epan/value_string.c

   1 /* value_string.c
   2  * Routines for value_strings
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include <stdio.h>
  28 #include <string.h>
  29
  30 #include "emem.h"
  31 #include "wmem/wmem.h"
  32 #include "proto.h"
  33 #include "to_str.h"
  34 #include "value_string.h"
  35
  36 /* REGULAR VALUE STRING */
  37
  38 /* Tries to match val against each element in the value_string array vs.
  39    Returns the associated string ptr on a match.
  40    Formats val with fmt, and returns the resulting string, on failure. */
  41 const gchar*
  42 val_to_str(const guint32 val, const value_string *vs, const char *fmt)
  43 {
  44     const gchar *ret;
  45
  46     DISSECTOR_ASSERT(fmt != NULL);
  47
  48     ret = try_val_to_str(val, vs);
  49     if (ret != NULL)
  50         return ret;
  51
  52     return ep_strdup_printf(fmt, val);
  53 }
  54
  55 /* Tries to match val against each element in the value_string array vs.
  56    Returns the associated string ptr on a match.
  57    Returns 'unknown_str', on failure. */
  58 const gchar*
  59 val_to_str_const(const guint32 val, const value_string *vs,
  60         const char *unknown_str)
  61 {
  62     const gchar *ret;
  63
  64     DISSECTOR_ASSERT(unknown_str != NULL);
  65
  66     ret = try_val_to_str(val, vs);
  67     if (ret != NULL)
  68         return ret;
  69
  70     return unknown_str;
  71 }
  72
  73 /* Tries to match val against each element in the value_string array vs.
  74    Returns the associated string ptr, and sets "*idx" to the index in
  75    that table, on a match, and returns NULL, and sets "*idx" to -1,
  76    on failure. */
  77 const gchar*
  78 try_val_to_str_idx(const guint32 val, const value_string *vs, gint *idx)
  79 {
  80     gint i = 0;
  81
  82     DISSECTOR_ASSERT(idx != NULL);
  83
  84     if(vs) {
  85         while (vs[i].strptr) {
  86             if (vs[i].value == val) {
  87                 *idx = i;
  88                 return(vs[i].strptr);
  89             }
  90             i++;
  91         }
  92     }
  93
  94     *idx = -1;
  95     return NULL;
  96 }
  97
  98 /* Like try_val_to_str_idx(), but doesn't return the index. */
  99 const gchar*
 100 try_val_to_str(const guint32 val, const value_string *vs)
 101 {
 102     gint ignore_me;
 103     return try_val_to_str_idx(val, vs, &ignore_me);
 104 }
 105
 106 /* 64-BIT VALUE STRING */
 107
 108 const gchar*
 109 val64_to_str(const guint64 val, const val64_string *vs, const char *fmt)
 110 {
 111     const gchar *ret;
 112
 113     DISSECTOR_ASSERT(fmt != NULL);
 114
 115     ret = try_val64_to_str(val, vs);
 116     if (ret != NULL)
 117         return ret;
 118
 119     return ep_strdup_printf(fmt, val);
 120 }
 121
 122 const gchar*
 123 val64_to_str_const(const guint64 val, const val64_string *vs,
 124         const char *unknown_str)
 125 {
 126     const gchar *ret;
 127
 128     DISSECTOR_ASSERT(unknown_str != NULL);
 129
 130     ret = try_val64_to_str(val, vs);
 131     if (ret != NULL)
 132         return ret;
 133
 134     return unknown_str;
 135 }
 136
 137 const gchar*
 138 try_val64_to_str_idx(const guint64 val, const val64_string *vs, gint *idx)
 139 {
 140     gint i = 0;
 141
 142     DISSECTOR_ASSERT(idx != NULL);
 143
 144     if(vs) {
 145         while (vs[i].strptr) {
 146             if (vs[i].value == val) {
 147                 *idx = i;
 148                 return(vs[i].strptr);
 149             }
 150             i++;
 151         }
 152     }
 153
 154     *idx = -1;
 155     return NULL;
 156 }
 157
 158 const gchar*
 159 try_val64_to_str(const guint64 val, const val64_string *vs)
 160 {
 161     gint ignore_me;
