diff options
Diffstat (limited to 'app/lib/spam_check.rb')
| -rw-r--r-- | app/lib/spam_check.rb | 198 |
1 files changed, 0 insertions, 198 deletions
diff --git a/app/lib/spam_check.rb b/app/lib/spam_check.rb deleted file mode 100644 index dcb2db9ca..000000000 --- a/app/lib/spam_check.rb +++ /dev/null @@ -1,198 +0,0 @@ -# frozen_string_literal: true - -class SpamCheck - include Redisable - include ActionView::Helpers::TextHelper - - # Threshold over which two Nilsimsa values are considered - # to refer to the same text - NILSIMSA_COMPARE_THRESHOLD = 95 - - # Nilsimsa doesn't work well on small inputs, so below - # this size, we check only for exact matches with MD5 - NILSIMSA_MIN_SIZE = 10 - - # How long to keep the trail of digests between updates, - # there is no reason to store it forever - EXPIRE_SET_AFTER = 1.week.seconds - - # How many digests to keep in an account's trail. If it's - # too small, spam could rotate around different message templates - MAX_TRAIL_SIZE = 10 - - # How many detected duplicates to allow through before - # considering the message as spam - THRESHOLD = 5 - - def initialize(status) - @account = status.account - @status = status - end - - def skip? - disabled? || already_flagged? || trusted? || no_unsolicited_mentions? || solicited_reply? - end - - def spam? - if insufficient_data? - false - elsif nilsimsa? - digests_over_threshold?('nilsimsa') { |_, other_digest| nilsimsa_compare_value(digest, other_digest) >= NILSIMSA_COMPARE_THRESHOLD } - else - digests_over_threshold?('md5') { |_, other_digest| other_digest == digest } - end - end - - def flag! - auto_report_status! - end - - def remember! - # The scores in sorted sets don't actually have enough bits to hold an exact - # value of our snowflake IDs, so we use it only for its ordering property. To - # get the correct status ID back, we have to save it in the string value - - redis.zadd(redis_key, @status.id, digest_with_algorithm) - redis.zremrangebyrank(redis_key, 0, -(MAX_TRAIL_SIZE + 1)) - redis.expire(redis_key, EXPIRE_SET_AFTER) - end - - def reset! - redis.del(redis_key) - end - - def hashable_text - return @hashable_text if defined?(@hashable_text) - - @hashable_text = @status.text - @hashable_text = remove_mentions(@hashable_text) - @hashable_text = strip_tags(@hashable_text) unless @status.local? - @hashable_text = normalize_unicode(@status.spoiler_text + ' ' + @hashable_text) - @hashable_text = remove_whitespace(@hashable_text) - end - - def insufficient_data? - hashable_text.blank? - end - - def digest - @digest ||= begin - if nilsimsa? - Nilsimsa.new(hashable_text).hexdigest - else - Digest::MD5.hexdigest(hashable_text) - end - end - end - - def digest_with_algorithm - if nilsimsa? - ['nilsimsa', digest, @status.id].join(':') - else - ['md5', digest, @status.id].join(':') - end - end - - class << self - def perform(status) - spam_check = new(status) - - return if spam_check.skip? - - if spam_check.spam? - spam_check.flag! - else - spam_check.remember! - end - end - end - - private - - def disabled? - !Setting.spam_check_enabled - end - - def remove_mentions(text) - return text.gsub(Account::MENTION_RE, '') if @status.local? - - Nokogiri::HTML.fragment(text).tap do |html| - mentions = @status.mentions.map { |mention| ActivityPub::TagManager.instance.url_for(mention.account) } - - html.traverse do |element| - element.unlink if element.name == 'a' && mentions.include?(element['href']) - end - end.to_s - end - - def normalize_unicode(text) - text.unicode_normalize(:nfkc).downcase - end - - def remove_whitespace(text) - text.gsub(/\s+/, ' ').strip - end - - def auto_report_status! - status_ids = Status.where(visibility: %i(public unlisted)).where(id: matching_status_ids).pluck(:id) + [@status.id] if @status.distributable? - ReportService.new.call(Account.representative, @account, status_ids: status_ids, comment: I18n.t('spam_check.spam_detected')) - end - - def already_flagged? - @account.silenced? || @account.targeted_reports.unresolved.where(account_id: -99).exists? - end - - def trusted? - @account.trust_level > Account::TRUST_LEVELS[:untrusted] || (@account.local? && @account.user_staff?) - end - - def no_unsolicited_mentions? - @status.mentions.all? { |mention| mention.silent? || (!@account.local? && !mention.account.local?) || mention.account.following?(@account) } - end - - def solicited_reply? - !@status.thread.nil? && @status.thread.mentions.where(account: @account).exists? - end - - def nilsimsa_compare_value(first, second) - first = [first].pack('H*') - second = [second].pack('H*') - bits = 0 - - 0.upto(31) do |i| - bits += Nilsimsa::POPC[255 & (first[i].ord ^ second[i].ord)].ord - end - - 128 - bits # -128 <= Nilsimsa Compare Value <= 128 - end - - def nilsimsa? - hashable_text.size > NILSIMSA_MIN_SIZE - end - - def other_digests - redis.zrange(redis_key, 0, -1) - end - - def digests_over_threshold?(filter_algorithm) - other_digests.select do |record| - algorithm, other_digest, status_id = record.split(':') - - next unless algorithm == filter_algorithm - - yield algorithm, other_digest, status_id - end.size >= THRESHOLD - end - - def matching_status_ids - if nilsimsa? - other_digests.filter_map { |record| record.split(':')[2] if record.start_with?('nilsimsa') && nilsimsa_compare_value(digest, record.split(':')[1]) >= NILSIMSA_COMPARE_THRESHOLD } - else - other_digests.filter_map { |record| record.split(':')[2] if record.start_with?('md5') && record.split(':')[1] == digest } - end - end - - def redis_key - @redis_key ||= "spam_check:#{@account.id}" - end -end |