mdw@git.distorted.org.uk Git - become/blob - src/netg.c

   1 /* -*-c-*-
   2  *
   3  * $Id: netg.c,v 1.7 2004/04/08 01:36:20 mdw Exp $
   4  *
   5  * A local database of netgroups
   6  *
   7  * (c) 1998 EBI
   8  */
   9
  10 /*----- Licensing notice --------------------------------------------------*
  11  *
  12  * This file is part of `become'
  13  *
  14  * `Become' 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  * `Become' 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 `become'; if not, write to the Free Software Foundation,
  26  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  27  */
  28
  29 /*----- Header files ------------------------------------------------------*/
  30
  31 /* --- ANSI headers --- */
  32
  33 #include <ctype.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37
  38 /* --- Unix headers --- */
  39
  40 #include "config.h"
  41
  42 #include <sys/types.h>
  43
  44 #include <netinet/in.h>
  45
  46 #include <arpa/inet.h>
  47
  48 #include <pwd.h>
  49 #include <netdb.h>
  50 #include <unistd.h>
  51
  52 /* --- mLib headers --- */
  53
  54 #include <mLib/alloc.h>
  55 #include <mLib/report.h>
  56 #include <mLib/sym.h>
  57 #include <mLib/trace.h>
  58
  59 /* --- Local headers --- */
  60
  61 #include "become.h"
  62 #include "config.h"
  63 #include "netg.h"
  64 #include "userdb.h"
  65 #include "ypstuff.h"
  66
  67 /*----- Type definitions --------------------------------------------------*/
  68
  69 /* --- Quick discussion --- *
  70  *
  71  * I've just noticed: netgroups are horrible.  They form a directed graph
  72  * which is really horrible; I'll have to try and turn it into something
  73  * more sensible (which will essentially involve cutting cycles).
  74  *
  75  * The structure looks a little bit like a good ol' List (see Knuth 1 or
  76  * any decent Lisp manual), but with more information in the cons cells.
  77  */
  78
  79 /* --- @netg__cons@ --- */
  80
  81 typedef struct netg__cons {
  82   unsigned f;
  83   union {
  84     struct netg__cons *cons;
  85     struct netg__atom *atom;
  86   } car;
  87   struct netg__cons *cdr;
  88 } netg__cons;
  89
  90 enum {
  91   f_cons = 1,                           /* The @car@ is a cons cell */
  92   f_visit = 2,                          /* Currently threaded on this cell */
  93   f_uncycled = 4                        /* Cycles removed from here on in */
  94 };
  95
  96 /* --- @netg__atom@ --- */
  97
  98 typedef struct netg__atom {
  99   char *n;                              /* Unresolved netgroup reference */
 100   char *h;                              /* Matched hostname */
 101   char *u;                              /* Matched user name */
 102   char *d;                              /* Matched domain name */
 103 } netg__atom;
 104
 105 /* --- @netg__sym@ --- */
 106
 107 typedef struct netg__sym {
 108   sym_base _base;
 109   netg__cons *cons;
 110 } netg__sym;
 111
 112 /* --- Token types for the netgroup parser --- */
 113
 114 enum {
 115   tok_string = 256,
 116   tok_eof
 117 };
 118
 119 /*----- Static variables --------------------------------------------------*/
 120
 121 static sym_table netg__table;           /* Netgroup table */
 122 static sym_iter netg__iter;             /* Iterator object for users */
 123
 124 /*----- Main code ---------------------------------------------------------*/
 125
 126 /* --- @netg__lex@ --- *
 127  *
 128  * Arguments:   @const char **p@ = pointer to next unscanned character
 129  *              @char *q@ = pointer to output buffer
 130  *
 131  * Returns:     Token type (either character code or a magic number).
 132  *
 133  * Use:         Lexes a netgroups line into tokens.
