# Copyright (C) 2001-2007, 2009, 2010 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 rdata.
@var _rdata_modules: A dictionary mapping a (rdclass, rdtype) tuple to
the module which implements that type.
@type _rdata_modules: dict
@var _module_prefix: The prefix to use when forming modules names. The
default is 'dns.rdtypes'. Changing this value will break the library.
Changed for absolute imports
@type _module_prefix: string
@var _hex_chunk: At most this many octets that will be represented in each
chunk of hexstring that _hexify() produces before whitespace occurs.
@type _hex_chunk: int"""
from __future__ import absolute_import
import cStringIO
from . import exception as dns_exception
from . import rdataclass as dns_rdataclass
from . import rdatatype as dns_rdatatype
from . import tokenizer as dns_tokenizer
if False:
# to trick the module finder of pyinstaller
# but do not compile in python2.5
from .rdtypes.IN import *
from .rdtypes.ANY import *
_hex_chunksize = 32
def _hexify(data, chunksize=None):
"""Convert a binary string into its hex encoding, broken up into chunks
of I{chunksize} characters separated by a space.
@param data: the binary string
@type data: string
@param chunksize: the chunk size. Default is L{dns_rdata._hex_chunksize}
@rtype: string
"""
if chunksize is None:
chunksize = _hex_chunksize
hex = data.encode('hex_codec')
l = len(hex)
if l > chunksize:
chunks = []
i = 0
while i < l:
chunks.append(hex[i : i + chunksize])
i += chunksize
hex = ' '.join(chunks)
return hex
_base64_chunksize = 32
def _base64ify(data, chunksize=None):
"""Convert a binary string into its base64 encoding, broken up into chunks
of I{chunksize} characters separated by a space.
@param data: the binary string
@type data: string
@param chunksize: the chunk size. Default is
L{dns_rdata._base64_chunksize}
@rtype: string
"""
if chunksize is None:
chunksize = _base64_chunksize
b64 = data.encode('base64_codec')
b64 = b64.replace('\n', '')
l = len(b64)
if l > chunksize:
chunks = []
i = 0
while i < l:
chunks.append(b64[i : i + chunksize])
i += chunksize
b64 = ' '.join(chunks)
return b64
__escaped = {
'"' : True,
'\\' : True,
}
def _escapify(qstring):
"""Escape the characters in a quoted string which need it.
@param qstring: the string
@type qstring: string
@returns: the escaped string
@rtype: string
"""
text = ''
for c in qstring:
if c in __escaped:
text += '\\' + c
elif ord(c) >= 0x20 and ord(c) < 0x7F:
text += c
else:
text += '\\%03d' % ord(c)
return text
def _truncate_bitmap(what):
"""Determine the index of greatest byte that isn't all zeros, and
return the bitmap that contains all the bytes less than that index.
@param what: a string of octets representing a bitmap.
@type what: string
@rtype: string
"""
for i in xrange(len(what) - 1, -1, -1):
if what[i] != '\x00':
break
return ''.join(what[0 : i + 1])
[docs]class Rdata(object):
"""Base class for all DNS rdata types.
"""
__slots__ = ['rdclass', 'rdtype']
def __init__(self, rdclass, rdtype):
"""Initialize an rdata.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
"""
self.rdclass = rdclass
self.rdtype = rdtype
[docs] def covers(self):
"""DNS SIG/RRSIG rdatas apply to a specific type; this type is
returned by the covers() function. If the rdata type is not
SIG or RRSIG, dns_rdatatype.NONE is returned. This is useful when
creating rdatasets, allowing the rdataset to contain only RRSIGs
of a particular type, e.g. RRSIG(NS).
@rtype: int
"""
return dns_rdatatype.NONE
[docs] def extended_rdatatype(self):
"""Return a 32-bit type value, the least significant 16 bits of
which are the ordinary DNS type, and the upper 16 bits of which are
the "covered" type, if any.
