diff --git a/Makefile b/Makefile
index 3a7b26ebe5b3b..cccdafe1c5908 100644
--- a/Makefile
+++ b/Makefile
@@ -318,13 +318,15 @@ $(TARGET): $(ODIR) $(DDIR) $(OBJS)
 	$(LD) $(W32FLAGS) -o $(TARGET) $(DEFINES) $(CXXFLAGS) \
           $(OBJS) $(LDFLAGS)
 
-.PHONY: version
+.PHONY: version verifyjson
 version:
 	@( VERSION_STRING=$(VERSION) ; \
             [ -e ".git" ] && GITVERSION=$$( git describe --tags --always --dirty --match "[0-9A-Z]*.[0-9A-Z]*" ) && VERSION_STRING=$$GITVERSION ; \
             [ -e "$(SRC_DIR)/version.h" ] && OLDVERSION=$$(grep VERSION $(SRC_DIR)/version.h|cut -d '"' -f2) ; \
             if [ "x$$VERSION_STRING" != "x$$OLDVERSION" ]; then echo "#define VERSION \"$$VERSION_STRING\"" | tee $(SRC_DIR)/version.h ; fi \
          )
+verifyjson:
+	lua lua/json_verifier.lua
 
 $(ODIR):
 	mkdir -p $(ODIR)
diff --git a/lua/dkjson.lua b/lua/dkjson.lua
new file mode 100644
index 0000000000000..b7475ba180ff8
--- /dev/null
+++ b/lua/dkjson.lua
@@ -0,0 +1,843 @@
+    -- Module options:
+    local always_try_using_lpeg = true
+    local register_global_module_table = false
+    local global_module_name = 'json'
+
+    --[==[
+
+David Kolf's JSON module for Lua 5.1/5.2
+========================================
+
+*Version 2.4*
+
+In the default configuration this module writes no global values, not even
+the module table. Import it using
+
+    json = require ("dkjson")
+
+In environments where `require` or a similiar function are not available
+and you cannot receive the return value of the module, you can set the
+option `register_global_module_table` to `true`.  The module table will
+then be saved in the global variable with the name given by the option
+`global_module_name`.
+
+Exported functions and values:
+
+`json.encode (object [, state])`
+--------------------------------
+
+Create a string representing the object. `Object` can be a table,
+a string, a number, a boolean, `nil`, `json.null` or any object with
+a function `__tojson` in its metatable. A table can only use strings
+and numbers as keys and its values have to be valid objects as
+well. It raises an error for any invalid data types or reference
+cycles.
+
+`state` is an optional table with the following fields:
+
+  - `indent`  
+    When `indent` (a boolean) is set, the created string will contain
+    newlines and indentations. Otherwise it will be one long line.
+  - `keyorder`  
+    `keyorder` is an array to specify the ordering of keys in the
+    encoded output. If an object has keys which are not in this array
+    they are written after the sorted keys.
+  - `level`  
+    This is the initial level of indentation used when `indent` is
+    set. For each level two spaces are added. When absent it is set
+    to 0.
+  - `buffer`  
+    `buffer` is an array to store the strings for the result so they
+    can be concatenated at once. When it isn't given, the encode
+    function will create it temporary and will return the
+    concatenated result.
+  - `bufferlen`  
+    When `bufferlen` is set, it has to be the index of the last
+    element of `buffer`.
+  - `tables`  
+    `tables` is a set to detect reference cycles. It is created
+    temporary when absent. Every table that is currently processed
+    is used as key, the value is `true`.
+
+When `state.buffer` was set, the return value will be `true` on
+success. Without `state.buffer` the return value will be a string.
+
+`json.decode (string [, position [, null]])`
+--------------------------------------------
+
+Decode `string` starting at `position` or at 1 if `position` was
+omitted.
+
+`null` is an optional value to be returned for null values. The
+default is `nil`, but you could set it to `json.null` or any other
+value.
+
+The return values are the object or `nil`, the position of the next
+character that doesn't belong to the object, and in case of errors
+an error message.