 134  */
 135
 136 static int netg__lex(char **p, char *q)
 137 {
 138   /* --- Skip any leading whitespace --- */
 139
 140   while (isspace((unsigned char)**p))
 141     (*p)++;
 142
 143   /* --- Now work out what we've got --- */
 144
 145   if (**p == 0)
 146     return (tok_eof);
 147   if (**p == '(' || **p == ')' || **p == ',')
 148     return (*(*p)++);
 149   do
 150     *q++ = *(*p)++;
 151   while (**p != 0 && **p != '(' && **p != ')' &&
 152          **p != ',' && !isspace((unsigned char)**p));
 153   *q++ = 0;
 154   return (tok_string);
 155 }
 156
 157 /* --- @netg__foreach@ --- *
 158  *
 159  * Arguments:   @int st@ = YP protocol-level status code
 160  *              @char *k@ = pointer to string containing the key
 161  *              @int ksz@ = length of the key string
 162  *              @char *v@ = pointer to string containing the value
 163  *              @int vsz@ = length of the value string
 164  *              @char *data@ = pointer to my data information
 165  *
 166  * Returns:     Zero to continue, nonzero for no more entries.
 167  *
 168  * Use:         Handles each incoming netgroup, attaching it to the table.
 169  */
 170
 171 static int netg__foreach(int st, char *k, int ksz,
 172                          char *v, int vsz, char *data)
 173 {
 174   char *kc, *vc;
 175   unsigned f;
 176   netg__sym *sng;
 177   netg__cons *c, **link;
 178   char *p;
 179   int t;
 180
 181   /* --- If something is amiss, then quit now --- */
 182
 183   if (st != YP_TRUE)
 184     return (-1);
 185
 186   /* --- Ignore empty lines from the original file --- */
 187
 188   if (!ksz || !vsz)
 189     return (0);
 190
 191   /* --- Build my own trashable copies of the key and value --- *
 192    *
 193    * Note the oddness when I copy the value string.  The extra byte at the
 194    * beginning allows me to use the same area of memory as an output buffer
 195    * for the lexer.  It must be big enough; the lexer doesn't back up; and
 196    * that extra byte gives me somewhere to put a terminating null byte.
 197    */
 198
 199   kc = xmalloc(ksz + 1);
 200   memcpy(kc, k, ksz);
 201   kc[ksz] = 0;
 202
 203   vc = xmalloc(vsz + 2);
 204   memcpy(vc + 1, v, vsz);
 205   vc[vsz + 1] = 0;
 206
 207   T( trace(TRACE_DEBUG, "debug: netgroup `%s': `%s'", kc, vc + 1); )
 208
 209   /* --- Allocate a symbol in my table --- */
 210
 211   sng = sym_find(&netg__table, kc, -1, sizeof(*sng), &f);
 212   if (!f)
 213     sng->cons = 0;
 214
 215   /* --- Run to the end of the list --- */
 216
 217   for (link = &sng->cons; *link; link = &((*link)->cdr))
 218     ;
 219
 220   /* --- Now start the tricky bit --- *
 221    *
 222    * I have to start parsing the netgroup value string.  Oh, well, it
 223    * could be worse.
 224    *
 225    * The parser is written so as to avoid saying things more often than
 226    * necessary.  This tends to involve @goto@s.  You've been warned.
 227    */
 228
 229   p = vc + 1;
 230   t = netg__lex(&p, vc);
 231
 232   for (;;) {
 233
 234     /* --- Start with a fresh cons cell, with an empty atom attached --- */
 235
 236     c = xmalloc(sizeof(*c));
 237     c->car.atom = xmalloc(sizeof(*c->car.atom));
 238
 239     /* --- Restart here after an error --- *
 240      *
 241      * If I restart here, I can avoid freeing the cons cell reallocating
 242      * it, which is a little silly.
