lib/dnspython/dns/rcode.py

   1 # Copyright (C) 2001-2007, 2009-2011 Nominum, Inc.
   2 #
   3 # Permission to use, copy, modify, and distribute this software and its
   4 # documentation for any purpose with or without fee is hereby granted,
   5 # provided that the above copyright notice and this permission notice
   6 # appear in all copies.
   7 #
   8 # THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
   9 # WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  10 # MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
  11 # ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  12 # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  13 # ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  14 # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  15
  16 """DNS Result Codes."""
  17
  18 import dns.exception
  19
  20 NOERROR = 0
  21 FORMERR = 1
  22 SERVFAIL = 2
  23 NXDOMAIN = 3
  24 NOTIMP = 4
  25 REFUSED = 5
  26 YXDOMAIN = 6
  27 YXRRSET = 7
  28 NXRRSET = 8
  29 NOTAUTH = 9
  30 NOTZONE = 10
  31 BADVERS = 16
  32
  33 _by_text = {
  34     'NOERROR' : NOERROR,
  35     'FORMERR' : FORMERR,
  36     'SERVFAIL' : SERVFAIL,
  37     'NXDOMAIN' : NXDOMAIN,
  38     'NOTIMP' : NOTIMP,
  39     'REFUSED' : REFUSED,
  40     'YXDOMAIN' : YXDOMAIN,
  41     'YXRRSET' : YXRRSET,
  42     'NXRRSET' : NXRRSET,
  43     'NOTAUTH' : NOTAUTH,
  44     'NOTZONE' : NOTZONE,
  45     'BADVERS' : BADVERS
  46 }
  47
  48 # We construct the inverse mapping programmatically to ensure that we
  49 # cannot make any mistakes (e.g. omissions, cut-and-paste errors) that
  50 # would cause the mapping not to be a true inverse.
  51
  52 _by_value = dict([(y, x) for x, y in _by_text.iteritems()])
  53
  54
  55 class UnknownRcode(dns.exception.DNSException):
  56     """Raised if an rcode is unknown."""
  57     pass
  58
  59 def from_text(text):
  60     """Convert text into an rcode.
  61
  62     @param text: the texual rcode
  63     @type text: string
  64     @raises UnknownRcode: the rcode is unknown
  65     @rtype: int
  66     """
  67
  68     if text.isdigit():
  69         v = int(text)
  70         if v >= 0 and v <= 4095:
  71             return v
  72     v = _by_text.get(text.upper())
  73     if v is None:
  74         raise UnknownRcode
  75     return v
  76
  77 def from_flags(flags, ednsflags):
  78     """Return the rcode value encoded by flags and ednsflags.
  79
  80     @param flags: the DNS flags
  81     @type flags: int
  82     @param ednsflags: the EDNS flags
  83     @type ednsflags: int
  84     @raises ValueError: rcode is < 0 or > 4095
  85     @rtype: int
  86     """
  87
  88     value = (flags & 0x000f) | ((ednsflags >> 20) & 0xff0)
  89     if value < 0 or value > 4095:
  90         raise ValueError('rcode must be >= 0 and <= 4095')
  91     return value
  92
  93 def to_flags(value):
  94     """Return a (flags, ednsflags) tuple which encodes the rcode.
  95
  96     @param value: the rcode
  97     @type value: int
  98     @raises ValueError: rcode is < 0 or > 4095
  99     @rtype: (int, int) tuple
 100     """
 101
 102     if value < 0 or value > 4095:
 103         raise ValueError('rcode must be >= 0 and <= 4095')
 104     v = value & 0xf
 105     ev = long(value & 0xff0) << 20
 106     return (v, ev)
 107
 108 def to_text(value):
 109     """Convert rcode into text.
 110
 111     @param value: the rcode
 112     @type value: int
 113     @rtype: string
 114     """
 115
 116     text = _by_value.get(value)
 117     if text is None:
 118         text = str(value)
 119     return text