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

   1 /* -*-c-*-
   2  *
   3  * $Id: netg.c,v 1.5 2003/10/12 00:14:55 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 /*----- Revision history --------------------------------------------------*
  30  *
  31  * $Log: netg.c,v $
  32  * Revision 1.5  2003/10/12 00:14:55  mdw
  33  * Major overhaul.  Now uses DSA signatures rather than the bogus symmetric
  34  * encrypt-and-hope thing.  Integrated with mLib and Catacomb.
  35  *
  36  * Revision 1.4  1998/04/23 13:24:49  mdw
  37  * Switch to using the ypstuff interface to YP server.
  38  *
  39  * Revision 1.3  1998/01/12 16:46:17  mdw
  40  * Fix copyright date.
  41  *
  42  * Revision 1.2  1997/08/20  16:19:11  mdw
  43  * Patch memory leak.  Replace `name_reinit' by `name_end' for more sensible
  44  * restart.  Don't try to trace when tracing's turned off.
  45  *
  46  * Revision 1.1  1997/08/07 09:45:00  mdw
  47  * New source file added to maintain a netgroups database.
  48  *
  49  */
  50
  51 /*----- Header files ------------------------------------------------------*/
  52
  53 /* --- ANSI headers --- */
  54
  55 #include <ctype.h>
  56 #include <stdio.h>
  57 #include <stdlib.h>
  58 #include <string.h>
  59
  60 /* --- Unix headers --- */
  61
  62 #include "config.h"
  63
  64 #include <sys/types.h>
  65
  66 #include <netinet/in.h>
  67
  68 #include <arpa/inet.h>
  69
  70 #include <pwd.h>
  71 #include <netdb.h>
  72 #include <unistd.h>
  73
  74 /* --- mLib headers --- */
  75
  76 #include <mLib/alloc.h>
  77 #include <mLib/report.h>
  78 #include <mLib/sym.h>
  79 #include <mLib/trace.h>
  80
  81 /* --- Local headers --- */
  82
  83 #include "become.h"
  84 #include "config.h"
  85 #include "netg.h"
  86 #include "userdb.h"
  87 #include "ypstuff.h"
  88
  89 /*----- Type definitions --------------------------------------------------*/
  90
  91 /* --- Quick discussion --- *
  92  *
  93  * I've just noticed: netgroups are horrible.  They form a directed graph
  94  * which is really horrible; I'll have to try and turn it into something
  95  * more sensible (which will essentially involve cutting cycles).
  96  *
  97  * The structure looks a little bit like a good ol' List (see Knuth 1 or
  98  * any decent Lisp manual), but with more information in the cons cells.
  99  */
 100
 101 /* --- @netg__cons@ --- */
 102
 103 typedef struct netg__cons {
 104   unsigned f;
 105   union {
 106     struct netg__cons *cons;
 107     struct netg__atom *atom;
 108   } car;
 109   struct netg__cons *cdr;
 110 } netg__cons;
 111
 112 enum {
 113   f_cons = 1,                           /* The @car@ is a cons cell */
 114   f_visit = 2,                          /* Currently threaded on this cell */
 115   f_uncycled = 4                        /* Cycles removed from here on in */
 116 };
 117
 118 /* --- @netg__atom@ --- */
 119
 120 typedef struct netg__atom {
 121   char *n;                              /* Unresolved netgroup reference */
 122   char *h;                              /* Matched hostname */
 123   char *u;                              /* Matched user name */
 124   char *d;                              /* Matched domain name */
 125 } netg__atom;
 126
 127 /* --- @netg__sym@ --- */
 128
 129 typedef struct netg__sym {
 130   sym_base _base;
 131   netg__cons *cons;
 132 } netg__sym;
 133
 134 /* --- Token types for the netgroup parser --- */
 135
 136 enum {
 137   tok_string = 256,
 138   tok_eof
 139 };
 140
 141 /*----- Static variables --------------------------------------------------*/
 142
 143 static sym_table netg__table;           /* Netgroup table */
 144 static sym_iter netg__iter;             /* Iterator object for users */
 145
 146 /*----- Main code ---------------------------------------------------------*/
 147
 148 /* --- @netg__lex@ --- *
 149  *
 150  * Arguments:   @const char **p@ = pointer to next unscanned character
 151  *              @char *q@ = pointer to output buffer
 152  *
 153  * Returns:     Token type (either character code or a magic number).
 154  *
 155  * Use:         Lexes a netgroups line into tokens.
