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

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