@rtype: int
"""
return self.covers() << 16 | self.rdtype
[docs] def to_text(self, origin=None, relativize=True, **kw):
"""Convert an rdata to text format.
@rtype: string
"""
raise NotImplementedError
[docs] def to_wire(self, file, compress = None, origin = None):
"""Convert an rdata to wire format.
@rtype: string
"""
raise NotImplementedError
[docs] def to_digestable(self, origin = None):
"""Convert rdata to a format suitable for digesting in hashes. This
is also the DNSSEC canonical form."""
f = cStringIO.StringIO()
self.to_wire(f, None, origin)
return f.getvalue()
[docs] def validate(self):
"""Check that the current contents of the rdata's fields are
valid. If you change an rdata by assigning to its fields,
it is a good idea to call validate() when you are done making
changes.
"""
from_text(self.rdclass, self.rdtype, self.to_text())
def __repr__(self):
covers = self.covers()
if covers == dns_rdatatype.NONE:
ctext = ''
else:
ctext = '(' + dns_rdatatype.to_text(covers) + ')'
return '<DNS ' + dns_rdataclass.to_text(self.rdclass) + ' ' + \
dns_rdatatype.to_text(self.rdtype) + ctext + ' rdata: ' + \
str(self) + '>'
def __str__(self):
return self.to_text()
def _cmp(self, other):
"""Compare an rdata with another rdata of the same rdtype and
rdclass. Return < 0 if self < other in the DNSSEC ordering,
0 if self == other, and > 0 if self > other.
"""
raise NotImplementedError
def __eq__(self, other):
if not isinstance(other, Rdata):
return False
if self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return False
return self._cmp(other) == 0
def __ne__(self, other):
if not isinstance(other, Rdata):
return True
if self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return True
return self._cmp(other) != 0
def __lt__(self, other):
if not isinstance(other, Rdata) or \
self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return NotImplemented
return self._cmp(other) < 0
def __le__(self, other):
if not isinstance(other, Rdata) or \
self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return NotImplemented
return self._cmp(other) <= 0
def __ge__(self, other):
if not isinstance(other, Rdata) or \
self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return NotImplemented
return self._cmp(other) >= 0
def __gt__(self, other):
if not isinstance(other, Rdata) or \
self.rdclass != other.rdclass or \
self.rdtype != other.rdtype:
return NotImplemented
return self._cmp(other) > 0
[docs] def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
"""Build an rdata object from text format.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param tok: The tokenizer
@type tok: dns_tokenizer.Tokenizer
@param origin: The origin to use for relative names
@type origin: dns_name.Name
@param relativize: should names be relativized?
@type relativize: bool
@rtype: dns_rdata.Rdata instance
"""
raise NotImplementedError
from_text = classmethod(from_text)
[docs] def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
"""Build an rdata object from wire format
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param wire: The wire-format message
@type wire: string
@param current: The offet in wire of the beginning of the rdata.
@type current: int
@param rdlen: The length of the wire-format rdata
@type rdlen: int
@param origin: The origin to use for relative names
@type origin: dns_name.Name
@rtype: dns_rdata.Rdata instance
"""
raise NotImplementedError
from_wire = classmethod(from_wire)
[docs] def choose_relativity(self, origin = None, relativize = True):
"""Convert any domain names in the rdata to the specified
relativization.
"""
pass
[docs]class GenericRdata(Rdata):
"""Generate Rdata Class
This class is used for rdata types for which we have no better
implementation. It implements the DNS "unknown RRs" scheme.
