lib/libc/resolv/res_query.c

   1 /*      $NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $  */
   2
   3 /*
   4  * Portions Copyright (C) 2004, 2005, 2008  Internet Systems Consortium, Inc. ("ISC")
   5  * Portions Copyright (C) 1996-2001, 2003  Internet Software Consortium.
   6  *
   7  * Permission to use, copy, modify, and/or distribute this software for any
   8  * purpose with or without fee is hereby granted, provided that the above
   9  * copyright notice and this permission notice appear in all copies.
  10  *
  11  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
  12  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  13  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
  14  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
  15  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
  16  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
  17  * PERFORMANCE OF THIS SOFTWARE.
  18  */
  19
  20 /*
  21  * Copyright (c) 1988, 1993
  22  *    The Regents of the University of California.  All rights reserved.
  23  *
  24  * Redistribution and use in source and binary forms, with or without
  25  * modification, are permitted provided that the following conditions
  26  * are met:
  27  * 1. Redistributions of source code must retain the above copyright
  28  *    notice, this list of conditions and the following disclaimer.
  29  * 2. Redistributions in binary form must reproduce the above copyright
  30  *    notice, this list of conditions and the following disclaimer in the
  31  *    documentation and/or other materials provided with the distribution.
  32  * 3. All advertising materials mentioning features or use of this software
  33  *    must display the following acknowledgement:
  34  *      This product includes software developed by the University of
  35  *      California, Berkeley and its contributors.
  36  * 4. Neither the name of the University nor the names of its contributors
  37  *    may be used to endorse or promote products derived from this software
  38  *    without specific prior written permission.
  39  *
  40  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  41  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  42  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  43  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  44  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  45  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  46  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  47  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  48  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  49  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  50  * SUCH DAMAGE.
  51  */
  52
  53 /*
  54  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  55  *
  56  * Permission to use, copy, modify, and distribute this software for any
  57  * purpose with or without fee is hereby granted, provided that the above
  58  * copyright notice and this permission notice appear in all copies, and that
  59  * the name of Digital Equipment Corporation not be used in advertising or
  60  * publicity pertaining to distribution of the document or software without
  61  * specific, written prior permission.
  62  *
  63  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  64  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  65  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  66  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  67  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  68  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  69  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  70  * SOFTWARE.
  71  */
  72
  73 /*
  74  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
  75  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  76  *
  77  * Permission to use, copy, modify, and distribute this software for any
  78  * purpose with or without fee is hereby granted, provided that the above
  79  * copyright notice and this permission notice appear in all copies.
  80  *
  81  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  82  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  83  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  84  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  85  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  86  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  87  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  88  */
  89
  90 #include <sys/cdefs.h>
  91 #if defined(LIBC_SCCS) && !defined(lint)
  92 #ifdef notdef
  93 static const char sccsid[] = "@(#)res_query.c   8.1 (Berkeley) 6/4/93";
  94 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp";
  95 #else
  96 __RCSID("$NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $");
  97 #endif
  98 #endif /* LIBC_SCCS and not lint */
  99
 100 #include "port_before.h"
 101
 102 #include "namespace.h"
 103 #include <sys/types.h>
 104 #include <sys/param.h>
 105 #include <netinet/in.h>
 106 #include <arpa/inet.h>
 107 #include <arpa/nameser.h>
 108 #include <ctype.h>
 109 #include <errno.h>
 110 #include <netdb.h>
 111 #include <resolv.h>
 112 #include <stdio.h>
 113 #include <stdlib.h>
 114 #include <unistd.h>
 115 #include <string.h>
 116 #include "port_after.h"
 117
 118 #if 0
 119 #ifdef __weak_alias
 120 __weak_alias(res_nquery,_res_nquery)
 121 __weak_alias(res_nsearch,_res_nsearch)
 122 __weak_alias(res_nquerydomain,__res_nquerydomain)
 123 __weak_alias(res_hostalias,__res_hostalias)
 124 #endif
 125 #endif
 126
 127 /* Options.  Leave them on. */
 128 #ifndef DEBUG
 129 #define DEBUG
 130 #endif
 131
 132 #if PACKETSZ > 1024
 133 #define MAXPACKET       PACKETSZ
 134 #else
 135 #define MAXPACKET       1024
 136 #endif
 137
 138 /*%
 139  * Formulate a normal query, send, and await answer.
