resolv/res_init.c

   1 /* Resolver state initialization and resolv.conf parsing.
   2    Copyright (C) 1995-2017 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 /*
  20  * Copyright (c) 1985, 1989, 1993
  21  *    The Regents of the University of California.  All rights reserved.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the above copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 4. Neither the name of the University nor the names of its contributors
  32  *    may be used to endorse or promote products derived from this software
  33  *    without specific prior written permission.
  34  *
  35  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  36  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  37  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  38  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  39  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  40  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  41  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  42  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  43  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  44  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  45  * SUCH DAMAGE.
  46  */
  47
  48 /*
  49  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  50  *
  51  * Permission to use, copy, modify, and distribute this software for any
  52  * purpose with or without fee is hereby granted, provided that the above
  53  * copyright notice and this permission notice appear in all copies, and that
  54  * the name of Digital Equipment Corporation not be used in advertising or
  55  * publicity pertaining to distribution of the document or software without
  56  * specific, written prior permission.
  57  *
  58  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  59  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  60  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  61  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  62  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  63  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  64  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  65  * SOFTWARE.
  66  */
  67
  68 /*
  69  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  70  *
  71  * Permission to use, copy, modify, and distribute this software for any
  72  * purpose with or without fee is hereby granted, provided that the above
  73  * copyright notice and this permission notice appear in all copies.
  74  *
  75  * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
  76  * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
  77  * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
  78  * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  79  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  80  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  81  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  82  * SOFTWARE.
  83  */
  84
  85 #include <ctype.h>
  86 #include <netdb.h>
  87 #include <resolv/resolv-internal.h>
  88 #include <res_hconf.h>
  89 #include <stdio.h>
  90 #include <stdio_ext.h>
  91 #include <stdlib.h>
  92 #include <string.h>
  93 #include <unistd.h>
  94 #include <stdint.h>
  95 #include <arpa/inet.h>
  96 #include <arpa/nameser.h>
  97 #include <net/if.h>
  98 #include <netinet/in.h>
  99 #include <sys/param.h>
 100 #include <sys/socket.h>
 101 #include <sys/time.h>
 102 #include <sys/types.h>
 103 #include <inet/net-internal.h>
 104 #include <errno.h>
 105 #include <resolv_conf.h>
 106
 107 static uint32_t net_mask (struct in_addr);
 108
 109 int
 110 res_ninit (res_state statp)
 111 {
 112   return __res_vinit (statp, 0);
 113 }
 114 libc_hidden_def (__res_ninit)
 115
 116 /* Return true if CH separates the netmask in the "sortlist"
 117    directive.  */
 118 static inline bool
 119 is_sort_mask (char ch)
 120 {
 121   return ch == '/' || ch == '&';
 122 }
 123
 124 /* Array of name server addresses.  */
 125 #define DYNARRAY_STRUCT nameserver_list
 126 #define DYNARRAY_ELEMENT const struct sockaddr *
 127 #define DYNARRAY_ELEMENT_FREE(e) free ((struct sockaddr *) *(e))
 128 #define DYNARRAY_INITIAL_SIZE 3
 129 #define DYNARRAY_PREFIX nameserver_list_
 130 #include <malloc/dynarray-skeleton.c>
 131
 132 /* Array of strings for the search array.  The backing store is
