From 9cde61088dbbb7782294296b9a6f86ead00e4eed Mon Sep 17 00:00:00 2001
From: Andrew Lewis <nerf@judo.za.org>
Date: Sat, 26 Aug 2017 12:11:37 +0200
Subject: [PATCH] [Rework] Ratelimit module

 - Drop support for legacy options
 - Ensure incremental updates to counters
 - Support multiple limits per bucket
 - IP score: now resizes limits only (not periods)
---
 src/plugins/lua/ratelimit.lua | 586 +++++++++++++++-------------------
 1 file changed, 257 insertions(+), 329 deletions(-)

diff --git a/src/plugins/lua/ratelimit.lua b/src/plugins/lua/ratelimit.lua
index 70429cc19..3036657f0 100644
--- a/src/plugins/lua/ratelimit.lua
+++ b/src/plugins/lua/ratelimit.lua
@@ -1,5 +1,6 @@
 --[[
-Copyright (c) 2011-2015, Vsevolod Stakhov <vsevolod@highsecure.ru>
+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.
@@ -18,13 +19,10 @@ if confighelp then
   return
 end
 
--- A plugin that implements ratelimits using redis or kvstorage server
+-- A plugin that implements ratelimits using redis
 
-local E = {}
-
--- Default settings for limits, 1-st member is burst, second is rate and the third is numeric type
-local settings = {
-}
+local E, settings = {}, {}
+local N = 'ratelimit'
 -- Senders that are considered as bounce
 local bounce_senders = {'postmaster', 'mailer-daemon', '', 'null', 'fetchmail-daemon', 'mdaemon'}
 -- Do not check ratelimits for these recipients
@@ -35,9 +33,8 @@ local max_rcpt = 5
 local redis_params
 local ratelimit_symbol
 -- Do not delay mail after 1 day
-local max_delay = 24 * 3600
 local use_ip_score = false
-local rl_prefix = 'rl'
+local rl_prefix = 'RL'
 local ip_score_lower_bound = 10
 local ip_score_ham_multiplier = 1.1
 local ip_score_spam_divisor = 1.1
@@ -49,10 +46,141 @@ 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 user_keywords = {'user'}
 
