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

   1 /* -*-c-*-
   2  *
   3  * $Id: netg.c,v 1.2 1997/08/20 16:19:11 mdw Exp $
   4  *
   5  * A local database of netgroups
   6  *
   7  * (c) 1997 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 1.2  1997/08/20 16:19:11  mdw
  33  * Patch memory leak.  Replace `name_reinit' by `name_end' for more sensible
  34  * restart.  Don't try to trace when tracing's turned off.
  35  *
  36  * Revision 1.1  1997/08/07 09:45:00  mdw
  37  * New source file added to maintain a netgroups database.
  38  *
  39  */
  40
  41 /*----- Header files ------------------------------------------------------*/
  42
  43 /* --- ANSI headers --- */
  44
  45 #include <ctype.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include <string.h>
  49
  50 /* --- Unix headers --- */
  51
  52 #include "config.h"
  53
  54 #include <sys/types.h>
  55
  56 #ifdef HAVE_YP
  57 #  include <rpc/rpc.h>
  58 #  include <rpcsvc/ypclnt.h>
  59 #  include <rpcsvc/yp_prot.h>
  60 #endif
  61
  62 #include <netinet/in.h>
  63
  64 #include <arpa/inet.h>
  65
  66 #include <pwd.h>
  67 #include <netdb.h>
  68 #include <unistd.h>
  69
  70 /* --- Local headers --- */
  71
  72 #include "become.h"
  73 #include "config.h"
  74 #include "netg.h"
  75 #include "sym.h"
  76 #include "userdb.h"
  77 #include "utils.h"
  78
  79 /*----- Type definitions --------------------------------------------------*/
  80
  81 /* --- Quick discussion --- *
  82  *
  83  * I've just noticed: netgroups are horrible.  They form a directed graph
  84  * which is really horrible; I'll have to try and turn it into something
  85  * more sensible (which will essentially involve cutting cycles).
  86  *
  87  * The structure looks a little bit like a good ol' List (see Knuth 1 or
  88  * any decent Lisp manual), but with more information in the cons cells.
  89  */
  90
  91 /* --- @netg__cons@ --- */
  92
  93 typedef struct netg__cons {
  94   unsigned f;
  95   union {
  96     struct netg__cons *cons;
  97     struct netg__atom *atom;
  98   } car;
  99   struct netg__cons *cdr;
 100 } netg__cons;
 101
 102 enum {
 103   f_cons = 1,                           /* The @car@ is a cons cell */
 104   f_visit = 2,                          /* Currently threaded on this cell */
 105   f_uncycled = 4                        /* Cycles removed from here on in */
 106 };
 107
 108 /* --- @netg__atom@ --- */
 109
 110 typedef struct netg__atom {
 111   char *n;                              /* Unresolved netgroup reference */
 112   char *h;                              /* Matched hostname */
 113   char *u;                              /* Matched user name */
 114   char *d;                              /* Matched domain name */
 115 } netg__atom;
 116
 117 /* --- @netg__sym@ --- */
 118
 119 typedef struct netg__sym {
 120   sym_base _base;
 121   netg__cons *cons;
 122 } netg__sym;
 123
 124 /* --- Token types for the netgroup parser --- */
 125
 126 enum {
 127   tok_string = 256,
 128   tok_eof
 129 };
 130
 131 /*----- Static variables --------------------------------------------------*/
 132
 133 static sym_table netg__table;           /* Netgroup table */
 134 static sym_iter netg__iter;             /* Iterator object for users */
 135
 136 /*----- Main code ---------------------------------------------------------*/
 137
 138 /* --- @netg__lex@ --- *
 139  *
 140  * Arguments:   @const char **p@ = pointer to next unscanned character
 141  *              @char *q@ = pointer to output buffer
 142  *
 143  * Returns:     Token type (either character code or a magic number).
 144  *
 145  * Use:         Lexes a netgroups line into tokens.
