Spaces:
Running
Running
File size: 65,993 Bytes
b72ab63 |
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 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298 1299 1300 1301 1302 1303 1304 1305 1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349 1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447 1448 1449 1450 1451 1452 1453 1454 1455 1456 1457 1458 1459 1460 1461 1462 1463 1464 1465 1466 1467 1468 1469 1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491 1492 1493 1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565 1566 1567 1568 1569 1570 1571 1572 1573 1574 1575 1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623 1624 1625 1626 1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661 1662 1663 1664 1665 1666 1667 1668 1669 1670 1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726 1727 1728 1729 1730 1731 1732 1733 1734 1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757 1758 1759 1760 1761 1762 1763 1764 1765 1766 1767 1768 1769 1770 1771 1772 1773 1774 1775 1776 1777 1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788 1789 1790 1791 1792 1793 1794 1795 1796 1797 1798 1799 1800 1801 1802 1803 1804 1805 1806 1807 1808 1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 1848 1849 1850 1851 1852 1853 1854 1855 1856 1857 1858 1859 1860 1861 1862 1863 1864 1865 1866 1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878 1879 1880 1881 1882 1883 1884 1885 1886 1887 1888 1889 |
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2001-2017 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""DNS Messages"""
import contextlib
import io
import time
from typing import Any, Dict, List, Optional, Tuple, Union
import dns.edns
import dns.entropy
import dns.enum
import dns.exception
import dns.flags
import dns.name
import dns.opcode
import dns.rcode
import dns.rdata
import dns.rdataclass
import dns.rdatatype
import dns.rdtypes.ANY.OPT
import dns.rdtypes.ANY.TSIG
import dns.renderer
import dns.rrset
import dns.tsig
import dns.ttl
import dns.wire
class ShortHeader(dns.exception.FormError):
"""The DNS packet passed to from_wire() is too short."""
class TrailingJunk(dns.exception.FormError):
"""The DNS packet passed to from_wire() has extra junk at the end of it."""
class UnknownHeaderField(dns.exception.DNSException):
"""The header field name was not recognized when converting from text
into a message."""
class BadEDNS(dns.exception.FormError):
"""An OPT record occurred somewhere other than
the additional data section."""
class BadTSIG(dns.exception.FormError):
"""A TSIG record occurred somewhere other than the end of
the additional data section."""
class UnknownTSIGKey(dns.exception.DNSException):
"""A TSIG with an unknown key was received."""
class Truncated(dns.exception.DNSException):
"""The truncated flag is set."""
supp_kwargs = {"message"}
# We do this as otherwise mypy complains about unexpected keyword argument
# idna_exception
def __init__(self, *args, **kwargs):
super().__init__(*args, **kwargs)
def message(self):
"""As much of the message as could be processed.
Returns a ``dns.message.Message``.
"""
return self.kwargs["message"]
class NotQueryResponse(dns.exception.DNSException):
"""Message is not a response to a query."""
class ChainTooLong(dns.exception.DNSException):
"""The CNAME chain is too long."""
class AnswerForNXDOMAIN(dns.exception.DNSException):
"""The rcode is NXDOMAIN but an answer was found."""
class NoPreviousName(dns.exception.SyntaxError):
"""No previous name was known."""
class MessageSection(dns.enum.IntEnum):
"""Message sections"""
QUESTION = 0
ANSWER = 1
AUTHORITY = 2
ADDITIONAL = 3
@classmethod
def _maximum(cls):
return 3
class MessageError:
def __init__(self, exception: Exception, offset: int):
self.exception = exception
self.offset = offset
DEFAULT_EDNS_PAYLOAD = 1232
MAX_CHAIN = 16
IndexKeyType = Tuple[
int,
dns.name.Name,
dns.rdataclass.RdataClass,
dns.rdatatype.RdataType,
Optional[dns.rdatatype.RdataType],
Optional[dns.rdataclass.RdataClass],
]
IndexType = Dict[IndexKeyType, dns.rrset.RRset]
SectionType = Union[int, str, List[dns.rrset.RRset]]
class Message:
"""A DNS message."""
_section_enum = MessageSection
def __init__(self, id: Optional[int] = None):
if id is None:
self.id = dns.entropy.random_16()
else:
self.id = id
self.flags = 0
self.sections: List[List[dns.rrset.RRset]] = [[], [], [], []]
self.opt: Optional[dns.rrset.RRset] = None
self.request_payload = 0
self.pad = 0
self.keyring: Any = None
self.tsig: Optional[dns.rrset.RRset] = None
self.request_mac = b""
self.xfr = False
self.origin: Optional[dns.name.Name] = None
self.tsig_ctx: Optional[Any] = None
self.index: IndexType = {}
self.errors: List[MessageError] = []
self.time = 0.0
@property
def question(self) -> List[dns.rrset.RRset]:
"""The question section."""
return self.sections[0]
@question.setter
def question(self, v):
self.sections[0] = v
@property
def answer(self) -> List[dns.rrset.RRset]:
"""The answer section."""
return self.sections[1]
@answer.setter
def answer(self, v):
self.sections[1] = v
@property
def authority(self) -> List[dns.rrset.RRset]:
"""The authority section."""
return self.sections[2]
@authority.setter
def authority(self, v):
self.sections[2] = v
@property
def additional(self) -> List[dns.rrset.RRset]:
"""The additional data section."""
return self.sections[3]
@additional.setter
def additional(self, v):
self.sections[3] = v
def __repr__(self):
return "<DNS message, ID " + repr(self.id) + ">"
def __str__(self):
return self.to_text()
def to_text(
self,
origin: Optional[dns.name.Name] = None,
relativize: bool = True,
**kw: Dict[str, Any],
) -> str:
"""Convert the message to text.
The *origin*, *relativize*, and any other keyword
arguments are passed to the RRset ``to_wire()`` method.
Returns a ``str``.
"""
s = io.StringIO()
s.write("id %d\n" % self.id)
s.write("opcode %s\n" % dns.opcode.to_text(self.opcode()))
s.write("rcode %s\n" % dns.rcode.to_text(self.rcode()))
s.write("flags %s\n" % dns.flags.to_text(self.flags))
if self.edns >= 0:
s.write("edns %s\n" % self.edns)
if self.ednsflags != 0:
s.write("eflags %s\n" % dns.flags.edns_to_text(self.ednsflags))
s.write("payload %d\n" % self.payload)
for opt in self.options:
s.write("option %s\n" % opt.to_text())
for name, which in self._section_enum.__members__.items():
s.write(f";{name}\n")
for rrset in self.section_from_number(which):
s.write(rrset.to_text(origin, relativize, **kw))
s.write("\n")
#
# We strip off the final \n so the caller can print the result without
# doing weird things to get around eccentricities in Python print
# formatting
#
return s.getvalue()[:-1]
def __eq__(self, other):
"""Two messages are equal if they have the same content in the
header, question, answer, and authority sections.
