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- # Copyright (C) 2001-2007, 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 Message Flags."""
- # Standard DNS flags
- QR = 0x8000
- AA = 0x0400
- TC = 0x0200
- RD = 0x0100
- RA = 0x0080
- AD = 0x0020
- CD = 0x0010
- # EDNS flags
- DO = 0x8000
- _by_text = {
- 'QR': QR,
- 'AA': AA,
- 'TC': TC,
- 'RD': RD,
- 'RA': RA,
- 'AD': AD,
- 'CD': CD
- }
- _edns_by_text = {
- 'DO': DO
- }
- # We construct the inverse mappings programmatically to ensure that we
- # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
- # would cause the mappings not to be true inverses.
- _by_value = dict((y, x) for x, y in _by_text.items())
- _edns_by_value = dict((y, x) for x, y in _edns_by_text.items())
- def _order_flags(table):
- order = list(table.items())
- order.sort()
- order.reverse()
- return order
- _flags_order = _order_flags(_by_value)
- _edns_flags_order = _order_flags(_edns_by_value)
- def _from_text(text, table):
- flags = 0
- tokens = text.split()
- for t in tokens:
- flags = flags | table[t.upper()]
- return flags
- def _to_text(flags, table, order):
- text_flags = []
- for k, v in order:
- if flags & k != 0:
- text_flags.append(v)
- return ' '.join(text_flags)
- def from_text(text):
- """Convert a space-separated list of flag text values into a flags
- value.
- @rtype: int"""
- return _from_text(text, _by_text)
- def to_text(flags):
- """Convert a flags value into a space-separated list of flag text
- values.
- @rtype: string"""
- return _to_text(flags, _by_value, _flags_order)
- def edns_from_text(text):
- """Convert a space-separated list of EDNS flag text values into a EDNS
- flags value.
- @rtype: int"""
- return _from_text(text, _edns_by_text)
- def edns_to_text(flags):
- """Convert an EDNS flags value into a space-separated list of EDNS flag
- text values.
- @rtype: string"""
- return _to_text(flags, _edns_by_value, _edns_flags_order)
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