+
+Two metatables are created. Every array or object that is decoded gets
+a metatable with the `__jsontype` field set to either `array` or
+`object`. If you want to provide your own metatables use the syntax
+
+    json.decode (string, position, null, objectmeta, arraymeta)
+
+To prevent the assigning of metatables pass `nil`:
+
+    json.decode (string, position, null, nil)
+
+`<metatable>.__jsonorder`
+-------------------------
+
+`__jsonorder` can overwrite the `keyorder` for a specific table.
+
+`<metatable>.__jsontype`
+------------------------
+
+`__jsontype` can be either `"array"` or `"object"`. This value is only
+checked for empty tables. (The default for empty tables is `"array"`).
+
+`<metatable>.__tojson (self, state)`
+------------------------------------
+
+You can provide your own `__tojson` function in a metatable. In this
+function you can either add directly to the buffer and return true,
+or you can return a string. On errors nil and a message should be
+returned.
+
+`json.null`
+-----------
+
+You can use this value for setting explicit `null` values.
+
+`json.version`
+--------------
+
+Set to `"dkjson 2.4"`.
+
+`json.quotestring (string)`
+---------------------------
+
+Quote a UTF-8 string and escape critical characters using JSON
+escape sequences. This function is only necessary when you build
+your own `__tojson` functions.
+
+`json.addnewline (state)`
+-------------------------
+
+When `state.indent` is set, add a newline to `state.buffer` and spaces
+according to `state.level`.
+
+LPeg support
+------------
+
+When the local configuration variable `always_try_using_lpeg` is set,
+this module tries to load LPeg to replace the `decode` function. The
+speed increase is significant. You can get the LPeg module at
+  <http://www.inf.puc-rio.br/~roberto/lpeg/>.
+When LPeg couldn't be loaded, the pure Lua functions stay active.
+
+In case you don't want this module to require LPeg on its own,
+disable the option `always_try_using_lpeg` in the options section at
+the top of the module.
+
+In this case you can later load LPeg support using
+
+### `json.use_lpeg ()`
+
+Require the LPeg module and replace the functions `quotestring` and
+and `decode` with functions that use LPeg patterns.
+This function returns the module table, so you can load the module
+using:
+
+    json = require "dkjson".use_lpeg()
+
+Alternatively you can use `pcall` so the JSON module still works when
+LPeg isn't found.
+
+    json = require "dkjson"
+    pcall (json.use_lpeg)
+
+### `json.using_lpeg`
+
+This variable is set to `true` when LPeg was loaded successfully.
+
+---------------------------------------------------------------------
+
+Contact
+-------
+
+You can contact the author by sending an e-mail to 'david' at the
+domain 'dkolf.de'.
+
+---------------------------------------------------------------------
+
+*Copyright (C) 2010-2013 David Heiko Kolf*
+
+Permission is hereby granted, free of charge, to any person obtaining
+a copy of this software and associated documentation files (the
+"Software"), to deal in the Software without restriction, including
+without limitation the rights to use, copy, modify, merge, publish,
+distribute, sublicense, and/or sell copies of the Software, and to
+permit persons to whom the Software is furnished to do so, subject to
+the following conditions:
+
+The above copyright notice and this permission notice shall be
+included in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
+
+<!-- This documentation can be parsed using Markdown to generate HTML.
+     The source code is enclosed in a HTML comment so it won't be displayed
+     by browsers, but it should be removed from the final HTML file as
+     it isn't a valid HTML comment (and wastes space).
+  -->
+
+<!--]==]
+
+-- global dependencies:
+local pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset =
+      pairs, type, tostring, tonumber, getmetatable, setmetatable, rawset
+local error, require, pcall, select = error, require, pcall, select
+local floor, huge = math.floor, math.huge
+local strrep, gsub, strsub, strbyte, strchar, strfind, strlen, strformat =
+      string.rep, string.gsub, string.sub, string.byte, string.char,
+      string.find, string.len, string.format
+local strmatch = string.match
+local concat = table.concat
+
+local json = { version = "dkjson 2.4" }
+
+if register_global_module_table then
+  _G[global_module_name] = json
+end
+
+local _ENV = nil -- blocking globals in Lua 5.2
+
+pcall (function()
+  -- Enable access to blocked metatables.
+  -- Don't worry, this module doesn't change anything in them.
