lib/dnspython/dns/ttl.py

   1 # Copyright (C) 2003-2007, 2009-2011 Nominum, Inc.
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   9 # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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  14 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15
  16 """DNS TTL conversion."""
  17
  18 import dns.exception
  19
  20 class BadTTL(dns.exception.SyntaxError):
  21     pass
  22
  23 def from_text(text):
  24     """Convert the text form of a TTL to an integer.
  25
  26     The BIND 8 units syntax for TTLs (e.g. '1w6d4h3m10s') is supported.
  27
  28     @param text: the textual TTL
  29     @type text: string
  30     @raises dns.ttl.BadTTL: the TTL is not well-formed
  31     @rtype: int
  32     """
  33
  34     if text.isdigit():
  35         total = long(text)
  36     else:
  37         if not text[0].isdigit():
  38             raise BadTTL
  39         total = 0L
  40         current = 0L
  41         for c in text:
  42             if c.isdigit():
  43                 current *= 10
  44                 current += long(c)
  45             else:
  46                 c = c.lower()
  47                 if c == 'w':
  48                     total += current * 604800L
  49                 elif c == 'd':
  50                     total += current * 86400L
  51                 elif c == 'h':
  52                     total += current * 3600L
  53                 elif c == 'm':
  54                     total += current * 60L
  55                 elif c == 's':
  56                     total += current
  57                 else:
  58                     raise BadTTL("unknown unit '%s'" % c)
  59                 current = 0
  60         if not current == 0:
  61             raise BadTTL("trailing integer")
  62     if total < 0L or total > 2147483647L:
  63         raise BadTTL("TTL should be between 0 and 2^31 - 1 (inclusive)")
  64     return total