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92 lines
2.9 KiB
92 lines
2.9 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license |
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# Copyright (C) 2003-2017 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 TTL conversion.""" |
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from typing import Union |
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import dns.exception |
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# Technically TTLs are supposed to be between 0 and 2**31 - 1, with values |
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# greater than that interpreted as 0, but we do not impose this policy here |
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# as values > 2**31 - 1 occur in real world data. |
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# |
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# We leave it to applications to impose tighter bounds if desired. |
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MAX_TTL = 2**32 - 1 |
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class BadTTL(dns.exception.SyntaxError): |
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"""DNS TTL value is not well-formed.""" |
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def from_text(text: str) -> int: |
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"""Convert the text form of a TTL to an integer. |
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The BIND 8 units syntax for TTLs (e.g. '1w6d4h3m10s') is supported. |
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*text*, a ``str``, the textual TTL. |
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Raises ``dns.ttl.BadTTL`` if the TTL is not well-formed. |
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Returns an ``int``. |
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""" |
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if text.isdigit(): |
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total = int(text) |
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elif len(text) == 0: |
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raise BadTTL |
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else: |
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total = 0 |
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current = 0 |
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need_digit = True |
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for c in text: |
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if c.isdigit(): |
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current *= 10 |
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current += int(c) |
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need_digit = False |
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else: |
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if need_digit: |
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raise BadTTL |
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c = c.lower() |
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if c == "w": |
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total += current * 604800 |
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elif c == "d": |
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total += current * 86400 |
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elif c == "h": |
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total += current * 3600 |
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elif c == "m": |
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total += current * 60 |
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elif c == "s": |
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total += current |
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else: |
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raise BadTTL("unknown unit '%s'" % c) |
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current = 0 |
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need_digit = True |
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if not current == 0: |
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raise BadTTL("trailing integer") |
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if total < 0 or total > MAX_TTL: |
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raise BadTTL("TTL should be between 0 and 2**32 - 1 (inclusive)") |
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return total |
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def make(value: Union[int, str]) -> int: |
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if isinstance(value, int): |
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return value |
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elif isinstance(value, str): |
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return dns.ttl.from_text(value) |
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else: |
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raise ValueError("cannot convert value to TTL")
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