--- -- Library methods for handling JSON data. It handles JSON encoding and -- decoding according to RFC 4627. -- -- There is a test section at the bottom which shows some example -- parsing. If you want to parse JSON, you can test it by pasting sample JSON -- into the TESTS table and run the test method -- -- There is a straightforward mapping between JSON and Lua data types. One -- exception is JSON NULL, which is not the same as Lua -- nil. (A better match for Lua nil is JavaScript -- undefined.) NULL values in JSON are represented by -- the special value json.NULL. -- -- @author Martin Holst Swende -- @copyright Same as Nmap--See http://nmap.org/book/man-legal.html -- TODO: Unescape/escape unicode -- Version 0.4 -- Created 01/25/2010 - v0.1 - created by Martin Holst Swende -- Heavily modified 02/22/2010 - v0.3. Rewrote the parser into an OO-form, to not have to handle -- all kinds of state with parameters and return values. -- Modified 02/27/2010 - v0.4 Added unicode handling (written by David Fifield). Renamed toJson -- and fromJson intogenerate() and parse(), implemented more proper numeric parsing and added some more error checking. module("json", package.seeall) require("bit") require("nsedebug") --Some local shortcuts local function dbg(str,...) stdnse.print_debug("Json:"..str, unpack(arg)) end local function d4(str,...) if nmap.debugging() > 3 then dbg(str,unpack(arg)) end end local function d3(str,...) if nmap.debugging() > 2 then dbg(str,unpack(arg)) end end --local dbg =stdnse.print_debug local function dbg_err(str,...) stdnse.print_debug("json-ERR:"..str, unpack(arg)) end -- Javascript null representation, see explanation above NULL = {} -- See section 2.5 for escapes. -- For convenience, ESCAPE_TABLE maps to escape sequences complete with -- backslash, and REVERSE_ESCAPE_TABLE maps from single escape characters -- (no backslash). local ESCAPE_TABLE = {} local REVERSE_ESCAPE_TABLE = {} do local escapes = { [string.char(0x22)] = "\"", [string.char(0x5C)] = "\\", [string.char(0x2F)] = "/", [string.char(0x08)] = "b", [string.char(0x0C)] = "f", [string.char(0x0A)] = "n", [string.char(0x0D)] = "r", [string.char(0x09)] = "t", } for k, v in pairs(escapes) do ESCAPE_TABLE[k] = "\\" .. v REVERSE_ESCAPE_TABLE[v] = k end end -- Escapes a string --@param str the string --@return a string where the special chars have been escaped local function escape(str) return "\"" .. string.gsub(str, ".", ESCAPE_TABLE) .. "\"" end -- Creates json data from an object --@param object a table containing data --@return a string containing valid json function generate(obj) -- NULL-check must be performed before -- checking type == table, since the NULL-object -- is a table if obj == NULL then return "null" elseif obj == false then return "false" elseif obj == true then return "true" elseif type(obj) == "number" then return string.format("%g", obj) elseif type(obj) == "string" then return escape(obj) elseif type(obj) == "table" then local k, v, elems elems = {} if #obj > 0 then -- Array for _, v in ipairs(obj) do elems[#elems + 1] = generate(v) end return "[" .. table.concat(elems, ", ") .. "]" else -- Object for k, v in pairs(obj) do elems[#elems + 1] = escape(k) .. ": " .. generate(v) end return "{" .. table.concat(elems, ", ") .. "}" end else error("Unknown data type in generate") end end -- This is the parser, implemented in OO-form to deal with state better Json = {} -- Constructor function Json:new(input) local o = {} setmetatable(o, self) self.