| # 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 |