mdw@git.distorted.org.uk Git - fwd/blob - conf.c

   1 /* -*-c-*-
   2  *
   3  * $Id: conf.c,v 1.7 2000/08/01 17:58:10 mdw Exp $
   4  *
   5  * Configuration parsing
   6  *
   7  * (c) 1999 Straylight/Edgeware
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of the `fw' port forwarder.
  13  *
  14  * `fw' is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * `fw' is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with `fw'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: conf.c,v $
  32  * Revision 1.7  2000/08/01 17:58:10  mdw
  33  * Fix subtleties with <ctype.h> functions.
  34  *
  35  * Revision 1.6  2000/02/12 18:13:20  mdw
  36  * Terminate tables of sources and targets.
  37  *
  38  * Revision 1.5  1999/10/22 22:46:44  mdw
  39  * Improve documentation for conf_enum.
  40  *
  41  * Revision 1.4  1999/10/15 21:12:36  mdw
  42  * Remove redundant debugging code.
  43  *
  44  * Revision 1.3  1999/08/19 18:32:48  mdw
  45  * Improve lexical analysis.  In particular, `chmod' patterns don't have to
  46  * be quoted any more.
  47  *
  48  * Revision 1.2  1999/07/26 23:28:39  mdw
  49  * Major reconstruction work for new design.
  50  *
  51  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  52  * Initial revision.
  53  *
  54  */
  55
  56 /*----- Header files ------------------------------------------------------*/
  57
  58 #include "config.h"
  59
  60 #include <ctype.h>
  61 #include <errno.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <string.h>
  66
  67 #include <mLib/dstr.h>
  68 #include <mLib/quis.h>
  69 #include <mLib/report.h>
  70
  71 #include "conf.h"
  72 #include "scan.h"
  73 #include "source.h"
  74 #include "target.h"
  75
  76 #include "exec.h"
  77 #include "file.h"
  78 #include "socket.h"
  79
  80 /*----- Source and target tables ------------------------------------------*/
  81
  82 static source_ops *sources[] =
  83   { &xsource_ops, &fsource_ops, &ssource_ops, 0 };
  84 static target_ops *targets[] =
  85   { &xtarget_ops, &ftarget_ops, &starget_ops, 0 };
  86
  87 static const char *notword = 0;
  88 static const char *notdelim = 0;
  89
  90 /*----- Main code ---------------------------------------------------------*/
  91
  92 /* --- @undelim@ --- *
  93  *
  94  * Arguments:   @const char *d, dd@ = pointer to characters to escape
  95  *
  96  * Returns:     ---
  97  *
  98  * Use:         Modifies the tokenizer.  Characters in the first list will
  99  *              always be considered to begin a word.  Characters in the
 100  *              second list will always be allowed to continue a word.
 101  */
 102
 103 void undelim(const char *d, const char *dd) { notword = d; notdelim = dd; }
 104
 105 /* --- @token@ --- *
 106  *
 107  * Arguments:   @scanner *sc@ = pointer to scanner definition
 108  *
 109  * Returns:     Type of token scanned.
 110  *
 111  * Use:         Reads the next token from the character scanner.
 112  */
 113
 114 int token(scanner *sc)
 115 {
 116 #define SELFDELIM \
 117   '{': case '}': case '/': case ',': \
 118   case '=': case ':': case ';': \
 119   case '.': case '[': case ']'
 120
 121   int ch;
 122
 123   DRESET(&sc->d);
 124
 125   /* --- Main tokenization --- */
 126
 127   for (;;) {
 128     ch = scan(sc);
 129
 130     /* --- Deal with pushed-back tokens --- */
 131
 132     if (sc->head->tok) {
 133       dstr_puts(&sc->d, sc->head->tok);
 134       free(sc->head->tok);
 135       sc->head->tok = 0;
 136       sc->t = sc->head->t;
 137       goto done;
 138     }
 139
 140     else if (isspace(ch))
 141       ;
 142     else switch (ch) {
 143
 144       /* --- End of file --- */
 145
 146       case EOF:
 147         sc->t = CTOK_EOF;
 148         goto done;
 149
 150       /* --- Comment character --- */
 151
 152       case '#':
 153         do ch = scan(sc); while (ch != EOF && ch != '\n');
 154         break;
 155
 156       /* --- Various self-delimiting characters --- */
 157
 158       case SELFDELIM:
 159         if (!notword || strchr(notword, ch) == 0) {
 160           dstr_putc(&sc->d, ch);
 161           dstr_putz(&sc->d);
 162           sc->t = ch;
 163           goto done;
 164         }
 165
 166       /* --- Bare words --- *
 167        *
 168        * These aren't as bare any more.  You can now backslash-escape
 169        * individual characters, and enclose sections in double-quotes.
