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rails--rails/actionmailbox/app/models/action_mailbox/inbound_email/message_id.rb
Pratik Naik 5cd733a334 Ensure Action Mailbox processes an email only once when received multiple times
This also adds a new column, message_checksum, to the action_mailbox_inbound_emails table
for storing SHA1 digest of the email source. Additionally, it makes generating the missing
message id deterministic and adds a unique index on message_checksum and message_id to
detect duplicate emails.
2019-01-17 11:13:40 -06:00

38 lines
1.7 KiB
Ruby

# frozen_string_literal: true
# The +Message-ID+ as specified by rfc822 is supposed to be a unique identifier for that individual email.
# That makes it an ideal tracking token for debugging and forensics, just like +X-Request-Id+ does for
# web request.
#
# If an inbound email does not, against the rfc822 mandate, specify a Message-ID, one will be generated
# using the approach from <tt>Mail::MessageIdField</tt>.
module ActionMailbox::InboundEmail::MessageId
extend ActiveSupport::Concern
class_methods do
# Create a new +InboundEmail+ from the raw +source+ of the email, which be uploaded as a Active Storage
# attachment called +raw_email+. Before the upload, extract the Message-ID from the +source+ and set
# it as an attribute on the new +InboundEmail+.
def create_and_extract_message_id!(source, **options)
message_checksum = Digest::SHA1.hexdigest(source)
message_id = extract_message_id(source) || generate_missing_message_id(message_checksum)
create! options.merge(message_id: message_id, message_checksum: message_checksum) do |inbound_email|
inbound_email.raw_email.attach io: StringIO.new(source), filename: "message.eml", content_type: "message/rfc822"
end
rescue ActiveRecord::RecordNotUnique
nil
end
private
def extract_message_id(source)
Mail.from_source(source).message_id rescue nil
end
def generate_missing_message_id(message_checksum)
Mail::MessageIdField.new("<#{message_checksum}@#{::Socket.gethostname}.mail>").message_id.tap do |message_id|
logger.warn "Message-ID couldn't be parsed or is missing. Generated a new Message-ID: #{message_id}"
end
end
end
end