Source code for dns.zonefile

# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license

# 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 Zones."""

import re
import sys
from typing import Any, Iterable, List, Optional, Set, Tuple, Union

import dns.exception
import dns.grange
import dns.name
import dns.node
import dns.rdata
import dns.rdataclass
import dns.rdatatype
import dns.rdtypes.ANY.SOA
import dns.rrset
import dns.tokenizer
import dns.transaction
import dns.ttl


class UnknownOrigin(dns.exception.DNSException):
    """Unknown origin"""


class CNAMEAndOtherData(dns.exception.DNSException):
    """A node has a CNAME and other data"""


def _check_cname_and_other_data(txn, name, rdataset):
    rdataset_kind = dns.node.NodeKind.classify_rdataset(rdataset)
    node = txn.get_node(name)
    if node is None:
        # empty nodes are neutral.
        return
    node_kind = node.classify()
    if (
        node_kind == dns.node.NodeKind.CNAME
        and rdataset_kind == dns.node.NodeKind.REGULAR
    ):
        raise CNAMEAndOtherData("rdataset type is not compatible with a CNAME node")
    elif (
        node_kind == dns.node.NodeKind.REGULAR
        and rdataset_kind == dns.node.NodeKind.CNAME
    ):
        raise CNAMEAndOtherData(
            "CNAME rdataset is not compatible with a regular data node"
        )
    # Otherwise at least one of the node and the rdataset is neutral, so
    # adding the rdataset is ok


SavedStateType = Tuple[
    dns.tokenizer.Tokenizer,
    Optional[dns.name.Name],  # current_origin
    Optional[dns.name.Name],  # last_name
    Optional[Any],  # current_file
    int,  # last_ttl
    bool,  # last_ttl_known
    int,  # default_ttl
    bool,
]  # default_ttl_known


def _upper_dollarize(s):
    s = s.upper()
    if not s.startswith("$"):
        s = "$" + s
    return s