 170        */
 171
 172       default: {
 173         int q = 0;
 174
 175         for (;;) {
 176           switch (ch) {
 177             case EOF:
 178               goto word;
 179             case '\\':
 180               ch = scan(sc);
 181               if (ch == EOF)
 182                 goto word;
 183               DPUTC(&sc->d, ch);
 184               break;
 185             case '\"':
 186               q = !q;
 187               break;
 188             case SELFDELIM:
 189               if (q || (notdelim && strchr(notdelim, ch)))
 190                 goto insert;
 191               goto word;
 192             default:
 193               if (!q && isspace(ch))
 194                 goto word;
 195             insert:
 196               DPUTC(&sc->d, ch);
 197               break;
 198           }
 199           ch = scan(sc);
 200         }
 201       word:
 202         unscan(sc, ch);
 203         DPUTZ(&sc->d);
 204         sc->t = CTOK_WORD;
 205         goto done;
 206       }
 207     }
 208   }
 209
 210 done:
 211   return (sc->t);
 212 }
 213
 214 /* --- @pushback@ --- *
 215  *
 216  * Arguments:   @scanner *sc@ = pointer to scanner definition
 217  *
 218  * Returns:     ---
 219  *
 220  * Use:         Pushes the current token back.  This is normally a precursor
 221  *              to pushing a new scanner source.
 222  */
 223
 224 static void pushback(scanner *sc)
 225 {
 226   sc->head->tok = xstrdup(sc->d.buf);
 227   sc->head->t = sc->t;
 228 }
 229
 230 /* --- @error@ --- *
 231  *
 232  * Arguments:   @scanner *sc@ = pointer to scanner definition
 233  *              @const char *msg@ = message skeleton string
 234  *              @...@ = extra arguments for the skeleton
 235  *
 236  * Returns:     Doesn't
 237  *
 238  * Use:         Reports an error at the current scanner location.
 239  */
 240
 241 void error(scanner *sc, const char *msg, ...)
 242 {
 243   va_list ap;
 244   va_start(ap, msg);
 245   fprintf(stderr, "%s: %s:%i: ", QUIS, sc->head->src, sc->head->line);
 246   vfprintf(stderr, msg, ap);
 247   fputc('\n', stderr);
 248   exit(1);
 249 }
 250
 251 /* --- @conf_enum@ --- *
 252  *
 253  * Arguments:   @scanner *sc@ = pointer to a scanner object
 254  *              @const char *list@ = comma-separated things to allow
 255  *              @unsigned f@ = flags for the search
 256  *              @const char *err@ = error message if not found
 257  *
 258  * Returns:     Index into list, zero-based, or @-1@.
 259  *
 260  * Use:         Checks whether the current token is a string which matches
 261  *              one of the comma-separated items given.  The return value is
 262  *              the index (zero-based) of the matched string in the list.
 263  *
 264  *              The flags control the behaviour if no exact match is found.
 265  *              If @ENUM_ABBREV@ is set, and the current token is a left
 266  *              substring of exactly one of the possibilities, then that one
 267  *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 268  *              returned; otherwise an error is reported and the program is
 269  *              terminated.
