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 #include <ctype.h>
  68 #include <netdb.h>
  69 #include <resolv/resolv-internal.h>
  70 #include <stdio.h>
  71 #include <stdio_ext.h>
  72 #include <stdlib.h>
  73 #include <string.h>
  74 #include <unistd.h>
  75 #include <stdint.h>
  76 #include <arpa/inet.h>
  77 #include <arpa/nameser.h>
  78 #include <net/if.h>
  79 #include <netinet/in.h>
  80 #include <sys/param.h>
  81 #include <sys/socket.h>
  82 #include <sys/time.h>
  83 #include <sys/types.h>
  84 #include <inet/net-internal.h>
  85
  86 #include <not-cancel.h>
  87
  88 /* Options.  Should all be left alone. */
  89 /* #undef DEBUG */
  90
  91 static void res_setoptions (res_state, const char *, const char *)
  92      internal_function;
  93
  94 static const char sort_mask_chars[] = "/&";
  95 #define ISSORTMASK(ch) (strchr(sort_mask_chars, ch) != NULL)
  96 static u_int32_t net_mask (struct in_addr) __THROW;
  97
  98 unsigned long long int __res_initstamp attribute_hidden;
  99
 100 /*
 101  * Resolver state default settings.
 102  */
 103
 104 /*
 105  * Set up default settings.  If the configuration file exist, the values
 106  * there will have precedence.  Otherwise, the server address is set to
 107  * INADDR_LOOPBACK and the default domain name comes from gethostname.
 108  *
 109  * Return 0 if completes successfully, -1 on error
 110  */
 111 int
 112 res_ninit(res_state statp) {
 113         return (__res_vinit(statp, 0));
 114 }
 115 libc_hidden_def (__res_ninit)
 116
 117 /* This function has to be reachable by res_data.c but not publically. */
 118 int
 119 __res_vinit(res_state statp, int preinit) {
 120         FILE *fp;
 121         char *cp, **pp;
 122         int n;
 123         char buf[BUFSIZ];
 124         int nserv = 0;    /* number of nameservers read from file */
 125         int have_serv6 = 0;
 126         int haveenv = 0;
 127         int havesearch = 0;
 128         int nsort = 0;
 129         char *net;
 130         statp->_u._ext.initstamp = __res_initstamp;
 131
 132         if (!preinit) {
 133                 statp->retrans = RES_TIMEOUT;
 134                 statp->retry = RES_DFLRETRY;
 135                 statp->options = RES_DEFAULT;
 136                 statp->id = res_randomid();
 137         }
 138
 139         statp->nscount = 0;
 140         statp->defdname[0] = '\0';
 141         statp->ndots = 1;
 142         statp->pfcode = 0;
 143         statp->_vcsock = -1;
 144         statp->_flags = 0;
 145         statp->__glibc_unused_qhook = NULL;
 146         statp->__glibc_unused_rhook = NULL;
 147         statp->_u._ext.nscount = 0;
 148         for (n = 0; n < MAXNS; n++)
 149             statp->_u._ext.nsaddrs[n] = NULL;
 150
 151         /* Allow user to override the local domain definition */
 152         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 153                 (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 154                 statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 155                 haveenv++;
 156
 157                 /*
 158                  * Set search list to be blank-separated strings
 159                  * from rest of env value.  Permits users of LOCALDOMAIN
 160                  * to still have a search list, and anyone to set the
 161                  * one that they want to use as an individual (even more
 162                  * important now that the rfc1535 stuff restricts searches)
 163                  */
 164                 cp = statp->defdname;
 165                 pp = statp->dnsrch;
 166                 *pp++ = cp;
 167                 for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 168                         if (*cp == '\n')        /* silly backwards compat */
 169                                 break;
 170                         else if (*cp == ' ' || *cp == '\t') {
 171                                 *cp = 0;
 172                                 n = 1;
 173                         } else if (n) {
 174                                 *pp++ = cp;
 175                                 n = 0;
 176                                 havesearch = 1;
 177                         }
 178                 }
 179                 /* null terminate last domain if there are excess */
 180                 while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
 181                         cp++;
 182                 *cp = '\0';
 183                 *pp++ = 0;
 184         }
 185
 186 #define MATCH(line, name) \
 187         (!strncmp(line, name, sizeof(name) - 1) && \
 188         (line[sizeof(name) - 1] == ' ' || \
 189          line[sizeof(name) - 1] == '\t'))
 190
 191         if ((fp = fopen(_PATH_RESCONF, "rce")) != NULL) {
 192             /* No threads use this stream.  */
 193             __fsetlocking (fp, FSETLOCKING_BYCALLER);
 194             /* read the config file */
 195             while (__fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
 196                 /* skip comments */
 197                 if (*buf == ';' || *buf == '#')
 198                         continue;
 199                 /* read default domain name */
