external/bsd/openldap/dist/libraries/librewrite/rule.c

   1 /* $OpenLDAP: pkg/ldap/libraries/librewrite/rule.c,v 1.23.2.3 2008/02/11 23:26:42 kurt Exp $ */
   2 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   3  *
   4  * Copyright 2000-2008 The OpenLDAP Foundation.
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted only as authorized by the OpenLDAP
   9  * Public License.
  10  *
  11  * A copy of this license is available in the file LICENSE in the
  12  * top-level directory of the distribution or, alternatively, at
  13  * <http://www.OpenLDAP.org/license.html>.
  14  */
  15 /* ACKNOWLEDGEMENT:
  16  * This work was initially developed by Pierangelo Masarati for
  17  * inclusion in OpenLDAP Software.
  18  */
  19
  20 #include <portable.h>
  21
  22 #include "rewrite-int.h"
  23
  24 /*
  25  * Appends a rule to the double linked list of rules
  26  * Helper for rewrite_rule_compile
  27  */
  28 static int
  29 append_rule(
  30                 struct rewrite_context *context,
  31                 struct rewrite_rule *rule
  32 )
  33 {
  34         struct rewrite_rule *r;
  35
  36         assert( context != NULL );
  37         assert( context->lc_rule != NULL );
  38         assert( rule != NULL );
  39
  40         for ( r = context->lc_rule; r->lr_next != NULL; r = r->lr_next );
  41         r->lr_next = rule;
  42         rule->lr_prev = r;
  43
  44         return REWRITE_SUCCESS;
  45 }
  46
  47 /*
  48  * Appends an action to the linked list of actions
  49  * Helper for rewrite_rule_compile
  50  */
  51 static int
  52 append_action(
  53                 struct rewrite_action **pbase,
  54                 struct rewrite_action *action
  55 )
  56 {
  57         struct rewrite_action **pa;
  58
  59         assert( pbase != NULL );
  60         assert( action != NULL );
  61
  62         for ( pa = pbase; *pa != NULL; pa = &(*pa)->la_next );
  63         *pa = action;
  64
  65         return REWRITE_SUCCESS;
  66 }
  67
  68 static int
  69 destroy_action(
  70                 struct rewrite_action **paction
  71 )
  72 {
  73         struct rewrite_action   *action;
  74
  75         assert( paction != NULL );
  76         assert( *paction != NULL );
  77
  78         action = *paction;
  79
  80         /* do something */
  81         switch ( action->la_type ) {
  82         case REWRITE_FLAG_GOTO:
  83         case REWRITE_FLAG_USER: {
  84                 int *pi = (int *)action->la_args;
  85
  86                 if ( pi ) {
  87                         free( pi );
  88                 }
  89                 break;
  90         }
  91
  92         default:
  93                 break;
  94         }
  95
  96         free( action );
  97         *paction = NULL;
  98
  99         return 0;
 100 }
 101
 102 static void
 103 destroy_actions(
 104         struct rewrite_action *paction
 105 )
 106 {
 107         struct rewrite_action *next;
 108
 109         for (; paction; paction = next) {
 110                 next = paction->la_next;
 111                 destroy_action( &paction );
 112         }
 113 }
 114
 115 /*
 116  */
 117 int
 118 rewrite_rule_compile(
 119                 struct rewrite_info *info,
 120                 struct rewrite_context *context,
 121                 const char *pattern,
 122                 const char *result,
 123                 const char *flagstring
 124 )
 125 {
 126         int flags = REWRITE_REGEX_EXTENDED | REWRITE_REGEX_ICASE;
 127         int mode = REWRITE_RECURSE;
 128         int max_passes = info->li_max_passes_per_rule;
 129
 130         struct rewrite_rule *rule = NULL;
 131         struct rewrite_subst *subst = NULL;
 132         struct rewrite_action *action = NULL, *first_action = NULL;
 133
 134         const char *p;
 135
 136         assert( info != NULL );
 137         assert( context != NULL );
 138         assert( pattern != NULL );
 139         assert( result != NULL );
 140
 141         /*
 142          * A null flagstring should be allowed
 143          */
 144
 145         /*
 146          * Take care of substitution string
 147          */
 148         subst = rewrite_subst_compile( info, result );
 149         if ( subst == NULL ) {
 150                 return REWRITE_ERR;
 151         }
 152
 153         /*
 154          * Take care of flags
 155          */
 156         for ( p = flagstring; p[ 0 ] != '\0'; p++ ) {
 157                 switch( p[ 0 ] ) {
 158
 159                 /*
 160                  * REGEX flags
 161                  */
 162                 case REWRITE_FLAG_HONORCASE:            /* 'C' */
 163                         /*
 164                          * Honor case (default is case insensitive)
 165                          */
 166                         flags &= ~REWRITE_REGEX_ICASE;
 167                         break;
 168
 169                 case REWRITE_FLAG_BASICREGEX:           /* 'R' */
 170                         /*
 171                          * Use POSIX Basic Regular Expression syntax
 172                          * instead of POSIX Extended Regular Expression
 173                          * syntax (default)
 174                          */
 175                         flags &= ~REWRITE_REGEX_EXTENDED;
 176                         break;
 177
 178                 /*
 179                  * Execution mode flags
 180                  */
 181                 case REWRITE_FLAG_EXECONCE:             /* ':' */
 182                         /*
 183                          * Apply rule once only
 184                          */
 185                         mode &= ~REWRITE_RECURSE;
 186                         mode |= REWRITE_EXEC_ONCE;
 187                         break;
 188
 189                 /*
 190                  * Special action flags
 191                  */
 192                 case REWRITE_FLAG_STOP:                 /* '@' */
 193                         /*
 194                          * Bail out after applying rule
 195                          */
 196                         action = calloc( sizeof( struct rewrite_action ), 1 );
 197                         if ( action == NULL ) {
 198                                 goto fail;
 199                         }
 200
 201                         action->la_type = REWRITE_ACTION_STOP;
 202                         break;
 203
 204                 case REWRITE_FLAG_UNWILLING:            /* '#' */
 205                         /*
 206                          * Matching objs will be marked as gone!