+local redis_script_sha
+local redis_script = [[local bucket
+local limited = false
+local buckets = {}
+local queue_id = table.remove(ARGV)
+local now = table.remove(ARGV)
+
+local argi = 0
+for i = 1, #KEYS do
+  local key = KEYS[i]
+  local period = tonumber(ARGV[argi+1])
+  local limit = tonumber(ARGV[argi+2])
+  if not buckets[key] then
+    buckets[key] = {
+      max_period = period,
+      limits = { {period, limit} },
+    }
+  else
+    table.insert(buckets[key].limits, {period, limit})
+    if period > buckets[key].max_period then
+      buckets[key].max_period = period
+    end
+  end
+  argi = argi + 2
+end
+
+for k, v in pairs(buckets) do
+  local maxp = v.max_period
+  redis.call('ZREMRANGEBYSCORE', k, '-inf', now - maxp)
+  for _, lim in ipairs(v.limits) do
+    local period = lim[1]
+    local limit = lim[2]
+    local rate
+    if period == maxp then
+      rate = redis.call('ZCARD', k)
+    else
+      rate = redis.call('ZCOUNT', k, now - period, '+inf')
+    end
+    if rate and rate >= limit then
+      limited = true
+      bucket = k
+    end
+  end
+  redis.call('EXPIRE', k, maxp)
+  if limited then break end
+end
+
+if not limited then
+  for k in pairs(buckets) do
+    redis.call('ZADD', k, now, queue_id)
+  end
+end
+
+return {limited, bucket}]]
+
+local redis_script_symbol = [[local limited = false
+local buckets, results = {}, {}
+local queue_id = table.remove(ARGV)
+local now = table.remove(ARGV)
+
+local argi = 0
+for i = 1, #KEYS do
+  local key = KEYS[i]
+  local period = tonumber(ARGV[argi+1])
+  local limit = tonumber(ARGV[argi+2])
+  if not buckets[key] then
+    buckets[key] = {
+      max_period = period,
+      limits = { {period, limit} },
+    }
+  else
+    table.insert(buckets[key].limits, {period, limit})
+    if period > buckets[key].max_period then
+      buckets[key].max_period = period
+    end
+  end
+  argi = argi + 2
+end
+
+for k, v in pairs(buckets) do
+  local maxp = v.max_period
+  redis.call('ZREMRANGEBYSCORE', k, '-inf', now - maxp)
+  for _, lim in ipairs(v.limits) do
+    local period = lim[1]
+    local limit = lim[2]
+    local rate
+    if period == maxp then
+      rate = redis.call('ZCARD', k)
+    else
+      rate = redis.call('ZCOUNT', k, now - period, '+inf')
+    end
+    if rate then
+      local mult = 2 * math.tanh(rate / (limit * 2))
+      if mult >= 0.5 then
+        table.insert(results, {k, tostring(mult)})
+      end
+    end
+  end
+  redis.call('ZADD', k, now, queue_id)
+  redis.call('EXPIRE', k, maxp)
+end
+
+return results]]
+
+local function load_scripts(cfg, ev_base)
+  local function rl_script_cb(err, data)
+    if err then
+      rspamd_logger.errx(cfg, 'Script loading failed: ' .. err)
+    elseif type(data) == 'string' then
+      redis_script_sha = data
+    end
+  end
+  local script
+  if ratelimit_symbol then
+    script = redis_script_symbol
+  else
+    script = redis_script
+  end
+  lua_redis.redis_make_request_taskless(
+    ev_base,
+    cfg,
+    redis_params,
+    nil, -- key
+    true, -- is write
+    rl_script_cb, --callback
+    'SCRIPT', -- command
+    {'LOAD', script}
+  )
+end
+
 local limit_parser
 local function parse_string_limit(lim)
   local function parse_time_suffix(s)
@@ -107,7 +235,7 @@ local function parse_string_limit(lim)
   local t = lpeg.match(limit_parser.limit, lim)
 
   if t and t[1] and t[2] and t[2] ~= 0 then
-    return t[1] / t[2], t[1]
+    return t[2], t[1]
   end
 
   rspamd_logger.errx(rspamd_config, 'bad limit: %s', lim)
@@ -115,38 +243,6 @@ local function parse_string_limit(lim)
   return nil
 end
 
---- Parse atime and bucket of limit
-local function parse_limits(data)
-  local function parse_limit_elt(str)
-    local elts = rspamd_str_split(str, ':')
-    if not elts or #elts < 2 then
-      return {0, 0, 0}
-    else
-      local atime = tonumber(elts[1])
-      local bucket = tonumber(elts[2])
-      local ctime = atime
-
-      if elts[3] then
-        ctime = tonumber(elts[3])
-      end
-
-      if not ctime then
-        ctime = atime
-      end
-
-      return {atime,bucket,ctime}
-    end
-  end
-
-  return fun.iter(data):map(function(e)
-    if type(e) == 'string' then
-      return parse_limit_elt(e)
-    else
-      return {0, 0, 0}
-    end
-  end):totable()
-end
-
 local function resize_element(x_score, x_total, element)
   local x_ip_score
   if not x_total then x_total = 0 end
@@ -279,194 +375,7 @@ local function dynamic_rate_key(task, rtype)
   end
 end
 
