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, int *answerp2_malloced);
 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                   int *answerp2_malloced)
 124 {
 125         HEADER *hp = (HEADER *) answer;
 126         HEADER *hp2;
 127         int n, use_malloc = 0;
 128         u_int oflags = statp->_flags;
 129
 130         size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE;
 131         u_char *buf = alloca (bufsize);
 132         u_char *query1 = buf;
 133         int nquery1 = -1;
 134         u_char *query2 = NULL;
 135         int nquery2 = 0;
 136
 137  again:
 138         hp->rcode = NOERROR;    /* default */
 139
 140 #ifdef DEBUG
 141         if (statp->options & RES_DEBUG)
 142                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 143 #endif
 144
 145         if (type == T_UNSPEC)
 146           {
 147             n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL,
 148                              query1, bufsize);
 149             if (n > 0)
 150               {
 151                 if ((oflags & RES_F_EDNS0ERR) == 0
 152                     && (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
 153                   {
 154                     n = __res_nopt(statp, n, query1, bufsize, anslen / 2);
 155                     if (n < 0)
 156                       goto unspec_nomem;
 157                   }
 158
 159                 nquery1 = n;
 160                 /* Align the buffer.  */
 161                 int npad = ((nquery1 + __alignof__ (HEADER) - 1)
 162                             & ~(__alignof__ (HEADER) - 1)) - nquery1;
 163                 if (n > bufsize - npad)
 164                   {
 165                     n = -1;
 166                     goto unspec_nomem;
 167                   }
 168                 int nused = n + npad;
 169                 query2 = buf + nused;
 170                 n = res_nmkquery(statp, QUERY, name, class, T_AAAA, NULL, 0,
 171                                  NULL, query2, bufsize - nused);
 172                 if (n > 0
 173                     && (oflags & RES_F_EDNS0ERR) == 0
 174                     && (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
 175                   n = __res_nopt(statp, n, query2, bufsize - nused - n,
 176                                  anslen / 2);
 177                 nquery2 = n;
 178               }
 179
 180           unspec_nomem:;
 181           }
 182         else
 183           {
 184             n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 185                              query1, bufsize);
 186
 187             if (n > 0
 188                 && (oflags & RES_F_EDNS0ERR) == 0
 189                 && (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
 190               n = __res_nopt(statp, n, query1, bufsize, anslen);
 191
 192             nquery1 = n;
 193           }
 194
 195         if (__builtin_expect (n <= 0, 0) && !use_malloc) {
 196                 /* Retry just in case res_nmkquery failed because of too
 197                    short buffer.  Shouldn't happen.  */
 198                 bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET;
 199                 buf = malloc (bufsize);
 200                 if (buf != NULL) {
 201                         query1 = buf;
 202                         use_malloc = 1;
 203                         goto again;
 204                 }
 205         }
 206         if (__glibc_unlikely (n <= 0))       {
 207                 /* If the query choked with EDNS0, retry without EDNS0.  */
 208                 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0
 209                     && ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 210                         statp->_flags |= RES_F_EDNS0ERR;
 211 #ifdef DEBUG
 212                         if (statp->options & RES_DEBUG)
 213                                 printf(";; res_nquery: retry without EDNS0\n");
 214 #endif
 215                         goto again;
 216                 }
 217 #ifdef DEBUG
 218                 if (statp->options & RES_DEBUG)
 219                         printf(";; res_query: mkquery failed\n");
 220 #endif
 221                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 222                 if (use_malloc)
 223                         free (buf);
 224                 return (n);
 225         }
 226         assert (answerp == NULL || (void *) *answerp == (void *) answer);
 227         n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer,
 228                              anslen, answerp, answerp2, nanswerp2, resplen2,
 229                              answerp2_malloced);
 230         if (use_malloc)
 231                 free (buf);
 232         if (n < 0) {
 233 #ifdef DEBUG
 234                 if (statp->options & RES_DEBUG)
 235                         printf(";; res_query: send error\n");
 236 #endif
 237                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 238                 return (n);
 239         }
 240
 241         if (answerp != NULL)
 242           /* __libc_res_nsend might have reallocated the buffer.  */
 243           hp = (HEADER *) *answerp;
 244
 245         /* We simplify the following tests by assigning HP to HP2 or
 246            vice versa.  It is easy to verify that this is the same as
 247            ignoring all tests of HP or HP2.  */
 248         if (answerp2 == NULL || *resplen2 < (int) sizeof (HEADER))
 249           {
 250             hp2 = hp;
 251           }
 252         else
 253           {
