external/bsd/libbind/dist/resolv/res_query.c

   1 /*      $NetBSD$        */
   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 #if defined(LIBC_SCCS) && !defined(lint)
  74 static const char sccsid[] = "@(#)res_query.c   8.1 (Berkeley) 6/4/93";
  75 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp";
  76 #endif /* LIBC_SCCS and not lint */
  77
  78 #include "port_before.h"
  79 #include <sys/types.h>
  80 #include <sys/param.h>
  81 #include <netinet/in.h>
  82 #include <arpa/inet.h>
  83 #include <arpa/nameser.h>
  84 #include <ctype.h>
  85 #include <errno.h>
  86 #include <netdb.h>
  87 #include <resolv.h>
  88 #include <stdio.h>
  89 #include <stdlib.h>
  90 #include <string.h>
  91 #include "port_after.h"
  92
  93 /* Options.  Leave them on. */
  94 #define DEBUG
  95
  96 #if PACKETSZ > 1024
  97 #define MAXPACKET       PACKETSZ
  98 #else
  99 #define MAXPACKET       1024
 100 #endif
 101
 102 /*%
 103  * Formulate a normal query, send, and await answer.
 104  * Returned answer is placed in supplied buffer "answer".
 105  * Perform preliminary check of answer, returning success only
 106  * if no error is indicated and the answer count is nonzero.
 107  * Return the size of the response on success, -1 on error.
 108  * Error number is left in H_ERRNO.
 109  *
 110  * Caller must parse answer and determine whether it answers the question.
 111  */
 112 int
 113 res_nquery(res_state statp,
 114            const char *name,    /*%< domain name */
 115            int class, int type, /*%< class and type of query */
 116            u_char *answer,      /*%< buffer to put answer */
 117            int anslen)          /*%< size of answer buffer */
 118 {
 119         u_char buf[MAXPACKET];
 120         HEADER *hp = (HEADER *) answer;
 121         u_int oflags;
 122         u_char *rdata;
 123         int n;
 124
 125         oflags = statp->_flags;
 126
 127 again:
 128         hp->rcode = NOERROR;    /*%< default */
 129 #ifdef DEBUG
 130         if (statp->options & RES_DEBUG)
 131                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 132 #endif
 133
 134         n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 135                          buf, sizeof(buf));
 136 #ifdef RES_USE_EDNS0
 137         if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
 138             (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
 139                 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
 140                 rdata = &buf[n];
 141                 if (n > 0 && (statp->options & RES_NSID) != 0U) {
 142                         n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
 143                                            NS_OPT_NSID, 0, NULL);
 144                 }
 145         }
 146 #endif
 147         if (n <= 0) {
 148 #ifdef DEBUG
 149                 if (statp->options & RES_DEBUG)
 150                         printf(";; res_query: mkquery failed\n");
 151 #endif
 152                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 153                 return (n);
 154         }
 155
 156         n = res_nsend(statp, buf, n, answer, anslen);
 157         if (n < 0) {
 158 #ifdef RES_USE_EDNS0
 159                 /* if the query choked with EDNS0, retry without EDNS0 */
 160                 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
 161                     ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 162                         statp->_flags |= RES_F_EDNS0ERR;
 163                         if (statp->options & RES_DEBUG)
 164                                 printf(";; res_nquery: retry without EDNS0\n");
 165                         goto again;
 166                 }
 167 #endif
 168 #ifdef DEBUG
 169                 if (statp->options & RES_DEBUG)
 170                         printf(";; res_query: send error\n");
 171 #endif
 172                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 173                 return (n);
 174         }
 175
 176         if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
 177 #ifdef DEBUG
 178                 if (statp->options & RES_DEBUG)
 179                         printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
 180                                p_rcode(hp->rcode),
 181                                ntohs(hp->ancount),
 182                                ntohs(hp->nscount),
 183                                ntohs(hp->arcount));
 184 #endif
 185                 switch (hp->rcode) {
 186                 case NXDOMAIN:
 187                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 188                         break;
 189                 case SERVFAIL:
 190                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 191                         break;
 192                 case NOERROR:
 193                         RES_SET_H_ERRNO(statp, NO_DATA);
 194                         break;
 195                 case FORMERR:
 196                 case NOTIMP:
 197                 case REFUSED:
 198                 default:
 199                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 200                         break;
 201                 }
 202                 return (-1);
 203         }
 204         return (n);
 205 }
 206
 207 /*%
 208  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 209  * Return the size of the response on success, -1 on error.