 133    managed separately.  */
 134 #define DYNARRAY_STRUCT search_list
 135 #define DYNARRAY_ELEMENT const char *
 136 #define DYNARRAY_INITIAL_SIZE 6
 137 #define DYNARRAY_PREFIX search_list_
 138 #include <malloc/dynarray-skeleton.c>
 139
 140 /* Array of name server addresses.  */
 141 #define DYNARRAY_STRUCT sort_list
 142 #define DYNARRAY_ELEMENT struct resolv_sortlist_entry
 143 #define DYNARRAY_INITIAL_SIZE 0
 144 #define DYNARRAY_PREFIX sort_list_
 145 #include <malloc/dynarray-skeleton.c>
 146
 147 /* resolv.conf parser state and results.  */
 148 struct resolv_conf_parser
 149 {
 150   char *buffer;            /* Temporary buffer for reading lines.  */
 151
 152   struct nameserver_list nameserver_list; /* Nameserver addresses.  */
 153
 154   char *search_list_store; /* Backing storage for search list entries.  */
 155   struct search_list search_list; /* Points into search_list_store.  */
 156
 157   struct sort_list sort_list;   /* Address preference sorting list.  */
 158
 159   /* Configuration template.  The non-array elements are filled in
 160      directly.  The array elements are updated prior to the call to
 161      __resolv_conf_attach.  */
 162   struct resolv_conf template;
 163 };
 164
 165 /* Return true if *PREINIT contains actual preinitialization.  */
 166 static bool
 167 has_preinit_values (const struct __res_state *preinit)
 168 {
 169   return (preinit->retrans != 0 && preinit->retrans != RES_TIMEOUT)
 170     || (preinit->retry != 0 && preinit->retry != RES_DFLRETRY)
 171     || (preinit->options != 0
 172         && (preinit->options & ~RES_INIT) != RES_DEFAULT);
 173 }
 174
 175 static void
 176 resolv_conf_parser_init (struct resolv_conf_parser *parser,
 177                          const struct __res_state *preinit)
 178 {
 179   parser->buffer = NULL;
 180   parser->search_list_store = NULL;
 181   nameserver_list_init (&parser->nameserver_list);
 182   search_list_init (&parser->search_list);
 183   sort_list_init (&parser->sort_list);
 184
 185   if (preinit != NULL)
 186     {
 187       parser->template.retrans = preinit->retrans;
 188       parser->template.retry = preinit->retry;
 189       parser->template.options = preinit->options | RES_INIT;
 190     }
 191   else
 192     {
 193       parser->template.retrans = RES_TIMEOUT;
 194       parser->template.retry = RES_DFLRETRY;
 195       parser->template.options = RES_DEFAULT | RES_INIT;
 196     }
 197   parser->template.ndots = 1;
 198 }
 199
 200 static void
 201 resolv_conf_parser_free (struct resolv_conf_parser *parser)
 202 {
 203   free (parser->buffer);
 204   free (parser->search_list_store);
 205   nameserver_list_free (&parser->nameserver_list);
 206   search_list_free (&parser->search_list);
 207   sort_list_free (&parser->sort_list);
 208 }
 209
 210 /* Allocate a struct sockaddr_in object on the heap, with the
 211    specified address and port.  */
 212 static struct sockaddr *
 213 allocate_address_v4 (struct in_addr a, uint16_t port)
 214 {
 215   struct sockaddr_in *sa4 = malloc (sizeof (*sa4));
 216   if (sa4 == NULL)
 217     return NULL;
 218   sa4->sin_family = AF_INET;
 219   sa4->sin_addr = a;
 220   sa4->sin_port = htons (port);
 221   return (struct sockaddr *) sa4;
 222 }
 223
 224 /* Try to obtain the domain name from the host name and store it in
 225    *RESULT.  Return false on memory allocation failure.  If the domain
 226    name cannot be determined for any other reason, write NULL to
 227    *RESULT and return true.  */
 228 static bool
 229 domain_from_hostname (char **result)
 230 {
 231   char buf[256];
 232   /* gethostbyname may not terminate the buffer.  */
 233   buf[sizeof (buf) - 1] = '\0';
 234   if (__gethostname (buf, sizeof (buf) - 1) == 0)
 235     {
 236       char *dot = strchr (buf, '.');
 237       if (dot != NULL)
 238         {
 239           *result = __strdup (dot + 1);
 240           if (*result == NULL)
 241             return false;
 242           return true;
 243         }
 244     }
 245   *result = NULL;
 246   return true;
 247 }
 248
 249 static void res_setoptions (struct resolv_conf_parser *, const char *options);
 250
 251 /* Internal helper function for __res_vinit, to aid with resource
 252    deallocation and error handling.  Return true on success, false on
 253    failure.  */
 254 static bool
 255 res_vinit_1 (FILE *fp, struct resolv_conf_parser *parser)