Returns a ``bool``.
"""
if not isinstance(other, Message):
return False
if self.id != other.id:
return False
if self.flags != other.flags:
return False
for i, section in enumerate(self.sections):
other_section = other.sections[i]
for n in section:
if n not in other_section:
return False
for n in other_section:
if n not in section:
return False
return True
def __ne__(self, other):
return not self.__eq__(other)
def is_response(self, other: "Message") -> bool:
"""Is *other*, also a ``dns.message.Message``, a response to this
message?
Returns a ``bool``.
"""
if (
other.flags & dns.flags.QR == 0
or self.id != other.id
or dns.opcode.from_flags(self.flags) != dns.opcode.from_flags(other.flags)
):
return False
if other.rcode() in {
dns.rcode.FORMERR,
dns.rcode.SERVFAIL,
dns.rcode.NOTIMP,
dns.rcode.REFUSED,
}:
# We don't check the question section in these cases if
# the other question section is empty, even though they
# still really ought to have a question section.
if len(other.question) == 0:
return True
if dns.opcode.is_update(self.flags):
# This is assuming the "sender doesn't include anything
# from the update", but we don't care to check the other
# case, which is that all the sections are returned and
# identical.
return True
for n in self.question:
if n not in other.question:
return False
for n in other.question:
if n not in self.question:
return False
return True
def section_number(self, section: List[dns.rrset.RRset]) -> int:
"""Return the "section number" of the specified section for use
in indexing.
*section* is one of the section attributes of this message.
Raises ``ValueError`` if the section isn't known.
Returns an ``int``.
"""
for i, our_section in enumerate(self.sections):
if section is our_section:
return self._section_enum(i)
raise ValueError("unknown section")
def section_from_number(self, number: int) -> List[dns.rrset.RRset]:
"""Return the section list associated with the specified section
number.
*number* is a section number `int` or the text form of a section
name.
Raises ``ValueError`` if the section isn't known.
Returns a ``list``.
"""
section = self._section_enum.make(number)
return self.sections[section]
def find_rrset(
self,
section: SectionType,
name: dns.name.Name,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType = dns.rdatatype.NONE,
deleting: Optional[dns.rdataclass.RdataClass] = None,
create: bool = False,
force_unique: bool = False,
idna_codec: Optional[dns.name.IDNACodec] = None,
) -> dns.rrset.RRset:
"""Find the RRset with the given attributes in the specified section.
*section*, an ``int`` section number, a ``str`` section name, or one of
the section attributes of this message. This specifies the
the section of the message to search. For example::
my_message.find_rrset(my_message.answer, name, rdclass, rdtype)
my_message.find_rrset(dns.message.ANSWER, name, rdclass, rdtype)
my_message.find_rrset("ANSWER", name, rdclass, rdtype)
*name*, a ``dns.name.Name`` or ``str``, the name of the RRset.
*rdclass*, an ``int`` or ``str``, the class of the RRset.
*rdtype*, an ``int`` or ``str``, the type of the RRset.
*covers*, an ``int`` or ``str``, the covers value of the RRset.
The default is ``dns.rdatatype.NONE``.
*deleting*, an ``int``, ``str``, or ``None``, the deleting value of the
RRset. The default is ``None``.
*create*, a ``bool``. If ``True``, create the RRset if it is not found.
The created RRset is appended to *section*.
*force_unique*, a ``bool``. If ``True`` and *create* is also ``True``,
create a new RRset regardless of whether a matching RRset exists
already. The default is ``False``. This is useful when creating
DDNS Update messages, as order matters for them.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder
is used.
Raises ``KeyError`` if the RRset was not found and create was
``False``.
Returns a ``dns.rrset.RRset object``.
"""
if isinstance(section, int):
section_number = section
section = self.section_from_number(section_number)
elif isinstance(section, str):
section_number = self._section_enum.from_text(section)
section = self.section_from_number(section_number)
else:
section_number = self.section_number(section)
if isinstance(name, str):
name = dns.name.from_text(name, idna_codec=idna_codec)
rdtype = dns.rdatatype.RdataType.make(rdtype)
rdclass = dns.rdataclass.RdataClass.make(rdclass)
covers = dns.rdatatype.RdataType.make(covers)
if deleting is not None:
deleting = dns.rdataclass.RdataClass.make(deleting)
key = (section_number, name, rdclass, rdtype, covers, deleting)
if not force_unique:
if self.index is not None:
rrset = self.index.get(key)
if rrset is not None:
return rrset
else:
for rrset in section:
if rrset.full_match(name, rdclass, rdtype, covers, deleting):
return rrset
if not create:
raise KeyError
rrset = dns.rrset.RRset(name, rdclass, rdtype, covers, deleting)
section.append(rrset)
if self.index is not None:
self.index[key] = rrset
return rrset
def get_rrset(
self,
section: SectionType,
name: dns.name.Name,
rdclass: dns.rdataclass.RdataClass,
rdtype: dns.rdatatype.RdataType,
covers: dns.rdatatype.RdataType = dns.rdatatype.NONE,
deleting: Optional[dns.rdataclass.RdataClass] = None,
create: bool = False,
force_unique: bool = False,
idna_codec: Optional[dns.name.IDNACodec] = None,
) -> Optional[dns.rrset.RRset]:
"""Get the RRset with the given attributes in the specified section.
If the RRset is not found, None is returned.
*section*, an ``int`` section number, a ``str`` section name, or one of
the section attributes of this message. This specifies the
the section of the message to search. For example::
my_message.get_rrset(my_message.answer, name, rdclass, rdtype)
my_message.get_rrset(dns.message.ANSWER, name, rdclass, rdtype)
my_message.get_rrset("ANSWER", name, rdclass, rdtype)
*name*, a ``dns.name.Name`` or ``str``, the name of the RRset.
*rdclass*, an ``int`` or ``str``, the class of the RRset.
*rdtype*, an ``int`` or ``str``, the type of the RRset.
*covers*, an ``int`` or ``str``, the covers value of the RRset.
The default is ``dns.rdatatype.NONE``.
*deleting*, an ``int``, ``str``, or ``None``, the deleting value of the
RRset. The default is ``None``.
*create*, a ``bool``. If ``True``, create the RRset if it is not found.
The created RRset is appended to *section*.
*force_unique*, a ``bool``. If ``True`` and *create* is also ``True``,
create a new RRset regardless of whether a matching RRset exists
already. The default is ``False``. This is useful when creating
DDNS Update messages, as order matters for them.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder
is used.
Returns a ``dns.rrset.RRset object`` or ``None``.