[docs] class Reader: """Read a DNS zone file into a transaction.""" def __init__( self, tok: dns.tokenizer.Tokenizer, rdclass: dns.rdataclass.RdataClass, txn: dns.transaction.Transaction, allow_include: bool = False, allow_directives: Union[bool, Iterable[str]] = True, force_name: Optional[dns.name.Name] = None, force_ttl: Optional[int] = None, force_rdclass: Optional[dns.rdataclass.RdataClass] = None, force_rdtype: Optional[dns.rdatatype.RdataType] = None, default_ttl: Optional[int] = None, ): self.tok = tok (self.zone_origin, self.relativize, _) = txn.manager.origin_information() self.current_origin = self.zone_origin self.last_ttl = 0 self.last_ttl_known = False if force_ttl is not None: default_ttl = force_ttl if default_ttl is None: self.default_ttl = 0 self.default_ttl_known = False else: self.default_ttl = default_ttl self.default_ttl_known = True self.last_name = self.current_origin self.zone_rdclass = rdclass self.txn = txn self.saved_state: List[SavedStateType] = [] self.current_file: Optional[Any] = None self.allowed_directives: Set[str] if allow_directives is True: self.allowed_directives = {"$GENERATE", "$ORIGIN", "$TTL"} if allow_include: self.allowed_directives.add("$INCLUDE") elif allow_directives is False: # allow_include was ignored in earlier releases if allow_directives was # False, so we continue that. self.allowed_directives = set() else: # Note that if directives are explicitly specified, then allow_include # is ignored. self.allowed_directives = set(_upper_dollarize(d) for d in allow_directives) self.force_name = force_name self.force_ttl = force_ttl self.force_rdclass = force_rdclass self.force_rdtype = force_rdtype self.txn.check_put_rdataset(_check_cname_and_other_data) def _eat_line(self): while 1: token = self.tok.get() if token.is_eol_or_eof(): break def _get_identifier(self): token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError return token def _rr_line(self): """Process one line from a DNS zone file.""" token = None # Name if self.force_name is not None: name = self.force_name else: if self.current_origin is None: raise UnknownOrigin token = self.tok.get(want_leading=True) if not token.is_whitespace(): self.last_name = self.tok.as_name(token, self.current_origin) else: token = self.tok.get() if token.is_eol_or_eof(): # treat leading WS followed by EOL/EOF as if they were EOL/EOF. return self.tok.unget(token) name = self.last_name if not name.is_subdomain(self.zone_origin): self._eat_line() return if self.relativize: name = name.relativize(self.zone_origin) # TTL if self.force_ttl is not None: ttl = self.force_ttl self.last_ttl = ttl self.last_ttl_known = True else: token = self._get_identifier() ttl = None try: ttl = dns.ttl.from_text(token.value) self.last_ttl = ttl self.last_ttl_known = True token = None except dns.ttl.BadTTL: self.tok.unget(token) # Class if self.force_rdclass is not None: rdclass = self.force_rdclass else: token = self._get_identifier() try: rdclass = dns.rdataclass.from_text(token.value) except dns.exception.SyntaxError: raise except Exception: rdclass = self.zone_rdclass self.tok.unget(token) if rdclass != self.zone_rdclass: raise dns.exception.SyntaxError("RR class is not zone's class") if ttl is None: # support for <class> <ttl> <type> syntax token = self._get_identifier() ttl = None try: ttl = dns.ttl.from_text(token.value) self.last_ttl = ttl self.last_ttl_known = True token = None except dns.ttl.BadTTL: if self.default_ttl_known: ttl = self.default_ttl elif self.last_ttl_known: ttl = self.last_ttl self.tok.unget(token) # Type if self.force_rdtype is not None: rdtype = self.force_rdtype else: token = self._get_identifier() try: rdtype = dns.rdatatype.from_text(token.value) except Exception: raise dns.exception.SyntaxError("unknown rdatatype '%s'" % token.value) try: rd = dns.rdata.from_text( rdclass, rdtype, self.tok, self.current_origin, self.relativize, self.zone_origin, ) except dns.exception.SyntaxError: # Catch and reraise. raise except Exception: # All exceptions that occur in the processing of rdata # are treated as syntax errors. This is not strictly # correct, but it is correct almost all of the time. # We convert them to syntax errors so that we can emit # helpful filename:line info. (ty, va) = sys.exc_info()[:2] raise dns.exception.SyntaxError( "caught exception {}: {}".format(str(ty), str(va)) ) if not self.default_ttl_known and rdtype == dns.rdatatype.SOA: # The pre-RFC2308 and pre-BIND9 behavior inherits the zone default # TTL from the SOA minttl if no $TTL statement is present before the # SOA is parsed. self.default_ttl = rd.minimum self.default_ttl_known = True if ttl is None: # if we didn't have a TTL on the SOA, set it! ttl = rd.minimum # TTL check. We had to wait until now to do this as the SOA RR's # own TTL can be inferred from its minimum. if ttl is None: raise dns.exception.SyntaxError("Missing default TTL value") self.txn.add(name, ttl, rd) def _parse_modify(self, side: str) -> Tuple[str, str, int, int, str]: # Here we catch everything in '{' '}' in a group so we can replace it # with ''. is_generate1 = re.compile(r"^.