discourse/lib/email/styles.rb
Martin Brennan 1150cd4621
FIX: Stop secure media URLs being censored too liberally in emails (#8817)
For example /t/ URLs were being replaced if they contained secure-media-uploads so if you made a topic called "Secure Media Uploads Are Cool" the View Topic link in the user notifications would be stripped out.

Refactored code so this secure URL detection happens in one place.
2020-01-30 16:19:14 +10:00

357 lines
13 KiB
Ruby

# frozen_string_literal: true
#
# HTML emails don't support CSS, so we can use nokogiri to inline attributes based on
# matchers.
#
module Email
class Styles
@@plugin_callbacks = []
attr_accessor :fragment
delegate :css, to: :fragment
def initialize(html, opts = nil)
@html = html
@opts = opts || {}
@fragment = Nokogiri::HTML.fragment(@html)
@custom_styles = nil
end
def self.register_plugin_style(&block)
@@plugin_callbacks.push(block)
end
def add_styles(node, new_styles)
existing = node['style']
if existing.present?
# merge styles
node['style'] = "#{new_styles}; #{existing}"
else
node['style'] = new_styles
end
end
def custom_styles
return @custom_styles unless @custom_styles.nil?
css = EmailStyle.new.compiled_css
@custom_styles = {}
if !css.blank?
# there is a minor race condition here, CssParser could be
# loaded by ::CssParser::Parser not loaded
require 'css_parser' unless defined?(::CssParser::Parser)
parser = ::CssParser::Parser.new(import: false)
parser.load_string!(css)
parser.each_selector do |selector, value|
@custom_styles[selector] ||= +''
@custom_styles[selector] << value
end
end
@custom_styles
end
def format_basic
uri = URI(Discourse.base_url)
# Remove SVGs
@fragment.css('svg, img[src$=".svg"]').remove
# images
@fragment.css('img').each do |img|
next if img['class'] == 'site-logo'
if (img['class'] && img['class']['emoji']) || (img['src'] && img['src'][/\/_?emoji\//])
img['width'] = img['height'] = 20
else
# use dimensions of original iPhone screen for 'too big, let device rescale'
if img['width'].to_i > (320) || img['height'].to_i > (480)
img['width'] = img['height'] = 'auto'
end
end
if img['src']
# ensure all urls are absolute
img['src'] = "#{Discourse.base_url}#{img['src']}" if img['src'][/^\/[^\/]/]
# ensure no schemaless urls
img['src'] = "#{uri.scheme}:#{img['src']}" if img['src'][/^\/\//]
end
end
# add max-width to big images
big_images = @fragment.css('img[width="auto"][height="auto"]') -
@fragment.css('aside.onebox img') -
@fragment.css('img.site-logo, img.emoji')
big_images.each do |img|
add_styles(img, 'max-width: 100%;') if img['style'] !~ /max-width/
end
# topic featured link
@fragment.css('a.topic-featured-link').each do |e|
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);"
end
# attachments
@fragment.css('a.attachment').each do |a|
# ensure all urls are absolute
if a['href'] =~ /^\/[^\/]/
a['href'] = "#{Discourse.base_url}#{a['href']}"
end
# ensure no schemaless urls
if a['href'] && a['href'].starts_with?("//")
a['href'] = "#{uri.scheme}:#{a['href']}"
end
end
end
def onebox_styles
# Links to other topics
style('aside.quote', 'padding: 12px 25px 2px 12px; margin-bottom: 10px;')
style('aside.quote div.info-line', 'color: #666; margin: 10px 0')
style('aside.quote .avatar', 'margin-right: 5px; width:20px; height:20px; vertical-align:middle;')
style('blockquote', 'border-left: 5px solid #e9e9e9; background-color: #f8f8f8; margin: 0;')
style('blockquote > p', 'padding: 1em;')
# Oneboxes
style('aside.onebox', "border: 5px solid #e9e9e9; padding: 12px 25px 12px 12px;")
style('aside.onebox header img.site-icon', "width: 16px; height: 16px; margin-right: 3px;")
style('aside.onebox header a[href]', "color: #222222; text-decoration: none;")
