summaryrefslogtreecommitdiffstats
path: root/src/plugins/lua/ratelimit.lua
blob: b265ea1ca5cc887f86de2abe5a5576e4bd22235e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
--[[
Copyright (c) 2011-2017, Vsevolod Stakhov <vsevolod@highsecure.ru>
Copyright (c) 2016-2017, Andrew Lewis <nerf@judo.za.org>

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
]]--

if confighelp then
  return
end

local rspamd_logger = require "rspamd_logger"
local rspamd_util = require "rspamd_util"
local rspamd_lua_utils = require "lua_util"
local lua_redis = require "lua_redis"
local fun = require "fun"
local lua_maps = require "lua_maps"
local lua_util = require "lua_util"
local lua_verdict = require "lua_verdict"
local rspamd_hash = require "rspamd_cryptobox_hash"
local lua_selectors = require "lua_selectors"
local ts = require("tableshape").types

-- A plugin that implements ratelimits using redis

local E = {}
local N = 'ratelimit'
local redis_params
-- Senders that are considered as bounce
local settings = {
  bounce_senders = { 'postmaster', 'mailer-daemon', '', 'null', 'fetchmail-daemon', 'mdaemon' },
-- Do not check ratelimits for these recipients
  whitelisted_rcpts = { 'postmaster', 'mailer-daemon' },
  prefix = 'RL',
  ham_factor_rate = 1.01,
  spam_factor_rate = 0.99,
  ham_factor_burst = 1.02,
  spam_factor_burst = 0.98,
  max_rate_mult = 5,
  max_bucket_mult = 10,
  expire = 60 * 60 * 24 * 2, -- 2 days by default
  limits = {},
  allow_local = false,
  prefilter = true,
}

-- Checks bucket, updating it if needed
-- KEYS[1] - prefix to update, e.g. RL_<triplet>_<seconds>
-- KEYS[2] - current time in milliseconds
-- KEYS[3] - bucket leak rate (messages per millisecond)
-- KEYS[4] - bucket burst
-- KEYS[5] - expire for a bucket
-- KEYS[6] - number of recipients
-- return 1 if message should be ratelimited and 0 if not
-- Redis keys used:
--   l - last hit
--   b - current burst
--   dr - current dynamic rate multiplier (*10000)
--   db - current dynamic burst multiplier (*10000)
local bucket_check_script = [[
  local last = redis.call('HGET', KEYS[1], 'l')
  local now = tonumber(KEYS[2])
  local dynr, dynb, leaked = 0, 0, 0
  if not last then
    -- New bucket
    redis.call('HSET', KEYS[1], 'l', KEYS[2])
    redis.call('HSET', KEYS[1], 'b', '0')
    redis.call('HSET', KEYS[1], 'dr', '10000')
    redis.call('HSET', KEYS[1], 'db', '10000')
    redis.call('EXPIRE', KEYS[1], KEYS[5])
    return {0, '0', '1', '1', '0'}
  end

  last = tonumber(last)
  local burst = tonumber(redis.call('HGET', KEYS[1], 'b'))
  -- Perform leak
  if burst > 0 then
   if last < tonumber(KEYS[2]) then
    local rate = tonumber(KEYS[3])
    dynr = tonumber(redis.call('HGET', KEYS[1], 'dr')) / 10000.0
    if dynr == 0 then dynr = 0.0001 end
    rate = rate * dynr
    leaked = ((now - last) * rate)
    if leaked > burst then leaked = burst end
    burst = burst - leaked
    redis.call('HINCRBYFLOAT', KEYS[1], 'b', -(leaked))
    redis.call('HSET', KEYS[1], 'l', KEYS[2])
   end

   dynb = tonumber(redis.call('HGET', KEYS[1], 'db')) / 10000.0
   if dynb == 0 then dynb = 0.0001 end

   if burst > 0 and (burst + tonumber(KEYS[6])) > tonumber(KEYS[4]) * dynb then
     return {1, tostring(burst), tostring(dynr), tostring(dynb), tostring(leaked)}
   end
  else
   burst = 0
   redis.call('HSET', KEYS[1], 'b', '0')
  end

  return {0, tostring(burst), tostring(dynr), tostring(dynb), tostring(leaked)}
]]
local bucket_check_id