__index = self o.input = input o.pos = 1 -- Pos is where the NEXT letter will be read return o end -- Gets next character and ups the position --@return next character function Json:next() self.pos = self.pos+1 return self.input:sub(self.pos-1, self.pos-1) end -- Updates the position to next non whitespace position function Json:eatWhiteSpace() --Find next non-white char local a,b = self.input:find("%S",self.pos) if not a then self:syntaxerror("Empty data") return end self.pos = a end -- Jumps to a specified position --@param position where to go function Json:jumpTo(position) self.pos = position end -- Returns next character, but without upping position --@return next character function Json:peek() return self.input:sub(self.pos, self.pos) end --@return true if more input is in store function Json:hasMore() return self.input:len() >= self.pos end -- Checks that the following input is equal to a string -- and updates position so next char will be after that string -- If false, triggers a syntax error --@param str the string to test function Json:assertStr(str) local content = self.input:sub(self.pos,self.pos+str:len()-1) if(content == str) then-- All ok -- Jump forward self:jumpTo(self.pos+str:len()) return end self:syntaxerror(("Expected '%s' but got '%s'"):format( str, content)) end -- Trigger a syntax error function Json:syntaxerror(reason) self.error = ("Syntax error near pos %d: %s input: %s"):format( self.pos, reason, self.input) dbg(self.error) end -- Check if any errors has occurred function Json:errors() return self.error ~= nil end -- Parses a top-level JSON structure (object or array). --@return the parsed object or puts error messages in self.error function Json:parseStart() -- The top level of JSON only allows an object or an array. Only inside -- of the outermost container can other types appear. self:eatWhiteSpace() local c = self:peek() if c == '{' then return self:parseObject() elseif c == '[' then return self:parseArray() else self:syntaxerror(("JSON must start with object or array (started with %s)"):format(c)) return end end -- Parses a value --@return the parsed value function Json:parseValue() self:eatWhiteSpace() local c = self:peek() local value if c == '{' then value = self:parseObject() elseif c == '[' then value = self:parseArray() elseif c == '"' then value = self:parseString() elseif c == 'n' then self:assertStr("null") value = NULL elseif c == 't' then self:assertStr("true") value = true elseif c == 'f' then self:assertStr("false") value = false else -- numeric -- number = [ minus ] int [ frac ] [ exp ] local a,b =self.input:find("-?%d+%.?%d*[eE]?[+-]?%d*", self.pos) if not a or not b then self:syntaxerror("Error 1 parsing numeric value") return end value = tonumber(self.input:sub(a,b)) if(value == nil) then self:syntaxerror("Error 2 parsing numeric value") return end self:jumpTo(b+1) end return value end -- Parses a json object {} --@return the object (or triggers a syntax error) function Json:parseObject() local object = {} local _= self:next() -- Eat { while(self:hasMore() and not self:errors()) do self:eatWhiteSpace() local c = self:peek() if(c == '}') then -- Empty object, probably self:next() -- Eat it return object end if(c ~= '"') then self:syntaxerror(("Expected '\"', got '%s'"):format(c)) return end local key = self:parseString() if self:errors() then return end self:eatWhiteSpace() c = self:next() if(c ~= ':') then self:syntaxerror("Expected ':' got "..c) return end local value = self:parseValue() if self:errors() then return end object[key] = value self:eatWhiteSpace() c = self:next() -- Valid now is , or } if(c == '}') then return object end if(c ~= ',') then self:syntaxerror("Expected ',' or '}', got "..c) return end end end -- Parses a json array [] or triggers a syntax error --@return the array object function Json:parseArray() local array = {} self:next() while(self:hasMore() and not self:errors()) do self:eatWhiteSpace() if(self:peek() == ']') then -- Empty array, probably self:next() break end local value = self:parseValue() if self:errors() then return end table.insert(array, value) self:eatWhiteSpace() local c = self:next() -- Valid now is , or ] if(c == ']') then return array end if(c ~= ',') then self:syntaxerror(("Expected ',' but got '%s'"):format(c)) return end end return array end -- Decode a Unicode escape, assuming that self.pos starts just after the -- initial \u. May consume an additional escape in the case of a UTF-16 -- surrogate pair. See RFC 2781 for UTF-16. function Json:parseUnicodeEscape() local n, cp local hex, lowhex local s, e s, e, hex = self.input:find("^(....)", self.pos) if not hex then self:syntaxerror(("EOF