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FEATURE: IMAP detect spammed email and delete associated Discourse topic (#11654)

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This PR adds functionality for the IMAP sync code to detect if a UID that is missing from the mail group mailbox is in the Spam/Junk folder for the mail account, and if so delete the associated Discourse topic. This is identical to what we do for emails that are moved for Trash.

If an email is missing but not in Spam or Trash, then we mark the incoming email record with imap_missing: true. This may be used in future to further filter or identify these emails, and perhaps go hunting for them in the email account in bulk.

Note: This adds some code duplication because the trash and spam email detection and handling is very similar. I intend to do more refactors/improvements to the IMAP sync code in time because there is a lot of room for improvement.
This commit is contained in:
Martin Brennan 2021-01-14 09:54:18 +10:00 committed by GitHub
parent 8f9db3812a
commit 87961534ea
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4 changed files with 143 additions and 17 deletions
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7
db/migrate/20210107005832_add_imap_missing_column_to_incoming_email.rb Normal file
View File

@ -0,0 +1,7 @@
# frozen_string_literal: true
class AddImapMissingColumnToIncomingEmail < ActiveRecord::Migration[6.0]
def change
add_column :incoming_emails, :imap_missing, :boolean, default: false, null: false
end
end

70
lib/imap/providers/generic.rb
View File

@ -10,6 +10,10 @@ module Imap
attr_accessor :trashed_emails, :trash_uid_validity
end
class SpamMailResponse
attr_accessor :spam_emails, :spam_uid_validity
end
class BasicMail
attr_accessor :uid, :message_id
@ -172,14 +176,19 @@ module Imap
end
# Look for the special Trash XLIST attribute.
# TODO: It might be more efficient to just store this against the group.
# Another table is looking more and more attractive....
def trash_mailbox
Discourse.cache.fetch("imap_trash_mailbox_#{account_digest}", expires_in: 30.minutes) do
list_mailboxes(:Trash).first
end
end
# Look for the special Junk XLIST attribute.
def spam_mailbox
Discourse.cache.fetch("imap_spam_mailbox_#{account_digest}", expires_in: 30.minutes) do
list_mailboxes(:Junk).first
end
end
# open the trash mailbox for inspection or writing. after the yield we
# close the trash and reopen the original mailbox to continue operations.
# the normal open_mailbox call can be made if more extensive trash ops
@ -196,19 +205,26 @@ module Imap
trash_uid_validity
end
# open the spam mailbox for inspection or writing. after the yield we
# close the spam and reopen the original mailbox to continue operations.
# the normal open_mailbox call can be made if more extensive spam ops
# need to be done.
def open_spam_mailbox(write: false)
open_mailbox_before_spam = @open_mailbox_name
open_mailbox_before_spam_write = @open_mailbox_write
spam_uid_validity = open_mailbox(spam_mailbox, write: write)[:uid_validity]
yield(spam_uid_validity) if block_given?
open_mailbox(open_mailbox_before_spam, write: open_mailbox_before_spam_write)
spam_uid_validity
end
def find_trashed_by_message_ids(message_ids)
trashed_emails = []
trash_uid_validity = open_trash_mailbox do
header_message_id_terms = message_ids.map do |msgid|
"HEADER Message-ID '#{Email.message_id_rfc_format(msgid)}'"
end
# OR clauses are written in Polish notation...so the query looks like this:
# OR OR HEADER Message-ID XXXX HEADER Message-ID XXXX HEADER Message-ID XXXX
or_clauses = 'OR ' * (header_message_id_terms.length - 1)
query = "#{or_clauses}#{header_message_id_terms.join(" ")}"
trashed_email_uids = imap.uid_search(query)
trashed_email_uids = find_uids_by_message_ids(message_ids)
if trashed_email_uids.any?
trashed_emails = emails(trashed_email_uids, ["UID", "ENVELOPE"]).map do |e|
BasicMail.new(message_id: Email.message_id_clean(e['ENVELOPE'].message_id), uid: e['UID'])
@ -222,6 +238,36 @@ module Imap
end
end
def find_spam_by_message_ids(message_ids)
spam_emails = []
spam_uid_validity = open_spam_mailbox do
spam_email_uids = find_uids_by_message_ids(message_ids)
if spam_email_uids.any?
spam_emails = emails(spam_email_uids, ["UID", "ENVELOPE"]).map do |e|
BasicMail.new(message_id: Email.message_id_clean(e['ENVELOPE'].message_id), uid: e['UID'])
end
end
end
SpamMailResponse.new.tap do |resp|
resp.spam_emails = spam_emails
resp.spam_uid_validity = spam_uid_validity
end
end
def find_uids_by_message_ids(message_ids)
header_message_id_terms = message_ids.map do |msgid|
"HEADER Message-ID '#{Email.message_id_rfc_format(msgid)}'"
end
# OR clauses are written in Polish notation...so the query looks like this:
# OR OR HEADER Message-ID XXXX HEADER Message-ID XXXX HEADER Message-ID XXXX
or_clauses = 'OR ' * (header_message_id_terms.length - 1)
query = "#{or_clauses}#{header_message_id_terms.join(" ")}"
imap.uid_search(query)
end
def trash(uid)
# MOVE is way easier than doing the COPY \Deleted EXPUNGE dance ourselves.
# It is supported by Gmail and Outlook.

