lib/bennu/iCalendar_rfc2445.php

   1 <?php
   2
   3 /**
   4  *  BENNU - PHP iCalendar library
   5  *  (c) 2005-2006 Ioannis Papaioannou (pj@moodle.org). All rights reserved.
   6  *
   7  *  Released under the LGPL.
   8  *
   9  *  See http://bennu.sourceforge.net/ for more information and downloads.
  10  *
  11  * @author Ioannis Papaioannou
  12  * @license http://www.gnu.org/copyleft/lesser.html GNU Lesser General Public License
  13  */
  14
  15 /*
  16
  17    All names of properties, property parameters, enumerated property
  18    values and property parameter values are case-insensitive. However,
  19    all other property values are case-sensitive, unless otherwise
  20    stated.
  21
  22 */
  23
  24 define('RFC2445_CRLF',               "\r\n");
  25 define('RFC2445_WSP',                "\t ");
  26 define('RFC2445_WEEKDAYS',           'MO,TU,WE,TH,FR,SA,SU');
  27 define('RFC2445_FOLDED_LINE_LENGTH', 75);
  28
  29 define('RFC2445_PARAMETER_SEPARATOR',   ';');
  30 define('RFC2445_VALUE_SEPARATOR',       ':');
  31
  32 define('RFC2445_REQUIRED', 0x01);
  33 define('RFC2445_OPTIONAL', 0x02);
  34 define('RFC2445_ONCE',     0x04);
  35
  36 define('RFC2445_PROP_FLAGS',       0);
  37 define('RFC2445_PROP_TYPE',        1);
  38 define('RFC2445_PROP_DEFAULT',     2);
  39
  40 define('RFC2445_XNAME', 'X-');
  41
  42 define('RFC2445_TYPE_BINARY',       0);
  43 define('RFC2445_TYPE_BOOLEAN',      1);
  44 define('RFC2445_TYPE_CAL_ADDRESS',  2);
  45 define('RFC2445_TYPE_DATE',         3);
  46 define('RFC2445_TYPE_DATE_TIME',    4);
  47 define('RFC2445_TYPE_DURATION',     5);
  48 define('RFC2445_TYPE_FLOAT',        6);
  49 define('RFC2445_TYPE_INTEGER',      7);
  50 define('RFC2445_TYPE_PERIOD',       8);
  51 define('RFC2445_TYPE_RECUR',        9);
  52 define('RFC2445_TYPE_TEXT',        10);
  53 define('RFC2445_TYPE_TIME',        11);
  54 define('RFC2445_TYPE_URI',         12); // CAL_ADDRESS === URI
  55 define('RFC2445_TYPE_UTC_OFFSET',  13);
  56
  57
  58 function rfc2445_fold($string) {
  59     if(core_text::strlen($string, 'utf-8') <= RFC2445_FOLDED_LINE_LENGTH) {
  60         return $string;
  61     }
  62
  63     $retval = '';
  64
  65     $i=0;
  66     $len_count=0;
  67
  68     //multi-byte string, get the correct length
  69     $section_len = core_text::strlen($string, 'utf-8');
  70
  71     while($len_count<$section_len) {
  72
  73         //get the current portion of the line
  74         $section = core_text::substr($string, ($i * RFC2445_FOLDED_LINE_LENGTH), (RFC2445_FOLDED_LINE_LENGTH), 'utf-8');
  75
  76         //increment the length we've processed by the length of the new portion
  77         $len_count += core_text::strlen($section, 'utf-8');
  78
  79         /* Add the portion to the return value, terminating with CRLF.HTAB
  80            As per RFC 2445, CRLF.HTAB will be replaced by the processor of the
  81            data */
  82         $retval .= $section . RFC2445_CRLF . substr(RFC2445_WSP, 0, 1);
  83
  84         $i++;
  85     }
  86
  87     return $retval;
  88
  89 }
  90
  91 function rfc2445_unfold($string) {
  92     for($i = 0; $i < strlen(RFC2445_WSP); ++$i) {
  93         $string = str_replace(RFC2445_CRLF.substr(RFC2445_WSP, $i, 1), '', $string);
  94     }
  95
  96     return $string;
  97 }
  98
  99 function rfc2445_is_xname($name) {
 100
 101     // If it's less than 3 chars, it cannot be legal
 102     if(strlen($name) < 3) {
 103         return false;
 104     }
 105
 106     // If it contains an illegal char anywhere, reject it
 107     if(strspn($name, 'ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789-') != strlen($name)) {
 108         return false;
 109     }
 110
 111     // To be legal, it must still start with "X-"
 112     return substr($name, 0, 2) === 'X-';
 113 }
 114
 115 function rfc2445_is_valid_value($value, $type) {
 116
 117     // This branch should only be taken with xname values
 118     if($type === NULL) {