 162     return try_val64_to_str_idx(val, vs, &ignore_me);
 163 }
 164
 165 /* REVERSE VALUE STRING */
 166
 167 /* We use the same struct as for regular value strings, but we look up strings
 168  * and return values instead */
 169
 170 /* Like val_to_str except backwards */
 171 guint32
 172 str_to_val(const gchar *val, const value_string *vs, const guint32 err_val)
 173 {
 174     gint i;
 175
 176     i = str_to_val_idx(val, vs);
 177
 178     if (i >= 0) {
 179         return vs[i].value;
 180     }
 181
 182     return err_val;
 183 }
 184
 185 /* Find the index of a string in a value_string, or -1 when not present */
 186 gint
 187 str_to_val_idx(const gchar *val, const value_string *vs)
 188 {
 189     gint i = 0;
 190
 191     if(vs) {
 192
 193         while (vs[i].strptr) {
 194
 195             if (strcmp(vs[i].strptr, val) == 0) {
 196                 return i;
 197             }
 198
 199             i++;
 200         }
 201
 202     }
 203
 204     return -1;
 205 }
 206
 207 /* EXTENDED VALUE STRING */
 208
 209 /* Extended value strings allow fast(er) value_string array lookups by
 210  * using (if possible) direct access or a binary search of the array.
 211  *
 212  * If the values in the value_string array are a contiguous range of values
 213  * from min to max, the value will be used as as a direct index into the array.
 214  *
 215  * If the values in the array are not contiguous (ie: there are "gaps"),
 216  * but are in assending order a binary search will be used.
 217  *
 218  * If direct access or binary search cannot be used, then a linear search
 219  * is used and a warning is emitted.
 220  *
 221  * Note that the value_string array used with VALUE_STRING_EXT_INIT
 222  * *must* be terminated with {0, NULL}).
 223  *
 224  * Extended value strings are defined at compile time as follows:
 225  *   static const value_string vs[] = { {value1, "string1"},
 226  *                                      {value2, "string2"},
 227  *                                      ...,
 228  *                                      {0, NULL}};
 229  *   static value_string_ext vse = VALUE_STRING_EXT_INIT(vs);
 230  *
 231  * Extended value strings can be created at runtime by calling
 232  *   value_string_ext_new(<ptr to value_string array>,
 233  *                        <total number of entries in the value_string_array>,
 234  *                        <value_string_name>);
 235  * Note: The <total number of entries in the value_string_array> should include
 236  *       the {0, NULL} entry.
 237  */
 238
 239 /* Create a value_string_ext given a ptr to a value_string array and the total
 240  * number of entries. Note that the total number of entries should include the
 241  * required {0, NULL} terminating entry of the array.
 242  * Returns a pointer to an epan-scoped'd and initialized value_string_ext
 243  * struct. */
 244 value_string_ext *
 245 value_string_ext_new(value_string *vs, guint vs_tot_num_entries,
 246         const gchar *vs_name)
 247 {
 248     value_string_ext *vse;
 249
 250     DISSECTOR_ASSERT (vs_name != NULL);
 251     DISSECTOR_ASSERT (vs_tot_num_entries > 0);
 252     /* Null-terminated value-string ? */
 253     DISSECTOR_ASSERT (vs[vs_tot_num_entries-1].strptr == NULL);
 254
 255     vse                  = wmem_new(wmem_epan_scope(), value_string_ext);
 256     vse->_vs_p           = vs;
 257     vse->_vs_num_entries = vs_tot_num_entries - 1;
 258     /* We set our 'match' function to the init function, which finishes by
 259      * setting the match function properly and then calling it. This is a
 260      * simple way to do lazy initialization of extended value strings.
