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         extern int __res_vinit(res_state, int);
 114
 115         return (__res_vinit(statp, 0));
 116 }
 117 libc_hidden_def (__res_ninit)
 118
 119 /* This function has to be reachable by res_data.c but not publically. */
 120 int
 121 __res_vinit(res_state statp, int preinit) {
 122         FILE *fp;
 123         char *cp, **pp;
 124         int n;
 125         char buf[BUFSIZ];
 126         int nserv = 0;    /* number of nameservers read from file */
 127         int have_serv6 = 0;
 128         int haveenv = 0;
 129         int havesearch = 0;
 130         int nsort = 0;
 131         char *net;
 132         statp->_u._ext.initstamp = __res_initstamp;
 133
 134         if (!preinit) {
 135                 statp->retrans = RES_TIMEOUT;
 136                 statp->retry = RES_DFLRETRY;
 137                 statp->options = RES_DEFAULT;
 138                 statp->id = res_randomid();
 139         }
 140
 141         statp->nscount = 0;
 142         statp->defdname[0] = '\0';
 143         statp->ndots = 1;
 144         statp->pfcode = 0;
 145         statp->_vcsock = -1;
 146         statp->_flags = 0;
 147         statp->__glibc_unused_qhook = NULL;
 148         statp->__glibc_unused_rhook = NULL;
 149         statp->_u._ext.nscount = 0;
 150         for (n = 0; n < MAXNS; n++)
 151             statp->_u._ext.nsaddrs[n] = NULL;
 152
 153         /* Allow user to override the local domain definition */
 154         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 155                 (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 156                 statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 157                 haveenv++;
 158
 159                 /*
 160                  * Set search list to be blank-separated strings
 161                  * from rest of env value.  Permits users of LOCALDOMAIN
 162                  * to still have a search list, and anyone to set the
 163                  * one that they want to use as an individual (even more
 164                  * important now that the rfc1535 stuff restricts searches)
 165                  */
 166                 cp = statp->defdname;
 167                 pp = statp->dnsrch;
 168                 *pp++ = cp;
 169                 for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 170                         if (*cp == '\n')        /* silly backwards compat */
 171                                 break;
 172                         else if (*cp == ' ' || *cp == '\t') {
 173                                 *cp = 0;
 174                                 n = 1;
 175                         } else if (n) {
 176                                 *pp++ = cp;
 177                                 n = 0;
 178                                 havesearch = 1;
 179                         }
 180                 }
 181                 /* null terminate last domain if there are excess */
 182                 while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
 183                         cp++;
 184                 *cp = '\0';
 185                 *pp++ = 0;
 186         }
 187
 188 #define MATCH(line, name) \
 189         (!strncmp(line, name, sizeof(name) - 1) && \
 190         (line[sizeof(name) - 1] == ' ' || \
 191          line[sizeof(name) - 1] == '\t'))
 192
 193         if ((fp = fopen(_PATH_RESCONF, "rce")) != NULL) {
 194             /* No threads use this stream.  */
 195             __fsetlocking (fp, FSETLOCKING_BYCALLER);
 196             /* read the config file */
 197             while (__fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
 198                 /* skip comments */
 199                 if (*buf == ';' || *buf == '#')
 200                         continue;
 201                 /* read default domain name */
 202                 if (MATCH(buf, "domain")) {
 203                     if (haveenv)        /* skip if have from environ */
 204                             continue;
 205                     cp = buf + sizeof("domain") - 1;
 206                     while (*cp == ' ' || *cp == '\t')
 207                             cp++;
 208                     if ((*cp == '\0') || (*cp == '\n'))
 209                             continue;
 210                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 211                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 212                     if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
 213                             *cp = '\0';
 214                     havesearch = 0;
 215                     continue;
 216                 }
 217                 /* set search list */
 218                 if (MATCH(buf, "search")) {
 219                     if (haveenv)        /* skip if have from environ */
 220                             continue;
 221                     cp = buf + sizeof("search") - 1;
 222                     while (*cp == ' ' || *cp == '\t')
 223                             cp++;
 224                     if ((*cp == '\0') || (*cp == '\n'))
 225                             continue;
 226                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 227                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 228                     if ((cp = strchr(statp->defdname, '\n')) != NULL)
 229                             *cp = '\0';
 230                     /*
 231                      * Set search list to be blank-separated strings
 232                      * on rest of line.