 119         return true;
 120     }
 121
 122     switch($type) {
 123         case RFC2445_TYPE_CAL_ADDRESS:
 124         case RFC2445_TYPE_URI:
 125             if(!is_string($value)) {
 126                 return false;
 127             }
 128
 129             $valid_schemes = array('ftp', 'http', 'ldap', 'gopher', 'mailto', 'news', 'nntp', 'telnet', 'wais', 'file', 'prospero');
 130
 131             $pos = strpos($value, ':');
 132             if(!$pos) {
 133                 return false;
 134             }
 135
 136             $scheme = strtolower(substr($value, 0, $pos));
 137             $remain = substr($value, $pos + 1);
 138
 139             if(!in_array($scheme, $valid_schemes)) {
 140                 return false;
 141             }
 142
 143             if($scheme === 'mailto') {
 144                 $regexp = '#^[a-zA-Z0-9]+[_a-zA-Z0-9\-]*(\.[_a-z0-9\-]+)*@(([0-9a-zA-Z\-]+\.)+[a-zA-Z][0-9a-zA-Z\-]+|([0-9]{1,3}\.){3}[0-9]{1,3})$#';
 145             }
 146             else {
 147                 $regexp = '#^//(.+(:.*)?@)?(([0-9a-zA-Z\-]+\.)+[a-zA-Z][0-9a-zA-Z\-]+|([0-9]{1,3}\.){3}[0-9]{1,3})(:[0-9]{1,5})?(/.*)?$#';
 148             }
 149
 150             return preg_match($regexp, $remain);
 151         break;
 152
 153         case RFC2445_TYPE_BINARY:
 154             if(!is_string($value)) {
 155                 return false;
 156             }
 157
 158             $len = strlen($value);
 159
 160             if($len % 4 != 0) {
 161                 return false;
 162             }
 163
 164             for($i = 0; $i < $len; ++$i) {
 165                 $ch = $value{$i};
 166                 if(!($ch >= 'a' && $ch <= 'z' || $ch >= 'A' && $ch <= 'Z' || $ch >= '0' && $ch <= '9' || $ch == '-' || $ch == '+')) {
 167                     if($ch == '=' && $len - $i <= 2) {
 168                         continue;
 169                     }
 170                     return false;
 171                 }
 172             }
 173             return true;
 174         break;
 175
 176         case RFC2445_TYPE_BOOLEAN:
 177             if(is_bool($value)) {
 178                 return true;
 179             }
 180             if(is_string($value)) {
 181                 $value = strtoupper($value);
 182                 return ($value == 'TRUE' || $value == 'FALSE');
 183             }
 184             return false;
 185         break;
 186
 187         case RFC2445_TYPE_DATE:
 188             if(is_int($value)) {
 189                 if($value < 0) {
 190                     return false;
 191                 }
 192                 $value = "$value";
 193             }
 194             else if(!is_string($value)) {
 195                 return false;
 196             }
 197
 198             if(strlen($value) != 8) {
 199                 return false;
 200             }
 201
 202             $y = intval(substr($value, 0, 4));
 203             $m = intval(substr($value, 4, 2));
 204             $d = intval(substr($value, 6, 2));
 205
 206             return checkdate($m, $d, $y);
 207         break;
 208
 209         case RFC2445_TYPE_DATE_TIME:
 210             if(!is_string($value) || strlen($value) < 15) {
 211                 return false;
 212             }
 213
 214             return($value{8} == 'T' &&
 215                    rfc2445_is_valid_value(substr($value, 0, 8), RFC2445_TYPE_DATE) &&
 216                    rfc2445_is_valid_value(substr($value, 9), RFC2445_TYPE_TIME));
 217         break;
 218
 219         case RFC2445_TYPE_DURATION:
 220             if(!is_string($value)) {
 221                 return false;
 222             }
 223
 224             $len = strlen($value);
 225
 226             if($len < 3) {
 227                 // Minimum conformant length: "P1W"
 228                 return false;
 229             }
 230
 231             if($value{0} == '+' || $value{0} == '-') {
 232                 $value = substr($value, 1);
 233                 --$len; // Don't forget to update this!
