discourse/lib/pretty_text.rb

792 lines
26 KiB
Ruby

# frozen_string_literal: true
require "mini_racer"
require "nokogiri"
require "erb"
module PrettyText
DANGEROUS_BIDI_CHARACTERS = [
"\u202A",
"\u202B",
"\u202C",
"\u202D",
"\u202E",
"\u2066",
"\u2067",
"\u2068",
"\u2069",
].freeze
DANGEROUS_BIDI_REGEXP = Regexp.new(DANGEROUS_BIDI_CHARACTERS.join("|")).freeze
BLOCKED_HOTLINKED_SRC_ATTR = "data-blocked-hotlinked-src"
BLOCKED_HOTLINKED_SRCSET_ATTR = "data-blocked-hotlinked-srcset"
@mutex = Mutex.new
@ctx_init = Mutex.new
def self.app_root
Rails.root
end
def self.apply_es6_file(ctx:, path:, module_name:)
source = File.read(path)
transpiler = DiscourseJsProcessor::Transpiler.new
transpiled = transpiler.perform(source, nil, module_name)
ctx.eval(transpiled, filename: module_name)
end
def self.ctx_load_directory(ctx:, base_path:, module_prefix:)
Dir["**/*.js", base: base_path].sort.each do |f|
module_name = "#{module_prefix}#{f.delete_suffix(".js")}"
apply_es6_file(ctx: ctx, path: File.join(base_path, f), module_name: module_name)
end
end
def self.create_es6_context
ctx = MiniRacer::Context.new(timeout: 25_000, ensure_gc_after_idle: 2000)
ctx.eval("window = globalThis; window.devicePixelRatio = 2;") # hack to make code think stuff is retina
ctx.attach("rails.logger.info", proc { |err| Rails.logger.info(err.to_s) })
ctx.attach("rails.logger.warn", proc { |err| Rails.logger.warn(err.to_s) })
ctx.attach("rails.logger.error", proc { |err| Rails.logger.error(err.to_s) })
ctx.eval <<~JS
console = {
prefix: "[PrettyText] ",
log: function(...args){ rails.logger.info(console.prefix + args.join(" ")); },
warn: function(...args){ rails.logger.warn(console.prefix + args.join(" ")); },
error: function(...args){ rails.logger.error(console.prefix + args.join(" ")); }
}
JS
ctx.eval("__PRETTY_TEXT = true")
PrettyText::Helpers.instance_methods.each do |method|
ctx.attach("__helpers.#{method}", PrettyText::Helpers.method(method))
end
root_path = "#{Rails.root}/app/assets/javascripts"
node_modules = "#{Rails.root}/node_modules"
md_node_modules = "#{Rails.root}/app/assets/javascripts/discourse-markdown-it/node_modules"
ctx.load("#{node_modules}/loader.js/dist/loader/loader.js")
ctx.load("#{md_node_modules}/markdown-it/dist/markdown-it.js")
ctx.load("#{root_path}/handlebars-shim.js")
ctx.load("#{node_modules}/xss/dist/xss.js")
ctx.load("#{Rails.root}/lib/pretty_text/vendor-shims.js")
ctx_load_directory(
ctx: ctx,
base_path: "#{root_path}/pretty-text/addon",
module_prefix: "pretty-text/",
)
ctx_load_directory(
ctx: ctx,
base_path: "#{root_path}/discourse-markdown-it/src",
module_prefix: "discourse-markdown-it/",
)
%w[
discourse-common/addon/lib/get-url
discourse-common/addon/lib/object
discourse-common/addon/lib/deprecated
discourse-common/addon/lib/escape
discourse-common/addon/lib/avatar-utils
discourse-common/addon/lib/case-converter
discourse/app/lib/to-markdown
discourse/app/static/markdown-it/features
].each do |f|
apply_es6_file(
ctx: ctx,
path: "#{root_path}/#{f}.js",
module_name: f.sub("/addon/", "/").sub("/app/", "/"),
)
end
ctx.load("#{Rails.root}/lib/pretty_text/shims.js")
ctx.eval("__setUnicode(#{Emoji.unicode_replacements_json})")
Discourse.plugins.each do |plugin|
Dir
.glob("#{plugin.directory}/assets/javascripts/**/discourse-markdown/**/*.{js,js.es6}")
.filter { |a| File.file?(a) }
.each do |f|
module_name =
f.sub(%r{\A.+assets/javascripts/}, "discourse/plugins/#{plugin.name}/").sub(
/\.js(\.es6)?\z/,
"",
)
apply_es6_file(ctx: ctx, path: f, module_name: module_name)
end
end
DiscoursePluginRegistry.vendored_core_pretty_text.each { |vpt| ctx.eval(File.read(vpt)) }
DiscoursePluginRegistry.vendored_pretty_text.each { |vpt| ctx.eval(File.read(vpt)) }
ctx
end
def self.v8
return @ctx if @ctx
# ensure we only init one of these
@ctx_init.synchronize do
return @ctx if @ctx
@ctx = create_es6_context
end
@ctx
end
def self.reset_translations
v8.eval("__resetTranslationTree()")