"""
try:
rrset = self.find_rrset(
section,
name,
rdclass,
rdtype,
covers,
deleting,
create,
force_unique,
idna_codec,
)
except KeyError:
rrset = None
return rrset
def section_count(self, section: SectionType) -> int:
"""Returns the number of records in the specified section.
*section*, an ``int`` section number, a ``str`` section name, or one of
the section attributes of this message. This specifies the
the section of the message to count. For example::
my_message.section_count(my_message.answer)
my_message.section_count(dns.message.ANSWER)
my_message.section_count("ANSWER")
"""
if isinstance(section, int):
section_number = section
section = self.section_from_number(section_number)
elif isinstance(section, str):
section_number = self._section_enum.from_text(section)
section = self.section_from_number(section_number)
else:
section_number = self.section_number(section)
count = sum(max(1, len(rrs)) for rrs in section)
if section_number == MessageSection.ADDITIONAL:
if self.opt is not None:
count += 1
if self.tsig is not None:
count += 1
return count
def _compute_opt_reserve(self) -> int:
"""Compute the size required for the OPT RR, padding excluded"""
if not self.opt:
return 0
# 1 byte for the root name, 10 for the standard RR fields
size = 11
# This would be more efficient if options had a size() method, but we won't
# worry about that for now. We also don't worry if there is an existing padding
# option, as it is unlikely and probably harmless, as the worst case is that we
# may add another, and this seems to be legal.
for option in self.opt[0].options:
wire = option.to_wire()
# We add 4 here to account for the option type and length
size += len(wire) + 4
if self.pad:
# Padding will be added, so again add the option type and length.
size += 4
return size
def _compute_tsig_reserve(self) -> int:
"""Compute the size required for the TSIG RR"""
# This would be more efficient if TSIGs had a size method, but we won't
# worry about for now. Also, we can't really cope with the potential
# compressibility of the TSIG owner name, so we estimate with the uncompressed
# size. We will disable compression when TSIG and padding are both is active
# so that the padding comes out right.
if not self.tsig:
return 0
f = io.BytesIO()
self.tsig.to_wire(f)
return len(f.getvalue())
def to_wire(
self,
origin: Optional[dns.name.Name] = None,
max_size: int = 0,
multi: bool = False,
tsig_ctx: Optional[Any] = None,
prepend_length: bool = False,
prefer_truncation: bool = False,
**kw: Dict[str, Any],
) -> bytes:
"""Return a string containing the message in DNS compressed wire
format.
Additional keyword arguments are passed to the RRset ``to_wire()``
method.
*origin*, a ``dns.name.Name`` or ``None``, the origin to be appended
to any relative names. If ``None``, and the message has an origin
attribute that is not ``None``, then it will be used.
*max_size*, an ``int``, the maximum size of the wire format
output; default is 0, which means "the message's request
payload, if nonzero, or 65535".
*multi*, a ``bool``, should be set to ``True`` if this message is
part of a multiple message sequence.
*tsig_ctx*, a ``dns.tsig.HMACTSig`` or ``dns.tsig.GSSTSig`` object, the
ongoing TSIG context, used when signing zone transfers.
*prepend_length*, a ``bool``, should be set to ``True`` if the caller
wants the message length prepended to the message itself. This is
useful for messages sent over TCP, TLS (DoT), or QUIC (DoQ).
*prefer_truncation*, a ``bool``, should be set to ``True`` if the caller
wants the message to be truncated if it would otherwise exceed the
maximum length. If the truncation occurs before the additional section,
the TC bit will be set.
Raises ``dns.exception.TooBig`` if *max_size* was exceeded.
Returns a ``bytes``.
"""
if origin is None and self.origin is not None:
origin = self.origin
if max_size == 0:
if self.request_payload != 0:
max_size = self.request_payload
else:
max_size = 65535
if max_size < 512:
max_size = 512
elif max_size > 65535:
max_size = 65535
r = dns.renderer.Renderer(self.id, self.flags, max_size, origin)
opt_reserve = self._compute_opt_reserve()
r.reserve(opt_reserve)
tsig_reserve = self._compute_tsig_reserve()
r.reserve(tsig_reserve)
try:
for rrset in self.question:
r.add_question(rrset.name, rrset.rdtype, rrset.rdclass)
for rrset in self.answer:
r.add_rrset(dns.renderer.ANSWER, rrset, **kw)
for rrset in self.authority:
r.add_rrset(dns.renderer.AUTHORITY, rrset, **kw)
for rrset in self.additional:
r.add_rrset(dns.renderer.ADDITIONAL, rrset, **kw)
except dns.exception.TooBig:
if prefer_truncation:
if r.section < dns.renderer.ADDITIONAL:
r.flags |= dns.flags.TC
else:
raise
r.release_reserved()
if self.opt is not None:
r.add_opt(self.opt, self.pad, opt_reserve, tsig_reserve)
r.write_header()
if self.tsig is not None:
(new_tsig, ctx) = dns.tsig.sign(
r.get_wire(),
self.keyring,
self.tsig[0],
int(time.time()),
self.request_mac,
tsig_ctx,
multi,
)
self.tsig.clear()
self.tsig.add(new_tsig)
r.add_rrset(dns.renderer.ADDITIONAL, self.tsig)
r.write_header()
if multi:
self.tsig_ctx = ctx
wire = r.get_wire()
if prepend_length:
wire = len(wire).to_bytes(2, "big") + wire
return wire
@staticmethod
def _make_tsig(
keyname, algorithm, time_signed, fudge, mac, original_id, error, other
):
tsig = dns.rdtypes.ANY.TSIG.TSIG(
dns.rdataclass.ANY,
dns.rdatatype.TSIG,
algorithm,
time_signed,
fudge,
mac,
original_id,
error,
other,
)
return dns.rrset.from_rdata(keyname, 0, tsig)
def use_tsig(
self,
keyring: Any,
keyname: Optional[Union[dns.name.Name, str]] = None,
fudge: int = 300,
original_id: Optional[int] = None,
tsig_error: int = 0,
other_data: bytes = b"",
algorithm: Union[dns.name.Name, str] = dns.tsig.default_algorithm,
) -> None:
"""When sending, a TSIG signature using the specified key
should be added.
*key*, a ``dns.tsig.Key`` is the key to use. If a key is specified,
the *keyring* and *algorithm* fields are not used.
*keyring*, a ``dict``, ``callable`` or ``dns.tsig.Key``, is either
the TSIG keyring or key to use.
The format of a keyring dict is a mapping from TSIG key name, as
``dns.name.Name`` to ``dns.tsig.Key`` or a TSIG secret, a ``bytes``.
If a ``dict`` *keyring* is specified but a *keyname* is not, 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 ``dict`` keyring is used, unless they know the keyring
contains only one key. If a ``callable`` keyring is specified, the
callable will be called with the message and the keyname, and is
expected to return a key.