 207                          */
 208                         action = calloc( sizeof( struct rewrite_action ), 1 );
 209                         if ( action == NULL ) {
 210                                 goto fail;
 211                         }
 212
 213                         mode &= ~REWRITE_RECURSE;
 214                         mode |= REWRITE_EXEC_ONCE;
 215                         action->la_type = REWRITE_ACTION_UNWILLING;
 216                         break;
 217
 218                 case REWRITE_FLAG_GOTO:                         /* 'G' */
 219                         /*
 220                          * After applying rule, jump N rules
 221                          */
 222
 223                 case REWRITE_FLAG_USER: {                       /* 'U' */
 224                         /*
 225                          * After applying rule, return user-defined
 226                          * error code
 227                          */
 228                         char *next = NULL;
 229                         int *d;
 230
 231                         if ( p[ 1 ] != '{' ) {
 232                                 goto fail;
 233                         }
 234
 235                         d = malloc( sizeof( int ) );
 236                         if ( d == NULL ) {
 237                                 goto fail;
 238                         }
 239
 240                         d[ 0 ] = strtol( &p[ 2 ], &next, 0 );
 241                         if ( next == &p[ 2 ] || next[0] != '}' ) {
 242                                 free( d );
 243                                 goto fail;
 244                         }
 245
 246                         action = calloc( sizeof( struct rewrite_action ), 1 );
 247                         if ( action == NULL ) {
 248                                 free( d );
 249                                 goto fail;
 250                         }
 251                         switch ( p[ 0 ] ) {
 252                         case REWRITE_FLAG_GOTO:
 253                                 action->la_type = REWRITE_ACTION_GOTO;
 254                                 break;
 255
 256                         case REWRITE_FLAG_USER:
 257                                 action->la_type = REWRITE_ACTION_USER;
 258                                 break;
 259
 260                         default:
 261                                 assert(0);
 262                         }
 263
 264                         action->la_args = (void *)d;
 265
 266                         p = next;       /* p is incremented by the for ... */
 267
 268                         break;
 269                 }
 270
 271                 case REWRITE_FLAG_MAX_PASSES: {                 /* 'U' */
 272                         /*
 273                          * Set the number of max passes per rule
 274                          */
 275                         char *next = NULL;
 276
 277                         if ( p[ 1 ] != '{' ) {
 278                                 goto fail;
 279                         }
 280
 281                         max_passes = strtol( &p[ 2 ], &next, 0 );
 282                         if ( next == &p[ 2 ] || next[0] != '}' ) {
 283                                 goto fail;
 284                         }
 285
 286                         if ( max_passes < 1 ) {
 287                                 /* FIXME: nonsense ... */
 288                                 max_passes = 1;
 289                         }
 290
 291                         p = next;       /* p is incremented by the for ... */
 292
 293                         break;
 294                 }
 295
 296                 case REWRITE_FLAG_IGNORE_ERR:               /* 'I' */
 297                         /*
 298                          * Ignore errors!
 299                          */
 300                         action = calloc( sizeof( struct rewrite_action ), 1 );
 301                         if ( action == NULL ) {
 302                                 goto fail;
 303                         }
 304
 305                         action->la_type = REWRITE_ACTION_IGNORE_ERR;
 306                         break;
 307
 308                 /*
 309                  * Other flags ...
 310                  */
 311                 default:
 312                         /*
 313                          * Unimplemented feature (complain only)
 314                          */
 315                         break;
 316                 }
 317
 318                 /*
 319                  * Stupid way to append to a list ...
 320                  */
 321                 if ( action != NULL ) {
 322                         append_action( &first_action, action );
 323                         action = NULL;
 324                 }
 325         }
 326
 327         /*
 328          * Finally, rule allocation
 329          */
 330         rule = calloc( sizeof( struct rewrite_rule ), 1 );
 331         if ( rule == NULL ) {
 332                 goto fail;
 333         }
 334
 335         /*
 336          * REGEX compilation (luckily I don't need to take care of this ...)