 146  */
 147
 148 static int netg__lex(char **p, char *q)
 149 {
 150   /* --- Skip any leading whitespace --- */
 151
 152   while (isspace((unsigned char)**p))
 153     (*p)++;
 154
 155   /* --- Now work out what we've got --- */
 156
 157   if (**p == 0)
 158     return (tok_eof);
 159   if (**p == '(' || **p == ')' || **p == ',')
 160     return (*(*p)++);
 161   do
 162     *q++ = *(*p)++;
 163   while (**p != 0 && **p != '(' && **p != ')' &&
 164          **p != ',' && !isspace((unsigned char)**p));
 165   *q++ = 0;
 166   return (tok_string);
 167 }
 168
 169 /* --- @netg__foreach@ --- *
 170  *
 171  * Arguments:   @int st@ = YP protocol-level status code
 172  *              @char *k@ = pointer to string containing the key
 173  *              @int ksz@ = length of the key string
 174  *              @char *v@ = pointer to string containing the value
 175  *              @int vsz@ = length of the value string
 176  *              @char *data@ = pointer to my data information
 177  *
 178  * Returns:     Zero to continue, nonzero for no more entries.
 179  *
 180  * Use:         Handles each incoming netgroup, attaching it to the table.
 181  */
 182
 183 static int netg__foreach(int st, char *k, int ksz,
 184                          char *v, int vsz, char *data)
 185 {
 186   char *kc, *vc;
 187   unsigned f;
 188   netg__sym *sng;
 189   netg__cons *c, **link;
 190   char *p;
 191   int t;
 192
 193   /* --- If something is amiss, then quit now --- */
 194
 195   if (st != YP_TRUE)
 196     return (-1);
 197
 198   /* --- Ignore empty lines from the original file --- */
 199
 200   if (!ksz || !vsz)
 201     return (0);
 202
 203   /* --- Build my own trashable copies of the key and value --- *
 204    *
 205    * Note the oddness when I copy the value string.  The extra byte at the
 206    * beginning allows me to use the same area of memory as an output buffer
 207    * for the lexer.  It must be big enough; the lexer doesn't back up; and
 208    * that extra byte gives me somewhere to put a terminating null byte.
 209    */
 210
 211   kc = xmalloc(ksz + 1);
 212   memcpy(kc, k, ksz);
 213   kc[ksz] = 0;
 214
 215   vc = xmalloc(vsz + 2);
 216   memcpy(vc + 1, v, vsz);
 217   vc[vsz + 1] = 0;
 218
 219   T( trace(TRACE_DEBUG, "debug: netgroup `%s': `%s'", kc, vc + 1); )
 220
 221   /* --- Allocate a symbol in my table --- */
 222
 223   sng = sym_find(&netg__table, kc, -1, sizeof(*sng), &f);
 224   if (!f)
 225     sng->cons = 0;
 226
 227   /* --- Run to the end of the list --- */
 228
 229   for (link = &sng->cons; *link; link = &((*link)->cdr))
 230     ;
 231
 232   /* --- Now start the tricky bit --- *
 233    *
 234    * I have to start parsing the netgroup value string.  Oh, well, it
 235    * could be worse.
 236    *
 237    * The parser is written so as to avoid saying things more often than
 238    * necessary.  This tends to involve @goto@s.  You've been warned.
 239    */
 240
 241   p = vc + 1;
 242   t = netg__lex(&p, vc);
 243
 244   for (;;) {
 245
 246     /* --- Start with a fresh cons cell, with an empty atom attached --- */
 247
 248     c = xmalloc(sizeof(*c));
 249     c->car.atom = xmalloc(sizeof(*c->car.atom));
 250
 251     /* --- Restart here after an error --- *
 252      *
 253      * If I restart here, I can avoid freeing the cons cell reallocating
 254      * it, which is a little silly.
 255      */
 256
 257   duff_restart:
 258     c->car.atom->n = c->car.atom->h = c->car.atom->u = c->car.atom->d = 0;
 259     c->f = 0;
 260     c->cdr = 0;
 261
 262     /* --- Handle end-of-line --- */
 263
 264     if (t == tok_eof)
 265       break;
 266
 267     /* --- Handle a netgroup reference --- */
 268
 269     if (t == tok_string) {
 270       T( trace(TRACE_DEBUG, "debug: add reference to `%s'", vc); )
 271       c->car.atom->n = xstrdup(vc);
 272       *link = c;
 273       link = &c->cdr;
 274       t = netg__lex(&p, vc);
 275       continue;
 276     }
 277
 278     /* --- Parse our merry way through the host--user--domain triple --- */
 279
 280     if (t != '(')
 281       goto duff;
 282     t = netg__lex(&p, vc);
 283
 284     if (t == tok_string) {
 285       T( trace(TRACE_DEBUG, "debug: add host `%s'", vc); )
 286       c->car.atom->h = xstrdup(vc);
 287       t = netg__lex(&p, vc);
 288     }
 289
 290     if (t != ',')
 291       goto duff_paren;
 292     t = netg__lex(&p, vc);
 293
 294     if (t == tok_string) {
 295       T( trace(TRACE_DEBUG, "debug: add user `%s'", vc); )
 296       c->car.atom->u = 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 domain `%s'", vc); )
 306       c->car.atom->d = 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     /* --- Finished that, so insert this cons cell into the list --- */
 315
 316     *link = c;
 317     link = &c->cdr;
 318     continue;
 319
 320     /* --- Tidy up during scanning of a triple --- *
 321      *
 322      * I'll search for the closing paren, and hope that I won't miss out too
 323      * much.
