134 lines
4.4 KiB
Ruby
134 lines
4.4 KiB
Ruby
# frozen_string_literal: true
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require 'uri'
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module Banzai
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module Filter
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# HTML Filter for auto-linking URLs in HTML.
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#
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# Based on HTML::Pipeline::AutolinkFilter
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#
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# Note that our CommonMark parser, `commonmarker` (using the autolink extension)
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# handles standard autolinking, like http/https. We detect additional
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# schemes (smb, rdar, etc).
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#
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# Context options:
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# :autolink - Boolean, skips all processing done by this filter when false
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# :link_attr - Hash of attributes for the generated links
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#
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class AutolinkFilter < HTML::Pipeline::Filter
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include ActionView::Helpers::TagHelper
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include Gitlab::Utils::SanitizeNodeLink
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# Pattern to match text that should be autolinked.
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#
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# A URI scheme begins with a letter and may contain letters, numbers,
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# plus, period and hyphen. Schemes are case-insensitive but we're being
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# picky here and allowing only lowercase for autolinks.
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#
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# See http://en.wikipedia.org/wiki/URI_scheme
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#
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# The negative lookbehind ensures that users can paste a URL followed by
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# punctuation without those characters being included in the generated
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# link. It matches the behaviour of Rinku 2.0.1:
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# https://github.com/vmg/rinku/blob/v2.0.1/ext/rinku/autolink.c#L65
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#
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# Rubular: http://rubular.com/r/nrL3r9yUiq
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LINK_PATTERN = %r{([a-z][a-z0-9\+\.-]+://[^\s>]+)(?<!\?|!|\.|,|:)}.freeze
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# Text matching LINK_PATTERN inside these elements will not be linked
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IGNORE_PARENTS = %w(a code kbd pre script style).to_set
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# The XPath query to use for finding text nodes to parse.
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TEXT_QUERY = %Q(descendant-or-self::text()[
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not(#{IGNORE_PARENTS.map { |p| "ancestor::#{p}" }.join(' or ')})
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and contains(., '://')
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])
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PUNCTUATION_PAIRS = {
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"'" => "'",
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'"' => '"',
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')' => '(',
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']' => '[',
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'}' => '{'
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}.freeze
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def call
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return doc if context[:autolink] == false
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doc.xpath(TEXT_QUERY).each do |node|
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content = node.to_html
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next unless content.match(LINK_PATTERN)
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html = autolink_filter(content)
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next if html == content
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node.replace(html)
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end
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doc
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end
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private
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def autolink_match(match)
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# start by stripping out dangerous links
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begin
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uri = Addressable::URI.parse(match)
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return match unless safe_protocol?(uri.scheme)
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rescue Addressable::URI::InvalidURIError
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return match
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end
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# Remove any trailing HTML entities and store them for appending
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# outside the link element. The entity must be marked HTML safe in
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# order to be output literally rather than escaped.
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match.gsub!(/((?:&[\w#]+;)+)\z/, '')
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dropped = (Regexp.last_match(1) || '').html_safe
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# To match the behaviour of Rinku, if the matched link ends with a
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# closing part of a matched pair of punctuation, we remove that trailing
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# character unless there are an equal number of closing and opening
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# characters in the link.
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if match.end_with?(*PUNCTUATION_PAIRS.keys)
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close_character = match[-1]
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close_count = match.count(close_character)
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open_character = PUNCTUATION_PAIRS[close_character]
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open_count = match.count(open_character)
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if open_count != close_count || open_character == close_character
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dropped += close_character
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match = match[0..-2]
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end
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end
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# Since this came from a Text node, make sure the new href is encoded.
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# `commonmarker` percent encodes the domains of links it handles, so
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# do the same (instead of using `normalized_encode`).
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begin
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href_safe = Addressable::URI.encode(match).html_safe
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rescue Addressable::URI::InvalidURIError
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return uri.to_s
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end
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html_safe_match = match.html_safe
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options = link_options.merge(href: href_safe)
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content_tag(:a, html_safe_match, options) + dropped
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end
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def autolink_filter(text)
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Gitlab::StringRegexMarker.new(CGI.unescapeHTML(text), text.html_safe).mark(LINK_PATTERN) do |link, left:, right:, mode:|
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autolink_match(link).html_safe
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end
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end
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def link_options
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@link_options ||= context[:link_attr] || {}
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end
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end
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end
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end
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