Package dns :: Package rdtypes :: Module mxbase
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Source Code for Module dns.rdtypes.mxbase

  1  # Copyright (C) 2003-2007, 2009-2011 Nominum, Inc. 
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 15   
 16  """MX-like base classes.""" 
 17   
 18  import cStringIO 
 19  import struct 
 20   
 21  import dns.exception 
 22  import dns.rdata 
 23  import dns.name 
 24   
25 -class MXBase(dns.rdata.Rdata):
26 """Base class for rdata that is like an MX record. 27 28 @ivar preference: the preference value 29 @type preference: int 30 @ivar exchange: the exchange name 31 @type exchange: dns.name.Name object""" 32 33 __slots__ = ['preference', 'exchange'] 34
35 - def __init__(self, rdclass, rdtype, preference, exchange):
36 super(MXBase, self).__init__(rdclass, rdtype) 37 self.preference = preference 38 self.exchange = exchange
39
40 - def to_text(self, origin=None, relativize=True, **kw):
41 exchange = self.exchange.choose_relativity(origin, relativize) 42 return '%d %s' % (self.preference, exchange)
43
44 - def from_text(cls, rdclass, rdtype, tok, origin = None, relativize = True):
50 51 from_text = classmethod(from_text) 52
53 - def to_wire(self, file, compress = None, origin = None):
54 pref = struct.pack("!H", self.preference) 55 file.write(pref) 56 self.exchange.to_wire(file, compress, origin)
57
58 - def to_digestable(self, origin = None):
59 return struct.pack("!H", self.preference) + \ 60 self.exchange.to_digestable(origin)
61
62 - def from_wire(cls, rdclass, rdtype, wire, current, rdlen, origin = None):
63 (preference, ) = struct.unpack('!H', wire[current : current + 2]) 64 current += 2 65 rdlen -= 2 66 (exchange, cused) = dns.name.from_wire(wire[: current + rdlen], 67 current) 68 if cused != rdlen: 69 raise dns.exception.FormError 70 if not origin is None: 71 exchange = exchange.relativize(origin) 72 return cls(rdclass, rdtype, preference, exchange)
73 74 from_wire = classmethod(from_wire) 75
76 - def choose_relativity(self, origin = None, relativize = True):
78
79 - def _cmp(self, other):
80 sp = struct.pack("!H", self.preference) 81 op = struct.pack("!H", other.preference) 82 v = cmp(sp, op) 83 if v == 0: 84 v = cmp(self.exchange, other.exchange) 85 return v
86
87 -class UncompressedMX(MXBase):
88 """Base class for rdata that is like an MX record, but whose name 89 is not compressed when converted to DNS wire format, and whose 90 digestable form is not downcased.""" 91
92 - def to_wire(self, file, compress = None, origin = None):
93 super(UncompressedMX, self).to_wire(file, None, origin)
94
95 - def to_digestable(self, origin = None):
96 f = cStringIO.StringIO() 97 self.to_wire(f, None, origin) 98 return f.getvalue()
99
100 -class UncompressedDowncasingMX(MXBase):
101 """Base class for rdata that is like an MX record, but whose name 102 is not compressed when convert to DNS wire format.""" 103
104 - def to_wire(self, file, compress = None, origin = None):
105 super(UncompressedDowncasingMX, self).to_wire(file, None, origin)
106