 270  */
 271
 272 int conf_enum(scanner *sc, const char *list, unsigned f, const char *err)
 273 {
 274   const char *p, *q;
 275   int chosen = -1;
 276   int ok;
 277   int index;
 278
 279   /* --- Make sure it's a string --- */
 280
 281   if (sc->t != CTOK_WORD)
 282     error(sc, "parse error, expected %s", err);
 283
 284   /* --- Grind through the list --- */
 285
 286   q = sc->d.buf;
 287   ok = 1;
 288   index = 0;
 289   p = list;
 290   for (;;) {
 291     switch (*p) {
 292       case 0:
 293         if (ok && !*q) {
 294           token(sc);
 295           return (index);
 296         } else if (chosen != -1) {
 297           token(sc);
 298           return (chosen);
 299         }
 300         else if (f & ENUM_NONE)
 301           return (-1);
 302         else
 303           error(sc, "unknown %s `%s'", err, sc->d.buf);
 304         break;
 305       case ',':
 306         if (ok && !*q) {
 307           token(sc);
 308           return (index);
 309         }
 310         ok = 1;
 311         q = sc->d.buf;
 312         index++;
 313         break;
 314       default:
 315         if (!ok)
 316           break;
 317         if ((f & ENUM_ABBREV) && !*q) {
 318           if (chosen != -1)
 319             error(sc, "ambiguous %s `%s'", err, sc->d.buf);
 320           chosen = index;
 321           ok = 0;
 322         }
 323         if (*p == *q)
 324           q++;
 325         else
 326           ok = 0;
 327         break;
 328     }
 329     p++;
 330   }
 331 }
 332
 333 /* --- @conf_prefix@ --- *
 334  *
 335  * Arguments:   @scanner *sc@ = pointer to a scanner object
 336  *              @const char *p@ = pointer to prefix string to check
 337  *
 338  * Returns:     Nonzero if the prefix matches.
 339  *
 340  * Use:         If the current token is a word matching the given prefix
 341  *              string, then it and an optional `.' character are removed and
 342  *              a nonzero result is returned.  Otherwise the current token is
 343  *              left as it is, and zero is returned.
 344  *
 345  *              Typical options parsing code would remove an expected prefix,
 346  *              scan an option anyway (since qualifying prefixes are
 347  *              optional) and if a match is found, claim the option.  If no
 348  *              match is found, and a prefix was stripped, then an error
 349  *              should be reported.
 350  */
 351
 352 int conf_prefix(scanner *sc, const char *p)
 353 {
 354   if (sc->t == CTOK_WORD && strcmp(p, sc->d.buf) == 0) {
 355     token(sc);
 356     if (sc->t == '.')
 357       token(sc);
 358     return (1);
 359   }
 360   return (0);
 361 }
 362
 363 /* --- @conf_name@ --- *
 364  *
 365  * Arguments:   @scanner *sc@ = pointer to scanner
 366  *              @char delim@ = delimiter character to look for
 367  *              @dstr *d@ = pointer to dynamic string for output
 368  *
 369  * Returns:     ---
 370  *
 371  * Use:         Reads in a compound name consisting of words separated by
 372  *              delimiters.  Leading and trailing delimiters are permitted,
 373  *              although they'll probably cause confusion if used.  The name
 374  *              may be enclosed in square brackets if that helps at all.
 375  *
 376  *              Examples of compound names are filenames (delimited by `/')
 377  *              and IP addresses (delimited by `.').
 378  */
 379
 380 void conf_name(scanner *sc, char delim, dstr *d)
 381 {
 382   unsigned f = 0;
 383   enum {
 384     f_ok = 1,
 385     f_bra = 2
 386   };
 387
 388   /* --- Read an optional opening bracket --- */
 389
 390   if (sc->t == '[') {
 391     token(sc);
 392     f |= f_bra;
 393   }
 394
 395   /* --- Do the main reading sequence --- */
 396
 397   do {
 398     if (sc->t == delim) {
 399       DPUTC(d, delim);
 400       f |= f_ok;
 401       token(sc);
 402     }
 403     if (sc->t == CTOK_WORD) {
 404       DPUTD(d, &sc->d);
 405       f |= f_ok;
 406       token(sc);
 407     }
 408   } while (sc->t == delim);
 409
 410   /* --- Check that the string was OK --- */
 411
 412   if (!(f & f_ok))
 413     error(sc, "parse error, name expected");
 414
 415   /* --- Read a closing bracket --- */
 416
 417   if (f & f_bra) {
 418     if (sc->t == ']')
 419       token(sc);
 420     else
 421       error(sc, "parse error, missing `]'");
 422   }
 423   DPUTZ(d);
 424 }
 425
 426 /* --- @conf_parse@ --- *
 427  *
 428  * Arguments:   @scanner *sc@ = pointer to scanner definition
 429  *
 430  * Returns:     ---
 431  *
 432  * Use:         Parses a configuration file from the scanner.