38
lib/imap/sync.rb
View File

@ -180,15 +180,15 @@ module Imap
# This can be done because Message-ID is unique on a mail server between mailboxes,
# where the UID will have changed when moving into the Trash mailbox. We need to get
# the new UID from the trash.
potential_spam = []
response = @provider.find_trashed_by_message_ids(missing_message_ids)
existing_incoming.each do |incoming|
matching_trashed = response.trashed_emails.find { |email| email.message_id == incoming.message_id }
# if the email is not in the trash then we don't know where it is... could
# be in any mailbox on the server or could be permanently deleted. TODO
# here would be some sort of more complex detection of "where in the world
# has this UID gone?"
next if !matching_trashed
if !matching_trashed
potential_spam << incoming
next
end
# if we deleted the topic/post ourselves in discourse then the post will
# not exist, and this sync is just updating the old UIDs to the new ones
@ -202,6 +202,34 @@ module Imap
ImapSyncLog.debug("Updating incoming ID #{incoming.id} uid data FROM [UID #{incoming.imap_uid} | UIDVALIDITY #{incoming.imap_uid_validity}] TO [UID #{matching_trashed.uid} | UIDVALIDITY #{response.trash_uid_validity}] (TRASHED)", @group)
incoming.update(imap_uid_validity: response.trash_uid_validity, imap_uid: matching_trashed.uid)
end
# This can be done because Message-ID is unique on a mail server between mailboxes,
# where the UID will have changed when moving into the Trash mailbox. We need to get
# the new UID from the spam.
response = @provider.find_spam_by_message_ids(missing_message_ids)
potential_spam.each do |incoming|
matching_spam = response.spam_emails.find { |email| email.message_id == incoming.message_id }
# if the email is not in the trash or spam then we don't know where it is... could
# be in any mailbox on the server or could be permanently deleted.
if !matching_spam
ImapSyncLog.debug("Email for incoming ID #{incoming.id} (#{incoming.message_id}) could not be found in the group mailbox, trash, or spam. It could be in another mailbox or permanently deleted.", @group)
incoming.update(imap_missing: true)
next
end
# if we deleted the topic/post ourselves in discourse then the post will
# not exist, and this sync is just updating the old UIDs to the new ones
# in the spam, and we don't need to re-destroy the post
if incoming.post
ImapSyncLog.debug("Deleting post ID #{incoming.post_id}, topic id #{incoming.topic_id}; email has been moved to spam on the IMAP server.", @group)
PostDestroyer.new(Discourse.system_user, incoming.post).destroy
end
# the email has moved mailboxes, we don't want to try marking as spam again next time
ImapSyncLog.debug("Updating incoming ID #{incoming.id} uid data FROM [UID #{incoming.imap_uid} | UIDVALIDITY #{incoming.imap_uid_validity}] TO [UID #{matching_spam.uid} | UIDVALIDITY #{response.spam_uid_validity}] (SPAM)", @group)
incoming.update(imap_uid_validity: response.spam_uid_validity, imap_uid: matching_spam.uid)
end
end
def process_new_uids(new_uids, import_mode, all_old_uids_size, all_new_uids_size)

45
spec/components/imap/sync_spec.rb
View File

@ -321,6 +321,7 @@ describe Imap::Sync do
provider.stubs(:uids).with(to: 100).returns([])
provider.stubs(:uids).with(from: 101).returns([])
provider.stubs(:find_spam_by_message_ids).returns(stub(spam_emails: []))
provider.stubs(:find_trashed_by_message_ids).returns(
stub(
trashed_emails: [
@ -341,6 +342,49 @@ describe Imap::Sync do
expect(Topic.with_deleted.find(incoming_100.topic_id).deleted_at).not_to eq(nil)
end
it "detects previously synced UIDs are missing and deletes the posts if they are in the spam/junk mailbox" do
sync_handler.process
incoming_100 = IncomingEmail.find_by(imap_uid: 100)
provider.stubs(:uids).with.returns([])
provider.stubs(:uids).with(to: 100).returns([])
provider.stubs(:uids).with(from: 101).returns([])
provider.stubs(:find_trashed_by_message_ids).returns(stub(trashed_emails: []))
provider.stubs(:find_spam_by_message_ids).returns(
stub(
spam_emails: [
stub(
uid: 10,
message_id: incoming_100.message_id
)
],
spam_uid_validity: 99
)
)
sync_handler.process
incoming_100.reload
expect(incoming_100.imap_uid_validity).to eq(99)
expect(incoming_100.imap_uid).to eq(10)
expect(Post.with_deleted.find(incoming_100.post_id).deleted_at).not_to eq(nil)
expect(Topic.with_deleted.find(incoming_100.topic_id).deleted_at).not_to eq(nil)
end
it "marks the incoming email as IMAP missing if it cannot be found in spam or trash" do
sync_handler.process
incoming_100 = IncomingEmail.find_by(imap_uid: 100)
provider.stubs(:uids).with.returns([])
provider.stubs(:uids).with(to: 100).returns([])
provider.stubs(:uids).with(from: 101).returns([])
provider.stubs(:find_trashed_by_message_ids).returns(stub(trashed_emails: []))
provider.stubs(:find_spam_by_message_ids).returns(stub(spam_emails: []))
sync_handler.process
incoming_100.reload
expect(incoming_100.imap_missing).to eq(true)
end
it "detects the topic being deleted on the discourse site and deletes on the IMAP server and
does not attempt to delete again on discourse site when deleted already by us on the IMAP server" do
SiteSetting.enable_imap_write = true
@ -385,6 +429,7 @@ describe Imap::Sync do
provider.stubs(:uids).with(to: 100).returns([])
provider.stubs(:uids).with(from: 101).returns([])
provider.stubs(:find_spam_by_message_ids).returns(stub(spam_emails: []))
provider.stubs(:find_trashed_by_message_ids).returns(
stub(
trashed_emails: [