Source Code for Module dns.rdtypes.txtbase

 1  # Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license 
 2   
 3  # Copyright (C) 2006-2017 Nominum, Inc. 
 4  # 
 5  # Permission to use, copy, modify, and distribute this software and its 
 6  # documentation for any purpose with or without fee is hereby granted, 
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14  # WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 
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16  # OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 
17   
18  """TXT-like base class.""" 
19   
20  import struct 
21   
22  import dns.exception 
23  import dns.rdata 
24  import dns.tokenizer 
25  from dns._compat import binary_type, string_types 
26   
27   
28 -class TXTBase(dns.rdata.Rdata): 
29   
30      """Base class for rdata that is like a TXT record 
31   
32      @ivar strings: the strings 
33      @type strings: list of binary 
34      @see: RFC 1035""" 
35   
36      __slots__ = ['strings'] 
37   
38 -    def __init__(self, rdclass, rdtype, strings): 
39          super(TXTBase, self).__init__(rdclass, rdtype) 
40          if isinstance(strings, binary_type) or \ 
41             isinstance(strings, string_types): 
42              strings = [strings] 
43          self.strings = [] 
44          for string in strings: 
45              if isinstance(string, string_types): 
46                  string = string.encode() 
47              self.strings.append(string) 
48   
49 -    def to_text(self, origin=None, relativize=True, **kw): 
50          txt = '' 
51          prefix = '' 
52          for s in self.strings: 
53              txt += '{}"{}"'.format(prefix, dns.rdata._escapify(s)) 
54              prefix = ' ' 
55          return txt 
56   
57      @classmethod 
58 -    def from_text(cls, rdclass, rdtype, tok, origin=None, relativize=True): 
59          strings = [] 
60          while 1: 
61              token = tok.get().unescape() 
62              if token.is_eol_or_eof(): 
63                  break 
64              if not (token.is_quoted_string() or token.is_identifier()): 
65                  raise dns.exception.SyntaxError("expected a string") 
66              if len(token.value) > 255: 
67                  raise dns.exception.SyntaxError("string too long") 
68              value = token.value 
69              if isinstance(value, binary_type): 
70                  strings.append(value) 
71              else: 
72                  strings.append(value.encode()) 
73          if len(strings) == 0: 
74              raise dns.exception.UnexpectedEnd 
75          return cls(rdclass, rdtype, strings) 
76   
77 -    def to_wire(self, file, compress=None, origin=None): 
78          for s in self.strings: 
79              l = len(s) 
80              assert l < 256 
81              file.write(struct.pack('!B', l)) 
82              file.write(s) 
83   
84      @classmethod 
85 -    def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin=None): 
86          strings = [] 
87          while rdlen > 0: 
88              l = wire[current] 
89              current += 1 
90              rdlen -= 1 
91              if l > rdlen: 
92                  raise dns.exception.FormError 
93              s = wire[current: current + l].unwrap() 
94              current += l 
95              rdlen -= l 
96              strings.append(s) 
97          return cls(rdclass, rdtype, strings) 
98