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--[[
Copyright (c) 2019, Vsevolod Stakhov <vsevolod@highsecure.ru>
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.
]]--
local exports = {}
---[[[
-- @function lua_verdict.get_default_verdict(task)
-- Returns verdict for a task + score if certain, must be called from idempotent filters only
-- Returns string:
-- * `spam`: if message have over reject threshold and has more than one positive rule
-- * `junk`: if a message has between score between [add_header/rewrite subject] to reject thresholds and has more than two positive rules
-- * `passthrough`: if a message has been passed through some short-circuit rule
-- * `ham`: if a message has overall score below junk level **and** more than three negative rule, or negative total score
-- * `uncertain`: all other cases
--]]
local function default_verdict_function(task)
local result = task:get_metric_result()
if result then
if result.passthrough then
return 'passthrough',nil
end
local score = result.score
local action = result.action
if action == 'reject' and result.npositive > 1 then
return 'spam',score
elseif action == 'no action' then
if score < 0 or result.nnegative > 3 then
return 'ham',score
end
else
-- All colors of junk
if action == 'add header' or action == 'rewrite subject' then
if result.npositive > 2 then
return 'junk',score
end
end
end
return 'uncertain',score
end
end
local default_possible_verdicts = {
passthrough = {
can_learn = false,
description = 'message has passthrough result',
},
spam = {
can_learn = 'spam',
description = 'message is likely spam',
},
junk = {
can_learn = 'spam',
description = 'message is likely possible spam',
},
ham = {
can_learn = 'ham',
description = 'message is likely ham',
},
uncertain = {
can_learn = false,
description = 'not certainity in verdict'
}
}
-- Verdict functions specific for modules
local specific_verdicts = {
default = {
callback = default_verdict_function,
possible_verdicts = default_possible_verdicts
}
}
local default_verdict = specific_verdicts.default
exports.get_default_verdict = default_verdict.callback
exports.set_verdict_function = function(func, what)
assert(type(func) == 'function')
if not what then
-- Default verdict
local existing = specific_verdicts.default.callback
specific_verdicts.default.callback = func
exports.get_default_verdict = func
return existing
else
local existing = specific_verdicts[what]
if not existing then
specific_verdicts[what] = {
callback = func,
possible_verdicts = default_possible_verdicts
}
else
existing = existing.callback
end
specific_verdicts[what].callback = func
return existing
end
end
exports.set_verdict_table = function(verdict_tbl, what)
assert(type(verdict_tbl) == 'table' and
type(verdict_tbl.callback) == 'function' and
type(verdict_tbl.possible_verdicts) == 'table')
if not what then
-- Default verdict
local existing = specific_verdicts.default
specific_verdicts.default = verdict_tbl
exports.get_default_verdict = specific_verdicts.default.callback
return existing
else
local existing = specific_verdicts[what]
specific_verdicts[what] = verdict_tbl
return existing
end
end
exports.get_specific_verdict = function(what, task)
if specific_verdicts[what] then
return specific_verdicts[what].callback(task)
end
return exports.get_default_verdict(task)
end
exports.get_possible_verdicts = function(what)
local lua_util = require "lua_util"
if what then
if specific_verdicts[what] then
return lua_util.keys(specific_verdicts[what].possible_verdicts)
end
else
return lua_util.keys(specific_verdicts.default.possible_verdicts)
end
return nil
end
exports.can_learn = function(verdict, what)
if what then
if specific_verdicts[what] and specific_verdicts[what].possible_verdicts[verdict] then
return specific_verdicts[what].possible_verdicts[verdict].can_learn
end
else
if specific_verdicts.default.possible_verdicts[verdict] then
return specific_verdicts.default.possible_verdicts[verdict].can_learn
end
end
return nil -- To distinguish from `false` that could happen in can_learn
end
exports.describe = function(verdict, what)
if what then
if specific_verdicts[what] and specific_verdicts[what].possible_verdicts[verdict] then
return specific_verdicts[what].possible_verdicts[verdict].description
end
else
if specific_verdicts.default.possible_verdicts[verdict] then
return specific_verdicts.default.possible_verdicts[verdict].description
end
end
return nil
end
return exports
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