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dede942007
This PR introduces a few important changes to secure media redaction in emails. First of all, two new site settings have been introduced: * `secure_media_allow_embed_images_in_emails`: If enabled we will embed secure images in emails instead of redacting them. * `secure_media_max_email_embed_image_size_kb`: The cap to the size of the secure image we will embed, defaulting to 1mb, so the email does not become too big. Max is 10mb. Works in tandem with `email_total_attachment_size_limit_kb`. `Email::Sender` will now attach images to the email based on these settings. The sender will also call `inline_secure_images` in `Email::Styles` after secure media is redacted and attachments are added to replace redaction messages with attached images. I went with attachment and `cid` URLs because base64 image support is _still_ flaky in email clients. All redaction of secure media is now handled in `Email::Styles` and calls out to `PrettyText.strip_secure_media` to do the actual stripping and replacing with placeholders. `app/mailers/group_smtp_mailer.rb` and `app/mailers/user_notifications.rb` no longer do any stripping because they are earlier in the pipeline than `Email::Styles`. Finally the redaction notice has been restyled and includes a link to the media that the user can click, which will show it to them if they have the necessary permissions. 
392 lines
14 KiB
Ruby
392 lines
14 KiB
Ruby
# frozen_string_literal: true
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#
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# HTML emails don't support CSS, so we can use nokogiri to inline attributes based on
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# matchers.
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#
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module Email
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class Styles
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@@plugin_callbacks = []
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attr_accessor :fragment
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delegate :css, to: :fragment
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def initialize(html, opts = nil)
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@html = html
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@opts = opts || {}
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@fragment = Nokogiri::HTML5.parse(@html)
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@custom_styles = nil
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end
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def self.register_plugin_style(&block)
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@@plugin_callbacks.push(block)
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end
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def add_styles(node, new_styles)
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existing = node['style']
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if existing.present?
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# merge styles
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node['style'] = "#{new_styles}; #{existing}"
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else
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node['style'] = new_styles
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end
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end
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def custom_styles
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return @custom_styles unless @custom_styles.nil?
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css = EmailStyle.new.compiled_css
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@custom_styles = {}
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if !css.blank?
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# there is a minor race condition here, CssParser could be
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# loaded by ::CssParser::Parser not loaded
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require 'css_parser' unless defined?(::CssParser::Parser)
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parser = ::CssParser::Parser.new(import: false)
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parser.load_string!(css)
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parser.each_selector do |selector, value|
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@custom_styles[selector] ||= +''
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@custom_styles[selector] << value
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end
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end
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@custom_styles
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end
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def format_basic
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uri = URI(Discourse.base_url)
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# Remove SVGs
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@fragment.css('svg, img[src$=".svg"]').remove
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# images
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@fragment.css('img').each do |img|
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next if img['class'] == 'site-logo'
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if (img['class'] && img['class']['emoji']) || (img['src'] && img['src'][/\/_?emoji\//])
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img['width'] = img['height'] = 20
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else
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# use dimensions of original iPhone screen for 'too big, let device rescale'
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if img['width'].to_i > (320) || img['height'].to_i > (480)
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img['width'] = img['height'] = 'auto'
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end
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end
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if img['src']
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# ensure all urls are absolute
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img['src'] = "#{Discourse.base_url}#{img['src']}" if img['src'][/^\/[^\/]/]
