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

   1 /* -*-c-*-
   2  *
   3  * $Id: conf.c,v 1.9 2002/01/13 14:48:16 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 1.9  2002/01/13 14:48:16  mdw
  33  * Make delimiters be a property of a scanner.  Change the delimiter-
  34  * changing functions' names.
  35  *
  36  * Revision 1.8  2001/02/03 20:33:26  mdw
  37  * Fix flags to be unsigned.
  38  *
  39  * Revision 1.7  2000/08/01 17:58:10  mdw
  40  * Fix subtleties with <ctype.h> functions.
  41  *
  42  * Revision 1.6  2000/02/12 18:13:20  mdw
  43  * Terminate tables of sources and targets.
  44  *
  45  * Revision 1.5  1999/10/22 22:46:44  mdw
  46  * Improve documentation for conf_enum.
  47  *
  48  * Revision 1.4  1999/10/15 21:12:36  mdw
  49  * Remove redundant debugging code.
  50  *
  51  * Revision 1.3  1999/08/19 18:32:48  mdw
  52  * Improve lexical analysis.  In particular, `chmod' patterns don't have to
  53  * be quoted any more.
  54  *
  55  * Revision 1.2  1999/07/26 23:28:39  mdw
  56  * Major reconstruction work for new design.
  57  *
  58  * Revision 1.1.1.1  1999/07/01 08:56:23  mdw
  59  * Initial revision.
  60  *
  61  */
  62
  63 /*----- Header files ------------------------------------------------------*/
  64
  65 #include "config.h"
  66
  67 #include <ctype.h>
  68 #include <errno.h>
  69 #include <stdarg.h>
  70 #include <stdio.h>
  71 #include <stdlib.h>
  72 #include <string.h>
  73
  74 #include <mLib/dstr.h>
  75 #include <mLib/quis.h>
  76 #include <mLib/report.h>
  77
  78 #include "conf.h"
  79 #include "scan.h"
  80 #include "source.h"
  81 #include "target.h"
  82
  83 #include "exec.h"
  84 #include "file.h"
  85 #include "socket.h"
  86
  87 /*----- Source and target tables ------------------------------------------*/
  88
  89 static source_ops *sources[] =
  90   { &xsource_ops, &fsource_ops, &ssource_ops, 0 };
  91 static target_ops *targets[] =
  92   { &xtarget_ops, &ftarget_ops, &starget_ops, 0 };
  93
  94 /*----- Main code ---------------------------------------------------------*/
  95
  96 /* --- @conf_undelim@ --- *
  97  *
  98  * Arguments:   @scanner *sc@ = pointer to scanner definition
  99  *              @const char *d, *dd@ = pointer to characters to escape
 100  *
 101  * Returns:     ---
 102  *
 103  * Use:         Modifies the tokenizer.  Characters in the first list will
 104  *              always be considered to begin a word.  Characters in the
 105  *              second list will always be allowed to continue a word.
 106  */
 107
 108 void conf_undelim(scanner *sc, const char *d, const char *dd)
 109 {
 110   sc->wbegin = d;
 111   sc->wcont = dd;
 112 }
 113
 114 /* --- @token@ --- *
 115  *
 116  * Arguments:   @scanner *sc@ = pointer to scanner definition
 117  *
 118  * Returns:     Type of token scanned.
 119  *
 120  * Use:         Reads the next token from the character scanner.
 121  */
 122
 123 int token(scanner *sc)
 124 {
 125 #define SELFDELIM \
 126   '{': case '}': case '/': case ',': \
 127   case '=': case ':': case ';': \
 128   case '.': case '[': case ']'
 129
 130   int ch;
 131
 132   DRESET(&sc->d);
 133
 134   /* --- Main tokenization --- */
 135
 136   for (;;) {
 137     ch = scan(sc);
 138
 139     /* --- Deal with pushed-back tokens --- */
 140
 141     if (sc->head->tok) {
 142       dstr_puts(&sc->d, sc->head->tok);
 143       free(sc->head->tok);
 144       sc->head->tok = 0;
 145       sc->t = sc->head->t;
 146       goto done;
 147     }
 148
 149     else if (isspace(ch))
 150       ;
 151     else switch (ch) {
 152
 153       /* --- End of file --- */
 154
 155       case EOF:
 156         sc->t = CTOK_EOF;
 157         goto done;
 158
 159       /* --- Comment character --- */
 160
 161       case '#':
 162         do ch = scan(sc); while (ch != EOF && ch != '\n');
 163         break;
 164
 165       /* --- Various self-delimiting characters --- */
 166
 167       case SELFDELIM:
 168         if (!sc->wbegin || strchr(sc->wbegin, ch) == 0) {
 169           dstr_putc(&sc->d, ch);
 170           dstr_putz(&sc->d);
 171           sc->t = ch;
 172           goto done;
 173         }
 174
 175       /* --- Bare words --- *
 176        *
 177        * These aren't as bare any more.  You can now backslash-escape
 178        * individual characters, and enclose sections in double-quotes.
