resolv/res_query.c

   1 /*
   2  * Copyright (c) 1988, 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_query.c   8.1 (Berkeley) 6/4/93";
  69 static const char rcsid[] = "$BINDId: res_query.c,v 8.20 2000/02/29 05:39:12 vixie Exp $";
  70 #endif /* LIBC_SCCS and not lint */
  71
  72 #include <assert.h>
  73 #include <sys/types.h>
  74 #include <sys/param.h>
  75 #include <netinet/in.h>
  76 #include <arpa/inet.h>
  77 #include <arpa/nameser.h>
  78 #include <ctype.h>
  79 #include <errno.h>
  80 #include <netdb.h>
  81 #include <resolv.h>
  82 #include <stdio.h>
  83 #include <stdlib.h>
  84 #include <string.h>
  85
  86 /* Options.  Leave them on. */
  87 /* #undef DEBUG */
  88
  89 #if PACKETSZ > 65536
  90 #define MAXPACKET       PACKETSZ
  91 #else
  92 #define MAXPACKET       65536
  93 #endif
  94
  95 #define QUERYSIZE       (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)
  96
  97 static int
  98 __libc_res_nquerydomain(res_state statp, const char *name, const char *domain,
  99                         int class, int type, u_char *answer, int anslen,
 100                         u_char **answerp, u_char **answerp2, int *nanswerp2,
 101                         int *resplen2);
 102
 103 /*
 104  * Formulate a normal query, send, and await answer.
 105  * Returned answer is placed in supplied buffer "answer".
 106  * Perform preliminary check of answer, returning success only
 107  * if no error is indicated and the answer count is nonzero.
 108  * Return the size of the response on success, -1 on error.
 109  * Error number is left in H_ERRNO.
 110  *
 111  * Caller must parse answer and determine whether it answers the question.
 112  */
 113 int
 114 __libc_res_nquery(res_state statp,
 115                   const char *name,     /* domain name */
 116                   int class, int type,  /* class and type of query */
 117                   u_char *answer,       /* buffer to put answer */
 118                   int anslen,           /* size of answer buffer */
 119                   u_char **answerp,     /* if buffer needs to be enlarged */
 120                   u_char **answerp2,
 121                   int *nanswerp2,
 122                   int *resplen2)
 123 {
 124         HEADER *hp = (HEADER *) answer;
 125         int n, use_malloc = 0;
 126         u_int oflags = statp->_flags;
 127
 128         size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE;
 129         u_char *buf = alloca (bufsize);
 130         u_char *query1 = buf;
 131         int nquery1 = -1;
 132         u_char *query2 = NULL;
 133         int nquery2 = 0;
 134
 135  again:
 136         hp->rcode = NOERROR;    /* default */
 137
 138 #ifdef DEBUG
 139         if (statp->options & RES_DEBUG)
 140                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 141 #endif
 142
 143         if (type == T_UNSPEC)
 144           {
 145             n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL,
 146                              query1, bufsize);
 147             if (n > 0)
 148               {
 149                 if ((oflags & RES_F_EDNS0ERR) == 0
 150                     && (statp->options & RES_USE_EDNS0) != 0)
 151                   {
 152                     n = __res_nopt(statp, n, query1, bufsize, anslen / 2);
 153                     if (n < 0)
 154                       goto unspec_nomem;
 155                   }
 156
 157                 nquery1 = n;
 158                 /* Align the buffer.  */
 159                 int npad = ((nquery1 + __alignof__ (HEADER) - 1)
 160                             & ~(__alignof__ (HEADER) - 1)) - nquery1;
 161                 if (n > bufsize - npad)
 162                   {
 163                     n = -1;
 164                     goto unspec_nomem;
 165                   }
 166                 int nused = n + npad;
 167                 query2 = buf + nused;
 168                 n = res_nmkquery(statp, QUERY, name, class, T_AAAA, NULL, 0,
 169                                  NULL, query2, bufsize - nused);
 170                 if (n > 0
 171                     && (oflags & RES_F_EDNS0ERR) == 0
 172                     && (statp->options & RES_USE_EDNS0) != 0)
 173                   n = __res_nopt(statp, n, query2, bufsize - nused - n,
 174                                  anslen / 2);
 175                 nquery2 = n;
 176               }
 177
 178           unspec_nomem:;
 179           }
 180         else
 181           {
 182             n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 183                              query1, bufsize);
 184
