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         int haveenv = 0;
 147         int havesearch = 0;
 148 #ifdef RESOLVSORT
 149         int nsort = 0;
 150         char *net;
 151 #endif
 152 #ifndef RFC1535
 153         int dots;
 154 #endif
 155
 156         if (!preinit) {
 157                 statp->retrans = RES_TIMEOUT;
 158                 statp->retry = RES_DFLRETRY;
 159                 statp->options = RES_DEFAULT;
 160                 statp->id = res_randomid();
 161         }
 162
 163 #ifdef USELOOPBACK
 164         statp->nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
 165 #else
 166         statp->nsaddr.sin_addr.s_addr = INADDR_ANY;
 167 #endif
 168         statp->nsaddr.sin_family = AF_INET;
 169         statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
 170         statp->nscount = 1;
 171         statp->ndots = 1;
 172         statp->pfcode = 0;
 173         statp->_vcsock = -1;
 174         statp->_flags = 0;
 175         statp->qhook = NULL;
 176         statp->rhook = NULL;
 177         statp->_u._ext.nscount = 0;
 178
 179         /* Allow user to override the local domain definition */
 180         if ((cp = __secure_getenv("LOCALDOMAIN")) != NULL) {
 181                 (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 182                 statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 183                 haveenv++;
 184
 185                 /*
 186                  * Set search list to be blank-separated strings
 187                  * from rest of env value.  Permits users of LOCALDOMAIN
 188                  * to still have a search list, and anyone to set the
 189                  * one that they want to use as an individual (even more
 190                  * important now that the rfc1535 stuff restricts searches)
 191                  */
 192                 cp = statp->defdname;
 193                 pp = statp->dnsrch;
 194                 *pp++ = cp;
 195                 for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 196                         if (*cp == '\n')        /* silly backwards compat */
 197                                 break;
 198                         else if (*cp == ' ' || *cp == '\t') {
 199                                 *cp = 0;
 200                                 n = 1;
 201                         } else if (n) {
 202                                 *pp++ = cp;
 203                                 n = 0;
 204                                 havesearch = 1;
 205                         }
 206                 }
 207                 /* null terminate last domain if there are excess */
 208                 while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
 209                         cp++;
 210                 *cp = '\0';
 211                 *pp++ = 0;
 212         }
 213
 214 #define MATCH(line, name) \
 215         (!strncmp(line, name, sizeof(name) - 1) && \
 216         (line[sizeof(name) - 1] == ' ' || \
 217          line[sizeof(name) - 1] == '\t'))
 218
 219         if ((fp = fopen(_PATH_RESCONF, "r")) != NULL) {
 220             /* read the config file */
 221             while (fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
 222                 /* skip comments */
 223                 if (*buf == ';' || *buf == '#')
 224                         continue;
 225                 /* read default domain name */
 226                 if (MATCH(buf, "domain")) {
 227                     if (haveenv)        /* skip if have from environ */
 228                             continue;
 229                     cp = buf + sizeof("domain") - 1;
 230                     while (*cp == ' ' || *cp == '\t')
 231                             cp++;
 232                     if ((*cp == '\0') || (*cp == '\n'))
 233                             continue;
 234                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 235                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 236                     if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
 237                             *cp = '\0';
 238                     havesearch = 0;
 239                     continue;
 240                 }
 241                 /* set search list */
 242                 if (MATCH(buf, "search")) {
 243                     if (haveenv)        /* skip if have from environ */
 244                             continue;
 245                     cp = buf + sizeof("search") - 1;
 246                     while (*cp == ' ' || *cp == '\t')
 247                             cp++;
 248                     if ((*cp == '\0') || (*cp == '\n'))
 249                             continue;
 250                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 251                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 252                     if ((cp = strchr(statp->defdname, '\n')) != NULL)
 253                             *cp = '\0';
 254                     /*
 255                      * Set search list to be blank-separated strings
 256                      * on rest of line.
