resolv/res_init.c

   1 /*
   2  * Copyright (c) 1985, 1989, 1993
   3  *    The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  */
  29
  30 /*
  31  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  32  *
  33  * Permission to use, copy, modify, and distribute this software for any
  34  * purpose with or without fee is hereby granted, provided that the above
  35  * copyright notice and this permission notice appear in all copies, and that
  36  * the name of Digital Equipment Corporation not be used in advertising or
  37  * publicity pertaining to distribution of the document or software without
  38  * specific, written prior permission.
  39  *
  40  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  41  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  42  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  43  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  44  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  45  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  46  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  47  * SOFTWARE.
  48  */
  49
  50 /*
  51  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  52  *
  53  * Permission to use, copy, modify, and distribute this software for any
  54  * purpose with or without fee is hereby granted, provided that the above
  55  * copyright notice and this permission notice appear in all copies.
  56  *
  57  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  58  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  59  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  60  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  61  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  62  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  63  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  64  * SOFTWARE.
  65  */
  66
  67 #if defined(LIBC_SCCS) && !defined(lint)
  68 static const char sccsid[] = "@(#)res_init.c    8.1 (Berkeley) 6/7/93";
  69 static const char rcsid[] = "$BINDId: res_init.c,v 8.16 2000/05/09 07:10:12 vixie Exp $";
  70 #endif /* LIBC_SCCS and not lint */
  71
  72 #include <sys/types.h>
  73 #include <sys/param.h>
  74 #include <sys/socket.h>
  75 #include <sys/time.h>
  76
  77 #include <netinet/in.h>
  78 #include <arpa/inet.h>
  79 #include <arpa/nameser.h>
  80
  81 #include <ctype.h>
  82 #include <resolv.h>
  83 #include <stdio.h>
  84 #include <stdlib.h>
  85 #include <string.h>
  86 #include <unistd.h>
  87
  88 /* Options.  Should all be left alone. */
  89 #define RESOLVSORT
  90 #define RFC1535
  91 /* #undef DEBUG */
  92
  93 static void res_setoptions (res_state, const char *, const char *)
  94      internal_function;
  95
  96 #ifdef RESOLVSORT
  97 static const char sort_mask[] = "/&";
  98 #define ISSORTMASK(ch) (strchr(sort_mask, ch) != NULL)
  99 static u_int32_t net_mask __P((struct in_addr));
 100 #endif
 101
 102 #if !defined(isascii)   /* XXX - could be a function */
 103 # define isascii(c) (!(c & 0200))
 104 #endif
 105
 106 /*
 107  * Resolver state default settings.
 108  */
 109
 110 /*
 111  * Set up default settings.  If the configuration file exist, the values
 112  * there will have precedence.  Otherwise, the server address is set to
 113  * INADDR_ANY and the default domain name comes from the gethostname().
 114  *
 115  * An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
 116  * rather than INADDR_ANY ("0.0.0.0") as the default name server address
 117  * since it was noted that INADDR_ANY actually meant ``the first interface
 118  * you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
 119  * it had to be "up" in order for you to reach your own name server.  It
 120  * was later decided that since the recommended practice is to always
 121  * install local static routes through 127.0.0.1 for all your network
 122  * interfaces, that we could solve this problem without a code change.
 123  *
 124  * The configuration file should always be used, since it is the only way
 125  * to specify a default domain.  If you are running a server on your local
 126  * machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
 127  * in the configuration file.