 185             if (n > 0
 186                 && (oflags & RES_F_EDNS0ERR) == 0
 187                 && (statp->options & RES_USE_EDNS0) != 0)
 188               n = __res_nopt(statp, n, query1, bufsize, anslen);
 189
 190             nquery1 = n;
 191           }
 192
 193         if (__builtin_expect (n <= 0, 0) && !use_malloc) {
 194                 /* Retry just in case res_nmkquery failed because of too
 195                    short buffer.  Shouldn't happen.  */
 196                 bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET;
 197                 buf = malloc (bufsize);
 198                 if (buf != NULL) {
 199                         query1 = buf;
 200                         use_malloc = 1;
 201                         goto again;
 202                 }
 203         }
 204         if (__builtin_expect (n <= 0, 0)) {
 205                 /* If the query choked with EDNS0, retry without EDNS0.  */
 206                 if ((statp->options & RES_USE_EDNS0) != 0
 207                     && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 208                         statp->_flags |= RES_F_EDNS0ERR;
 209 #ifdef DEBUG
 210                         if (statp->options & RES_DEBUG)
 211                                 printf(";; res_nquery: retry without EDNS0\n");
 212 #endif
 213                         goto again;
 214                 }
 215 #ifdef DEBUG
 216                 if (statp->options & RES_DEBUG)
 217                         printf(";; res_query: mkquery failed\n");
 218 #endif
 219                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 220                 if (use_malloc)
 221                         free (buf);
 222                 return (n);
 223         }
 224         assert (answerp == NULL || (void *) *answerp == (void *) answer);
 225         n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer,
 226                              anslen, answerp, answerp2, nanswerp2, resplen2);
 227         if (use_malloc)
 228                 free (buf);
 229         if (n < 0) {
 230 #ifdef DEBUG
 231                 if (statp->options & RES_DEBUG)
 232                         printf(";; res_query: send error\n");
 233 #endif
 234                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 235                 return (n);
 236         }
 237
 238         if (answerp != NULL)
 239           /* __libc_res_nsend might have reallocated the buffer.  */
 240           hp = (HEADER *) *answerp;
 241
 242         /* We simplify the following tests by assigning HP to HP2.  It
 243            is easy to verify that this is the same as ignoring all
 244            tests of HP2.  */
 245         HEADER *hp2 = answerp2 ? (HEADER *) *answerp2 : hp;
 246
 247         if (n < (int) sizeof (HEADER) && answerp2 != NULL
 248             && *resplen2 > (int) sizeof (HEADER))
 249           {
 250             /* Special case of partial answer.  */
 251             assert (hp != hp2);
 252             hp = hp2;
 253           }
 254         else if (answerp2 != NULL && *resplen2 < (int) sizeof (HEADER)
 255                  && n > (int) sizeof (HEADER))
 256           {
 257             /* Special case of partial answer.  */
 258             assert (hp != hp2);
 259             hp2 = hp;
 260           }
 261
 262         if ((hp->rcode != NOERROR || ntohs(hp->ancount) == 0)
 263             && (hp2->rcode != NOERROR || ntohs(hp2->ancount) == 0)) {
 264 #ifdef DEBUG
 265                 if (statp->options & RES_DEBUG) {
 266                         printf(";; rcode = %d, ancount=%d\n", hp->rcode,
 267                             ntohs(hp->ancount));
 268                         if (hp != hp2)
 269                           printf(";; rcode2 = %d, ancount2=%d\n", hp2->rcode,
 270                                  ntohs(hp2->ancount));
 271                 }
 272 #endif
 273                 switch (hp->rcode == NOERROR ? hp2->rcode : hp->rcode) {
 274                 case NXDOMAIN:
 275                         if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
 276                             || (hp2->rcode == NOERROR
 277                                 && ntohs (hp2->ancount) != 0))
 278                                 goto success;
 279                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 280                         break;
 281                 case SERVFAIL:
 282                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 283                         break;
 284                 case NOERROR:
 285                         if (ntohs (hp->ancount) != 0