style('aside.onebox .onebox-body', "clear: both")
style('aside.onebox .onebox-body img:not(.onebox-avatar-inline)', "max-height: 80%; max-width: 20%; height: auto; float: left; margin-right: 10px;")
style('aside.onebox .onebox-body img.thumbnail', "width: 60px;")
style('aside.onebox .onebox-body h3, aside.onebox .onebox-body h4', "font-size: 1.17em; margin: 10px 0;")
style('.onebox-metadata', "color: #919191")
style('.github-info', "margin-top: 10px;")
style('.github-info div', "display: inline; margin-right: 10px;")
style('.onebox-avatar-inline', "float: none; vertical-align: middle;")
@fragment.css('aside.quote blockquote > p').each do |p|
p['style'] = 'padding: 0;'
end
# Convert all `aside.quote` tags to `blockquote`s
@fragment.css('aside.quote').each do |n|
original_node = n.dup
original_node.search('div.quote-controls').remove
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>"
n.inner_html = original_node.css('div.title').inner_html + blockquote
n.name = "blockquote"
end
# Finally, convert all `aside` tags to `div`s
@fragment.css('aside, article, header').each do |n|
n.name = "div"
end
# iframes can't go in emails, so replace them with clickable links
@fragment.css('iframe').each do |i|
begin
# sometimes, iframes are blacklisted...
if i["src"].blank?
i.remove
next
end
src_uri = i["data-original-href"].present? ? URI(i["data-original-href"]) : URI(i['src'])
# If an iframe is protocol relative, use SSL when displaying it
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}"
i.replace "<p><a href='#{src_uri.to_s}'>#{CGI.escapeHTML(display_src)}</a><p>"
rescue URI::Error
# If the URL is weird, remove the iframe
i.remove
end
end
end
def format_html
correct_first_body_margin
correct_footer_style
correct_footer_style_hilight_first
reset_tables
html_lang = SiteSetting.default_locale.sub("_", "-")
style('html', nil, lang: html_lang, 'xml:lang' => html_lang)
style('body', "text-align:#{ Rtl.new(nil).enabled? ? 'right' : 'left' };")
style('body', nil, dir: Rtl.new(nil).enabled? ? 'rtl' : 'ltr')
style('.with-dir',
"text-align:#{ Rtl.new(nil).enabled? ? 'right' : 'left' };",
dir: Rtl.new(nil).enabled? ? 'rtl' : 'ltr'
)
style('.with-accent-colors', "background-color: #{SiteSetting.email_accent_bg_color}; color: #{SiteSetting.email_accent_fg_color};")
style('h4', 'color: #222;')
style('h3', 'margin: 15px 0 20px 0;')
style('hr', 'background-color: #ddd; height: 1px; border: 1px;')
style('a', "text-decoration: none; font-weight: bold; color: #{SiteSetting.email_link_color};")
style('ul', 'margin: 0 0 0 10px; padding: 0 0 0 20px;')
style('li', 'padding-bottom: 10px')
style('div.summary-footer', 'color:#666; font-size:95%; text-align:center; padding-top:15px;')
style('span.post-count', 'margin: 0 5px; color: #777;')
style('pre', 'word-wrap: break-word; max-width: 694px;')
style('code', 'background-color: #f1f1ff; padding: 2px 5px;')
style('pre code', 'display: block; background-color: #f1f1ff; padding: 5px;')
style('.featured-topic a', "text-decoration: none; font-weight: bold; color: #{SiteSetting.email_link_color}; line-height:1.5em;")
style('.secure-image-notice', 'font-style: italic; background-color: #f1f1ff; padding: 5px;')
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%")
style('.previous-discussion', 'font-size: 17px; color: #444; margin-bottom:10px;')
style('.notification-date', "text-align:right;color:#999999;padding-right:5px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;font-size:11px")
style('.username', "font-size:13px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;color:#{SiteSetting.email_link_color};text-decoration:none;font-weight:bold")
