calibre-web/cps/cw_advocate/api.py

#
# Copyright 2015 Jordan Milne
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
# Source: https://github.com/JordanMilne/Advocate

"""
advocate.api
~~~~~~~~~~~~

This module implements the Requests API, largely a copy/paste from `requests`
itself.

:copyright: (c) 2015 by Jordan Milne.
:license: Apache2, see LICENSE for more details.

"""
from collections import OrderedDict
import hashlib
import pickle

from requests import Session as RequestsSession

# import cw_advocate
from .adapters import ValidatingHTTPAdapter
from .exceptions import MountDisabledException


class Session(RequestsSession):
    """Convenience wrapper around `requests.Session` set up for `advocate`ing"""

    __attrs__ = RequestsSession.__attrs__ + ["validator"]
    DEFAULT_VALIDATOR = None
    """
    User-replaceable default validator to use for all Advocate sessions,
    includes sessions created by advocate.get()
    """

    def __init__(self, *args, **kwargs):
        self.validator = kwargs.pop("validator", None) or self.DEFAULT_VALIDATOR
        adapter_kwargs = kwargs.pop("_adapter_kwargs", {})

        # `Session.__init__()` calls `mount()` internally, so we need to allow
        # it temporarily
        self.__mount_allowed = True
        RequestsSession.__init__(self, *args, **kwargs)

        # Drop any existing adapters
        self.adapters = OrderedDict()

        self.mount("http://", ValidatingHTTPAdapter(validator=self.validator, **adapter_kwargs))
        self.mount("https://", ValidatingHTTPAdapter(validator=self.validator, **adapter_kwargs))
        self.__mount_allowed = False

    def mount(self, *args, **kwargs):
        """Wrapper around `mount()` to prevent a protection bypass"""
        if self.__mount_allowed:
            super().mount(*args, **kwargs)
        else:
            raise MountDisabledException(
                "mount() is disabled to prevent protection bypasses"
            )


def session(*args, **kwargs):
    return Session(*args, **kwargs)


def request(method, url, **kwargs):
    """Constructs and sends a :class:`Request <Request>`.

    :param method: method for the new :class:`Request` object.
    :param url: URL for the new :class:`Request` object.
    :param params: (optional) Dictionary or bytes to be sent in the query string for the :class:`Request`.
    :param data: (optional) Dictionary, bytes, or file-like object to send in the body of the :class:`Request`.
    :param json: (optional) json data to send in the body of the :class:`Request`.
    :param headers: (optional) Dictionary of HTTP Headers to send with the :class:`Request`.
    :param cookies: (optional) Dict or CookieJar object to send with the :class:`Request`.
    :param files: (optional) Dictionary of ``'name': file-like-objects`` (or ``{'name': ('filename', fileobj)}``) for multipart encoding upload.
    :param auth: (optional) Auth tuple to enable Basic/Digest/Custom HTTP Auth.
    :param timeout: (optional) How long to wait for the server to send data
        before giving up, as a float, or a (`connect timeout, read timeout
        <user/advanced.html#timeouts>`_) tuple.
    :type timeout: float or tuple
    :param allow_redirects: (optional) Boolean. Set to True if POST/PUT/DELETE redirect following is allowed.
    :type allow_redirects: bool
    :param proxies: (optional) Dictionary mapping protocol to the URL of the proxy.
    :param verify: (optional) if ``True``, the SSL cert will be verified. A CA_BUNDLE path can also be provided.
    :param stream: (optional) if ``False``, the response content will be immediately downloaded.
    :param cert: (optional) if String, path to ssl client cert file (.pem). If Tuple, ('cert', 'key') pair.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    validator = kwargs.pop("validator", None)
    with Session(validator=validator) as sess:
        response = sess.request(method=method, url=url, **kwargs)
    return response


def get(url, **kwargs):
    """Sends a GET request.

    :param url: URL for the new :class:`Request` object.
    :param **kwargs: Optional arguments that ``request`` takes.
    :return: :class:`Response <Response>` object
    :rtype: requests.Response
    """

    kwargs.setdefault('allow_redirects', True)
    return request('get', url, **kwargs)


class RequestsAPIWrapper:
    """Provides a `requests.api`-like interface with a specific validator"""

    # Due to how the classes are dynamically constructed pickling may not work
    # correctly unless loaded within the same interpreter instance.
    # Enable at your peril.
    SUPPORT_WRAPPER_PICKLING = False

    def __init__(self, validator):
        # Do this here to avoid circular import issues
        try:
            from .futures import FuturesSession
            have_requests_futures = True
        except ImportError as e:
            have_requests_futures = False

        self.validator = validator
        outer_self = self

        class _WrappedSession(Session):
            """An `advocate.Session` that uses the wrapper's blacklist

            the wrapper is meant to be a transparent replacement for `requests`,
            so people should be able to subclass `wrapper.Session` and still
            get the desired validation behaviour
            """
            DEFAULT_VALIDATOR = outer_self.validator

        self._make_wrapper_cls_global(_WrappedSession)

        if have_requests_futures:

            class _WrappedFuturesSession(FuturesSession):
                """Like _WrappedSession, but for `FuturesSession`s"""
                DEFAULT_VALIDATOR = outer_self.validator
            self._make_wrapper_cls_global(_WrappedFuturesSession)

            self.FuturesSession = _WrappedFuturesSession

        self.request = self._default_arg_wrapper(request)
        self.get = self._default_arg_wrapper(get)
        self.Session = _WrappedSession

    def __getattr__(self, item):
        # This class is meant to mimic the requests base module, so if we don't
        # have this attribute, it might be on the base module (like the Request
        # class, etc.)
        try:
            return object.__getattribute__(self, item)
        except AttributeError:
            from . import cw_advocate
            return getattr(cw_advocate, item)

    def _default_arg_wrapper(self, fun):
        def wrapped_func(*args, **kwargs):
            kwargs.setdefault("validator", self.validator)
            return fun(*args, **kwargs)
        return wrapped_func

    def _make_wrapper_cls_global(self, cls):
        if not self.SUPPORT_WRAPPER_PICKLING:
            return
        # Gnarly, but necessary to give pickle a consistent module-level
        # reference for each wrapper.
        wrapper_hash = hashlib.sha256(pickle.dumps(self)).hexdigest()
        cls.__name__ = "_".join((cls.__name__, wrapper_hash))
        cls.__qualname__ = ".".join((__name__, cls.__name__))
        if not globals().get(cls.__name__):
            globals()[cls.__name__] = cls


__all__ = (
    "get",
    "request",
    "session",
    "Session",
    "RequestsAPIWrapper",
)