"""
__slots__ = ['data']
def __init__(self, rdclass, rdtype, data):
super(GenericRdata, self).__init__(rdclass, rdtype)
self.data = data
[docs] def to_text(self, origin=None, relativize=True, **kw):
return r'\# %d ' % len(self.data) + _hexify(self.data)
[docs] def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
token = tok.get()
if not token.is_identifier() or token.value != '\#':
raise dns_exception.SyntaxError(r'generic rdata does not start with \#')
length = tok.get_int()
chunks = []
while 1:
token = tok.get()
if token.is_eol_or_eof():
break
chunks.append(token.value)
hex = ''.join(chunks)
data = hex.decode('hex_codec')
if len(data) != length:
raise dns_exception.SyntaxError('generic rdata hex data has wrong length')
return cls(rdclass, rdtype, data)
from_text = classmethod(from_text)
[docs] def to_wire(self, file, compress = None, origin = None):
file.write(self.data)
[docs] def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
return cls(rdclass, rdtype, wire[current : current + rdlen])
from_wire = classmethod(from_wire)
def _cmp(self, other):
return cmp(self.data, other.data)
_rdata_modules = {}
_module_prefix = 'rdtypes'
[docs]def get_rdata_class(rdclass, rdtype):
def import_module(name):
# for absolute imports need more arguments: to test
mod = __import__(name, globals=globals(), level=1)
components = name.split('.')
for comp in components[1:]:
mod = getattr(mod, comp)
return mod
mod = _rdata_modules.get((rdclass, rdtype))
rdclass_text = dns_rdataclass.to_text(rdclass)
rdtype_text = dns_rdatatype.to_text(rdtype)
rdtype_text = rdtype_text.replace('-', '_')
if not mod:
mod = _rdata_modules.get((dns_rdatatype.ANY, rdtype))
if not mod:
try:
mod = import_module('.'.join([_module_prefix,
rdclass_text, rdtype_text]))
_rdata_modules[(rdclass, rdtype)] = mod
except ImportError:
try:
mod = import_module('.'.join([_module_prefix,
'ANY', rdtype_text]))
_rdata_modules[(dns_rdataclass.ANY, rdtype)] = mod
except ImportError:
mod = None
if mod:
cls = getattr(mod, rdtype_text)
else:
cls = GenericRdata
return cls
[docs]def from_text(rdclass, rdtype, tok, origin = None, relativize = True):
"""Build an rdata object from text format.
This function attempts to dynamically load a class which
implements the specified rdata class and type. If there is no
class-and-type-specific implementation, the GenericRdata class
is used.
Once a class is chosen, its from_text() class method is called
with the parameters to this function.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param tok: The tokenizer
@type tok: dns_tokenizer.Tokenizer
@param origin: The origin to use for relative names
@type origin: dns_name.Name
@param relativize: Should names be relativized?
@type relativize: bool
@rtype: dns_rdata.Rdata instance"""
if isinstance(tok, str):
tok = dns_tokenizer.Tokenizer(tok)
cls = get_rdata_class(rdclass, rdtype)
if cls != GenericRdata:
# peek at first token
token = tok.get()
tok.unget(token)
if token.is_identifier() and \
token.value == r'\#':
#
# Known type using the generic syntax. Extract the
# wire form from the generic syntax, and then run
# from_wire on it.
#
rdata = GenericRdata.from_text(rdclass, rdtype, tok, origin,
relativize)
return from_wire(rdclass, rdtype, rdata.data, 0, len(rdata.data),
origin)
return cls.from_text(rdclass, rdtype, tok, origin, relativize)
[docs]def from_wire(rdclass, rdtype, wire, current, rdlen, origin = None):
"""Build an rdata object from wire format
This function attempts to dynamically load a class which
implements the specified rdata class and type. If there is no
class-and-type-specific implementation, the GenericRdata class
is used.
Once a class is chosen, its from_wire() class method is called
with the parameters to this function.
@param rdclass: The rdata class
@type rdclass: int
@param rdtype: The rdata type
@type rdtype: int
@param wire: The wire-format message
@type wire: string
@param current: The offet in wire of the beginning of the rdata.
@type current: int
@param rdlen: The length of the wire-format rdata
@type rdlen: int
@param origin: The origin to use for relative names
@type origin: dns_name.Name
@rtype: dns_rdata.Rdata instance"""
cls = get_rdata_class(rdclass, rdtype)
return cls.from_wire(rdclass, rdtype, wire, current, rdlen, origin)