 286                             || ntohs (hp2->ancount) != 0)
 287                                 goto success;
 288                         RES_SET_H_ERRNO(statp, NO_DATA);
 289                         break;
 290                 case FORMERR:
 291                 case NOTIMP:
 292                 case REFUSED:
 293                 default:
 294                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 295                         break;
 296                 }
 297                 return (-1);
 298         }
 299  success:
 300         return (n);
 301 }
 302 libresolv_hidden_def (__libc_res_nquery)
 303
 304 int
 305 res_nquery(res_state statp,
 306            const char *name,    /* domain name */
 307            int class, int type, /* class and type of query */
 308            u_char *answer,      /* buffer to put answer */
 309            int anslen)          /* size of answer buffer */
 310 {
 311         return __libc_res_nquery(statp, name, class, type, answer, anslen,
 312                                  NULL, NULL, NULL, NULL);
 313 }
 314 libresolv_hidden_def (res_nquery)
 315
 316 /*
 317  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 318  * Return the size of the response on success, -1 on error.
 319  * If enabled, implement search rules until answer or unrecoverable failure
 320  * is detected.  Error code, if any, is left in H_ERRNO.
 321  */
 322 int
 323 __libc_res_nsearch(res_state statp,
 324                    const char *name,    /* domain name */
 325                    int class, int type, /* class and type of query */
 326                    u_char *answer,      /* buffer to put answer */
 327                    int anslen,          /* size of answer */
 328                    u_char **answerp,
 329                    u_char **answerp2,
 330                    int *nanswerp2,
 331                    int *resplen2)
 332 {
 333         const char *cp, * const *domain;
 334         HEADER *hp = (HEADER *) answer;
 335         char tmp[NS_MAXDNAME];
 336         u_int dots;
 337         int trailing_dot, ret, saved_herrno;
 338         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 339         int tried_as_is = 0;
 340
 341         __set_errno (0);
 342         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */
 343
 344         dots = 0;
 345         for (cp = name; *cp != '\0'; cp++)
 346                 dots += (*cp == '.');
 347         trailing_dot = 0;
 348         if (cp > name && *--cp == '.')
 349                 trailing_dot++;
 350
 351         /* If there aren't any dots, it could be a user-level alias. */
 352         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 353                 return (__libc_res_nquery(statp, cp, class, type, answer,
 354                                           anslen, answerp, answerp2,
 355                                           nanswerp2, resplen2));
 356
 357 #ifdef DEBUG
 358         if (statp->options & RES_DEBUG)
 359                 printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
 360                        (int)dots,(int)statp->ndots,(int)trailing_dot,name);
 361 #endif
 362
 363         /*
 364          * If there are enough dots in the name, let's just give it a
 365          * try 'as is'. The threshold can be set with the "ndots" option.
 366          * Also, query 'as is', if there is a trailing dot in the name.
 367          */
 368         saved_herrno = -1;
 369         if (dots >= statp->ndots || trailing_dot) {
 370                 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
 371                                               answer, anslen, answerp,
 372                                               answerp2, nanswerp2, resplen2);
 373                 if (ret > 0 || trailing_dot)
 374                         return (ret);
 375                 saved_herrno = h_errno;
 376                 tried_as_is++;
 377                 if (answerp && *answerp != answer) {
 378                         answer = *answerp;
 379                         anslen = MAXPACKET;
 380                 }
 381                 if (answerp2
 382                     && (*answerp2 < answer || *answerp2 >= answer + anslen))
 383                   {
 384                     free (*answerp2);
 385                     *answerp2 = NULL;
 386                   }
 387         }
 388
 389         /*
 390          * We do at least one level of search if
 391          *      - there is no dot and RES_DEFNAME is set, or
 392          *      - there is at least one dot, there is no trailing dot,
 393          *        and RES_DNSRCH is set.