 256 {
 257   char *cp;
 258   size_t buffer_size = 0;
 259   bool haveenv = false;
 260
 261   /* Allow user to override the local domain definition.  */
 262   if ((cp = getenv ("LOCALDOMAIN")) != NULL)
 263     {
 264       /* The code below splits the string in place.  */
 265       cp = __strdup (cp);
 266       if (cp == NULL)
 267         return false;
 268       free (parser->search_list_store);
 269       parser->search_list_store = cp;
 270       haveenv = true;
 271
 272       /* The string will be truncated as needed below.  */
 273       search_list_add (&parser->search_list, cp);
 274
 275       /* Set search list to be blank-separated strings from rest of
 276          env value.  Permits users of LOCALDOMAIN to still have a
 277          search list, and anyone to set the one that they want to use
 278          as an individual (even more important now that the rfc1535
 279          stuff restricts searches).  */
 280       for (bool in_name = true; *cp != '\0'; cp++)
 281         {
 282           if (*cp == '\n')
 283             {
 284               *cp = '\0';
 285               break;
 286             }
 287           else if (*cp == ' ' || *cp == '\t')
 288             {
 289               *cp = '\0';
 290               in_name = false;
 291             }
 292           else if (!in_name)
 293             {
 294               search_list_add (&parser->search_list, cp);
 295               in_name = true;
 296             }
 297         }
 298     }
 299
 300 #define MATCH(line, name)                       \
 301   (!strncmp ((line), name, sizeof (name) - 1)     \
 302    && ((line)[sizeof (name) - 1] == ' '           \
 303        || (line)[sizeof (name) - 1] == '\t'))
 304
 305   if (fp != NULL)
 306     {
 307       /* No threads use this stream.  */
 308       __fsetlocking (fp, FSETLOCKING_BYCALLER);
 309       /* Read the config file.  */
 310       while (true)
 311         {
 312           {
 313             ssize_t ret = __getline (&parser->buffer, &buffer_size, fp);
 314             if (ret <= 0)
 315               {
 316                 if (_IO_ferror_unlocked (fp))
 317                   return false;
 318                 else
 319                   break;
 320               }
 321           }
 322
 323           /* Skip comments.  */
 324           if (*parser->buffer == ';' || *parser->buffer == '#')
 325             continue;
 326           /* Read default domain name.  */
 327           if (MATCH (parser->buffer, "domain"))
 328             {
 329               if (haveenv)
 330                 /* LOCALDOMAIN overrides the configuration file.  */
 331                 continue;
 332               cp = parser->buffer + sizeof ("domain") - 1;
 333               while (*cp == ' ' || *cp == '\t')
 334                 cp++;
 335               if ((*cp == '\0') || (*cp == '\n'))
 336                 continue;
 337
 338               cp = __strdup (cp);
 339               if (cp == NULL)
 340                 return false;
 341               free (parser->search_list_store);
 342               parser->search_list_store = cp;
 343               search_list_clear (&parser->search_list);
 344               search_list_add (&parser->search_list, cp);
 345               /* Replace trailing whitespace.  */
 346               if ((cp = strpbrk (cp, " \t\n")) != NULL)
 347                 *cp = '\0';
 348               continue;
 349             }
 350           /* Set search list.  */
 351           if (MATCH (parser->buffer, "search"))
 352             {
 353               if (haveenv)
 354                 /* LOCALDOMAIN overrides the configuration file.  */
 355                 continue;
 356               cp = parser->buffer + sizeof ("search") - 1;
 357               while (*cp == ' ' || *cp == '\t')
 358                 cp++;
 359               if ((*cp == '\0') || (*cp == '\n'))
 360                 continue;
 361
 362               {
 363                 char *p = strchr (cp, '\n');
 364                 if (p != NULL)
 365                   *p = '\0';
 366               }
 367               cp = __strdup (cp);
 368               if (cp == NULL)
 369                 return false;
 370               free (parser->search_list_store);
 371               parser->search_list_store = cp;
 372
 373               /* The string is truncated below.  */
