libs/http/luasrc/http/protocol.lua

   1 --[[
   2
   3 HTTP protocol implementation for LuCI
   4 (c) 2008 Freifunk Leipzig / Jo-Philipp Wich <xm@leipzig.freifunk.net>
   5
   6 Licensed under the Apache License, Version 2.0 (the "License");
   7 you may not use this file except in compliance with the License.
   8 You may obtain a copy of the License at
   9
  10         http://www.apache.org/licenses/LICENSE-2.0
  11
  12 $Id$
  13
  14 ]]--
  15
  16 module("luci.http.protocol", package.seeall)
  17
  18 local ltn12 = require("luci.ltn12")
  19
  20 HTTP_MAX_CONTENT      = 1024*4          -- 4 kB maximum content size
  21 HTTP_URLENC_MAXKEYLEN = 1024            -- maximum allowd size of urlencoded parameter names
  22
  23
  24 -- Decode an urlencoded string.
  25 -- Returns the decoded value.
  26 function urldecode( str, no_plus )
  27
  28         local function __chrdec( hex )
  29                 return string.char( tonumber( hex, 16 ) )
  30         end
  31
  32         if type(str) == "string" then
  33                 if not no_plus then
  34                         str = str:gsub( "+", " " )
  35                 end
  36
  37                 str = str:gsub( "%%([a-fA-F0-9][a-fA-F0-9])", __chrdec )
  38         end
  39
  40         return str
  41 end
  42
  43
  44 -- Extract and split urlencoded data pairs, separated bei either "&" or ";" from given url.
  45 -- Returns a table value with urldecoded values.
  46 function urldecode_params( url, tbl )
  47
  48         local params = tbl or { }
  49
  50         if url:find("?") then
  51                 url = url:gsub( "^.+%?([^?]+)", "%1" )
  52         end
  53
  54         for pair in url:gmatch( "[^&;]+" ) do
  55
  56                 -- find key and value
  57                 local key = urldecode( pair:match("^([^=]+)")     )
  58                 local val = urldecode( pair:match("^[^=]+=(.+)$") )
  59
  60                 -- store
  61                 if type(key) == "string" and key:len() > 0 then
  62                         if type(val) ~= "string" then val = "" end
  63
  64                         if not params[key] then
  65                                 params[key] = val
  66                         elseif type(params[key]) ~= "table" then
  67                                 params[key] = { params[key], val }
  68                         else
  69                                 table.insert( params[key], val )
  70                         end
  71                 end
  72         end
  73
  74         return params
  75 end
  76
  77
  78 -- Encode given string in urlencoded format.
  79 -- Returns the encoded string.
  80 function urlencode( str )
  81
  82         local function __chrenc( chr )
  83                 return string.format(
  84                         "%%%02x", string.byte( chr )
  85                 )
  86         end
  87
  88         if type(str) == "string" then
  89                 str = str:gsub(
  90                         "([^a-zA-Z0-9$_%-%.%+!*'(),])",
  91                         __chrenc
  92                 )
  93         end
  94
  95         return str
  96 end
  97
  98
  99 -- Encode given table to urlencoded string.
 100 -- Returns the encoded string.
 101 function urlencode_params( tbl )
 102         local enc = ""
 103
 104         for k, v in pairs(tbl) do
 105                 enc = enc .. ( enc and "&" or "" ) ..
 106                         urlencode(k) .. "="  ..