 433  */
 434
 435 void conf_parse(scanner *sc)
 436 {
 437   token(sc);
 438
 439   for (;;) {
 440     if (sc->t == CTOK_EOF)
 441       break;
 442     if (sc->t != CTOK_WORD)
 443       error(sc, "parse error, keyword expected");
 444
 445     /* --- Handle a forwarding request --- */
 446
 447     if (strcmp(sc->d.buf, "forward") == 0 ||
 448         strcmp(sc->d.buf, "fw") == 0 ||
 449         strcmp(sc->d.buf, "from") == 0) {
 450       source *s;
 451       target *t;
 452
 453       token(sc);
 454
 455       /* --- Read a source description --- */
 456
 457       {
 458         source_ops **sops;
 459
 460         /* --- Try to find a source type which understands --- */
 461
 462         s = 0;
 463         for (sops = sources; *sops; sops++) {
 464           if ((s = (*sops)->read(sc)) != 0)
 465             goto found_source;
 466         }
 467         error(sc, "unknown source name `%s'", sc->d.buf);
 468
 469         /* --- Read any source-specific options --- */
 470
 471       found_source:
 472         if (sc->t == '{') {
 473           token(sc);
 474           while (sc->t == CTOK_WORD) {
 475             if (!s->ops->option || !s->ops->option(s, sc)) {
 476               error(sc, "unknown %s source option `%s'",
 477                     s->ops->name, sc->d.buf);
 478             }
 479             if (sc->t == ';')
 480               token(sc);
 481           }
 482           if (sc->t != '}')
 483             error(sc, "parse error, missing `}'");
 484           token(sc);
 485         }
 486       }
 487
 488       /* --- Read a destination description --- */
 489
 490       if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "to") == 0 ||
 491                                  strcmp(sc->d.buf, "->") == 0))
 492         token(sc);
 493
 494       {
 495         target_ops **tops;
 496
 497         /* --- Try to find a target which understands --- */
 498
 499         t = 0;
 500         for (tops = targets; *tops; tops++) {
 501           if ((t = (*tops)->read(sc)) != 0)
 502             goto found_target;
 503         }
 504         error(sc, "unknown target name `%s'", sc->d.buf);
 505
 506         /* --- Read any target-specific options --- */
 507
 508       found_target:
 509         if (sc->t == '{') {
 510           token(sc);
 511           while (sc->t == CTOK_WORD) {
 512             if (!t->ops->option || !t->ops->option(t, sc)) {
 513               error(sc, "unknown %s target option `%s'",
 514                     t->ops->name, sc->d.buf);
 515             }
 516             if (sc->t == ';')
 517               token(sc);
 518           }
 519           if (sc->t != '}')
 520             error(sc, "parse error, `}' expected");
 521           token(sc);
 522         }
 523       }
 524
 525       /* --- Combine the source and target --- */
 526
 527       s->ops->attach(s, sc, t);
 528     }
 529
 530     /* --- Include configuration from a file --- *
 531      *
 532      * Slightly tricky.  Scan the optional semicolon from the including
 533      * stream, not the included one.
 534      */
 535
 536     else if (strcmp(sc->d.buf, "include") == 0) {
 537       FILE *fp;
 538       dstr d = DSTR_INIT;
 539
 540       token(sc);
 541       conf_name(sc, '/', &d);
 542       if ((fp = fopen(d.buf, "r")) == 0)
 543         error(sc, "can't include `%s': %s", d.buf, strerror(errno));
 544       if (sc->t == ';')
 545         token(sc);
 546       pushback(sc);
 547       scan_push(sc, scan_file(fp, xstrdup(d.buf), SCF_FREENAME));
 548       token(sc);
 549       dstr_destroy(&d);
 550       continue;                         /* Don't parse a trailing `;' */
 551     }
 552
 553     /* --- Other configuration is handled elsewhere --- */
 554
 555     else {
 556
 557       /* --- First try among the sources --- */
 558
 559       {
 560         source_ops **sops;
 561
 562         for (sops = sources; *sops; sops++) {
 563           if ((*sops)->option && (*sops)->option(0, sc))
 564             goto found_option;
 565         }
 566       }
 567
 568       /* --- Then try among the targets --- */
 569
 570       {
 571         target_ops **tops;
 572
 573         for (tops = targets; *tops; tops++) {
 574           if ((*tops)->option && (*tops)->option(0, sc))
 575             goto found_option;
 576         }
 577       }
 578
 579       /* --- Nobody wants the option --- */
 580
 581       error(sc, "unknown global option or prefix `%s'", sc->d.buf);
 582
 583     found_option:;
 584     }
 585
 586     if (sc->t == ';')
 587       token(sc);
 588   }
 589 }
 590
 591 /*----- That's all, folks -------------------------------------------------*/