 374               search_list_clear (&parser->search_list);
 375               search_list_add (&parser->search_list, cp);
 376
 377               /* Set search list to be blank-separated strings on rest
 378                  of line.  */
 379               for (bool in_name = true; *cp != '\0'; cp++)
 380                 {
 381                   if (*cp == ' ' || *cp == '\t')
 382                     {
 383                       *cp = '\0';
 384                       in_name = false;
 385                     }
 386                   else if (!in_name)
 387                     {
 388                       search_list_add (&parser->search_list, cp);
 389                       in_name = true;
 390                     }
 391                 }
 392               continue;
 393             }
 394           /* Read nameservers to query.  */
 395           if (MATCH (parser->buffer, "nameserver"))
 396             {
 397               struct in_addr a;
 398
 399               cp = parser->buffer + sizeof ("nameserver") - 1;
 400               while (*cp == ' ' || *cp == '\t')
 401                 cp++;
 402               struct sockaddr *sa;
 403               if ((*cp != '\0') && (*cp != '\n') && __inet_aton (cp, &a))
 404                 {
 405                   sa = allocate_address_v4 (a, NAMESERVER_PORT);
 406                   if (sa == NULL)
 407                     return false;
 408                 }
 409               else
 410                 {
 411                   struct in6_addr a6;
 412                   char *el;
 413
 414                   if ((el = strpbrk (cp, " \t\n")) != NULL)
 415                     *el = '\0';
 416                   if ((el = strchr (cp, SCOPE_DELIMITER)) != NULL)
 417                     *el = '\0';
 418                   if ((*cp != '\0') && (__inet_pton (AF_INET6, cp, &a6) > 0))
 419                     {
 420                       struct sockaddr_in6 *sa6;
 421
 422                       sa6 = malloc (sizeof (*sa6));
 423                       if (sa6 == NULL)
 424                         return false;
 425
 426                       sa6->sin6_family = AF_INET6;
 427                       sa6->sin6_port = htons (NAMESERVER_PORT);
 428                       sa6->sin6_flowinfo = 0;
 429                       sa6->sin6_addr = a6;
 430
 431                       sa6->sin6_scope_id = 0;
 432                       if (__glibc_likely (el != NULL))
 433                         /* Ignore errors, for backwards
 434                            compatibility.  */
 435                         __inet6_scopeid_pton
 436                           (&a6, el + 1, &sa6->sin6_scope_id);
 437                       sa = (struct sockaddr *) sa6;
 438                     }
 439                   else
 440                     /* IPv6 address parse failure.  */
 441                     sa = NULL;
 442                 }
 443               if (sa != NULL)
 444                 {
 445                   const struct sockaddr **p = nameserver_list_emplace
 446                     (&parser->nameserver_list);
 447                   if (p != NULL)
 448                     *p = sa;
 449                   else
 450                     {
 451                       free (sa);
 452                       return false;
 453                     }
 454                 }
 455               continue;
 456             }
 457           if (MATCH (parser->buffer, "sortlist"))
 458             {
 459               struct in_addr a;
 460
 461               cp = parser->buffer + sizeof ("sortlist") - 1;
 462               while (true)
 463                 {
 464                   while (*cp == ' ' || *cp == '\t')
 465                     cp++;
 466                   if (*cp == '\0' || *cp == '\n' || *cp == ';')
 467                     break;
 468                   char *net = cp;
 469                   while (*cp && !is_sort_mask (*cp) && *cp != ';'
 470                          && isascii (*cp) && !isspace (*cp))
 471                     cp++;
 472                   char separator = *cp;
 473                   *cp = 0;
 474                   struct resolv_sortlist_entry e;
 475                   if (__inet_aton (net, &a))
 476                     {
 477                       e.addr = a;
 478                       if (is_sort_mask (separator))
 479                         {
 480                           *cp++ = separator;