 107                         urlencode(v)
 108         end
 109
 110         return enc
 111 end
 112
 113
 114 -- Parameter helper
 115 local function __initval( tbl, key )
 116         local multival = ( key:sub( #key - 1, #key ) == "[]" )
 117
 118         if multival then
 119                 if type(tbl[key]) == "table" then
 120                         table.insert( tbl[key], "" )
 121                 else
 122                         tbl[key] = { "" }
 123                 end
 124         else
 125                 tbl[key] = ""
 126         end
 127
 128         return multival
 129 end
 130
 131 local function __appendval( tbl, key, multival, chunk )
 132         if multival then
 133                 tbl[key][#tbl[key]] = tbl[key][#tbl[key]] .. chunk
 134         else
 135                 tbl[key] = tbl[key] .. chunk
 136         end
 137 end
 138
 139 local function __finishval( tbl, key, multival, handler )
 140         if handler then
 141                 if multival then
 142                         tbl[key][#tbl[key]] = handler( tbl[key][#tbl[key]] )
 143                 else
 144                         tbl[key] = handler( tbl[key] )
 145                 end
 146         end
 147 end
 148
 149
 150 -- Table of our process states
 151 local process_states = { }
 152
 153 -- Extract "magic", the first line of a http message.
 154 -- Extracts the message type ("get", "post" or "response"), the requested uri
 155 -- or the status code if the line descripes a http response.
 156 process_states['magic'] = function( msg, chunk, err )
 157
 158         if chunk ~= nil then
 159                 -- ignore empty lines before request
 160                 if #chunk == 0 then
 161                         return true, nil
 162                 end
 163
 164                 -- Is it a request?
 165                 local method, uri, http_ver = chunk:match("^([A-Z]+) ([^ ]+) HTTP/([01]%.[019])$")
 166
 167                 -- Yup, it is
 168                 if method then
 169
 170                         msg.type           = "request"
 171                         msg.request_method = method:lower()
 172                         msg.request_uri    = uri
 173                         msg.http_version   = tonumber( http_ver )
 174                         msg.headers        = { }
 175
 176                         -- We're done, next state is header parsing
 177                         return true, function( chunk )
 178                                 return process_states['headers']( msg, chunk )
 179                         end
 180
 181                 -- Is it a response?
 182                 else
 183
 184                         local http_ver, code, message = chunk:match("^HTTP/([01]%.[019]) ([0-9]+) ([^\r\n]+)$")
 185
 186                         -- Is a response
 187                         if code then
 188
 189                                 msg.type           = "response"
 190                                 msg.status_code    = code
 191                                 msg.status_message = message
 192                                 msg.http_version   = tonumber( http_ver )
 193                                 msg.headers        = { }
 194
 195                                 -- We're done, next state is header parsing
 196                                 return true, function( chunk )
 197                                         return process_states['headers']( msg, chunk )
 198                                 end
 199                         end
 200                 end
 201         end
 202
 203         -- Can't handle it
 204         return nil, "Invalid HTTP message magic"
 205 end
 206
 207
 208 -- Extract headers from given string.
 209 process_states['headers'] = function( msg, chunk )
 210
 211         if chunk ~= nil then
 212
 213                 -- Look for a valid header format
 214                 local hdr, val = chunk:match( "^([A-Z][A-Za-z0-9%-_]+): +(.+)$" )
 215
 216                 if type(hdr) == "string" and hdr:len() > 0 and
 217                    type(val) == "string" and val:len() > 0
 218                 then
 219                         msg.headers[hdr] = val
 220
 221                         -- Valid header line, proceed
 222                         return true, nil
 223
 224                 elseif #chunk == 0 then
 225                         -- Empty line, we won't accept data anymore
 226                         return false, nil
 227                 else
 228                         -- Junk data
 229                         return nil, "Invalid HTTP header received"
 230                 end
 231         else
 232                 return nil, "Unexpected EOF"
 233         end
 234 end
 235
 236
 237 -- Find first MIME boundary
 238 process_states['mime-init'] = function( msg, chunk, filecb )
 239
 240         if chunk ~= nil then
 241                 if #chunk >= #msg.mime_boundary + 2 then
 242                         local boundary = chunk:sub( 1, #msg.mime_boundary + 4 )
 243
 244                         if boundary == "--" .. msg.mime_boundary .. "\r\n" then
 245
 246                                 -- Store remaining data in buffer
 247                                 msg._mimebuffer = chunk:sub( #msg.mime_boundary + 5, #chunk )
 248
 249                                 -- Switch to header processing state
 250                                 return true, function( chunk )
 251                                         return process_states['mime-headers']( msg, chunk, filecb )
 252                                 end
 253                         else
 254                                 return nil, "Invalid MIME boundary"
 255                         end
 256                 else
 257                         return true
 258                 end
 259         else
 260                 return nil, "Unexpected EOF"
 261         end