 156  */
 157
 158 static int netg__lex(char **p, char *q)
 159 {
 160   /* --- Skip any leading whitespace --- */
 161
 162   while (isspace((unsigned char)**p))
 163     (*p)++;
 164
 165   /* --- Now work out what we've got --- */
 166
 167   if (**p == 0)
 168     return (tok_eof);
 169   if (**p == '(' || **p == ')' || **p == ',')
 170     return (*(*p)++);
 171   do
 172     *q++ = *(*p)++;
 173   while (**p != 0 && **p != '(' && **p != ')' &&
 174          **p != ',' && !isspace((unsigned char)**p));
 175   *q++ = 0;
 176   return (tok_string);
 177 }
 178
 179 /* --- @netg__foreach@ --- *
 180  *
 181  * Arguments:   @int st@ = YP protocol-level status code
 182  *              @char *k@ = pointer to string containing the key
 183  *              @int ksz@ = length of the key string
 184  *              @char *v@ = pointer to string containing the value
 185  *              @int vsz@ = length of the value string
 186  *              @char *data@ = pointer to my data information
 187  *
 188  * Returns:     Zero to continue, nonzero for no more entries.
 189  *
 190  * Use:         Handles each incoming netgroup, attaching it to the table.
 191  */
 192
 193 static int netg__foreach(int st, char *k, int ksz,
 194                          char *v, int vsz, char *data)
 195 {
 196   char *kc, *vc;
 197   unsigned f;
 198   netg__sym *sng;
 199   netg__cons *c, **link;
 200   char *p;
 201   int t;
 202
 203   /* --- If something is amiss, then quit now --- */
 204
 205   if (st != YP_TRUE)
 206     return (-1);
 207
 208   /* --- Ignore empty lines from the original file --- */
 209
 210   if (!ksz || !vsz)
 211     return (0);
 212
 213   /* --- Build my own trashable copies of the key and value --- *
 214    *
 215    * Note the oddness when I copy the value string.  The extra byte at the
 216    * beginning allows me to use the same area of memory as an output buffer
 217    * for the lexer.  It must be big enough; the lexer doesn't back up; and
 218    * that extra byte gives me somewhere to put a terminating null byte.
 219    */
 220
 221   kc = xmalloc(ksz + 1);
 222   memcpy(kc, k, ksz);
 223   kc[ksz] = 0;
 224
 225   vc = xmalloc(vsz + 2);
 226   memcpy(vc + 1, v, vsz);
 227   vc[vsz + 1] = 0;
 228
 229   T( trace(TRACE_DEBUG, "debug: netgroup `%s': `%s'", kc, vc + 1); )
 230
 231   /* --- Allocate a symbol in my table --- */
 232
 233   sng = sym_find(&netg__table, kc, -1, sizeof(*sng), &f);
 234   if (!f)
 235     sng->cons = 0;
 236
 237   /* --- Run to the end of the list --- */
 238
 239   for (link = &sng->cons; *link; link = &((*link)->cdr))
 240     ;
 241
 242   /* --- Now start the tricky bit --- *
 243    *
 244    * I have to start parsing the netgroup value string.  Oh, well, it
 245    * could be worse.
 246    *
 247    * The parser is written so as to avoid saying things more often than
 248    * necessary.  This tends to involve @goto@s.  You've been warned.
 249    */
 250
 251   p = vc + 1;
 252   t = netg__lex(&p, vc);
 253
 254   for (;;) {
 255
 256     /* --- Start with a fresh cons cell, with an empty atom attached --- */
 257
 258     c = xmalloc(sizeof(*c));
 259     c->car.atom = xmalloc(sizeof(*c->car.atom));
 260
 261     /* --- Restart here after an error --- *
 262      *
 263      * If I restart here, I can avoid freeing the cons cell reallocating
 264      * it, which is a little silly.
