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