 243      */
 244
 245   duff_restart:
 246     c->car.atom->n = c->car.atom->h = c->car.atom->u = c->car.atom->d = 0;
 247     c->f = 0;
 248     c->cdr = 0;
 249
 250     /* --- Handle end-of-line --- */
 251
 252     if (t == tok_eof)
 253       break;
 254
 255     /* --- Handle a netgroup reference --- */
 256
 257     if (t == tok_string) {
 258       T( trace(TRACE_DEBUG, "debug: add reference to `%s'", vc); )
 259       c->car.atom->n = xstrdup(vc);
 260       *link = c;
 261       link = &c->cdr;
 262       t = netg__lex(&p, vc);
 263       continue;
 264     }
 265
 266     /* --- Parse our merry way through the host--user--domain triple --- */
 267
 268     if (t != '(')
 269       goto duff;
 270     t = netg__lex(&p, vc);
 271
 272     if (t == tok_string) {
 273       T( trace(TRACE_DEBUG, "debug: add host `%s'", vc); )
 274       c->car.atom->h = xstrdup(vc);
 275       t = netg__lex(&p, vc);
 276     }
 277
 278     if (t != ',')
 279       goto duff_paren;
 280     t = netg__lex(&p, vc);
 281
 282     if (t == tok_string) {
 283       T( trace(TRACE_DEBUG, "debug: add user `%s'", vc); )
 284       c->car.atom->u = xstrdup(vc);
 285       t = netg__lex(&p, vc);
 286     }
 287
 288     if (t != ',')
 289       goto duff_paren;
 290     t = netg__lex(&p, vc);
 291
 292     if (t == tok_string) {
 293       T( trace(TRACE_DEBUG, "debug: add domain `%s'", vc); )
 294       c->car.atom->d = xstrdup(vc);
 295       t = netg__lex(&p, vc);
 296     }
 297
 298     if (t != ')')
 299       goto duff_paren;
 300     t = netg__lex(&p, vc);
 301
 302     /* --- Finished that, so insert this cons cell into the list --- */
 303
 304     *link = c;
 305     link = &c->cdr;
 306     continue;
 307
 308     /* --- Tidy up during scanning of a triple --- *
 309      *
 310      * I'll search for the closing paren, and hope that I won't miss out too
 311      * much.
 312      */
 313
 314   duff_paren:
 315     while (t != tok_eof && t != ')')
 316       t = netg__lex(&p, vc);
 317
 318     /* --- Other syntax oddnesses come out here --- *
 319      *
 320      * Snarf the token which caused the error.
 321      */
 322
 323   duff:
 324     moan("syntax error in netgroups line for `%s'", kc);
 325     if (c->car.atom->n) free(c->car.atom->n);
 326     if (c->car.atom->h) free(c->car.atom->h);
 327     if (c->car.atom->u) free(c->car.atom->u);
 328     if (c->car.atom->d) free(c->car.atom->d);
 329     t = netg__lex(&p, vc);
 330     goto duff_restart;
 331   }
 332
 333   free(c->car.atom);
 334   free(c);
 335   free(kc);
 336   free(vc);
 337   return (0);
 338 }
 339
 340 /* --- @netg__dumpGroup@ ---  *
 341  *
 342  * Arguments:   @netg__cons *c@ = pointer to a list head
 343  *              @int lev@ = indentation level
 344  *
 345  * Returns:     ---
 346  *
 347  * Use:         Dumps the netgroup given.
 348  */
 349
 350 #ifndef NTRACE
 351
 352 static void netg__dumpGroup(netg__cons *c, int lev)
 353 {
 354   netg__cons *cc;
 355
 356   if (!c)
 357     return;
 358
 359   /* --- Check for a cycle --- */
 360
 361   if (c->f & f_visit) {
 362     trace(TRACE_DEBUG, "debug: %*scycle!", lev * 2, "");
 363     return;
 364   }
 365
 366   /* --- Dump the netgroup --- */
 367
 368   c->f |= f_visit;
 369
 370   for (cc = c; cc; cc = cc->cdr) {
 371     if (cc->f & f_cons) {
 372       trace(TRACE_DEBUG, "debug: %*ssubnetgroup...", lev * 2, "");
 373       netg__dumpGroup(cc->car.cons, lev + 1);
 374     } else if (cc->car.atom->n) {
 375       trace(TRACE_DEBUG, "debug: %*sunresolved subgroup `%s'",
 376             lev * 2, "", cc->car.atom->n);
 377     } else {
 378       trace(TRACE_DEBUG, "debug: %*s(%s, %s, %s)", lev * 2, "",
 379             cc->car.atom->h ? cc->car.atom->h : "<all-hosts>",
 380             cc->car.atom->u ? cc->car.atom->u : "<all-users>",
 381             cc->car.atom->d ? cc->car.atom->d : "<all-domains>");
 382     }
 383   }
 384
 385   c->f &= ~f_visit;
 386 }
 387
 388 #endif
 389
 390 /* --- @netg__dump@ --- *
 391  *
 392  * Arguments:   ---
 393  *
 394  * Returns:     ---
 395  *
 396  * Use:         Dumps the netgroups table.
