discourse/lib/email/sender.rb

626 lines
23 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_password_instructions
download_backup_message
admin_confirmation_message
]
module Email
class Sender
def initialize(message, email_type, user = nil)
@message = message
@message_attachments_index = {}
@email_type = email_type
@user = user
end
def send
bypass_disable = BYPASS_DISABLE_TYPES.include?(@email_type.to_s)
return if SiteSetting.disable_emails == "yes" && !bypass_disable
return if ActionMailer::Base::NullMail === @message
if ActionMailer::Base::NullMail ===
(
begin
@message.message
rescue StandardError
nil
end
)
return
end
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
if to_address.end_with?(".invalid")
return skip(SkippedEmailLog.reason_types[:sender_message_to_invalid])
end
if @message.text_part
if @message.text_part.body.to_s.blank?
return skip(SkippedEmailLog.reason_types[:sender_text_part_body_blank])
end
else
return skip(SkippedEmailLog.reason_types[:sender_body_blank]) if @message.body.to_s.blank?
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(
%r{<a class="attachment" href="(/uploads/default/[^"]+)">([^<]*)</a>},
'[\2|attachment](' + url_prefix + '\1)',
)
@message.parts[0].body =
@message.parts[0].body.to_s.gsub(
%r{<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)
if cc_addresses.any?
email_log.cc_addresses = cc_addresses.join(";")
email_log.cc_user_ids = User.with_email(cc_addresses).pluck(:id)
end
email_log.bcc_addresses = bcc_addresses.join(";") if bcc_addresses.any?
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 = get_reply_key(post_id, user_id)
from_address = @message.from&.first
smtp_group_id =
(
if from_address.blank?
nil
else
Group.where(email_username: from_address, smtp_enabled: true).pick(:id)
end
)
# always set a default Message ID from the host
@message.header["Message-ID"] = Email::MessageIdService.generate_default
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)
add_identification_field_headers(topic, post)
# See https://www.ietf.org/rfc/rfc2919.txt for the List-ID
# specification.
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
# When we are emailing people from a group inbox, we are having a PM
# conversation with them, as a support account would. In this case
# mailing list headers do not make sense. It is not like a forum topic
# where you may have tens or hundreds of participants -- it is a
# conversation between the group and a small handful of people
# directly contacting the group, often just one person.
if !smtp_group_id
# 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
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?
email_log.topic_id = topic_id if topic_id.present?
if reply_key.present?
@message.header["Reply-To"] = header_value("Reply-To").gsub!("%{reply_key}", reply_key)
@message.header[Email::MessageBuilder::ALLOW_REPLY_BY_EMAIL_HEADER] = nil
end
MessageBuilder
.custom_headers(SiteSetting.email_custom_headers)
.each do |key, _|
# Any custom headers added via MessageBuilder that are doubled up here
# with values that we determine should be set to the last value, which is
# the one we determined. Our header values should always override the email_custom_headers.
#
# While it is valid via RFC5322 to have more than one value for certain headers,
# we just want to keep it to one, especially in cases where the custom value
# would conflict with our own.
#
# See https://datatracker.ietf.org/doc/html/rfc5322#section-3.6 and
# https://github.com/mikel/mail/blob/8ef377d6a2ca78aa5bd7f739813f5a0648482087/lib/mail/header.rb#L109-L132
custom_header = @message.header[key]
if custom_header.is_a?(Array)
our_value = custom_header.last.value
# Must be set to nil first otherwise another value is just added
# to the array of values for the header.
@message.header[key] = nil
@message.header[key] = our_value
end
value = header_value(key)
# Remove Auto-Submitted header for group private message emails, it does
# not make sense there and may hurt deliverability.
#
# From https://www.iana.org/assignments/auto-submitted-keywords/auto-submitted-keywords.xhtml:
#
# > Indicates that a message was generated by an automatic process, and is not a direct response to another message.
@message.header[key] = nil if key.downcase == "auto-submitted" && smtp_group_id
# Replace reply_key in custom headers or remove
if value&.include?("%{reply_key}")
# Delete old header first or else the same header will be added twice
@message.header[key] = nil
@message.header[key] = value.gsub!("%{reply_key}", reply_key) if reply_key.present?