 394          */
 395         if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
 396             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
 397                 int done = 0;
 398
 399                 for (domain = (const char * const *)statp->dnsrch;
 400                      *domain && !done;
 401                      domain++) {
 402
 403                         if (domain[0][0] == '\0' ||
 404                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 405                                 root_on_list++;
 406
 407                         ret = __libc_res_nquerydomain(statp, name, *domain,
 408                                                       class, type,
 409                                                       answer, anslen, answerp,
 410                                                       answerp2, nanswerp2,
 411                                                       resplen2);
 412                         if (ret > 0)
 413                                 return (ret);
 414
 415                         if (answerp && *answerp != answer) {
 416                                 answer = *answerp;
 417                                 anslen = MAXPACKET;
 418                         }
 419                         if (answerp2
 420                             && (*answerp2 < answer
 421                                 || *answerp2 >= answer + anslen))
 422                           {
 423                             free (*answerp2);
 424                             *answerp2 = NULL;
 425                           }
 426
 427                         /*
 428                          * If no server present, give up.
 429                          * If name isn't found in this domain,
 430                          * keep trying higher domains in the search list
 431                          * (if that's enabled).
 432                          * On a NO_DATA error, keep trying, otherwise
 433                          * a wildcard entry of another type could keep us
 434                          * from finding this entry higher in the domain.
 435                          * If we get some other error (negative answer or
 436                          * server failure), then stop searching up,
 437                          * but try the input name below in case it's
 438                          * fully-qualified.
 439                          */
 440                         if (errno == ECONNREFUSED) {
 441                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 442                                 return (-1);
 443                         }
 444
 445                         switch (statp->res_h_errno) {
 446                         case NO_DATA:
 447                                 got_nodata++;
 448                                 /* FALLTHROUGH */
 449                         case HOST_NOT_FOUND:
 450                                 /* keep trying */
 451                                 break;
 452                         case TRY_AGAIN:
 453                                 if (hp->rcode == SERVFAIL) {
 454                                         /* try next search element, if any */
 455                                         got_servfail++;
 456                                         break;
 457                                 }
 458                                 /* FALLTHROUGH */
 459                         default:
 460                                 /* anything else implies that we're done */
 461                                 done++;
 462                         }
 463
 464                         /* if we got here for some reason other than DNSRCH,
 465                          * we only wanted one iteration of the loop, so stop.
 466                          */
 467                         if ((statp->options & RES_DNSRCH) == 0)
 468                                 done++;
 469                 }
 470         }
 471
 472         /*
 473          * If the name has any dots at all, and no earlier 'as-is' query
 474          * for the name, and "." is not on the search list, then try an as-is
 475          * query now.
 476          */
 477         if (dots && !(tried_as_is || root_on_list)) {
 478                 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
 479                                               answer, anslen, answerp,
 480                                               answerp2, nanswerp2, resplen2);
 481                 if (ret > 0)
 482                         return (ret);
 483         }
 484
 485         /* if we got here, we didn't satisfy the search.
 486          * if we did an initial full query, return that query's H_ERRNO
 487          * (note that we wouldn't be here if that query had succeeded).
 488          * else if we ever got a nodata, send that back as the reason.
 489          * else send back meaningless H_ERRNO, that being the one from
 490          * the last DNSRCH we did.
