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|
| | """Common DNS Exceptions. |
| | |
| | Dnspython modules may also define their own exceptions, which will |
| | always be subclasses of ``DNSException``. |
| | """ |
| |
|
| |
|
| | from typing import Optional, Set |
| |
|
| |
|
| | 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: Optional[str] = None |
| | supp_kwargs: Set[str] = set() |
| | fmt: Optional[str] = None |
| |
|
| | 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() |
| | if self.msg is None: |
| | |
| | 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 |
| | ), f"following set of keyword args is required: {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)): |
| | |
| | fmtargs[kw] = list(map(str, data)) |
| | if len(fmtargs[kw]) == 1: |
| | |
| | fmtargs[kw] = fmtargs[kw].pop() |
| | else: |
| | fmtargs[kw] = data |
| | return fmtargs |
| |
|
| | def __str__(self): |
| | if self.kwargs and self.fmt: |
| | |
| | fmtargs = self._fmt_kwargs(**self.kwargs) |
| | return self.fmt.format(**fmtargs) |
| | else: |
| | |
| | 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:.3f} seconds" |
| |
|
| | |
| | |
| | def __init__(self, *args, **kwargs): |
| | super().__init__(*args, **kwargs) |
| |
|
| |
|
| | class UnsupportedAlgorithm(DNSException): |
| | """The DNSSEC algorithm is not supported.""" |
| |
|
| |
|
| | class AlgorithmKeyMismatch(UnsupportedAlgorithm): |
| | """The DNSSEC algorithm is not supported for the given key type.""" |
| |
|
| |
|
| | class ValidationFailure(DNSException): |
| | """The DNSSEC signature is invalid.""" |
| |
|
| |
|
| | class DeniedByPolicy(DNSException): |
| | """Denied by DNSSEC policy.""" |
| |
|
| |
|
| | 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 |
| |
|