 324      */
 325
 326   duff_paren:
 327     while (t != tok_eof && t != ')')
 328       t = netg__lex(&p, vc);
 329
 330     /* --- Other syntax oddnesses come out here --- *
 331      *
 332      * Snarf the token which caused the error.
 333      */
 334
 335   duff:
 336     moan("syntax error in netgroups line for `%s'", kc);
 337     if (c->car.atom->n) free(c->car.atom->n);
 338     if (c->car.atom->h) free(c->car.atom->h);
 339     if (c->car.atom->u) free(c->car.atom->u);
 340     if (c->car.atom->d) free(c->car.atom->d);
 341     t = netg__lex(&p, vc);
 342     goto duff_restart;
 343   }
 344
 345   free(c->car.atom);
 346   free(c);
 347   free(kc);
 348   free(vc);
 349   return (0);
 350 }
 351
 352 /* --- @netg__dumpGroup@ ---  *
 353  *
 354  * Arguments:   @netg__cons *c@ = pointer to a list head
 355  *              @int lev@ = indentation level
 356  *
 357  * Returns:     ---
 358  *
 359  * Use:         Dumps the netgroup given.
 360  */
 361
 362 #ifdef TRACING
 363
 364 static void netg__dumpGroup(netg__cons *c, int lev)
 365 {
 366   netg__cons *cc;
 367
 368   if (!c)
 369     return;
 370
 371   /* --- Check for a cycle --- */
 372
 373   if (c->f & f_visit) {
 374     trace(TRACE_DEBUG, "debug: %*scycle!", lev * 2, "");
 375     return;
 376   }
 377
 378   /* --- Dump the netgroup --- */
 379
 380   c->f |= f_visit;
 381
 382   for (cc = c; cc; cc = cc->cdr) {
 383     if (cc->f & f_cons) {
 384       trace(TRACE_DEBUG, "debug: %*ssubnetgroup...", lev * 2, "");
 385       netg__dumpGroup(cc->car.cons, lev + 1);
 386     } else if (cc->car.atom->n) {
 387       trace(TRACE_DEBUG, "debug: %*sunresolved subgroup `%s'",
 388             lev * 2, "", cc->car.atom->n);
 389     } else {
 390       trace(TRACE_DEBUG, "debug: %*s(%s, %s, %s)", lev * 2, "",
 391             cc->car.atom->h ? cc->car.atom->h : "<all-hosts>",
 392             cc->car.atom->u ? cc->car.atom->u : "<all-users>",
 393             cc->car.atom->d ? cc->car.atom->d : "<all-domains>");
 394     }
 395   }
 396
 397   c->f &= ~f_visit;
 398 }
 399
 400 #endif
 401
 402 /* --- @netg__dump@ --- *
 403  *
 404  * Arguments:   ---
 405  *
 406  * Returns:     ---
 407  *
 408  * Use:         Dumps the netgroups table.
 409  */
 410
 411 #ifdef TRACING
 412
 413 static void netg__dump(void)
 414 {
 415   sym_iter i;
 416   netg__sym *sng;
 417
 418   trace(TRACE_DEBUG, "debug: dumping netgroups file");
 419   for (sym_createIter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 420     trace(TRACE_DEBUG, "debug: netgroup `%s'...", sng->_base.name);
 421     sng->cons->f &= ~f_visit;
 422     netg__dumpGroup(sng->cons, 1);
 423   }
 424 }
 425
 426 #endif
 427
 428 /* --- @netg_iterate@, @netg_iterate_r@ --- *
 429  *
 430  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 431  *
 432  * Returns:     ---
 433  *
 434  * Use:         Starts iterating over the netgroups.