---- Check specific limit inside redis
-local function check_limits(task, args)
-
-  local key = fun.foldl(function(acc, k) return acc .. k[2] end, '', args)
-  local ret
-  --- Called when value is got from server
-  local function rate_get_cb(err, data)
-    if err then
-      rspamd_logger.infox(task, 'got error while getting limit: %1', err)
-    end
-    if not data then return end
-    local ntime = rspamd_util.get_time()
-    local asn_score,total_asn,
-      country_score,total_country,
-      ipnet_score,total_ipnet,
-      ip_score, total_ip
-    if use_ip_score then
-      asn_score,total_asn,
-        country_score,total_country,
-        ipnet_score,total_ipnet,
-        ip_score, total_ip = task:get_mempool():get_variable('ip_score',
-        'double,double,double,double,double,double,double,double')
-    end
-
-    fun.each(function(elt, limit, rtype)
-      local bucket = elt[2]
-      local rate = limit[2]
-      local threshold = limit[1]
-      local atime = elt[1]
-      local ctime = elt[3]
-
-      if atime == 0 then return end
-
-      if use_ip_score then
-        local key_keywords = rspamd_str_split(rtype, '_')
-        local has_asn, has_ip = false, false
-        for _, v in ipairs(key_keywords) do
-          if v == "asn" then has_asn = true end
-          if v == "ip" then has_ip = true end
-          if has_ip and has_asn then break end
-        end
-        if has_asn and not has_ip then
-          bucket = resize_element(asn_score, total_asn, bucket)
-          rate = resize_element(asn_score, total_asn, rate)
-        elseif has_ip then
-          if total_ip and total_ip > ip_score_lower_bound then
-            bucket = resize_element(ip_score, total_ip, bucket)
-            rate = resize_element(ip_score, total_ip, rate)
-          elseif total_ipnet and total_ipnet > ip_score_lower_bound then
-            bucket = resize_element(ipnet_score, total_ipnet, bucket)
-            rate = resize_element(ipnet_score, total_ipnet, rate)
-          elseif total_asn and total_asn > ip_score_lower_bound then
-            bucket = resize_element(asn_score, total_asn, bucket)
-            rate = resize_element(asn_score, total_asn, rate)
-          elseif total_country and total_country > ip_score_lower_bound then
-            bucket = resize_element(country_score, total_country, bucket)
-            rate = resize_element(country_score, total_country, rate)
-          else
-            bucket = resize_element(ip_score, total_ip, bucket)
-            rate = resize_element(ip_score, total_ip, rate)
-          end
-        end
-      end
-
-      if atime - ctime > max_delay then
-        rspamd_logger.infox(task, 'limit is too old: %1 seconds; ignore it',
-          atime - ctime)
-      else
-        bucket = bucket - rate * (ntime - atime);
-        if bucket > 0 then
-          if ratelimit_symbol then
-            local mult = 2 * rspamd_util.tanh(bucket / (threshold * 2))
-
-            if mult > 0.5 then
-              task:insert_result(ratelimit_symbol, mult,
-                rtype .. ':' .. string.format('%.2f', mult))
-            end
-          else
-            if bucket > threshold then
-              rspamd_logger.infox(task,
-                'ratelimit "%s" exceeded: %s elements with %s limit',
-                rtype, bucket, threshold)
-              task:set_pre_result('soft reject',
-                message_func(task, rtype, bucket, threshold))
-            end
-          end
-        end
-      end
-    end, fun.zip(parse_limits(data), fun.map(function(a) return a[1] end, args),
-      fun.map(function(a) return rspamd_str_split(a[2], ":")[2] end, args)))
-  end
-
-  ret = rspamd_redis_make_request(task,
-    redis_params, -- connect params
-    key, -- hash key
-    false, -- is write
-    rate_get_cb, --callback
-    'mget', -- command
-    fun.totable(fun.map(function(l) return l[2] end, args)) -- arguments
-  )
-  if not ret then
-    rspamd_logger.errx(task, 'got error connecting to redis')
-  end
-end
-
---- Set specific limit inside redis
-local function set_limits(task, args)
-  local key = fun.foldl(function(acc, k) return acc .. k[2] end, '', args)
-  local ret, upstream
-
-  local function rate_set_cb(err)
-    if err then
-      rspamd_logger.infox(task, 'got error %s when setting ratelimit record on server %s',
-        err, upstream:get_addr())
-    end
-  end
-  local function rate_get_cb(err, data)
-    if err then