 254             hp2 = (HEADER *) *answerp2;
 255             if (n < (int) sizeof (HEADER))
 256               {
 257                 hp = hp2;
 258               }
 259           }
 260
 261         /* Make sure both hp and hp2 are defined */
 262         assert((hp != NULL) && (hp2 != NULL));
 263
 264         if ((hp->rcode != NOERROR || ntohs(hp->ancount) == 0)
 265             && (hp2->rcode != NOERROR || ntohs(hp2->ancount) == 0)) {
 266 #ifdef DEBUG
 267                 if (statp->options & RES_DEBUG) {
 268                         printf(";; rcode = %d, ancount=%d\n", hp->rcode,
 269                             ntohs(hp->ancount));
 270                         if (hp != hp2)
 271                           printf(";; rcode2 = %d, ancount2=%d\n", hp2->rcode,
 272                                  ntohs(hp2->ancount));
 273                 }
 274 #endif
 275                 switch (hp->rcode == NOERROR ? hp2->rcode : hp->rcode) {
 276                 case NXDOMAIN:
 277                         if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
 278                             || (hp2->rcode == NOERROR
 279                                 && ntohs (hp2->ancount) != 0))
 280                                 goto success;
 281                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 282                         break;
 283                 case SERVFAIL:
 284                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 285                         break;
 286                 case NOERROR:
 287                         if (ntohs (hp->ancount) != 0
 288                             || ntohs (hp2->ancount) != 0)
 289                                 goto success;
 290                         RES_SET_H_ERRNO(statp, NO_DATA);
 291                         break;
 292                 case FORMERR:
 293                 case NOTIMP:
 294                         /* Servers must not reply to AAAA queries with
 295                            NOTIMP etc but some of them do.  */
 296                         if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
 297                             || (hp2->rcode == NOERROR
 298                                 && ntohs (hp2->ancount) != 0))
 299                                 goto success;
 300                         /* FALLTHROUGH */
 301                 case REFUSED:
 302                 default:
 303                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 304                         break;
 305                 }
 306                 return (-1);
 307         }
 308  success:
 309         return (n);
 310 }
 311 libresolv_hidden_def (__libc_res_nquery)
 312
 313 int
 314 res_nquery(res_state statp,
 315            const char *name,    /* domain name */
 316            int class, int type, /* class and type of query */
 317            u_char *answer,      /* buffer to put answer */
 318            int anslen)          /* size of answer buffer */
 319 {
 320         return __libc_res_nquery(statp, name, class, type, answer, anslen,
 321                                  NULL, NULL, NULL, NULL, NULL);
 322 }
 323 libresolv_hidden_def (res_nquery)
 324
 325 /*
 326  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 327  * Return the size of the response on success, -1 on error.
 328  * If enabled, implement search rules until answer or unrecoverable failure
 329  * is detected.  Error code, if any, is left in H_ERRNO.
 330  */
 331 int
 332 __libc_res_nsearch(res_state statp,
 333                    const char *name,    /* domain name */
 334                    int class, int type, /* class and type of query */
 335                    u_char *answer,      /* buffer to put answer */
 336                    int anslen,          /* size of answer */
 337                    u_char **answerp,
 338                    u_char **answerp2,
 339                    int *nanswerp2,
 340                    int *resplen2,
 341                    int *answerp2_malloced)
 342 {
 343         const char *cp, * const *domain;
 344         HEADER *hp = (HEADER *) answer;
 345         char tmp[NS_MAXDNAME];
 346         u_int dots;
 347         int trailing_dot, ret, saved_herrno;
 348         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 349         int tried_as_is = 0;
 350         int searched = 0;
 351
 352         __set_errno (0);
 353         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */
 354
 355         dots = 0;
 356         for (cp = name; *cp != '\0'; cp++)
 357                 dots += (*cp == '.');
 358         trailing_dot = 0;
 359         if (cp > name && *--cp == '.')
 360                 trailing_dot++;
 361
 362         /* If there aren't any dots, it could be a user-level alias. */
 363         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 364                 return (__libc_res_nquery(statp, cp, class, type, answer,
 365                                           anslen, answerp, answerp2,
 366                                           nanswerp2, resplen2, answerp2_malloced));
 367
 368 #ifdef DEBUG
 369         if (statp->options & RES_DEBUG)
 370                 printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
 371                        (int)dots,(int)statp->ndots,(int)trailing_dot,name);
 372 #endif
 373
 374         /*
 375          * If there are enough dots in the name, let's just give it a
 376          * try 'as is'. The threshold can be set with the "ndots" option.
 377          * Also, query 'as is', if there is a trailing dot in the name.