+  local debmeta = require "debug".getmetatable
+  if debmeta then getmetatable = debmeta end
+end)
+
+json.null = setmetatable ({}, {
+  __tojson = function () return "null" end
+})
+
+local function isarray (tbl)
+  local max, n, arraylen = 0, 0, 0
+  for k,v in pairs (tbl) do
+    if k == 'n' and type(v) == 'number' then
+      arraylen = v
+      if v > max then
+        max = v
+      end
+    else
+      if type(k) ~= 'number' or k < 1 or floor(k) ~= k then
+        return false
+      end
+      if k > max then
+        max = k
+      end
+      n = n + 1
+    end
+  end
+  if max > 10 and max > arraylen and max > n * 2 then
+    return false -- don't create an array with too many holes
+  end
+  return true, max
+end
+
+local escapecodes = {
+  ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f",
+  ["\n"] = "\\n",  ["\r"] = "\\r",  ["\t"] = "\\t"
+}
+
+local function escapeutf8 (uchar)
+  local value = escapecodes[uchar]
+  if value then
+    return value
+  end
+  local a, b, c, d = strbyte (uchar, 1, 4)
+  a, b, c, d = a or 0, b or 0, c or 0, d or 0
+  if a <= 0x7f then
+    value = a
+  elseif 0xc0 <= a and a <= 0xdf and b >= 0x80 then
+    value = (a - 0xc0) * 0x40 + b - 0x80
+  elseif 0xe0 <= a and a <= 0xef and b >= 0x80 and c >= 0x80 then
+    value = ((a - 0xe0) * 0x40 + b - 0x80) * 0x40 + c - 0x80
+  elseif 0xf0 <= a and a <= 0xf7 and b >= 0x80 and c >= 0x80 and d >= 0x80 then
+    value = (((a - 0xf0) * 0x40 + b - 0x80) * 0x40 + c - 0x80) * 0x40 + d - 0x80
+  else
+    return ""
+  end
+  if value <= 0xffff then
+    return strformat ("\\u%.4x", value)
+  elseif value <= 0x10ffff then
+    -- encode as UTF-16 surrogate pair
+    value = value - 0x10000
+    local highsur, lowsur = 0xD800 + floor (value/0x400), 0xDC00 + (value % 0x400)
+    return strformat ("\\u%.4x\\u%.4x", highsur, lowsur)
+  else
+    return ""
+  end
+end
+
+local function fsub (str, pattern, repl)
+  -- gsub always builds a new string in a buffer, even when no match
+  -- exists. First using find should be more efficient when most strings
+  -- don't contain the pattern.
+  if strfind (str, pattern) then
+    return gsub (str, pattern, repl)
+  else
+    return str
+  end
+end
+
+local function quotestring (value)
+  -- based on the regexp "escapable" in https://github.com/douglascrockford/JSON-js
+  value = fsub (value, "[%z\1-\31\"\\\127]", escapeutf8)
+  if strfind (value, "[\194\216\220\225\226\239]") then
+    value = fsub (value, "\194[\128-\159\173]", escapeutf8)
+    value = fsub (value, "\216[\128-\132]", escapeutf8)
+    value = fsub (value, "\220\143", escapeutf8)
+    value = fsub (value, "\225\158[\180\181]", escapeutf8)
+    value = fsub (value, "\226\128[\140-\143\168-\175]", escapeutf8)
+    value = fsub (value, "\226\129[\160-\175]", escapeutf8)
+    value = fsub (value, "\239\187\191", escapeutf8)
+    value = fsub (value, "\239\191[\176-\191]", escapeutf8)
+  end
+  return "\"" .. value .. "\""
+end
+json.quotestring = quotestring
+
+local function replace(str, o, n)
+  local i, j = strfind (str, o, 1, true)
+  if i then
+    return strsub(str, 1, i-1) .. n .. strsub(str, j+1, -1)
+  else
+    return str
+  end
+end
+
+-- locale independent num2str and str2num functions
+local decpoint, numfilter
+
+local function updatedecpoint ()
+  decpoint = strmatch(tostring(0.5), "([^05+])")
+  -- build a filter that can be used to remove group separators
+  numfilter = "[^0-9%-%+eE" .. gsub(decpoint, "[%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%0") .. "]+"
+end
+
+updatedecpoint()
+
+local function num2str (num)
+  return replace(fsub(tostring(num), numfilter, ""), decpoint, ".")