end
def self.reset_context
@ctx_init.synchronize do
@ctx&.dispose
@ctx = nil
end
end
# Acceptable options:
#
# disable_emojis - Disables the emoji markdown engine.
# features - A hash where the key is the markdown feature name and the value is a boolean to enable/disable the markdown feature.
# The hash is merged into the default features set in pretty-text.js which can be used to add new features or disable existing features.
# features_override - An array of markdown feature names to override the default markdown feature set. Currently used by plugins to customize what features should be enabled
# when rendering markdown.
# markdown_it_rules - An array of markdown rule names which will be applied to the markdown-it engine. Currently used by plugins to customize what markdown-it rules should be
# enabled when rendering markdown.
# topic_id - Topic id for the post being cooked.
# user_id - User id for the post being cooked.
# force_quote_link - Always create the link to the quoted topic for [quote] bbcode. Normally this only happens
# if the topic_id provided is different from the [quote topic:X].
# hashtag_context - Defaults to "topic-composer" if not supplied. Controls the order of #hashtag lookup results
# based on registered hashtag contexts from the `#register_hashtag_search_param` plugin API
# method.
def self.markdown(text, opts = {})
# we use the exact same markdown converter as the client
# TODO: use the same extensions on both client and server (in particular the template for mentions)
baked = nil
text = text || ""
protect do
context = v8
custom_emoji = {}
Emoji.custom.map { |e| custom_emoji[e.name] = e.url }
# note, any additional options added to __optInput here must be
# also be added to the buildOptions function in pretty-text.js,
# otherwise they will be discarded
buffer = +<<~JS
__optInput = {};
__optInput.siteSettings = #{SiteSetting.client_settings_json};
#{"__optInput.disableEmojis = true" if opts[:disable_emojis]}
__paths = #{paths_json};
__optInput.getURL = __getURL;
#{"__optInput.features = #{opts[:features].to_json};" if opts[:features]}
#{"__optInput.featuresOverride = #{opts[:features_override].to_json};" if opts[:features_override]}
#{"__optInput.markdownItRules = #{opts[:markdown_it_rules].to_json};" if opts[:markdown_it_rules]}
__optInput.getCurrentUser = __getCurrentUser;
__optInput.lookupAvatar = __lookupAvatar;
__optInput.lookupPrimaryUserGroup = __lookupPrimaryUserGroup;
__optInput.formatUsername = __formatUsername;
__optInput.getTopicInfo = __getTopicInfo;
__optInput.hashtagLookup = __hashtagLookup;
__optInput.customEmoji = #{custom_emoji.to_json};
__optInput.customEmojiTranslation = #{Plugin::CustomEmoji.translations.to_json};
__optInput.emojiUnicodeReplacer = __emojiUnicodeReplacer;
__optInput.emojiDenyList = #{Emoji.denied.to_json};
__optInput.lookupUploadUrls = __lookupUploadUrls;
__optInput.censoredRegexp = #{WordWatcher.serialized_regexps_for_action(:censor, engine: :js).to_json};
__optInput.watchedWordsReplace = #{WordWatcher.regexps_for_action(:replace, engine: :js).to_json};
__optInput.watchedWordsLink = #{WordWatcher.regexps_for_action(:link, engine: :js).to_json};
__optInput.additionalOptions = #{Site.markdown_additional_options.to_json};
__optInput.avatar_sizes = #{SiteSetting.avatar_sizes.to_json};
JS
buffer << "__optInput.topicId = #{opts[:topic_id].to_i};\n" if opts[:topic_id]
if opts[:force_quote_link]
buffer << "__optInput.forceQuoteLink = #{opts[:force_quote_link]};\n"
end
