third_party/dnspython/dns/rdtypes/txtbase.py

   1 # Copyright (C) 2006, 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
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   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
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  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 """TXT-like base class."""
  17
  18 import dns.exception
  19 import dns.rdata
  20 import dns.tokenizer
  21
  22 class TXTBase(dns.rdata.Rdata):
  23     """Base class for rdata that is like a TXT record
  24
  25     @ivar strings: the text strings
  26     @type strings: list of string
  27     @see: RFC 1035"""
  28
  29     __slots__ = ['strings']
  30
  31     def __init__(self, rdclass, rdtype, strings):
  32         super(TXTBase, self).__init__(rdclass, rdtype)
  33         if isinstance(strings, str):
  34             strings = [ strings ]
  35         self.strings = strings[:]
  36
  37     def to_text(self, origin=None, relativize=True, **kw):
  38         txt = ''
  39         prefix = ''
  40         for s in self.strings:
  41             txt += '%s"%s"' % (prefix, dns.rdata._escapify(s))
  42             prefix = ' '
  43         return txt
  44
  45     def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
  46         strings = []
  47         while 1:
  48             token = tok.get().unescape()
  49             if token.is_eol_or_eof():
  50                 break
  51             if not (token.is_quoted_string() or token.is_identifier()):
  52                 raise dns.exception.SyntaxError("expected a string")
  53             if len(token.value) > 255:
  54                 raise dns.exception.SyntaxError("string too long")
  55             strings.append(token.value)
  56         if len(strings) == 0:
  57             raise dns.exception.UnexpectedEnd
  58         return cls(rdclass, rdtype, strings)
  59
  60     from_text = classmethod(from_text)
  61
  62     def to_wire(self, file, compress = None, origin = None):
  63         for s in self.strings:
  64             l = len(s)
  65             assert l < 256
  66             byte = chr(l)
  67             file.write(byte)
  68             file.write(s)
  69
  70     def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
  71         strings = []
  72         while rdlen > 0:
  73             l = ord(wire[current])
  74             current += 1
  75             rdlen -= 1
  76             if l > rdlen:
  77                 raise dns.exception.FormError
  78             s = wire[current : current + l].unwrap()
  79             current += l
  80             rdlen -= l
  81             strings.append(s)
  82         return cls(rdclass, rdtype, strings)
  83
  84     from_wire = classmethod(from_wire)
  85
  86     def _cmp(self, other):
  87         return cmp(self.strings, other.strings)