 257                      */
 258                     cp = statp->defdname;
 259                     pp = statp->dnsrch;
 260                     *pp++ = cp;
 261                     for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 262                             if (*cp == ' ' || *cp == '\t') {
 263                                     *cp = 0;
 264                                     n = 1;
 265                             } else if (n) {
 266                                     *pp++ = cp;
 267                                     n = 0;
 268                             }
 269                     }
 270                     /* null terminate last domain if there are excess */
 271                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 272                             cp++;
 273                     *cp = '\0';
 274                     *pp++ = 0;
 275                     havesearch = 1;
 276                     continue;
 277                 }
 278                 /* read nameservers to query */
 279                 if (MATCH(buf, "nameserver") && nserv < MAXNS) {
 280                     struct in_addr a;
 281
 282                     cp = buf + sizeof("nameserver") - 1;
 283                     while (*cp == ' ' || *cp == '\t')
 284                         cp++;
 285                     if ((*cp != '\0') && (*cp != '\n') && inet_aton(cp, &a)) {
 286                         statp->nsaddr_list[nserv].sin_addr = a;
 287                         statp->nsaddr_list[nserv].sin_family = AF_INET;
 288                         statp->nsaddr_list[nserv].sin_port =
 289                                 htons(NAMESERVER_PORT);
 290                         nserv++;
 291                     }
 292                     continue;
 293                 }
 294 #ifdef RESOLVSORT
 295                 if (MATCH(buf, "sortlist")) {
 296                     struct in_addr a;
 297
 298                     cp = buf + sizeof("sortlist") - 1;
 299                     while (nsort < MAXRESOLVSORT) {
 300                         while (*cp == ' ' || *cp == '\t')
 301                             cp++;
 302                         if (*cp == '\0' || *cp == '\n' || *cp == ';')
 303                             break;
 304                         net = cp;
 305                         while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
 306                                isascii(*cp) && !isspace(*cp))
 307                                 cp++;
 308                         n = *cp;
 309                         *cp = 0;
 310                         if (inet_aton(net, &a)) {
 311                             statp->sort_list[nsort].addr = a;
 312                             if (ISSORTMASK(n)) {
 313                                 *cp++ = n;
 314                                 net = cp;
 315                                 while (*cp && *cp != ';' &&
 316                                         isascii(*cp) && !isspace(*cp))
 317                                     cp++;
 318                                 n = *cp;
 319                                 *cp = 0;
 320                                 if (inet_aton(net, &a)) {
 321                                     statp->sort_list[nsort].mask = a.s_addr;
 322                                 } else {
 323                                     statp->sort_list[nsort].mask =
 324                                         net_mask(statp->sort_list[nsort].addr);
 325                                 }
 326                             } else {
 327                                 statp->sort_list[nsort].mask =
 328                                     net_mask(statp->sort_list[nsort].addr);
 329                             }
 330                             nsort++;
 331                         }
 332                         *cp = n;
 333                     }
 334                     continue;
 335                 }
 336 #endif
 337                 if (MATCH(buf, "options")) {
 338                     res_setoptions(statp, buf + sizeof("options") - 1, "conf");
 339                     continue;
 340                 }
 341             }
 342             if (nserv > 1)
 343                 statp->nscount = nserv;
 344 #ifdef RESOLVSORT
 345             statp->nsort = nsort;
 346 #endif
 347             (void) fclose(fp);
 348         }
 349         if (statp->defdname[0] == 0 &&
 350             __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
 351             (cp = strchr(buf, '.')) != NULL)
 352                 strcpy(statp->defdname, cp + 1);
 353
 354         /* find components of local domain that might be searched */
 355         if (havesearch == 0) {
 356                 pp = statp->dnsrch;
 357                 *pp++ = statp->defdname;
 358                 *pp = NULL;
 359
 360 #ifndef RFC1535
 361                 dots = 0;
 362                 for (cp = statp->defdname; *cp; cp++)
 363                         dots += (*cp == '.');
 364
 365                 cp = statp->defdname;
 366                 while (pp < statp->dnsrch + MAXDFLSRCH) {
 367                         if (dots < LOCALDOMAINPARTS)
 368                                 break;
 369                         cp = __rawmemchr(cp, '.') + 1;    /* we know there is one */
 370                         *pp++ = cp;
 371                         dots--;
 372                 }
 373                 *pp = NULL;