 261      * The init function also sets up _vs_first_value for us. */
 262     vse->_vs_first_value = 0;
 263     vse->_vs_match2      = _try_val_to_str_ext_init;
 264     vse->_vs_name        = vs_name;
 265
 266     return vse;
 267 }
 268
 269 /* Like try_val_to_str for extended value strings */
 270 const gchar*
 271 try_val_to_str_ext(const guint32 val, const value_string_ext *vse)
 272 {
 273     if (vse) {
 274         const value_string *vs = vse->_vs_match2(val, vse);
 275
 276         if (vs) {
 277             return vs->strptr;
 278         }
 279     }
 280
 281     return NULL;
 282 }
 283
 284 /* Like try_val_to_str_idx for extended value strings */
 285 const gchar*
 286 try_val_to_str_idx_ext(const guint32 val, value_string_ext *vse, gint *idx)
 287 {
 288     if (vse) {
 289         const value_string *vs = vse->_vs_match2(val, vse);
 290         if (vs) {
 291             *idx = (gint) (vs - vse->_vs_p);
 292             return vs->strptr;
 293         }
 294     }
 295     *idx = -1;
 296     return NULL;
 297 }
 298
 299 /* Like val_to_str for extended value strings */
 300 const gchar*
 301 val_to_str_ext(const guint32 val, const value_string_ext *vse, const char *fmt)
 302 {
 303     const gchar *ret;
 304
 305     DISSECTOR_ASSERT(fmt != NULL);
 306
 307     ret = try_val_to_str_ext(val, vse);
 308     if (ret != NULL)
 309         return ret;
 310
 311     return ep_strdup_printf(fmt, val);
 312 }
 313
 314 /* Like val_to_str_const for extended value strings */
 315 const gchar*
 316 val_to_str_ext_const(const guint32 val, const value_string_ext *vse,
 317         const char *unknown_str)
 318 {
 319     const gchar *ret;
 320
 321     DISSECTOR_ASSERT(unknown_str != NULL);
 322
 323     ret = try_val_to_str_ext(val, vse);
 324     if (ret != NULL)
 325         return ret;
 326
 327     return unknown_str;
 328 }
 329
 330 /* Fallback linear matching algorithm for extended value strings */
 331 static const value_string *
 332 _try_val_to_str_linear(const guint32 val, const value_string_ext *vse)
 333 {
 334     const value_string *vs_p = vse->_vs_p;
 335     guint i;
 336     for (i=0; i<vse->_vs_num_entries; i++) {
 337         if (vs_p[i].value == val)
 338             return &(vs_p[i]);
 339     }
 340     return NULL;
 341 }
 342
 343 /* Constant-time matching algorithm for contiguous extended value strings */
 344 static const value_string *
 345 _try_val_to_str_index(const guint32 val, const value_string_ext *vse)
 346 {
 347     guint i;
 348
 349     i = val - vse->_vs_first_value;
 350     if (i < vse->_vs_num_entries) {
 351         g_assert (val == vse->_vs_p[i].value);
 352         return &(vse->_vs_p[i]);
 353     }
 354     return NULL;
 355 }
 356
 357 /* log(n)-time matching algorithm for sorted extended value strings */
 358 static const value_string *
 359 _try_val_to_str_bsearch(const guint32 val, const value_string_ext *vse)
 360 {
 361     guint low, i, max;
 362     guint32 item;
 363
 364     for (low = 0, max = vse->_vs_num_entries; low < max; ) {
 365         i = (low + max) / 2;
 366         item = vse->_vs_p[i].value;
 367
 368         if (val < item)
 369             max = i;
 370         else if (val > item)
 371             low = i + 1;
 372         else
 373             return &(vse->_vs_p[i]);
 374     }
 375     return NULL;
 376 }
 377
 378 /* Initializes an extended value string. Behaves like a match function to
 379  * permit lazy initialization of extended value strings.
 380  * - Goes through the value_string array to determine the fastest possible
 381  *   access method.
 382  * - Verifies that the value_string contains no NULL string pointers.
 383  * - Verifies that the value_string is terminated by {0, NULL}
 384  */
 385 const value_string *
 386 _try_val_to_str_ext_init(const guint32 val, const value_string_ext *a_vse)
 387 {
 388     /* Cast away the constness!
 389      * It's better if the prototype for this function matches the other
 390      * _try_val_to_str_* functions (so we don't have to cast it when storing it
 391      * in _try_val_to_str so the compiler will notice if the prototypes get out
 392      * of sync), but the init function is unique in that it does actually
 393      * modify the vse.
