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 <stdio_ext.h>
  85 #include <stdlib.h>
  86 #include <string.h>
  87 #include <unistd.h>
  88
  89 #include <not-cancel.h>
  90
  91 /* Options.  Should all be left alone. */
  92 #define RESOLVSORT
  93 #define RFC1535
  94 /* #undef DEBUG */
  95
  96 static void res_setoptions (res_state, const char *, const char *)
  97      internal_function;
  98
  99 #ifdef RESOLVSORT
 100 static const char sort_mask_chars[] = "/&";
 101 #define ISSORTMASK(ch) (strchr(sort_mask_chars, ch) != NULL)
 102 static u_int32_t net_mask (struct in_addr) __THROW;
 103 #endif
 104
 105 #if !defined(isascii)   /* XXX - could be a function */
 106 # define isascii(c) (!(c & 0200))
 107 #endif
 108
 109 #ifdef _LIBC
 110 unsigned long long int __res_initstamp attribute_hidden;
 111 #endif
 112
 113 /*
 114  * Resolver state default settings.
 115  */
 116
 117 /*
 118  * Set up default settings.  If the configuration file exist, the values
 119  * there will have precedence.  Otherwise, the server address is set to
 120  * INADDR_ANY and the default domain name comes from the gethostname().
 121  *
 122  * An interrim version of this code (BIND 4.9, pre-4.4BSD) used 127.0.0.1
 123  * rather than INADDR_ANY ("0.0.0.0") as the default name server address
 124  * since it was noted that INADDR_ANY actually meant ``the first interface
 125  * you "ifconfig"'d at boot time'' and if this was a SLIP or PPP interface,
 126  * it had to be "up" in order for you to reach your own name server.  It
 127  * was later decided that since the recommended practice is to always
 128  * install local static routes through 127.0.0.1 for all your network
 129  * interfaces, that we could solve this problem without a code change.
 130  *
 131  * The configuration file should always be used, since it is the only way
 132  * to specify a default domain.  If you are running a server on your local
 133  * machine, you should say "nameserver 0.0.0.0" or "nameserver 127.0.0.1"
 134  * in the configuration file.
 135  *
 136  * Return 0 if completes successfully, -1 on error
 137  */
 138 int
 139 res_ninit(res_state statp) {
 140         extern int __res_vinit(res_state, int);
 141
 142         return (__res_vinit(statp, 0));
 143 }
 144 #ifdef _LIBC
 145 libc_hidden_def (__res_ninit)
 146 #endif
 147
 148 /* This function has to be reachable by res_data.c but not publically. */
 149 int
 150 __res_vinit(res_state statp, int preinit) {
 151         register FILE *fp;
 152         register char *cp, **pp;
 153         register int n;
 154         char buf[BUFSIZ];
 155         int nserv = 0;    /* number of nameserver records read from file */
 156 #ifdef _LIBC
 157         int nservall = 0; /* number of NS records read, nserv IPv4 only */
 158 #endif
 159         int haveenv = 0;
 160         int havesearch = 0;
 161 #ifdef RESOLVSORT
 162         int nsort = 0;
 163         char *net;
 164 #endif
 165 #ifndef RFC1535
 166         int dots;
 167 #endif
 168 #ifdef _LIBC
 169         statp->_u._ext.initstamp = __res_initstamp;
 170 #endif
 171
 172         if (!preinit) {
 173                 statp->retrans = RES_TIMEOUT;
 174                 statp->retry = RES_DFLRETRY;
 175                 statp->options = RES_DEFAULT;
 176                 statp->id = res_randomid();
 177         }
 178
 179 #ifdef USELOOPBACK
 180         statp->nsaddr.sin_addr = inet_makeaddr(IN_LOOPBACKNET, 1);
 181 #else
 182         statp->nsaddr.sin_addr.s_addr = INADDR_ANY;
 183 #endif
 184         statp->nsaddr.sin_family = AF_INET;
 185         statp->nsaddr.sin_port = htons(NAMESERVER_PORT);
 186         statp->nscount = 1;
 187         statp->ndots = 1;
 188         statp->pfcode = 0;
 189         statp->_vcsock = -1;
 190         statp->_flags = 0;
 191         statp->qhook = NULL;
 192         statp->rhook = NULL;
 193         statp->_u._ext.nsinit = 0;
 194         statp->_u._ext.nscount = 0;
 195 #ifdef _LIBC
 196         statp->_u._ext.nscount6 = 0;
 197         for (n = 0; n < MAXNS; n++) {
 198                 statp->_u._ext.nsaddrs[n] = NULL;
 199                 statp->_u._ext.nsmap[n] = MAXNS;