 374 #ifdef DEBUG
 375                 if (statp->options & RES_DEBUG) {
 376                         printf(";; res_init()... default dnsrch list:\n");
 377                         for (pp = statp->dnsrch; *pp; pp++)
 378                                 printf(";;\t%s\n", *pp);
 379                         printf(";;\t..END..\n");
 380                 }
 381 #endif
 382 #endif /* !RFC1535 */
 383         }
 384
 385         if ((cp = __secure_getenv("RES_OPTIONS")) != NULL)
 386                 res_setoptions(statp, cp, "env");
 387         statp->options |= RES_INIT;
 388         return (0);
 389 }
 390
 391 static void
 392 internal_function
 393 res_setoptions(res_state statp, const char *options, const char *source) {
 394         const char *cp = options;
 395         int i;
 396
 397 #ifdef DEBUG
 398         if (statp->options & RES_DEBUG)
 399                 printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 400                        options, source);
 401 #endif
 402         while (*cp) {
 403                 /* skip leading and inner runs of spaces */
 404                 while (*cp == ' ' || *cp == '\t')
 405                         cp++;
 406                 /* search for and process individual options */
 407                 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
 408                         i = atoi(cp + sizeof("ndots:") - 1);
 409                         if (i <= RES_MAXNDOTS)
 410                                 statp->ndots = i;
 411                         else
 412                                 statp->ndots = RES_MAXNDOTS;
 413 #ifdef DEBUG
 414                         if (statp->options & RES_DEBUG)
 415                                 printf(";;\tndots=%d\n", statp->ndots);
 416 #endif
 417                 } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 418                         i = atoi(cp + sizeof("timeout:") - 1);
 419                         if (i <= RES_MAXRETRANS)
 420                                 statp->retrans = i;
 421                         else
 422                                 statp->retrans = RES_MAXRETRANS;
 423                 } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
 424                         i = atoi(cp + sizeof("attempts:") - 1);
 425                         if (i <= RES_MAXRETRY)
 426                                 statp->retry = i;
 427                         else
 428                                 statp->retry = RES_MAXRETRY;
 429                 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
 430 #ifdef DEBUG
 431                         if (!(statp->options & RES_DEBUG)) {
 432                                 printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 433                                        options, source);
 434                                 statp->options |= RES_DEBUG;
 435                         }
 436                         printf(";;\tdebug\n");
 437 #endif
 438                 } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
 439                         statp->options |= RES_USE_INET6;
 440                 } else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
 441                         statp->options |= RES_ROTATE;
 442                 } else if (!strncmp(cp, "no-check-names",
 443                                     sizeof("no-check-names") - 1)) {
 444                         statp->options |= RES_NOCHECKNAME;
 445                 } else {
 446                         /* XXX - print a warning here? */
 447                 }
 448                 /* skip to next run of spaces */
 449                 while (*cp && *cp != ' ' && *cp != '\t')
 450                         cp++;
 451         }
 452 }
 453
 454 #ifdef RESOLVSORT
 455 /* XXX - should really support CIDR which means explicit masks always. */
 456 static u_int32_t
 457 net_mask(in)            /* XXX - should really use system's version of this */
 458         struct in_addr in;
 459 {
 460         register u_int32_t i = ntohl(in.s_addr);
 461
 462         if (IN_CLASSA(i))
 463                 return (htonl(IN_CLASSA_NET));
 464         else if (IN_CLASSB(i))
 465                 return (htonl(IN_CLASSB_NET));
 466         return (htonl(IN_CLASSC_NET));
 467 }
 468 #endif
 469
 470 u_int
 471 res_randomid(void) {
 472         struct timeval now;
 473
 474         __gettimeofday(&now, NULL);
 475         return (0xffff & (now.tv_sec ^ now.tv_usec ^ __getpid()));
 476 }
 477
 478 /*
 479  * This routine is for closing the socket if a virtual circuit is used and
 480  * the program wants to close it.  This provides support for endhostent()
 481  * which expects to close the socket.
 482  *
 483  * This routine is not expected to be user visible.
 484  */
 485 void
 486 res_nclose(res_state statp) {
 487         int ns;
 488
 489         if (statp->_vcsock >= 0) {
 490                 (void) close(statp->_vcsock);
 491                 statp->_vcsock = -1;
 492                 statp->_flags &= ~(RES_F_VC | RES_F_CONN);
 493         }
 494         for (ns = 0; ns < statp->_u._ext.nscount; ns++) {
 495                 if (statp->_u._ext.nssocks[ns] != -1) {
 496                         (void) close(statp->_u._ext.nssocks[ns]);
 497                         statp->_u._ext.nssocks[ns] = -1;
 498                 }
 499         }
 500         statp->_u._ext.nscount = 0;
 501 }