+end
+
+local function str2num (str)
+  local num = tonumber(replace(str, ".", decpoint))
+  if not num then
+    updatedecpoint()
+    num = tonumber(replace(str, ".", decpoint))
+  end
+  return num
+end
+
+local function addnewline2 (level, buffer, buflen)
+  buffer[buflen+1] = "\n"
+  buffer[buflen+2] = strrep ("  ", level)
+  buflen = buflen + 2
+  return buflen
+end
+
+function json.addnewline (state)
+  if state.indent then
+    state.bufferlen = addnewline2 (state.level or 0,
+                           state.buffer, state.bufferlen or #(state.buffer))
+  end
+end
+
+local encode2 -- forward declaration
+
+local function addpair (key, value, prev, indent, level, buffer, buflen, tables, globalorder)
+  local kt = type (key)
+  if kt ~= 'string' and kt ~= 'number' then
+    return nil, "type '" .. kt .. "' is not supported as a key by JSON."
+  end
+  if prev then
+    buflen = buflen + 1
+    buffer[buflen] = ","
+  end
+  if indent then
+    buflen = addnewline2 (level, buffer, buflen)
+  end
+  buffer[buflen+1] = quotestring (key)
+  buffer[buflen+2] = ":"
+  return encode2 (value, indent, level, buffer, buflen + 2, tables, globalorder)
+end
+
+encode2 = function (value, indent, level, buffer, buflen, tables, globalorder)
+  local valtype = type (value)
+  local valmeta = getmetatable (value)
+  valmeta = type (valmeta) == 'table' and valmeta -- only tables
+  local valtojson = valmeta and valmeta.__tojson
+  if valtojson then
+    if tables[value] then
+      return nil, "reference cycle"
+    end
+    tables[value] = true
+    local state = {
+        indent = indent, level = level, buffer = buffer,
+        bufferlen = buflen, tables = tables, keyorder = globalorder
+    }
+    local ret, msg = valtojson (value, state)
+    if not ret then return nil, msg end
+    tables[value] = nil
+    buflen = state.bufferlen
+    if type (ret) == 'string' then
+      buflen = buflen + 1
+      buffer[buflen] = ret
+    end
+  elseif value == nil then
+    buflen = buflen + 1
+    buffer[buflen] = "null"
+  elseif valtype == 'number' then
+    local s
+    if value ~= value or value >= huge or -value >= huge then
+      -- This is the behaviour of the original JSON implementation.
+      s = "null"
+    else
+      s = num2str (value)
+    end
+    buflen = buflen + 1
+    buffer[buflen] = s
+  elseif valtype == 'boolean' then
+    buflen = buflen + 1
+    buffer[buflen] = value and "true" or "false"
+  elseif valtype == 'string' then
+    buflen = buflen + 1
+    buffer[buflen] = quotestring (value)
+  elseif valtype == 'table' then
+    if tables[value] then
+      return nil, "reference cycle"
+    end
+    tables[value] = true
+    level = level + 1
+    local isa, n = isarray (value)
+    if n == 0 and valmeta and valmeta.__jsontype == 'object' then
+      isa = false
+    end
+    local msg
+    if isa then -- JSON array
+      buflen = buflen + 1
+      buffer[buflen] = "["
+      for i = 1, n do
+        buflen, msg = encode2 (value[i], indent, level, buffer, buflen, tables, globalorder)
+        if not buflen then return nil, msg end
+        if i < n then
+          buflen = buflen + 1
+          buffer[buflen] = ","
+        end
+      end
+      buflen = buflen + 1
+      buffer[buflen] = "]"
+    else -- JSON object
+      local prev = false
+      buflen = buflen + 1
+      buffer[buflen] = "{"
+      local order = valmeta and valmeta.__jsonorder or globalorder
+      if order then
+        local used = {}
+        n = #order
+        for i = 1, n do
+          local k = order[i]
+          local v = value[k]
+          if v then
+            used[k] = true
+            buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder)
+            prev = true -- add a seperator before the next element
+          end
+        end
+        for k,v in pairs (value) do
+          if not used[k] then
+            buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder)
+            if not buflen then return nil, msg end
+            prev = true -- add a seperator before the next element
+          end
+        end
+      else -- unordered
+        for k,v in pairs (value) do
+          buflen, msg = addpair (k, v, prev, indent, level, buffer, buflen, tables, globalorder)
+          if not buflen then return nil, msg end
+          prev = true -- add a seperator before the next element
+        end
+      end
+      if indent then
+        buflen = addnewline2 (level - 1, buffer, buflen)
+      end
+      buflen = buflen + 1
+      buffer[buflen] = "}"
+    end
+    tables[value] = nil
+  else
+    return nil, "type '" .. valtype .. "' is not supported by JSON."