 233                      */
 234                     cp = statp->defdname;
 235                     pp = statp->dnsrch;
 236                     *pp++ = cp;
 237                     for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 238                             if (*cp == ' ' || *cp == '\t') {
 239                                     *cp = 0;
 240                                     n = 1;
 241                             } else if (n) {
 242                                     *pp++ = cp;
 243                                     n = 0;
 244                             }
 245                     }
 246                     /* null terminate last domain if there are excess */
 247                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 248                             cp++;
 249                     *cp = '\0';
 250                     *pp++ = 0;
 251                     havesearch = 1;
 252                     continue;
 253                 }
 254                 /* read nameservers to query */
 255                 if (MATCH(buf, "nameserver") && nserv < MAXNS) {
 256                     struct in_addr a;
 257
 258                     cp = buf + sizeof("nameserver") - 1;
 259                     while (*cp == ' ' || *cp == '\t')
 260                         cp++;
 261                     if ((*cp != '\0') && (*cp != '\n')
 262                         && __inet_aton(cp, &a)) {
 263                         statp->nsaddr_list[nserv].sin_addr = a;
 264                         statp->nsaddr_list[nserv].sin_family = AF_INET;
 265                         statp->nsaddr_list[nserv].sin_port =
 266                                 htons(NAMESERVER_PORT);
 267                         nserv++;
 268                     } else {
 269                         struct in6_addr a6;
 270                         char *el;
 271
 272                         if ((el = strpbrk(cp, " \t\n")) != NULL)
 273                             *el = '\0';
 274                         if ((el = strchr(cp, SCOPE_DELIMITER)) != NULL)
 275                             *el = '\0';
 276                         if ((*cp != '\0') &&
 277                             (__inet_pton(AF_INET6, cp, &a6) > 0)) {
 278                             struct sockaddr_in6 *sa6;
 279
 280                             sa6 = malloc(sizeof(*sa6));
 281                             if (sa6 != NULL) {
 282                                 sa6->sin6_family = AF_INET6;
 283                                 sa6->sin6_port = htons(NAMESERVER_PORT);
 284                                 sa6->sin6_flowinfo = 0;
 285                                 sa6->sin6_addr = a6;
 286
 287                                 sa6->sin6_scope_id = 0;
 288                                 if (__glibc_likely (el != NULL)) {
 289                                   /* Ignore errors, for backwards
 290                                      compatibility.  */
 291                                   (void) __inet6_scopeid_pton
 292                                     (&a6, el + 1, &sa6->sin6_scope_id);
 293                                 }
 294
 295                                 statp->nsaddr_list[nserv].sin_family = 0;
 296                                 statp->_u._ext.nsaddrs[nserv] = sa6;
 297                                 statp->_u._ext.nssocks[nserv] = -1;
 298                                 have_serv6 = 1;
 299                                 nserv++;
 300                             }
 301                         }
 302                     }
 303                     continue;
 304                 }
 305                 if (MATCH(buf, "sortlist")) {
 306                     struct in_addr a;
 307
 308                     cp = buf + sizeof("sortlist") - 1;
 309                     while (nsort < MAXRESOLVSORT) {
 310                         while (*cp == ' ' || *cp == '\t')
 311                             cp++;
 312                         if (*cp == '\0' || *cp == '\n' || *cp == ';')
 313                             break;
 314                         net = cp;
 315                         while (*cp && !ISSORTMASK(*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].addr = a;
 322                             if (ISSORTMASK(n)) {
 323                                 *cp++ = n;
 324                                 net = cp;
 325                                 while (*cp && *cp != ';' &&
 326                                         isascii(*cp) && !isspace(*cp))
 327                                     cp++;
 328                                 n = *cp;