 179        */
 180
 181       default: {
 182         int q = 0;
 183
 184         for (;;) {
 185           switch (ch) {
 186             case EOF:
 187               goto word;
 188             case '\\':
 189               ch = scan(sc);
 190               if (ch == EOF)
 191                 goto word;
 192               DPUTC(&sc->d, ch);
 193               break;
 194             case '\"':
 195               q = !q;
 196               break;
 197             case SELFDELIM:
 198               if (q || (sc->wcont && strchr(sc->wcont, ch)))
 199                 goto insert;
 200               goto word;
 201             default:
 202               if (!q && isspace(ch))
 203                 goto word;
 204             insert:
 205               DPUTC(&sc->d, ch);
 206               break;
 207           }
 208           ch = scan(sc);
 209         }
 210       word:
 211         unscan(sc, ch);
 212         DPUTZ(&sc->d);
 213         sc->t = CTOK_WORD;
 214         goto done;
 215       }
 216     }
 217   }
 218
 219 done:
 220   return (sc->t);
 221 }
 222
 223 /* --- @pushback@ --- *
 224  *
 225  * Arguments:   @scanner *sc@ = pointer to scanner definition
 226  *
 227  * Returns:     ---
 228  *
 229  * Use:         Pushes the current token back.  This is normally a precursor
 230  *              to pushing a new scanner source.
 231  */
 232
 233 static void pushback(scanner *sc)
 234 {
 235   sc->head->tok = xstrdup(sc->d.buf);
 236   sc->head->t = sc->t;
 237 }
 238
 239 /* --- @error@ --- *
 240  *
 241  * Arguments:   @scanner *sc@ = pointer to scanner definition
 242  *              @const char *msg@ = message skeleton string
 243  *              @...@ = extra arguments for the skeleton
 244  *
 245  * Returns:     Doesn't
 246  *
 247  * Use:         Reports an error at the current scanner location.
 248  */
 249
 250 void error(scanner *sc, const char *msg, ...)
 251 {
 252   va_list ap;
 253   va_start(ap, msg);
 254   fprintf(stderr, "%s: %s:%i: ", QUIS, sc->head->src, sc->head->line);
 255   vfprintf(stderr, msg, ap);
 256   fputc('\n', stderr);
 257   exit(1);
 258 }
 259
 260 /* --- @conf_enum@ --- *
 261  *
 262  * Arguments:   @scanner *sc@ = pointer to a scanner object
 263  *              @const char *list@ = comma-separated things to allow
 264  *              @unsigned f@ = flags for the search
 265  *              @const char *err@ = error message if not found
 266  *
 267  * Returns:     Index into list, zero-based, or @-1@.
 268  *
 269  * Use:         Checks whether the current token is a string which matches
 270  *              one of the comma-separated items given.  The return value is
 271  *              the index (zero-based) of the matched string in the list.
 272  *
 273  *              The flags control the behaviour if no exact match is found.
 274  *              If @ENUM_ABBREV@ is set, and the current token is a left
 275  *              substring of exactly one of the possibilities, then that one
 276  *              is chosen.  If @ENUM_NONE@ is set, the value @-1@ is
 277  *              returned; otherwise an error is reported and the program is
 278  *              terminated.