 481                           net = cp;
 482                           while (*cp && *cp != ';'
 483                                  && isascii (*cp) && !isspace (*cp))
 484                             cp++;
 485                           separator = *cp;
 486                           *cp = 0;
 487                           if (__inet_aton (net, &a))
 488                             e.mask = a.s_addr;
 489                           else
 490                             e.mask = net_mask (e.addr);
 491                         }
 492                       else
 493                         e.mask = net_mask (e.addr);
 494                       sort_list_add (&parser->sort_list, e);
 495                     }
 496                   *cp = separator;
 497                 }
 498               continue;
 499             }
 500           if (MATCH (parser->buffer, "options"))
 501             {
 502               res_setoptions (parser, parser->buffer + sizeof ("options") - 1);
 503               continue;
 504             }
 505         }
 506       fclose (fp);
 507     }
 508   if (__glibc_unlikely (nameserver_list_size (&parser->nameserver_list) == 0))
 509     {
 510       const struct sockaddr **p
 511         = nameserver_list_emplace (&parser->nameserver_list);
 512       if (p == NULL)
 513         return false;
 514       *p = allocate_address_v4 (__inet_makeaddr (IN_LOOPBACKNET, 1),
 515                                 NAMESERVER_PORT);
 516       if (*p == NULL)
 517         return false;
 518     }
 519
 520   if (search_list_size (&parser->search_list) == 0)
 521     {
 522       char *domain;
 523       if (!domain_from_hostname (&domain))
 524         return false;
 525       if (domain != NULL)
 526         {
 527           free (parser->search_list_store);
 528           parser->search_list_store = domain;
 529           search_list_add (&parser->search_list, domain);
 530         }
 531     }
 532
 533   if ((cp = getenv ("RES_OPTIONS")) != NULL)
 534     res_setoptions (parser, cp);
 535
 536   if (nameserver_list_has_failed (&parser->nameserver_list)
 537       || search_list_has_failed (&parser->search_list)
 538       || sort_list_has_failed (&parser->sort_list))
 539     {
 540       __set_errno (ENOMEM);
 541       return false;
 542     }
 543
 544   return true;
 545 }
 546
 547 struct resolv_conf *
 548 __resolv_conf_load (struct __res_state *preinit)
 549 {
 550   /* Ensure that /etc/hosts.conf has been loaded (once).  */
 551   _res_hconf_init ();
 552
 553   FILE *fp = fopen (_PATH_RESCONF, "rce");
 554   if (fp == NULL)
 555     switch (errno)
 556       {
 557       case EACCES:
 558       case EISDIR:
 559       case ELOOP:
 560       case ENOENT:
 561       case ENOTDIR:
 562       case EPERM:
 563         /* Ignore these errors.  They are persistent errors caused
 564            by file system contents.  */
 565         break;
 566       default:
 567         /* Other errors refer to resource allocation problems and
 568            need to be handled by the application.  */
 569         return NULL;
 570       }
 571
 572   struct resolv_conf_parser parser;
 573   resolv_conf_parser_init (&parser, preinit);
 574
 575   struct resolv_conf *conf = NULL;
 576   if (res_vinit_1 (fp, &parser))
 577     {
 578       parser.template.nameserver_list
 579         = nameserver_list_begin (&parser.nameserver_list);
 580       parser.template.nameserver_list_size
 581         = nameserver_list_size (&parser.nameserver_list);
 582       parser.template.search_list = search_list_begin (&parser.search_list);
 583       parser.template.search_list_size
 584         = search_list_size (&parser.search_list);
 585       parser.template.sort_list = sort_list_begin (&parser.sort_list);
 586       parser.template.sort_list_size = sort_list_size (&parser.sort_list);
 587       conf = __resolv_conf_allocate (&parser.template);
 588     }
 589   resolv_conf_parser_free (&parser);
 590
 591   return conf;
 592 }
 593
 594 /* Set up default settings.  If the /etc/resolv.conf configuration
 595    file exist, the values there will have precedence.  Otherwise, the
 596    server address is set to INADDR_LOOPBACK and the default domain
 597    name comes from gethostname.  The RES_OPTIONS and LOCALDOMAIN
 598    environment variables can be used to override some settings.