*keyname*, a ``dns.name.Name``, ``str`` or ``None``, the name of
this TSIG key to use; defaults to ``None``. If *keyring* is a
``dict``, the key must be defined in it. If *keyring* is a
``dns.tsig.Key``, this is ignored.
*fudge*, an ``int``, the TSIG time fudge.
*original_id*, an ``int``, the TSIG original id. If ``None``,
the message's id is used.
*tsig_error*, an ``int``, the TSIG error code.
*other_data*, a ``bytes``, the TSIG other data.
*algorithm*, a ``dns.name.Name`` or ``str``, the TSIG algorithm to use. This is
only used if *keyring* is a ``dict``, and the key entry is a ``bytes``.
"""
if isinstance(keyring, dns.tsig.Key):
key = keyring
keyname = key.name
elif callable(keyring):
key = keyring(self, keyname)
else:
if isinstance(keyname, str):
keyname = dns.name.from_text(keyname)
if keyname is None:
keyname = next(iter(keyring))
key = keyring[keyname]
if isinstance(key, bytes):
key = dns.tsig.Key(keyname, key, algorithm)
self.keyring = key
if original_id is None:
original_id = self.id
self.tsig = self._make_tsig(
keyname,
self.keyring.algorithm,
0,
fudge,
b"\x00" * dns.tsig.mac_sizes[self.keyring.algorithm],
original_id,
tsig_error,
other_data,
)
@property
def keyname(self) -> Optional[dns.name.Name]:
if self.tsig:
return self.tsig.name
else:
return None
@property
def keyalgorithm(self) -> Optional[dns.name.Name]:
if self.tsig:
return self.tsig[0].algorithm
else:
return None
@property
def mac(self) -> Optional[bytes]:
if self.tsig:
return self.tsig[0].mac
else:
return None
@property
def tsig_error(self) -> Optional[int]:
if self.tsig:
return self.tsig[0].error
else:
return None
@property
def had_tsig(self) -> bool:
return bool(self.tsig)
@staticmethod
def _make_opt(flags=0, payload=DEFAULT_EDNS_PAYLOAD, options=None):
opt = dns.rdtypes.ANY.OPT.OPT(payload, dns.rdatatype.OPT, options or ())
return dns.rrset.from_rdata(dns.name.root, int(flags), opt)
def use_edns(
self,
edns: Optional[Union[int, bool]] = 0,
ednsflags: int = 0,
payload: int = DEFAULT_EDNS_PAYLOAD,
request_payload: Optional[int] = None,
options: Optional[List[dns.edns.Option]] = None,
pad: int = 0,
) -> None:
"""Configure EDNS behavior.
*edns*, an ``int``, is the EDNS level to use. Specifying ``None``, ``False``,
or ``-1`` means "do not use EDNS", and in this case the other parameters are
ignored. Specifying ``True`` is equivalent to specifying 0, i.e. "use EDNS0".
*ednsflags*, an ``int``, the EDNS flag values.
*payload*, an ``int``, is the EDNS sender's payload field, which is the maximum
size of UDP datagram the sender can handle. I.e. how big a response to this
message can be.
*request_payload*, an ``int``, is the EDNS payload size to use when sending this
message. If not specified, defaults to the value of *payload*.
*options*, a list of ``dns.edns.Option`` objects or ``None``, the EDNS options.
*pad*, a non-negative ``int``. If 0, the default, do not pad; otherwise add
padding bytes to make the message size a multiple of *pad*. Note that if
padding is non-zero, an EDNS PADDING option will always be added to the
message.
"""
if edns is None or edns is False:
edns = -1
elif edns is True:
edns = 0
if edns < 0:
self.opt = None
self.request_payload = 0
else:
# make sure the EDNS version in ednsflags agrees with edns
ednsflags &= 0xFF00FFFF
ednsflags |= edns << 16
if options is None:
options = []
self.opt = self._make_opt(ednsflags, payload, options)
if request_payload is None:
request_payload = payload
self.request_payload = request_payload
if pad < 0:
raise ValueError("pad must be non-negative")
self.pad = pad
@property
def edns(self) -> int:
if self.opt:
return (self.ednsflags & 0xFF0000) >> 16
else:
return -1
@property
def ednsflags(self) -> int:
if self.opt:
return self.opt.ttl
else:
return 0
@ednsflags.setter
def ednsflags(self, v):
if self.opt:
self.opt.ttl = v
elif v:
self.opt = self._make_opt(v)
@property
def payload(self) -> int:
if self.opt:
return self.opt[0].payload
else:
return 0
@property
def options(self) -> Tuple:
if self.opt:
return self.opt[0].options
else:
return ()
def want_dnssec(self, wanted: bool = True) -> None:
"""Enable or disable 'DNSSEC desired' flag in requests.
*wanted*, a ``bool``. If ``True``, then DNSSEC data is
desired in the response, EDNS is enabled if required, and then
the DO bit is set. If ``False``, the DO bit is cleared if
EDNS is enabled.
"""
if wanted:
self.ednsflags |= dns.flags.DO
elif self.opt:
self.ednsflags &= ~int(dns.flags.DO)
def rcode(self) -> dns.rcode.Rcode:
"""Return the rcode.
Returns a ``dns.rcode.Rcode``.
"""
return dns.rcode.from_flags(int(self.flags), int(self.ednsflags))
def set_rcode(self, rcode: dns.rcode.Rcode) -> None:
"""Set the rcode.
*rcode*, a ``dns.rcode.Rcode``, is the rcode to set.
"""
(value, evalue) = dns.rcode.to_flags(rcode)
self.flags &= 0xFFF0
self.flags |= value
self.ednsflags &= 0x00FFFFFF
self.ednsflags |= evalue
def opcode(self) -> dns.opcode.Opcode:
"""Return the opcode.
Returns a ``dns.opcode.Opcode``.
"""
return dns.opcode.from_flags(int(self.flags))
def set_opcode(self, opcode: dns.opcode.Opcode) -> None:
"""Set the opcode.
*opcode*, a ``dns.opcode.Opcode``, is the opcode to set.
"""
self.flags &= 0x87FF
self.flags |= dns.opcode.to_flags(opcode)
def _get_one_rr_per_rrset(self, value):
# What the caller picked is fine.
return value
# pylint: disable=unused-argument
def _parse_rr_header(self, section, name, rdclass, rdtype):
return (rdclass, rdtype, None, False)
# pylint: enable=unused-argument
def _parse_special_rr_header(self, section, count, position, name, rdclass, rdtype):
if rdtype == dns.rdatatype.OPT:
if (
section != MessageSection.ADDITIONAL
or self.opt
or name != dns.name.root
):
raise BadEDNS
elif rdtype == dns.rdatatype.TSIG:
if (
section != MessageSection.ADDITIONAL
or rdclass != dns.rdatatype.ANY
or position != count - 1
):
raise BadTSIG
return (rdclass, rdtype, None, False)
class ChainingResult:
"""The result of a call to dns.message.QueryMessage.resolve_chaining().