 397  */
 398
 399 #ifndef NTRACE
 400
 401 static void netg__dump(void)
 402 {
 403   sym_iter i;
 404   netg__sym *sng;
 405
 406   trace(TRACE_DEBUG, "debug: dumping netgroups file");
 407   for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 408     trace(TRACE_DEBUG, "debug: netgroup `%s'...", sng->_base.name);
 409     sng->cons->f &= ~f_visit;
 410     netg__dumpGroup(sng->cons, 1);
 411   }
 412 }
 413
 414 #endif
 415
 416 /* --- @netg_iterate@, @netg_iterate_r@ --- *
 417  *
 418  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 419  *
 420  * Returns:     ---
 421  *
 422  * Use:         Starts iterating over the netgroups.
 423  */
 424
 425 void netg_iterate(void) { netg_iterate_r(&netg__iter); }
 426 void netg_iterate_r(netg_iter *i) { sym_mkiter(i, &netg__table); }
 427
 428 /* --- @netg_next@, @netg_next_r@ --- *
 429  *
 430  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 431  *
 432  * Returns:     An opaque pointer to the next item, or null.
 433  *
 434  * Use:         Returns the next netgroup.
 435  */
 436
 437 netg *netg_next(void) { return (netg_next_r(&netg__iter)); }
 438 netg *netg_next_r(netg_iter *i) { return (sym_next(i)); }
 439
 440 /* --- @netg_name@ --- *
 441  *
 442  * Arguments:   @netg *n@ = netgroup handle returned by @netg_next@.
 443  *
 444  * Returns:     A pointer to the name; you may not modify this string.
 445  *
 446  * Use:         Returns the name of a netgroup.
 447  */
 448
 449 const char *netg_name(netg *n) { return (n->_base.name); }
 450
 451 /* --- @netg_scan@ --- *
 452  *
 453  * Arguments:   @netg *n@ = a netgroup handle returned by @netg_next@
 454  *              @int (*proc)(netg *n, const char *host, const char *user,@
 455  *                      @const char *domain, void *ctx)@ = function to call
 456  *                              for each member.
 457  *              @void *ctx@ = context pointer to pass to @proc@.
 458  *
 459  * Returns:     Zero if all went well, or the nonzero return value from
 460  *              @proc@.
 461  *
 462  * Use:         Passes all the members of the netgroup to a given function.
 463  *              The function is given the names, directly from the NIS
 464  *              netgroup map, except that any empty entries are passed as
 465  *              null pointers rather than empty strings.  You may not modify
 466  *              any of the strings.  The enumeration function, @proc@, may
 467  *              return nonzero to stop itself from being called any more;
 468  *              if this happens, the value it returns becomes the result of
 469  *              this function.  If all the items are enumerated OK, this
 470  *              function returns zero.
 471  */
 472
 473 static int netg__doScan(netg__cons *c,
 474                         netg *n,
 475                         int (*proc)(netg */*n*/, const char */*host*/,
 476                                     const char */*user*/,
 477                                     const char */*domain*/, void */*ctx*/),
 478                         void *ctx)
 479 {
 480   int e;
 481
 482   while (c) {
 483     if (c->f & f_cons)
 484       e = netg__doScan(c->car.cons, n, proc, ctx);
 485     else
 486       e = proc(n, c->car.atom->h, c->car.atom->u, c->car.atom->d, ctx);
 487     if (e)
 488       return (e);
 489     c = c->cdr;
 490   }
 491   return (0);
 492 }
 493
 494 int netg_scan(netg *n,
 495               int (*proc)(netg */*n*/, const char */*host*/,
 496                           const char */*user*/, const char */*domain*/,
 497                           void */*ctx*/),
 498               void *ctx)
 499 {
 500   return (netg__doScan(n->cons, n, proc, ctx));
 501 }
 502
 503 /* --- @netg__breakCycle@ --- *
 504  *
 505  * Arguments:   @netg__cons *c@ = pointer to a list
 506  *
 507  * Returns:     ---
 508  *
 509  * Use:         Scans the given list (recursively) and breaks any cycles it
 510  *              finds.
