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,
7# provided that the above copyright notice and this permission notice
8# appear in all copies.
9#
10# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
11# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
12# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
13# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
14# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
15# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
16# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
17
18"""TXT-like base class."""
19
20import struct
21
22import dns.exception
23import dns.rdata
24import dns.tokenizer
25from dns._compat import binary_type, string_types
26
27
28class 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