 262 end
 263
 264
 265 -- Read MIME part headers
 266 process_states['mime-headers'] = function( msg, chunk, filecb )
 267
 268         if chunk ~= nil then
 269
 270                 -- Combine look-behind buffer with current chunk
 271                 chunk = msg._mimebuffer .. chunk
 272
 273                 if not msg._mimeheaders then
 274                         msg._mimeheaders = { }
 275                 end
 276
 277                 local function __storehdr( k, v )
 278                         msg._mimeheaders[k] = v
 279                         return ""
 280                 end
 281
 282                 -- Read all header lines
 283                 local ok, count = 1, 0
 284                 while ok > 0 do
 285                         chunk, ok = chunk:gsub( "^([A-Z][A-Za-z0-9%-_]+): +([^\r\n]+)\r\n", __storehdr )
 286                         count = count + ok
 287                 end
 288
 289                 -- Headers processed, check for empty line
 290                 chunk, ok = chunk:gsub( "^\r\n", "" )
 291
 292                 -- Store remaining buffer contents
 293                 msg._mimebuffer = chunk
 294
 295                 -- End of headers
 296                 if ok > 0 then
 297
 298                         -- When no Content-Type header is given assume text/plain
 299                         if not msg._mimeheaders['Content-Type'] then
 300                                 msg._mimeheaders['Content-Type'] = 'text/plain'
 301                         end
 302
 303                         -- Check Content-Disposition
 304                         if msg._mimeheaders['Content-Disposition'] then
 305                                 -- Check for "form-data" token
 306                                 if msg._mimeheaders['Content-Disposition']:match("^form%-data; ") then
 307                                         -- Check for field name, filename
 308                                         local field = msg._mimeheaders['Content-Disposition']:match('name="(.-)"')
 309                                         local file  = msg._mimeheaders['Content-Disposition']:match('filename="(.+)"$')
 310
 311                                         -- Is a file field and we have a callback
 312                                         if file and filecb then
 313                                                 msg.params[field] = file
 314                                                 msg._mimecallback = function(chunk,eof)
 315                                                         filecb( {
 316                                                                 name    = field;
 317                                                                 file    = file;
 318                                                                 headers = msg._mimeheaders
 319                                                         }, chunk, eof )
 320                                                 end
 321
 322                                         -- Treat as form field
 323                                         else
 324                                                 local mv = __initval( msg.params, field )
 325                                                 msg._mimecallback = function(chunk,eof)
 326                                                         __appendval( msg.params, field, mv, chunk )
 327                                                 end
 328                                         end
 329
 330                                         -- Header was valid, continue with mime-data
 331                                         return true, function( chunk )
 332                                                 return process_states['mime-data']( msg, chunk, filecb )
 333                                         end
 334                                 else
 335                                         -- Unknown Content-Disposition, abort
 336                                         return nil, "Unexpected Content-Disposition MIME section header"
 337                                 end
 338                         else
 339                                 -- Content-Disposition is required, abort without
 340                                 return nil, "Missing Content-Disposition MIME section header"
 341                         end
 342
 343                 -- We parsed no headers yet and buffer is almost empty
 344                 elseif count > 0 or #chunk < 128 then
 345                         -- Keep feeding me with chunks
 346                         return true, nil
 347                 end
 348
 349                 -- Buffer looks like garbage
 350                 return nil, "Malformed MIME section header"
 351         else
 352                 return nil, "Unexpected EOF"
 353         end
 354 end
 355
 356
 357 -- Read MIME part data
 358 process_states['mime-data'] = function( msg, chunk, filecb )
 359
 360         if chunk ~= nil then
 361
 362                 -- Combine look-behind buffer with current chunk
 363                 local buffer = msg._mimebuffer .. chunk
 364
 365                 -- Look for MIME boundary
 366                 local spos, epos = buffer:find( "\r\n--" .. msg.mime_boundary .. "\r\n", 1, true )
 367
 368                 if spos then
 369                         -- Content data
 370                         msg._mimecallback( buffer:sub( 1, spos - 1 ), true )
 371
 372                         -- Store remainder
 373                         msg._mimebuffer = buffer:sub( epos + 1, #buffer )
 374
 375                         -- Next state is mime-header processing
 376                         return true, function( chunk )
 377                                 return process_states['mime-headers']( msg, chunk, filecb )
 378                         end
 379                 else
 380                         -- Look for EOF?