 329                                 *cp = 0;
 330                                 if (__inet_aton(net, &a)) {
 331                                     statp->sort_list[nsort].mask = a.s_addr;
 332                                 } else {
 333                                     statp->sort_list[nsort].mask =
 334                                         net_mask(statp->sort_list[nsort].addr);
 335                                 }
 336                             } else {
 337                                 statp->sort_list[nsort].mask =
 338                                     net_mask(statp->sort_list[nsort].addr);
 339                             }
 340                             nsort++;
 341                         }
 342                         *cp = n;
 343                     }
 344                     continue;
 345                 }
 346                 if (MATCH(buf, "options")) {
 347                     res_setoptions(statp, buf + sizeof("options") - 1, "conf");
 348                     continue;
 349                 }
 350             }
 351             statp->nscount = nserv;
 352             if (have_serv6) {
 353                 /* We try IPv6 servers again.  */
 354                 statp->ipv6_unavail = false;
 355             }
 356             statp->nsort = nsort;
 357             (void) fclose(fp);
 358         }
 359         if (__builtin_expect(statp->nscount == 0, 0)) {
 360             statp->nsaddr.sin_addr = __inet_makeaddr(IN_LOOPBACKNET, 1);
 361             statp->nsaddr.sin_family = AF_INET;
 362             statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
 363             statp->nscount = 1;
 364         }
 365         if (statp->defdname[0] == 0 &&
 366             __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
 367             (cp = strchr(buf, '.')) != NULL)
 368                 strcpy(statp->defdname, cp + 1);
 369
 370         /* find components of local domain that might be searched */
 371         if (havesearch == 0) {
 372                 pp = statp->dnsrch;
 373                 *pp++ = statp->defdname;
 374                 *pp = NULL;
 375
 376         }
 377
 378         if ((cp = getenv("RES_OPTIONS")) != NULL)
 379                 res_setoptions(statp, cp, "env");
 380         statp->options |= RES_INIT;
 381         return (0);
 382 }
 383
 384 static void
 385 internal_function
 386 res_setoptions(res_state statp, const char *options, const char *source) {
 387         const char *cp = options;
 388         int i;
 389
 390 #ifdef DEBUG
 391         if (statp->options & RES_DEBUG)
 392                 printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 393                        options, source);
 394 #endif
 395         while (*cp) {
 396                 /* skip leading and inner runs of spaces */
 397                 while (*cp == ' ' || *cp == '\t')
 398                         cp++;
 399                 /* search for and process individual options */
 400                 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
 401                         i = atoi(cp + sizeof("ndots:") - 1);
 402                         if (i <= RES_MAXNDOTS)
 403                                 statp->ndots = i;
 404                         else
 405                                 statp->ndots = RES_MAXNDOTS;
 406 #ifdef DEBUG
 407                         if (statp->options & RES_DEBUG)
 408                                 printf(";;\tndots=%d\n", statp->ndots);
 409 #endif
 410                 } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 411                         i = atoi(cp + sizeof("timeout:") - 1);
 412                         if (i <= RES_MAXRETRANS)
 413                                 statp->retrans = i;
 414                         else
 415                                 statp->retrans = RES_MAXRETRANS;
 416                 } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
 417                         i = atoi(cp + sizeof("attempts:") - 1);
 418                         if (i <= RES_MAXRETRY)
 419                                 statp->retry = i;
 420                         else
 421                                 statp->retry = RES_MAXRETRY;
 422                 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
 423 #ifdef DEBUG
 424                         if (!(statp->options & RES_DEBUG)) {
 425                                 printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 426                                        options, source);
 427                                 statp->options |= RES_DEBUG;