 234             }
 235
 236             if($value{0} != 'P') {
 237                 return false;
 238             }
 239
 240             // OK, now break it up
 241             $num = '';
 242             $allowed = 'WDT';
 243
 244             for($i = 1; $i < $len; ++$i) {
 245                 $ch = $value{$i};
 246                 if($ch >= '0' && $ch <= '9') {
 247                     $num .= $ch;
 248                     continue;
 249                 }
 250                 if(strpos($allowed, $ch) === false) {
 251                     // Non-numeric character which shouldn't be here
 252                     return false;
 253                 }
 254                 if($num === '' && $ch != 'T') {
 255                     // Allowed non-numeric character, but no digits came before it
 256                     return false;
 257                 }
 258
 259                 // OK, $ch now holds a character which tells us what $num is
 260                 switch($ch) {
 261                     case 'W':
 262                         // If duration in weeks is specified, this must end the string
 263                         return ($i == $len - 1);
 264                     break;
 265
 266                     case 'D':
 267                         // Days specified, now if anything comes after it must be a 'T'
 268                         $allowed = 'T';
 269                     break;
 270
 271                     case 'T':
 272                         // Starting to specify time, H M S are now valid delimiters
 273                         $allowed = 'HMS';
 274                     break;
 275
 276                     case 'H':
 277                         $allowed = 'M';
 278                     break;
 279
 280                     case 'M':
 281                         $allowed = 'S';
 282                     break;
 283
 284                     case 'S':
 285                         return ($i == $len - 1);
 286                     break;
 287                 }
 288
 289                 // If we 're going to continue, reset $num
 290                 $num = '';
 291
 292             }
 293
 294             // $num is kept for this reason: if we 're here, we ran out of chars
 295             // therefore $num must be empty for the period to be legal
 296             return ($num === '' && $ch != 'T');
 297
 298         break;
 299
 300         case RFC2445_TYPE_FLOAT:
 301             if(is_float($value)) {
 302                 return true;
 303             }
 304             if(!is_string($value) || $value === '') {
 305                 return false;
 306             }
 307
 308             $dot = false;
 309             $int = false;
 310             $len = strlen($value);
 311             for($i = 0; $i < $len; ++$i) {
 312                 switch($value{$i}) {
 313                     case '-': case '+':
 314                         // A sign can only be seen at position 0 and cannot be the only char
 315                         if($i != 0 || $len == 1) {
 316                             return false;
 317                         }
 318                     break;
 319                     case '.':
 320                         // A second dot is an error
 321                         // Make sure we had at least one int before the dot
 322                         if($dot || !$int) {
 323                             return false;
 324                         }
 325                         $dot = true;
 326                         // Make also sure that the float doesn't end with a dot
 327                         if($i == $len - 1) {
 328                             return false;
 329                         }
 330                     break;
 331                     case '0': case '1': case '2': case '3': case '4':
 332                     case '5': case '6': case '7': case '8': case '9':
 333                         $int = true;
 334                     break;
 335                     default:
 336                         // Any other char is a no-no
 337                         return false;
 338                     break;
 339                 }
 340             }
 341             return true;
 342         break;
 343