 210  * If enabled, implement search rules until answer or unrecoverable failure
 211  * is detected.  Error code, if any, is left in H_ERRNO.
 212  */
 213 int
 214 res_nsearch(res_state statp,
 215             const char *name,   /*%< domain name */
 216             int class, int type,        /*%< class and type of query */
 217             u_char *answer,     /*%< buffer to put answer */
 218             int anslen)         /*%< size of answer */
 219 {
 220         const char *cp, * const *domain;
 221         HEADER *hp = (HEADER *) answer;
 222         char tmp[NS_MAXDNAME];
 223         u_int dots;
 224         int trailing_dot, ret, saved_herrno;
 225         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 226         int tried_as_is = 0;
 227         int searched = 0;
 228
 229         errno = 0;
 230         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /*%< True if we never query. */
 231         dots = 0;
 232         for (cp = name; *cp != '\0'; cp++)
 233                 dots += (*cp == '.');
 234         trailing_dot = 0;
 235         if (cp > name && *--cp == '.')
 236                 trailing_dot++;
 237
 238         /* If there aren't any dots, it could be a user-level alias. */
 239         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 240                 return (res_nquery(statp, cp, class, type, answer, anslen));
 241
 242         /*
 243          * If there are enough dots in the name, let's just give it a
 244          * try 'as is'. The threshold can be set with the "ndots" option.
 245          * Also, query 'as is', if there is a trailing dot in the name.
 246          */
 247         saved_herrno = -1;
 248         if (dots >= statp->ndots || trailing_dot) {
 249                 ret = res_nquerydomain(statp, name, NULL, class, type,
 250                                          answer, anslen);
 251                 if (ret > 0 || trailing_dot)
 252                         return (ret);
 253                 saved_herrno = statp->res_h_errno;
 254                 tried_as_is++;
 255         }
 256
 257         /*
 258          * We do at least one level of search if
 259          *      - there is no dot and RES_DEFNAME is set, or
 260          *      - there is at least one dot, there is no trailing dot,
 261          *        and RES_DNSRCH is set.
 262          */
 263         if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
 264             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
 265                 int done = 0;
 266
 267                 for (domain = (const char * const *)statp->dnsrch;
 268                      *domain && !done;
 269                      domain++) {
 270                         searched = 1;
 271
 272                         if (domain[0][0] == '\0' ||
 273                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 274                                 root_on_list++;
 275
 276                         ret = res_nquerydomain(statp, name, *domain,
 277                                                class, type,
 278                                                answer, anslen);
 279                         if (ret > 0)
 280                                 return (ret);
 281
 282                         /*
 283                          * If no server present, give up.
 284                          * If name isn't found in this domain,
 285                          * keep trying higher domains in the search list
 286                          * (if that's enabled).
 287                          * On a NO_DATA error, keep trying, otherwise
 288                          * a wildcard entry of another type could keep us
 289                          * from finding this entry higher in the domain.
 290                          * If we get some other error (negative answer or
 291                          * server failure), then stop searching up,
 292                          * but try the input name below in case it's
 293                          * fully-qualified.
 294                          */
 295                         if (errno == ECONNREFUSED) {
 296                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 297                                 return (-1);
 298                         }
 299
 300                         switch (statp->res_h_errno) {
 301                         case NO_DATA:
 302                                 got_nodata++;
 303                                 /* FALLTHROUGH */
 304                         case HOST_NOT_FOUND:
 305                                 /* keep trying */
 306                                 break;
 307                         case TRY_AGAIN:
 308                                 if (hp->rcode == SERVFAIL) {
 309                                         /* try next search element, if any */
 310                                         got_servfail++;
 311                                         break;
 312                                 }
 313                                 /* FALLTHROUGH */
 314                         default:
 315                                 /* anything else implies that we're done */
 316                                 done++;
 317                         }
 318
 319                         /* if we got here for some reason other than DNSRCH,
 320                          * we only wanted one iteration of the loop, so stop.