 200         }
 201 #endif
 202
 203         /* Allow user to override the local domain definition */
 204         if ((cp = getenv("LOCALDOMAIN")) != NULL) {
 205                 (void)strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 206                 statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 207                 haveenv++;
 208
 209                 /*
 210                  * Set search list to be blank-separated strings
 211                  * from rest of env value.  Permits users of LOCALDOMAIN
 212                  * to still have a search list, and anyone to set the
 213                  * one that they want to use as an individual (even more
 214                  * important now that the rfc1535 stuff restricts searches)
 215                  */
 216                 cp = statp->defdname;
 217                 pp = statp->dnsrch;
 218                 *pp++ = cp;
 219                 for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 220                         if (*cp == '\n')        /* silly backwards compat */
 221                                 break;
 222                         else if (*cp == ' ' || *cp == '\t') {
 223                                 *cp = 0;
 224                                 n = 1;
 225                         } else if (n) {
 226                                 *pp++ = cp;
 227                                 n = 0;
 228                                 havesearch = 1;
 229                         }
 230                 }
 231                 /* null terminate last domain if there are excess */
 232                 while (*cp != '\0' && *cp != ' ' && *cp != '\t' && *cp != '\n')
 233                         cp++;
 234                 *cp = '\0';
 235                 *pp++ = 0;
 236         }
 237
 238 #define MATCH(line, name) \
 239         (!strncmp(line, name, sizeof(name) - 1) && \
 240         (line[sizeof(name) - 1] == ' ' || \
 241          line[sizeof(name) - 1] == '\t'))
 242
 243         if ((fp = fopen(_PATH_RESCONF, "rc")) != NULL) {
 244                 /* No threads use this stream.  */
 245                 __fsetlocking (fp, FSETLOCKING_BYCALLER);
 246             /* read the config file */
 247             while (fgets_unlocked(buf, sizeof(buf), fp) != NULL) {
 248                 /* skip comments */
 249                 if (*buf == ';' || *buf == '#')
 250                         continue;
 251                 /* read default domain name */
 252                 if (MATCH(buf, "domain")) {
 253                     if (haveenv)        /* skip if have from environ */
 254                             continue;
 255                     cp = buf + sizeof("domain") - 1;
 256                     while (*cp == ' ' || *cp == '\t')
 257                             cp++;
 258                     if ((*cp == '\0') || (*cp == '\n'))
 259                             continue;
 260                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 261                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 262                     if ((cp = strpbrk(statp->defdname, " \t\n")) != NULL)
 263                             *cp = '\0';
 264                     havesearch = 0;
 265                     continue;
 266                 }
 267                 /* set search list */
 268                 if (MATCH(buf, "search")) {
 269                     if (haveenv)        /* skip if have from environ */
 270                             continue;
 271                     cp = buf + sizeof("search") - 1;
 272                     while (*cp == ' ' || *cp == '\t')
 273                             cp++;
 274                     if ((*cp == '\0') || (*cp == '\n'))
 275                             continue;
 276                     strncpy(statp->defdname, cp, sizeof(statp->defdname) - 1);
 277                     statp->defdname[sizeof(statp->defdname) - 1] = '\0';
 278                     if ((cp = strchr(statp->defdname, '\n')) != NULL)
 279                             *cp = '\0';
 280                     /*
 281                      * Set search list to be blank-separated strings
 282                      * on rest of line.