 344         case RFC2445_TYPE_INTEGER:
 345             if(is_int($value)) {
 346                 return true;
 347             }
 348             if(!is_string($value) || $value === '') {
 349                 return false;
 350             }
 351
 352             if($value{0} == '+' || $value{0} == '-') {
 353                 if(strlen($value) == 1) {
 354                     return false;
 355                 }
 356                 $value = substr($value, 1);
 357             }
 358
 359             if(strspn($value, '0123456789') != strlen($value)) {
 360                 return false;
 361             }
 362
 363             return ($value >= -2147483648 && $value <= 2147483647);
 364         break;
 365
 366         case RFC2445_TYPE_PERIOD:
 367             if(!is_string($value) || empty($value)) {
 368                 return false;
 369             }
 370
 371             $parts = explode('/', $value);
 372             if(count($parts) != 2) {
 373                 return false;
 374             }
 375
 376             if(!rfc2445_is_valid_value($parts[0], RFC2445_TYPE_DATE_TIME)) {
 377                 return false;
 378             }
 379
 380             // Two legal cases for the second part:
 381             if(rfc2445_is_valid_value($parts[1], RFC2445_TYPE_DATE_TIME)) {
 382                 // It has to be after the start time, so
 383                 return ($parts[1] > $parts[0]);
 384             }
 385             else if(rfc2445_is_valid_value($parts[1], RFC2445_TYPE_DURATION)) {
 386                 // The period MUST NOT be negative
 387                 return ($parts[1]{0} != '-');
 388             }
 389
 390             // It seems to be illegal
 391             return false;
 392         break;
 393
 394         case RFC2445_TYPE_RECUR:
 395             if(!is_string($value)) {
 396                 return false;
 397             }
 398
 399             $parts = explode(';', strtoupper($value));
 400
 401             // We need at least one part for a valid rule, for example: "FREQ=DAILY".
 402             if(empty($parts)) {
 403                 return false;
 404             }
 405
 406             // Let's get that into a more easily comprehensible format
 407             $vars = array();
 408             foreach($parts as $part) {
 409
 410                 $pieces = explode('=', $part);
 411                 // There must be exactly 2 pieces, e.g. FREQ=WEEKLY
 412                 if(count($pieces) != 2) {
 413                     return false;
 414                 }
 415
 416                 // It's illegal for a variable to appear twice
 417                 if(isset($vars[$pieces[0]])) {
 418                     return false;
 419                 }
 420
 421                 // Sounds good
 422                 $vars[$pieces[0]] = $pieces[1];
 423             }
 424
 425             // OK... now to test everything else
 426
 427             // FREQ must be the first thing appearing
 428             reset($vars);
 429             if(key($vars) != 'FREQ') {
 430                 return false;
 431             }
 432
 433             // It's illegal to have both UNTIL and COUNT appear
 434             if(isset($vars['UNTIL']) && isset($vars['COUNT'])) {
 435                 return false;
 436             }
 437
 438             // Special case: BYWEEKNO is only valid for FREQ=YEARLY
 439             if(isset($vars['BYWEEKNO']) && $vars['FREQ'] != 'YEARLY') {
 440                 return false;
 441             }
 442
 443             // Special case: BYSETPOS is only valid if another BY option is specified
 444             if(isset($vars['BYSETPOS'])) {
 445                 $options = array('BYSECOND', 'BYMINUTE', 'BYHOUR', 'BYDAY', 'BYMONTHDAY', 'BYYEARDAY', 'BYWEEKNO', 'BYMONTH');
 446                 $defined = array_keys($vars);
 447                 $common  = array_intersect($options, $defined);
 448                 if(empty($common)) {
 449                     return false;
 450                 }
 451             }
 452
 453             // OK, now simply check if each element has a valid value,
 454             // unsetting them on the way. If at the end the array still
 455             // has some elements, they are illegal.