-      rspamd_logger.infox(task, 'got error while setting limit: %1', err)
-    end
-    if not data then return end
-    local ntime = rspamd_util.get_time()
-    local values = {}
-    fun.each(function(elt, limit)
-      local bucket = elt[2]
-      local rate = limit[1][2]
-      local atime = elt[1]
-      local ctime = elt[3]
-
-      if atime - ctime > max_delay then
-        rspamd_logger.infox(task, 'limit is too old: %1 seconds; start it over',
-          atime - ctime)
-        bucket = 1
-        ctime = ntime
-      else
-        if bucket > 0 then
-          bucket = bucket - rate * (ntime - atime) + 1;
-          if bucket < 0 then
-            bucket = 1
-          end
-        else
-          bucket = 1
-        end
-      end
-
-      if ctime == 0 then ctime = ntime end
-
-      local lstr = string.format('%.3f:%.3f:%.3f', ntime, bucket, ctime)
-      table.insert(values, {limit[2], max_delay, lstr})
-    end, fun.zip(parse_limits(data), fun.iter(args)))
-
-    if #values > 0 then
-      local conn
-      ret,conn,upstream = rspamd_redis_make_request(task,
-        redis_params, -- connect params
-        key, -- hash key
-        true, -- is write
-        rate_set_cb, --callback
-        'setex', -- command
-        values[1] -- arguments
-      )
-
-      if conn then
-        fun.each(function(v)
-          conn:add_cmd('setex', v)
-        end, fun.drop_n(1, values))
-      else
-        rspamd_logger.errx(task, 'got error while connecting to redis')
-      end
-    end
-  end
-
-  local _
-  ret,_,upstream = rspamd_redis_make_request(task,
-    redis_params, -- connect params
-    key, -- hash key
-    false, -- is write
-    rate_get_cb, --callback
-    'mget', -- command
-    fun.totable(fun.map(function(l) return l[2] end, args)) -- arguments
-  )
-  if not ret then
-    rspamd_logger.errx(task, 'got error connecting to redis')
-  end
-end
-
---- Check or update ratelimit
-local function rate_test_set(task, func)
+local function get_buckets(task)
   local args = {}
   -- Get initial task data
   local ip = task:get_from_ip()
@@ -509,104 +418,142 @@ local function rate_test_set(task, func)
     if rate_key then
       if type(rate_key) == 'table' then
         for _, rk in ipairs(rate_key) do
-          if type(settings[k]) == 'table' then
-            table.insert(args, {settings[k], rk})
-          elseif type(settings[k]) == 'string' and
+          if type(settings[k]) == 'string' and
               (custom_keywords[settings[k]] and type(custom_keywords[settings[k]]['get_limit']) == 'function') then
             local res = custom_keywords[settings[k]]['get_limit'](task)
-            if type(res) == 'table' then
-              table.insert(args, {res, rate_key})
-            elseif type(res) == 'string' then
-              local plim, size = parse_string_limit(res)
+            if type(res) == 'string' then res = {res} end
+            for _, r in ipairs(res) do
+              local plim, size = parse_string_limit(r)
               if plim then
-                table.insert(args, {{size, plim, 1}, rate_key})
+                table.insert(args, {{plim, size}, rk})
               end
             end
           end
         end
       else
-        if type(settings[k]) == 'table' then
-          table.insert(args, {settings[k], rate_key})
-        elseif type(settings[k]) == 'string' and
-            (custom_keywords[settings[k]] and type(custom_keywords[settings[k]]['get_limit']) == 'function') then
+        if type(settings[k]) == 'string' and
+          (custom_keywords[settings[k]] and type(custom_keywords[settings[k]]['get_limit']) == 'function') then
           local res = custom_keywords[settings[k]]['get_limit'](task)
-          if type(res) == 'table' then
-            table.insert(args, {res, rate_key})
-          elseif type(res) == 'string' then
-            local plim, size = parse_string_limit(res)
+          if type(res) == 'string' then res = {res} end
+          for _, r in ipairs(res) do
+            local plim, size = parse_string_limit(r)
             if plim then
-              table.insert(args, {{size, plim, 1}, rate_key})
+              table.insert(args, {{plim, size}, rate_key})
             end
           end
+        elseif type(settings[k]) == 'table' then
+          for _, rl in ipairs(settings[k]) do
+            table.insert(args, {{rl[1], rl[2]}, rate_key})
+          end
         end
       end
     end
   end
 