 265      */
 266
 267   duff_restart:
 268     c->car.atom->n = c->car.atom->h = c->car.atom->u = c->car.atom->d = 0;
 269     c->f = 0;
 270     c->cdr = 0;
 271
 272     /* --- Handle end-of-line --- */
 273
 274     if (t == tok_eof)
 275       break;
 276
 277     /* --- Handle a netgroup reference --- */
 278
 279     if (t == tok_string) {
 280       T( trace(TRACE_DEBUG, "debug: add reference to `%s'", vc); )
 281       c->car.atom->n = xstrdup(vc);
 282       *link = c;
 283       link = &c->cdr;
 284       t = netg__lex(&p, vc);
 285       continue;
 286     }
 287
 288     /* --- Parse our merry way through the host--user--domain triple --- */
 289
 290     if (t != '(')
 291       goto duff;
 292     t = netg__lex(&p, vc);
 293
 294     if (t == tok_string) {
 295       T( trace(TRACE_DEBUG, "debug: add host `%s'", vc); )
 296       c->car.atom->h = xstrdup(vc);
 297       t = netg__lex(&p, vc);
 298     }
 299
 300     if (t != ',')
 301       goto duff_paren;
 302     t = netg__lex(&p, vc);
 303
 304     if (t == tok_string) {
 305       T( trace(TRACE_DEBUG, "debug: add user `%s'", vc); )
 306       c->car.atom->u = xstrdup(vc);
 307       t = netg__lex(&p, vc);
 308     }
 309
 310     if (t != ',')
 311       goto duff_paren;
 312     t = netg__lex(&p, vc);
 313
 314     if (t == tok_string) {
 315       T( trace(TRACE_DEBUG, "debug: add domain `%s'", vc); )
 316       c->car.atom->d = xstrdup(vc);
 317       t = netg__lex(&p, vc);
 318     }
 319
 320     if (t != ')')
 321       goto duff_paren;
 322     t = netg__lex(&p, vc);
 323
 324     /* --- Finished that, so insert this cons cell into the list --- */
 325
 326     *link = c;
 327     link = &c->cdr;
 328     continue;
 329
 330     /* --- Tidy up during scanning of a triple --- *
 331      *
 332      * I'll search for the closing paren, and hope that I won't miss out too
 333      * much.
 334      */
 335
 336   duff_paren:
 337     while (t != tok_eof && t != ')')
 338       t = netg__lex(&p, vc);
 339
 340     /* --- Other syntax oddnesses come out here --- *
 341      *
 342      * Snarf the token which caused the error.
 343      */
 344
 345   duff:
 346     moan("syntax error in netgroups line for `%s'", kc);
 347     if (c->car.atom->n) free(c->car.atom->n);
 348     if (c->car.atom->h) free(c->car.atom->h);
 349     if (c->car.atom->u) free(c->car.atom->u);
 350     if (c->car.atom->d) free(c->car.atom->d);
 351     t = netg__lex(&p, vc);
 352     goto duff_restart;
 353   }
 354
 355   free(c->car.atom);
 356   free(c);
 357   free(kc);
 358   free(vc);
 359   return (0);
 360 }
 361
 362 /* --- @netg__dumpGroup@ ---  *
 363  *
 364  * Arguments:   @netg__cons *c@ = pointer to a list head
 365  *              @int lev@ = indentation level
 366  *
 367  * Returns:     ---
 368  *
 369  * Use:         Dumps the netgroup given.
 370  */
 371
 372 #ifndef NTRACE
 373
 374 static void netg__dumpGroup(netg__cons *c, int lev)
 375 {
 376   netg__cons *cc;
 377
 378   if (!c)
 379     return;
 380
 381   /* --- Check for a cycle --- */
 382
 383   if (c->f & f_visit) {
 384     trace(TRACE_DEBUG, "debug: %*scycle!", lev * 2, "");
 385     return;
 386   }
 387
 388   /* --- Dump the netgroup --- */
 389
 390   c->f |= f_visit;
 391
 392   for (cc = c; cc; cc = cc->cdr) {
 393     if (cc->f & f_cons) {
 394       trace(TRACE_DEBUG, "debug: %*ssubnetgroup...", lev * 2, "");
 395       netg__dumpGroup(cc->car.cons, lev + 1);
 396     } else if (cc->car.atom->n) {
 397       trace(TRACE_DEBUG, "debug: %*sunresolved subgroup `%s'",
 398             lev * 2, "", cc->car.atom->n);
 399     } else {
 400       trace(TRACE_DEBUG, "debug: %*s(%s, %s, %s)", lev * 2, "",
 401             cc->car.atom->h ? cc->car.atom->h : "<all-hosts>",
 402             cc->car.atom->u ? cc->car.atom->u : "<all-users>",
 403             cc->car.atom->d ? cc->car.atom->d : "<all-domains>");
 404     }
 405   }
 406
 407   c->f &= ~f_visit;
 408 }
 409
 410 #endif
 411
 412 /* --- @netg__dump@ --- *
 413  *
 414  * Arguments:   ---
 415  *
 416  * Returns:     ---
 417  *
 418  * Use:         Dumps the netgroups table.
