93 lines
2.9 KiB
Python
93 lines
2.9 KiB
Python
|
# 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")
|