 283                      */
 284                     cp = statp->defdname;
 285                     pp = statp->dnsrch;
 286                     *pp++ = cp;
 287                     for (n = 0; *cp && pp < statp->dnsrch + MAXDNSRCH; cp++) {
 288                             if (*cp == ' ' || *cp == '\t') {
 289                                     *cp = 0;
 290                                     n = 1;
 291                             } else if (n) {
 292                                     *pp++ = cp;
 293                                     n = 0;
 294                             }
 295                     }
 296                     /* null terminate last domain if there are excess */
 297                     while (*cp != '\0' && *cp != ' ' && *cp != '\t')
 298                             cp++;
 299                     *cp = '\0';
 300                     *pp++ = 0;
 301                     havesearch = 1;
 302                     continue;
 303                 }
 304                 /* read nameservers to query */
 305 #ifdef _LIBC
 306                 if (MATCH(buf, "nameserver") && nservall < MAXNS) {
 307 #else
 308                 if (MATCH(buf, "nameserver") && nserv < MAXNS) {
 309 #endif
 310                     struct in_addr a;
 311
 312                     cp = buf + sizeof("nameserver") - 1;
 313                     while (*cp == ' ' || *cp == '\t')
 314                         cp++;
 315                     if ((*cp != '\0') && (*cp != '\n')
 316                         && __inet_aton(cp, &a)) {
 317                         statp->nsaddr_list[nserv].sin_addr = a;
 318                         statp->nsaddr_list[nserv].sin_family = AF_INET;
 319                         statp->nsaddr_list[nserv].sin_port =
 320                                 htons(NAMESERVER_PORT);
 321                         nserv++;
 322 #ifdef _LIBC
 323                         nservall++;
 324                     } else {
 325                         struct in6_addr a6;
 326                         char *el;
 327
 328                         if ((el = strchr(cp, '\n')) != NULL)
 329                             *el = '\0';
 330                         if ((*cp != '\0') &&
 331                             (inet_pton(AF_INET6, cp, &a6) > 0)) {
 332                             struct sockaddr_in6 *sa6;
 333
 334                             sa6 = malloc(sizeof(*sa6));
 335                             if (sa6 != NULL) {
 336                                 sa6->sin6_addr = a6;
 337                                 sa6->sin6_family = AF_INET6;
 338                                 sa6->sin6_port = htons(NAMESERVER_PORT);
 339                                 statp->_u._ext.nsaddrs[nservall] = sa6;
 340                                 statp->_u._ext.nssocks[nservall] = -1;
 341                                 statp->_u._ext.nsmap[nservall] = MAXNS + 1;
 342                                 nservall++;
 343                             }
 344                         }
 345 #endif
 346                     }
 347                     continue;
 348                 }
 349 #ifdef RESOLVSORT
 350                 if (MATCH(buf, "sortlist")) {
 351                     struct in_addr a;
 352
 353                     cp = buf + sizeof("sortlist") - 1;
 354                     while (nsort < MAXRESOLVSORT) {
 355                         while (*cp == ' ' || *cp == '\t')
 356                             cp++;
 357                         if (*cp == '\0' || *cp == '\n' || *cp == ';')
 358                             break;
 359                         net = cp;
 360                         while (*cp && !ISSORTMASK(*cp) && *cp != ';' &&
 361                                isascii(*cp) && !isspace(*cp))
 362                                 cp++;
 363                         n = *cp;
 364                         *cp = 0;
 365                         if (__inet_aton(net, &a)) {
 366                             statp->sort_list[nsort].addr = a;
 367                             if (ISSORTMASK(n)) {
 368                                 *cp++ = n;
 369                                 net = cp;
 370                                 while (*cp && *cp != ';' &&
 371                                         isascii(*cp) && !isspace(*cp))
 372                                     cp++;
 373                                 n = *cp;
 374                                 *cp = 0;
 375                                 if (__inet_aton(net, &a)) {
 376                                     statp->sort_list[nsort].mask = a.s_addr;
 377                                 } else {
 378                                     statp->sort_list[nsort].mask =