 419  */
 420
 421 #ifndef NTRACE
 422
 423 static void netg__dump(void)
 424 {
 425   sym_iter i;
 426   netg__sym *sng;
 427
 428   trace(TRACE_DEBUG, "debug: dumping netgroups file");
 429   for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 430     trace(TRACE_DEBUG, "debug: netgroup `%s'...", sng->_base.name);
 431     sng->cons->f &= ~f_visit;
 432     netg__dumpGroup(sng->cons, 1);
 433   }
 434 }
 435
 436 #endif
 437
 438 /* --- @netg_iterate@, @netg_iterate_r@ --- *
 439  *
 440  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 441  *
 442  * Returns:     ---
 443  *
 444  * Use:         Starts iterating over the netgroups.
 445  */
 446
 447 void netg_iterate(void) { netg_iterate_r(&netg__iter); }
 448 void netg_iterate_r(netg_iter *i) { sym_mkiter(i, &netg__table); }
 449
 450 /* --- @netg_next@, @netg_next_r@ --- *
 451  *
 452  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 453  *
 454  * Returns:     An opaque pointer to the next item, or null.
 455  *
 456  * Use:         Returns the next netgroup.
 457  */
 458
 459 netg *netg_next(void) { return (netg_next_r(&netg__iter)); }
 460 netg *netg_next_r(netg_iter *i) { return (sym_next(i)); }
 461
 462 /* --- @netg_name@ --- *
 463  *
 464  * Arguments:   @netg *n@ = netgroup handle returned by @netg_next@.
 465  *
 466  * Returns:     A pointer to the name; you may not modify this string.
 467  *
 468  * Use:         Returns the name of a netgroup.
 469  */
 470
 471 const char *netg_name(netg *n) { return (n->_base.name); }
 472
 473 /* --- @netg_scan@ --- *
 474  *
 475  * Arguments:   @netg *n@ = a netgroup handle returned by @netg_next@
 476  *              @int (*proc)(netg *n, const char *host, const char *user,@
 477  *                      @const char *domain, void *ctx)@ = function to call
 478  *                              for each member.
 479  *              @void *ctx@ = context pointer to pass to @proc@.
 480  *
 481  * Returns:     Zero if all went well, or the nonzero return value from
 482  *              @proc@.
 483  *
 484  * Use:         Passes all the members of the netgroup to a given function.
 485  *              The function is given the names, directly from the NIS
 486  *              netgroup map, except that any empty entries are passed as
 487  *              null pointers rather than empty strings.  You may not modify
 488  *              any of the strings.  The enumeration function, @proc@, may
 489  *              return nonzero to stop itself from being called any more;
 490  *              if this happens, the value it returns becomes the result of
 491  *              this function.  If all the items are enumerated OK, this
 492  *              function returns zero.
 493  */
 494
 495 static int netg__doScan(netg__cons *c,
 496                         netg *n,
 497                         int (*proc)(netg */*n*/, const char */*host*/,
 498                                     const char */*user*/,
 499                                     const char */*domain*/, void */*ctx*/),
 500                         void *ctx)
 501 {
 502   int e;
 503
 504   while (c) {
 505     if (c->f & f_cons)
 506       e = netg__doScan(c->car.cons, n, proc, ctx);
 507     else
 508       e = proc(n, c->car.atom->h, c->car.atom->u, c->car.atom->d, ctx);
 509     if (e)
 510       return (e);
 511     c = c->cdr;
 512   }
 513   return (0);
 514 }
 515
 516 int netg_scan(netg *n,
 517               int (*proc)(netg */*n*/, const char */*host*/,
 518                           const char */*user*/, const char */*domain*/,
 519                           void */*ctx*/),
 520               void *ctx)
 521 {
 522   return (netg__doScan(n->cons, n, proc, ctx));
 523 }
 524
 525 /* --- @netg__breakCycle@ --- *
 526  *
 527  * Arguments:   @netg__cons *c@ = pointer to a list
 528  *
 529  * Returns:     ---
 530  *
 531  * Use:         Scans the given list (recursively) and breaks any cycles it
 532  *              finds.