end
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_uploads_allow_embed_images_in_emails
style.inline_secure_images(@message.attachments, @message_attachments_index)
end
@message.html_part.body = style.to_s
email_log.message_id = @message.message_id
# Log when a message is being sent from a group SMTP address, so we
# can debug deliverability issues.
if smtp_group_id
email_log.smtp_group_id = smtp_group_id
# Store contents of all outgoing emails using group SMTP
# for greater visibility and debugging. If the size of this
# gets out of hand, we should look into a group-level setting
# to enable this; size should be kept in check by regular purging
# of EmailLog though.
email_log.raw = Email::Cleaner.new(@message).execute
end
DiscourseEvent.trigger(:before_email_send, @message, @email_type)
begin
message_response = @message.deliver!
# TestMailer from the Mail gem does not return a real response, it
# returns an array containing @message, so we have to have this workaround.
if message_response.kind_of?(Net::SMTP::Response)
email_log.smtp_transaction_response = message_response.message&.chomp
end
rescue *SMTP_CLIENT_ERRORS => e
return skip(SkippedEmailLog.reason_types[:custom], custom_reason: e.message)
end
DiscourseEvent.trigger(:after_email_send, @message, @email_type)
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 cc_addresses
@cc_addresses ||=
begin
@message.try(:cc) || []
end
end
def bcc_addresses
@bcc_addresses ||=
begin
@message.try(:bcc) || []
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 |original_upload|
optimized_1X = original_upload.optimized_images.first
if FileHelper.is_supported_image?(original_upload.original_filename) &&
!should_attach_image?(original_upload, optimized_1X)
next
end
attached_upload = optimized_1X || original_upload
next if email_size + attached_upload.filesize > max_email_size
begin
path =
if attached_upload.local?
Discourse.store.path_for(attached_upload)
else
Discourse.store.download!(attached_upload).path
end
@message_attachments_index[original_upload.sha1] = @message.attachments.size
@message.attachments[original_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: original_upload.id,
filename: original_upload.original_filename,
},
)
end
end
fix_parts_after_attachments!
end
def should_attach_image?(upload, optimized_1X = nil)
return if !SiteSetting.secure_uploads_allow_embed_images_in_emails || !upload.secure?
if (optimized_1X&.filesize || upload.filesize) >
SiteSetting.secure_uploads_max_email_embed_image_size_kb.kilobytes
return
end
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
# NOTE: In most cases this is not a problem, but if a header has
# doubled up the header[] method will return an array. So we always
# get the last value of the array and assume that is the correct
# value.
#
# See https://github.com/mikel/mail/blob/8ef377d6a2ca78aa5bd7f739813f5a0648482087/lib/mail/header.rb#L109-L132
return header.last.value if header.is_a?(Array)
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 =
begin
JSON.parse(@message.header[name].to_s)
rescue StandardError
nil
end
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 get_reply_key(post_id, user_id)
# ALLOW_REPLY_BY_EMAIL_HEADER is only added if we are _not_ sending
# via group SMTP and if reply by email site settings are configured
if !user_id || !post_id ||
!header_value(Email::MessageBuilder::ALLOW_REPLY_BY_EMAIL_HEADER).present?
