discourse/lib/email/sender.rb

412 lines
14 KiB
Ruby

# frozen_string_literal: true
#
# A helper class to send an email. It will also handle a nil message, which it considers
# to be "do nothing". This is because some Mailers will decide not to do work for some
# reason. For example, emailing a user too frequently. A nil to address is also considered
# "do nothing"
#
# It also adds an HTML part for the plain text body
#
require 'uri'
require 'net/smtp'
SMTP_CLIENT_ERRORS = [Net::SMTPFatalError, Net::SMTPSyntaxError]
BYPASS_DISABLE_TYPES = %w(
admin_login
test_message
new_version
group_smtp
invite
download_backup_message
admin_confirmation_message
)
module Email
class Sender
def initialize(message, email_type, user = nil)
@message = message
@email_type = email_type
@user = user
end
def send
bypass_disable = BYPASS_DISABLE_TYPES.include?(@email_type.to_s)
if SiteSetting.disable_emails == "yes" && !bypass_disable
return
end
return if ActionMailer::Base::NullMail === @message
return if ActionMailer::Base::NullMail === (@message.message rescue nil)
return skip(SkippedEmailLog.reason_types[:sender_message_blank]) if @message.blank?
return skip(SkippedEmailLog.reason_types[:sender_message_to_blank]) if @message.to.blank?
if SiteSetting.disable_emails == "non-staff" && !bypass_disable
return unless find_user&.staff?
end
return skip(SkippedEmailLog.reason_types[:sender_message_to_invalid]) if to_address.end_with?(".invalid")
if @message.text_part
if @message.text_part.body.to_s.blank?
return skip(SkippedEmailLog.reason_types[:sender_text_part_body_blank])
end
else
if @message.body.to_s.blank?
return skip(SkippedEmailLog.reason_types[:sender_body_blank])
end
end
@message.charset = 'UTF-8'
opts = {}
renderer = Email::Renderer.new(@message, opts)
if @message.html_part
@message.html_part.body = renderer.html
else
@message.html_part = Mail::Part.new do
content_type 'text/html; charset=UTF-8'
body renderer.html
end
end
# Fix relative (ie upload) HTML links in markdown which do not work well in plain text emails.
# These are the links we add when a user uploads a file or image.
# Ideally we would parse general markdown into plain text, but that is almost an intractable problem.
url_prefix = Discourse.base_url
@message.parts[0].body = @message.parts[0].body.to_s.gsub(/<a class="attachment" href="(\/uploads\/default\/[^"]+)">([^<]*)<\/a>/, '[\2|attachment](' + url_prefix + '\1)')
@message.parts[0].body = @message.parts[0].body.to_s.gsub(/<img src="(\/uploads\/default\/[^"]+)"([^>]*)>/, '![](' + url_prefix + '\1)')
@message.text_part.content_type = 'text/plain; charset=UTF-8'
user_id = @user&.id
# Set up the email log
email_log = EmailLog.new(
email_type: @email_type,
to_address: to_address,
user_id: user_id
)
host = Email::Sender.host_for(Discourse.base_url)
post_id = header_value('X-Discourse-Post-Id')
topic_id = header_value('X-Discourse-Topic-Id')
reply_key = set_reply_key(post_id, user_id)
# always set a default Message ID from the host
@message.header['Message-ID'] = "<#{SecureRandom.uuid}@#{host}>"
if topic_id.present? && post_id.present?
post = Post.find_by(id: post_id, topic_id: topic_id)
# guards against deleted posts and topics
return skip(SkippedEmailLog.reason_types[:sender_post_deleted]) if post.blank?
topic = post.topic
return skip(SkippedEmailLog.reason_types[:sender_topic_deleted]) if topic.blank?
add_attachments(post)
first_post = topic.ordered_posts.first
topic_message_id = first_post.incoming_email&.message_id.present? ?
"<#{first_post.incoming_email.message_id}>" :
"<topic/#{topic_id}@#{host}>"
post_message_id = post.incoming_email&.message_id.present? ?
"<#{post.incoming_email.message_id}>" :
"<topic/#{topic_id}/#{post_id}@#{host}>"
referenced_posts = Post.includes(:incoming_email)
.joins("INNER JOIN post_replies ON post_replies.post_id = posts.id ")
.where("post_replies.reply_post_id = ?", post_id)
.order(id: :desc)
referenced_post_message_ids = referenced_posts.map do |referenced_post|
if referenced_post.incoming_email&.message_id.present?