-  if #args > 0 then
-    func(task, args)
-  end
+  return args
 end
 
---- Check limit
-local function rate_test(task)
+local function ratelimit_cb(task)
   if rspamd_lua_utils.is_rspamc_or_controller(task) then return end
-  rate_test_set(task, check_limits)
-end
---- Update limit
-local function rate_set(task)
-  local action = task:get_metric_action('default')
-
-  if action ~= 'soft reject' then
-    if rspamd_lua_utils.is_rspamc_or_controller(task) then return end
-    rate_test_set(task, set_limits)
+  local function rl_redis_cb(err, data)
+    if err then
+      rspamd_logger.infox(task, 'got error while setting limit: %1', err)
+    end
+    if not data then return end
+    if data[1] == 1 then
+      rspamd_logger.infox(task,
+        'ratelimit "%s" exceeded',
+        data[2])
+      task:set_pre_result('soft reject',
+        message_func(task, data[2]))
+    end
   end
-end
-
-
---- Parse a single limit description
-local function parse_limit(str)
-  local params = rspamd_str_split(str, ':')
-
-  local function set_limit(limit, burst, rate)
-    limit[1] = tonumber(burst)
-    limit[2] = tonumber(rate)
+  local function rl_symbol_redis_cb(err, data)
+    if err then
+      rspamd_logger.infox(task, 'got error while setting limit: %1', err)
+    end
+    if not data then return end
+    for i, b in ipairs(data) do
+      task:insert_result(ratelimit_symbol, b[2], string.format('%s:%s:%s', i, b[1], b[2]))
+    end
   end
-
-  if #params ~= 3 then
-    rspamd_logger.errx(rspamd_config, 'invalid limit definition: ' .. str)
-    return
+  local redis_cb = rl_redis_cb
+  if ratelimit_symbol then redis_cb = rl_symbol_redis_cb end
+  local buckets = get_buckets(task)
+  if not buckets then return end
+  local args = {redis_script_sha, #buckets}
+  for _, bucket in ipairs(buckets) do
+    table.insert(args, bucket[2])
   end
-
-  local key_keywords = rspamd_str_split(params[1], '_')
-  for _, k in ipairs(key_keywords) do
-    if (custom_keywords[k] and type(custom_keywords[k]['get_value']) == 'function') or
-        (keywords[k] and type(keywords[k]['get_value']) == 'function') then
-      set_limit(settings[params[1]], params[2], params[3])
-    else
-      rspamd_logger.errx(rspamd_config, 'invalid limit type: ' .. params[1])
+  for _, bucket in ipairs(buckets) do
+    if use_ip_score then
+      local asn_score,total_asn,
+        country_score,total_country,
+        ipnet_score,total_ipnet,
+        ip_score, total_ip = task:get_mempool():get_variable('ip_score',
+        'double,double,double,double,double,double,double,double')
+      local key_keywords = rspamd_str_split(bucket[2], '_')
+      local has_asn, has_ip = false, false
+      for _, v in ipairs(key_keywords) do
+        if v == "asn" then has_asn = true end
+        if v == "ip" then has_ip = true end
+        if has_ip and has_asn then break end
+      end
+      if has_asn and not has_ip then
+        bucket[1][2] = resize_element(asn_score, total_asn, bucket[1][2])
+      elseif has_ip then
+        if total_ip and total_ip > ip_score_lower_bound then
+          bucket[1][2] = resize_element(ip_score, total_ip, bucket[1][2])
+        elseif total_ipnet and total_ipnet > ip_score_lower_bound then
+          bucket[1][2] = resize_element(ipnet_score, total_ipnet, bucket[1][2])
+        elseif total_asn and total_asn > ip_score_lower_bound then
+          bucket[1][2] = resize_element(asn_score, total_asn, bucket[1][2])
+        elseif total_country and total_country > ip_score_lower_bound then
+          bucket[1][2] = resize_element(country_score, total_country, bucket[1][2])
+        else
+          bucket[1][2] = resize_element(ip_score, total_ip, bucket[1][2])
+        end
+      end
     end
+    table.insert(args, bucket[1][1])
+    table.insert(args, bucket[1][2])
+  end
+  table.insert(args, rspamd_util.get_time())
+  table.insert(args, task:get_queue_id() or task:get_uid())
+  local ret = rspamd_redis_make_request(task,
+    redis_params, -- connect params
+    nil, -- hash key
+    true, -- is write
+    redis_cb, --callback
+    'evalsha', -- command
+    args -- arguments
+  )
+  if not ret then
+    rspamd_logger.errx(task, 'got error connecting to redis')
   end
 end
 