 394      */
 395     value_string_ext    *vse            = (value_string_ext *)a_vse;
 396
 397     const value_string *vs_p           = vse->_vs_p;
 398     const guint         vs_num_entries = vse->_vs_num_entries;
 399
 400     /* The matching algorithm used:
 401      * VS_SEARCH   - slow sequential search (as in a normal value string)
 402      * VS_BIN_TREE - log(n)-time binary search, the values must be sorted
 403      * VS_INDEX    - constant-time index lookup, the values must be contiguous
 404      */
 405     enum { VS_SEARCH, VS_BIN_TREE, VS_INDEX } type = VS_INDEX;
 406
 407     /* Note: The value_string 'value' is *unsigned*, but we do a little magic
 408      * to help with value strings that have negative values.
 409      *
 410      * { -3, -2, -1, 0, 1, 2 }
 411      * will be treated as "ascending ordered" (although it isn't technically),
 412      * thus allowing constant-time index search
 413      *
 414      * { -3, -2, 0, 1, 2 } and { -3, -2, -1, 0, 2 }
 415      * will both be considered as "out-of-order with gaps", thus falling
 416      * back to the slow linear search
 417      *
 418      * { 0, 1, 2, -3, -2 } and { 0, 2, -3, -2, -1 }
 419      * will be considered "ascending ordered with gaps" thus allowing
 420      * a log(n)-time 'binary' search
 421      *
 422      * If you're confused, think of how negative values are represented, or
 423      * google two's complement.
 424      */
 425
 426     guint32 prev_value;
 427     guint   first_value;
 428     guint   i;
 429
 430     DISSECTOR_ASSERT((vs_p[vs_num_entries].value  == 0) &&
 431                      (vs_p[vs_num_entries].strptr == NULL));
 432
 433     vse->_vs_first_value = vs_p[0].value;
 434     first_value          = vs_p[0].value;
 435     prev_value           = first_value;
 436
 437     for (i = 0; i < vs_num_entries; i++) {
 438         DISSECTOR_ASSERT(vs_p[i].strptr != NULL);
 439         if ((type == VS_INDEX) && (vs_p[i].value != (i + first_value))) {
 440             type = VS_BIN_TREE;
 441         }
 442         /* XXX: Should check for dups ?? */
 443         if (type == VS_BIN_TREE) {
 444             if (prev_value > vs_p[i].value) {
 445                 g_warning("Extended value string %s forced to fall back to linear search: entry %u, value %u < previous entry, value %u",
 446                         vse->_vs_name, i, vs_p[i].value, prev_value);
 447                 type = VS_SEARCH;
 448                 break;
 449             }
 450             if (first_value > vs_p[i].value) {
 451                 g_warning("Extended value string %s forced to fall back to linear search: entry %u, value %u < first entry, value %u",
 452                         vse->_vs_name, i, vs_p[i].value, first_value);
 453                 type = VS_SEARCH;
 454                 break;
 455             }
 456         }
 457
 458         prev_value = vs_p[i].value;
 459     }
 460
 461     switch (type) {
 462         case VS_SEARCH:
 463             vse->_vs_match2 = _try_val_to_str_linear;
 464             break;
 465         case VS_BIN_TREE:
 466             vse->_vs_match2 = _try_val_to_str_bsearch;
 467             break;
 468         case VS_INDEX:
 469             vse->_vs_match2 = _try_val_to_str_index;
 470             break;
 471         default:
 472             g_assert_not_reached();
 473             break;
 474     }
 475
 476     return vse->_vs_match2(val, vse);
 477 }
 478
 479 /* STRING TO STRING MATCHING */
 480
 481 /* string_string is like value_string except the values being matched are
 482  * also strings (instead of unsigned integers) */
 483
 484 /* Like val_to_str except for string_string */
 485 const gchar*
 486 str_to_str(const gchar *val, const string_string *vs, const char *fmt)
 487 {
 488     const gchar *ret;
 489
 490     DISSECTOR_ASSERT(fmt != NULL);
 491
 492     ret = try_str_to_str(val, vs);
 493     if (ret != NULL)
