117 lines
4.8 KiB
Python
117 lines
4.8 KiB
Python
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# -*- coding: utf-8 -*-
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"""
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flask_cors
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~~~~
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Flask-CORS is a simple extension to Flask allowing you to support cross
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origin resource sharing (CORS) using a simple decorator.
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:copyright: (c) 2014 by Cory Dolphin.
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:license: MIT, see LICENSE for more details.
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"""
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from flask import request
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from .core import *
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class CORS(object):
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'''
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Initializes Cross Origin Resource sharing for the application. The
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arguments are identical to :py:func:`cross_origin`, with the
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addition of a `resources` parameter. The resources parameter
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defines a series of regular expressions for resource paths to match
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and optionally, the associated options
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to be applied to the particular resource. These options are
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identical to the arguments to :py:func:`cross_origin`.
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The settings for CORS are determined in the following order:
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Resource level settings (e.g when passed as a dictionary)
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Keyword argument settings
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App level configuration settings (e.g. CORS_*)
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Default settings
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Note: as it is possible for multiple regular expressions to match a
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resource path, the regular expressions are first sorted by length,
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from longest to shortest, in order to attempt to match the most
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specific regular expression. This allows the definition of a
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number of specific resource options, with a wildcard fallback
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for all other resources.
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:param resources: the series of regular expression and (optionally)
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associated CORS options to be applied to the given resource path.
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If the argument is a dictionary, it is expected to be of the form:
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regexp : dict_of_options
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If the argument is a list, it is expected to be a list of regular
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expressions, for which the app-wide configured options are applied.
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If the argument is a string, it is expected to be a regular
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expression for which the app-wide configured options are applied.
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Default :'*'
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:type resources: dict, iterable or string
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'''
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def __init__(self, app=None, **kwargs):
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self._options = kwargs
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if app is not None:
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self.init_app(app, **kwargs)
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def init_app(self, app, **kwargs):
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# The resources and options may be specified in the App Config, the CORS constructor
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# or the kwargs to the call to init_app.
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options = get_cors_options(app, self._options, kwargs)
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# Flatten our resources into a list of the form
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# (pattern_or_regexp, dictionary_of_options)
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resources = parse_resources(options.get('resources'))
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# Compute the options for each resource by combining the options from
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# the app's configuration, the constructor, the kwargs to init_app, and
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# finally the options specified in the resources dictionary.
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resources = [
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(pattern, get_cors_options(app, options, opts))
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for (pattern, opts) in resources
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]
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# Create a human readable form of these resources by converting the compiled
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# regular expressions into strings.
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resources_human = dict([(get_regexp_pattern(pattern), opts) for (pattern,opts) in resources])
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getLogger(app).info("Configuring CORS with resources: %s", resources_human)
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def cors_after_request(resp):
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'''
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The actual after-request handler, retains references to the
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the options, and definitions of resources through a closure.
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'''
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# If CORS headers are set in a view decorator, pass
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if resp.headers.get(ACL_ORIGIN):
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debugLog('CORS have been already evaluated, skipping')
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return resp
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for res_regex, res_options in resources:
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if try_match(request.path, res_regex):
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debugLog("Request to '%s' matches CORS resource '%s'. Using options: %s",
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request.path, get_regexp_pattern(res_regex), res_options)
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set_cors_headers(resp, res_options)
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break
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else:
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debugLog('No CORS rule matches')
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return resp
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app.after_request(cors_after_request)
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# Wrap exception handlers with cross_origin
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# These error handlers will still respect the behavior of the route
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if options.get('intercept_exceptions', True):
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def _after_request_decorator(f):
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def wrapped_function(*args, **kwargs):
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return cors_after_request(app.make_response(f(*args, **kwargs)))
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return wrapped_function
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app.handle_exception = _after_request_decorator(
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app.handle_exception)
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app.handle_user_exception = _after_request_decorator(
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app.handle_user_exception)
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