 321                          */
 322                         if ((statp->options & RES_DNSRCH) == 0U)
 323                                 done++;
 324                 }
 325         }
 326
 327         /*
 328          * If the query has not already been tried as is then try it
 329          * unless RES_NOTLDQUERY is set and there were no dots.
 330          */
 331         if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
 332             !(tried_as_is || root_on_list)) {
 333                 ret = res_nquerydomain(statp, name, NULL, class, type,
 334                                        answer, anslen);
 335                 if (ret > 0)
 336                         return (ret);
 337         }
 338
 339         /* if we got here, we didn't satisfy the search.
 340          * if we did an initial full query, return that query's H_ERRNO
 341          * (note that we wouldn't be here if that query had succeeded).
 342          * else if we ever got a nodata, send that back as the reason.
 343          * else send back meaningless H_ERRNO, that being the one from
 344          * the last DNSRCH we did.
 345          */
 346         if (saved_herrno != -1)
 347                 RES_SET_H_ERRNO(statp, saved_herrno);
 348         else if (got_nodata)
 349                 RES_SET_H_ERRNO(statp, NO_DATA);
 350         else if (got_servfail)
 351                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 352         return (-1);
 353 }
 354
 355 /*%
 356  * Perform a call on res_query on the concatenation of name and domain,
 357  * removing a trailing dot from name if domain is NULL.
 358  */
 359 int
 360 res_nquerydomain(res_state statp,
 361             const char *name,
 362             const char *domain,
 363             int class, int type,        /*%< class and type of query */
 364             u_char *answer,             /*%< buffer to put answer */
 365             int anslen)         /*%< size of answer */
 366 {
 367         char nbuf[MAXDNAME];
 368         const char *longname = nbuf;
 369         int n, d;
 370
 371 #ifdef DEBUG
 372         if (statp->options & RES_DEBUG)
 373                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 374                        name, domain?domain:"<Nil>", class, type);
 375 #endif
 376         if (domain == NULL) {
 377                 /*
 378                  * Check for trailing '.';
 379                  * copy without '.' if present.
 380                  */
 381                 n = strlen(name);
 382                 if (n >= MAXDNAME) {
 383                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 384                         return (-1);
 385                 }
 386                 n--;
 387                 if (n >= 0 && name[n] == '.') {
 388                         strncpy(nbuf, name, n);
 389                         nbuf[n] = '\0';
 390                 } else
 391                         longname = name;
 392         } else {
 393                 n = strlen(name);
 394                 d = strlen(domain);
 395                 if (n + d + 1 >= MAXDNAME) {
 396                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 397                         return (-1);
 398                 }
 399                 sprintf(nbuf, "%s.%s", name, domain);
 400         }
 401         return (res_nquery(statp, longname, class, type, answer, anslen));
 402 }
 403
 404 const char *
 405 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 406         char *file, *cp1, *cp2;
 407         char buf[BUFSIZ];
 408         FILE *fp;
 409
 410         if (statp->options & RES_NOALIASES)
 411                 return (NULL);
 412         file = getenv("HOSTALIASES");
 413         if (file == NULL || (fp = fopen(file, "r")) == NULL)
 414                 return (NULL);
 415         setbuf(fp, NULL);
 416         buf[sizeof(buf) - 1] = '\0';
 417         while (fgets(buf, sizeof(buf), fp)) {
 418                 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
 419                         ;
 420                 if (!*cp1)
 421                         break;
 422                 *cp1 = '\0';
 423                 if (ns_samename(buf, name) == 1) {
 424                         while (isspace((unsigned char)*++cp1))
 425                                 ;
 426                         if (!*cp1)
 427                                 break;
 428                         for (cp2 = cp1 + 1; *cp2 &&
 429                              !isspace((unsigned char)*cp2); ++cp2)
 430                                 ;
 431                         *cp2 = '\0';
 432                         strncpy(dst, cp1, siz - 1);
 433                         dst[siz - 1] = '\0';
 434                         fclose(fp);
 435                         return (dst);
 436                 }
 437         }
 438         fclose(fp);
 439         return (NULL);
 440 }
 441
 442 /*! \file */