 456
 457             if($vars['FREQ'] != 'SECONDLY' && $vars['FREQ'] != 'MINUTELY' && $vars['FREQ'] != 'HOURLY' &&
 458                $vars['FREQ'] != 'DAILY'    && $vars['FREQ'] != 'WEEKLY' &&
 459                $vars['FREQ'] != 'MONTHLY'  && $vars['FREQ'] != 'YEARLY') {
 460                 return false;
 461             }
 462             unset($vars['FREQ']);
 463
 464             // Set this, we may need it later
 465             $weekdays = explode(',', RFC2445_WEEKDAYS);
 466
 467             if(isset($vars['UNTIL'])) {
 468                 if(rfc2445_is_valid_value($vars['UNTIL'], RFC2445_TYPE_DATE_TIME)) {
 469                     // The time MUST be in UTC format
 470                     if(!(substr($vars['UNTIL'], -1) == 'Z')) {
 471                         return false;
 472                     }
 473                 }
 474                 else if(!rfc2445_is_valid_value($vars['UNTIL'], RFC2445_TYPE_DATE_TIME)) {
 475                     return false;
 476                 }
 477             }
 478             unset($vars['UNTIL']);
 479
 480
 481             if(isset($vars['COUNT'])) {
 482                 if(empty($vars['COUNT'])) {
 483                     // This also catches the string '0', which makes no sense
 484                     return false;
 485                 }
 486                 if(strspn($vars['COUNT'], '0123456789') != strlen($vars['COUNT'])) {
 487                     return false;
 488                 }
 489             }
 490             unset($vars['COUNT']);
 491
 492
 493             if(isset($vars['INTERVAL'])) {
 494                 if(empty($vars['INTERVAL'])) {
 495                     // This also catches the string '0', which makes no sense
 496                     return false;
 497                 }
 498                 if(strspn($vars['INTERVAL'], '0123456789') != strlen($vars['INTERVAL'])) {
 499                     return false;
 500                 }
 501             }
 502             unset($vars['INTERVAL']);
 503
 504
 505             if(isset($vars['BYSECOND'])) {
 506                 if($vars['BYSECOND'] == '') {
 507                     return false;
 508                 }
 509                 // Comma also allowed
 510                 if(strspn($vars['BYSECOND'], '0123456789,') != strlen($vars['BYSECOND'])) {
 511                     return false;
 512                 }
 513                 $secs = explode(',', $vars['BYSECOND']);
 514                 foreach($secs as $sec) {
 515                     if($sec == '' || $sec < 0 || $sec > 59) {
 516                         return false;
 517                     }
 518                 }
 519             }
 520             unset($vars['BYSECOND']);
 521
 522
 523             if(isset($vars['BYMINUTE'])) {
 524                 if($vars['BYMINUTE'] == '') {
 525                     return false;
 526                 }
 527                 // Comma also allowed
 528                 if(strspn($vars['BYMINUTE'], '0123456789,') != strlen($vars['BYMINUTE'])) {
 529                     return false;
 530                 }
 531                 $mins = explode(',', $vars['BYMINUTE']);
 532                 foreach($mins as $min) {
 533                     if($min == '' || $min < 0 || $min > 59) {
 534                         return false;
 535                     }
 536                 }
 537             }
 538             unset($vars['BYMINUTE']);
 539
 540
 541             if(isset($vars['BYHOUR'])) {
 542                 if($vars['BYHOUR'] == '') {
 543                     return false;
 544                 }
 545                 // Comma also allowed
 546                 if(strspn($vars['BYHOUR'], '0123456789,') != strlen($vars['BYHOUR'])) {
 547                     return false;
 548                 }
 549                 $hours = explode(',', $vars['BYHOUR']);
 550                 foreach($hours as $hour) {
 551                     if($hour == '' || $hour < 0 || $hour > 23) {
 552                         return false;
 553                     }
 554                 }
 555             }
 556             unset($vars['BYHOUR']);
 557
 558
 559             if(isset($vars['BYDAY'])) {
 560                 if(empty($vars['BYDAY'])) {
 561                     return false;
 562                 }
 563
 564                 // First off, split up all values we may have
 565                 $days = explode(',', $vars['BYDAY']);
 566
 567                 foreach($days as $day) {
 568                     $daypart = substr($day, -2);
 569                     if(!in_array($daypart, $weekdays)) {
 570                         return false;
 571                     }
 572
 573                     if(strlen($day) > 2) {