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# ensure no schemaless urls
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img['src'] = "#{uri.scheme}:#{img['src']}" if img['src'][/^\/\//]
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end
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end
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# add max-width to big images
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big_images = @fragment.css('img[width="auto"][height="auto"]') -
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@fragment.css('aside.onebox img') -
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@fragment.css('img.site-logo, img.emoji')
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big_images.each do |img|
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add_styles(img, 'max-width: 100%;') if img['style'] !~ /max-width/
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end
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# topic featured link
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@fragment.css('a.topic-featured-link').each do |e|
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e['style'] = "color:#858585;padding:2px 8px;border:1px solid #e6e6e6;border-radius:2px;box-shadow:0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);"
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end
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# attachments
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@fragment.css('a.attachment').each do |a|
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# ensure all urls are absolute
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if a['href'] =~ /^\/[^\/]/
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a['href'] = "#{Discourse.base_url}#{a['href']}"
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end
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# ensure no schemaless urls
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if a['href'] && a['href'].starts_with?("//")
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a['href'] = "#{uri.scheme}:#{a['href']}"
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end
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end
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end
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def onebox_styles
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# Links to other topics
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style('aside.quote', 'padding: 12px 25px 2px 12px; margin-bottom: 10px;')
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style('aside.quote div.info-line', 'color: #666; margin: 10px 0')
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style('aside.quote .avatar', 'margin-right: 5px; width:20px; height:20px; vertical-align:middle;')
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style('blockquote', 'border-left: 5px solid #e9e9e9; background-color: #f8f8f8; margin: 0;')
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style('blockquote > p', 'padding: 1em;')
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# Oneboxes
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style('aside.onebox', "border: 5px solid #e9e9e9; padding: 12px 25px 12px 12px;")
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style('aside.onebox header img.site-icon', "width: 16px; height: 16px; margin-right: 3px;")
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style('aside.onebox header a[href]', "color: #222222; text-decoration: none;")
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style('aside.onebox .onebox-body', "clear: both")
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style('aside.onebox .onebox-body img:not(.onebox-avatar-inline)', "max-height: 80%; max-width: 20%; height: auto; float: left; margin-right: 10px;")
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style('aside.onebox .onebox-body img.thumbnail', "width: 60px;")
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style('aside.onebox .onebox-body h3, aside.onebox .onebox-body h4', "font-size: 1.17em; margin: 10px 0;")
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style('.onebox-metadata', "color: #919191")
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style('.github-info', "margin-top: 10px;")
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style('.github-info div', "display: inline; margin-right: 10px;")
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style('.onebox-avatar-inline', "float: none; vertical-align: middle;")
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@fragment.css('aside.quote blockquote > p').each do |p|
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p['style'] = 'padding: 0;'
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end
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# Convert all `aside.quote` tags to `blockquote`s
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@fragment.css('aside.quote').each do |n|
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original_node = n.dup
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original_node.search('div.quote-controls').remove
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blockquote = original_node.css('blockquote').inner_html.strip.start_with?("<p") ? original_node.css('blockquote').inner_html : "<p style='padding: 0;'>#{original_node.css('blockquote').inner_html}</p>"
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n.inner_html = original_node.css('div.title').inner_html + blockquote
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n.name = "blockquote"
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end
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# Finally, convert all `aside` tags to `div`s
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@fragment.css('aside, article, header').each do |n|
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n.name = "div"
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end
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# iframes can't go in emails, so replace them with clickable links
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@fragment.css('iframe').each do |i|
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begin
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# sometimes, iframes are blocklisted...
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if i["src"].blank?