 381                         local spos, epos = buffer:find( "\r\n--" .. msg.mime_boundary .. "--\r\n", 1, true )
 382
 383                         if spos then
 384                                 -- Content data
 385                                 msg._mimecallback( buffer:sub( 1, spos - 1 ), true )
 386
 387                                 -- We processed the final MIME boundary, cleanup
 388                                 msg._mimebuffer   = nil
 389                                 msg._mimeheaders  = nil
 390                                 msg._mimecallback = nil
 391
 392                                 -- We won't accept data anymore
 393                                 return false
 394                         else
 395                                 -- We're somewhere within a data section and our buffer is full
 396                                 if #buffer > #chunk then
 397                                         -- Flush buffered data
 398                                         msg._mimecallback( buffer:sub( 1, #buffer - #chunk ), false )
 399
 400                                         -- Store new data
 401                                         msg._mimebuffer = buffer:sub( #buffer - #chunk + 1, #buffer )
 402
 403                                 -- Buffer is not full yet, append new data
 404                                 else
 405                                         msg._mimebuffer = buffer
 406                                 end
 407
 408                                 -- Keep feeding me
 409                                 return true
 410                         end
 411                 end
 412         else
 413                 return nil, "Unexpected EOF"
 414         end
 415 end
 416
 417
 418 -- Init urldecoding stream
 419 process_states['urldecode-init'] = function( msg, chunk, filecb )
 420
 421         if chunk ~= nil then
 422
 423                 -- Check for Content-Length
 424                 if msg.env.CONTENT_LENGTH then
 425                         msg.content_length = tonumber(msg.env.CONTENT_LENGTH)
 426
 427                         if msg.content_length <= HTTP_MAX_CONTENT then
 428                                 -- Initialize buffer
 429                                 msg._urldecbuffer = chunk
 430                                 msg._urldeclength = 0
 431
 432                                 -- Switch to urldecode-key state
 433                                 return true, function(chunk)
 434                                         return process_states['urldecode-key']( msg, chunk, filecb )
 435                                 end
 436                         else
 437                                 return nil, "Request exceeds maximum allowed size"
 438                         end
 439                 else
 440                         return nil, "Missing Content-Length header"
 441                 end
 442         else
 443                 return nil, "Unexpected EOF"
 444         end
 445 end
 446
 447
 448 -- Process urldecoding stream, read and validate parameter key
 449 process_states['urldecode-key'] = function( msg, chunk, filecb )
 450         if chunk ~= nil then
 451
 452                 -- Prevent oversized requests
 453                 if msg._urldeclength >= msg.content_length then
 454                         return nil, "Request exceeds maximum allowed size"
 455                 end
 456
 457                 -- Combine look-behind buffer with current chunk
 458                 local buffer = msg._urldecbuffer .. chunk
 459                 local spos, epos = buffer:find("=")
 460
 461                 -- Found param
 462                 if spos then
 463
 464                         -- Check that key doesn't exceed maximum allowed key length
 465                         if ( spos - 1 ) <= HTTP_URLENC_MAXKEYLEN then
 466                                 local key = urldecode( buffer:sub( 1, spos - 1 ) )
 467
 468                                 -- Prepare buffers
 469                                 msg.params[key]         = ""
 470                                 msg._urldeclength   = msg._urldeclength + epos
 471                                 msg._urldecbuffer   = buffer:sub( epos + 1, #buffer )
 472
 473                                 -- Use file callback or store values inside msg.params
 474                                 if filecb then
 475                                         msg._urldeccallback = function( chunk, eof )
 476                                                 filecb( field, chunk, eof )
 477                                         end
 478                                 else
 479                                         local mv = __initval( msg.params, key )
 480                                         msg._urldeccallback = function( chunk, eof )
 481                                                 __appendval( msg.params, key, mv, chunk )
 482