The ``answer`` attribute is the answer RRSet, or ``None`` if it doesn't
exist.
The ``canonical_name`` attribute is the canonical name after all
chaining has been applied (this is the same name as ``rrset.name`` in cases
where rrset is not ``None``).
The ``minimum_ttl`` attribute is the minimum TTL, i.e. the TTL to
use if caching the data. It is the smallest of all the CNAME TTLs
and either the answer TTL if it exists or the SOA TTL and SOA
minimum values for negative answers.
The ``cnames`` attribute is a list of all the CNAME RRSets followed to
get to the canonical name.
"""
def __init__(
self,
canonical_name: dns.name.Name,
answer: Optional[dns.rrset.RRset],
minimum_ttl: int,
cnames: List[dns.rrset.RRset],
):
self.canonical_name = canonical_name
self.answer = answer
self.minimum_ttl = minimum_ttl
self.cnames = cnames
class QueryMessage(Message):
def resolve_chaining(self) -> ChainingResult:
"""Follow the CNAME chain in the response to determine the answer
RRset.
Raises ``dns.message.NotQueryResponse`` if the message is not
a response.
Raises ``dns.message.ChainTooLong`` if the CNAME chain is too long.
Raises ``dns.message.AnswerForNXDOMAIN`` if the rcode is NXDOMAIN
but an answer was found.
Raises ``dns.exception.FormError`` if the question count is not 1.
Returns a ChainingResult object.
"""
if self.flags & dns.flags.QR == 0:
raise NotQueryResponse
if len(self.question) != 1:
raise dns.exception.FormError
question = self.question[0]
qname = question.name
min_ttl = dns.ttl.MAX_TTL
answer = None
count = 0
cnames = []
while count < MAX_CHAIN:
try:
answer = self.find_rrset(
self.answer, qname, question.rdclass, question.rdtype
)
min_ttl = min(min_ttl, answer.ttl)
break
except KeyError:
if question.rdtype != dns.rdatatype.CNAME:
try:
crrset = self.find_rrset(
self.answer, qname, question.rdclass, dns.rdatatype.CNAME
)
cnames.append(crrset)
min_ttl = min(min_ttl, crrset.ttl)
for rd in crrset:
qname = rd.target
break
count += 1
continue
except KeyError:
# Exit the chaining loop
break
else:
# Exit the chaining loop
break
if count >= MAX_CHAIN:
raise ChainTooLong
if self.rcode() == dns.rcode.NXDOMAIN and answer is not None:
raise AnswerForNXDOMAIN
if answer is None:
# Further minimize the TTL with NCACHE.
auname = qname
while True:
# Look for an SOA RR whose owner name is a superdomain
# of qname.
try:
srrset = self.find_rrset(
self.authority, auname, question.rdclass, dns.rdatatype.SOA
)
min_ttl = min(min_ttl, srrset.ttl, srrset[0].minimum)
break
except KeyError:
try:
auname = auname.parent()
except dns.name.NoParent:
break
return ChainingResult(qname, answer, min_ttl, cnames)
def canonical_name(self) -> dns.name.Name:
"""Return the canonical name of the first name in the question
section.
Raises ``dns.message.NotQueryResponse`` if the message is not
a response.
Raises ``dns.message.ChainTooLong`` if the CNAME chain is too long.
Raises ``dns.message.AnswerForNXDOMAIN`` if the rcode is NXDOMAIN
but an answer was found.
Raises ``dns.exception.FormError`` if the question count is not 1.
"""
return self.resolve_chaining().canonical_name
def _maybe_import_update():
# We avoid circular imports by doing this here. We do it in another
# function as doing it in _message_factory_from_opcode() makes "dns"
# a local symbol, and the first line fails :)
# pylint: disable=redefined-outer-name,import-outside-toplevel,unused-import
import dns.update # noqa: F401
def _message_factory_from_opcode(opcode):
if opcode == dns.opcode.QUERY:
return QueryMessage
elif opcode == dns.opcode.UPDATE:
_maybe_import_update()
return dns.update.UpdateMessage
else:
return Message
class _WireReader:
"""Wire format reader.
parser: the binary parser
message: The message object being built
initialize_message: Callback to set message parsing options
question_only: Are we only reading the question?
one_rr_per_rrset: Put each RR into its own RRset?
keyring: TSIG keyring
ignore_trailing: Ignore trailing junk at end of request?
multi: Is this message part of a multi-message sequence?
DNS dynamic updates.
continue_on_error: try to extract as much information as possible from
the message, accumulating MessageErrors in the *errors* attribute instead of
raising them.
"""
def __init__(
self,
wire,
initialize_message,
question_only=False,
one_rr_per_rrset=False,
ignore_trailing=False,
keyring=None,
multi=False,
continue_on_error=False,
):
self.parser = dns.wire.Parser(wire)
self.message = None
self.initialize_message = initialize_message
self.question_only = question_only
self.one_rr_per_rrset = one_rr_per_rrset
self.ignore_trailing = ignore_trailing
self.keyring = keyring
self.multi = multi
self.continue_on_error = continue_on_error
self.errors = []
def _get_question(self, section_number, qcount):
"""Read the next *qcount* records from the wire data and add them to
the question section.
"""
assert self.message is not None
section = self.message.sections[section_number]
for _ in range(qcount):
qname = self.parser.get_name(self.message.origin)
(rdtype, rdclass) = self.parser.get_struct("!HH")
(rdclass, rdtype, _, _) = self.message._parse_rr_header(
section_number, qname, rdclass, rdtype
)
self.message.find_rrset(
section, qname, rdclass, rdtype, create=True, force_unique=True
)
def _add_error(self, e):
self.errors.append(MessageError(e, self.parser.current))
def _get_section(self, section_number, count):
"""Read the next I{count} records from the wire data and add them to
the specified section.