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i.remove
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next
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end
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src_uri = i["data-original-href"].present? ? URI(i["data-original-href"]) : URI(i['src'])
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# If an iframe is protocol relative, use SSL when displaying it
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display_src = "#{src_uri.scheme || 'https'}://#{src_uri.host}#{src_uri.path}#{src_uri.query.nil? ? '' : '?' + src_uri.query}#{src_uri.fragment.nil? ? '' : '#' + src_uri.fragment}"
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i.replace(Nokogiri::HTML5.fragment("<p><a href='#{src_uri.to_s}'>#{CGI.escapeHTML(display_src)}</a><p>"))
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rescue URI::Error
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# If the URL is weird, remove the iframe
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i.remove
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end
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end
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end
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def format_html
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correct_first_body_margin
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correct_footer_style
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correct_footer_style_hilight_first
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reset_tables
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html_lang = SiteSetting.default_locale.sub("_", "-")
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style('html', nil, lang: html_lang, 'xml:lang' => html_lang)
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style('body', "text-align:#{ Rtl.new(nil).enabled? ? 'right' : 'left' };")
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style('body', nil, dir: Rtl.new(nil).enabled? ? 'rtl' : 'ltr')
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style('.with-dir',
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"text-align:#{ Rtl.new(nil).enabled? ? 'right' : 'left' };",
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dir: Rtl.new(nil).enabled? ? 'rtl' : 'ltr'
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)
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style('.with-accent-colors', "background-color: #{SiteSetting.email_accent_bg_color}; color: #{SiteSetting.email_accent_fg_color};")
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style('h4', 'color: #222;')
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style('h3', 'margin: 15px 0 20px 0;')
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style('hr', 'background-color: #ddd; height: 1px; border: 1px;')
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style('a', "text-decoration: none; font-weight: bold; color: #{SiteSetting.email_link_color};")
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style('ul', 'margin: 0 0 0 10px; padding: 0 0 0 20px;')
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style('li', 'padding-bottom: 10px')
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style('div.summary-footer', 'color:#666; font-size:95%; text-align:center; padding-top:15px;')
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style('span.post-count', 'margin: 0 5px; color: #777;')
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style('pre', 'word-wrap: break-word; max-width: 694px;')
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style('code', 'background-color: #f1f1ff; padding: 2px 5px;')
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style('pre code', 'display: block; background-color: #f1f1ff; padding: 5px;')
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style('.featured-topic a', "text-decoration: none; font-weight: bold; color: #{SiteSetting.email_link_color}; line-height:1.5em;")
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style('.summary-email', "-moz-box-sizing:border-box;-ms-text-size-adjust:100%;-webkit-box-sizing:border-box;-webkit-text-size-adjust:100%;box-sizing:border-box;color:#0a0a0a;font-family:Helvetica,Arial,sans-serif;font-size:14px;font-weight:400;line-height:1.3;margin:0;min-width:100%;padding:0;width:100%")
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style('.previous-discussion', 'font-size: 17px; color: #444; margin-bottom:10px;')
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style('.notification-date', "text-align:right;color:#999999;padding-right:5px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;font-size:11px")
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style('.username', "font-size:13px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;text-decoration:none;font-weight:bold")
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style('.username-link', "color:#{SiteSetting.email_link_color};")
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style('.username-title', "color:#777;margin-left:5px;")
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style('.user-title', "font-size:13px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;text-decoration:none;margin-left:5px;color: #999;")
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style('.post-wrapper', "margin-bottom:25px;")
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style('.user-avatar', 'vertical-align:top;width:55px;')
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style('.user-avatar img', nil, width: '45', height: '45')
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style('hr', 'background-color: #ddd; height: 1px; border: 1px;')
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style('.rtl', 'direction: rtl;')
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style('div.body', 'padding-top:5px;')
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style('.whisper div.body', 'font-style: italic; color: #9c9c9c;')
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style('.lightbox-wrapper .meta', 'display: none')
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style('div.undecorated-link-footer a', "font-weight: normal;")
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style('.mso-accent-link', "mso-border-alt: 6px solid #{SiteSetting.email_accent_bg_color}; background-color: #{SiteSetting.email_accent_bg_color};")
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onebox_styles
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plugin_styles
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style('.post-excerpt img', "max-width: 50%; max-height: 400px;")
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format_custom
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end
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def format_custom
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custom_styles.each do |selector, value|
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style(selector, value)
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end
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end
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# this method is reserved for styles specific to plugin
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def plugin_styles
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@@plugin_callbacks.each { |block| block.call(@fragment, @opts) }
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end
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def inline_secure_images(attachments)
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stripped_media = @fragment.css('[data-stripped-secure-media]')
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upload_shas = {}
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stripped_media.each do |div|
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url = div['data-stripped-secure-media']
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filename = File.basename(url)
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sha1 = filename.gsub(File.extname(filename), "")
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upload_shas[url] = sha1
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end
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uploads = Upload.select(:original_filename, :sha1).where(sha1: upload_shas.values)
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stripped_media.each do |div|
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upload = uploads.find { |upl| upl.sha1 == upload_shas[div['data-stripped-secure-media']] }
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next if !upload
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original_filename = upload.original_filename
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if attachments[original_filename]
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url = attachments[original_filename].url
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div.add_next_sibling(
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"<img src=\"#{url}\" data-embedded-secure-image=\"true\" style=\"max-width: 50%; max-height: 400px;\" />"
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)
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div.remove
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end
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end
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end
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def to_html
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# needs to be before class + id strip because we need to style redacted
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# media and also not double-redact already redacted from lower levels
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replace_secure_media_urls
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strip_classes_and_ids
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replace_relative_urls
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if SiteSetting.preserve_email_structure_when_styling
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@fragment.to_html
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else
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include_body? ? @fragment.at("body").to_html : @fragment.at("body").children.to_html
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end
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end
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def to_s
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@fragment.to_s
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end
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def include_body?