 533  */
 534
 535 static void netg__breakCycle(netg__cons *c)
 536 {
 537   netg__cons *cc;
 538
 539   if (!c || c->f & f_uncycled)
 540     return;
 541
 542   c->f |= f_visit;
 543   for (cc = c; cc; cc = cc->cdr) {
 544     if (~cc->f & f_cons)
 545       continue;
 546     if (cc->car.cons->f & f_visit) {
 547       T( trace(TRACE_DEBUG, "debug: cycle in netgroups"); )
 548       cc->car.cons = 0;
 549     } else
 550       netg__breakCycle(cc->car.cons);
 551   }
 552   c->f &= ~f_visit;
 553   c->f |= f_uncycled;
 554 }
 555
 556 /* --- @netg_init@ --- *
 557  *
 558  * Arguments:   ---
 559  *
 560  * Returns:     ---
 561  *
 562  * Use:         Reads the netgroup database and turns it into something nice.
 563  */
 564
 565 void netg_init(void)
 566 {
 567   /* --- Initialise my symbol table --- */
 568
 569   sym_create(&netg__table);
 570
 571   /* --- Bind myself unto a YP server --- */
 572
 573   ypstuff_bind();
 574   if (!yp_domain)
 575     return;
 576
 577   /* --- Now try to read all the netgroup entries --- */
 578
 579   {
 580     static struct ypall_callback ncb = { netg__foreach, 0 };
 581     yp_all(yp_domain, "netgroup", &ncb);
 582   }
 583
 584   /* --- Dump the table --- */
 585
 586   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 587
 588   /* --- Now resolve all the remaining references --- */
 589
 590   {
 591     sym_iter i;
 592     netg__sym *sng, *ng;
 593     netg__cons *c;
 594     netg__atom *a;
 595
 596     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 597       for (c = sng->cons; c; c = c->cdr) {
 598         if ((c->f & f_cons) == 0 && c->car.atom->n) {
 599           a = c->car.atom;
 600           ng = sym_find(&netg__table, a->n, -1, 0, 0);
 601           if (!ng) {
 602             moan("undefined netgroup `%s' (ignored)", a->n);
 603             c->car.atom = 0;
 604           } else {
 605             c->car.cons = ng->cons;
 606             c->f |= f_cons;
 607           }
 608           free(a->n);
 609           free(a);
 610         }
 611       }
 612     }
 613   }
 614
 615   /* --- Remove cycles in the netgroups table --- */
 616
 617   {
 618     sym_iter i;
 619     netg__sym *sng;
 620
 621     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 622       sng->cons->f &= ~f_uncycled;
 623     for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 624       netg__breakCycle(sng->cons);
 625   }
 626
 627   /* --- Dump the table again --- */
 628
 629   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 630 }
 631
 632 /* --- @netg_end@ --- *
 633  *
 634  * Arguments:   ---
 635  *
 636  * Returns:     ---
 637  *
 638  * Use:         Empties the netgroups database.
 639  */
 640
 641 void netg_end(void)
 642 {
 643   sym_iter i;
 644   netg__sym *sng;
 645   netg__cons *c, *cc;
 646
 647   /* --- Remove all the old netgroups rubbish --- */
 648
 649   for (sym_mkiter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 650     c = sng->cons;
 651     while (c) {
 652       cc = c->cdr;
 653       if (~c->f & f_cons) {
 654         if (c->car.atom->n) free(c->car.atom->n);
 655         if (c->car.atom->h) free(c->car.atom->h);
 656         if (c->car.atom->u) free(c->car.atom->u);
 657         if (c->car.atom->d) free(c->car.atom->d);
 658         free(c->car.atom);
 659       }
 660       free(c);
 661       c = cc;
 662     }
 663     sym_remove(&netg__table, sng);
 664   }
 665
 666   sym_destroy(&netg__table);
 667 }
 668
 669 /*----- Test driver -------------------------------------------------------*/
 670
 671 #ifdef TEST_RIG
 672
 673 int scanner(netg *n, const char *h, const char *u, const char *d, void *c)
 674 {
 675   fprintf(stderr, "  %s, %s, %s\n",
 676           h ? h : "<any>", u ? u : "<any>", d ? d : "<any>");
 677   return (0);
 678 }
 679
 680 int main(void)
 681 {
 682   netg *n;
 683   ego("netg-test");
 684   traceon(stderr, TRACE_ALL);
 685   netg_init();
 686   for (netg_iterate(); (n = netg_next()) != 0; ) {
 687     fprintf(stderr, "netgroup %s\n", netg_name(n));
 688     netg_scan(n, scanner, 0);
 689   }
 690   return (0);
 691 }
 692
 693 #endif
 694
 695 /*----- That's all, folks -------------------------------------------------*/