 511  */
 512
 513 static void netg__breakCycle(netg__cons *c)
 514 {
 515   netg__cons *cc;
 516
 517   if (!c || c->f & f_uncycled)
 518     return;
 519
 520   c->f |= f_visit;
 521   for (cc = c; cc; cc = cc->cdr) {
 522     if (~cc->f & f_cons)
 523       continue;
 524     if (cc->car.cons->f & f_visit) {
 525       T( trace(TRACE_DEBUG, "debug: cycle in netgroups"); )
 526       cc->car.cons = 0;
 527     } else
 528       netg__breakCycle(cc->car.cons);
 529   }
 530   c->f &= ~f_visit;
 531   c->f |= f_uncycled;
 532 }
 533
 534 /* --- @netg_init@ --- *
 535  *
 536  * Arguments:   ---
 537  *
 538  * Returns:     ---
 539  *
 540  * Use:         Reads the netgroup database and turns it into something nice.
 541  */
 542
 543 void netg_init(void)
 544 {
 545   /* --- Initialise my symbol table --- */
 546
 547   sym_create(&netg__table);
 548
 549   /* --- Bind myself unto a YP server --- */
 550
 551   ypstuff_bind();
 552   if (!yp_domain)
 553     return;
 554
 555   /* --- Now try to read all the netgroup entries --- */
 556
 557   {
 558     static struct ypall_callback ncb = { netg__foreach, 0 };
 559     yp_all(yp_domain, "netgroup", &ncb);
 560   }
 561
 562   /* --- Dump the table --- */
 563
 564   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 565
 566   /* --- Now resolve all the remaining references --- */
 567
 568   {
 569     sym_iter i;
 570     netg__sym *sng, *ng;
 571     netg__cons *c;
 572     netg__atom *a;
 573
 574     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 575       for (c = sng->cons; c; c = c->cdr) {
 576         if ((c->f & f_cons) == 0 && c->car.atom->n) {
 577           a = c->car.atom;
 578           ng = sym_find(&netg__table, a->n, -1, 0, 0);
 579           if (!ng) {
 580             moan("undefined netgroup `%s' (ignored)", a->n);
 581             c->car.atom = 0;
 582           } else {
 583             c->car.cons = ng->cons;
 584             c->f |= f_cons;
 585           }
 586           free(a->n);
 587           free(a);
 588         }
 589       }
 590     }
 591   }
 592
 593   /* --- Remove cycles in the netgroups table --- */
 594
 595   {
 596     sym_iter i;
 597     netg__sym *sng;
 598
 599     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 600       sng->cons->f &= ~f_uncycled;
 601     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 602       netg__breakCycle(sng->cons);
 603   }
 604
 605   /* --- Dump the table again --- */
 606
 607   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 608 }
 609
 610 /* --- @netg_end@ --- *
 611  *
 612  * Arguments:   ---
 613  *
 614  * Returns:     ---
 615  *
 616  * Use:         Empties the netgroups database.
 617  */
 618
 619 void netg_end(void)
 620 {
 621   sym_iter i;
 622   netg__sym *sng;
 623   netg__cons *c, *cc;
 624
 625   /* --- Remove all the old netgroups rubbish --- */
 626
 627   for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 628     c = sng->cons;
 629     while (c) {
 630       cc = c->cdr;
 631       if (~c->f & f_cons) {
 632         if (c->car.atom->n) free(c->car.atom->n);
 633         if (c->car.atom->h) free(c->car.atom->h);
 634         if (c->car.atom->u) free(c->car.atom->u);
 635         if (c->car.atom->d) free(c->car.atom->d);
 636         free(c->car.atom);
 637       }
 638       free(c);
 639       c = cc;
 640     }
 641     sym_remove(&netg__table, sng);
 642   }
 643
 644   sym_destroy(&netg__table);
 645 }
 646
 647 /*----- Test driver -------------------------------------------------------*/
 648
 649 #ifdef TEST_RIG
 650
 651 int scanner(netg *n, const char *h, const char *u, const char *d, void *c)
 652 {
 653   fprintf(stderr, "  %s, %s, %s\n",
 654           h ? h : "<any>", u ? u : "<any>", d ? d : "<any>");
 655   return (0);
 656 }
 657
 658 int main(void)
 659 {
 660   netg *n;
 661   ego("netg-test");
 662   trace_on(stderr, TRACE_ALL);
 663   netg_init();
 664   for (netg_iterate(); (n = netg_next()) != 0; ) {
 665     fprintf(stderr, "netgroup %s\n", netg_name(n));
 666     netg_scan(n, scanner, 0);
 667   }
 668   return (0);
 669 }
 670
 671 #endif
 672
 673 /*----- That's all, folks -------------------------------------------------*/