-- Updates a bucket
-- KEYS[1] - prefix to update, e.g. RL_<triplet>_<seconds>
-- KEYS[2] - current time in milliseconds
-- KEYS[3] - dynamic rate multiplier
-- KEYS[4] - dynamic burst multiplier
-- KEYS[5] - max dyn rate (min: 1/x)
-- KEYS[6] - max burst rate (min: 1/x)
-- KEYS[7] - expire for a bucket
-- KEYS[8] - number of recipients (or increase rate)
-- Redis keys used:
--   l - last hit
--   b - current burst
--   dr - current dynamic rate multiplier
--   db - current dynamic burst multiplier
local bucket_update_script = [[
  local last = redis.call('HGET', KEYS[1], 'l')
  local now = tonumber(KEYS[2])
  if not last then
    -- New bucket
    redis.call('HSET', KEYS[1], 'l', KEYS[2])
    redis.call('HSET', KEYS[1], 'b', '1')
    redis.call('HSET', KEYS[1], 'dr', '10000')
    redis.call('HSET', KEYS[1], 'db', '10000')
    redis.call('EXPIRE', KEYS[1], KEYS[7])
    return {1, 1, 1}
  end

  local dr, db = 1.0, 1.0

  if tonumber(KEYS[5]) > 1 then
    local rate_mult = tonumber(KEYS[3])
    local rate_limit = tonumber(KEYS[5])
    dr = tonumber(redis.call('HGET', KEYS[1], 'dr')) / 10000

    if rate_mult > 1.0 and dr < rate_limit then
      dr = dr * rate_mult
      if dr > 0.0001 then
        redis.call('HSET', KEYS[1], 'dr', tostring(math.floor(dr * 10000)))
      else
        redis.call('HSET', KEYS[1], 'dr', '1')
      end
    elseif rate_mult < 1.0 and dr > (1.0 / rate_limit) then
      dr = dr * rate_mult
      if dr > 0.0001 then
        redis.call('HSET', KEYS[1], 'dr', tostring(math.floor(dr * 10000)))
      else
        redis.call('HSET', KEYS[1], 'dr', '1')
      end
    end
  end

  if tonumber(KEYS[6]) > 1 then
    local rate_mult = tonumber(KEYS[4])
    local rate_limit = tonumber(KEYS[6])
    db = tonumber(redis.call('HGET', KEYS[1], 'db')) / 10000

    if rate_mult > 1.0 and db < rate_limit then
      db = db * rate_mult
      if db > 0.0001 then
        redis.call('HSET', KEYS[1], 'db', tostring(math.floor(db * 10000)))
      else
        redis.call('HSET', KEYS[1], 'db', '1')
      end
    elseif rate_mult < 1.0 and db > (1.0 / rate_limit) then
      db = db * rate_mult
      if db > 0.0001 then
        redis.call('HSET', KEYS[1], 'db', tostring(math.floor(db * 10000)))
      else
        redis.call('HSET', KEYS[1], 'db', '1')
      end
    end
  end

  local burst = tonumber(redis.call('HGET', KEYS[1], 'b'))
  if burst < 0 then burst = 0 end

  redis.call('HINCRBYFLOAT', KEYS[1], 'b', tonumber(KEYS[8]))
  redis.call('HSET', KEYS[1], 'l', KEYS[2])
  redis.call('EXPIRE', KEYS[1], KEYS[7])

  return {tostring(burst), tostring(dr), tostring(db)}
]]
local bucket_update_id

-- message_func(task, limit_type, prefix, bucket, limit_key)
local message_func = function(_, limit_type, _, _, _)
  return string.format('Ratelimit "%s" exceeded', limit_type)
end


local function load_scripts(cfg, ev_base)
  bucket_check_id = lua_redis.add_redis_script(bucket_check_script, redis_params)
  bucket_update_id = lua_redis.add_redis_script(bucket_update_script, redis_params)
end

local limit_parser
local function parse_string_limit(lim, no_error)
  local function parse_time_suffix(s)
    if s == 's' then
      return 1
    elseif s == 'm' then
      return 60
    elseif s == 'h' then
      return 3600
    elseif s == 'd' then
      return 86400
    end
  end
  local function parse_num_suffix(s)
    if s == '' then
      return 1
    elseif s == 'k' then
      return 1000
    elseif s == 'm' then
      return 1000000
    elseif s == 'g' then
      return 1000000000
    end
  end
  local lpeg = require "lpeg"

