[Rework] Reorganise selectors implementation

1 files changed, 496 insertions, 0 deletions

diff --git a/lualib/lua_selectors/init.lua b/lualib/lua_selectors/init.lua
new file mode 100644
index 000000000..356a05509
--- /dev/null
+++ b/lualib/lua_selectors/init.lua
@@ -0,0 +1,496 @@
+--[[
+Copyright (c) 2018, 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.
+]]--
+
+-- This module contains 'selectors' implementation: code to extract data
+-- from Rspamd tasks and compose those together
+--
+-- Read more at https://rspamd.com/doc/configuration/selectors.html
+
+--[[[
+-- @module lua_selectors
+-- This module contains 'selectors' implementation: code to extract data
+-- from Rspamd tasks and compose those together.
+-- Typical selector looks like this: header(User).lower.substring(1, 2):ip
+--]]
+
+local exports = {
+  maps = require "lua_selectors/maps"
+}
+
+local logger = require 'rspamd_logger'
+local fun = require 'fun'
+local lua_util = require "lua_util"
+local M = "selectors"
+local E = {}
+
+local extractors = require "lua_scanners/extractors"
+local transform_function = require "lua_scanners/transforms"
+
+local function pure_type(ltype)
+  return ltype:match('^(.*)_list$')
+end
+
+local function process_selector(task, sel)
+  local function allowed_type(t)
+    if t == 'string' or t == 'text' or t == 'string_list' or t == 'text_list' then
+      return true
+    end
+
+    return false
+  end
+
+  local function list_type(t)
+    return pure_type(t)
+  end
+
+  local function implicit_tostring(t, ud_or_table)
+    if t == 'table' then
+      -- Table (very special)
+      if ud_or_table.value then
+        return ud_or_table.value,'string'
+      elseif ud_or_table.addr then
+        return ud_or_table.addr,'string'
+      end
+
+      return logger.slog("%s", ud_or_table),'string'
+    else
+      return tostring(ud_or_table),'string'
+    end
+  end
+
+  local input,etype = sel.selector.get_value(task, sel.selector.args)
+
+  if not input then
+    lua_util.debugm(M, task, 'no value extracted for %s', sel.selector.name)
+    return nil
+  end
+
+  lua_util.debugm(M, task, 'extracted %s, type %s',
+      sel.selector.name, etype)
+
+  local pipe = sel.processor_pipe or E
+
+  if etype:match('^userdata') or etype:match('^table') then
+    -- Apply userdata conversion first
+    local first_elt = pipe[1]
+
+    if first_elt and first_elt.method then
+      -- Explicit conversion
+      local meth = first_elt
+
+      if meth.types[etype] then
+        lua_util.debugm(M, task, 'apply method `%s` to %s',
+            meth.name, etype)
+        input,etype = meth.process(input, etype)
+      else
+        local pt = pure_type(etype)
+
+        if meth.types[pt] then
+          lua_util.debugm(M, task, 'map method `%s` to list of %s',
+              meth.name, pt)
+          -- Map method to a list of inputs, excluding empty elements
+          input = fun.filter(function(map_elt) return map_elt end,
+              fun.map(function(list_elt)
+                local ret, _ = meth.process(list_elt, pt)
+                return ret
+              end, input))
+          etype = 'string_list'
+        end
+      end
+      -- Remove method from the pipeline
+      pipe = fun.drop_n(1, pipe)
+    else
+      -- Implicit conversion
+
+      local pt = pure_type(etype)
+
+      if not pt then
+        lua_util.debugm(M, task, 'apply implicit conversion %s->string', etype)
+        input = implicit_tostring(etype, input)
+        etype = 'string'
+      else
+        lua_util.debugm(M, task, 'apply implicit map %s->string', pt)
+        input = fun.filter(function(map_elt) return map_elt end,
+            fun.map(function(list_elt)
+              local ret = implicit_tostring(pt, list_elt)
+              return ret
+            end, input))
+        etype = 'string_list'
+      end
+    end
+  end
+
+  -- Now we fold elements using left fold
+  local function fold_function(acc, x)
+    if acc == nil or acc[1] == nil then
+      lua_util.debugm(M, task, 'do not apply %s, accumulator is nil', x.name)
+      return nil
+    end
+
+    local value = acc[1]
+    local t = acc[2]
+
+    if not x.types[t] then
+      local pt = pure_type(t)
+
+      if pt and x.types['list'] then
+        -- Generic list processor
+        lua_util.debugm(M, task, 'apply list function `%s` to %s', x.name, t)
+        return {x.process(value, t, x.args)}
+      elseif pt and x.map_type and x.types[pt] then
+        local map_type = x.map_type .. '_list'
+        lua_util.debugm(M, task, 'map `%s` to list of %s resulting %s',
+            x.name, pt, map_type)
+        -- Apply map, filtering empty values
+        return {
+          fun.filter(function(map_elt) return map_elt end,
