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169 lines
5.8 KiB
169 lines
5.8 KiB
# Copyright (C) Dnspython Contributors, see LICENSE for text of ISC license |
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# Copyright (C) 2003-2017 Nominum, Inc. |
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# |
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# Permission to use, copy, modify, and distribute this software and its |
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# documentation for any purpose with or without fee is hereby granted, |
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# provided that the above copyright notice and this permission notice |
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# appear in all copies. |
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# |
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# THE SOFTWARE IS PROVIDED "AS IS" AND NOMINUM DISCLAIMS ALL WARRANTIES |
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# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
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# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL NOMINUM BE LIABLE FOR |
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# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
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# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
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# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT |
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# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
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"""Common DNS Exceptions. |
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Dnspython modules may also define their own exceptions, which will |
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always be subclasses of ``DNSException``. |
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""" |
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from typing import Optional, Set |
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class DNSException(Exception): |
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"""Abstract base class shared by all dnspython exceptions. |
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It supports two basic modes of operation: |
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a) Old/compatible mode is used if ``__init__`` was called with |
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empty *kwargs*. In compatible mode all *args* are passed |
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to the standard Python Exception class as before and all *args* are |
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printed by the standard ``__str__`` implementation. Class variable |
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``msg`` (or doc string if ``msg`` is ``None``) is returned from ``str()`` |
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if *args* is empty. |
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b) New/parametrized mode is used if ``__init__`` was called with |
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non-empty *kwargs*. |
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In the new mode *args* must be empty and all kwargs must match |
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those set in class variable ``supp_kwargs``. All kwargs are stored inside |
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``self.kwargs`` and used in a new ``__str__`` implementation to construct |
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a formatted message based on the ``fmt`` class variable, a ``string``. |
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In the simplest case it is enough to override the ``supp_kwargs`` |
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and ``fmt`` class variables to get nice parametrized messages. |
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""" |
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msg: Optional[str] = None # non-parametrized message |
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supp_kwargs: Set[str] = set() # accepted parameters for _fmt_kwargs (sanity check) |
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fmt: Optional[str] = None # message parametrized with results from _fmt_kwargs |
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def __init__(self, *args, **kwargs): |
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self._check_params(*args, **kwargs) |
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if kwargs: |
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# This call to a virtual method from __init__ is ok in our usage |
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self.kwargs = self._check_kwargs(**kwargs) # lgtm[py/init-calls-subclass] |
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self.msg = str(self) |
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else: |
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self.kwargs = dict() # defined but empty for old mode exceptions |
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if self.msg is None: |
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# doc string is better implicit message than empty string |
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self.msg = self.__doc__ |
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if args: |
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super().__init__(*args) |
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else: |
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super().__init__(self.msg) |
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def _check_params(self, *args, **kwargs): |
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"""Old exceptions supported only args and not kwargs. |
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For sanity we do not allow to mix old and new behavior.""" |
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if args or kwargs: |
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assert bool(args) != bool( |
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kwargs |
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), "keyword arguments are mutually exclusive with positional args" |
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def _check_kwargs(self, **kwargs): |
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if kwargs: |
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assert ( |
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set(kwargs.keys()) == self.supp_kwargs |
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), "following set of keyword args is required: %s" % (self.supp_kwargs) |
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return kwargs |
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def _fmt_kwargs(self, **kwargs): |
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"""Format kwargs before printing them. |
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Resulting dictionary has to have keys necessary for str.format call |
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on fmt class variable. |
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""" |
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fmtargs = {} |
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for kw, data in kwargs.items(): |
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if isinstance(data, (list, set)): |
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# convert list of <someobj> to list of str(<someobj>) |
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fmtargs[kw] = list(map(str, data)) |
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if len(fmtargs[kw]) == 1: |
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# remove list brackets [] from single-item lists |
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fmtargs[kw] = fmtargs[kw].pop() |
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else: |
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fmtargs[kw] = data |
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return fmtargs |
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def __str__(self): |
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if self.kwargs and self.fmt: |
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# provide custom message constructed from keyword arguments |
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fmtargs = self._fmt_kwargs(**self.kwargs) |
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return self.fmt.format(**fmtargs) |
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else: |
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# print *args directly in the same way as old DNSException |
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return super().__str__() |
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class FormError(DNSException): |
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"""DNS message is malformed.""" |
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class SyntaxError(DNSException): |
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"""Text input is malformed.""" |
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class UnexpectedEnd(SyntaxError): |
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"""Text input ended unexpectedly.""" |
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class TooBig(DNSException): |
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"""The DNS message is too big.""" |
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class Timeout(DNSException): |
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"""The DNS operation timed out.""" |
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supp_kwargs = {"timeout"} |
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fmt = "The DNS operation timed out after {timeout:.3f} seconds" |
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# We do this as otherwise mypy complains about unexpected keyword argument |
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# idna_exception |
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def __init__(self, *args, **kwargs): |
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super().__init__(*args, **kwargs) |
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class UnsupportedAlgorithm(DNSException): |
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"""The DNSSEC algorithm is not supported.""" |
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class AlgorithmKeyMismatch(UnsupportedAlgorithm): |
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"""The DNSSEC algorithm is not supported for the given key type.""" |
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class ValidationFailure(DNSException): |
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"""The DNSSEC signature is invalid.""" |
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class DeniedByPolicy(DNSException): |
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"""Denied by DNSSEC policy.""" |
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class ExceptionWrapper: |
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def __init__(self, exception_class): |
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self.exception_class = exception_class |
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def __enter__(self): |
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return self |
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def __exit__(self, exc_type, exc_val, exc_tb): |
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if exc_type is not None and not isinstance(exc_val, self.exception_class): |
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raise self.exception_class(str(exc_val)) from exc_val |
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return False
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