*\$({(\+|-?)(\d+),(\d+),(.)}).*$") is_generate2 = re.compile(r"^.*\$({(\+|-?)(\d+)}).*$") is_generate3 = re.compile(r"^.*\$({(\+|-?)(\d+),(\d+)}).*$") # Sometimes there are modifiers in the hostname. These come after # the dollar sign. They are in the form: ${offset[,width[,base]]}. # Make names g1 = is_generate1.match(side) if g1: mod, sign, offset, width, base = g1.groups() if sign == "": sign = "+" g2 = is_generate2.match(side) if g2: mod, sign, offset = g2.groups() if sign == "": sign = "+" width = 0 base = "d" g3 = is_generate3.match(side) if g3: mod, sign, offset, width = g3.groups() if sign == "": sign = "+" base = "d" if not (g1 or g2 or g3): mod = "" sign = "+" offset = 0 width = 0 base = "d" offset = int(offset) width = int(width) if sign not in ["+", "-"]: raise dns.exception.SyntaxError("invalid offset sign %s" % sign) if base not in ["d", "o", "x", "X", "n", "N"]: raise dns.exception.SyntaxError("invalid type %s" % base) return mod, sign, offset, width, base def _generate_line(self): # range lhs [ttl] [class] type rhs [ comment ] """Process one line containing the GENERATE statement from a DNS zone file.""" if self.current_origin is None: raise UnknownOrigin token = self.tok.get() # Range (required) try: start, stop, step = dns.grange.from_text(token.value) token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError except Exception: raise dns.exception.SyntaxError # lhs (required) try: lhs = token.value token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError except Exception: raise dns.exception.SyntaxError # TTL try: ttl = dns.ttl.from_text(token.value) self.last_ttl = ttl self.last_ttl_known = True token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError except dns.ttl.BadTTL: if not (self.last_ttl_known or self.default_ttl_known): raise dns.exception.SyntaxError("Missing default TTL value") if self.default_ttl_known: ttl = self.default_ttl elif self.last_ttl_known: ttl = self.last_ttl # 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 = self.zone_rdclass if rdclass != self.zone_rdclass: raise dns.exception.SyntaxError("RR class is not zone's class") # Type try: rdtype = dns.rdatatype.from_text(token.value) token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError except Exception: raise dns.exception.SyntaxError("unknown rdatatype '%s'" % token.value) # rhs (required) rhs = token.value def _calculate_index(counter: int, offset_sign: str, offset: int) -> int: """Calculate the index from the counter and offset.""" if offset_sign == "-": offset *= -1 return counter + offset def _format_index(index: int, base: str, width: int) -> str: """Format the index with the given base, and zero-fill it to the given width.""" if base in ["d", "o", "x", "X"]: return format(index, base).zfill(width) # base can only be n or N here hexa = _format_index(index, "x", width) nibbles = ".".join(hexa[::-1])[:width] if base == "N": nibbles = nibbles.upper() return nibbles lmod, lsign, loffset, lwidth, lbase = self._parse_modify(lhs) rmod, rsign, roffset, rwidth, rbase = self._parse_modify(rhs) for i in range(start, stop + 1, step): # +1 because bind is inclusive and python is exclusive lindex = _calculate_index(i, lsign, loffset) rindex = _calculate_index(i, rsign, roffset) lzfindex = _format_index(lindex, lbase, lwidth) rzfindex = _format_index(rindex, rbase, rwidth) name = lhs.replace("$%s" % (lmod), lzfindex) rdata = rhs.replace("$%s" % (rmod), rzfindex) self.last_name = dns.name.from_text( name, self.current_origin, self.tok.idna_codec ) name = self.last_name if not name.is_subdomain(self.zone_origin): self._eat_line() return if self.relativize: name = name.relativize(self.zone_origin) try: rd = dns.rdata.from_text( rdclass, rdtype, rdata, self.current_origin, self.relativize, self.zone_origin, ) except dns.exception.SyntaxError: # Catch and reraise. raise except Exception: # All exceptions that occur in the processing of rdata # are treated as syntax errors. This is not strictly # correct, but it is correct almost all of the time. # We convert them to syntax errors so that we can emit # helpful filename:line info. (ty, va) = sys.exc_info()[:2] raise dns.exception.SyntaxError( "caught exception %s: %s" % (str(ty), str(va)) ) self.txn.add(name, ttl, rd)