 337          */
 338         if ( regcomp( &rule->lr_regex, ( char * )pattern, flags ) != 0 ) {
 339                 free( rule );
 340                 goto fail;
 341         }
 342
 343         /*
 344          * Just to remember them ...
 345          */
 346         rule->lr_pattern = strdup( pattern );
 347         rule->lr_subststring = strdup( result );
 348         rule->lr_flagstring = strdup( flagstring );
 349
 350         /*
 351          * Load compiled data into rule
 352          */
 353         rule->lr_subst = subst;
 354
 355         /*
 356          * Set various parameters
 357          */
 358         rule->lr_flags = flags;         /* don't really need any longer ... */
 359         rule->lr_mode = mode;
 360         rule->lr_max_passes = max_passes;
 361         rule->lr_action = first_action;
 362
 363         /*
 364          * Append rule at the end of the rewrite context
 365          */
 366         append_rule( context, rule );
 367
 368         return REWRITE_SUCCESS;
 369
 370 fail:
 371         destroy_actions( first_action );
 372         free( subst );
 373         return REWRITE_ERR;
 374 }
 375
 376 /*
 377  * Rewrites string according to rule; may return:
 378  *      OK:     fine; if *result != NULL rule matched and rewrite succeeded.
 379  *      STOP:   fine, rule matched; stop processing following rules
 380  *      UNWILL: rule matched; force 'unwilling to perform'
 381  */
 382 int
 383 rewrite_rule_apply(
 384                 struct rewrite_info *info,
 385                 struct rewrite_op *op,
 386                 struct rewrite_rule *rule,
 387                 const char *arg,
 388                 char **result
 389                 )
 390 {
 391         size_t nmatch = REWRITE_MAX_MATCH;
 392         regmatch_t match[ REWRITE_MAX_MATCH ];
 393
 394         int rc = REWRITE_SUCCESS;
 395
 396         char *string;
 397         int strcnt = 0;
 398         struct berval val = { 0, NULL };
 399
 400         assert( info != NULL );
 401         assert( op != NULL );
 402         assert( rule != NULL );
 403         assert( arg != NULL );
 404         assert( result != NULL );
 405
 406         *result = NULL;
 407
 408         string = (char *)arg;
 409
 410         /*
 411          * In case recursive match is required (default)
 412          */
 413 recurse:;
 414
 415         Debug( LDAP_DEBUG_TRACE, "==> rewrite_rule_apply"
 416                         " rule='%s' string='%s' [%d pass(es)]\n",
 417                         rule->lr_pattern, string, strcnt + 1 );
 418
 419         op->lo_num_passes++;
 420
 421         rc = regexec( &rule->lr_regex, string, nmatch, match, 0 );
 422         if ( rc != 0 ) {
 423                 if ( *result == NULL && string != arg ) {
 424                         free( string );
 425                 }
 426
 427                 /*
 428                  * No match is OK; *result = NULL means no match
 429                  */
 430                 return REWRITE_REGEXEC_OK;
 431         }
 432
 433         rc = rewrite_subst_apply( info, op, rule->lr_subst, string,
 434                         match, &val );
 435
 436         *result = val.bv_val;
 437         val.bv_val = NULL;
 438         if ( string != arg ) {
 439                 free( string );
 440                 string = NULL;
 441         }
 442
 443         if ( rc != REWRITE_REGEXEC_OK ) {
 444                 return rc;
 445         }
 446
 447         if ( ( rule->lr_mode & REWRITE_RECURSE ) == REWRITE_RECURSE
 448                         && op->lo_num_passes < info->li_max_passes
 449                         && ++strcnt < rule->lr_max_passes ) {
 450                 string = *result;
 451
 452                 goto recurse;
 453         }
 454
 455         return REWRITE_REGEXEC_OK;
 456 }
 457
 458 int
 459 rewrite_rule_destroy(
 460                 struct rewrite_rule **prule
 461                 )
 462 {
 463         struct rewrite_rule *rule;
 464
 465         assert( prule != NULL );
 466         assert( *prule != NULL );
 467
 468         rule = *prule;
 469
 470         if ( rule->lr_pattern ) {
 471                 free( rule->lr_pattern );
 472                 rule->lr_pattern = NULL;
 473         }
 474
 475         if ( rule->lr_subststring ) {
 476                 free( rule->lr_subststring );
 477                 rule->lr_subststring = NULL;
 478         }
 479
 480         if ( rule->lr_flagstring ) {
 481                 free( rule->lr_flagstring );
 482                 rule->lr_flagstring = NULL;
 483         }
 484
 485         if ( rule->lr_subst ) {
 486                 rewrite_subst_destroy( &rule->lr_subst );
 487         }
 488
 489         regfree( &rule->lr_regex );
 490
 491         destroy_actions( rule->lr_action );
 492
 493         free( rule );
 494         *prule = NULL;
 495
 496         return 0;
 497 }
 498