 379                                         net_mask(statp->sort_list[nsort].addr);
 380                                 }
 381                             } else {
 382                                 statp->sort_list[nsort].mask =
 383                                     net_mask(statp->sort_list[nsort].addr);
 384                             }
 385                             nsort++;
 386                         }
 387                         *cp = n;
 388                     }
 389                     continue;
 390                 }
 391 #endif
 392                 if (MATCH(buf, "options")) {
 393                     res_setoptions(statp, buf + sizeof("options") - 1, "conf");
 394                     continue;
 395                 }
 396             }
 397             if (nserv > 1)
 398                 statp->nscount = nserv;
 399 #ifdef _LIBC
 400             if (nservall - nserv > 0)
 401                 statp->_u._ext.nscount6 = nservall - nserv;
 402 #endif
 403 #ifdef RESOLVSORT
 404             statp->nsort = nsort;
 405 #endif
 406             (void) fclose(fp);
 407         }
 408         if (statp->defdname[0] == 0 &&
 409             __gethostname(buf, sizeof(statp->defdname) - 1) == 0 &&
 410             (cp = strchr(buf, '.')) != NULL)
 411                 strcpy(statp->defdname, cp + 1);
 412
 413         /* find components of local domain that might be searched */
 414         if (havesearch == 0) {
 415                 pp = statp->dnsrch;
 416                 *pp++ = statp->defdname;
 417                 *pp = NULL;
 418
 419 #ifndef RFC1535
 420                 dots = 0;
 421                 for (cp = statp->defdname; *cp; cp++)
 422                         dots += (*cp == '.');
 423
 424                 cp = statp->defdname;
 425                 while (pp < statp->dnsrch + MAXDFLSRCH) {
 426                         if (dots < LOCALDOMAINPARTS)
 427                                 break;
 428                         cp = __rawmemchr(cp, '.') + 1;    /* we know there is one */
 429                         *pp++ = cp;
 430                         dots--;
 431                 }
 432                 *pp = NULL;
 433 #ifdef DEBUG
 434                 if (statp->options & RES_DEBUG) {
 435                         printf(";; res_init()... default dnsrch list:\n");
 436                         for (pp = statp->dnsrch; *pp; pp++)
 437                                 printf(";;\t%s\n", *pp);
 438                         printf(";;\t..END..\n");
 439                 }
 440 #endif
 441 #endif /* !RFC1535 */
 442         }
 443
 444         if ((cp = getenv("RES_OPTIONS")) != NULL)
 445                 res_setoptions(statp, cp, "env");
 446         statp->options |= RES_INIT;
 447         return (0);
 448 }
 449
 450 static void
 451 internal_function
 452 res_setoptions(res_state statp, const char *options, const char *source) {
 453         const char *cp = options;
 454         int i;
 455
 456 #ifdef DEBUG
 457         if (statp->options & RES_DEBUG)
 458                 printf(";; res_setoptions(\"%s\", \"%s\")...\n",
 459                        options, source);
 460 #endif
 461         while (*cp) {
 462                 /* skip leading and inner runs of spaces */
 463                 while (*cp == ' ' || *cp == '\t')
 464                         cp++;
 465                 /* search for and process individual options */
 466                 if (!strncmp(cp, "ndots:", sizeof("ndots:") - 1)) {
 467                         i = atoi(cp + sizeof("ndots:") - 1);
 468                         if (i <= RES_MAXNDOTS)
 469                                 statp->ndots = i;
 470                         else
 471                                 statp->ndots = RES_MAXNDOTS;
 472 #ifdef DEBUG
 473                         if (statp->options & RES_DEBUG)
 474                                 printf(";;\tndots=%d\n", statp->ndots);
 475 #endif
 476                 } else if (!strncmp(cp, "timeout:", sizeof("timeout:") - 1)) {
 477                         i = atoi(cp + sizeof("timeout:") - 1);
 478                         if (i <= RES_MAXRETRANS)
 479                                 statp->retrans = i;
 480                         else
 481                                 statp->retrans = RES_MAXRETRANS;
 482                 } else if (!strncmp(cp, "attempts:", sizeof("attempts:") - 1)){
 483                         i = atoi(cp + sizeof("attempts:") - 1);
 484                         if (i <= RES_MAXRETRY)
 485                                 statp->retry = i;
 486                         else
 487                                 statp->retry = RES_MAXRETRY;
 488                 } else if (!strncmp(cp, "debug", sizeof("debug") - 1)) {
