| 1 | # Copyright (C) 2001-2007, 2009, 2010 Nominum, Inc.
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| 2 | #
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| 3 | # Permission to use, copy, modify, and distribute this software and its
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| 4 | # documentation for any purpose with or without fee is hereby granted,
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| 5 | # provided that the above copyright notice and this permission notice
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| 6 | # appear in all copies.
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| 7 | #
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| 8 | # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
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| 9 | # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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| 10 | # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
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| 11 | # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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| 12 | # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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| 13 | # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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| 14 | # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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| 15 |
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| 16 | """DNS Message Flags."""
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| 17 |
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| 18 | # Standard DNS flags
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| 19 |
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| 20 | QR = 0x8000
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| 21 | AA = 0x0400
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| 22 | TC = 0x0200
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| 23 | RD = 0x0100
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| 24 | RA = 0x0080
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| 25 | AD = 0x0020
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| 26 | CD = 0x0010
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| 27 |
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| 28 | # EDNS flags
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| 29 |
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| 30 | DO = 0x8000
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| 31 |
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| 32 | _by_text = {
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| 33 | 'QR' : QR,
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| 34 | 'AA' : AA,
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| 35 | 'TC' : TC,
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| 36 | 'RD' : RD,
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| 37 | 'RA' : RA,
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| 38 | 'AD' : AD,
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| 39 | 'CD' : CD
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| 40 | }
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| 41 |
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| 42 | _edns_by_text = {
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| 43 | 'DO' : DO
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| 44 | }
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| 45 |
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| 46 |
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| 47 | # We construct the inverse mappings programmatically to ensure that we
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| 48 | # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
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| 49 | # would cause the mappings not to be true inverses.
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| 50 |
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| 51 | _by_value = dict([(y, x) for x, y in _by_text.iteritems()])
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| 52 |
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| 53 | _edns_by_value = dict([(y, x) for x, y in _edns_by_text.iteritems()])
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| 54 |
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| 55 | def _order_flags(table):
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| 56 | order = list(table.iteritems())
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| 57 | order.sort()
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| 58 | order.reverse()
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| 59 | return order
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| 60 |
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| 61 | _flags_order = _order_flags(_by_value)
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| 62 |
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| 63 | _edns_flags_order = _order_flags(_edns_by_value)
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| 64 |
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| 65 | def _from_text(text, table):
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| 66 | flags = 0
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| 67 | tokens = text.split()
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| 68 | for t in tokens:
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| 69 | flags = flags | table[t.upper()]
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| 70 | return flags
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| 71 |
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| 72 | def _to_text(flags, table, order):
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| 73 | text_flags = []
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| 74 | for k, v in order:
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| 75 | if flags & k != 0:
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| 76 | text_flags.append(v)
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| 77 | return ' '.join(text_flags)
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| 78 |
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| 79 | def from_text(text):
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| 80 | """Convert a space-separated list of flag text values into a flags
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| 81 | value.
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| 82 | @rtype: int"""
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| 83 |
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| 84 | return _from_text(text, _by_text)
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| 85 |
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| 86 | def to_text(flags):
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| 87 | """Convert a flags value into a space-separated list of flag text
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| 88 | values.
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| 89 | @rtype: string"""
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| 90 |
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| 91 | return _to_text(flags, _by_value, _flags_order)
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| 92 |
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| 93 |
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| 94 | def edns_from_text(text):
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| 95 | """Convert a space-separated list of EDNS flag text values into a EDNS
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| 96 | flags value.
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| 97 | @rtype: int"""
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| 98 |
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| 99 | return _from_text(text, _edns_by_text)
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| 100 |
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| 101 | def edns_to_text(flags):
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| 102 | """Convert an EDNS flags value into a space-separated list of EDNS flag
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| 103 | text values.
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| 104 | @rtype: string"""
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| 105 |
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| 106 | return _to_text(flags, _edns_by_value, _edns_flags_order)
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