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# Copyright (C) 2004-2007, 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.
import cStringIO
import dns.exception
import dns.rdata
import dns.rdatatype
import dns.name
class NSEC(dns.rdata.Rdata):
"""NSEC record
@ivar next: the next name
@type next: dns.name.Name object
@ivar windows: the windowed bitmap list
@type windows: list of (window number, string) tuples"""
__slots__ = ['next', 'windows']
def __init__(self, rdclass, rdtype, next, windows):
super(NSEC, self).__init__(rdclass, rdtype)
self.next = next
self.windows = 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 in xrange(0, len(bitmap)):
byte = ord(bitmap[i])
for j in xrange(0, 8):
if byte & (0x80 >> j):
bits.append(dns.rdatatype.to_text(window * 256 + \
i * 8 + j))
text += (' ' + ' '.join(bits))
return '%s%s' % (next, text)
def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
next = tok.get_name()
next = next.choose_relativity(origin, relativize)
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 = ['\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, ''.join(bitmap[0:octets])))
bitmap = ['\0'] * 32
window = new_window
offset = nrdtype % 256
byte = offset / 8
bit = offset % 8
octets = byte + 1
bitmap[byte] = chr(ord(bitmap[byte]) | (0x80 >> bit))
windows.append((window, ''.join(bitmap[0:octets])))
return cls(rdclass, rdtype, next, windows)
from_text = classmethod(from_text)
def to_wire(self, file, compress = None, origin = None):
self.next.to_wire(file, None, origin)
for (window, bitmap) in self.windows:
file.write(chr(window))
file.write(chr(len(bitmap)))
file.write(bitmap)
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 = ord(wire[current])
octets = ord(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 = wire[current : current + octets]
current += octets
rdlen -= octets
windows.append((window, bitmap))
if not origin is None:
next = next.relativize(origin)
return cls(rdclass, rdtype, next, windows)
from_wire = classmethod(from_wire)
def choose_relativity(self, origin = None, relativize = True):
self.next = self.next.choose_relativity(origin, relativize)
def _cmp(self, other):
v = cmp(self.next, other.next)
if v == 0:
b1 = cStringIO.StringIO()
for (window, bitmap) in self.windows:
b1.write(chr(window))
b1.write(chr(len(bitmap)))
b1.write(bitmap)
b2 = cStringIO.StringIO()
for (window, bitmap) in other.windows:
b2.write(chr(window))
b2.write(chr(len(bitmap)))
b2.write(bitmap)
v = cmp(b1.getvalue(), b2.getvalue())
return v
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