 489 #ifdef DEBUG
 490                         if (!(statp->options & RES_DEBUG)) {
 491                                 printf(";; res_setoptions(\"%s\", \"%s\")..\n",
 492                                        options, source);
 493                                 statp->options |= RES_DEBUG;
 494                         }
 495                         printf(";;\tdebug\n");
 496 #endif
 497                 } else if (!strncmp(cp, "inet6", sizeof("inet6") - 1)) {
 498                         statp->options |= RES_USE_INET6;
 499                 } else if (!strncmp(cp, "ip6-bytestring",
 500                                     sizeof("ip6-bytestring") - 1)) {
 501                         statp->options |= RES_USEBSTRING;
 502                 } else if (!strncmp(cp, "no-ip6-dotint",
 503                                     sizeof("no-ip6-dotint") - 1)) {
 504                         statp->options |= RES_NOIP6DOTINT;
 505                 } else if (!strncmp(cp, "ip6-dotint",
 506                                     sizeof("ip6-dotint") - 1)) {
 507                         statp->options &= ~RES_NOIP6DOTINT;
 508                 } else if (!strncmp(cp, "rotate", sizeof("rotate") - 1)) {
 509                         statp->options |= RES_ROTATE;
 510                 } else if (!strncmp(cp, "no-check-names",
 511                                     sizeof("no-check-names") - 1)) {
 512                         statp->options |= RES_NOCHECKNAME;
 513                 } else {
 514                         /* XXX - print a warning here? */
 515                 }
 516                 /* skip to next run of spaces */
 517                 while (*cp && *cp != ' ' && *cp != '\t')
 518                         cp++;
 519         }
 520 }
 521
 522 #ifdef RESOLVSORT
 523 /* XXX - should really support CIDR which means explicit masks always. */
 524 static u_int32_t
 525 net_mask(in)            /* XXX - should really use system's version of this */
 526         struct in_addr in;
 527 {
 528         register u_int32_t i = ntohl(in.s_addr);
 529
 530         if (IN_CLASSA(i))
 531                 return (htonl(IN_CLASSA_NET));
 532         else if (IN_CLASSB(i))
 533                 return (htonl(IN_CLASSB_NET));
 534         return (htonl(IN_CLASSC_NET));
 535 }
 536 #endif
 537
 538 u_int
 539 res_randomid(void) {
 540         return 0xffff & __getpid();
 541 }
 542 #ifdef _LIBC
 543 libc_hidden_def (__res_randomid)
 544 #endif
 545
 546
 547 /*
 548  * This routine is for closing the socket if a virtual circuit is used and
 549  * the program wants to close it.  This provides support for endhostent()
 550  * which expects to close the socket.
 551  *
 552  * This routine is not expected to be user visible.
 553  */
 554 void
 555 __res_iclose(res_state statp, bool free_addr) {
 556         int ns;
 557
 558         if (statp->_vcsock >= 0) {
 559                 close_not_cancel_no_status(statp->_vcsock);
 560                 statp->_vcsock = -1;
 561                 statp->_flags &= ~(RES_F_VC | RES_F_CONN);
 562         }
 563 #ifdef _LIBC
 564         for (ns = 0; ns < MAXNS; ns++)
 565 #else
 566         for (ns = 0; ns < statp->_u._ext.nscount; ns++)
 567 #endif
 568                 if (statp->_u._ext.nsaddrs[ns]) {
 569                         if (statp->_u._ext.nssocks[ns] != -1) {
 570                                 close_not_cancel_no_status(statp->_u._ext.nssocks[ns]);
 571                                 statp->_u._ext.nssocks[ns] = -1;
 572                         }
 573                         if (free_addr) {
 574                                 free (statp->_u._ext.nsaddrs[ns]);
 575                                 statp->_u._ext.nsaddrs[ns] = NULL;
 576                         }
 577                 }
 578         statp->_u._ext.nsinit = 0;
 579 }
 580 libc_hidden_def (__res_iclose)
 581
 582 void
 583 res_nclose(res_state statp)
 584 {
 585   __res_iclose (statp, true);
 586 }
 587 #ifdef _LIBC
 588 libc_hidden_def (__res_nclose)
 589 #endif
 590
 591 #ifdef _LIBC
 592 # ifdef _LIBC_REENTRANT
 593 /* This is called when a thread is exiting to free resources held in _res.  */
 594 static void __attribute__ ((section ("__libc_thread_freeres_fn")))
 595 res_thread_freeres (void)
 596 {
 597   if (_res.nscount == 0)
 598     /* Never called res_ninit.  */
 599     return;
 600
 601   __res_iclose (&_res, true);           /* Close any VC sockets.  */
 602
 603   /* Make sure we do a full re-initialization the next time.  */
 604   _res.options = 0;
 605 }
 606 text_set_element (__libc_thread_subfreeres, res_thread_freeres);
 607 text_set_element (__libc_subfreeres, res_thread_freeres);
 608 # endif
 609 #endif