 483                                                 -- FIXME: Use a filter
 484                                                 if eof then
 485                                                         __finishval( msg.params, key, mv, urldecode )
 486                                                 end
 487                                         end
 488                                 end
 489
 490                                 -- Proceed with urldecode-value state
 491                                 return true, function( chunk )
 492                                         return process_states['urldecode-value']( msg, chunk, filecb )
 493                                 end
 494                         else
 495                                 return nil, "POST parameter exceeds maximum allowed length"
 496                         end
 497                 else
 498                         return nil, "POST data exceeds maximum allowed length"
 499                 end
 500         else
 501                 return nil, "Unexpected EOF"
 502         end
 503 end
 504
 505
 506 -- Process urldecoding stream, read parameter value
 507 process_states['urldecode-value'] = function( msg, chunk, filecb )
 508
 509         if chunk ~= nil then
 510
 511                 -- Combine look-behind buffer with current chunk
 512                 local buffer = msg._urldecbuffer .. chunk
 513
 514                 -- Check for EOF
 515                 if #buffer == 0 then
 516                         -- Compare processed length
 517                         if msg._urldeclength == msg.content_length then
 518                                 -- Cleanup
 519                                 msg._urldeclength   = nil
 520                                 msg._urldecbuffer   = nil
 521                                 msg._urldeccallback = nil
 522
 523                                 -- We won't accept data anymore
 524                                 return false
 525                         else
 526                                 return nil, "Content-Length mismatch"
 527                         end
 528                 end
 529
 530                 -- Check for end of value
 531                 local spos, epos = buffer:find("[&;]")
 532                 if spos then
 533
 534                         -- Flush buffer, send eof
 535                         msg._urldeccallback( buffer:sub( 1, spos - 1 ), true )
 536                         msg._urldecbuffer = buffer:sub( epos + 1, #buffer )
 537                         msg._urldeclength = msg._urldeclength + epos
 538
 539                         -- Back to urldecode-key state
 540                         return true, function( chunk )
 541                                 return process_states['urldecode-key']( msg, chunk, filecb )
 542                         end
 543                 else
 544                         -- We're somewhere within a data section and our buffer is full
 545                         if #buffer > #chunk then
 546                                 -- Flush buffered data
 547                                 msg._urldeccallback( buffer:sub( 1, #buffer - #chunk ), false )
 548
 549                                 -- Store new data
 550                                 msg._urldeclength = msg._urldeclength + #buffer - #chunk
 551                                 msg._urldecbuffer = buffer:sub( #buffer - #chunk + 1, #buffer )
 552
 553                         -- Buffer is not full yet, append new data
 554                         else
 555                                 msg._urldecbuffer = buffer
 556                         end
 557
 558                         -- Keep feeding me
 559                         return true
 560                 end
 561         else
 562                 -- Send EOF
 563                 msg._urldeccallback( "", true )
 564                 return false
 565         end
 566 end
 567
 568
 569 -- Creates a header source from a given socket
 570 function header_source( sock )
 571         return ltn12.source.simplify( function()
 572
 573                 local chunk, err, part = sock:receive("*l")
 574
 575                 -- Line too long
 576                 if chunk == nil then
 577                         if err ~= "timeout" then
 578                                 return nil, part
 579                                         and "Line exceeds maximum allowed length"
 580                                         or  "Unexpected EOF"
 581                         else
 582                                 return nil, err
 583                         end
 584
 585                 -- Line ok
 586                 elseif chunk ~= nil then
 587
 588                         -- Strip trailing CR
 589                         chunk = chunk:gsub("\r$","")
 590
 591                         return chunk, nil
 592                 end
 593         end )
 594 end
 595
 596
 597 -- Decode MIME encoded data.