+              fun.map(function(list_elt)
+                if not list_elt then return nil end
+                local ret, _ = x.process(list_elt, pt, x.args)
+                return ret
+              end, value)),
+          map_type -- Returned type
+        }
+      end
+      logger.errx(task, 'cannot apply transform %s for type %s', x.name, t)
+      return nil
+    end
+
+    lua_util.debugm(M, task, 'apply %s to %s', x.name, t)
+    return {x.process(value, t, x.args)}
+  end
+
+  local res = fun.foldl(fold_function,
+      {input, etype},
+      pipe)
+
+  if not res or not res[1] then return nil end -- Pipeline failed
+
+  if not allowed_type(res[2]) then
+
+    -- Search for implicit conversion
+    local pt = pure_type(res[2])
+
+    if pt then
+      lua_util.debugm(M, task, 'apply implicit map %s->string_list', pt)
+      res[1] = fun.map(function(e) return implicit_tostring(pt, e) end, res[1])
+      res[2] = 'string_list'
+    else
+      res[1] = implicit_tostring(res[2], res[1])
+      res[2] = 'string'
+    end
+  end
+
+  if list_type(res[2]) then
+    -- Convert to table as it might have a functional form
+    res[1] = fun.totable(res[1])
+  end
+
+  lua_util.debugm(M, task, 'final selector type: %s, value: %s', res[2], res[1])
+
+  return res[1]
+end
+
+local function make_grammar()
+  local l = require "lpeg"
+  local spc = l.S(" \t\n")^0
+  local atom = l.C((l.R("az") + l.R("AZ") + l.R("09") + l.S("_-"))^1)
+  local singlequoted_string = l.P "'" * l.C(((1 - l.S "'\r\n\f\\") + (l.P'\\' * 1))^0) * "'"
+  local doublequoted_string = l.P '"' * l.C(((1 - l.S'"\r\n\f\\') + (l.P'\\' * 1))^0) * '"'
+  local argument = atom + singlequoted_string + doublequoted_string
+  local dot = l.P(".")
+  local semicolon = l.P(":")
+  local obrace = "(" * spc
+  local ebrace = spc * ")"
+  local comma = spc * "," * spc
+  local sel_separator = spc * l.S";*" * spc
+
+  return l.P{
+    "LIST";
+    LIST = l.Ct(l.V("EXPR")) * (sel_separator * l.Ct(l.V("EXPR")))^0,
+    EXPR = l.V("FUNCTION") * (semicolon * l.V("METHOD"))^-1 * (dot * l.V("PROCESSOR"))^0,
+    PROCESSOR = l.Ct(atom * spc * (obrace * l.V("ARG_LIST") * ebrace)^0),
+    FUNCTION = l.Ct(atom * spc * (obrace * l.V("ARG_LIST") * ebrace)^0),
+    METHOD = l.Ct(atom / function(e) return '__' .. e end * spc * (obrace * l.V("ARG_LIST") * ebrace)^0),
+    ARG_LIST = l.Ct((argument * comma^0)^0)
+  }
+end
+
+local parser = make_grammar()
+
+--[[[
+-- @function lua_selectors.parse_selector(cfg, str)
+--]]
+exports.parse_selector = function(cfg, str)
+  local parsed = {parser:match(str)}
+  local output = {}
+
+  if not parsed or not parsed[1] then return nil end
+
+  local function check_args(name, schema, args)
+    if schema then
+      if getmetatable(schema) then
+        -- Schema covers all arguments
+        local res,err = schema:transform(args)
+        if not res then
+          logger.errx(rspamd_config, 'invalid arguments for %s: %s', name, err)
+          return false
+        else
+          for i,elt in ipairs(res) do
+            args[i] = elt
+          end
+        end
+      else
+        for i,selt in ipairs(schema) do
+          local res,err = selt:transform(args[i])
+
+          if err then
+            logger.errx(rspamd_config, 'invalid arguments for %s: %s', name, err)
+            return false
+          else
+            args[i] = res
+          end
+        end
+      end
+    end
+
+    return true
+  end
+
+  -- Output AST format is the following:
+  -- table of individual selectors
+  -- each selector: list of functions
+  -- each function: function name + optional list of arguments
+  for _,sel in ipairs(parsed) do
+    local res = {
+      selector = {},
+      processor_pipe = {},
+    }
+
+    local selector_tbl = sel[1]
+    if not selector_tbl then
+      logger.errx(cfg, 'no selector represented')
+      return nil
+    end
+    if not extractors[selector_tbl[1]] then
+      logger.errx(cfg, 'selector %s is unknown', selector_tbl[1])
+      return nil
+    end
+
+    res.selector = lua_util.shallowcopy(extractors[selector_tbl[1]])
+    res.selector.name = selector_tbl[1]
+    res.selector.args = selector_tbl[2] or E
+
+    if not check_args(res.selector.name,
+        res.selector.args_schema,
+        res.selector.args) then
+      return nil
+    end
+
+    lua_util.debugm(M, cfg, 'processed selector %s, args: %s',
+        res.selector.name, res.selector.args)
+
+    local pipeline_error = false
+    -- Now process processors pipe
+    fun.each(function(proc_tbl)
+      local proc_name = proc_tbl[1]
+
+      if proc_name:match('^__') then
+        -- Special case - method
+        local method_name = proc_name:match('^__(.*)$')
+        -- Check array indexing...
