2020-10-27 00:50:13 +08:00
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# frozen_string_literal: true
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2018-05-12 04:48:25 +08:00
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#
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# Copyright (C) 2018 - present Instructure, Inc.
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#
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# This file is part of Canvas.
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#
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# Canvas is free software: you can redistribute it and/or modify it under
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# the terms of the GNU Affero General Public License as published by the Free
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# Software Foundation, version 3 of the License.
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#
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# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
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# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
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# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
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# details.
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#
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# You should have received a copy of the GNU Affero General Public License along
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# with this program. If not, see <http://www.gnu.org/licenses/>.
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# This file contains routines for creating IDs used for graders and submission
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# in place of the objects' actual IDs for Anonymous Moderated Marking.
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# The IDs are 5 characters long and in base58 format. These IDs are meant to be
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# unique across the graders or submissions for a given assignment: a grader
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# for an assignment, for example, can be referenced by their "anonymous" ID
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# for that specific assignment so that their default ID is concealed.
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module Anonymity
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# Returns a unique short id to be used as an anonymous ID. If the
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# generated short id is already in use, loop until an available
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# one is generated.
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# This method will throw a unique constraint error from the
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# database if it has used all unique ids.
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# An optional argument of existing_ids can be supplied
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# to customize the handling of existing ids. E.g. bulk
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# generation of anonymous ids where you wouldn't want to
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# continuously query the database
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def self.generate_id(existing_ids: [])
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loop do
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short_id = self.generate_short_id
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break short_id unless existing_ids.include?(short_id)
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end
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end
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private_class_method
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# base58 to avoid literal problems with prefixed 0 (i.e. when 0x123
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# is interpreted as a hex value `0x123 == 291`), and similar looking
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# characters: 0/O, I/l
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def self.generate_short_id
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SecureRandom.base58(5)
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end
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end
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