141 lines
5.3 KiB
Python
141 lines
5.3 KiB
Python
# -*- coding: utf-8 -*-
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""" Manages the storage and lifecycle of non-literal domains and contexts
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(and potentially other structures) which have to be evaluated with client data,
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but still need to be safely round-tripped to and from the browser (and thus
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can't be sent there themselves).
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"""
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import binascii
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import hashlib
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import simplejson.decoder
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import simplejson.encoder
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__all__ = ['Domain', 'Context', 'NonLiteralEncoder, non_literal_decoder']
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#: 48 bits should be sufficient to have almost no chance of collision
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#: with a million hashes, according to hg@67081329d49a
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SHORT_HASH_BYTES_SIZE = 6
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class NonLiteralEncoder(simplejson.encoder.JSONEncoder):
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def default(self, object):
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if isinstance(object, Domain):
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return {
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'__ref': 'domain',
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'__id': object.key
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}
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elif isinstance(object, Context):
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return {
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'__ref': 'context',
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'__id': object.key
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}
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return super(NonLiteralEncoder, self).default(object)
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def non_literal_decoder(dct):
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""" Decodes JSON dicts into :class:`Domain` and :class:`Context` based on
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magic attribute tags.
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Also handles private context section for the domain or section via the
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``own_values`` dict key.
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"""
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if '__ref' in dct:
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if dct['__ref'] == 'domain':
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domain = Domain(None, key=dct['__id'])
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if 'own_values' in dct:
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domain.own = dct['own_values']
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return domain
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elif dct['__ref'] == 'context':
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context = Context(None, key=dct['__id'])
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if 'own_values' in dct:
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context.own = dct['own_values']
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return context
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return dct
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class Domain(object):
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def __init__(self, session, domain_string=None, key=None):
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""" Uses session information to store the domain string and map it to a
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domain key, which can be safely round-tripped to the client.
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If initialized with a domain string, will generate a key for that
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string and store the domain string out of the way. When initialized
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with a key, considers this key is a reference to an existing domain
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string.
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:param session: the OpenERP Session to use when evaluating the domain
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:type session: openerpweb.openerpweb.OpenERPSession
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:param str domain_string: a non-literal domain in string form
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:param str key: key used to retrieve the domain string
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"""
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if domain_string and key:
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raise ValueError("A nonliteral domain can not take both a key "
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"and a domain string")
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self.session = session
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self.own = {}
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if domain_string:
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self.key = binascii.hexlify(
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hashlib.sha256(domain_string).digest()[:SHORT_HASH_BYTES_SIZE])
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self.session.domains_store[self.key] = domain_string
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elif key:
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self.key = key
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def get_domain_string(self):
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""" Retrieves the domain string linked to this non-literal domain in
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the provided session.
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"""
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return self.session.domains_store[self.key]
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def evaluate(self, context=None):
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""" Forces the evaluation of the linked domain, using the provided
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context (as well as the session's base context), and returns the
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evaluated result.
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"""
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ctx = self.session.evaluation_context(context)
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if self.own:
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ctx.update(self.own)
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return eval(self.get_domain_string(), ctx)
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class Context(object):
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def __init__(self, session, context_string=None, key=None):
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""" Uses session information to store the context string and map it to
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a key (stored in a secret location under a secret mountain), which can
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be safely round-tripped to the client.
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If initialized with a context string, will generate a key for that
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string and store the context string out of the way. When initialized
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with a key, considers this key is a reference to an existing context
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string.
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:param session: the OpenERP Session to use when evaluating the context
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:type session: openerpweb.openerpweb.OpenERPSession
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:param str context_string: a non-literal context in string form
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:param str key: key used to retrieve the context string
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"""
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if context_string and key:
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raise ValueError("A nonliteral domain can not take both a key "
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"and a domain string")
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self.session = session
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self.own = {}
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if context_string:
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self.key = binascii.hexlify(
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hashlib.sha256(context_string).digest()[:SHORT_HASH_BYTES_SIZE])
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self.session.contexts_store[self.key] = context_string
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elif key:
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self.key = key
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def get_context_string(self):
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""" Retrieves the context string linked to this non-literal context in
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the provided session.
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"""
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return self.session.contexts_store[self.key]
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def evaluate(self, context=None):
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""" Forces the evaluation of the linked context, using the provided
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context (as well as the session's base context), and returns the
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evaluated result.
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"""
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ctx = self.session.evaluation_context(context)
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if self.own:
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ctx.update(self.own)
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return eval(self.get_context_string(),
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ctx)
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