-local opts = rspamd_config:get_all_opt('ratelimit')
+local opts = rspamd_config:get_all_opt(N)
 if opts then
-  local rates = opts['limit']
-  if rates and type(rates) == 'table' then
-    fun.each(parse_limit, rates)
-  elseif rates and type(rates) == 'string' then
-    parse_limit(rates)
+  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)
       if type(lim) == 'table' then
-        settings[t] = lim
+        settings[t] = {}
+        fun.each(function(l)
+          local plim, size = parse_string_limit(l)
+          if plim then
+            table.insert(settings[t], {plim, size})
+          end
+        end, lim)
       elseif type(lim) == 'string' then
         local plim, size = parse_string_limit(lim)
         if plim then
-          settings[t] = {size, plim, 1}
+          settings[t] = { {plim, size} }
         end
       end
     end, opts['rates'])
@@ -622,11 +569,7 @@ if opts then
 
   local enabled_limits = fun.totable(fun.map(function(t)
     return t
-  end, fun.filter(function(_, lim)
-    return type(lim) == 'string' or
-        (type(lim) == 'table' and type(lim[1]) == 'number' and lim[1] > 0)
-        or (type(lim) == 'table' and (lim[3]))
-  end, settings)))
+  end, settings))
   rspamd_logger.infox(rspamd_config, 'enabled rate buckets: [%1]', table.concat(enabled_limits, ','))
 
   if opts['whitelisted_rcpts'] and type(opts['whitelisted_rcpts']) == 'string' then
@@ -654,10 +597,6 @@ if opts then
     max_rcpt = tonumber(opts['max_rcpt'])
   end
 
-  if opts['max_delay'] then
-    max_rcpt = tonumber(opts['max_delay'])
-  end
-
   if opts['use_ip_score'] then
     use_ip_score = true
     local ip_score_opts = rspamd_config:get_all_opt('ip_score')
@@ -682,35 +621,22 @@ if opts then
   if not redis_params then
     rspamd_logger.infox(rspamd_config, 'no servers are specified, disabling module')
   else
-    if not ratelimit_symbol and not use_ip_score then
-      rspamd_config:register_symbol({
-        name = 'RATELIMIT_CHECK',
-        callback = rate_test,
-        type = 'prefilter,nostat',
-        priority = 4,
-      })
-    else
-      local symbol
-      if not ratelimit_symbol then
-        symbol = 'RATELIMIT_CHECK'
-      else
-        symbol = ratelimit_symbol
-      end
-      local id = rspamd_config:register_symbol({
-        name = symbol,
-        callback = rate_test,
-        type = 'normal,nostat'
-      })
-      if use_ip_score then
-        rspamd_config:register_dependency(id, 'IP_SCORE')
-      end
+    local s = {
+      type = 'prefilter,nostat',
+      name = 'RATELIMIT_CHECK',
+      priority = 4,
+      callback = ratelimit_cb,
+    }
+    if use_ip_score then
+      s.type = 'normal'
+    end
+    if ratelimit_symbol then
+      s.name = ratelimit_symbol
+    end
+    local id = rspamd_config:register_symbol(s)
+    if use_ip_score then
+      rspamd_config:register_dependency(id, 'IP_SCORE')
     end
-    rspamd_config:register_symbol({
-      name = 'RATELIMIT_SET',
-      type = 'idempotent',
-      priority = 5,
-      callback = rate_set,
-    })
     for _, v in pairs(custom_keywords) do
       if type(v) == 'table' and type(v['init']) == 'function' then
         v['init']()
@@ -718,4 +644,6 @@ if opts then
     end
   end
 end
-
+rspamd_config:add_on_load(function(cfg, ev_base, worker)
+  load_scripts(cfg, ev_base)
+end)
-- 
2.39.5