 378          */
 379         saved_herrno = -1;
 380         if (dots >= statp->ndots || trailing_dot) {
 381                 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
 382                                               answer, anslen, answerp,
 383                                               answerp2, nanswerp2, resplen2,
 384                                               answerp2_malloced);
 385                 if (ret > 0 || trailing_dot
 386                     /* If the second response is valid then we use that.  */
 387                     || (ret == 0 && answerp2 != NULL && resplen2 > 0))
 388                         return (ret);
 389                 saved_herrno = h_errno;
 390                 tried_as_is++;
 391                 if (answerp && *answerp != answer) {
 392                         answer = *answerp;
 393                         anslen = MAXPACKET;
 394                 }
 395                 if (answerp2 && *answerp2_malloced)
 396                   {
 397                     free (*answerp2);
 398                     *answerp2 = NULL;
 399                     *answerp2_malloced = 0;
 400                   }
 401         }
 402
 403         /*
 404          * We do at least one level of search if
 405          *      - there is no dot and RES_DEFNAME is set, or
 406          *      - there is at least one dot, there is no trailing dot,
 407          *        and RES_DNSRCH is set.
 408          */
 409         if ((!dots && (statp->options & RES_DEFNAMES) != 0) ||
 410             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
 411                 int done = 0;
 412
 413                 for (domain = (const char * const *)statp->dnsrch;
 414                      *domain && !done;
 415                      domain++) {
 416                         searched = 1;
 417
 418                         if (domain[0][0] == '\0' ||
 419                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 420                                 root_on_list++;
 421
 422                         ret = __libc_res_nquerydomain(statp, name, *domain,
 423                                                       class, type,
 424                                                       answer, anslen, answerp,
 425                                                       answerp2, nanswerp2,
 426                                                       resplen2, answerp2_malloced);
 427                         if (ret > 0 || (ret == 0 && answerp2 != NULL
 428                                         && resplen2 > 0))
 429                                 return (ret);
 430
 431                         if (answerp && *answerp != answer) {
 432                                 answer = *answerp;
 433                                 anslen = MAXPACKET;
 434                         }
 435                         if (answerp2 && *answerp2_malloced)
 436                           {
 437                             free (*answerp2);
 438                             *answerp2 = NULL;
 439                             *answerp2_malloced = 0;
 440                           }
 441
 442                         /*
 443                          * If no server present, give up.
 444                          * If name isn't found in this domain,
 445                          * keep trying higher domains in the search list
 446                          * (if that's enabled).
 447                          * On a NO_DATA error, keep trying, otherwise
 448                          * a wildcard entry of another type could keep us
 449                          * from finding this entry higher in the domain.
 450                          * If we get some other error (negative answer or
 451                          * server failure), then stop searching up,
 452                          * but try the input name below in case it's
 453                          * fully-qualified.
 454                          */
 455                         if (errno == ECONNREFUSED) {
 456                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 457                                 return (-1);
 458                         }
 459
 460                         switch (statp->res_h_errno) {
 461                         case NO_DATA:
 462                                 got_nodata++;
 463                                 /* FALLTHROUGH */
 464                         case HOST_NOT_FOUND:
 465                                 /* keep trying */
 466                                 break;
 467                         case TRY_AGAIN:
 468                                 if (hp->rcode == SERVFAIL) {
 469                                         /* try next search element, if any */
 470                                         got_servfail++;
 471                                         break;
 472                                 }
 473                                 /* FALLTHROUGH */
 474                         default:
 475                                 /* anything else implies that we're done */
 476                                 done++;
 477                         }
 478
 479                         /* if we got here for some reason other than DNSRCH,
 480                          * we only wanted one iteration of the loop, so stop.
 481                          */
 482                         if ((statp->options & RES_DNSRCH) == 0)
 483                                 done++;
 484                 }
 485         }
 486
 487         /*
 488          * If the query has not already been tried as is then try it
 489          * unless RES_NOTLDQUERY is set and there were no dots.
 490          */
 491         if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0)
 492             && !(tried_as_is || root_on_list)) {
 493                 ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
 494                                               answer, anslen, answerp,
 495                                               answerp2, nanswerp2, resplen2,
 496                                               answerp2_malloced);
 497                 if (ret > 0)
 498                         return (ret);
 499         }
 500
 501         /* if we got here, we didn't satisfy the search.
 502          * if we did an initial full query, return that query's H_ERRNO
 503          * (note that we wouldn't be here if that query had succeeded).
 504          * else if we ever got a nodata, send that back as the reason.
 505          * else send back meaningless H_ERRNO, that being the one from
 506          * the last DNSRCH we did.