 128  *
 129  * Return 0 if completes successfully, -1 on error
 130  */
 131 int
 132 res_ninit(res_state statp) {
 133         extern int __res_vinit(res_state, int);
 134
 135         return (__res_vinit(statp, 0));
 136 }
 137
 138 /* This function has to be reachable by res_data.c but not publically. */
 139 int
 140 __res_vinit(res_state statp, int preinit) {
 141         register FILE *fp;
 142         register char *cp, **pp;
 143         register int n;
 144         char buf[BUFSIZ];
 145         int nserv = 0;    /* number of nameserver records read from file */
 146 #ifdef _LIBC
 147         int nservall = 0; /* number of NS records read, nserv IPv4 only */
 148 #endif
 149         int haveenv = 0;
 150         int havesearch = 0;
 151 #ifdef RESOLVSORT
 152         int nsort = 0;
 153         char *net;
 154 #endif
 155 #ifndef RFC1535
 156         int dots;
 157 #endif
 158
 159         if (!preinit) {
 160                 statp->retrans = RES_TIMEOUT;
 161                 statp->retry = RES_DFLRETRY;
 162                 statp->options = RES_DEFAULT;
 163                 statp->id = res_randomid();
 164         }
 165
 166 #ifdef USELOOPBACK
 167         statp->nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
 168 #else
 169         statp->nsaddr.sin_addr.s_addr = INADDR_ANY;
 170 #endif
 171         statp->nsaddr.sin_family = AF_INET;
 172         statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
 173         statp->nscount = 1;
 174         statp->ndots = 1;
 175         statp->pfcode = 0;
 176         statp->_vcsock = -1;
 177         statp->_flags = 0;
 178         statp->qhook = NULL;
 179         statp->rhook = NULL;
 180         statp->_u._ext.nsinit = 0;
 181         statp->_u._ext.nscount = 0;
 182 #ifdef _LIBC
 183         statp->_u._ext.nscount6 = 0;
 184         for (n = 0; n < MAXNS; n++)
 185             statp->_u._ext.nsaddrs[n] = NULL;
 186 #endif
 187
 188         /* Allow user to override the local domain definition */
 189         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 190                 (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 191                 statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 192                 haveenv++;
 193
 194                 /*
 195                  * Set search list to be blank-separated strings
 196                  * from rest of env value.  Permits users of LOCALDOMAIN
 197                  * to still have a search list, and anyone to set the
 198                  * one that they want to use as an individual (even more
 199                  * important now that the rfc1535 stuff restricts searches)
 200                  */
 201                 cp = statp->defdname;
 202                 pp = statp->dnsrch;
 203                 *pp++ = cp;
 204                 for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 205                         if (*cp == '\n')        /* silly backwards compat */
 206                                 break;
 207                         else if (*cp == ' ' || *cp == '\t') {
 208                                 *cp = 0;
 209                                 n = 1;
 210                         } else if (n) {
 211                                 *pp++ = cp;
 212                                 n = 0;
 213                                 havesearch = 1;
 214                         }
 215                 }
 216                 /* null terminate last domain if there are excess */
 217                 while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
 218                         cp++;
 219                 *cp = '\0';
 220                 *pp++ = 0;
 221         }
 222
 223 #define MATCH(line, name) \
 224         (!strncmp(line, name, sizeof(name) - 1) && \
 225         (line[sizeof(name) - 1] == ' ' || \
 226          line[sizeof(name) - 1] == '\t'))
 227
 228         if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
 229             /* read the config file */
 230             while (fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
 231                 /* skip comments */
 232                 if (*buf == ';' || *buf == '#')
 233                         continue;
 234                 /* read default domain name */
 235                 if (MATCH(buf, "domain")) {
 236                     if (haveenv)        /* skip if have from environ */
 237                             continue;
 238                     cp = buf + sizeof("domain") - 1;
 239                     while (*cp == ' ' || *cp == '\t')
 240                             cp++;
 241                     if ((*cp == '\0') || (*cp == '\n'))
 242                             continue;
 243                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 244                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 245                     if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
 246                             *cp = '\0';
 247                     havesearch = 0;
 248                     continue;
 249                 }
 250                 /* set search list */
 251                 if (MATCH(buf, "search")) {
 252                     if (haveenv)        /* skip if have from environ */
 253                             continue;
 254                     cp = buf + sizeof("search") - 1;
 255                     while (*cp == ' ' || *cp == '\t')
 256                             cp++;
 257                     if ((*cp == '\0') || (*cp == '\n'))
 258                             continue;
 259                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 260                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 261                     if ((cp = strchr(statp->defdname, '\n')) != NULL)
 262                             *cp = '\0';
 263                     /*
 264                      * Set search list to be blank-separated strings
 265                      * on rest of line.
