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

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