 507          */
 508         if (answerp2 && *answerp2_malloced)
 509           {
 510             free (*answerp2);
 511             *answerp2 = NULL;
 512             *answerp2_malloced = 0;
 513           }
 514         if (saved_herrno != -1)
 515                 RES_SET_H_ERRNO(statp, saved_herrno);
 516         else if (got_nodata)
 517                 RES_SET_H_ERRNO(statp, NO_DATA);
 518         else if (got_servfail)
 519                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 520         return (-1);
 521 }
 522 libresolv_hidden_def (__libc_res_nsearch)
 523
 524 int
 525 res_nsearch(res_state statp,
 526             const char *name,   /* domain name */
 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 {
 531         return __libc_res_nsearch(statp, name, class, type, answer,
 532                                   anslen, NULL, NULL, NULL, NULL, NULL);
 533 }
 534 libresolv_hidden_def (res_nsearch)
 535
 536 /*
 537  * Perform a call on res_query on the concatenation of name and domain,
 538  * removing a trailing dot from name if domain is NULL.
 539  */
 540 static int
 541 __libc_res_nquerydomain(res_state statp,
 542                         const char *name,
 543                         const char *domain,
 544                         int class, int type,    /* class and type of query */
 545                         u_char *answer,         /* buffer to put answer */
 546                         int anslen,                     /* size of answer */
 547                         u_char **answerp,
 548                         u_char **answerp2,
 549                         int *nanswerp2,
 550                         int *resplen2,
 551                         int *answerp2_malloced)
 552 {
 553         char nbuf[MAXDNAME];
 554         const char *longname = nbuf;
 555         size_t n, d;
 556
 557 #ifdef DEBUG
 558         if (statp->options & RES_DEBUG)
 559                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 560                        name, domain?domain:"<Nil>", class, type);
 561 #endif
 562         if (domain == NULL) {
 563                 /*
 564                  * Check for trailing '.';
 565                  * copy without '.' if present.
 566                  */
 567                 n = strlen(name);
 568
 569                 /* Decrement N prior to checking it against MAXDNAME
 570                    so that we detect a wrap to SIZE_MAX and return
 571                    a reasonable error.  */
 572                 n--;
 573                 if (n >= MAXDNAME - 1) {
 574                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 575                         return (-1);
 576                 }
 577                 if (name[n] == '.') {
 578                         strncpy(nbuf, name, n);
 579                         nbuf[n] = '\0';
 580                 } else
 581                         longname = name;
 582         } else {
 583                 n = strlen(name);
 584                 d = strlen(domain);
 585                 if (n + d + 1 >= MAXDNAME) {
 586                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 587                         return (-1);
 588                 }
 589                 sprintf(nbuf, "%s.%s", name, domain);
 590         }
 591         return (__libc_res_nquery(statp, longname, class, type, answer,
 592                                   anslen, answerp, answerp2, nanswerp2,
 593                                   resplen2, answerp2_malloced));
 594 }
 595
 596 int
 597 res_nquerydomain(res_state statp,
 598             const char *name,
 599             const char *domain,
 600             int class, int type,        /* class and type of query */
 601             u_char *answer,             /* buffer to put answer */
 602             int anslen)         /* size of answer */
 603 {
 604         return __libc_res_nquerydomain(statp, name, domain, class, type,
 605                                        answer, anslen, NULL, NULL, NULL, NULL,
 606                                        NULL);
 607 }
 608 libresolv_hidden_def (res_nquerydomain)
 609
 610 const char *
 611 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 612         char *file, *cp1, *cp2;
 613         char buf[BUFSIZ];
 614         FILE *fp;
 615
 616         if (statp->options & RES_NOALIASES)
 617                 return (NULL);
 618         file = getenv("HOSTALIASES");
 619         if (file == NULL || (fp = fopen(file, "rce")) == NULL)
 620                 return (NULL);
 621         setbuf(fp, NULL);
 622         buf[sizeof(buf) - 1] = '\0';
 623         while (fgets(buf, sizeof(buf), fp)) {
 624                 for (cp1 = buf; *cp1 && !isspace(*cp1); ++cp1)
 625                         ;
 626                 if (!*cp1)
 627                         break;
 628                 *cp1 = '\0';
 629                 if (ns_samename(buf, name) == 1) {
 630                         while (isspace(*++cp1))
 631                                 ;
 632                         if (!*cp1)
 633                                 break;
 634                         for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
 635                                 ;
 636                         *cp2 = '\0';
 637                         strncpy(dst, cp1, siz - 1);
 638                         dst[siz - 1] = '\0';
 639                         fclose(fp);
 640                         return (dst);
 641                 }
 642         }
 643         fclose(fp);
 644         return (NULL);
 645 }
 646 libresolv_hidden_def (res_hostalias)