1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license
# Copyright (C) 2003-2017 Nominum, Inc.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose with or without fee is hereby granted,
# provided that the above copyright notice and this permission notice
# appear in all copies.
#
# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES
# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR
# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
"""Common DNS Exceptions.
Dnspython modules may also define their own exceptions, which will
always be subclasses of ``DNSException``.
"""
class DNSException(Exception):
"""Abstract base class shared by all dnspython exceptions.
It supports two basic modes of operation:
a) Old/compatible mode is used if ``__init__`` was called with
empty *kwargs*. In compatible mode all *args* are passed
to the standard Python Exception class as before and all *args* are
printed by the standard ``__str__`` implementation. Class variable
``msg`` (or doc string if ``msg`` is ``None``) is returned from ``str()``
if *args* is empty.
b) New/parametrized mode is used if ``__init__`` was called with
non-empty *kwargs*.
In the new mode *args* must be empty and all kwargs must match
those set in class variable ``supp_kwargs``. All kwargs are stored inside
``self.kwargs`` and used in a new ``__str__`` implementation to construct
a formatted message based on the ``fmt`` class variable, a ``string``.
In the simplest case it is enough to override the ``supp_kwargs``
and ``fmt`` class variables to get nice parametrized messages.
"""
msg = None # non-parametrized message
supp_kwargs = set() # accepted parameters for _fmt_kwargs (sanity check)
fmt = None # message parametrized with results from _fmt_kwargs
def __init__(self, *args, **kwargs):
self._check_params(*args, **kwargs)
if kwargs:
self.kwargs = self._check_kwargs(**kwargs)
self.msg = str(self)
else:
self.kwargs = dict() # defined but empty for old mode exceptions
if self.msg is None:
# doc string is better implicit message than empty string
self.msg = self.__doc__
if args:
super().__init__(*args)
else:
super().__init__(self.msg)
def _check_params(self, *args, **kwargs):
"""Old exceptions supported only args and not kwargs.
For sanity we do not allow to mix old and new behavior."""
if args or kwargs:
assert bool(args) != bool(kwargs), \
'keyword arguments are mutually exclusive with positional args'
def _check_kwargs(self, **kwargs):
if kwargs:
assert set(kwargs.keys()) == self.supp_kwargs, \
'following set of keyword args is required: %s' % (
self.supp_kwargs)
return kwargs
def _fmt_kwargs(self, **kwargs):
"""Format kwargs before printing them.
Resulting dictionary has to have keys necessary for str.format call
on fmt class variable.
"""
fmtargs = {}
for kw, data in kwargs.items():
if isinstance(data, (list, set)):
# convert list of <someobj> to list of str(<someobj>)
fmtargs[kw] = list(map(str, data))
if len(fmtargs[kw]) == 1:
# remove list brackets [] from single-item lists
fmtargs[kw] = fmtargs[kw].pop()
else:
fmtargs[kw] = data
return fmtargs
def __str__(self):
if self.kwargs and self.fmt:
# provide custom message constructed from keyword arguments
fmtargs = self._fmt_kwargs(**self.kwargs)
return self.fmt.format(**fmtargs)
else:
# print *args directly in the same way as old DNSException
return super().__str__()
class FormError(DNSException):
"""DNS message is malformed."""
class SyntaxError(DNSException):
"""Text input is malformed."""
class UnexpectedEnd(SyntaxError):
"""Text input ended unexpectedly."""
class TooBig(DNSException):
"""The DNS message is too big."""
class Timeout(DNSException):
"""The DNS operation timed out."""
supp_kwargs = {'timeout'}
fmt = "The DNS operation timed out after {timeout} seconds"
class ExceptionWrapper:
def __init__(self, exception_class):
self.exception_class = exception_class
def __enter__(self):
return self
def __exit__(self, exc_type, exc_val, exc_tb):
if exc_type is not None and not isinstance(exc_val,
self.exception_class):
raise self.exception_class(str(exc_val)) from exc_val
return False
|