return
end
PostReplyKey.create_or_find_by!(post_id: post_id, user_id: user_id).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
##
# When sending an email for the first post (OP) of the topic, we do not
# set References or In-Reply-To headers, since there is nothing yet
# to reference. This counts as the first email in the thread.
#
# Once set, the post's `outbound_message_id` should _always_ be used
# when sending emails relating to a particular post to maintain threading.
# This will either be:
#
# a) A Message-ID generated in an external main client or service which
# is recorded when creating a post from an IncomingEmail via Email::Receiver
# b) A Message-ID generated by Discourse and recorded when sending an email
# for a newly created post, which is created and saved here to the
# outbound_message_id column on the Post.
#
# The RFC that covers using "Identification Fields", which are References,
# In-Reply-To, Message-ID, et. al. can be in the RFC link below. It's a good idea to read
# this beginning in the area immediately after these quotes, at least to understand
# the 3 main headers:
#
# > The "Message-ID:" field provides a unique message identifier that
# > refers to a particular version of a particular message. The
# > uniqueness of the message identifier is guaranteed by the host that
# > generates it.
#
# > ...
#
# > The "In-Reply-To:" field may be used to identify the message (or
# > messages) to which the new message is a reply, while the "References:"
# > field may be used to identify a "thread" of conversation.
#
# https://www.rfc-editor.org/rfc/rfc5322.html#section-3.6.4
#
# It is a long read, but to understand the decision making process for this
# threading logic you can take a look at:
#
# https://meta.discourse.org/t/discourse-email-messages-are-incorrectly-threaded/233499
def add_identification_field_headers(topic, post)
@message.header["Message-ID"] = Email::MessageIdService.generate_or_use_existing(
post.id,
).first
if post.post_number > 1
op_message_id = Email::MessageIdService.generate_or_use_existing(topic.first_post.id).first
##
# Whenever we reply to a post directly _or_ quote a post, a PostReply
# record is made, with the reply_post_id referencing the newly created
# post, and the post_id referencing the post that was quoted or replied to.
referenced_posts =
Post
.joins("INNER JOIN post_replies ON post_replies.post_id = posts.id ")
.where("post_replies.reply_post_id = ?", post.id)
.order(id: :desc)
.to_a
##
# No referenced posts means that we are just creating a new post not
# referring to anything, and as such we should just fall back to using
# the OP.
if referenced_posts.empty?
@message.header["In-Reply-To"] = op_message_id
@message.header["References"] = op_message_id
else
##
# When referencing _multiple_ posts then we just choose the most recent one
# to use for References so we have a single parent to work with, but
# every directly replied to post can go into In-Reply-To.
#
# We want to make sure all of the outbound_message_ids are already filled here.
in_reply_to_message_ids =
MessageIdService.generate_or_use_existing(referenced_posts.map(&:id))
@message.header["In-Reply-To"] = in_reply_to_message_ids
most_recent_post_message_id = in_reply_to_message_ids.last
##
# The RFC specifically states that the content of the parent's References
# field (in our case a tree of replies based on the PostReply table in
# addition to the OP post's Message-ID) first, _then_ the parent's
# Message-ID (in our case the outbound_message_id of the post we are replying to).
#
# This creates a thread from the OP all the way down to the most recent post we
# are replying to.
reply_tree = referenced_post_reply_tree(referenced_posts.first)
parent_message_ids = MessageIdService.generate_or_use_existing(reply_tree.values.flatten)
@message.header["References"] = [
op_message_id,
parent_message_ids,
most_recent_post_message_id,
].flatten.uniq
end
end
end
def referenced_post_reply_tree(post)
results = DB.query(<<~SQL, start_post_id: post.id)
WITH RECURSIVE cte AS (
SELECT reply_post_id, post_id FROM post_replies
WHERE reply_post_id = :start_post_id
UNION
SELECT pr.reply_post_id, pr.post_id
FROM post_replies pr
INNER JOIN cte
ON cte.post_id = pr.reply_post_id
)
SELECT DISTINCT cte.*, posts.created_at, posts.outbound_message_id
FROM cte
INNER JOIN posts ON posts.id = cte.reply_post_id
ORDER BY posts.created_at DESC, post_id DESC;
SQL
results.inject({}) do |hash, value|
# We only want to get a single replied-to post, which is the most recently
# created post, since we cannot deal with multiple parents for References
hash[value.reply_post_id] ||= [value.post_id]
hash
end
end
end
end