  if not limit_parser then
    local digit = lpeg.R("09")
    limit_parser = {}
    limit_parser.integer =
    (lpeg.S("+-") ^ -1) *
            (digit   ^  1)
    limit_parser.fractional =
    (lpeg.P(".")   ) *
            (digit ^ 1)
    limit_parser.number =
    (limit_parser.integer *
            (limit_parser.fractional ^ -1)) +
            (lpeg.S("+-") * limit_parser.fractional)
    limit_parser.time = lpeg.Cf(lpeg.Cc(1) *
            (limit_parser.number / tonumber) *
            ((lpeg.S("smhd") / parse_time_suffix) ^ -1),
      function (acc, val) return acc * val end)
    limit_parser.suffixed_number = lpeg.Cf(lpeg.Cc(1) *
            (limit_parser.number / tonumber) *
            ((lpeg.S("kmg") / parse_num_suffix) ^ -1),
      function (acc, val) return acc * val end)
    limit_parser.limit = lpeg.Ct(limit_parser.suffixed_number *
            (lpeg.S(" ") ^ 0) * lpeg.S("/") * (lpeg.S(" ") ^ 0) *
            limit_parser.time)
  end
  local t = lpeg.match(limit_parser.limit, lim)

  if t and t[1] and t[2] and t[2] ~= 0 then
    return t[2], t[1]
  end

  if not no_error then
    rspamd_logger.errx(rspamd_config, 'bad limit: %s', lim)
  end

  return nil
end

local function str_to_rate(str)
  local divider,divisor = parse_string_limit(str, false)

  if not divisor then
    rspamd_logger.errx(rspamd_config, 'bad rate string: %s', str)

    return nil
  end

  return divisor / divider
end

local bucket_schema = ts.shape{
  burst = ts.number + ts.string / lua_util.dehumanize_number,
  rate = ts.number + ts.string / str_to_rate,
  skip_recipients = ts.boolean:is_optional(),
  symbol = ts.string:is_optional(),
  message = ts.string:is_optional(),
  skip_soft_reject = ts.boolean:is_optional(),
}

local function parse_limit(name, data)
  if type(data) == 'table' then
    -- 2 cases here:
    --  * old limit in format [burst, rate]
    --  * vector of strings in Andrew's string format (removed from 1.8.2)
    --  * proper bucket table
    if #data == 2 and tonumber(data[1]) and tonumber(data[2]) then
      -- Old style ratelimit
      rspamd_logger.warnx(rspamd_config, 'old style ratelimit for %s', name)
      if tonumber(data[1]) > 0 and tonumber(data[2]) > 0 then
        return {
          burst = data[1],
          rate = data[2]
        }
      elseif data[1] ~= 0 then
        rspamd_logger.warnx(rspamd_config, 'invalid numbers for %s', name)
      else
        rspamd_logger.infox(rspamd_config, 'disable limit %s, burst is zero', name)
      end

      return nil
    else
      local parsed_bucket,err = bucket_schema:transform(data)

      if not parsed_bucket or err then
        rspamd_logger.errx(rspamd_config, 'cannot parse bucket for %s: %s; original value: %s',
            name, err, data)
      else
        return parsed_bucket
      end
    end
  elseif type(data) == 'string' then
    local rep_rate, burst = parse_string_limit(data)
    rspamd_logger.warnx(rspamd_config, 'old style rate bucket config detected for %s: %s',
        name, data)
    if rep_rate and burst then
      return {
        burst = burst,
        rate = burst / rep_rate -- reciprocal
      }
    end
  end

  return nil
end

--- Check whether this addr is bounce
local function check_bounce(from)
  return fun.any(function(b) return b == from end, settings.bounce_senders)
end