 279  */
 280
 281 int conf_enum(scanner *sc, const char *list, unsigned f, const char *err)
 282 {
 283   const char *p, *q;
 284   int chosen = -1;
 285   int ok;
 286   int index;
 287
 288   /* --- Make sure it's a string --- */
 289
 290   if (sc->t != CTOK_WORD)
 291     error(sc, "parse error, expected %s", err);
 292
 293   /* --- Grind through the list --- */
 294
 295   q = sc->d.buf;
 296   ok = 1;
 297   index = 0;
 298   p = list;
 299   for (;;) {
 300     switch (*p) {
 301       case 0:
 302         if (ok && !*q) {
 303           token(sc);
 304           return (index);
 305         } else if (chosen != -1) {
 306           token(sc);
 307           return (chosen);
 308         }
 309         else if (f & ENUM_NONE)
 310           return (-1);
 311         else
 312           error(sc, "unknown %s `%s'", err, sc->d.buf);
 313         break;
 314       case ',':
 315         if (ok && !*q) {
 316           token(sc);
 317           return (index);
 318         }
 319         ok = 1;
 320         q = sc->d.buf;
 321         index++;
 322         break;
 323       default:
 324         if (!ok)
 325           break;
 326         if ((f & ENUM_ABBREV) && !*q) {
 327           if (chosen != -1)
 328             error(sc, "ambiguous %s `%s'", err, sc->d.buf);
 329           chosen = index;
 330           ok = 0;
 331         }
 332         if (*p == *q)
 333           q++;
 334         else
 335           ok = 0;
 336         break;
 337     }
 338     p++;
 339   }
 340 }
 341
 342 /* --- @conf_prefix@ --- *
 343  *
 344  * Arguments:   @scanner *sc@ = pointer to a scanner object
 345  *              @const char *p@ = pointer to prefix string to check
 346  *
 347  * Returns:     Nonzero if the prefix matches.
 348  *
 349  * Use:         If the current token is a word matching the given prefix
 350  *              string, then it and an optional `.' character are removed and
 351  *              a nonzero result is returned.  Otherwise the current token is
 352  *              left as it is, and zero is returned.
 353  *
 354  *              Typical options parsing code would remove an expected prefix,
 355  *              scan an option anyway (since qualifying prefixes are
 356  *              optional) and if a match is found, claim the option.  If no
 357  *              match is found, and a prefix was stripped, then an error
 358  *              should be reported.
 359  */
 360
 361 int conf_prefix(scanner *sc, const char *p)
 362 {
 363   if (sc->t == CTOK_WORD && strcmp(p, sc->d.buf) == 0) {
 364     token(sc);
 365     if (sc->t == '.')
 366       token(sc);
 367     return (1);
 368   }
 369   return (0);
 370 }
 371
 372 /* --- @conf_name@ --- *
 373  *
 374  * Arguments:   @scanner *sc@ = pointer to scanner
 375  *              @char delim@ = delimiter character to look for
 376  *              @dstr *d@ = pointer to dynamic string for output
 377  *
 378  * Returns:     ---
 379  *
 380  * Use:         Reads in a compound name consisting of words separated by
 381  *              delimiters.  Leading and trailing delimiters are permitted,
 382  *              although they'll probably cause confusion if used.  The name
 383  *              may be enclosed in square brackets if that helps at all.
 384  *
 385  *              Examples of compound names are filenames (delimited by `/')
 386  *              and IP addresses (delimited by `.').
 387  */
 388
 389 void conf_name(scanner *sc, char delim, dstr *d)
 390 {
 391   unsigned f = 0;
 392
 393 #define f_ok 1u
 394 #define f_bra 2u
 395
 396   /* --- Read an optional opening bracket --- */
 397
 398   if (sc->t == '[') {
 399     token(sc);
 400     f |= f_bra | f_ok;
 401   }
 402
 403   /* --- Do the main reading sequence --- */
 404
 405   do {
 406     if (sc->t == delim) {
 407       DPUTC(d, delim);
 408       f |= f_ok;
 409       token(sc);
 410     }
 411     if (sc->t == CTOK_WORD) {
 412       DPUTD(d, &sc->d);
 413       f |= f_ok;
 414       token(sc);
 415     }
 416   } while (sc->t == delim);
 417
 418   /* --- Check that the string was OK --- */
 419
 420   if (!(f & f_ok))
 421     error(sc, "parse error, name expected");
 422
 423   /* --- Read a closing bracket --- */
 424
 425   if (f & f_bra) {
 426     if (sc->t == ']')
 427       token(sc);
 428     else
 429       error(sc, "parse error, missing `]'");
 430   }
 431   DPUTZ(d);
 432
 433 #undef f_ok
 434 #undef f_bra
 435 }
 436
 437 /* --- @conf_parse@ --- *
 438  *
 439  * Arguments:   @scanner *sc@ = pointer to scanner definition
 440  *
 441  * Returns:     ---
 442  *
 443  * Use:         Parses a configuration file from the scanner.