 491          */
 492         if (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen))
 493           {
 494             free (*answerp2);
 495             *answerp2 = NULL;
 496           }
 497         if (saved_herrno != -1)
 498                 RES_SET_H_ERRNO(statp, saved_herrno);
 499         else if (got_nodata)
 500                 RES_SET_H_ERRNO(statp, NO_DATA);
 501         else if (got_servfail)
 502                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 503         return (-1);
 504 }
 505 libresolv_hidden_def (__libc_res_nsearch)
 506
 507 int
 508 res_nsearch(res_state statp,
 509             const char *name,   /* domain name */
 510             int class, int type,        /* class and type of query */
 511             u_char *answer,     /* buffer to put answer */
 512             int anslen)         /* size of answer */
 513 {
 514         return __libc_res_nsearch(statp, name, class, type, answer,
 515                                   anslen, NULL, NULL, NULL, NULL);
 516 }
 517 libresolv_hidden_def (res_nsearch)
 518
 519 /*
 520  * Perform a call on res_query on the concatenation of name and domain,
 521  * removing a trailing dot from name if domain is NULL.
 522  */
 523 static int
 524 __libc_res_nquerydomain(res_state statp,
 525                         const char *name,
 526                         const char *domain,
 527                         int class, int type,    /* class and type of query */
 528                         u_char *answer,         /* buffer to put answer */
 529                         int anslen,                     /* size of answer */
 530                         u_char **answerp,
 531                         u_char **answerp2,
 532                         int *nanswerp2,
 533                         int *resplen2)
 534 {
 535         char nbuf[MAXDNAME];
 536         const char *longname = nbuf;
 537         int n, d;
 538
 539 #ifdef DEBUG
 540         if (statp->options & RES_DEBUG)
 541                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 542                        name, domain?domain:"<Nil>", class, type);
 543 #endif
 544         if (domain == NULL) {
 545                 /*
 546                  * Check for trailing '.';
 547                  * copy without '.' if present.
 548                  */
 549                 n = strlen(name);
 550                 if (n >= MAXDNAME) {
 551                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 552                         return (-1);
 553                 }
 554                 n--;
 555                 if (n >= 0 && name[n] == '.') {
 556                         strncpy(nbuf, name, n);
 557                         nbuf[n] = '\0';
 558                 } else
 559                         longname = name;
 560         } else {
 561                 n = strlen(name);
 562                 d = strlen(domain);
 563                 if (n + d + 1 >= MAXDNAME) {
 564                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 565                         return (-1);
 566                 }
 567                 sprintf(nbuf, "%s.%s", name, domain);
 568         }
 569         return (__libc_res_nquery(statp, longname, class, type, answer,
 570                                   anslen, answerp, answerp2, nanswerp2,
 571                                   resplen2));
 572 }
 573
 574 int
 575 res_nquerydomain(res_state statp,
 576             const char *name,
 577             const char *domain,
 578             int class, int type,        /* class and type of query */
 579             u_char *answer,             /* buffer to put answer */
 580             int anslen)         /* size of answer */
 581 {
 582         return __libc_res_nquerydomain(statp, name, domain, class, type,
 583                                        answer, anslen, NULL, NULL, NULL, NULL);
 584 }
 585 libresolv_hidden_def (res_nquerydomain)
 586
 587 const char *
 588 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 589         char *file, *cp1, *cp2;
 590         char buf[BUFSIZ];
 591         FILE *fp;
 592
 593         if (statp->options & RES_NOALIASES)
 594                 return (NULL);
 595         file = getenv("HOSTALIASES");
 596         if (file == NULL || (fp = fopen(file, "r")) == NULL)
 597                 return (NULL);
 598         setbuf(fp, NULL);
 599         buf[sizeof(buf) - 1] = '\0';
 600         while (fgets(buf, sizeof(buf), fp)) {
 601                 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
 602                         ;
 603                 if (!*cp1)
 604                         break;
 605                 *cp1 = '\0';
 606                 if (ns_samename(buf, name) == 1) {
 607                         while (isspace(*++cp1))
 608                                 ;
 609                         if (!*cp1)
 610                                 break;
 611                         for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
 612                                 ;
 613                         *cp2 = '\0';
 614                         strncpy(dst, cp1, siz - 1);
 615                         dst[siz - 1] = '\0';
 616                         fclose(fp);
 617                         return (dst);
 618                 }
 619         }
 620         fclose(fp);
 621         return (NULL);
 622 }
 623 libresolv_hidden_def (res_hostalias)