in Unicode escape \\u%s"):format(self.input:sub(self.pos))) return end n = tonumber(hex, 16) if not n then self:syntaxerror(("Bad unicode escape \\u%s"):format(hex)) return end cp = n self.pos = e + 1 if n < 0xD800 or n > 0xDFFF then return cp end if n >= 0xDC00 and n <= 0xDFFF then self:syntaxerror(("Not a Unicode character: U+%04X"):format(cp)) return end -- Beginning of a UTF-16 surrogate. s, e, lowhex = self.input:find("^\\u(....)", self.pos) if not lowhex then self:syntaxerror(("Bad unicode escape \\u%s (missing low surrogate)"):format(hex)) return end n = tonumber(lowhex, 16) if not n or not (n >= 0xDC00 and n <= 0xDFFF) then self:syntaxerror(("Bad unicode escape \\u%s\\u%s (bad low surrogate)"):format(hex, lowhex)) return end self.pos = e + 1 cp = 0x10000 + bit.band(cp, 0x3FF) * 0x400 + bit.band(n, 0x3FF) -- also remove last " return cp end -- Encode a Unicode code point to UTF-8. See RFC 3629. -- Does not check that cp is a real charaacter; that is, doesn't exclude the -- surrogate range U+D800 - U+DFFF and a handful of others. local function utf8_enc(cp) local bytes = {} local n, mask if cp % 1.0 ~= 0.0 or cp < 0 then -- Only defined for nonnegative integers. return nil elseif cp <= 0x7F then -- Special case of one-byte encoding. return string.char(cp) elseif cp <= 0x7FF then n = 2 mask = 0xC0 elseif cp <= 0xFFFF then n = 3 mask = 0xE0 elseif cp <= 0x10FFFF then n = 4 mask = 0xF0 else return nil end while n > 1 do bytes[n] = string.char(0x80 + bit.band(cp, 0x3F)) cp = bit.rshift(cp, 6) n = n - 1 end bytes[1] = string.char(mask + cp) return table.concat(bytes) end -- Parses a json string -- @return the string or triggers syntax error function Json:parseString() local val = '' local c = self:next() assert( c == '"') while(self:hasMore()) do local c = self:next() if(c == '"') then -- end of string break elseif(c == '\\') then-- Escaped char local d = self:next() if REVERSE_ESCAPE_TABLE[d] ~= nil then val = val .. REVERSE_ESCAPE_TABLE[d] elseif d == 'u' then -- Unicode chars local codepoint = self:parseUnicodeEscape() if not codepoint then return end val = val .. utf8_enc(codepoint) else self:syntaxerror(("Undefined escape character '%s'"):format(d)) return false end else -- Char val = val .. c end end return val end --- Parses json data into an object form -- This is the method you probably want to use if you -- use this library from a script. --@param data a json string --@return status true if ok, false if bad --@return an object representing the json, or error message function parse(data) local parser = Json:new(data) local result = parser:parseStart() if(parser.error) then return false, parser.error end return true, result end ---------------------------------------------------------------------------------- -- Test-code for debugging purposes below ---------------------------------------------------------------------------------- local TESTS = { '{"a":1}', '{"a":true}', '{"a": false}', '{"a": null \r\n, \t "b" \f:"ehlo"}', '{"a\\"a":"a\\"b\\"c\\"d"}', '{"foo":"gaz\\"onk", "pi":3.14159,"hello":{ "wo":"rld"}}', '{"a":1, "b":2}', '{"foo":"gazonk", "pi":3.14159,"hello":{ "wo":"rl\\td"}}', '[1,2,3,4,5,null,false,true,"\195\164\195\165\195\182\195\177","bar"]', '[]',-- This will yield {} in toJson, since in lua there is only one basic datatype - and no difference when empty '{}', '', -- error 'null', -- error '"abc"', -- error '{a":1}', -- error '{"a" bad :1}', -- error '["a\\\\t"]', -- Should become Lua {"a\\t"} '[0.0.0]', -- error '[-1]', '[-1.123e-2]', '[5e3]', '[5e+3]', '[5E-3]', '[5.5e3]', '["a\\\\"]', -- Should become Lua {"a\\"} '{"a}": 1}', -- Should become Lua {"a}" = 1} '["key": "value"]', -- error '["\\u0041"]', -- Should become Lua {"A"} '["\\uD800"]', -- error '["\\uD834\\uDD1EX"]', -- Should become Lua {"\240\157\132\158X"} } function test() print("Tests running") local i,v,res,status for i,v in pairs(TESTS) do print("----------------------------") print(v) status,res = parse(v) if not status then print( res) end if(status) then print(generate(res)) else print("Error:".. res) end end end