buffer << "__optInput.userId = #{opts[:user_id].to_i};\n" if opts[:user_id]
opts[:hashtag_context] = opts[:hashtag_context] || "topic-composer"
hashtag_types_as_js =
HashtagAutocompleteService
.ordered_types_for_context(opts[:hashtag_context])
.map { |t| "'#{t}'" }
.join(",")
buffer << "__optInput.hashtagTypesInPriorityOrder = [#{hashtag_types_as_js}];\n"
buffer << "__optInput.hashtagIcons = #{HashtagAutocompleteService.data_source_icon_map.to_json};\n"
buffer << "__pluginFeatures = __loadPluginFeatures();"
buffer << "__pt = __DiscourseMarkdownIt.withCustomFeatures(__pluginFeatures).withOptions(__optInput);"
# Be careful disabling sanitization. We allow for custom emails
buffer << ("__pt.disableSanitizer();") if opts[:sanitize] == false
opts = context.eval(buffer)
DiscourseEvent.trigger(:markdown_context, context)
baked = context.eval("__pt.cook(#{text.inspect})")
end
baked
end
def self.paths_json
paths = { baseUri: Discourse.base_path, CDN: Rails.configuration.action_controller.asset_host }
if SiteSetting.Upload.enable_s3_uploads
paths[:S3CDN] = SiteSetting.Upload.s3_cdn_url if SiteSetting.Upload.s3_cdn_url.present?
paths[:S3BaseUrl] = Discourse.store.absolute_base_url
end
paths.to_json
end
# leaving this here, cause it invokes v8, don't want to implement twice
def self.avatar_img(avatar_template, size)
protect { v8.eval(<<~JS) }
__optInput = {};
__optInput.avatar_sizes = #{SiteSetting.avatar_sizes.to_json};
__paths = #{paths_json};
require("discourse-common/lib/avatar-utils").avatarImg({size: #{size.inspect}, avatarTemplate: #{avatar_template.inspect}}, __getURL);
JS
end
def self.unescape_emoji(title)
return title unless SiteSetting.enable_emoji? && title
set = SiteSetting.emoji_set.inspect
custom = Emoji.custom.map { |e| [e.name, e.url] }.to_h.to_json
protect { v8.eval(<<~JS) }
__paths = #{paths_json};
__performEmojiUnescape(#{title.inspect}, {
getURL: __getURL,
emojiSet: #{set},
emojiCDNUrl: "#{SiteSetting.external_emoji_url.blank? ? "" : SiteSetting.external_emoji_url}",
customEmoji: #{custom},
enableEmojiShortcuts: #{SiteSetting.enable_emoji_shortcuts},
inlineEmoji: #{SiteSetting.enable_inline_emoji_translation}
});
JS
end
def self.escape_emoji(title)
return unless title
replace_emoji_shortcuts = SiteSetting.enable_emoji && SiteSetting.enable_emoji_shortcuts
protect { v8.eval(<<~JS) }
__performEmojiEscape(#{title.inspect}, {
emojiShortcuts: #{replace_emoji_shortcuts},
inlineEmoji: #{SiteSetting.enable_inline_emoji_translation}
});
JS
end
def self.cook(text, opts = {})
options = opts.dup
working_text = text.dup
sanitized = markdown(working_text, options)
doc = Nokogiri::HTML5.fragment(sanitized)
add_nofollow = !options[:omit_nofollow] && SiteSetting.add_rel_nofollow_to_user_content
add_rel_attributes_to_user_content(doc, add_nofollow)
strip_hidden_unicode_bidirectional_characters(doc)
sanitize_hotlinked_media(doc)
add_video_placeholder_image(doc)
add_mentions(doc, user_id: opts[:user_id]) if SiteSetting.enable_mentions
scrubber = Loofah::Scrubber.new { |node| node.remove if node.name == "script" }
loofah_fragment = Loofah.html5_fragment(doc.to_html)
loofah_fragment.scrub!(scrubber).to_html
end
def self.strip_hidden_unicode_bidirectional_characters(doc)
return if !DANGEROUS_BIDI_REGEXP.match?(doc.content)
doc
.css("code,pre")
.each do |code_tag|
next if !DANGEROUS_BIDI_REGEXP.match?(code_tag.content)
DANGEROUS_BIDI_CHARACTERS.each do |bidi|
next if !code_tag.content.include?(bidi)
formatted = "&lt;U+#{bidi.ord.to_s(16).upcase}&gt;"
code_tag.inner_html =
code_tag.inner_html.gsub(