 140  * Returned answer is placed in supplied buffer "answer".
 141  * Perform preliminary check of answer, returning success only
 142  * if no error is indicated and the answer count is nonzero.
 143  * Return the size of the response on success, -1 on error.
 144  * Error number is left in H_ERRNO.
 145  *
 146  * Caller must parse answer and determine whether it answers the question.
 147  */
 148 int
 149 res_nquery(res_state statp,
 150            const char *name,    /*%< domain name */
 151            int class, int type, /*%< class and type of query */
 152            u_char *answer,      /*%< buffer to put answer */
 153            int anslen)          /*%< size of answer buffer */
 154 {
 155         u_char buf[MAXPACKET];
 156         HEADER *hp = (HEADER *)(void *)answer;
 157         u_int oflags;
 158         u_char *rdata;
 159         int n;
 160
 161         oflags = statp->_flags;
 162
 163 again:
 164         hp->rcode = NOERROR;    /*%< default */
 165 #ifdef DEBUG
 166         if (statp->options & RES_DEBUG)
 167                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 168 #endif
 169
 170         n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 171                          buf, sizeof(buf));
 172 #ifdef RES_USE_EDNS0
 173         if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
 174             (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) {
 175                 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
 176                 rdata = &buf[n];
 177                 if (n > 0 && (statp->options & RES_NSID) != 0U) {
 178                         n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
 179                                            NS_OPT_NSID, 0, NULL);
 180                 }
 181         }
 182 #endif
 183         if (n <= 0) {
 184 #ifdef DEBUG
 185                 if (statp->options & RES_DEBUG)
 186                         printf(";; res_query: mkquery failed\n");
 187 #endif
 188                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 189                 return (n);
 190         }
 191
 192         n = res_nsend(statp, buf, n, answer, anslen);
 193         if (n < 0) {
 194 #ifdef RES_USE_EDNS0
 195                 /* if the query choked with EDNS0, retry without EDNS0 */
 196                 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
 197                     ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 198                         statp->_flags |= RES_F_EDNS0ERR;
 199                         if (statp->options & RES_DEBUG)
 200                                 printf(";; res_nquery: retry without EDNS0\n");
 201                         goto again;
 202                 }
 203 #endif
 204 #ifdef DEBUG
 205                 if (statp->options & RES_DEBUG)
 206                         printf(";; res_query: send error\n");
 207 #endif
 208                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 209                 return (n);
 210         }
 211
 212         if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
 213 #ifdef DEBUG
 214                 if (statp->options & RES_DEBUG)
 215                         printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
 216                                p_rcode(hp->rcode),
 217                                ntohs(hp->ancount),
 218                                ntohs(hp->nscount),
 219                                ntohs(hp->arcount));
 220 #endif
 221                 switch (hp->rcode) {
 222                 case NXDOMAIN:
 223                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 224                         break;
 225                 case SERVFAIL:
 226                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 227                         break;
 228                 case NOERROR:
 229                         RES_SET_H_ERRNO(statp, NO_DATA);
 230                         break;
 231                 case FORMERR:
 232                 case NOTIMP:
 233                 case REFUSED:
 234                 default:
 235                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 236                         break;
 237                 }
 238                 return (-1);
 239         }
 240         return (n);
 241 }
 242
 243 /*%
 244  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 245  * Return the size of the response on success, -1 on error.
 246  * If enabled, implement search rules until answer or unrecoverable failure
 247  * is detected.  Error code, if any, is left in H_ERRNO.
