67 lines
2.2 KiB
Ruby
67 lines
2.2 KiB
Ruby
# frozen_string_literal: true
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module Banzai
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module Filter
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# Sanitize HTML produced by Markdown.
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#
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# Extends Banzai::Filter::BaseSanitizationFilter with specific rules.
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class SanitizationFilter < Banzai::Filter::BaseSanitizationFilter
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# Styles used by Markdown for table alignment
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TABLE_ALIGNMENT_PATTERN = /text-align: (?<alignment>center|left|right)/.freeze
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def customize_whitelist(whitelist)
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# Allow table alignment; we whitelist specific text-align values in a
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# transformer below
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whitelist[:attributes]['th'] = %w(style)
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whitelist[:attributes]['td'] = %w(style)
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whitelist[:css] = { properties: ['text-align'] }
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# Allow the 'data-sourcepos' from CommonMark on all elements
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whitelist[:attributes][:all].push('data-sourcepos')
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# Remove any `style` properties not required for table alignment
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whitelist[:transformers].push(self.class.remove_unsafe_table_style)
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# Allow `id` in a and li elements for footnotes
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# and remove any `id` properties not matching for footnotes
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whitelist[:attributes]['a'].push('id')
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whitelist[:attributes]['li'] = %w(id)
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whitelist[:transformers].push(self.class.remove_non_footnote_ids)
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whitelist
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end
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class << self
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def remove_unsafe_table_style
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lambda do |env|
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node = env[:node]
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return unless node.name == 'th' || node.name == 'td'
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return unless node.has_attribute?('style')
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if node['style'] =~ TABLE_ALIGNMENT_PATTERN
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node['style'] = "text-align: #{$~[:alignment]}"
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else
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node.remove_attribute('style')
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end
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end
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end
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def remove_non_footnote_ids
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lambda do |env|
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node = env[:node]
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return unless node.name == 'a' || node.name == 'li'
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return unless node.has_attribute?('id')
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return if node.name == 'a' && node['id'] =~ Banzai::Filter::FootnoteFilter::FOOTNOTE_LINK_REFERENCE_PATTERN
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return if node.name == 'li' && node['id'] =~ Banzai::Filter::FootnoteFilter::FOOTNOTE_LI_REFERENCE_PATTERN
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node.remove_attribute('id')
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end
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end
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end
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end
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end
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end
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