 428                         }
 429                         printf(";;\tdebug\n");
 430 #endif
 431                 } else {
 432                   static const struct
 433                   {
 434                     char str[22];
 435                     uint8_t len;
 436                     uint8_t clear;
 437                     unsigned long int flag;
 438                   } options[] = {
 439 #define STRnLEN(str) str, sizeof (str) - 1
 440                     { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
 441                     { STRnLEN ("rotate"), 0, RES_ROTATE },
 442                     { STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
 443                     { STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
 444                     { STRnLEN ("single-request"), 0, RES_SNGLKUP },
 445                     { STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
 446                     { STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
 447                     { STRnLEN ("use-vc"), 0, RES_USEVC }
 448                   };
 449 #define noptions (sizeof (options) / sizeof (options[0]))
 450                   int i;
 451                   for (i = 0; i < noptions; ++i)
 452                     if (strncmp (cp, options[i].str, options[i].len) == 0)
 453                       {
 454                         if (options[i].clear)
 455                           statp->options &= options[i].flag;
 456                         else
 457                           statp->options |= options[i].flag;
 458                         break;
 459                       }
 460                   if (i == noptions) {
 461                     /* XXX - print a warning here? */
 462                   }
 463                 }
 464                 /* skip to next run of spaces */
 465                 while (*cp && *cp != ' ' && *cp != '\t')
 466                         cp++;
 467         }
 468 }
 469
 470 /* XXX - should really support CIDR which means explicit masks always. */
 471 /* XXX - should really use system's version of this */
 472 static u_int32_t
 473 net_mask (struct in_addr in)
 474 {
 475         u_int32_t i = ntohl(in.s_addr);
 476
 477         if (IN_CLASSA(i))
 478                 return (htonl(IN_CLASSA_NET));
 479         else if (IN_CLASSB(i))
 480                 return (htonl(IN_CLASSB_NET));
 481         return (htonl(IN_CLASSC_NET));
 482 }
 483
 484 u_int
 485 res_randomid(void) {
 486         return 0xffff & __getpid();
 487 }
 488 libc_hidden_def (__res_randomid)
 489
 490
 491 /*
 492  * This routine is for closing the socket if a virtual circuit is used and
 493  * the program wants to close it.  This provides support for endhostent()
 494  * which expects to close the socket.
 495  *
 496  * This routine is not expected to be user visible.
 497  */
 498 void
 499 __res_iclose(res_state statp, bool free_addr) {
 500         int ns;
 501
 502         if (statp->_vcsock >= 0) {
 503                 close_not_cancel_no_status(statp->_vcsock);
 504                 statp->_vcsock = -1;
 505                 statp->_flags &= ~(RES_F_VC | RES_F_CONN);
 506         }
 507         for (ns = 0; ns < statp->nscount; ns++)
 508                 if (statp->_u._ext.nsaddrs[ns]) {
 509                         if (statp->_u._ext.nssocks[ns] != -1) {
 510                                 close_not_cancel_no_status(statp->_u._ext.nssocks[ns]);
 511                                 statp->_u._ext.nssocks[ns] = -1;
 512                         }
 513                         if (free_addr) {
 514                                 free (statp->_u._ext.nsaddrs[ns]);
 515                                 statp->_u._ext.nsaddrs[ns] = NULL;
 516                         }
 517                 }
 518 }
 519 libc_hidden_def (__res_iclose)
 520
 521 void
 522 res_nclose(res_state statp)
 523 {
 524   __res_iclose (statp, true);
 525 }
 526 libc_hidden_def (__res_nclose)
 527
 528 /* This is called when a thread is exiting to free resources held in _res.  */
 529 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
 530 res_thread_freeres (void)
 531 {
 532   if (_res.nscount == 0)
 533     /* Never called res_ninit.  */
 534     return;
 535
 536   __res_iclose (&_res, true);           /* Close any VC sockets.  */
 537
 538   /* Make sure we do a full re-initialization the next time.  */
 539   _res.options = 0;
 540 }
 541 text_set_element (__libc_thread_subfreeres, res_thread_freeres);
 542 text_set_element (__libc_subfreeres, res_thread_freeres);