 599    Return 0 if completes successfully, -1 on error.  */
 600 int
 601 __res_vinit (res_state statp, int preinit)
 602 {
 603   struct resolv_conf *conf;
 604   if (preinit && has_preinit_values (statp))
 605     /* For the preinit case, we cannot use the cached configuration
 606        because some settings could be different.  */
 607     conf = __resolv_conf_load (statp);
 608   else
 609     conf = __resolv_conf_get_current ();
 610   if (conf == NULL)
 611     return -1;
 612
 613   bool ok = __resolv_conf_attach (statp, conf);
 614   __resolv_conf_put (conf);
 615   if (ok)
 616     {
 617       if (preinit)
 618         statp->id = res_randomid ();
 619       return 0;
 620     }
 621   else
 622     return -1;
 623 }
 624
 625 static void
 626 res_setoptions (struct resolv_conf_parser *parser, const char *options)
 627 {
 628   const char *cp = options;
 629
 630   while (*cp)
 631     {
 632       /* Skip leading and inner runs of spaces.  */
 633       while (*cp == ' ' || *cp == '\t')
 634         cp++;
 635       /* Search for and process individual options.  */
 636       if (!strncmp (cp, "ndots:", sizeof ("ndots:") - 1))
 637         {
 638           int i = atoi (cp + sizeof ("ndots:") - 1);
 639           if (i <= RES_MAXNDOTS)
 640             parser->template.ndots = i;
 641           else
 642             parser->template.ndots = RES_MAXNDOTS;
 643         }
 644       else if (!strncmp (cp, "timeout:", sizeof ("timeout:") - 1))
 645         {
 646           int i = atoi (cp + sizeof ("timeout:") - 1);
 647           if (i <= RES_MAXRETRANS)
 648             parser->template.retrans = i;
 649           else
 650             parser->template.retrans = RES_MAXRETRANS;
 651         }
 652       else if (!strncmp (cp, "attempts:", sizeof ("attempts:") - 1))
 653         {
 654           int i = atoi (cp + sizeof ("attempts:") - 1);
 655           if (i <= RES_MAXRETRY)
 656             parser->template.retry = i;
 657           else
 658             parser->template.retry = RES_MAXRETRY;
 659         }
 660       else
 661         {
 662           static const struct
 663           {
 664             char str[22];
 665             uint8_t len;
 666             uint8_t clear;
 667             unsigned long int flag;
 668           } options[] = {
 669 #define STRnLEN(str) str, sizeof (str) - 1
 670             { STRnLEN ("inet6"), 0, DEPRECATED_RES_USE_INET6 },
 671             { STRnLEN ("rotate"), 0, RES_ROTATE },
 672             { STRnLEN ("edns0"), 0, RES_USE_EDNS0 },
 673             { STRnLEN ("single-request-reopen"), 0, RES_SNGLKUPREOP },
 674             { STRnLEN ("single-request"), 0, RES_SNGLKUP },
 675             { STRnLEN ("no_tld_query"), 0, RES_NOTLDQUERY },
 676             { STRnLEN ("no-tld-query"), 0, RES_NOTLDQUERY },
 677             { STRnLEN ("no-reload"), 0, RES_NORELOAD },
 678             { STRnLEN ("use-vc"), 0, RES_USEVC }
 679           };
 680 #define noptions (sizeof (options) / sizeof (options[0]))
 681           for (int i = 0; i < noptions; ++i)
 682             if (strncmp (cp, options[i].str, options[i].len) == 0)
 683               {
 684                 if (options[i].clear)
 685                   parser->template.options &= options[i].flag;
 686                 else
 687                   parser->template.options |= options[i].flag;
 688                 break;
 689               }
 690         }
 691       /* Skip to next run of spaces.  */
 692       while (*cp && *cp != ' ' && *cp != '\t')
 693         cp++;
 694     }
 695 }
 696
 697 static uint32_t
 698 net_mask (struct in_addr in)
 699 {
 700   uint32_t i = ntohl (in.s_addr);
 701
 702   if (IN_CLASSA (i))
 703     return htonl (IN_CLASSA_NET);
 704   else if (IN_CLASSB (i))
 705     return htonl (IN_CLASSB_NET);
 706   return htonl (IN_CLASSC_NET);
 707 }