section_number: the section of the message to which to add records
count: the number of records to read
"""
assert self.message is not None
section = self.message.sections[section_number]
force_unique = self.one_rr_per_rrset
for i in range(count):
rr_start = self.parser.current
absolute_name = self.parser.get_name()
if self.message.origin is not None:
name = absolute_name.relativize(self.message.origin)
else:
name = absolute_name
(rdtype, rdclass, ttl, rdlen) = self.parser.get_struct("!HHIH")
if rdtype in (dns.rdatatype.OPT, dns.rdatatype.TSIG):
(
rdclass,
rdtype,
deleting,
empty,
) = self.message._parse_special_rr_header(
section_number, count, i, name, rdclass, rdtype
)
else:
(rdclass, rdtype, deleting, empty) = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
rdata_start = self.parser.current
try:
if empty:
if rdlen > 0:
raise dns.exception.FormError
rd = None
covers = dns.rdatatype.NONE
else:
with self.parser.restrict_to(rdlen):
rd = dns.rdata.from_wire_parser(
rdclass, rdtype, self.parser, self.message.origin
)
covers = rd.covers()
if self.message.xfr and rdtype == dns.rdatatype.SOA:
force_unique = True
if rdtype == dns.rdatatype.OPT:
self.message.opt = dns.rrset.from_rdata(name, ttl, rd)
elif rdtype == dns.rdatatype.TSIG:
if self.keyring is None:
raise UnknownTSIGKey("got signed message without keyring")
if isinstance(self.keyring, dict):
key = self.keyring.get(absolute_name)
if isinstance(key, bytes):
key = dns.tsig.Key(absolute_name, key, rd.algorithm)
elif callable(self.keyring):
key = self.keyring(self.message, absolute_name)
else:
key = self.keyring
if key is None:
raise UnknownTSIGKey("key '%s' unknown" % name)
self.message.keyring = key
self.message.tsig_ctx = dns.tsig.validate(
self.parser.wire,
key,
absolute_name,
rd,
int(time.time()),
self.message.request_mac,
rr_start,
self.message.tsig_ctx,
self.multi,
)
self.message.tsig = dns.rrset.from_rdata(absolute_name, 0, rd)
else:
rrset = self.message.find_rrset(
section,
name,
rdclass,
rdtype,
covers,
deleting,
True,
force_unique,
)
if rd is not None:
if ttl > 0x7FFFFFFF:
ttl = 0
rrset.add(rd, ttl)
except Exception as e:
if self.continue_on_error:
self._add_error(e)
self.parser.seek(rdata_start + rdlen)
else:
raise
def read(self):
"""Read a wire format DNS message and build a dns.message.Message
object."""
if self.parser.remaining() < 12:
raise ShortHeader
(id, flags, qcount, ancount, aucount, adcount) = self.parser.get_struct(
"!HHHHHH"
)
factory = _message_factory_from_opcode(dns.opcode.from_flags(flags))
self.message = factory(id=id)
self.message.flags = dns.flags.Flag(flags)
self.initialize_message(self.message)
self.one_rr_per_rrset = self.message._get_one_rr_per_rrset(
self.one_rr_per_rrset
)
try:
self._get_question(MessageSection.QUESTION, qcount)
if self.question_only:
return self.message
self._get_section(MessageSection.ANSWER, ancount)
self._get_section(MessageSection.AUTHORITY, aucount)
self._get_section(MessageSection.ADDITIONAL, adcount)
if not self.ignore_trailing and self.parser.remaining() != 0:
raise TrailingJunk
if self.multi and self.message.tsig_ctx and not self.message.had_tsig:
self.message.tsig_ctx.update(self.parser.wire)
except Exception as e:
if self.continue_on_error:
self._add_error(e)
else:
raise
return self.message
def from_wire(
wire: bytes,
keyring: Optional[Any] = None,
request_mac: Optional[bytes] = b"",
xfr: bool = False,
origin: Optional[dns.name.Name] = None,
tsig_ctx: Optional[Union[dns.tsig.HMACTSig, dns.tsig.GSSTSig]] = None,
multi: bool = False,
question_only: bool = False,
one_rr_per_rrset: bool = False,
ignore_trailing: bool = False,
raise_on_truncation: bool = False,
continue_on_error: bool = False,
) -> Message:
"""Convert a DNS wire format message into a message object.
*keyring*, a ``dns.tsig.Key`` or ``dict``, the key or keyring to use if the message
is signed.
*request_mac*, a ``bytes`` or ``None``. If the message is a response to a
TSIG-signed request, *request_mac* should be set to the MAC of that request.
*xfr*, a ``bool``, should be set to ``True`` if this message is part of a zone
transfer.
*origin*, a ``dns.name.Name`` or ``None``. If the message is part of a zone
transfer, *origin* should be the origin name of the zone. If not ``None``, names
will be relativized to the origin.
*tsig_ctx*, a ``dns.tsig.HMACTSig`` or ``dns.tsig.GSSTSig`` object, the ongoing TSIG
context, used when validating zone transfers.
*multi*, a ``bool``, should be set to ``True`` if this message is part of a multiple
message sequence.
*question_only*, a ``bool``. If ``True``, read only up to the end of the question
section.
*one_rr_per_rrset*, a ``bool``. If ``True``, put each RR into its own RRset.
*ignore_trailing*, a ``bool``. If ``True``, ignore trailing junk at end of the
message.
*raise_on_truncation*, a ``bool``. If ``True``, raise an exception if the TC bit is
set.
*continue_on_error*, a ``bool``. If ``True``, try to continue parsing even if
errors occur. Erroneous rdata will be ignored. Errors will be accumulated as a
list of MessageError objects in the message's ``errors`` attribute. This option is
recommended only for DNS analysis tools, or for use in a server as part of an error
handling path. The default is ``False``.
Raises ``dns.message.ShortHeader`` if the message is less than 12 octets long.
Raises ``dns.message.TrailingJunk`` if there were octets in the message past the end
of the proper DNS message, and *ignore_trailing* is ``False``.
Raises ``dns.message.BadEDNS`` if an OPT record was in the wrong section, or
occurred more than once.
Raises ``dns.message.BadTSIG`` if a TSIG record was not the last record of the
additional data section.
Raises ``dns.message.Truncated`` if the TC flag is set and *raise_on_truncation* is
``True``.
Returns a ``dns.message.Message``.
"""
# We permit None for request_mac solely for backwards compatibility
if request_mac is None:
request_mac = b""
def initialize_message(message):
message.request_mac = request_mac
message.xfr = xfr
message.origin = origin
message.tsig_ctx = tsig_ctx
reader = _WireReader(
wire,
initialize_message,
question_only,
one_rr_per_rrset,
ignore_trailing,
keyring,
multi,
continue_on_error,
)
try:
m = reader.read()
except dns.exception.FormError:
if (
reader.message
and (reader.message.flags & dns.flags.TC)
and raise_on_truncation
):
raise Truncated(message=reader.message)
else:
raise
# Reading a truncated message might not have any errors, so we
# have to do this check here too.
if m.flags & dns.flags.TC and raise_on_truncation:
raise Truncated(message=m)
if continue_on_error:
m.errors = reader.errors
return m
class _TextReader:
"""Text format reader.
tok: the tokenizer.
message: The message object being built.
DNS dynamic updates.
last_name: The most recently read name when building a message object.
one_rr_per_rrset: Put each RR into its own RRset?
origin: The origin for relative names
relativize: relativize names?
relativize_to: the origin to relativize to.