 598 function mimedecode_message_body( source, msg, filecb )
 599
 600         -- Find mime boundary
 601         if msg and msg.env.CONTENT_TYPE then
 602
 603                 local bound = msg.env.CONTENT_TYPE:match("^multipart/form%-data; boundary=(.+)")
 604
 605                 if bound then
 606                         msg.mime_boundary = bound
 607                 else
 608                         return nil, "No MIME boundary found or invalid content type given"
 609                 end
 610         end
 611
 612         -- Create an initial LTN12 sink
 613         -- The whole MIME parsing process is implemented as fancy sink, sinks replace themself
 614         -- depending on current processing state (init, header, data). Return the initial state.
 615         local sink = ltn12.sink.simplify(
 616                 function( chunk )
 617                         return process_states['mime-init']( msg, chunk, filecb )
 618                 end
 619         )
 620
 621         -- Create a throttling LTN12 source
 622         -- Frequent state switching in the mime parsing process leads to unwanted buffer aggregation.
 623         -- This source checks wheather there's still data in our internal read buffer and returns an
 624         -- empty string if there's already enough data in the processing queue. If the internal buffer
 625         -- runs empty we're calling the original source to get the next chunk of data.
 626         local tsrc = function()
 627
 628                 -- XXX: we schould propably keep the maximum buffer size in sync with
 629                 --      the blocksize of our original source... but doesn't really matter
 630                 if msg._mimebuffer ~= null and #msg._mimebuffer > 256 then
 631                         return ""
 632                 else
 633                         return source()
 634                 end
 635         end
 636
 637         -- Pump input data...
 638         while true do
 639                 -- get data
 640                 local ok, err = ltn12.pump.step( tsrc, sink )
 641
 642                 -- error
 643                 if not ok and err then
 644                         return nil, err
 645
 646                 -- eof
 647                 elseif not ok then
 648                         return true
 649                 end
 650         end
 651 end
 652
 653
 654 -- Decode urlencoded data.
 655 function urldecode_message_body( source, msg )
 656
 657         -- Create an initial LTN12 sink
 658         -- Return the initial state.
 659         local sink = ltn12.sink.simplify(
 660                 function( chunk )
 661                         return process_states['urldecode-init']( msg, chunk )
 662                 end
 663         )
 664
 665         -- Create a throttling LTN12 source
 666         -- See explaination in mimedecode_message_body().
 667         local tsrc = function()
 668                 if msg._urldecbuffer ~= null and #msg._urldecbuffer > 0 then
 669                         return ""
 670                 else
 671                         return source()
 672                 end
 673         end
 674
 675         -- Pump input data...
 676         while true do
 677                 -- get data
 678                 local ok, err = ltn12.pump.step( tsrc, sink )
 679
 680                 -- step
 681                 if not ok and err then
 682                         return nil, err
 683
 684                 -- eof
 685                 elseif not ok then
 686                         return true
 687                 end
 688         end
 689 end
 690
 691
 692 -- Parse a http message header
 693 function parse_message_header( source )
 694
 695         local ok   = true
 696         local msg  = { }
 697
 698         local sink = ltn12.sink.simplify(
 699                 function( chunk )
 700                         return process_states['magic']( msg, chunk )
 701                 end
 702         )
 703
 704         -- Pump input data...
 705         while ok do
 706
 707                 -- get data
 708                 ok, err = ltn12.pump.step( source, sink )
 709
 710                 -- error
 711                 if not ok and err then
 712                         return nil, err
 713
 714                 -- eof
 715                 elseif not ok then
 716
 717                         -- Process get parameters
 718                         if ( msg.request_method == "get" or msg.request_method == "post" ) and
 719                            msg.request_uri:match("?")