"<#{referenced_post.incoming_email.message_id}>"
else
if referenced_post.post_number == 1
"<topic/#{topic_id}@#{host}>"
else
"<topic/#{topic_id}/#{referenced_post.id}@#{host}>"
end
end
end
# https://www.ietf.org/rfc/rfc2822.txt
if post.post_number == 1
@message.header['Message-ID'] = topic_message_id
else
@message.header['Message-ID'] = post_message_id
@message.header['In-Reply-To'] = referenced_post_message_ids[0] || topic_message_id
@message.header['References'] = [topic_message_id, referenced_post_message_ids].flatten.compact.uniq
end
# https://www.ietf.org/rfc/rfc2919.txt
if topic&.category && !topic.category.uncategorized?
list_id = "#{SiteSetting.title} | #{topic.category.name} <#{topic.category.name.downcase.tr(' ', '-')}.#{host}>"
# subcategory case
if !topic.category.parent_category_id.nil?
parent_category_name = Category.find_by(id: topic.category.parent_category_id).name
list_id = "#{SiteSetting.title} | #{parent_category_name} #{topic.category.name} <#{topic.category.name.downcase.tr(' ', '-')}.#{parent_category_name.downcase.tr(' ', '-')}.#{host}>"
end
else
list_id = "#{SiteSetting.title} <#{host}>"
end
# https://www.ietf.org/rfc/rfc3834.txt
@message.header['Precedence'] = 'list'
@message.header['List-ID'] = list_id
if topic
if SiteSetting.private_email?
@message.header['List-Archive'] = "#{Discourse.base_url}#{topic.slugless_url}"
else
@message.header['List-Archive'] = topic.url
end
end
end
if reply_key.present? && @message.header['Reply-To'] =~ /\<([^\>]+)\>/
email = Regexp.last_match[1]
@message.header['List-Post'] = "<mailto:#{email}>"
end
if Email::Sender.bounceable_reply_address?
email_log.bounce_key = SecureRandom.hex
# WARNING: RFC claims you can not set the Return Path header, this is 100% correct
# however Rails has special handling for this header and ends up using this value
# as the Envelope From address so stuff works as expected
@message.header[:return_path] = Email::Sender.bounce_address(email_log.bounce_key)
end
email_log.post_id = post_id if post_id.present?
# Remove headers we don't need anymore
@message.header['X-Discourse-Topic-Id'] = nil if topic_id.present?
@message.header['X-Discourse-Post-Id'] = nil if post_id.present?
if reply_key.present?
@message.header[Email::MessageBuilder::ALLOW_REPLY_BY_EMAIL_HEADER] = nil
end
# pass the original message_id when using mailjet/mandrill/sparkpost
case ActionMailer::Base.smtp_settings[:address]
when /\.mailjet\.com/
@message.header['X-MJ-CustomID'] = @message.message_id
when "smtp.mandrillapp.com"
merge_json_x_header('X-MC-Metadata', message_id: @message.message_id)
when "smtp.sparkpostmail.com"
merge_json_x_header('X-MSYS-API', metadata: { message_id: @message.message_id })
end
# Parse the HTML again so we can make any final changes before
# sending
style = Email::Styles.new(@message.html_part.body.to_s)
# Suppress images from short emails
if SiteSetting.strip_images_from_short_emails &&
@message.html_part.body.to_s.bytesize <= SiteSetting.short_email_length &&
@message.html_part.body =~ /<img[^>]+>/
style.strip_avatars_and_emojis
end
# Embeds any of the secure images that have been attached inline,
# removing the redaction notice.
if SiteSetting.secure_media_allow_embed_images_in_emails
style.inline_secure_images(@message.attachments)
end
@message.html_part.body = style.to_s
email_log.message_id = @message.message_id
DiscourseEvent.trigger(:before_email_send, @message, @email_type)
begin
@message.deliver_now
rescue *SMTP_CLIENT_ERRORS => e
return skip(SkippedEmailLog.reason_types[:custom], custom_reason: e.message)
end
email_log.save!