style('.user-title', "font-size:13px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;text-decoration:none;margin-left:7px;color: #999;")
style('.user-name', "font-size:13px;font-family:'lucida grande',tahoma,verdana,arial,sans-serif;text-decoration:none;margin-left:7px;color: #{SiteSetting.email_link_color};font-weight:normal;")
style('.post-wrapper', "margin-bottom:25px;")
style('.user-avatar', 'vertical-align:top;width:55px;')
style('.user-avatar img', nil, width: '45', height: '45')
style('hr', 'background-color: #ddd; height: 1px; border: 1px;')
style('.rtl', 'direction: rtl;')
style('div.body', 'padding-top:5px;')
style('.whisper div.body', 'font-style: italic; color: #9c9c9c;')
style('.lightbox-wrapper .meta', 'display: none')
style('div.undecorated-link-footer a', "font-weight: normal;")
onebox_styles
plugin_styles
style('.post-excerpt img', "max-width: 50%; max-height: 400px;")
format_custom
end
def format_custom
custom_styles.each do |selector, value|
style(selector, value)
end
end
# this method is reserved for styles specific to plugin
def plugin_styles
@@plugin_callbacks.each { |block| block.call(@fragment, @opts) }
end
def to_html
strip_classes_and_ids
replace_relative_urls
replace_secure_media_urls
@fragment.to_html
end
def strip_avatars_and_emojis
@fragment.search('img').each do |img|
next unless img['src']
if img['src'][/_avatar/]
img.parent['style'] = "vertical-align: top;" if img.parent&.name == 'td'
img.remove
end
if img['title'] && img['src'][/\/_?emoji\//]
img.add_previous_sibling(img['title'] || "emoji")
img.remove
end
end
@fragment.to_s
end
def make_all_links_absolute
site_uri = URI(Discourse.base_url)
@fragment.css("a").each do |link|
begin
link["href"] = "#{site_uri}#{link['href']}" unless URI(link["href"].to_s).host.present?
rescue URI::Error
# leave it
end
end
end
private
def replace_relative_urls
forum_uri = URI(Discourse.base_url)
host = forum_uri.host
scheme = forum_uri.scheme
@fragment.css('[href]').each do |element|
href = element['href']
if href.start_with?("\/\/#{host}")
element['href'] = "#{scheme}:#{href}"
end
end
end
def replace_secure_media_urls
@fragment.css('[href]').each do |a|
if Upload.secure_media_url?(a['href'])
a.add_next_sibling "<p class='secure-media-notice'>#{I18n.t("emails.secure_media_placeholder")}</p>"
a.remove
end
end
@fragment.search('img[src]').each do |img|
if Upload.secure_media_url?(img['src'])
img.add_next_sibling "<p class='secure-media-notice'>#{I18n.t("emails.secure_media_placeholder")}</p>"
img.remove
end
end
end
def correct_first_body_margin
@fragment.css('div.body p').each do |element|
element['style'] = "margin-top:0; border: 0;"
end
end
def correct_footer_style
@fragment.css('.footer').each do |element|
element['style'] = "color:#666;"
element.css('a').each do |inner|
inner['style'] = "color:#666;"
end
end
end
def correct_footer_style_hilight_first
footernum = 0
@fragment.css('.footer.hilight').each do |element|
linknum = 0
element.css('a').each do |inner|
# we want the first footer link to be specially highlighted as IMPORTANT
if footernum == (0) && linknum == (0)
bg_color = SiteSetting.email_accent_bg_color
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;"
end
return
end
return
end
end
def strip_classes_and_ids
@fragment.css('*').each do |element|
element.delete('class'.freeze)
element.delete('id'.freeze)
end
end
def reset_tables
style('table', nil, cellspacing: '0', cellpadding: '0', border: '0')
end
def style(selector, style, attribs = {})
@fragment.css(selector).each do |element|
add_styles(element, style) if style
attribs.each do |k, v|
element[k] = v
end
end
end
end
end