 435  */
 436
 437 void netg_iterate(void) { netg_iterate_r(&netg__iter); }
 438 void netg_iterate_r(netg_iter *i) { sym_createIter(i, &netg__table); }
 439
 440 /* --- @netg_next@, @netg_next_r@ --- *
 441  *
 442  * Arguments:   @netg_iter *i@ = pointer to a netgroup iterator object
 443  *
 444  * Returns:     An opaque pointer to the next item, or null.
 445  *
 446  * Use:         Returns the next netgroup.
 447  */
 448
 449 netg *netg_next(void) { return (netg_next_r(&netg__iter)); }
 450 netg *netg_next_r(netg_iter *i) { return (sym_next(i)); }
 451
 452 /* --- @netg_name@ --- *
 453  *
 454  * Arguments:   @netg *n@ = netgroup handle returned by @netg_next@.
 455  *
 456  * Returns:     A pointer to the name; you may not modify this string.
 457  *
 458  * Use:         Returns the name of a netgroup.
 459  */
 460
 461 const char *netg_name(netg *n) { return (n->_base.name); }
 462
 463 /* --- @netg_scan@ --- *
 464  *
 465  * Arguments:   @netg *n@ = a netgroup handle returned by @netg_next@
 466  *              @int (*proc)(netg *n, const char *host, const char *user,@
 467  *                      @const char *domain, void *ctx)@ = function to call
 468  *                              for each member.
 469  *              @void *ctx@ = context pointer to pass to @proc@.
 470  *
 471  * Returns:     Zero if all went well, or the nonzero return value from
 472  *              @proc@.
 473  *
 474  * Use:         Passes all the members of the netgroup to a given function.
 475  *              The function is given the names, directly from the NIS
 476  *              netgroup map, except that any empty entries are passed as
 477  *              null pointers rather than empty strings.  You may not modify
 478  *              any of the strings.  The enumeration function, @proc@, may
 479  *              return nonzero to stop itself from being called any more;
 480  *              if this happens, the value it returns becomes the result of
 481  *              this function.  If all the items are enumerated OK, this
 482  *              function returns zero.
 483  */
 484
 485 static int netg__doScan(netg__cons *c,
 486                         netg *n,
 487                         int (*proc)(netg */*n*/, const char */*host*/,
 488                                     const char */*user*/,
 489                                     const char */*domain*/, void */*ctx*/),
 490                         void *ctx)
 491 {
 492   int e;
 493
 494   while (c) {
 495     if (c->f & f_cons)
 496       e = netg__doScan(c->car.cons, n, proc, ctx);
 497     else
 498       e = proc(n, c->car.atom->h, c->car.atom->u, c->car.atom->d, ctx);
 499     if (e)
 500       return (e);
 501     c = c->cdr;
 502   }
 503   return (0);
 504 }
 505
 506 int netg_scan(netg *n,
 507               int (*proc)(netg */*n*/, const char */*host*/,
 508                           const char */*user*/, const char */*domain*/,
 509                           void */*ctx*/),
 510               void *ctx)
 511 {
 512   return (netg__doScan(n->cons, n, proc, ctx));
 513 }
 514
 515 /* --- @netg__breakCycle@ --- *
 516  *
 517  * Arguments:   @netg__cons *c@ = pointer to a list
 518  *
 519  * Returns:     ---
 520  *
 521  * Use:         Scans the given list (recursively) and breaks any cycles it
 522  *              finds.
 523  */
 524
 525 static void netg__breakCycle(netg__cons *c)
 526 {
 527   netg__cons *cc;
 528
 529   if (!c || c->f & f_uncycled)
 530     return;
 531
 532   c->f |= f_visit;
 533   for (cc = c; cc; cc = cc->cdr) {
 534     if (~cc->f & f_cons)
 535       continue;
 536     if (cc->car.cons->f & f_visit) {
 537       T( trace(TRACE_DEBUG, "debug: cycle in netgroups"); )
 538       cc->car.cons = 0;
 539     } else
 540       netg__breakCycle(cc->car.cons);
 541   }
 542   c->f &= ~f_visit;
 543   c->f |= f_uncycled;
 544 }
 545
 546 /* --- @netg_init@ --- *
 547  *
 548  * Arguments:   ---
 549  *
 550  * Returns:     ---
 551  *
 552  * Use:         Reads the netgroup database and turns it into something nice.