 248  */
 249 int
 250 res_nsearch(res_state statp,
 251             const char *name,   /*%< domain name */
 252             int class, int type,        /*%< class and type of query */
 253             u_char *answer,     /*%< buffer to put answer */
 254             int anslen)         /*%< size of answer */
 255 {
 256         const char *cp, * const *domain;
 257         HEADER *hp = (HEADER *)(void *)answer;
 258         char tmp[NS_MAXDNAME];
 259         u_int dots;
 260         int trailing_dot, ret, saved_herrno;
 261         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 262         int tried_as_is = 0;
 263         int searched = 0;
 264
 265         errno = 0;
 266         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /*%< True if we never query. */
 267         dots = 0;
 268         for (cp = name; *cp != '\0'; cp++)
 269                 dots += (*cp == '.');
 270         trailing_dot = 0;
 271         if (cp > name && *--cp == '.')
 272                 trailing_dot++;
 273
 274         /* If there aren't any dots, it could be a user-level alias. */
 275         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 276                 return (res_nquery(statp, cp, class, type, answer, anslen));
 277
 278         /*
 279          * If there are enough dots in the name, let's just give it a
 280          * try 'as is'. The threshold can be set with the "ndots" option.
 281          * Also, query 'as is', if there is a trailing dot in the name.
 282          */
 283         saved_herrno = -1;
 284         if (dots >= statp->ndots || trailing_dot) {
 285                 ret = res_nquerydomain(statp, name, NULL, class, type,
 286                                          answer, anslen);
 287                 if (ret > 0 || trailing_dot)
 288                         return (ret);
 289                 saved_herrno = statp->res_h_errno;
 290                 tried_as_is++;
 291         }
 292
 293         /*
 294          * We do at least one level of search if
 295          *      - there is no dot and RES_DEFNAME is set, or
 296          *      - there is at least one dot, there is no trailing dot,
 297          *        and RES_DNSRCH is set.
 298          */
 299         if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
 300             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
 301                 int done = 0;
 302
 303                 for (domain = (const char * const *)statp->dnsrch;
 304                      *domain && !done;
 305                      domain++) {
 306                         searched = 1;
 307
 308                         if (domain[0][0] == '\0' ||
 309                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 310                                 root_on_list++;
 311
 312                         ret = res_nquerydomain(statp, name, *domain,
 313                                                class, type,
 314                                                answer, anslen);
 315                         if (ret > 0)
 316                                 return (ret);
 317
 318                         /*
 319                          * If no server present, give up.
 320                          * If name isn't found in this domain,
 321                          * keep trying higher domains in the search list
 322                          * (if that's enabled).
 323                          * On a NO_DATA error, keep trying, otherwise
 324                          * a wildcard entry of another type could keep us
 325                          * from finding this entry higher in the domain.
 326                          * If we get some other error (negative answer or
 327                          * server failure), then stop searching up,
 328                          * but try the input name below in case it's
 329                          * fully-qualified.
 330                          */
 331                         if (errno == ECONNREFUSED) {
 332                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 333                                 return (-1);
 334                         }
 335
 336                         switch (statp->res_h_errno) {
 337                         case NO_DATA:
 338                                 got_nodata++;
 339                                 /* FALLTHROUGH */
 340                         case HOST_NOT_FOUND:
 341                                 /* keep trying */
 342                                 break;
 343                         case TRY_AGAIN:
 344                                 if (hp->rcode == SERVFAIL) {
 345                                         /* try next search element, if any */
 346                                         got_servfail++;
 347                                         break;
 348                                 }
 349                                 /* FALLTHROUGH */
 350                         default:
 351                                 /* anything else implies that we're done */
 352                                 done++;
 353                         }
 354
 355                         /* if we got here for some reason other than DNSRCH,
 356                          * we only wanted one iteration of the loop, so stop.
 357                          */
 358                         if ((statp->options & RES_DNSRCH) == 0U)
 359                                 done++;
 360                 }
 361         }
 362
 363         /*
 364          * If the query has not already been tried as is then try it
 365          * unless RES_NOTLDQUERY is set and there were no dots.