 720                         then
 721                                 msg.params = urldecode_params( msg.request_uri )
 722                         else
 723                                 msg.params = { }
 724                         end
 725
 726                         -- Populate common environment variables
 727                         msg.env = {
 728                                 CONTENT_LENGTH    = msg.headers['Content-Length'];
 729                                 CONTENT_TYPE      = msg.headers['Content-Type'];
 730                                 REQUEST_METHOD    = msg.request_method:upper();
 731                                 REQUEST_URI       = msg.request_uri;
 732                                 SCRIPT_NAME       = msg.request_uri:gsub("?.+$","");
 733                                 SCRIPT_FILENAME   = "";         -- XXX implement me
 734                                 SERVER_PROTOCOL   = "HTTP/" .. string.format("%.1f", msg.http_version)
 735                         }
 736
 737                         -- Populate HTTP_* environment variables
 738                         for i, hdr in ipairs( {
 739                                 'Accept',
 740                                 'Accept-Charset',
 741                                 'Accept-Encoding',
 742                                 'Accept-Language',
 743                                 'Connection',
 744                                 'Cookie',
 745                                 'Host',
 746                                 'Referer',
 747                                 'User-Agent',
 748                         } ) do
 749                                 local var = 'HTTP_' .. hdr:upper():gsub("%-","_")
 750                                 local val = msg.headers[hdr]
 751
 752                                 msg.env[var] = val
 753                         end
 754                 end
 755         end
 756
 757         return msg
 758 end
 759
 760
 761 -- Parse a http message body
 762 function parse_message_body( source, msg, filecb )
 763         -- Is it multipart/mime ?
 764         if msg.env.REQUEST_METHOD == "POST" and msg.env.CONTENT_TYPE and
 765            msg.env.CONTENT_TYPE:match("^multipart/form%-data")
 766         then
 767
 768                 return mimedecode_message_body( source, msg, filecb )
 769
 770         -- Is it application/x-www-form-urlencoded ?
 771         elseif msg.env.REQUEST_METHOD == "POST" and msg.env.CONTENT_TYPE and
 772                msg.env.CONTENT_TYPE == "application/x-www-form-urlencoded"
 773         then
 774                 return urldecode_message_body( source, msg, filecb )
 775
 776
 777         -- Unhandled encoding
 778         -- If a file callback is given then feed it chunk by chunk, else
 779         -- store whole buffer in message.content
 780         else
 781
 782                 local sink
 783
 784                 -- If we have a file callback then feed it
 785                 if type(filecb) == "function" then
 786                         sink = filecb
 787
 788                 -- ... else append to .content
 789                 else
 790                         msg.content = ""
 791                         msg.content_length = 0
 792
 793                         sink = function( chunk )
 794                                 if ( msg.content_length + #chunk ) <= HTTP_MAX_CONTENT then
 795
 796                                         msg.content        = msg.content        .. chunk
 797                                         msg.content_length = msg.content_length + #chunk
 798
 799                                         return true
 800                                 else
 801                                         return nil, "POST data exceeds maximum allowed length"
 802                                 end
 803                         end
 804                 end
 805
 806                 -- Pump data...
 807                 while true do
 808                         local ok, err = ltn12.pump.step( source, sink )
 809
 810                         if not ok and err then
 811                                 return nil, err
 812                         elseif not err then
 813                                 return true
 814                         end
 815                 end
 816         end
 817 end
 818
 819 -- Status codes
 820 statusmsg = {
 821         [200] = "OK",
 822         [301] = "Moved Permanently",
 823         [304] = "Not Modified",
 824         [400] = "Bad Request",
 825         [403] = "Forbidden",
 826         [404] = "Not Found",
 827         [405] = "Method Not Allowed",
 828         [411] = "Length Required",
 829         [412] = "Precondition Failed",
 830         [500] = "Internal Server Error",
 831         [503] = "Server Unavailable",
 832 }