 553  */
 554
 555 void netg_init(void)
 556 {
 557   char *ypdom;
 558
 559   /* --- Initialise my symbol table --- */
 560
 561   sym_createTable(&netg__table);
 562
 563   /* --- Bind myself unto a YP server --- */
 564
 565   if (yp_get_default_domain(&ypdom) ||
 566       yp_bind(ypdom))
 567     return;
 568
 569   /* --- Now try to read all the netgroup entries --- */
 570
 571   {
 572     static struct ypall_callback ncb = { netg__foreach, 0 };
 573     yp_all(ypdom, "netgroup", &ncb);
 574   }
 575
 576   /* --- Unbind from the server --- */
 577
 578   yp_unbind(ypdom);
 579
 580   /* --- Dump the table --- */
 581
 582   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 583
 584   /* --- Now resolve all the remaining references --- */
 585
 586   {
 587     sym_iter i;
 588     netg__sym *sng, *ng;
 589     netg__cons *c;
 590     netg__atom *a;
 591
 592     for (sym_createIter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 593       for (c = sng->cons; c; c = c->cdr) {
 594         if ((c->f & f_cons) == 0 && c->car.atom->n) {
 595           a = c->car.atom;
 596           ng = sym_find(&netg__table, a->n, -1, 0, 0);
 597           if (!ng) {
 598             moan("undefined netgroup `%s' (ignored)", a->n);
 599             c->car.atom = 0;
 600           } else {
 601             c->car.cons = ng->cons;
 602             c->f |= f_cons;
 603           }
 604           free(a->n);
 605           free(a);
 606         }
 607       }
 608     }
 609   }
 610
 611   /* --- Remove cycles in the netgroups table --- */
 612
 613   {
 614     sym_iter i;
 615     netg__sym *sng;
 616
 617     for (sym_createIter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 618       sng->cons->f &= ~f_uncycled;
 619     for (sym_createIter(&i, &netg__table); (sng = sym_next(&i)) != 0; )
 620       netg__breakCycle(sng->cons);
 621   }
 622
 623   /* --- Dump the table again --- */
 624
 625   IF_TRACING(TRACE_DEBUG, netg__dump(); )
 626 }
 627
 628 /* --- @netg_end@ --- *
 629  *
 630  * Arguments:   ---
 631  *
 632  * Returns:     ---
 633  *
 634  * Use:         Empties the netgroups database.
 635  */
 636
 637 void netg_end(void)
 638 {
 639   sym_iter i;
 640   netg__sym *sng;
 641   netg__cons *c, *cc;
 642
 643   /* --- Remove all the old netgroups rubbish --- */
 644
 645   for (sym_createIter(&i, &netg__table); (sng = sym_next(&i)) != 0; ) {
 646     c = sng->cons;
 647     while (c) {
 648       cc = c->cdr;
 649       if (~c->f & f_cons) {
 650         if (c->car.atom->n) free(c->car.atom->n);
 651         if (c->car.atom->h) free(c->car.atom->h);
 652         if (c->car.atom->u) free(c->car.atom->u);
 653         if (c->car.atom->d) free(c->car.atom->d);
 654         free(c->car.atom);
 655       }
 656       free(c);
 657       c = cc;
 658     }
 659     sym_remove(&netg__table, sng);
 660   }
 661
 662   sym_destroyTable(&netg__table);
 663 }
 664
 665 /*----- Test driver -------------------------------------------------------*/
 666
 667 #ifdef TEST_RIG
 668
 669 int scanner(netg *n, const char *h, const char *u, const char *d, void *c)
 670 {
 671   fprintf(stderr, "  %s, %s, %s\n",
 672           h ? h : "<any>", u ? u : "<any>", d ? d : "<any>");
 673   return (0);
 674 }
 675
 676 int main(void)
 677 {
 678   netg *n;
 679   ego("netg-test");
 680   traceon(stderr, TRACE_ALL);
 681   netg_init();
 682   for (netg_iterate(); (n = netg_next()) != 0; ) {
 683     fprintf(stderr, "netgroup %s\n", netg_name(n));
 684     netg_scan(n, scanner, 0);
 685   }
 686   return (0);
 687 }
 688
 689 #endif
 690
 691 /*----- That's all, folks -------------------------------------------------*/