"""
def __init__(
self,
text,
idna_codec,
one_rr_per_rrset=False,
origin=None,
relativize=True,
relativize_to=None,
):
self.message = None
self.tok = dns.tokenizer.Tokenizer(text, idna_codec=idna_codec)
self.last_name = None
self.one_rr_per_rrset = one_rr_per_rrset
self.origin = origin
self.relativize = relativize
self.relativize_to = relativize_to
self.id = None
self.edns = -1
self.ednsflags = 0
self.payload = DEFAULT_EDNS_PAYLOAD
self.rcode = None
self.opcode = dns.opcode.QUERY
self.flags = 0
def _header_line(self, _):
"""Process one line from the text format header section."""
token = self.tok.get()
what = token.value
if what == "id":
self.id = self.tok.get_int()
elif what == "flags":
while True:
token = self.tok.get()
if not token.is_identifier():
self.tok.unget(token)
break
self.flags = self.flags | dns.flags.from_text(token.value)
elif what == "edns":
self.edns = self.tok.get_int()
self.ednsflags = self.ednsflags | (self.edns << 16)
elif what == "eflags":
if self.edns < 0:
self.edns = 0
while True:
token = self.tok.get()
if not token.is_identifier():
self.tok.unget(token)
break
self.ednsflags = self.ednsflags | dns.flags.edns_from_text(token.value)
elif what == "payload":
self.payload = self.tok.get_int()
if self.edns < 0:
self.edns = 0
elif what == "opcode":
text = self.tok.get_string()
self.opcode = dns.opcode.from_text(text)
self.flags = self.flags | dns.opcode.to_flags(self.opcode)
elif what == "rcode":
text = self.tok.get_string()
self.rcode = dns.rcode.from_text(text)
else:
raise UnknownHeaderField
self.tok.get_eol()
def _question_line(self, section_number):
"""Process one line from the text format question section."""
section = self.message.sections[section_number]
token = self.tok.get(want_leading=True)
if not token.is_whitespace():
self.last_name = self.tok.as_name(
token, self.message.origin, self.relativize, self.relativize_to
)
name = self.last_name
if name is None:
raise NoPreviousName
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
# Class
try:
rdclass = dns.rdataclass.from_text(token.value)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
rdclass = dns.rdataclass.IN
# Type
rdtype = dns.rdatatype.from_text(token.value)
(rdclass, rdtype, _, _) = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
self.message.find_rrset(
section, name, rdclass, rdtype, create=True, force_unique=True
)
self.tok.get_eol()
def _rr_line(self, section_number):
"""Process one line from the text format answer, authority, or
additional data sections.
"""
section = self.message.sections[section_number]
# Name
token = self.tok.get(want_leading=True)
if not token.is_whitespace():
self.last_name = self.tok.as_name(
token, self.message.origin, self.relativize, self.relativize_to
)
name = self.last_name
if name is None:
raise NoPreviousName
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
# TTL
try:
ttl = int(token.value, 0)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
ttl = 0
# Class
try:
rdclass = dns.rdataclass.from_text(token.value)
token = self.tok.get()
if not token.is_identifier():
raise dns.exception.SyntaxError
except dns.exception.SyntaxError:
raise dns.exception.SyntaxError
except Exception:
rdclass = dns.rdataclass.IN
# Type
rdtype = dns.rdatatype.from_text(token.value)
(rdclass, rdtype, deleting, empty) = self.message._parse_rr_header(
section_number, name, rdclass, rdtype
)
token = self.tok.get()
if empty and not token.is_eol_or_eof():
raise dns.exception.SyntaxError
if not empty and token.is_eol_or_eof():
raise dns.exception.UnexpectedEnd
if not token.is_eol_or_eof():
self.tok.unget(token)
rd = dns.rdata.from_text(
rdclass,
rdtype,
self.tok,
self.message.origin,
self.relativize,
self.relativize_to,
)
covers = rd.covers()
else:
rd = None
covers = dns.rdatatype.NONE
rrset = self.message.find_rrset(
section,
name,
rdclass,
rdtype,
covers,
deleting,
True,
self.one_rr_per_rrset,
)
if rd is not None:
rrset.add(rd, ttl)
def _make_message(self):
factory = _message_factory_from_opcode(self.opcode)
message = factory(id=self.id)
message.flags = self.flags
if self.edns >= 0:
message.use_edns(self.edns, self.ednsflags, self.payload)
if self.rcode:
message.set_rcode(self.rcode)
if self.origin:
message.origin = self.origin
return message
def read(self):
"""Read a text format DNS message and build a dns.message.Message
object."""
line_method = self._header_line
section_number = None
while 1:
token = self.tok.get(True, True)
if token.is_eol_or_eof():
break
if token.is_comment():
u = token.value.upper()
if u == "HEADER":
line_method = self._header_line
if self.message:
message = self.message
else:
# If we don't have a message, create one with the current
# opcode, so that we know which section names to parse.
message = self._make_message()
try:
section_number = message._section_enum.from_text(u)
# We found a section name. If we don't have a message,
# use the one we just created.
if not self.message:
self.message = message
self.one_rr_per_rrset = message._get_one_rr_per_rrset(
self.one_rr_per_rrset
)
if section_number == MessageSection.QUESTION:
line_method = self._question_line
else:
line_method = self._rr_line
except Exception:
# It's just a comment.
pass
self.tok.get_eol()
continue
self.tok.unget(token)
line_method(section_number)
if not self.message:
self.message = self._make_message()
return self.message
def from_text(
text: str,
idna_codec: Optional[dns.name.IDNACodec] = None,
one_rr_per_rrset: bool = False,
origin: Optional[dns.name.Name] = None,
relativize: bool = True,
relativize_to: Optional[dns.name.Name] = None,
) -> Message:
"""Convert the text format message into a message object.
The reader stops after reading the first blank line in the input to
facilitate reading multiple messages from a single file with
``dns.message.from_file()``.
*text*, a ``str``, the text format message.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder
is used.
*one_rr_per_rrset*, a ``bool``. If ``True``, then each RR is put
into its own rrset. The default is ``False``.
*origin*, a ``dns.name.Name`` (or ``None``), the
origin to use for relative names.
*relativize*, a ``bool``. If true, name will be relativized.
*relativize_to*, a ``dns.name.Name`` (or ``None``), the origin to use
when relativizing names. If not set, the *origin* value will be used.
Raises ``dns.message.UnknownHeaderField`` if a header is unknown.
Raises ``dns.exception.SyntaxError`` if the text is badly formed.
Returns a ``dns.message.Message object``
"""
# 'text' can also be a file, but we don't publish that fact
# since it's an implementation detail. The official file
# interface is from_file().
reader = _TextReader(
text, idna_codec, one_rr_per_rrset, origin, relativize, relativize_to
)
return reader.read()
def from_file(
f: Any,
idna_codec: Optional[dns.name.IDNACodec] = None,
one_rr_per_rrset: bool = False,
) -> Message:
"""Read the next text format message from the specified file.
