mod_json_streams/mod_json_streams.lua

   1 --
   2 -- XEP-0295: JSON Encodings for XMPP
   3 --
   4
   5 module.host = "*"
   6
   7 local httpserver = require "net.httpserver";
   8 local filters = require "util.filters"
   9 local json = require "util.json"
  10
  11 local json_escapes = {
  12         ["\""] = "\\\"", ["\\"] = "\\\\", ["\b"] = "\\b", ["\f"] = "\\f",
  13         ["\n"] = "\\n", ["\r"] = "\\r", ["\t"] = "\\t"};
  14
  15 local s_char = string.char;
  16 for i=0,31 do
  17         local ch = s_char(i);
  18         if not json_escapes[ch] then json_escapes[ch] = ("\\u%.4X"):format(i); end
  19 end
  20
  21 local state_out = 0;
  22 local state_key_before = 1;
  23 local state_key_in = 2;
  24 local state_key_escape = 3;
  25 local state_key_after = 4;
  26 local state_val_before = 5;
  27 local state_val_in = 6;
  28 local state_val_escape = 7;
  29 local state_val_after = 8;
  30
  31 local whitespace = { [" "] = true, ["\n"] = true, ["\r"] = true, ["\t"] = true };
  32 function json_decoder()
  33         local state = state_out;
  34         local quote;
  35         local output = "";
  36         local buffer = "";
  37         return function(input)
  38                 for ch in input:gmatch(".") do
  39                         module:log("debug", "%s | %d", ch, state)
  40                         local final = false;
  41                         if state == state_out then
  42                                 if whitespace[ch] then
  43                                 elseif ch ~= "{" then return nil, "{ expected";
  44                                 else state = state_key_before end
  45                         elseif state == state_key_before then
  46                                 if whitespace[ch] then
  47                                 elseif ch ~= "'" and ch ~= "\"" then return nil, "\" expected";
  48                                 else quote = ch; state = state_key_in; end
  49                         elseif state == state_key_in then
  50                                 if ch == quote then state = state_key_after;
  51                                 elseif ch ~= "s" then return nil, "invalid key, 's' expected"; -- only s as key allowed
  52                                 else end -- ignore key
  53                         elseif state == state_key_after then
  54                                 if whitespace[ch] then
  55                                 elseif ch ~= ":" then return nil, ": expected";
  56                                 else state = state_val_before; end
  57                         elseif state == state_val_before then
  58                                 if whitespace[ch] then
  59                                 elseif ch ~= "'" and ch ~= "\"" then return nil, "\" expected";
  60                                 else quote = ch; state = state_val_in; end
  61                         elseif state == state_val_in then
  62                                 if ch == quote then state = state_val_after;
  63                                 elseif ch == "\\" then state = state_val_escape;
  64                                 else end
  65                         elseif state == state_val_after then
  66                                 if whitespace[ch] then
  67                                 elseif ch ~= "}" then return nil, "} expected";
  68                                 else state = state_out;
  69                                         final = true;
  70                                 end
  71                         elseif state == state_val_escape then
  72                                 state = state_val_in;
  73                         else
  74                                 module:log("error", "Unhandled state: "..state);
  75                                 return nil, "Unhandled state in parser"
  76                         end
  77                         buffer = buffer..ch;
  78                         if final then
  79                                 module:log("debug", "%s", buffer)
  80                                 local tmp;
  81                                 pcall(function() tmp = json.decode(buffer); end);
  82                                 if not tmp then return nil, "Invalid JSON"; end
  83                                 output, buffer = output..tmp.s, "";
  84                         end
  85                 end
  86                 local _ = output; output = "";
  87                 return _;
  88         end;
  89 end
  90
  91 function filter_hook(session)
  92         local determined = false;
  93         local is_json = false;
  94         local function in_filter(t)
  95                 if not determined then
  96                         is_json = (t:sub(1,1) == "{") and json_decoder();
  97                         determined = true;
  98                 end
  99                 if is_json then
 100                         local s, err = is_json(t);
 101                         if not err then return s; end
 102                         session:close("not-well-formed");
 103                         return;
 104                 end
 105                 return t;
 106         end
 107         local function out_filter(t)
 108                 if is_json then
 109                         return '{"s":"' .. t:gsub(".", json_escapes) .. '"}'; -- encode
 110                 end
 111                 return t;
 112         end
 113         filters.add_filter(session, "bytes/in", in_filter,   100);
 114         filters.add_filter(session, "bytes/out", out_filter, 100);
 115 end
 116
 117 function module.load()
 118         filters.add_filter_hook(filter_hook);
 119 end
 120 function module.unload()
 121         filters.remove_filter_hook(filter_hook);
 122 end
 123
 124 function encode(data)
 125         if type(data) == "string" then
 126                 data = json.encode({ s = data });
 127         elseif type(data) == "table" and data.body then
 128                 data.body = json.encode({ s = data.body });
 129                 data.headers["Content-Type"] = "application/json";
 130         end
 131         return data;
 132 end
 133 function handle_request(method, body, request)
 134         local mod_bosh = modulemanager.get_module("*", "bosh")
 135         if mod_bosh then
 136                 if body and method == "POST" then
 137                         pcall(function() body = json.decode(body).s; end);
 138                 end
 139                 local _send = request.send;
 140                 function request:send(data) return _send(self, encode(data)); end
 141                 return encode(mod_bosh.handle_request(method, body, request));
 142         end
 143         return "<html><body>mod_bosh not loaded</body></html>";
 144 end
 145
 146 local function setup()
 147         local ports = module:get_option("jsonstreams_ports") or { 5280 };
 148         httpserver.new_from_config(ports, handle_request, { base = "jsonstreams" });
 149 end
 150 if prosody.start_time then -- already started
 151         setup();
 152 else
 153         prosody.events.add_handler("server-started", setup);
 154 end