[docs] def read(self) -> None: """Read a DNS zone file and build a zone object. @raises dns.zone.NoSOA: No SOA RR was found at the zone origin @raises dns.zone.NoNS: No NS RRset was found at the zone origin """ try: while 1: token = self.tok.get(True, True) if token.is_eof(): if self.current_file is not None: self.current_file.close() if len(self.saved_state) > 0: ( self.tok, self.current_origin, self.last_name, self.current_file, self.last_ttl, self.last_ttl_known, self.default_ttl, self.default_ttl_known, ) = self.saved_state.pop(-1) continue break elif token.is_eol(): continue elif token.is_comment(): self.tok.get_eol() continue elif token.value[0] == "$" and len(self.allowed_directives) > 0: # Note that we only run directive processing code if at least # one directive is allowed in order to be backwards compatible c = token.value.upper() if c not in self.allowed_directives: raise dns.exception.SyntaxError( f"zone file directive '{c}' is not allowed" ) if c == "$TTL": token = self.tok.get() if not token.is_identifier(): raise dns.exception.SyntaxError("bad $TTL") self.default_ttl = dns.ttl.from_text(token.value) self.default_ttl_known = True self.tok.get_eol() elif c == "$ORIGIN": self.current_origin = self.tok.get_name() self.tok.get_eol() if self.zone_origin is None: self.zone_origin = self.current_origin self.txn._set_origin(self.current_origin) elif c == "$INCLUDE": token = self.tok.get() filename = token.value token = self.tok.get() new_origin: Optional[dns.name.Name] if token.is_identifier(): new_origin = dns.name.from_text( token.value, self.current_origin, self.tok.idna_codec ) self.tok.get_eol() elif not token.is_eol_or_eof(): raise dns.exception.SyntaxError("bad origin in $INCLUDE") else: new_origin = self.current_origin self.saved_state.append( ( self.tok, self.current_origin, self.last_name, self.current_file, self.last_ttl, self.last_ttl_known, self.default_ttl, self.default_ttl_known, ) ) self.current_file = open(filename, "r") self.tok = dns.tokenizer.Tokenizer(self.current_file, filename) self.current_origin = new_origin elif c == "$GENERATE": self._generate_line() else: raise dns.exception.SyntaxError( f"Unknown zone file directive '{c}'" ) continue self.tok.unget(token) self._rr_line() except dns.exception.SyntaxError as detail: (filename, line_number) = self.tok.where() if detail is None: detail = "syntax error" ex = dns.exception.SyntaxError( "%s:%d: %s" % (filename, line_number, detail) ) tb = sys.exc_info()[2] raise ex.with_traceback(tb) from None
class RRsetsReaderTransaction(dns.transaction.Transaction): def __init__(self, manager, replacement, read_only): assert not read_only super().__init__(manager, replacement, read_only) self.rdatasets = {} def _get_rdataset(self, name, rdtype, covers): return self.rdatasets.get((name, rdtype, covers)) def _get_node(self, name): rdatasets = [] for (rdataset_name, _, _), rdataset in self.rdatasets.items(): if name == rdataset_name: rdatasets.append(rdataset) if len(rdatasets) == 0: return None node = dns.node.Node() node.rdatasets = rdatasets return node def _put_rdataset(self, name, rdataset): self.rdatasets[(name, rdataset.rdtype, rdataset.covers)] = rdataset def _delete_name(self, name): # First remove any changes involving the name remove = [] for key in self.rdatasets: if key[0] == name: remove.append(key) if len(remove) > 0: for key in remove: del self.rdatasets[key] def _delete_rdataset(self, name, rdtype, covers): try: del self.rdatasets[(name, rdtype, covers)] except KeyError: pass def _name_exists(self, name): for n, _, _ in self.rdatasets: if n == name: return True return False def _changed(self): return len(self.rdatasets) > 0 def _end_transaction(self, commit): if commit and self._changed(): rrsets = [] for (name, _, _), rdataset in self.rdatasets.items(): rrset = dns.rrset.RRset( name, rdataset.rdclass, rdataset.rdtype, rdataset.covers ) rrset.update(rdataset) rrsets.append(rrset) self.manager.set_rrsets(rrsets) def _set_origin(self, origin): pass def _iterate_rdatasets(self): raise NotImplementedError # pragma: no cover def _iterate_names(self): raise NotImplementedError # pragma: no cover class RRSetsReaderManager(dns.transaction.TransactionManager): def __init__( self, origin=dns.name.root, relativize=False, rdclass=dns.rdataclass.IN ): self.origin = origin self.relativize = relativize self.rdclass = rdclass self.rrsets = [] def reader(self): # pragma: no cover raise NotImplementedError def writer(self, replacement=False): assert replacement is True return RRsetsReaderTransaction(self, True, False) def get_class(self): return self.rdclass def origin_information(self): if self.relativize: effective = dns.name.empty else: effective = self.origin return (self.origin, self.relativize, effective) def set_rrsets(self, rrsets): self.rrsets = rrsets
[docs] def read_rrsets( text: Any, name: Optional[Union[dns.name.Name, str]] = None, ttl: Optional[int] = None, rdclass: Optional[Union[dns.rdataclass.RdataClass, str]] = dns.rdataclass.IN, default_rdclass: Union[dns.rdataclass.RdataClass, str] = dns.rdataclass.IN, rdtype: Optional[Union[dns.rdatatype.RdataType, str]] = None, default_ttl: Optional[Union[int, str]] = None, idna_codec: Optional[dns.name.IDNACodec] = None, origin: Optional[Union[dns.name.Name, str]] = dns.name.root, relativize: bool = False, ) -> List[dns.rrset.RRset]: """Read one or more rrsets from the specified text, possibly subject to restrictions. *text*, a file object or a string, is the input to process. *name*, a string, ``dns.name.Name``, or ``None``, is the owner name of the rrset. If not ``None``, then the owner name is "forced", and the input must not specify an owner name. If ``None``, then any owner names are allowed and must be present in the input. *ttl*, an ``int``, string, or None. If not ``None``, the the TTL is forced to be the specified value and the input must not specify a TTL. If ``None``, then a TTL may be specified in the input. If it is not specified, then the *default_ttl* will be used. *rdclass*, a ``dns.rdataclass.RdataClass``, string, or ``None``. If not ``None``, then the class is forced to the specified value, and the input must not specify a class. If ``None``, then the input may specify a class that matches *default_rdclass*. Note that it is not possible to return rrsets with differing classes; specifying ``None`` for the class simply allows the user to optionally type a class as that may be convenient when cutting and pasting. *default_rdclass*, a ``dns.rdataclass.RdataClass`` or string. The class of the returned rrsets. *rdtype*, a ``dns.rdatatype.RdataType``, string, or ``None``. If not ``None``, then the type is forced to the specified value, and the input must not specify a type. If ``None``, then a type must be present for each RR. *default_ttl*, an ``int``, string, or ``None``. If not ``None``, then if the TTL is not forced and is not specified, then this value will be used. if ``None``, then if the TTL is not forced an error will occur if the TTL is not specified. *idna_codec*, a ``dns.name.IDNACodec``, specifies the IDNA encoder/decoder. If ``None``, the default IDNA 2003 encoder/decoder is used. Note that codecs only apply to the owner name; dnspython does not do IDNA for names in rdata, as there is no IDNA zonefile format. *origin*, a string, ``dns.name.Name``, or ``None``, is the origin for any relative names in the input, and also the origin to relativize to if *relativize* is ``True``. *relativize*, a bool. If ``True``, names are relativized to the *origin*; if ``False`` then any relative names in the input are made absolute by appending the *origin*. """ if isinstance(origin, str): origin = dns.name.from_text(origin, dns.name.root, idna_codec) if isinstance(name, str): name = dns.name.from_text(name, origin, idna_codec) if isinstance(ttl, str): ttl = dns.ttl.from_text(ttl) if isinstance(default_ttl, str): default_ttl = dns.ttl.from_text(default_ttl) if rdclass is not None: rdclass = dns.rdataclass.RdataClass.make(rdclass) else: rdclass = None default_rdclass = dns.rdataclass.RdataClass.make(default_rdclass) if rdtype is not None: rdtype = dns.rdatatype.RdataType.make(rdtype) else: rdtype = None manager = RRSetsReaderManager(origin, relativize, default_rdclass) with manager.writer(True) as txn: tok = dns.tokenizer.Tokenizer(text, "<input>", idna_codec=idna_codec) reader = Reader( tok, default_rdclass, txn, allow_directives=False, force_name=name, force_ttl=ttl, force_rdclass=rdclass, force_rdtype=rdtype, default_ttl=default_ttl, ) reader.read() return manager.rrsets