bidi,
"<span class=\"bidi-warning\" title=\"#{I18n.t("post.hidden_bidi_character")}\">#{formatted}</span>",
)
end
end
end
def self.sanitize_hotlinked_media(doc)
return if !SiteSetting.block_hotlinked_media
allowed_pattern = allowed_src_pattern
doc
.css("img[src], source[src], source[srcset], track[src], div[data-video-src]")
.each do |el|
if el["src"] && !el["src"].match?(allowed_pattern)
el[PrettyText::BLOCKED_HOTLINKED_SRC_ATTR] = el.delete("src")
end
if el["data-video-src"] && !el["data-video-src"].match?(allowed_pattern)
el[PrettyText::BLOCKED_HOTLINKED_SRC_ATTR] = el["data-video-src"]
end
if el["srcset"]
srcs = el["srcset"].split(",").map { |e| e.split(" ", 2)[0].presence }
if srcs.any? { |src| !src.match?(allowed_pattern) }
el[PrettyText::BLOCKED_HOTLINKED_SRCSET_ATTR] = el.delete("srcset")
end
end
end
end
def self.add_rel_attributes_to_user_content(doc, add_nofollow)
allowlist = []
domains = SiteSetting.exclude_rel_nofollow_domains
allowlist = domains.split("|") if domains.present?
site_uri = nil
doc
.css("a")
.each do |l|
href = l["href"].to_s
l["rel"] = "noopener" if l["target"] == "_blank"
begin
uri = URI(UrlHelper.encode_component(href))
site_uri ||= URI(Discourse.base_url)
same_domain =
!uri.host.present? || uri.host == site_uri.host ||
uri.host.ends_with?(".#{site_uri.host}") ||
allowlist.any? { |u| uri.host == u || uri.host.ends_with?(".#{u}") }
l["rel"] = "noopener nofollow ugc" if add_nofollow && !same_domain
rescue URI::Error
# add a nofollow anyway
l["rel"] = "noopener nofollow ugc"
end
end
end
class DetectedLink < Struct.new(:url, :is_quote)
end
def self.extract_links(html)
links = []
doc = Nokogiri::HTML5.fragment(html)
# extract onebox links
doc
.css("aside.onebox[data-onebox-src]")
.each { |onebox| links << DetectedLink.new(onebox["data-onebox-src"], false) }
# remove href inside quotes & oneboxes & elided part
doc.css("aside.quote a, aside.onebox a, .elided a").remove
# remove hotlinked images
doc.css("a.lightbox > img, a.onebox > img").each { |img| img.parent.remove }
# extract all links
doc
.css("a")
.each do |a|
links << DetectedLink.new(a["href"], false) if a["href"].present? && a["href"][0] != "#"
end
# extract quotes
doc
.css("aside.quote[data-topic]")
.each do |aside|
if aside["data-topic"].present?
url = +"/t/#{aside["data-topic"]}"
url << "/#{aside["data-post"]}" if aside["data-post"].present?
links << DetectedLink.new(url, true)
end
end
# extract Youtube links
doc
.css("div[data-video-id]")
.each do |div|
if div["data-video-id"].present? && div["data-provider-name"].present?
base_url =
case div["data-provider-name"]
when "youtube"
"https://www.youtube.com/watch?v="
when "vimeo"
"https://vimeo.com/"
when "tiktok"
"https://m.tiktok.com/v/"
end
links << DetectedLink.new(base_url + div["data-video-id"], false)
end
end
links
end
def self.add_video_placeholder_image(doc)
doc
.css(".video-placeholder-container")
.each do |video|
video_src = video["data-video-src"]
video_sha1 = File.basename(video_src, File.extname(video_src))
thumbnail = Upload.where("original_filename LIKE ?", "#{video_sha1}.%").last
if thumbnail
video["data-thumbnail-src"] = UrlHelper.absolute(
GlobalPath.upload_cdn_path(thumbnail.url),
)
end
end
end
def self.extract_mentions(cooked)
mentions =
cooked
.css(".mention, .mention-group")
.filter_map do |e|
if (name = e.inner_text)
User.normalize_username(name[1..-1]) if name[0] == "@"
end
end
mentions =
DiscoursePluginRegistry.apply_modifier(:pretty_text_extract_mentions, mentions, cooked)
mentions.compact!