 266                      */
 267                     cp = statp->defdname;
 268                     pp = statp->dnsrch;
 269                     *pp++ = cp;
 270                     for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 271                             if (*cp == ' ' || *cp == '\t') {
 272                                     *cp = 0;
 273                                     n = 1;
 274                             } else if (n) {
 275                                     *pp++ = cp;
 276                                     n = 0;
 277                             }
 278                     }
 279                     /* null terminate last domain if there are excess */
 280                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 281                             cp++;
 282                     *cp = '\0';
 283                     *pp++ = 0;
 284                     havesearch = 1;
 285                     continue;
 286                 }
 287                 /* read nameservers to query */
 288 #ifdef _LIBC
 289                 if (MATCH(buf, "nameserver") && nservall < MAXNS) {
 290 #else
 291                 if (MATCH(buf, "nameserver") && nserv < MAXNS) {
 292 #endif
 293                     struct in_addr a;
 294
 295                     cp = buf + sizeof("nameserver") - 1;
 296                     while (*cp == ' ' || *cp == '\t')
 297                         cp++;
 298                     if ((*cp != '\0') && (*cp != '\n')
 299                         && __inet_aton(cp, &a)) {
 300                         statp->nsaddr_list[nserv].sin_addr = a;
 301                         statp->nsaddr_list[nserv].sin_family = AF_INET;
 302                         statp->nsaddr_list[nserv].sin_port =
 303                                 htons(NAMESERVER_PORT);
 304                         nserv++;
 305 #ifdef _LIBC
 306                         nservall++;
 307                     } else {
 308                         struct in6_addr a6;
 309                         char *el;
 310
 311                         if ((el = strchr(cp, '\n')) != NULL)
 312                             *el = '\0';
 313                         if ((*cp != '\0') &&
 314                             (inet_pton(AF_INET6, cp, &a6) > 0)) {
 315                             struct sockaddr_in6 *sa6;
 316
 317                             sa6 = malloc(sizeof(*sa6));
 318                             if (sa6 != NULL) {
 319                                 sa6->sin6_addr = a6;
 320                                 sa6->sin6_family = AF_INET6;
 321                                 sa6->sin6_port = htons(NAMESERVER_PORT);
 322                                 statp->_u._ext.nsaddrs[nservall] = sa6;
 323                                 statp->_u._ext.nstimes[nservall] = RES_MAXTIME;
 324                                 statp->_u._ext.nssocks[nservall] = -1;
 325                                 nservall++;
 326                             }
 327                         }
 328 #endif
 329                     }
 330                     continue;
 331                 }
 332 #ifdef RESOLVSORT
 333                 if (MATCH(buf, "sortlist")) {
 334                     struct in_addr a;
 335
 336                     cp = buf + sizeof("sortlist") - 1;
 337                     while (nsort < MAXRESOLVSORT) {
 338                         while (*cp == ' ' || *cp == '\t')
 339                             cp++;
 340                         if (*cp == '\0' || *cp == '\n' || *cp == ';')
 341                             break;
 342                         net = cp;
 343                         while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
 344                                isascii(*cp) && !isspace(*cp))
 345                                 cp++;
 346                         n = *cp;
 347                         *cp = 0;
 348                         if (__inet_aton(net, &a)) {
 349                             statp->sort_list[nsort].addr = a;
 350                             if (ISSORTMASK(n)) {
 351                                 *cp++ = n;
 352                                 net = cp;
 353                                 while (*cp && *cp != ';' &&
 354                                         isascii(*cp) && !isspace(*cp))
 355                                     cp++;
 356                                 n = *cp;
 357                                 *cp = 0;
 358                                 if (__inet_aton(net, &a)) {
 359                                     statp->sort_list[nsort].mask = a.s_addr;
 360                                 } else {
 361                                     statp->sort_list[nsort].mask =
 362                                         net_mask(statp->sort_list[nsort].addr);
 363                                 }
 364                             } else {
 365                                 statp->sort_list[nsort].mask =
 366                                     net_mask(statp->sort_list[nsort].addr);
 367                             }
 368                             nsort++;
 369                         }
 370                         *cp = n;
 371                     }
 372                     continue;
 373                 }
 374 #endif
 375                 if (MATCH(buf, "options")) {
 376                     res_setoptions(statp, buf + sizeof("options") - 1, "conf");
 377                     continue;
 378                 }
 379             }
 380             if (nserv > 1)
 381                 statp->nscount = nserv;
 382 #ifdef _LIBC
 383             if (nservall - nserv > 0)
 384                 statp->_u._ext.nscount6 = nservall - nserv;
 385 #endif
 386 #ifdef RESOLVSORT
 387             statp->nsort = nsort;
 388 #endif
 389             (void) fclose(fp);
 390         }
 391         if (statp->defdname[0] == 0 &&
 392             __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
 393             (cp = strchr(buf, '.')) != NULL)
 394                 strcpy(statp->defdname, cp + 1);
 395
 396         /* find components of local domain that might be searched */
 397         if (havesearch == 0) {
 398                 pp = statp->dnsrch;
 399                 *pp++ = statp->defdname;
