else:
response = dns.query.udp(request, nameserver,
timeout, self.port,
source=source,
source_port=source_port)
if response.flags & dns.flags.TC:
# Response truncated; retry with TCP.
timeout = self._compute_timeout(start)
response = dns.query.tcp(request, nameserver,
timeout, self.port,
source=source,
source_port=source_port)
except (socket.error, dns.exception.Timeout):
#
# Communication failure or timeout. Go to the
# next server
#
response = None
continue
except dns.query.UnexpectedSource:
#
# Who knows? Keep going.
#
response = None
continue
except dns.exception.FormError:
#
# We don't understand what this server is
# saying. Take it out of the mix and
# continue.
#
nameservers.remove(nameserver)
response = None
continue
except EOFError:
#
# We're using TCP and they hung up on us.
# Probably they don't support TCP (though
# they're supposed to!). Take it out of the
# mix and continue.
#
nameservers.remove(nameserver)
response = None
continue
rcode = response.rcode()
if rcode == dns.rcode.YXDOMAIN:
raise YXDOMAIN
if rcode == dns.rcode.NOERROR or \
rcode == dns.rcode.NXDOMAIN:
break
#
# We got a response, but we're not happy with the
# rcode in it. Remove the server from the mix if
# the rcode isn't SERVFAIL.
#
if rcode != dns.rcode.SERVFAIL or not self.retry_servfail:
nameservers.remove(nameserver)
response = None
if not response is None:
break
#
# All nameservers failed!
#
if len(nameservers) > 0:
#
# But we still have servers to try. Sleep a bit
# so we don't pound them!
#
timeout = self._compute_timeout(start)
sleep_time = min(timeout, backoff)
backoff *= 2
time.sleep(sleep_time)
if response.rcode() == dns.rcode.NXDOMAIN:
continue
all_nxdomain = False
break
if all_nxdomain:
raise NXDOMAIN
answer = Answer(qname, rdtype, rdclass, response,
raise_on_no_answer)
if self.cache:
self.cache.put((qname, rdtype, rdclass), answer)
return answer
def use_tsig(self, keyring, keyname=None,
algorithm=dns.tsig.default_algorithm):
"""Add a TSIG signature to the query.
@param keyring: The TSIG keyring to use; defaults to None.
@type keyring: dict
@param keyname: The name of the TSIG key to use; defaults to None.
The key must be defined in the keyring. If a keyring is specified
but a keyname is not, then the key used will be the first key in the
keyring. Note that the order of keys in a dictionary is not defined,
so applications should supply a keyname when a keyring is used, unless
they know the keyring contains only one key.
@param algorithm: The TSIG key algorithm to use. The default
is dns.tsig.default_algorithm.
@type algorithm: string"""
self.keyring = keyring
if keyname is None:
self.keyname = next(iter(self.keyring.keys()))
else:
self.keyname = keyname
self.keyalgorithm = algorithm
def use_edns(self, edns, ednsflags, payload):
"""Configure Edns.
@param edns: The EDNS level to use. The default is -1, no Edns.
@type edns: int
@param ednsflags: The EDNS flags
@type ednsflags: int
@param payload: The EDNS payload size. The default is 0.
@type payload: int"""
if edns is None:
edns = -1
self.edns = edns
self.ednsflags = ednsflags
self.payload = payload
def set_flags(self, flags):
"""Overrides the default flags with your own
@param flags: The flags to overwrite the default with
@type flags: int"""
self.flags = flags
default_resolver = None
def get_default_resolver():
"""Get the default resolver, initializing it if necessary."""
global default_resolver
if default_resolver is None:
default_resolver = Resolver()
return default_resolver
def query(qname, rdtype=dns.rdatatype.A, rdclass=dns.rdataclass.IN,
tcp=False, source=None, raise_on_no_answer=True,
source_port=0):
"""Query nameservers to find the answer to the question.
This is a convenience function that uses the default resolver
object to make the query.
@see: L{dns.resolver.Resolver.query} for more information on the
parameters."""
return get_default_resolver().query(qname, rdtype, rdclass, tcp, source,
raise_on_no_answer, source_port)
def zone_for_name(name, rdclass=dns.rdataclass.IN, tcp=False, resolver=None):
"""Find the name of the zone which contains the specified name.
@param name: the query name
@type name: absolute dns.name.Name object or string
@param rdclass: The query class
@type rdclass: int
@param tcp: use TCP to make the query (default is False).
@type tcp: bool
@param resolver: the resolver to use
@type resolver: dns.resolver.Resolver object or None
@rtype: dns.name.Name"""
if isinstance(name, str):
name = dns.name.from_text(name, dns.name.root)
if resolver is None:
resolver = get_default_resolver()
if not name.is_absolute():
raise NotAbsolute(name)
while 1:
try:
answer = resolver.query(name, dns.rdatatype.SOA, rdclass, tcp)
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):
pass
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_ADDRCONFIG|socket.AI_V4MAPPED) != 0:
raise NotImplementedError
if host is None and service is None:
raise socket.gaierror(socket.EAI_NONAME)
v6addrs = []
v4addrs = []
canonical_name = None
try:
# Is host None or a V6 address literal?
if host is None:
canonical_name = 'localhost'
if flags & socket.AI_PASSIVE != 0:
v6addrs.append('::')
v4addrs.append('0.0.0.0')
else:
v6addrs.append('::1')
v4addrs.append('127.0.0.1')
else:
parts = host.split('%')
if len(parts) == 2:
ahost = parts[0]
else:
ahost = host
addr = dns.ipv6.inet_aton(ahost)
v6addrs.append(host)
canonical_name = host
except:
try:
# Is it a V4 address literal?
addr = dns.ipv4.inet_aton(host)
v4addrs.append(host)
canonical_name = host
except:
if flags & socket.AI_NUMERICHOST == 0:
try:
qname = None
if family == socket.AF_INET6 or family == socket.AF_UNSPEC:
v6 = _resolver.query(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.query(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)
except:
raise socket.gaierror(socket.EAI_SYSTEM)
port = None
try:
# Is it a port literal?
if service is None:
port = 0
else:
port = int(service)
except:
if flags & socket.AI_NUMERICSERV == 0:
try:
port = socket.getservbyname(service)
except:
pass
if port is None:
raise socket.gaierror(socket.EAI_NONAME)
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)
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.query(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)
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()
return _getnameinfo(_getaddrinfo(name, 80)[0][4])[0]
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:
addr = dns.ipv6.inet_aton(ip)
sockaddr = (ip, 80, 0, 0)
family = socket.AF_INET6
except:
sockaddr = (ip, 80)
family = socket.AF_INET
(name, port) = _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]
for item in tuples:
addresses.append(item[4][0])
# 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.
@param resolver: the resolver to use
@type resolver: dns.resolver.Resolver object or None
"""
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 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
|