mentions.uniq!
mentions
end
def self.excerpt(html, max_length, options = {})
# TODO: properly fix this HACK in ExcerptParser without introducing XSS
doc = Nokogiri::HTML5.fragment(html)
DiscourseEvent.trigger(:reduce_excerpt, doc, options)
strip_image_wrapping(doc)
strip_oneboxed_media(doc)
convert_hashtag_links_to_plaintext(doc) if options[:plain_hashtags]
html = doc.to_html
ExcerptParser.get_excerpt(html, max_length, options)
end
def self.convert_hashtag_links_to_plaintext(doc)
doc
.css("a.hashtag-cooked")
.each { |hashtag| hashtag.replace("##{hashtag.attributes["data-slug"]}") }
end
def self.strip_links(string)
return string if string.blank?
# If the user is not basic, strip links from their bio
fragment = Nokogiri::HTML5.fragment(string)
fragment.css("a").each { |a| a.replace(a.inner_html) }
fragment.to_html
end
def self.make_all_links_absolute(doc)
doc
.css("a[href]")
.each do |a|
begin
href = a["href"].to_s
next if href.blank?
next if href.start_with?("mailto:")
next if href.start_with?(Discourse.base_url)
next if URI(href).host.present?
a["href"] = (
if href.start_with?(Discourse.base_path)
"#{Discourse.base_url_no_prefix}#{href}"
else
"#{Discourse.base_url}#{href}"
end
)
rescue URI::Error
# leave it
end
end
end
def self.strip_image_wrapping(doc)
doc.css(".lightbox-wrapper .meta").remove
end
def self.strip_oneboxed_media(doc)
doc.css("audio").remove
doc.css(".video-onebox,video").remove
end
def self.convert_vimeo_iframes(doc)
doc
.css("iframe[src*='player.vimeo.com']")
.each do |iframe|
if iframe["data-original-href"].present?
vimeo_url = UrlHelper.normalized_encode(iframe["data-original-href"])
else
vimeo_id = iframe["src"].split("/").last.sub("?h=", "/")
vimeo_url = "https://vimeo.com/#{vimeo_id}"
end
iframe.replace Nokogiri::HTML5.fragment("<p><a href='#{vimeo_url}'>#{vimeo_url}</a></p>")
end
end
def self.strip_secure_uploads(doc)
# images inside a lightbox or other link
doc
.css("a[href]")
.each do |a|
next if !Upload.secure_uploads_url?(a["href"])
non_image_media = %w[video audio].include?(a&.parent&.name)
target = non_image_media ? a.parent : a
if target.to_s.include?("stripped-secure-view-media") ||
target.to_s.include?("stripped-secure-view-upload")
next
end
next if a.css("img[src]").empty? && !non_image_media
if a.classes.include?("lightbox")
img = a.css("img[src]").first
srcset = img&.attributes&.[]("srcset")&.value
if srcset
# if available, use the first image from the srcset here
# so we get the optimized image instead of the possibly huge original
url = srcset.split(",").first
else
url = img["src"]
end
a.add_next_sibling secure_uploads_placeholder(
doc,
url,
width: img["width"],
height: img["height"],
)
a.remove
else
width = non_image_media ? nil : a.at_css("img").attr("width")
height = non_image_media ? nil : a.at_css("img").attr("height")
target.add_next_sibling secure_uploads_placeholder(
doc,
a["href"],
width: width,
height: height,
)
target.remove
end
end
# images by themselves or inside a onebox
doc
.css("img[src]")
.each do |img|
url =
if img.parent.classes.include?("aspect-image") && img.attributes["srcset"].present?