+  end
+  return buflen
+end
+
+function json.encode (value, state)
+  state = state or {}
+  local oldbuffer = state.buffer
+  local buffer = oldbuffer or {}
+  updatedecpoint()
+  local ret, msg = encode2 (value, state.indent, state.level or 0,
+                   buffer, state.bufferlen or 0, state.tables or {}, state.keyorder)
+  if not ret then
+    error (msg, 2)
+  elseif oldbuffer then
+    state.bufferlen = ret
+    return true
+  else
+    return concat (buffer)
+  end
+end
+
+local function loc (str, where)
+  local line, pos, linepos = 1, 1, 0
+  while true do
+    pos = strfind (str, "\n", pos, true)
+    if pos and pos < where then
+      line = line + 1
+      linepos = pos
+      pos = pos + 1
+    else
+      break
+    end
+  end
+  return "line " .. line .. ", column " .. (where - linepos)
+end
+
+local function unterminated (str, what, where)
+  return nil, strlen (str) + 1, "unterminated " .. what .. " at " .. loc (str, where)
+end
+
+local function scanwhite (str, pos)
+  while true do
+    pos = strfind (str, "%S", pos)
+    if not pos then return nil end
+    if strsub (str, pos, pos + 2) == "\239\187\191" then
+      -- UTF-8 Byte Order Mark
+      pos = pos + 3
+    else
+      return pos
+    end
+  end
+end
+
+local escapechars = {
+  ["\""] = "\"", ["\\"] = "\\", ["/"] = "/", ["b"] = "\b", ["f"] = "\f",
+  ["n"] = "\n", ["r"] = "\r", ["t"] = "\t"
+}
+
+local function unichar (value)
+  if value < 0 then
+    return nil
+  elseif value <= 0x007f then
+    return strchar (value)
+  elseif value <= 0x07ff then
+    return strchar (0xc0 + floor(value/0x40),
+                    0x80 + (floor(value) % 0x40))
+  elseif value <= 0xffff then
+    return strchar (0xe0 + floor(value/0x1000),
+                    0x80 + (floor(value/0x40) % 0x40),
+                    0x80 + (floor(value) % 0x40))
+  elseif value <= 0x10ffff then
+    return strchar (0xf0 + floor(value/0x40000),
+                    0x80 + (floor(value/0x1000) % 0x40),
+                    0x80 + (floor(value/0x40) % 0x40),
+                    0x80 + (floor(value) % 0x40))
+  else
+    return nil
+  end
+end
+
+local function scanstring (str, pos)
+  local lastpos = pos + 1
+  local buffer, n = {}, 0
+  while true do
+    local nextpos = strfind (str, "[\"\\]", lastpos)
+    if not nextpos then
+      return unterminated (str, "string", pos)
+    end
+    if nextpos > lastpos then
+      n = n + 1
+      buffer[n] = strsub (str, lastpos, nextpos - 1)
+    end
+    if strsub (str, nextpos, nextpos) == "\"" then
+      lastpos = nextpos + 1
+      break
+    else
+      local escchar = strsub (str, nextpos + 1, nextpos + 1)
+      local value
+      if escchar == "u" then
+        value = tonumber (strsub (str, nextpos + 2, nextpos + 5), 16)
+        if value then
+          local value2
+          if 0xD800 <= value and value <= 0xDBff then
+            -- we have the high surrogate of UTF-16. Check if there is a
+            -- low surrogate escaped nearby to combine them.