+        if tonumber(method_name) then
+          method_name = tonumber(method_name)
+        end
+        local processor = {
+          name = tostring(method_name),
+          method = true,
+          args = proc_tbl[2] or E,
+          types = {
+            userdata = true,
+            table = true,
+          },
+          map_type = 'string',
+          process = function(inp, t, args)
+            if t == 'userdata' then
+              return inp[method_name](inp, args),'string'
+            else
+              -- Table
+              return inp[method_name],'string'
+            end
+          end,
+        }
+        lua_util.debugm(M, cfg, 'attached method %s to selector %s, args: %s',
+            proc_name, res.selector.name, processor.args)
+        table.insert(res.processor_pipe, processor)
+      else
+
+        if not transform_function[proc_name] then
+          logger.errx(cfg, 'processor %s is unknown', proc_name)
+          pipeline_error = proc_name
+          return nil
+        end
+        local processor = lua_util.shallowcopy(transform_function[proc_name])
+        processor.name = proc_name
+        processor.args = proc_tbl[2] or E
+
+        if not check_args(processor.name, processor.args_schema, processor.args) then
+          pipeline_error = 'args schema for ' .. proc_name
+          return nil
+        end
+
+        lua_util.debugm(M, cfg, 'attached processor %s to selector %s, args: %s',
+            proc_name, res.selector.name, processor.args)
+        table.insert(res.processor_pipe, processor)
+      end
+    end, fun.tail(sel))
+
+    if pipeline_error then
+      logger.errx(cfg, 'unknown or invalid processor used: "%s", exiting', pipeline_error)
+      return nil
+    end
+
+    table.insert(output, res)
+  end
+
+  return output
+end
+
+--[[[
+-- @function lua_selectors.register_extractor(cfg, name, selector)
+--]]
+exports.register_extractor = function(cfg, name, selector)
+  if selector.get_value then
+    if extractors[name] then
+      logger.warnx(cfg, 'redefining selector %s', name)
+    end
+    extractors[name] = selector
+
+    return true
+  end
+
+  logger.errx(cfg, 'bad selector %s', name)
+  return false
+end
+
+--[[[
+-- @function lua_selectors.register_transform(cfg, name, transform)
+--]]
+exports.register_transform = function(cfg, name, transform)
+  if transform.process and transform.types then
+    if transform_function[name] then
+      logger.warnx(cfg, 'redefining transform function %s', name)
+    end
+    transform_function[name] = transform
+
+    return true
+  end
+
+  logger.errx(cfg, 'bad transform function %s', name)
+  return false
+end
+
+--[[[
+-- @function lua_selectors.process_selectors(task, selectors_pipe)
+--]]
+exports.process_selectors = function(task, selectors_pipe)
+  local ret = {}
+
+  for _,sel in ipairs(selectors_pipe) do
+    local r = process_selector(task, sel)
+
+    -- If any element is nil, then the whole selector is nil
+    if not r then return nil end
+    table.insert(ret, r)
+  end
+
+  return ret
+end
+
+--[[[
+-- @function lua_selectors.combine_selectors(task, selectors, delimiter)
+--]]
+exports.combine_selectors = function(_, selectors, delimiter)
+  if not delimiter then delimiter = '' end
+
+  if not selectors then return nil end
+
+  local all_strings = fun.all(function(s) return type(s) == 'string' end, selectors)
+
+  if all_strings then
+    return table.concat(selectors, delimiter)
+  else
+    -- We need to do a spill on each table selector
+    -- e.g. s:tbl:s -> s:telt1:s + s:telt2:s ...
+    local tbl = {}
+    local res = {}
+
+    for i,s in ipairs(selectors) do
+      if type(s) == 'string' then
+        rawset(tbl, i, fun.duplicate(s))
+      elseif type(s) == 'userdata' then
+        rawset(tbl, i, fun.duplicate(tostring(s)))
+      else
+        rawset(tbl, i, s)
+      end
+    end
+
+    fun.each(function(...)
+      table.insert(res, table.concat({...}, delimiter))
+    end, fun.zip(lua_util.unpack(tbl)))
+
+    return res
+  end
+end
+
+--[[[
+-- @function lua_selectors.create_closure(cfg, selector_str, delimiter='')
+--]]
+exports.create_selector_closure = function(cfg, selector_str, delimiter)
+  local selector = exports.parse_selector(cfg, selector_str)
+
+  if not selector then
+    return nil
+  end
+
+  return function(task)
+    local res = exports.process_selectors(task, selector)
+
+    if res then
+      return exports.combine_selectors(nil, res, delimiter)
+    end
+
+    return nil
+  end
+end
+
+local function display_selectors(tbl)
+  return fun.tomap(fun.map(function(k,v)
+    return k, fun.tomap(fun.filter(function(kk, vv)
+      return type(vv) ~= 'function'
+    end, v))
+  end, tbl))
+end
+
+exports.list_extractors = function()
+  return display_selectors(extractors)
+end
+
+exports.list_transforms = function()
+  return display_selectors(transform_function)
+end
+
+return exports