129 lines
2.8 KiB
Python
129 lines
2.8 KiB
Python
# Copyright (C) 2001-2017 Nominum, Inc.
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#
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# Permission to use, copy, modify, and distribute this software and its
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# documentation for any purpose with or without fee is hereby granted,
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# provided that the above copyright notice and this permission notice
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# appear in all copies.
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#
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# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
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# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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"""DNS Message Flags."""
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# Standard DNS flags
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#: Query Response
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QR = 0x8000
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#: Authoritative Answer
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AA = 0x0400
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#: Truncated Response
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TC = 0x0200
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#: Recursion Desired
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RD = 0x0100
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#: Recursion Available
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RA = 0x0080
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#: Authentic Data
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AD = 0x0020
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#: Checking Disabled
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CD = 0x0010
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# EDNS flags
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#: DNSSEC answer OK
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DO = 0x8000
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_by_text = {
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'QR': QR,
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'AA': AA,
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'TC': TC,
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'RD': RD,
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'RA': RA,
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'AD': AD,
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'CD': CD
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}
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_edns_by_text = {
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'DO': DO
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}
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# We construct the inverse mappings programmatically to ensure that we
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# cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
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# would cause the mappings not to be true inverses.
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_by_value = dict((y, x) for x, y in _by_text.items())
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_edns_by_value = dict((y, x) for x, y in _edns_by_text.items())
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def _order_flags(table):
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order = list(table.items())
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order.sort()
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order.reverse()
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return order
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_flags_order = _order_flags(_by_value)
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_edns_flags_order = _order_flags(_edns_by_value)
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def _from_text(text, table):
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flags = 0
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tokens = text.split()
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for t in tokens:
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flags = flags | table[t.upper()]
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return flags
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def _to_text(flags, table, order):
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text_flags = []
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for k, v in order:
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if flags & k != 0:
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text_flags.append(v)
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return ' '.join(text_flags)
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def from_text(text):
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"""Convert a space-separated list of flag text values into a flags
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value.
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Returns an ``int``
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"""
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return _from_text(text, _by_text)
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def to_text(flags):
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"""Convert a flags value into a space-separated list of flag text
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values.
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Returns a ``text``.
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"""
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return _to_text(flags, _by_value, _flags_order)
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def edns_from_text(text):
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"""Convert a space-separated list of EDNS flag text values into a EDNS
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flags value.
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Returns an ``int``
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"""
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return _from_text(text, _edns_by_text)
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def edns_to_text(flags):
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"""Convert an EDNS flags value into a space-separated list of EDNS flag
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text values.
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Returns a ``text``.
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"""
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return _to_text(flags, _edns_by_value, _edns_flags_order)
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