local keywords = {
  ['ip'] = {
    ['get_value'] = function(task)
      local ip = task:get_ip()
      if ip and ip:is_valid() then return tostring(ip) end
      return nil
    end,
  },
  ['rip'] = {
    ['get_value'] = function(task)
      local ip = task:get_ip()
      if ip and ip:is_valid() and not ip:is_local() then return tostring(ip) end
      return nil
    end,
  },
  ['from'] = {
    ['get_value'] = function(task)
      local from = task:get_from(0)
      if ((from or E)[1] or E).addr then
        return string.lower(from[1]['addr'])
      end
      return nil
    end,
  },
  ['bounce'] = {
    ['get_value'] = function(task)
      local from = task:get_from(0)
      if not ((from or E)[1] or E).user then
        return '_'
      end
      if check_bounce(from[1]['user']) then return '_' else return nil end
    end,
  },
  ['asn'] = {
    ['get_value'] = function(task)
      local asn = task:get_mempool():get_variable('asn')
      if not asn then
        return nil
      else
        return asn
      end
    end,
  },
  ['user'] = {
    ['get_value'] = function(task)
      local auser = task:get_user()
      if not auser then
        return nil
      else
        return auser
      end
    end,
  },
  ['to'] = {
    ['get_value'] = function(task)
      return task:get_principal_recipient()
    end,
  },
  ['digest'] = {
    ['get_value'] = function(task)
      return task:get_digest()
    end,
  },
  ['attachments'] = {
    ['get_value'] = function(task)
      local parts = task:get_parts() or E
      local digests = {}

      for _,p in ipairs(parts) do
        if p:get_filename() then
          table.insert(digests, p:get_digest())
        end
      end

      if #digests > 0 then
        return table.concat(digests, '')
      end

      return nil
    end,
  },
  ['files'] = {
    ['get_value'] = function(task)
      local parts = task:get_parts() or E
      local files = {}

      for _,p in ipairs(parts) do
        local fname = p:get_filename()
        if fname then
          table.insert(files, fname)
        end
      end

      if #files > 0 then
        return table.concat(files, ':')
      end

      return nil
    end,
  },
}

local function gen_rate_key(task, rtype, bucket)
  local key_t = {tostring(lua_util.round(100000.0 / bucket.burst))}
  local key_keywords = lua_util.str_split(rtype, '_')
  local have_user = false

  for _, v in ipairs(key_keywords) do
    local ret

    if keywords[v] and type(keywords[v]['get_value']) == 'function' then
      ret = keywords[v]['get_value'](task)
    end
    if not ret then return nil end
    if v == 'user' then have_user = true end
    if type(ret) ~= 'string' then ret = tostring(ret) end
    table.insert(key_t, ret)
  end

  if have_user and not task:get_user() then
    return nil
  end

  return table.concat(key_t, ":")
end

local function make_prefix(redis_key, name, bucket)
  local hash_len = 24
  if hash_len > #redis_key then hash_len = #redis_key end
  local hash = settings.prefix ..
      string.sub(rspamd_hash.create(redis_key):base32(), 1, hash_len)
  -- Fill defaults
  if not bucket.spam_factor_rate then
    bucket.spam_factor_rate = settings.spam_factor_rate
  end
  if not bucket.ham_factor_rate then
    bucket.ham_factor_rate = settings.ham_factor_rate
  end
  if not bucket.spam_factor_burst then
    bucket.spam_factor_burst = settings.spam_factor_burst
  end
  if not bucket.ham_factor_burst then
    bucket.ham_factor_burst = settings.ham_factor_burst
  end

  return {
    bucket = bucket,
    name = name,
    hash = hash
  }
end

local function limit_to_prefixes(task, k, v, prefixes)
  local n = 0
  for _,bucket in ipairs(v.buckets) do
    if v.selector then
      local selectors = lua_selectors.process_selectors(task, v.selector)
      if selectors then
        local combined = lua_selectors.combine_selectors(task, selectors, ':')
        if type(combined) == 'string' then
          prefixes[combined] = make_prefix(combined, k, bucket)
          n = n + 1
        else
          fun.each(function(p)
            prefixes[p] = make_prefix(p, k, bucket)
            n = n + 1
          end, combined)
        end
      end
    else
      local prefix = gen_rate_key(task, k, bucket)
      if prefix then
        if type(prefix) == 'string' then
          prefixes[prefix] = make_prefix(prefix, k, bucket)
          n = n + 1
        else
          fun.each(function(p)
            prefixes[p] = make_prefix(p, k, bucket)
            n = n + 1
          end, prefix)
        end
      end
    end
  end

  return n
end

local function ratelimit_cb(task)
  if not settings.allow_local and
          rspamd_lua_utils.is_rspamc_or_controller(task) then return end