 200                 if (MATCH(buf, "domain")) {
 201                     if (haveenv)        /* skip if have from environ */
 202                             continue;
 203                     cp = buf + sizeof("domain") - 1;
 204                     while (*cp == ' ' || *cp == '\t')
 205                             cp++;
 206                     if ((*cp == '\0') || (*cp == '\n'))
 207                             continue;
 208                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 209                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 210                     if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
 211                             *cp = '\0';
 212                     havesearch = 0;
 213                     continue;
 214                 }
 215                 /* set search list */
 216                 if (MATCH(buf, "search")) {
 217                     if (haveenv)        /* skip if have from environ */
 218                             continue;
 219                     cp = buf + sizeof("search") - 1;
 220                     while (*cp == ' ' || *cp == '\t')
 221                             cp++;
 222                     if ((*cp == '\0') || (*cp == '\n'))
 223                             continue;
 224                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 225                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 226                     if ((cp = strchr(statp->defdname, '\n')) != NULL)
 227                             *cp = '\0';
 228                     /*
 229                      * Set search list to be blank-separated strings
 230                      * on rest of line.
 231                      */
 232                     cp = statp->defdname;
 233                     pp = statp->dnsrch;
 234                     *pp++ = cp;
 235                     for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 236                             if (*cp == ' ' || *cp == '\t') {
 237                                     *cp = 0;
 238                                     n = 1;
 239                             } else if (n) {
 240                                     *pp++ = cp;
 241                                     n = 0;
 242                             }
 243                     }
 244                     /* null terminate last domain if there are excess */
 245                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 246                             cp++;
 247                     *cp = '\0';
 248                     *pp++ = 0;
 249                     havesearch = 1;
 250                     continue;
 251                 }
 252                 /* read nameservers to query */
 253                 if (MATCH(buf, "nameserver") && nserv < MAXNS) {
 254                     struct in_addr a;
 255
 256                     cp = buf + sizeof("nameserver") - 1;
 257                     while (*cp == ' ' || *cp == '\t')
 258                         cp++;
 259                     if ((*cp != '\0') && (*cp != '\n')
 260                         && __inet_aton(cp, &a)) {
 261                         statp->nsaddr_list[nserv].sin_addr = a;
 262                         statp->nsaddr_list[nserv].sin_family = AF_INET;
 263                         statp->nsaddr_list[nserv].sin_port =
 264                                 htons(NAMESERVER_PORT);
 265                         nserv++;
 266                     } else {
 267                         struct in6_addr a6;
 268                         char *el;
 269
 270                         if ((el = strpbrk(cp, " \t\n")) != NULL)
 271                             *el = '\0';
 272                         if ((el = strchr(cp, SCOPE_DELIMITER)) != NULL)
 273                             *el = '\0';
 274                         if ((*cp != '\0') &&
 275                             (__inet_pton(AF_INET6, cp, &a6) > 0)) {
 276                             struct sockaddr_in6 *sa6;
 277
 278                             sa6 = malloc(sizeof(*sa6));
 279                             if (sa6 != NULL) {
 280                                 sa6->sin6_family = AF_INET6;
 281                                 sa6->sin6_port = htons(NAMESERVER_PORT);
 282                                 sa6->sin6_flowinfo = 0;
 283                                 sa6->sin6_addr = a6;
 284
 285                                 sa6->sin6_scope_id = 0;
 286                                 if (__glibc_likely (el != NULL)) {
 287                                   /* Ignore errors, for backwards
 288                                      compatibility.  */
 289                                   (void) __inet6_scopeid_pton
 290                                     (&a6, el + 1, &sa6->sin6_scope_id);
 291                                 }
 292
 293                                 statp->nsaddr_list[nserv].sin_family = 0;
 294                                 statp->_u._ext.nsaddrs[nserv] = sa6;
 295                                 statp->_u._ext.nssocks[nserv] = -1;
 296                                 have_serv6 = 1;
 297                                 nserv++;
 298                             }
 299                         }