 574                         $intpart = substr($day, 0, strlen($day) - 2);
 575                         if(!rfc2445_is_valid_value($intpart, RFC2445_TYPE_INTEGER)) {
 576                             return false;
 577                         }
 578                         if(intval($intpart) == 0) {
 579                             return false;
 580                         }
 581                     }
 582                 }
 583             }
 584             unset($vars['BYDAY']);
 585
 586
 587             if(isset($vars['BYMONTHDAY'])) {
 588                 if(empty($vars['BYMONTHDAY'])) {
 589                     return false;
 590                 }
 591                 $mdays = explode(',', $vars['BYMONTHDAY']);
 592                 foreach($mdays as $mday) {
 593                     if(!rfc2445_is_valid_value($mday, RFC2445_TYPE_INTEGER)) {
 594                         return false;
 595                     }
 596                     $mday = abs(intval($mday));
 597                     if($mday == 0 || $mday > 31) {
 598                         return false;
 599                     }
 600                 }
 601             }
 602             unset($vars['BYMONTHDAY']);
 603
 604
 605             if(isset($vars['BYYEARDAY'])) {
 606                 if(empty($vars['BYYEARDAY'])) {
 607                     return false;
 608                 }
 609                 $ydays = explode(',', $vars['BYYEARDAY']);
 610                 foreach($ydays as $yday) {
 611                     if(!rfc2445_is_valid_value($yday, RFC2445_TYPE_INTEGER)) {
 612                         return false;
 613                     }
 614                     $yday = abs(intval($yday));
 615                     if($yday == 0 || $yday > 366) {
 616                         return false;
 617                     }
 618                 }
 619             }
 620             unset($vars['BYYEARDAY']);
 621
 622
 623             if(isset($vars['BYWEEKNO'])) {
 624                 if(empty($vars['BYWEEKNO'])) {
 625                     return false;
 626                 }
 627                 $weeknos = explode(',', $vars['BYWEEKNO']);
 628                 foreach($weeknos as $weekno) {
 629                     if(!rfc2445_is_valid_value($weekno, RFC2445_TYPE_INTEGER)) {
 630                         return false;
 631                     }
 632                     $weekno = abs(intval($weekno));
 633                     if($weekno == 0 || $weekno > 53) {
 634                         return false;
 635                     }
 636                 }
 637             }
 638             unset($vars['BYWEEKNO']);
 639
 640
 641             if(isset($vars['BYMONTH'])) {
 642                 if(empty($vars['BYMONTH'])) {
 643                     return false;
 644                 }
 645                 // Comma also allowed
 646                 if(strspn($vars['BYMONTH'], '0123456789,') != strlen($vars['BYMONTH'])) {
 647                     return false;
 648                 }
 649                 $months = explode(',', $vars['BYMONTH']);
 650                 foreach($months as $month) {
 651                     if($month == '' || $month < 1 || $month > 12) {
 652                         return false;
 653                     }
 654                 }
 655             }
 656             unset($vars['BYMONTH']);
 657
 658
 659             if(isset($vars['BYSETPOS'])) {
 660                 if(empty($vars['BYSETPOS'])) {
 661                     return false;
 662                 }
 663                 $sets = explode(',', $vars['BYSETPOS']);
 664                 foreach($sets as $set) {
 665                     if(!rfc2445_is_valid_value($set, RFC2445_TYPE_INTEGER)) {
 666                         return false;
 667                     }
 668                     $set = abs(intval($set));
 669                     if($set == 0 || $set > 366) {
 670                         return false;
 671                     }
 672                 }
 673             }
 674             unset($vars['BYSETPOS']);
 675
 676
 677             if(isset($vars['WKST'])) {
 678                 if(!in_array($vars['WKST'], $weekdays)) {
 679                     return false;
 680                 }
 681             }
 682             unset($vars['WKST']);
 683
 684
 685             // Any remaining vars must be x-names
 686             if(empty($vars)) {
 687                 return true;
 688             }
 689
 690             foreach($vars as $name => $var) {
 691                 if(!rfc2445_is_xname($name)) {
 692                     return false;
 693                 }
 694             }
 695
 696             // At last, all is OK!