 400                 *pp = NULL;
 401
 402 #ifndef RFC1535
 403                 dots = 0;
 404                 for (cp = statp->defdname; *cp; cp++)
 405                         dots += (*cp == '.');
 406
 407                 cp = statp->defdname;
 408                 while (pp < statp->dnsrch + MAXDFLSRCH) {
 409                         if (dots < LOCALDOMAINPARTS)
 410                                 break;
 411                         cp = __rawmemchr(cp, '.') + 1;    /* we know there is one */
 412                         *pp++ = cp;
 413                         dots--;
 414                 }
 415                 *pp = NULL;
 416 #ifdef DEBUG
 417                 if (statp->options & RES_DEBUG) {
 418                         printf(";; res_init()... default dnsrch list:\n");
 419                         for (pp = statp->dnsrch; *pp; pp++)
 420                                 printf(";;\t%s\n", *pp);
 421                         printf(";;\t..END..\n");
 422                 }
 423 #endif
 424 #endif /* !RFC1535 */
 425         }
 426
 427         if ((cp = getenv("RES_OPTIONS")) != NULL)
 428                 res_setoptions(statp, cp, "env");
 429         statp->options |= RES_INIT;
 430         return (0);
 431 }
 432
 433 static void
 434 internal_function
 435 res_setoptions(res_state statp, const char *options, const char *source) {
 436         const char *cp = options;
 437         int i;
 438
 439 #ifdef DEBUG
 440         if (statp->options & RES_DEBUG)
 441                 printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 442                        options, source);
 443 #endif
 444         while (*cp) {
 445                 /* skip leading and inner runs of spaces */
 446                 while (*cp == ' ' || *cp == '\t')
 447                         cp++;
 448                 /* search for and process individual options */
 449                 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
 450                         i = atoi(cp + sizeof("ndots:") - 1);
 451                         if (i <= RES_MAXNDOTS)
 452                                 statp->ndots = i;
 453                         else
 454                                 statp->ndots = RES_MAXNDOTS;
 455 #ifdef DEBUG
 456                         if (statp->options & RES_DEBUG)
 457                                 printf(";;\tndots=%d\n", statp->ndots);
 458 #endif
 459                 } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 460                         i = atoi(cp + sizeof("timeout:") - 1);
 461                         if (i <= RES_MAXRETRANS)
 462                                 statp->retrans = i;
 463                         else
 464                                 statp->retrans = RES_MAXRETRANS;
 465                 } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
 466                         i = atoi(cp + sizeof("attempts:") - 1);
 467                         if (i <= RES_MAXRETRY)
 468                                 statp->retry = i;
 469                         else
 470                                 statp->retry = RES_MAXRETRY;
 471                 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
 472 #ifdef DEBUG
 473                         if (!(statp->options & RES_DEBUG)) {
 474                                 printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 475                                        options, source);
 476                                 statp->options |= RES_DEBUG;
 477                         }
 478                         printf(";;\tdebug\n");
 479 #endif
 480                 } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
 481                         statp->options |= RES_USE_INET6;
 482                 } else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
 483                         statp->options |= RES_ROTATE;
 484                 } else if (!strncmp(cp, "no-check-names",
 485                                     sizeof("no-check-names") - 1)) {
 486                         statp->options |= RES_NOCHECKNAME;
 487                 } else {
 488                         /* XXX - print a warning here? */
 489                 }
 490                 /* skip to next run of spaces */
 491                 while (*cp && *cp != ' ' && *cp != '\t')
 492                         cp++;
 493         }
 494 }
 495
 496 #ifdef RESOLVSORT
 497 /* XXX - should really support CIDR which means explicit masks always. */
 498 static u_int32_t
 499 net_mask(in)            /* XXX - should really use system's version of this */
 500         struct in_addr in;
 501 {
 502         register u_int32_t i = ntohl(in.s_addr);
 503
 504         if (IN_CLASSA(i))
 505                 return (htonl(IN_CLASSA_NET));
 506         else if (IN_CLASSB(i))
 507                 return (htonl(IN_CLASSB_NET));
 508         return (htonl(IN_CLASSC_NET));
 509 }
 510 #endif
 511
 512 u_int
 513 res_randomid(void) {
 514         struct timeval now;
 515
 516         __gettimeofday(&now, NULL);
 517         return (0xffff & (now.tv_sec ^ now.tv_usec ^ __getpid()));
 518 }
 519
 520 /*
 521  * This routine is for closing the socket if a virtual circuit is used and
 522  * the program wants to close it.  This provides support for endhostent()
 523  * which expects to close the socket.
 524  *
 525  * This routine is not expected to be user visible.
 526  */
 527 void
 528 res_nclose(res_state statp) {
 529         int ns;
 530
 531         if (statp->_vcsock >= 0) {
 532                 (void) __close(statp->_vcsock);
 533                 statp->_vcsock = -1;
 534                 statp->_flags &= ~(RES_F_VC | RES_F_CONN);
 535         }
 536 #ifdef _LIBC
 537         for (ns = 0; ns < statp->_u._ext.nscount + statp->_u._ext.nscount6;
 538              ns++)
 539 #else
 540         for (ns = 0; ns < statp->_u._ext.nscount; ns++)
 541 #endif
 542         {
 543                 if (statp->_u._ext.nssocks[ns] != -1) {
 544                         (void) __close(statp->_u._ext.nssocks[ns]);
 545                         statp->_u._ext.nssocks[ns] = -1;
 546                 }
 547         }
 548         statp->_u._ext.nsinit = 0;
 549 }