Message blocks are separated by a single blank line.
*f*, a ``file`` or ``str``. If *f* is text, it is treated as the
pathname of a file to open.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder
is used.
*one_rr_per_rrset*, a ``bool``. If ``True``, then each RR is put
into its own rrset. The default is ``False``.
Raises ``dns.message.UnknownHeaderField`` if a header is unknown.
Raises ``dns.exception.SyntaxError`` if the text is badly formed.
Returns a ``dns.message.Message object``
"""
if isinstance(f, str):
cm: contextlib.AbstractContextManager = open(f)
else:
cm = contextlib.nullcontext(f)
with cm as f:
return from_text(f, idna_codec, one_rr_per_rrset)
assert False # for mypy lgtm[py/unreachable-statement]
def make_query(
qname: Union[dns.name.Name, str],
rdtype: Union[dns.rdatatype.RdataType, str],
rdclass: Union[dns.rdataclass.RdataClass, str] = dns.rdataclass.IN,
use_edns: Optional[Union[int, bool]] = None,
want_dnssec: bool = False,
ednsflags: Optional[int] = None,
payload: Optional[int] = None,
request_payload: Optional[int] = None,
options: Optional[List[dns.edns.Option]] = None,
idna_codec: Optional[dns.name.IDNACodec] = None,
id: Optional[int] = None,
flags: int = dns.flags.RD,
pad: int = 0,
) -> QueryMessage:
"""Make a query message.
The query name, type, and class may all be specified either
as objects of the appropriate type, or as strings.
The query will have a randomly chosen query id, and its DNS flags
will be set to dns.flags.RD.
qname, a ``dns.name.Name`` or ``str``, the query name.
*rdtype*, an ``int`` or ``str``, the desired rdata type.
*rdclass*, an ``int`` or ``str``, the desired rdata class; the default
is class IN.
*use_edns*, an ``int``, ``bool`` or ``None``. The EDNS level to use; the
default is ``None``. If ``None``, EDNS will be enabled only if other
parameters (*ednsflags*, *payload*, *request_payload*, or *options*) are
set.
See the description of dns.message.Message.use_edns() for the possible
values for use_edns and their meanings.
*want_dnssec*, a ``bool``. If ``True``, DNSSEC data is desired.
*ednsflags*, an ``int``, the EDNS flag values.
*payload*, an ``int``, is the EDNS sender's payload field, which is the
maximum size of UDP datagram the sender can handle. I.e. how big
a response to this message can be.
*request_payload*, an ``int``, is the EDNS payload size to use when
sending this message. If not specified, defaults to the value of
*payload*.
*options*, a list of ``dns.edns.Option`` objects or ``None``, the EDNS
options.
*idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA
encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder
is used.
*id*, an ``int`` or ``None``, the desired query id. The default is
``None``, which generates a random query id.
*flags*, an ``int``, the desired query flags. The default is
``dns.flags.RD``.
*pad*, a non-negative ``int``. If 0, the default, do not pad; otherwise add
padding bytes to make the message size a multiple of *pad*. Note that if
padding is non-zero, an EDNS PADDING option will always be added to the
message.
Returns a ``dns.message.QueryMessage``
"""
if isinstance(qname, str):
qname = dns.name.from_text(qname, idna_codec=idna_codec)
rdtype = dns.rdatatype.RdataType.make(rdtype)
rdclass = dns.rdataclass.RdataClass.make(rdclass)
m = QueryMessage(id=id)
m.flags = dns.flags.Flag(flags)
m.find_rrset(m.question, qname, rdclass, rdtype, create=True, force_unique=True)
# only pass keywords on to use_edns if they have been set to a
# non-None value. Setting a field will turn EDNS on if it hasn't
# been configured.
kwargs: Dict[str, Any] = {}
if ednsflags is not None:
kwargs["ednsflags"] = ednsflags
if payload is not None:
kwargs["payload"] = payload
if request_payload is not None:
kwargs["request_payload"] = request_payload
if options is not None:
kwargs["options"] = options
if kwargs and use_edns is None:
use_edns = 0
kwargs["edns"] = use_edns
kwargs["pad"] = pad
m.use_edns(**kwargs)
m.want_dnssec(want_dnssec)
return m
def make_response(
query: Message,
recursion_available: bool = False,
our_payload: int = 8192,
fudge: int = 300,
tsig_error: int = 0,
pad: Optional[int] = None,
) -> Message:
"""Make a message which is a response for the specified query.
The message returned is really a response skeleton; it has all of the infrastructure
required of a response, but none of the content.
The response's question section is a shallow copy of the query's question section,
so the query's question RRsets should not be changed.
*query*, a ``dns.message.Message``, the query to respond to.
*recursion_available*, a ``bool``, should RA be set in the response?
*our_payload*, an ``int``, the payload size to advertise in EDNS responses.
*fudge*, an ``int``, the TSIG time fudge.
*tsig_error*, an ``int``, the TSIG error.
*pad*, a non-negative ``int`` or ``None``. If 0, the default, do not pad; otherwise
if not ``None`` add padding bytes to make the message size a multiple of *pad*.
Note that if padding is non-zero, an EDNS PADDING option will always be added to the
message. If ``None``, add padding following RFC 8467, namely if the request is
padded, pad the response to 468 otherwise do not pad.
Returns a ``dns.message.Message`` object whose specific class is appropriate for the
query. For example, if query is a ``dns.update.UpdateMessage``, response will be
too.
"""
if query.flags & dns.flags.QR:
raise dns.exception.FormError("specified query message is not a query")
factory = _message_factory_from_opcode(query.opcode())
response = factory(id=query.id)
response.flags = dns.flags.QR | (query.flags & dns.flags.RD)
if recursion_available:
response.flags |= dns.flags.RA
response.set_opcode(query.opcode())
response.question = list(query.question)
if query.edns >= 0:
if pad is None:
# Set response padding per RFC 8467
pad = 0
for option in query.options:
if option.otype == dns.edns.OptionType.PADDING:
pad = 468
response.use_edns(0, 0, our_payload, query.payload, pad=pad)
if query.had_tsig:
response.use_tsig(
query.keyring,
query.keyname,
fudge,
None,
tsig_error,
b"",
query.keyalgorithm,
)
response.request_mac = query.mac
return response
### BEGIN generated MessageSection constants
QUESTION = MessageSection.QUESTION
ANSWER = MessageSection.ANSWER
AUTHORITY = MessageSection.AUTHORITY
ADDITIONAL = MessageSection.ADDITIONAL
### END generated MessageSection constants
|