123 lines
4.2 KiB
Ruby
123 lines
4.2 KiB
Ruby
# frozen_string_literal: true
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module Email
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##
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# Email Message-IDs are used in both our outbound and inbound email
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# flow. For the outbound flow via Email::Sender, we assign a unique
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# Message-ID for any emails sent out from the application.
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# If we are sending an email related to a post, such as through the
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# PostAlerter class, then the Message-ID will contain references to
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# the post ID. The host must also be included on the Message-IDs.
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# The format looks like this:
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#
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# discourse/post/POST_ID@HOST
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#
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# We previously had the following formats, but support for these
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# will be removed in 2023:
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#
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# topic/TOPIC_ID/POST_ID@HOST
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# topic/TOPIC_ID@HOST
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#
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# For the inbound email flow via Email::Receiver, we use Message-IDs
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# to discern which topic and post the inbound email reply should be
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# in response to. In this case, the Message-ID is extracted from the
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# References and/or In-Reply-To headers, and compared with either
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# the IncomingEmail table, the Post table, or the IncomingEmail to
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# determine where to send the reply.
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#
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# See https://datatracker.ietf.org/doc/html/rfc2822#section-3.6.4 for
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# more specific information around Message-IDs in email.
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#
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# See https://tools.ietf.org/html/rfc850#section-2.1.7 for the
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# Message-ID format specification.
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class MessageIdService
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class << self
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def generate_default
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"<#{SecureRandom.uuid}@#{host}>"
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end
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##
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# The outbound_message_id may be present because either:
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#
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# * The post was created via incoming email and Email::Receiver, and
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# references a Message-ID generated by an external email client or service.
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# * At least one email has been sent because of the post being created
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# to inform interested parties via email.
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#
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# If it is blank then we should assume Discourse was the originator
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# of the post, and generate a Message-ID to be used from now on using
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# our discourse/post/POST_ID@HOST format.
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def generate_or_use_existing(post_ids)
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post_ids = Array.wrap(post_ids)
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return [] if post_ids.empty?
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DB.exec(<<~SQL, host: host)
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UPDATE posts
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SET outbound_message_id = 'discourse/post/' || posts.id || '@' || :host
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WHERE outbound_message_id IS NULL AND posts.id IN (#{post_ids.join(",")});
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SQL
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DB.query_single(<<~SQL)
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SELECT '<' || posts.outbound_message_id || '>'
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FROM posts
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WHERE posts.id IN (#{post_ids.join(",")})
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ORDER BY posts.created_at ASC;
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SQL
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end
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##
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# Uses extracted Message-IDs from both the In-Reply-To and References
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# headers from an incoming email.
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def find_post_from_message_ids(message_ids)
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message_ids = message_ids.map { |message_id| message_id_clean(message_id) }
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post_ids =
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message_ids
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.map { |message_id| message_id[message_id_discourse_regexp, 1] }
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.compact
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.map(&:to_i)
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post_ids << Post.where(outbound_message_id: message_ids).pluck(:id)
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post_ids << EmailLog.where(message_id: message_ids).pluck(:post_id)
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post_ids << IncomingEmail.where(message_id: message_ids).pluck(:post_id)
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post_ids.flatten!
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post_ids.compact!
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post_ids.uniq!
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return if post_ids.empty?
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Post.where(id: post_ids).order(:created_at).last
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end
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def discourse_generated_message_id?(message_id)
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message_id_discourse_regexp.match?(message_id)
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end
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def message_id_discourse_regexp
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Regexp.new "discourse/post/(\\d+)@#{Regexp.escape(host)}"
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end
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def message_id_rfc_format(message_id)
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message_id.present? && !is_message_id_rfc?(message_id) ? "<#{message_id}>" : message_id
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end
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def message_id_clean(message_id)
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if message_id.present? && is_message_id_rfc?(message_id)
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message_id.gsub(/\A<|>\z/, "")
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else
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message_id
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end
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end
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def is_message_id_rfc?(message_id)
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message_id.start_with?("<") && message_id.include?("@") && message_id.end_with?(">")
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end
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def host
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Email::Sender.host_for(Discourse.base_url)
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end
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end
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end
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end
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