  -- Get initial task data
  local ip = task:get_from_ip()
  if ip and ip:is_valid() and settings.whitelisted_ip then
    if settings.whitelisted_ip:get_key(ip) then
      -- Do not check whitelisted ip
      rspamd_logger.infox(task, 'skip ratelimit for whitelisted IP')
      return
    end
  end
  -- Parse all rcpts
  local rcpts = task:get_recipients()
  local rcpts_user = {}
  if rcpts then
    fun.each(function(r)
      fun.each(function(type) table.insert(rcpts_user, r[type]) end, {'user', 'addr'})
    end, rcpts)

    if fun.any(function(r) return settings.whitelisted_rcpts:get_key(r) end, rcpts_user) then
      rspamd_logger.infox(task, 'skip ratelimit for whitelisted recipient')
      return
    end
  end
  -- Get user (authuser)
  if settings.whitelisted_user then
    local auser = task:get_user()
    if settings.whitelisted_user:get_key(auser) then
      rspamd_logger.infox(task, 'skip ratelimit for whitelisted user')
      return
    end
  end
  -- Now create all ratelimit prefixes
  local prefixes = {}
  local nprefixes = 0

  for k,v in pairs(settings.limits) do
    nprefixes = nprefixes + limit_to_prefixes(task, k, v, prefixes)
  end

  for k, hdl in pairs(settings.custom_keywords or E) do
    local ret, redis_key, bd = pcall(hdl, task)

    if ret then
      local bucket = parse_limit(k, bd)
      if bucket then
        prefixes[redis_key] = make_prefix(redis_key, k, bucket)
      end
      nprefixes = nprefixes + 1
    else
      rspamd_logger.errx(task, 'cannot call handler for %s: %s',
          k, redis_key)
    end
  end

  local function gen_check_cb(prefix, bucket, lim_name, lim_key)
    return function(err, data)
      if err then
        rspamd_logger.errx('cannot check limit %s: %s %s', prefix, err, data)
      elseif type(data) == 'table' and data[1] then
        lua_util.debugm(N, task,
            "got reply for limit %s (%s / %s); %s burst, %s:%s dyn, %s leaked",
            prefix, bucket.burst, bucket.rate,
            data[2], data[3], data[4], data[5])

        if data[1] == 1 then
          -- set symbol only and do NOT soft reject
          if bucket.symbol then
            -- Per bucket symbol
            task:insert_result(bucket.symbol, 1.0,
                string.format('%s(%s)', lim_name, lim_key))
          else
            if settings.symbol then
              task:insert_result(settings.symbol, 1.0,
                  string.format('%s(%s)', lim_name, lim_key))
            elseif settings.info_symbol then
              task:insert_result(settings.info_symbol, 1.0,
                  string.format('%s(%s)', lim_name, lim_key))
            end
          end
          rspamd_logger.infox(task,
              'ratelimit "%s(%s)" exceeded, (%s / %s): %s (%s:%s dyn); redis key: %s',
              lim_name, prefix,
              bucket.burst, bucket.rate,
              data[2], data[3], data[4], lim_key)

          if not settings.symbol and not bucket.skip_soft_reject then
            if not bucket.message then
              task:set_pre_result('soft reject',
                  message_func(task, lim_name, prefix, bucket, lim_key), N)
            else
              task:set_pre_result('soft reject', bucket.message)
            end
          end
        end
      end
    end
  end

  -- Don't do anything if pre-result has been already set
  if task:has_pre_result() then return end

  local _,nrcpt = task:has_recipients('smtp')
  if not nrcpt or nrcpt <= 0 then
    nrcpt = 1
  end

  if nprefixes > 0 then
    -- Save prefixes to the cache to allow update
    task:cache_set('ratelimit_prefixes', prefixes)
    local now = rspamd_util.get_time()
    now = lua_util.round(now * 1000.0) -- Get milliseconds
    -- Now call check script for all defined prefixes

    for pr,value in pairs(prefixes) do
      local bucket = value.bucket
      local rate = (bucket.rate) / 1000.0 -- Leak rate in messages/ms
      local bincr = nrcpt
      if bucket.skip_recipients then bincr = 1 end