 494         return ret;
 495
 496     return ep_strdup_printf(fmt, val);
 497 }
 498
 499 /* Like try_val_to_str_idx except for string_string */
 500 const gchar*
 501 try_str_to_str_idx(const gchar *val, const string_string *vs, gint *idx)
 502 {
 503     gint i = 0;
 504
 505     if(vs) {
 506         while (vs[i].strptr) {
 507             if (!strcmp(vs[i].value,val)) {
 508                 *idx = i;
 509                 return(vs[i].strptr);
 510             }
 511             i++;
 512         }
 513     }
 514
 515     *idx = -1;
 516     return NULL;
 517 }
 518
 519 /* Like try_val_to_str except for string_string */
 520 const gchar*
 521 try_str_to_str(const gchar *val, const string_string *vs)
 522 {
 523     gint ignore_me;
 524     return try_str_to_str_idx(val, vs, &ignore_me);
 525 }
 526
 527 /* RANGE TO STRING MATCHING */
 528
 529 /* range_string is like value_string except the values being matched are
 530  * integer ranges (for example, 0-10, 11-19, etc.) instead of single values. */
 531
 532 /* Like val_to_str except for range_string */
 533 const gchar *
 534 rval_to_str(const guint32 val, const range_string *rs, const char *fmt)
 535 {
 536     const gchar *ret = NULL;
 537
 538     DISSECTOR_ASSERT(fmt != NULL);
 539
 540     ret = try_rval_to_str(val, rs);
 541     if(ret != NULL)
 542         return ret;
 543
 544     return ep_strdup_printf(fmt, val);
 545 }
 546
 547 /* Like val_to_str_const except for range_string */
 548 const gchar *
 549 rval_to_str_const(const guint32 val, const range_string *rs,
 550         const char *unknown_str)
 551 {
 552     const gchar *ret = NULL;
 553
 554     DISSECTOR_ASSERT(unknown_str != NULL);
 555
 556     ret = try_rval_to_str(val, rs);
 557     if(ret != NULL)
 558         return ret;
 559
 560     return unknown_str;
 561 }
 562
 563 /* Like try_val_to_str_idx except for range_string */
 564 const gchar *
 565 try_rval_to_str_idx(const guint32 val, const range_string *rs, gint *idx)
 566 {
 567     gint i = 0;
 568
 569     if(rs) {
 570         while(rs[i].strptr) {
 571             if( (val >= rs[i].value_min) && (val <= rs[i].value_max) ) {
 572                 *idx = i;
 573                 return (rs[i].strptr);
 574             }
 575             i++;
 576         }
 577     }
 578
 579     *idx = -1;
 580     return NULL;
 581 }
 582
 583 /* Like try_val_to_str except for range_string */
 584 const gchar *
 585 try_rval_to_str(const guint32 val, const range_string *rs)
 586 {
 587     gint ignore_me = 0;
 588     return try_rval_to_str_idx(val, rs, &ignore_me);
 589 }
 590
 591 /* MISC */
 592
 593 /* Functions for use by proto_registrar_dump_values(), see proto.c */
 594
 595 gboolean
 596 value_string_ext_validate(const value_string_ext *vse)
 597 {
 598     if (vse == NULL)
 599         return FALSE;
 600     if ((vse->_vs_match2 == _try_val_to_str_ext_init) ||
 601             (vse->_vs_match2 == _try_val_to_str_linear)   ||
 602             (vse->_vs_match2 == _try_val_to_str_bsearch)  ||
 603             (vse->_vs_match2 == _try_val_to_str_index))
 604         return TRUE;
 605     return FALSE;
 606 }
 607
 608 const gchar *
 609 value_string_ext_match_type_str(const value_string_ext *vse)
 610 {
 611     if (vse->_vs_match2 == _try_val_to_str_linear)
 612         return "[Linear Search]";
 613     if (vse->_vs_match2 == _try_val_to_str_bsearch)
 614         return "[Binary Search]";
 615     if (vse->_vs_match2 == _try_val_to_str_index)
 616         return "[Direct (indexed) Access]";
 617     return "[Match Type not initialized or invalid]";
 618 }
 619
 620 /*
 621  * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 622  *
 623  * Local variables:
 624  * c-basic-offset: 4
 625  * tab-width: 8
 626  * indent-tabs-mode: nil
 627  * End:
 628  *
 629  * vi: set shiftwidth=4 tabstop=8 expandtab:
 630  * :indentSize=4:tabSize=8:noTabs=true:
 631  */