linkchecker/linkcheck/dns/ttl.py

# -*- coding: iso-8859-1 -*-
# Copyright (C) 2003, 2004 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."""

import linkcheck.dns.exception

class BadTTL(linkcheck.dns.exception.SyntaxError):
    pass

def from_text(text):
    """Convert the text form of a TTL to an integer.

    The BIND 8 units syntax for TTLs (e.g. '1w6d4h3m10s') is supported.

    @param text: the textual TTL
    @type text: string
    @raises linkcheck.dns.ttl.BadTTL: the TTL is not well-formed
    @rtype: int
    """

    if text.isdigit():
        return int(text)
    if not text[0].isdigit():
        raise BadTTL
    total = 0
    current = 0
    for c in text:
        if c.isdigit():
            current *= 10
            current += int(c)
        else:
            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
    if not current == 0:
        raise BadTTL, "trailing integer"
    return total