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Contents
# Copyright (c) 2021 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true
module Contrast
module Agent
module Assess
module Policy
module Propagator
# Propagation that results in all the tags of the source being
# applied to the target. In those cases where overflow occurred,
# the overflow is tagged the same as the character which preceded it.
# The target's preexisting tags are shifted to account for this.
class Next < Contrast::Agent::Assess::Policy::Propagator::Base
class << self
# String has some silly methods like next. Basically, this flips a
# character in a predictable manner
def propagate propagation_node, preshift, target
return unless (properties = Contrast::Agent::Assess::Tracker.properties!(target))
source = find_source(propagation_node.sources[0], preshift)
properties.copy_from(source, target, 0, propagation_node.untags)
# this means the char that was shifted overflowed and created new
# chars (i.e 'z' "wraps" to create 'aa' )
unless target.length == source.length
properties.copy_from(source, target, 0, propagation_node.untags)
first_difference = (0...source.length).find { |i| source[i] != target[i] } || source.length
properties.tags_at(first_difference).each do |tag|
tag.shift_end(target.length - source.length)
end
end
properties.cleanup_tags
end
end
end
end
end
end
end
end
Version data entries
13 entries across 13 versions & 1 rubygems