 697             return true;
 698
 699         break;
 700
 701         case RFC2445_TYPE_TEXT:
 702             return true;
 703         break;
 704
 705         case RFC2445_TYPE_TIME:
 706             if(is_int($value)) {
 707                 if($value < 0) {
 708                     return false;
 709                 }
 710                 $value = "$value";
 711             }
 712             else if(!is_string($value)) {
 713                 return false;
 714             }
 715
 716             if(strlen($value) == 7) {
 717                 if(strtoupper(substr($value, -1)) != 'Z') {
 718                     return false;
 719                 }
 720                 $value = substr($value, 0, 6);
 721             }
 722             if(strlen($value) != 6) {
 723                 return false;
 724             }
 725
 726             $h = intval(substr($value, 0, 2));
 727             $m = intval(substr($value, 2, 2));
 728             $s = intval(substr($value, 4, 2));
 729
 730             return ($h <= 23 && $m <= 59 && $s <= 60);
 731         break;
 732
 733         case RFC2445_TYPE_UTC_OFFSET:
 734             if(is_int($value)) {
 735                 if($value >= 0) {
 736                     $value = "+$value";
 737                 }
 738                 else {
 739                     $value = "$value";
 740                 }
 741             }
 742             else if(!is_string($value)) {
 743                 return false;
 744             }
 745
 746             $s = 0;
 747             if(strlen($value) == 7) {
 748                 $s = intval(substr($value, 5, 2));
 749                 $value = substr($value, 0, 5);
 750             }
 751             if(strlen($value) != 5 || $value == "-0000") {
 752                 return false;
 753             }
 754
 755             if($value{0} != '+' && $value{0} != '-') {
 756                 return false;
 757             }
 758
 759             $h = intval(substr($value, 1, 2));
 760             $m = intval(substr($value, 3, 2));
 761
 762             return ($h <= 23 && $m <= 59 && $s <= 59);
 763         break;
 764     }
 765
 766     // TODO: remove this assertion
 767     trigger_error('bad code path', E_USER_WARNING);
 768     var_dump($type);
 769     return false;
 770 }
 771
 772 function rfc2445_do_value_formatting($value, $type) {
 773     // Note: this does not only do formatting; it also does conversion to string!
 774     switch($type) {
 775         case RFC2445_TYPE_CAL_ADDRESS:
 776         case RFC2445_TYPE_URI:
 777             // Enclose in double quotes
 778             $value = '"'.$value.'"';
 779         break;
 780         case RFC2445_TYPE_TEXT:
 781             // Escape entities
 782             $value = strtr($value, array("\r\n" => '\\n', "\n" => '\\n', '\\' => '\\\\', ',' => '\\,', ';' => '\\;'));
 783         break;
 784     }
 785     return $value;
 786 }
 787
 788 function rfc2445_undo_value_formatting($value, $type) {
 789     switch($type) {
 790         case RFC2445_TYPE_CAL_ADDRESS:
 791         case RFC2445_TYPE_URI:
 792             // Trim beginning and end double quote
 793             $value = substr($value, 1, strlen($value) - 2);
 794         break;
 795         case RFC2445_TYPE_TEXT:
 796             // Unescape entities
 797             $value = strtr($value, array('\\n' => "\n", '\\N' => "\n", '\\\\' => '\\', '\\,' => ',', '\\;' => ';'));
 798         break;
 799     }
 800     return $value;
 801 }