email_log
end
def find_user
return @user if @user
User.find_by_email(to_address)
end
def to_address
@to_address ||= begin
to = @message.try(:to)
to = to.first if Array === to
to.presence || "no_email_found"
end
end
def self.host_for(base_url)
host = "localhost"
if base_url.present?
begin
uri = URI.parse(base_url)
host = uri.host.downcase if uri.host.present?
rescue URI::Error
end
end
host
end
private
def add_attachments(post)
max_email_size = SiteSetting.email_total_attachment_size_limit_kb.kilobytes
return if max_email_size == 0
email_size = 0
post.uploads.each do |upload|
if FileHelper.is_supported_image?(upload.original_filename) &&
!should_attach_image?(upload)
next
end
next if email_size + upload.filesize > max_email_size
begin
path = if upload.local?
Discourse.store.path_for(upload)
else
Discourse.store.download(upload).path
end
@message.attachments[upload.original_filename] = File.read(path)
email_size += File.size(path)
rescue => e
Discourse.warn_exception(
e,
message: "Failed to attach file to email",
env: {
post_id: post.id,
upload_id: upload.id,
filename: upload.original_filename
}
)
end
end
fix_parts_after_attachments!
end
def should_attach_image?(upload)
return if !SiteSetting.secure_media_allow_embed_images_in_emails || !upload.secure?
return if upload.filesize > SiteSetting.secure_media_max_email_embed_image_size_kb.kilobytes
true
end
#
# Two behaviors in the mail gem collide:
#
# 1. Attachments are added as extra parts at the top level,
# 2. When there are both text and html parts, the content type is set
# to 'multipart/alternative'.
#
# Since attachments aren't alternative renderings, for emails that contain
# attachments and both html and text parts, some coercing is necessary.
#
# When there are alternative rendering and attachments, this method causes
# the top level to be 'multipart/mixed' and puts the html and text parts
# into a nested 'multipart/alternative' part.
#
# Due to mail gem magic, @message.text_part and @message.html_part still
# refer to the same objects.
#
def fix_parts_after_attachments!
has_attachments = @message.attachments.present?
has_alternative_renderings =
@message.html_part.present? && @message.text_part.present?
if has_attachments && has_alternative_renderings
@message.content_type = "multipart/mixed"
html_part = @message.html_part
@message.html_part = nil
text_part = @message.text_part
@message.text_part = nil
content = Mail::Part.new do
content_type "multipart/alternative"
# we have to re-specify the charset and give the part the decoded body
# here otherwise the parts will get encoded with US-ASCII which makes
# a bunch of characters not render correctly in the email
part content_type: "text/html; charset=utf-8", body: html_part.body.decoded
part content_type: "text/plain; charset=utf-8", body: text_part.body.decoded
end
@message.parts.unshift(content)
end
end
def header_value(name)
header = @message.header[name]
return nil unless header
header.value
end
def skip(reason_type, custom_reason: nil)
attributes = {
email_type: @email_type,
to_address: to_address,
user_id: @user&.id,
reason_type: reason_type
}
attributes[:custom_reason] = custom_reason if custom_reason
SkippedEmailLog.create!(attributes)
end
def merge_json_x_header(name, value)
data = JSON.parse(@message.header[name].to_s) rescue nil
data ||= {}
data.merge!(value)
# /!\ @message.header is not a standard ruby hash.
# It can have multiple values attached to the same key...
# In order to remove all the previous keys, we have to "nil" it.
# But for "nil" to work, there must already be a key...
@message.header[name] = ""
@message.header[name] = nil
@message.header[name] = data.to_json
end
def set_reply_key(post_id, user_id)
return if !user_id || !post_id || !header_value(Email::MessageBuilder::ALLOW_REPLY_BY_EMAIL_HEADER).present?
# use safe variant here cause we tend to see concurrency issue
reply_key = PostReplyKey.find_or_create_by_safe!(
post_id: post_id,
user_id: user_id
).reply_key
@message.header['Reply-To'] =
header_value('Reply-To').gsub!("%{reply_key}", reply_key)
end
def self.bounceable_reply_address?
SiteSetting.reply_by_email_address.present? && SiteSetting.reply_by_email_address["+"]
end
def self.bounce_address(bounce_key)
SiteSetting.reply_by_email_address.sub("%{reply_key}", "verp-#{bounce_key}")
end
end
end