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