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@html =~ /<body>/i
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end
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def strip_avatars_and_emojis
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@fragment.search('img').each do |img|
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next unless img['src']
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if img['src'][/_avatar/]
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img.parent['style'] = "vertical-align: top;" if img.parent&.name == 'td'
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img.remove
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end
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if img['title'] && img['src'][/\/_?emoji\//]
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img.add_previous_sibling(img['title'] || "emoji")
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img.remove
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end
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end
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end
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def make_all_links_absolute
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site_uri = URI(Discourse.base_url)
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@fragment.css("a").each do |link|
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begin
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link["href"] = "#{site_uri}#{link['href']}" unless URI(link["href"].to_s).host.present?
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rescue URI::Error
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# leave it
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end
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end
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end
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private
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def replace_relative_urls
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forum_uri = URI(Discourse.base_url)
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host = forum_uri.host
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scheme = forum_uri.scheme
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@fragment.css('[href]').each do |element|
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href = element['href']
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if href.start_with?("\/\/#{host}")
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element['href'] = "#{scheme}:#{href}"
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end
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end
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end
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def replace_secure_media_urls
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# strip again, this can be done at a lower level like in the user
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# notification template but that may not catch everything
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PrettyText.strip_secure_media(@fragment)
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style('div.secure-media-notice', 'border: 5px solid #e9e9e9; padding: 5px; display: inline-block;')
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style('div.secure-media-notice a', "color: #{SiteSetting.email_link_color}")
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end
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def correct_first_body_margin
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@fragment.css('div.body p').each do |element|
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element['style'] = "margin-top:0; border: 0;"
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end
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end
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def correct_footer_style
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@fragment.css('.footer').each do |element|
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element['style'] = "color:#666;"
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element.css('a').each do |inner|
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inner['style'] = "color:#666;"
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end
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end
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end
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def correct_footer_style_hilight_first
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footernum = 0
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@fragment.css('.footer.hilight').each do |element|
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linknum = 0
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element.css('a').each do |inner|
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# we want the first footer link to be specially highlighted as IMPORTANT
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if footernum == (0) && linknum == (0)
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bg_color = SiteSetting.email_accent_bg_color
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inner['style'] = "background-color: #{bg_color}; color: #{SiteSetting.email_accent_fg_color}; border-top: 4px solid #{bg_color}; border-right: 6px solid #{bg_color}; border-bottom: 4px solid #{bg_color}; border-left: 6px solid #{bg_color}; display: inline-block; font-weight: bold;"
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end
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return
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end
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return
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end
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end
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def strip_classes_and_ids
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@fragment.css('*').each do |element|
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element.delete('class')
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element.delete('id')
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end
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end
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def reset_tables
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style('table', nil, cellspacing: '0', cellpadding: '0', border: '0')
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end
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def style(selector, style, attribs = {})
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@fragment.css(selector).each do |element|
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add_styles(element, style) if style
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attribs.each do |k, v|
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element[k] = v
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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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