170 lines
7.5 KiB
Python
170 lines
7.5 KiB
Python
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# Copyright 2012 Google Inc.
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#
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# Permission is hereby granted, free of charge, to any person obtaining a
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# copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish, dis-
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# tribute, sublicense, and/or sell copies of the Software, and to permit
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# persons to whom the Software is furnished to do so, subject to the fol-
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# lowing conditions:
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#
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# The above copyright notice and this permission notice shall be included
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# in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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# OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABIL-
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# ITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
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# SHALL THE AUTHOR BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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# WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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# IN THE SOFTWARE.
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import types
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from boto.gs.user import User
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from boto.exception import InvalidCorsError
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from xml.sax import handler
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# Relevant tags for the CORS XML document.
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CORS_CONFIG = 'CorsConfig'
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CORS = 'Cors'
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ORIGINS = 'Origins'
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ORIGIN = 'Origin'
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METHODS = 'Methods'
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METHOD = 'Method'
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HEADERS = 'ResponseHeaders'
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HEADER = 'ResponseHeader'
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MAXAGESEC = 'MaxAgeSec'
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class Cors(handler.ContentHandler):
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"""Encapsulates the CORS configuration XML document"""
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def __init__(self):
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# List of CORS elements found within a CorsConfig element.
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self.cors = []
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# List of collections (e.g. Methods, ResponseHeaders, Origins)
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# found within a CORS element. We use a list of lists here
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# instead of a dictionary because the collections need to be
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# preserved in the order in which they appear in the input XML
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# document (and Python dictionary keys are inherently unordered).
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# The elements on this list are two element tuples of the form
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# (collection name, [list of collection contents]).
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self.collections = []
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# Lists of elements within a collection. Again a list is needed to
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# preserve ordering but also because the same element may appear
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# multiple times within a collection.
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self.elements = []
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# Dictionary mapping supported collection names to element types
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# which may be contained within each.
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self.legal_collections = {
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ORIGINS : [ORIGIN],
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METHODS : [METHOD],
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HEADERS : [HEADER],
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MAXAGESEC: []
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}
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# List of supported element types within any collection, used for
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# checking validadity of a parsed element name.
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self.legal_elements = [ORIGIN, METHOD, HEADER]
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self.parse_level = 0
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self.collection = None
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self.element = None
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def validateParseLevel(self, tag, level):
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"""Verify parse level for a given tag."""
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if self.parse_level != level:
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raise InvalidCorsError('Invalid tag %s at parse level %d: ' %
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(tag, self.parse_level))
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def startElement(self, name, attrs, connection):
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"""SAX XML logic for parsing new element found."""
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if name == CORS_CONFIG:
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self.validateParseLevel(name, 0)
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self.parse_level += 1;
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elif name == CORS:
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self.validateParseLevel(name, 1)
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self.parse_level += 1;
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elif name in self.legal_collections:
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self.validateParseLevel(name, 2)
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self.parse_level += 1;
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self.collection = name
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elif name in self.legal_elements:
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self.validateParseLevel(name, 3)
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# Make sure this tag is found inside a collection tag.
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if self.collection is None:
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raise InvalidCorsError('Tag %s found outside collection' % name)
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# Make sure this tag is allowed for the current collection tag.
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if name not in self.legal_collections[self.collection]:
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raise InvalidCorsError('Tag %s not allowed in %s collection' %
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(name, self.collection))
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self.element = name
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else:
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raise InvalidCorsError('Unsupported tag ' + name)
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def endElement(self, name, value, connection):
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"""SAX XML logic for parsing new element found."""
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if name == CORS_CONFIG:
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self.validateParseLevel(name, 1)
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self.parse_level -= 1;
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elif name == CORS:
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self.validateParseLevel(name, 2)
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self.parse_level -= 1;
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# Terminating a CORS element, save any collections we found
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# and re-initialize collections list.
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self.cors.append(self.collections)
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self.collections = []
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elif name in self.legal_collections:
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self.validateParseLevel(name, 3)
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if name != self.collection:
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raise InvalidCorsError('Mismatched start and end tags (%s/%s)' %
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(self.collection, name))
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self.parse_level -= 1;
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if not self.legal_collections[name]:
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# If this collection doesn't contain any sub-elements, store
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# a tuple of name and this tag's element value.
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self.collections.append((name, value.strip()))
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else:
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# Otherwise, we're terminating a collection of sub-elements,
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# so store a tuple of name and list of contained elements.
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self.collections.append((name, self.elements))
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self.elements = []
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self.collection = None
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elif name in self.legal_elements:
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self.validateParseLevel(name, 3)
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# Make sure this tag is found inside a collection tag.
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if self.collection is None:
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raise InvalidCorsError('Tag %s found outside collection' % name)
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# Make sure this end tag is allowed for the current collection tag.
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if name not in self.legal_collections[self.collection]:
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raise InvalidCorsError('Tag %s not allowed in %s collection' %
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(name, self.collection))
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if name != self.element:
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raise InvalidCorsError('Mismatched start and end tags (%s/%s)' %
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(self.element, name))
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# Terminating an element tag, add it to the list of elements
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# for the current collection.
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self.elements.append((name, value.strip()))
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self.element = None
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else:
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raise InvalidCorsError('Unsupported end tag ' + name)
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def to_xml(self):
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"""Convert CORS object into XML string representation."""
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s = '<' + CORS_CONFIG + '>'
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for collections in self.cors:
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s += '<' + CORS + '>'
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for (collection, elements_or_value) in collections:
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assert collection is not None
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s += '<' + collection + '>'
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# If collection elements has type string, append atomic value,
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# otherwise, append sequence of values in named tags.
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if isinstance(elements_or_value, str):
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s += elements_or_value
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else:
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for (name, value) in elements_or_value:
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assert name is not None
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assert value is not None
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s += '<' + name + '>' + value + '</' + name + '>'
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s += '</' + collection + '>'
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s += '</' + CORS + '>'
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s += '</' + CORS_CONFIG + '>'
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return s
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