# we are using the first image from the srcset here so we get the
# optimized image instead of the original, because an optimized
# image may be used for the onebox thumbnail
srcset = img.attributes["srcset"].value
srcset.split(",").first
else
img["src"]
end
width = img["width"]
height = img["height"]
onebox_type = nil
if img.ancestors.css(".onebox-body").any?
if img.classes.include?("onebox-avatar-inline")
onebox_type = "avatar-inline"
else
onebox_type = "thumbnail"
end
end
# we always want this to be tiny and without any special styles
if img.classes.include?("site-icon")
onebox_type = nil
width = 16
height = 16
end
if Upload.secure_uploads_url?(url)
img.add_next_sibling secure_uploads_placeholder(
doc,
url,
onebox_type: onebox_type,
width: width,
height: height,
)
img.remove
end
end
end
def self.secure_uploads_placeholder(doc, url, onebox_type: false, width: nil, height: nil)
data_width = width ? "data-width=#{width}" : ""
data_height = height ? "data-height=#{height}" : ""
data_onebox_type = onebox_type ? "data-onebox-type='#{onebox_type}'" : ""
<<~HTML
<div class="secure-upload-notice" data-stripped-secure-upload="#{url}" #{data_onebox_type} #{data_width} #{data_height}>
#{I18n.t("emails.secure_uploads_placeholder")} <a class='stripped-secure-view-upload' href="#{url}">#{I18n.t("emails.view_redacted_media")}</a>.
</div>
HTML
end
def self.format_for_email(html, post = nil)
doc = Nokogiri::HTML5.fragment(html)
DiscourseEvent.trigger(:reduce_cooked, doc, post)
strip_secure_uploads(doc) if post&.should_secure_uploads?
strip_image_wrapping(doc)
convert_vimeo_iframes(doc)
make_all_links_absolute(doc)
doc.to_html
end
protected
class JavaScriptError < StandardError
attr_accessor :message, :backtrace
def initialize(message, backtrace)
@message = message
@backtrace = backtrace
end
end
def self.protect
rval = nil
@mutex.synchronize { rval = yield }
rval
end
private
USER_TYPE ||= "user"
GROUP_TYPE ||= "group"
GROUP_MENTIONABLE_TYPE ||= "group-mentionable"
def self.add_mentions(doc, user_id: nil)
elements = doc.css("span.mention")
names = elements.map { |element| element.text[1..-1] }
mentions = lookup_mentions(names, user_id: user_id)
elements.each do |element|
name = element.text[1..-1]
name.downcase!
if type = mentions[name]
element.name = "a"
element.children = PrettyText::Helpers.format_username(element.children.text)
case type
when USER_TYPE
element["href"] = "#{Discourse.base_path}/u/#{UrlHelper.encode_component(name)}"
when GROUP_MENTIONABLE_TYPE
element["class"] = "mention-group notify"
element["href"] = "#{Discourse.base_path}/groups/#{UrlHelper.encode_component(name)}"
when GROUP_TYPE
element["class"] = "mention-group"
element["href"] = "#{Discourse.base_path}/groups/#{UrlHelper.encode_component(name)}"
end
end
end
end
def self.lookup_mentions(names, user_id: nil)
return {} if names.blank?
sql = <<~SQL
(
SELECT
:user_type AS type,
username_lower AS name
FROM users
WHERE username_lower IN (:names) AND staged = false
)
UNION
(
SELECT
:group_type AS type,
lower(name) AS name
FROM groups
)
UNION
(
SELECT
:group_mentionable_type AS type,
lower(name) AS name
FROM groups
WHERE lower(name) IN (:names) AND (#{Group.mentionable_sql_clause(include_public: false)})
)
ORDER BY type
SQL
user = User.find_by(id: user_id)
names.each(&:downcase!)
results =
DB.query(
sql,
names: names,
user_type: USER_TYPE,
group_type: GROUP_TYPE,
group_mentionable_type: GROUP_MENTIONABLE_TYPE,
levels: Group.alias_levels(user),
user_id: user_id,
)
mentions = {}
results.each { |result| mentions[result.name] = result.type }
mentions
end
def self.allowed_src_pattern
allowed_src_prefixes = [
Discourse.base_path,
Discourse.base_url,
GlobalSetting.s3_cdn_url,
GlobalSetting.cdn_url,
SiteSetting.external_emoji_url.presence,
*SiteSetting.block_hotlinked_media_exceptions.split("|"),
]
patterns =
allowed_src_prefixes.compact.map do |url|
pattern = Regexp.escape(url)
# If 'https://example.com' is allowed, ensure 'https://example.com.blah.com' is not
pattern += '(?:/|\z)' if !pattern.ends_with?("\/")
pattern
end
/\A(data:|#{patterns.join("|")})/
end
end