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# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2004-2007, 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.
import io
import struct
import dns.exception
import dns.rdata
import dns.rdatatype
import dns.name
class NSEC(dns.rdata.Rdata):
"""NSEC record"""
__slots__ = ['next', 'windows']
def __init__(self, rdclass, rdtype, next, windows):
super().__init__(rdclass, rdtype)
object.__setattr__(self, 'next', next)
object.__setattr__(self, 'windows', dns.rdata._constify(windows))
def to_text(self, origin=None, relativize=True, **kw):
next = self.next.choose_relativity(origin, relativize)
text = ''
for (window, bitmap) in self.windows:
bits = []
for (i, byte) in enumerate(bitmap):
for j in range(0, 8):
if byte & (0x80 >> j):
bits.append(dns.rdatatype.to_text(window * 256 +
i * 8 + j))
text += (' ' + ' '.join(bits))
return '{}{}'.format(next, text)
@classmethod
def from_text(cls, rdclass, rdtype, tok, origin=None, relativize=True,
relativize_to=None):
next = tok.get_name(origin, relativize, relativize_to)
rdtypes = []
while 1:
token = tok.get().unescape()
if token.is_eol_or_eof():
break
nrdtype = dns.rdatatype.from_text(token.value)
if nrdtype == 0:
raise dns.exception.SyntaxError("NSEC with bit 0")
if nrdtype > 65535:
raise dns.exception.SyntaxError("NSEC with bit > 65535")
rdtypes.append(nrdtype)
rdtypes.sort()
window = 0
octets = 0
prior_rdtype = 0
bitmap = bytearray(b'\0' * 32)
windows = []
for nrdtype in rdtypes:
if nrdtype == prior_rdtype:
continue
prior_rdtype = nrdtype
new_window = nrdtype // 256
if new_window != window:
windows.append((window, bitmap[0:octets]))
bitmap = bytearray(b'\0' * 32)
window = new_window
offset = nrdtype % 256
byte = offset // 8
bit = offset % 8
octets = byte + 1
bitmap[byte] = bitmap[byte] | (0x80 >> bit)
windows.append((window, bitmap[0:octets]))
return cls(rdclass, rdtype, next, windows)
def to_wire(self, file, compress=None, origin=None):
self.next.to_wire(file, None, origin)
for (window, bitmap) in self.windows:
file.write(struct.pack('!BB', window, len(bitmap)))
file.write(bitmap)
def to_digestable(self, origin=None):
file = io.BytesIO()
file.write(self.next.to_digestable(origin))
for (window, bitmap) in self.windows:
file.write(struct.pack('!BB', window, len(bitmap)))
file.write(bitmap)
return file.getvalue()
@classmethod
def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin=None):
(next, cused) = dns.name.from_wire(wire[: current + rdlen], current)
current += cused
rdlen -= cused
windows = []
while rdlen > 0:
if rdlen < 3:
raise dns.exception.FormError("NSEC too short")
window = wire[current]
octets = wire[current + 1]
if octets == 0 or octets > 32:
raise dns.exception.FormError("bad NSEC octets")
current += 2
rdlen -= 2
if rdlen < octets:
raise dns.exception.FormError("bad NSEC bitmap length")
bitmap = bytearray(wire[current: current + octets].unwrap())
current += octets
rdlen -= octets
windows.append((window, bitmap))
if origin is not None:
next = next.relativize(origin)
return cls(rdclass, rdtype, next, windows)
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