+            if strsub (str, nextpos + 6, nextpos + 7) == "\\u" then
+              value2 = tonumber (strsub (str, nextpos + 8, nextpos + 11), 16)
+              if value2 and 0xDC00 <= value2 and value2 <= 0xDFFF then
+                value = (value - 0xD800)  * 0x400 + (value2 - 0xDC00) + 0x10000
+              else
+                value2 = nil -- in case it was out of range for a low surrogate
+              end
+            end
+          end
+          value = value and unichar (value)
+          if value then
+            if value2 then
+              lastpos = nextpos + 12
+            else
+              lastpos = nextpos + 6
+            end
+          end
+        end
+      end
+      if not value then
+        value = escapechars[escchar] or escchar
+        lastpos = nextpos + 2
+      end
+      n = n + 1
+      buffer[n] = value
+    end
+  end
+  if n == 1 then
+    return buffer[1], lastpos
+  elseif n > 1 then
+    return concat (buffer), lastpos
+  else
+    return "", lastpos
+  end
+end
+
+local scanvalue -- forward declaration
+
+local function scantable (what, closechar, str, startpos, nullval, objectmeta, arraymeta)
+  local len = strlen (str)
+  local tbl, n = {}, 0
+  local pos = startpos + 1
+  if what == 'object' then
+    setmetatable (tbl, objectmeta)
+  else
+    setmetatable (tbl, arraymeta)
+  end
+  while true do
+    pos = scanwhite (str, pos)
+    if not pos then return unterminated (str, what, startpos) end
+    local char = strsub (str, pos, pos)
+    if char == closechar then
+      return tbl, pos + 1
+    end
+    local val1, err
+    val1, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta)
+    if err then return nil, pos, err end
+    pos = scanwhite (str, pos)
+    if not pos then return unterminated (str, what, startpos) end
+    char = strsub (str, pos, pos)
+    if char == ":" then
+      if val1 == nil then
+        return nil, pos, "cannot use nil as table index (at " .. loc (str, pos) .. ")"
+      end
+      pos = scanwhite (str, pos + 1)
+      if not pos then return unterminated (str, what, startpos) end
+      local val2
+      val2, pos, err = scanvalue (str, pos, nullval, objectmeta, arraymeta)
+      if err then return nil, pos, err end
+      tbl[val1] = val2
+      pos = scanwhite (str, pos)
+      if not pos then return unterminated (str, what, startpos) end
+      char = strsub (str, pos, pos)
+    else
+      n = n + 1
+      tbl[n] = val1
+    end
+    if char == "," then
+      pos = pos + 1
+    end
+  end
+end
+
+scanvalue = function (str, pos, nullval, objectmeta, arraymeta)
+  pos = pos or 1
+  pos = scanwhite (str, pos)
+  if not pos then
+    return nil, strlen (str) + 1, "no valid JSON value (reached the end)"
+  end
+  local char = strsub (str, pos, pos)
+  if char == "{" then
+    return scantable ('object', "}", str, pos, nullval, objectmeta, arraymeta)
+  elseif char == "[" then
+    return scantable ('array', "]", str, pos, nullval, objectmeta, arraymeta)
+  elseif char == "\"" then
+    return scanstring (str, pos)
+  else
+    local pstart, pend = strfind (str, "^%-?[%d%.]+[eE]?[%+%-]?%d*", pos)
+    if pstart then
+      local number = str2num (strsub (str, pstart, pend))
+      if number then
+        return number, pend + 1
+      end
+    end
+    pstart, pend = strfind (str, "^%a%w*", pos)
+    if pstart then
+      local name = strsub (str, pstart, pend)
+      if name == "true" then
+        return true, pend + 1
+      elseif name == "false" then
+        return false, pend + 1
+      elseif name == "null" then
+        return nullval, pend + 1
+      end
+    end
+    return nil, pos, "no valid JSON value at " .. loc (str, pos)
+  end
+end
+
+local function optionalmetatables(...)
+  if select("#", ...) > 0 then
+    return ...
+  else
+    return {__jsontype = 'object'}, {__jsontype = 'array'}
+  end
+end
+
+function json.decode (str, pos, nullval, ...)
+  local objectmeta, arraymeta = optionalmetatables(...)