 444  */
 445
 446 void conf_parse(scanner *sc)
 447 {
 448   token(sc);
 449
 450   for (;;) {
 451     if (sc->t == CTOK_EOF)
 452       break;
 453     if (sc->t != CTOK_WORD)
 454       error(sc, "parse error, keyword expected");
 455
 456     /* --- Handle a forwarding request --- */
 457
 458     if (strcmp(sc->d.buf, "forward") == 0 ||
 459         strcmp(sc->d.buf, "fw") == 0 ||
 460         strcmp(sc->d.buf, "from") == 0) {
 461       source *s;
 462       target *t;
 463
 464       token(sc);
 465
 466       /* --- Read a source description --- */
 467
 468       {
 469         source_ops **sops;
 470
 471         /* --- Try to find a source type which understands --- */
 472
 473         s = 0;
 474         for (sops = sources; *sops; sops++) {
 475           if ((s = (*sops)->read(sc)) != 0)
 476             goto found_source;
 477         }
 478         error(sc, "unknown source name `%s'", sc->d.buf);
 479
 480         /* --- Read any source-specific options --- */
 481
 482       found_source:
 483         if (sc->t == '{') {
 484           token(sc);
 485           while (sc->t == CTOK_WORD) {
 486             if (!s->ops->option || !s->ops->option(s, sc)) {
 487               error(sc, "unknown %s source option `%s'",
 488                     s->ops->name, sc->d.buf);
 489             }
 490             if (sc->t == ';')
 491               token(sc);
 492           }
 493           if (sc->t != '}')
 494             error(sc, "parse error, missing `}'");
 495           token(sc);
 496         }
 497       }
 498
 499       /* --- Read a destination description --- */
 500
 501       if (sc->t == CTOK_WORD && (strcmp(sc->d.buf, "to") == 0 ||
 502                                  strcmp(sc->d.buf, "->") == 0))
 503         token(sc);
 504
 505       {
 506         target_ops **tops;
 507
 508         /* --- Try to find a target which understands --- */
 509
 510         t = 0;
 511         for (tops = targets; *tops; tops++) {
 512           if ((t = (*tops)->read(sc)) != 0)
 513             goto found_target;
 514         }
 515         error(sc, "unknown target name `%s'", sc->d.buf);
 516
 517         /* --- Read any target-specific options --- */
 518
 519       found_target:
 520         if (sc->t == '{') {
 521           token(sc);
 522           while (sc->t == CTOK_WORD) {
 523             if (!t->ops->option || !t->ops->option(t, sc)) {
 524               error(sc, "unknown %s target option `%s'",
 525                     t->ops->name, sc->d.buf);
 526             }
 527             if (sc->t == ';')
 528               token(sc);
 529           }
 530           if (sc->t != '}')
 531             error(sc, "parse error, `}' expected");
 532           token(sc);
 533         }
 534       }
 535
 536       /* --- Combine the source and target --- */
 537
 538       s->ops->attach(s, sc, t);
 539     }
 540
 541     /* --- Include configuration from a file --- *
 542      *
 543      * Slightly tricky.  Scan the optional semicolon from the including
 544      * stream, not the included one.
 545      */
 546
 547     else if (strcmp(sc->d.buf, "include") == 0) {
 548       FILE *fp;
 549       dstr d = DSTR_INIT;
 550
 551       token(sc);
 552       conf_name(sc, '/', &d);
 553       if ((fp = fopen(d.buf, "r")) == 0)
 554         error(sc, "can't include `%s': %s", d.buf, strerror(errno));
 555       if (sc->t == ';')
 556         token(sc);
 557       pushback(sc);
 558       scan_push(sc, scan_file(fp, xstrdup(d.buf), SCF_FREENAME));
 559       token(sc);
 560       dstr_destroy(&d);
 561       continue;                         /* Don't parse a trailing `;' */
 562     }
 563
 564     /* --- Other configuration is handled elsewhere --- */
 565
 566     else {
 567
 568       /* --- First try among the sources --- */
 569
 570       {
 571         source_ops **sops;
 572
 573         for (sops = sources; *sops; sops++) {
 574           if ((*sops)->option && (*sops)->option(0, sc))
 575             goto found_option;
 576         }
 577       }
 578
 579       /* --- Then try among the targets --- */
 580
 581       {
 582         target_ops **tops;
 583
 584         for (tops = targets; *tops; tops++) {
 585           if ((*tops)->option && (*tops)->option(0, sc))
 586             goto found_option;
 587         }
 588       }
 589
 590       /* --- Nobody wants the option --- */
 591
 592       error(sc, "unknown global option or prefix `%s'", sc->d.buf);
 593
 594     found_option:;
 595     }
 596
 597     if (sc->t == ';')
 598       token(sc);
 599   }
 600 }
 601
 602 /*----- That's all, folks -------------------------------------------------*/