      lua_util.debugm(N, task, "check limit %s:%s -> %s (%s/%s)",
          value.name, pr, value.hash, bucket.burst, bucket.rate)
      lua_redis.exec_redis_script(bucket_check_id,
          {key = value.hash, task = task, is_write = true},
          gen_check_cb(pr, bucket, value.name, value.hash),
          {value.hash, tostring(now), tostring(rate), tostring(bucket.burst),
           tostring(settings.expire), tostring(bincr)})
    end
  end
end

local function ratelimit_update_cb(task)
  if task:has_flag('skip') then return end
  if not settings.allow_local and lua_util.is_rspamc_or_controller(task) then return end
  local prefixes = task:cache_get('ratelimit_prefixes')

  if prefixes then
    if task:has_pre_result() then
      -- Already rate limited/greylisted, do nothing
      lua_util.debugm(N, task, 'pre-action has been set, do not update')
      return
    end

    local verdict = lua_verdict.get_specific_verdict(N, task)
    local _,nrcpt = task:has_recipients('smtp')
    if not nrcpt or nrcpt <= 0 then
      nrcpt = 1
    end

    -- Update each bucket
    for k, v in pairs(prefixes) do
      local bucket = v.bucket
      local function update_bucket_cb(err, data)
        if err then
          rspamd_logger.errx(task, 'cannot update rate bucket %s: %s',
              k, err)
        else
          lua_util.debugm(N, task,
              "updated limit %s:%s -> %s (%s/%s), burst: %s, dyn_rate: %s, dyn_burst: %s",
              v.name, k, v.hash,
              bucket.burst, bucket.rate,
              data[1], data[2], data[3])
        end
      end
      local now = rspamd_util.get_time()
      now = lua_util.round(now * 1000.0) -- Get milliseconds
      local mult_burst = 1.0
      local mult_rate = 1.0

      if verdict == 'spam' or verdict == 'junk' then
        mult_burst = bucket.spam_factor_burst or 1.0
        mult_rate = bucket.spam_factor_rate or 1.0
      elseif verdict == 'ham' then
        mult_burst = bucket.ham_factor_burst or 1.0
        mult_rate = bucket.ham_factor_rate or 1.0
      end

      local bincr = nrcpt
      if bucket.skip_recipients then bincr = 1 end

      lua_redis.exec_redis_script(bucket_update_id,
          {key = v.hash, task = task, is_write = true},
          update_bucket_cb,
          {v.hash, tostring(now), tostring(mult_rate), tostring(mult_burst),
           tostring(settings.max_rate_mult), tostring(settings.max_bucket_mult),
           tostring(settings.expire), tostring(bincr)})
    end
  end
end

local opts = rspamd_config:get_all_opt(N)
if opts then

  settings = lua_util.override_defaults(settings, opts)

  if opts['limit'] then
    rspamd_logger.errx(rspamd_config, 'Legacy ratelimit config format no longer supported')
  end

  if opts['rates'] and type(opts['rates']) == 'table' then
    -- new way of setting limits
    fun.each(function(t, lim)
      local buckets = {}

      if type(lim) == 'table' and lim.bucket then

        if lim.bucket[1] then
          for _,bucket in ipairs(lim.bucket) do
            local b = parse_limit(t, bucket)

            if not b then
              rspamd_logger.errx(rspamd_config, 'bad ratelimit bucket for %s: "%s"',
                  t, b)
              return
            end

            table.insert(buckets, b)
          end
        else
          local bucket = parse_limit(t, lim.bucket)

          if not bucket then
            rspamd_logger.errx(rspamd_config, 'bad ratelimit bucket for %s: "%s"',
                t, lim.bucket)
            return
          end

          buckets = {bucket}
        end

        settings.limits[t] = {
          buckets = buckets
        }

        if lim.selector then
          local selector = lua_selectors.parse_selector(rspamd_config, lim.selector)
          if not selector then
            rspamd_logger.errx(rspamd_config, 'bad ratelimit selector for %s: "%s"',
                t, lim.selector)
            settings.limits[t] = nil
            return
          end

          settings.limits[t].selector = selector
        end
      else
        rspamd_logger.warnx(rspamd_config, 'old syntax for ratelimits: %s', lim)
        buckets = parse_limit(t, lim)
        if buckets then
          settings.limits[t] = {
            buckets = {buckets}
          }
        end
      end
    end, opts['rates'])
  end

