103 lines
3.7 KiB
Python
103 lines
3.7 KiB
Python
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# Copyright 2020 The TensorFlow Authors. All Rights Reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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# ==============================================================================
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"""Experimental framework for authentication in TensorBoard."""
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import abc
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class AuthProvider(metaclass=abc.ABCMeta):
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"""Authentication provider for a specific kind of credential."""
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def authenticate(self, environ):
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"""Produce an opaque auth token from a WSGI request environment.
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Args:
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environ: A WSGI environment `dict`; see PEP 3333.
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Returns:
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A Python object representing an auth token. The representation
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and semantics depend on the particular `AuthProvider`
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implementation.
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Raises:
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Exception: Any error, usually `tensorboard.errors.PublicError`
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subclasses (like `PermissionDenied`) but also possibly a
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custom error type that should propagate to a WSGI middleware
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for effecting a redirect-driven auth flow.
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"""
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pass
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class AuthContext:
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"""Authentication context within the scope of a single request.
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Auth providers are keyed within an `AuthContext` by arbitrary
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unique keys. It may often make sense for the key used for an
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auth provider to simply be that provider's type object.
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"""
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def __init__(self, providers, environ):
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"""Create an auth context.
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Args:
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providers: A mapping from provider keys (opaque values) to
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`AuthProvider` implementations.
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environ: A WSGI environment (see PEP 3333).
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"""
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self._environ = environ
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self._providers = providers
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self._cache = {}
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@classmethod
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def empty(cls):
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"""Create an auth context with no registered providers.
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Returns:
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A new `AuthContext` value for which any call to `get` will
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fail with a `KeyError`.
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"""
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# Use an empty dict for the environ. This is not a valid WSGI
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# environment, but it doesn't matter because it's never used.
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return cls({}, {})
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def get(self, provider_key):
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"""Get an auth token from the auth provider with the given key.
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If successful, the result will be cached on this auth context.
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If unsuccessful, nothing will be cached, so a future call will
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invoke the underlying `AuthProvider.authenticate` method again.
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This method is not thread-safe. If multiple threads share an
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auth context for a single request, then they must synchronize
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externally when calling this method.
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Returns:
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The result of `provider.authenticate(...)` for the auth
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provider specified by `provider_key`.
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Raises:
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KeyError: If the given `provider_key` does not correspond to
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any registered `AuthProvider`.
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Exception: As raised by the underlying `AuthProvider`.
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"""
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provider = self._providers[provider_key]
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sentinel = object()
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value = self._cache.get(provider_key, sentinel)
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if value is not sentinel:
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return value
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value = provider.authenticate(self._environ)
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self._cache[provider_key] = value
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return value
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