 300                     }
 301                     continue;
 302                 }
 303                 if (MATCH(buf, "sortlist")) {
 304                     struct in_addr a;
 305
 306                     cp = buf + sizeof("sortlist") - 1;
 307                     while (nsort < MAXRESOLVSORT) {
 308                         while (*cp == ' ' || *cp == '\t')
 309                             cp++;
 310                         if (*cp == '\0' || *cp == '\n' || *cp == ';')
 311                             break;
 312                         net = cp;
 313                         while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
 314                                isascii(*cp) && !isspace(*cp))
 315                                 cp++;
 316                         n = *cp;
 317                         *cp = 0;
 318                         if (__inet_aton(net, &a)) {
 319                             statp->sort_list[nsort].addr = a;
 320                             if (ISSORTMASK(n)) {
 321                                 *cp++ = n;
 322                                 net = cp;
 323                                 while (*cp && *cp != ';' &&
 324                                         isascii(*cp) && !isspace(*cp))
 325                                     cp++;
 326                                 n = *cp;
 327                                 *cp = 0;
 328                                 if (__inet_aton(net, &a)) {
 329                                     statp->sort_list[nsort].mask = a.s_addr;
 330                                 } else {
 331                                     statp->sort_list[nsort].mask =
 332                                         net_mask(statp->sort_list[nsort].addr);
 333                                 }
 334                             } else {
 335                                 statp->sort_list[nsort].mask =
 336                                     net_mask(statp->sort_list[nsort].addr);
 337                             }
 338                             nsort++;
 339                         }
 340                         *cp = n;
 341                     }
 342                     continue;
 343                 }
 344                 if (MATCH(buf, "options")) {
 345                     res_setoptions(statp, buf + sizeof("options") - 1, "conf");
 346                     continue;
 347                 }
 348             }
 349             statp->nscount = nserv;
 350             if (have_serv6) {
 351                 /* We try IPv6 servers again.  */
 352                 statp->ipv6_unavail = false;
 353             }
 354             statp->nsort = nsort;
 355             (void) fclose(fp);
 356         }
 357         if (__glibc_unlikely (statp->nscount == 0)) {
 358             statp->nsaddr.sin_addr = __inet_makeaddr(IN_LOOPBACKNET, 1);
 359             statp->nsaddr.sin_family = AF_INET;
 360             statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
 361             statp->nscount = 1;
 362         }
 363         if (statp->defdname[0] == 0 &&
 364             __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
 365             (cp = strchr(buf, '.')) != NULL)
 366                 strcpy(statp->defdname, cp + 1);
 367
 368         /* find components of local domain that might be searched */
 369         if (havesearch == 0) {
 370                 pp = statp->dnsrch;
 371                 *pp++ = statp->defdname;
 372                 *pp = NULL;
 373
 374         }
 375
 376         if ((cp = getenv("RES_OPTIONS")) != NULL)
 377                 res_setoptions(statp, cp, "env");
 378         statp->options |= RES_INIT;
 379         return (0);
 380 }
 381
 382 static void
 383 internal_function
 384 res_setoptions(res_state statp, const char *options, const char *source) {
 385         const char *cp = options;
 386         int i;
 387
 388 #ifdef DEBUG
 389         if (statp->options & RES_DEBUG)
 390                 printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 391                        options, source);
 392 #endif
 393         while (*cp) {
 394                 /* skip leading and inner runs of spaces */
 395                 while (*cp == ' ' || *cp == '\t')
 396                         cp++;
 397                 /* search for and process individual options */
 398                 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
 399                         i = atoi(cp + sizeof("ndots:") - 1);
 400                         if (i <= RES_MAXNDOTS)
 401                                 statp->ndots = i;
 402                         else
 403                                 statp->ndots = RES_MAXNDOTS;
 404 #ifdef DEBUG
 405                         if (statp->options & RES_DEBUG)
 406                                 printf(";;\tndots=%d\n", statp->ndots);
 407 #endif
 408                 } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 409                         i = atoi(cp + sizeof("timeout:") - 1);
 410                         if (i <= RES_MAXRETRANS)
 411                                 statp->retrans = i;
 412                         else
 413                                 statp->retrans = RES_MAXRETRANS;
