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