  -- Display what's enabled
  fun.each(function(s)
    rspamd_logger.infox(rspamd_config, 'enabled ratelimit: %s', s)
  end, fun.map(function(n,d)
    return string.format('%s [%s]', n,
        table.concat(fun.totable(fun.map(function(v)
          return string.format('symbol: %s, %s msgs burst, %s msgs/sec rate',
              v.symbol, v.burst, v.rate)
        end, d.buckets)), '; ')
    )
  end, settings.limits))

  -- Ret, ret, ret: stupid legacy stuff:
  -- If we have a string with commas then load it as as static map
  -- otherwise, apply normal logic of Rspamd maps

  local wrcpts = opts['whitelisted_rcpts']
  if type(wrcpts) == 'string' then
    if string.find(wrcpts, ',') then
      settings.whitelisted_rcpts = lua_maps.rspamd_map_add_from_ucl(
        lua_util.rspamd_str_split(wrcpts, ','), 'set', 'Ratelimit whitelisted rcpts')
    else
      settings.whitelisted_rcpts = lua_maps.rspamd_map_add_from_ucl(wrcpts, 'set',
        'Ratelimit whitelisted rcpts')
    end
  elseif type(opts['whitelisted_rcpts']) == 'table' then
    settings.whitelisted_rcpts = lua_maps.rspamd_map_add_from_ucl(wrcpts, 'set',
      'Ratelimit whitelisted rcpts')
  else
    -- Stupid default...
    settings.whitelisted_rcpts = lua_maps.rspamd_map_add_from_ucl(
        settings.whitelisted_rcpts, 'set', 'Ratelimit whitelisted rcpts')
  end

  if opts['whitelisted_ip'] then
    settings.whitelisted_ip = lua_maps.rspamd_map_add('ratelimit', 'whitelisted_ip', 'radix',
      'Ratelimit whitelist ip map')
  end

  if opts['whitelisted_user'] then
    settings.whitelisted_user = lua_maps.rspamd_map_add('ratelimit', 'whitelisted_user', 'set',
      'Ratelimit whitelist user map')
  end

  settings.custom_keywords = {}
  if opts['custom_keywords'] then
    local ret, res_or_err = pcall(loadfile(opts['custom_keywords']))

    if ret then
      opts['custom_keywords'] = {}
      if type(res_or_err) == 'table' then
        for k,hdl in pairs(res_or_err) do
          settings['custom_keywords'][k] = hdl
        end
      elseif type(res_or_err) == 'function' then
        settings['custom_keywords']['custom'] = res_or_err
      end
    else
      rspamd_logger.errx(rspamd_config, 'cannot execute %s: %s',
          opts['custom_keywords'], res_or_err)
      settings['custom_keywords'] = {}
    end
  end

  if opts['message_func'] then
    message_func = assert(load(opts['message_func']))()
  end

  redis_params = lua_redis.parse_redis_server('ratelimit')

  if not redis_params then
    rspamd_logger.infox(rspamd_config, 'no servers are specified, disabling module')
    lua_util.disable_module(N, "redis")
  else
    local s = {
      type = settings.prefilter and 'prefilter' or 'callback',
      name = 'RATELIMIT_CHECK',
      priority = 7,
      callback = ratelimit_cb,
      flags = 'empty,nostat',
    }

    local id = rspamd_config:register_symbol(s)

    -- Register per bucket symbols
    -- Display what's enabled
    fun.each(function(set, lim)
      if type(lim.buckets) == 'table' then
        for _,b in ipairs(lim.buckets) do
          if b.symbol then
            rspamd_config:register_symbol{
              type = 'virtual',
              name = b.symbol,
              score = 0.0,
              parent = id
            }
          end
        end
      end
    end, settings.limits)

    if settings.info_symbol then
      rspamd_config:register_symbol{
        type = 'virtual',
        name = settings.info_symbol,
        score = 0.0,
        parent = id
      }
    end
    if settings.symbol then
      rspamd_config:register_symbol{
        type = 'virtual',
        name = settings.symbol,
        score = 0.0, -- Might be overridden if needed
        parent = id
      }
    end

    rspamd_config:register_symbol {
      type = 'idempotent',
      name = 'RATELIMIT_UPDATE',
      callback = ratelimit_update_cb,
    }
  end
end

rspamd_config:add_on_load(function(cfg, ev_base, worker)
  load_scripts(cfg, ev_base)
end)