 414                 } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
 415                         i = atoi(cp + sizeof("attempts:") - 1);
 416                         if (i <= RES_MAXRETRY)
 417                                 statp->retry = i;
 418                         else
 419                                 statp->retry = RES_MAXRETRY;
 420                 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
 421 #ifdef DEBUG
 422                         if (!(statp->options & RES_DEBUG)) {
 423                                 printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 424                                        options, source);
 425                                 statp->options |= RES_DEBUG;
 426                         }
 427                         printf(";;\tdebug\n");
 428 #endif
 429                 } else {
 430                   static const struct
 431                   {
 432                     char str[22];
 433                     uint8_t len;
 434                     uint8_t clear;
 435                     unsigned long int flag;
 436                   } options[] = {
 437 #define STRnLEN(str) str, sizeof (str) - 1
 438                     { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
 439                     { STRnLEN ("rotate"), 0, RES_ROTATE },
 440                     { STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
 441                     { STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
 442                     { STRnLEN ("single-request"), 0, RES_SNGLKUP },
 443                     { STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
 444                     { STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
 445                     { STRnLEN ("use-vc"), 0, RES_USEVC }
 446                   };
 447 #define noptions (sizeof (options) / sizeof (options[0]))
 448                   int i;
 449                   for (i = 0; i < noptions; ++i)
 450                     if (strncmp (cp, options[i].str, options[i].len) == 0)
 451                       {
 452                         if (options[i].clear)
 453                           statp->options &= options[i].flag;
 454                         else
 455                           statp->options |= options[i].flag;
 456                         break;
 457                       }
 458                   if (i == noptions) {
 459                     /* XXX - print a warning here? */
 460                   }
 461                 }
 462                 /* skip to next run of spaces */
 463                 while (*cp && *cp != ' ' && *cp != '\t')
 464                         cp++;
 465         }
 466 }
 467
 468 /* XXX - should really support CIDR which means explicit masks always. */
 469 /* XXX - should really use system's version of this */
 470 static u_int32_t
 471 net_mask (struct in_addr in)
 472 {
 473         u_int32_t i = ntohl(in.s_addr);
 474
 475         if (IN_CLASSA(i))
 476                 return (htonl(IN_CLASSA_NET));
 477         else if (IN_CLASSB(i))
 478                 return (htonl(IN_CLASSB_NET));
 479         return (htonl(IN_CLASSC_NET));
 480 }
 481
 482 /*
 483  * This routine is for closing the socket if a virtual circuit is used and
 484  * the program wants to close it.  This provides support for endhostent()
 485  * which expects to close the socket.
 486  *
 487  * This routine is not expected to be user visible.
 488  */
 489 void
 490 __res_iclose(res_state statp, bool free_addr) {
 491         int ns;
 492
 493         if (statp->_vcsock >= 0) {
 494                 close_not_cancel_no_status(statp->_vcsock);
 495                 statp->_vcsock = -1;
 496                 statp->_flags &= ~(RES_F_VC | RES_F_CONN);
 497         }
 498         for (ns = 0; ns < statp->nscount; ns++)
 499                 if (statp->_u._ext.nsaddrs[ns]) {
 500                         if (statp->_u._ext.nssocks[ns] != -1) {
 501                                 close_not_cancel_no_status(statp->_u._ext.nssocks[ns]);
 502                                 statp->_u._ext.nssocks[ns] = -1;
 503                         }
 504                         if (free_addr) {
 505                                 free (statp->_u._ext.nsaddrs[ns]);
 506                                 statp->_u._ext.nsaddrs[ns] = NULL;
 507                         }
 508                 }
 509 }
 510 libc_hidden_def (__res_iclose)
 511
 512 void
 513 res_nclose(res_state statp)
 514 {
 515   __res_iclose (statp, true);
 516 }
 517 libc_hidden_def (__res_nclose)
 518
 519 /* This is called when a thread is exiting to free resources held in _res.  */
 520 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
 521 res_thread_freeres (void)
 522 {
 523   if (_res.nscount == 0)
 524     /* Never called res_ninit.  */
 525     return;
 526
 527   __res_iclose (&_res, true);           /* Close any VC sockets.  */
 528
 529   /* Make sure we do a full re-initialization the next time.  */
 530   _res.options = 0;
 531 }
 532 text_set_element (__libc_thread_subfreeres, res_thread_freeres);
 533 text_set_element (__libc_subfreeres, res_thread_freeres);