+  return scanvalue (str, pos, nullval, objectmeta, arraymeta)
+end
+
+function json.use_lpeg ()
+  local g = require ("lpeg")
+
+  if g.version() == "0.11" then
+    error "due to a bug in LPeg 0.11, it cannot be used for JSON matching"
+  end
+
+  local pegmatch = g.match
+  local P, S, R = g.P, g.S, g.R
+
+  local function ErrorCall (str, pos, msg, state)
+    if not state.msg then
+      state.msg = msg .. " at " .. loc (str, pos)
+      state.pos = pos
+    end
+    return false
+  end
+
+  local function Err (msg)
+    return g.Cmt (g.Cc (msg) * g.Carg (2), ErrorCall)
+  end
+
+  local Space = (S" \n\r\t" + P"\239\187\191")^0
+
+  local PlainChar = 1 - S"\"\\\n\r"
+  local EscapeSequence = (P"\\" * g.C (S"\"\\/bfnrt" + Err "unsupported escape sequence")) / escapechars
+  local HexDigit = R("09", "af", "AF")
+  local function UTF16Surrogate (match, pos, high, low)
+    high, low = tonumber (high, 16), tonumber (low, 16)
+    if 0xD800 <= high and high <= 0xDBff and 0xDC00 <= low and low <= 0xDFFF then
+      return true, unichar ((high - 0xD800)  * 0x400 + (low - 0xDC00) + 0x10000)
+    else
+      return false
+    end
+  end
+  local function UTF16BMP (hex)
+    return unichar (tonumber (hex, 16))
+  end
+  local U16Sequence = (P"\\u" * g.C (HexDigit * HexDigit * HexDigit * HexDigit))
+  local UnicodeEscape = g.Cmt (U16Sequence * U16Sequence, UTF16Surrogate) + U16Sequence/UTF16BMP
+  local Char = UnicodeEscape + EscapeSequence + PlainChar
+  local String = P"\"" * g.Cs (Char ^ 0) * (P"\"" + Err "unterminated string")
+  local Integer = P"-"^(-1) * (P"0" + (R"19" * R"09"^0))
+  local Fractal = P"." * R"09"^0
+  local Exponent = (S"eE") * (S"+-")^(-1) * R"09"^1
+  local Number = (Integer * Fractal^(-1) * Exponent^(-1))/str2num
+  local Constant = P"true" * g.Cc (true) + P"false" * g.Cc (false) + P"null" * g.Carg (1)
+  local SimpleValue = Number + String + Constant
+  local ArrayContent, ObjectContent
+
+  -- The functions parsearray and parseobject parse only a single value/pair
+  -- at a time and store them directly to avoid hitting the LPeg limits.
+  local function parsearray (str, pos, nullval, state)
+    local obj, cont
+    local npos
+    local t, nt = {}, 0
+    repeat
+      obj, cont, npos = pegmatch (ArrayContent, str, pos, nullval, state)
+      if not npos then break end
+      pos = npos
+      nt = nt + 1
+      t[nt] = obj
+    until cont == 'last'
+    return pos, setmetatable (t, state.arraymeta)
+  end
+
+  local function parseobject (str, pos, nullval, state)
+    local obj, key, cont
+    local npos
+    local t = {}
+    repeat
+      key, obj, cont, npos = pegmatch (ObjectContent, str, pos, nullval, state)
+      if not npos then break end
+      pos = npos
+      t[key] = obj
+    until cont == 'last'
+    return pos, setmetatable (t, state.objectmeta)
+  end
+
+  local Array = P"[" * g.Cmt (g.Carg(1) * g.Carg(2), parsearray) * Space * (P"]" + Err "']' expected")
+  local Object = P"{" * g.Cmt (g.Carg(1) * g.Carg(2), parseobject) * Space * (P"}" + Err "'}' expected")
+  local Value = Space * (Array + Object + SimpleValue)
+  local ExpectedValue = Value + Space * Err "value expected"
+  ArrayContent = Value * Space * (P"," * g.Cc'cont' + g.Cc'last') * g.Cp()
+  local Pair = g.Cg (Space * String * Space * (P":" + Err "colon expected") * ExpectedValue)
+  ObjectContent = Pair * Space * (P"," * g.Cc'cont' + g.Cc'last') * g.Cp()
+  local DecodeValue = ExpectedValue * g.Cp ()
+
+  function json.decode (str, pos, nullval, ...)