 366          */
 367         if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
 368             !(tried_as_is || root_on_list)) {
 369                 ret = res_nquerydomain(statp, name, NULL, class, type,
 370                                        answer, anslen);
 371                 if (ret > 0)
 372                         return (ret);
 373         }
 374
 375         /* if we got here, we didn't satisfy the search.
 376          * if we did an initial full query, return that query's H_ERRNO
 377          * (note that we wouldn't be here if that query had succeeded).
 378          * else if we ever got a nodata, send that back as the reason.
 379          * else send back meaningless H_ERRNO, that being the one from
 380          * the last DNSRCH we did.
 381          */
 382         if (saved_herrno != -1)
 383                 RES_SET_H_ERRNO(statp, saved_herrno);
 384         else if (got_nodata)
 385                 RES_SET_H_ERRNO(statp, NO_DATA);
 386         else if (got_servfail)
 387                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 388         return (-1);
 389 }
 390
 391 /*%
 392  * Perform a call on res_query on the concatenation of name and domain,
 393  * removing a trailing dot from name if domain is NULL.
 394  */
 395 int
 396 res_nquerydomain(res_state statp,
 397             const char *name,
 398             const char *domain,
 399             int class, int type,        /*%< class and type of query */
 400             u_char *answer,             /*%< buffer to put answer */
 401             int anslen)         /*%< size of answer */
 402 {
 403         char nbuf[MAXDNAME];
 404         const char *longname = nbuf;
 405         int n, d;
 406
 407 #ifdef DEBUG
 408         if (statp->options & RES_DEBUG)
 409                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 410                        name, domain?domain:"<Nil>", class, type);
 411 #endif
 412         if (domain == NULL) {
 413                 /*
 414                  * Check for trailing '.';
 415                  * copy without '.' if present.
 416                  */
 417                 n = strlen(name);
 418                 if (n >= MAXDNAME) {
 419                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 420                         return (-1);
 421                 }
 422                 n--;
 423                 if (n >= 0 && name[n] == '.') {
 424                         strncpy(nbuf, name, (size_t)n);
 425                         nbuf[n] = '\0';
 426                 } else
 427                         longname = name;
 428         } else {
 429                 n = strlen(name);
 430                 d = strlen(domain);
 431                 if (n + d + 1 >= MAXDNAME) {
 432                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 433                         return (-1);
 434                 }
 435                 sprintf(nbuf, "%s.%s", name, domain);
 436         }
 437         return (res_nquery(statp, longname, class, type, answer, anslen));
 438 }
 439
 440 const char *
 441 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 442         char *file, *cp1, *cp2;
 443         char buf[BUFSIZ];
 444         FILE *fp;
 445
 446         if (statp->options & RES_NOALIASES)
 447                 return (NULL);
 448         /*
 449          * forbid hostaliases for setuid binary, due to possible security
 450          * breach.
 451          */
 452         if (issetugid())
 453                 return (NULL);
 454         file = getenv("HOSTALIASES");
 455         if (file == NULL || (fp = fopen(file, "r")) == NULL)
 456                 return (NULL);
 457         buf[sizeof(buf) - 1] = '\0';
 458         while (fgets(buf, sizeof(buf), fp)) {
 459                 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
 460                         ;
 461                 if (!*cp1)
 462                         break;
 463                 *cp1 = '\0';
 464                 if (ns_samename(buf, name) == 1) {
 465                         while (isspace((unsigned char)*++cp1))
 466                                 ;
 467                         if (!*cp1)
 468                                 break;
 469                         for (cp2 = cp1 + 1; *cp2 &&
 470                              !isspace((unsigned char)*cp2); ++cp2)
 471                                 ;
 472                         *cp2 = '\0';
 473                         strncpy(dst, cp1, siz - 1);
 474                         dst[siz - 1] = '\0';
 475                         fclose(fp);
 476                         return (dst);
 477                 }
 478         }
 479         fclose(fp);
 480         return (NULL);
 481 }
 482
 483 /*! \file */