+    local state = {}
+    state.objectmeta, state.arraymeta = optionalmetatables(...)
+    local obj, retpos = pegmatch (DecodeValue, str, pos, nullval, state)
+    if state.msg then
+      return nil, state.pos, state.msg
+    else
+      return obj, retpos
+    end
+  end
+
+  -- use this function only once:
+  json.use_lpeg = function () return json end
+
+  json.using_lpeg = true
+
+  return json -- so you can get the module using json = require "dkjson".use_lpeg()
+end
+
+if always_try_using_lpeg then
+  pcall (json.use_lpeg)
+end
+
+return json
+
+-->
diff --git a/lua/json_verifier.lua b/lua/json_verifier.lua
new file mode 100644
index 0000000000000..f398f416e7b73
--- /dev/null
+++ b/lua/json_verifier.lua
@@ -0,0 +1,110 @@
+local json = require("lua/dkjson")
+local lfs = require("lfs")
+
+local exit_code = 0
+
+-- function to read a file completely into a string
+function read_file(filename)
+    local f = io.open(filename, "r")
+    local content = f:read("*all")
+    f:close()
+    return content
+end
+
+-- parse the JSON of an entire cataclysm file
+function parse_cata_json(filename, handler)
+    local content = read_file(filename)
+
+    local root, pos, err = json.decode(content, 1, nil)
+    if err then
+        print("Error in ", filename ,":", err)
+        os.exit(1)
+    else
+        -- top level should be a json array
+        if type(root) ~= "table" then
+            print("Wrong root element to JSON file ", filename, " :", type(root))
+        end
+
+        for _, entry in ipairs(root) do
+            if not entry.type then
+                print("Invalid entry type in ", filename, ": ", entry.type)
+            end
+            if handler[entry.type] then
+                handler[entry.type](entry, filename)
+            end
+        end
+    end
+end
+
+local definitions = {}
+function load_item_definition(entry, filename)
+    -- store that this item was defined
+    definitions[entry.id] = true
+end
+
+-- define load_definition handlers
+local load_definition = {}
+load_definition.BOOK        = load_item_definition
+load_definition.TOOL        = load_item_definition
+load_definition.GUN         = load_item_definition
+load_definition.GUNMOD      = load_item_definition
+load_definition.TOOL_ARMOR  = load_item_definition
+load_definition.ARMOR       = load_item_definition
+load_definition.BIONIC_ITEM = load_item_definition
+load_definition.GENERIC     = load_item_definition
+load_definition.AMMO        = load_item_definition
+load_definition.CONTAINER   = load_item_definition
+load_definition.COMESTIBLE  = load_item_definition
+
+local recipe_handler = {}
+
+function ensure_definition(id, filename, parent_id)
+    if not definitions[id] then
+        -- signify that something went wrong
+        exit_code = 1
+
+        print("Trying to access non-existent item id ", id, " in ", filename, "(", parent_id, ")")
+    end
+end
+
+recipe_handler.recipe = function(entry, filename)
+    ensure_definition(entry.result, filename, entry.result)
+    for _, alternatives in ipairs(entry.components) do
+        for _, item in ipairs(alternatives) do
+            ensure_definition(item[1], filename, entry.result)
+        end
+    end
+end
+
+function string.endswith(mystr, myend)
+   return myend=="" or string.sub(mystr,string.len(mystr)-string.len(myend)+1)==myend
+end
+
+
+function load_all_jsons_recursive(path, handler)
+    for file in lfs.dir(path) do
+        if file ~= "." and file ~= ".." then
+            local f = path..'/'..file
+
+            local attr = lfs.attributes(f)
+            if attr.mode == "directory" then
+                load_all_jsons_recursive(f, handler)
+            elseif attr.mode == "file" and string.endswith(f, ".json") then
+                parse_cata_json(f, handler)
+            end
+        end
+    end
+end
+
+function load_all_jsons(handler)
+    load_all_jsons_recursive("data/json", handler)
+    load_all_jsons_recursive("data/mods", handler)
+end
+
+-- first load all item definitions
+load_all_jsons(load_definition)
+
+-- then verify recipes
+load_all_jsons(recipe_handler)
+
+os.exit(exit_code)