contrib/bind-9.2.4rc7/lib/bind/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  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 /*
  35  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  36  *
  37  * Permission to use, copy, modify, and distribute this software for any
  38  * purpose with or without fee is hereby granted, provided that the above
  39  * copyright notice and this permission notice appear in all copies, and that
  40  * the name of Digital Equipment Corporation not be used in advertising or
  41  * publicity pertaining to distribution of the document or software without
  42  * specific, written prior permission.
  43  *
  44  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  45  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  46  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  47  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  48  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  49  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  50  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  51  * SOFTWARE.
  52  */
  53
  54 /*
  55  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
  56  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
  57  *
  58  * Permission to use, copy, modify, and distribute this software for any
  59  * purpose with or without fee is hereby granted, provided that the above
  60  * copyright notice and this permission notice appear in all copies.
  61  *
  62  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
  63  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  64  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
  65  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  66  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  67  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
  68  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  69  */
  70
  71 #if defined(LIBC_SCCS) && !defined(lint)
  72 static const char sccsid[] = "@(#)res_query.c   8.1 (Berkeley) 6/4/93";
  73 static const char rcsid[] = "$Id: res_query.c,v 1.2.2.5 2004/03/16 12:35:36 marka Exp $";
  74 #endif /* LIBC_SCCS and not lint */
  75
  76 #include "port_before.h"
  77 #include <sys/types.h>
  78 #include <sys/param.h>
  79 #include <netinet/in.h>
  80 #include <arpa/inet.h>
  81 #include <arpa/nameser.h>
  82 #include <ctype.h>
  83 #include <errno.h>
  84 #include <netdb.h>
  85 #include <resolv.h>
  86 #include <stdio.h>
  87 #include <stdlib.h>
  88 #include <string.h>
  89 #include "port_after.h"
  90
  91 /* Options.  Leave them on. */
  92 #define DEBUG
  93
  94 #if PACKETSZ > 1024
  95 #define MAXPACKET       PACKETSZ
  96 #else
  97 #define MAXPACKET       1024
  98 #endif
  99
 100 /*
 101  * Formulate a normal query, send, and await answer.
 102  * Returned answer is placed in supplied buffer "answer".
 103  * Perform preliminary check of answer, returning success only
 104  * if no error is indicated and the answer count is nonzero.
 105  * Return the size of the response on success, -1 on error.
 106  * Error number is left in H_ERRNO.
 107  *
 108  * Caller must parse answer and determine whether it answers the question.
 109  */
 110 int
 111 res_nquery(res_state statp,
 112            const char *name,    /* domain name */
 113            int class, int type, /* class and type of query */
 114            u_char *answer,      /* buffer to put answer */
 115            int anslen)          /* size of answer buffer */
 116 {
 117         u_char buf[MAXPACKET];
 118         HEADER *hp = (HEADER *) answer;
 119         int n;
 120         u_int oflags;
 121
 122         oflags = statp->_flags;
 123
 124 again:
 125         hp->rcode = NOERROR;    /* default */
 126
 127 #ifdef DEBUG
 128         if (statp->options & RES_DEBUG)
 129                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 130 #endif
 131
 132         n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 133                          buf, sizeof(buf));
 134 #ifdef RES_USE_EDNS0
 135         if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
 136             (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U)
 137                 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
 138 #endif
 139         if (n <= 0) {
 140 #ifdef DEBUG
 141                 if (statp->options & RES_DEBUG)
 142                         printf(";; res_query: mkquery failed\n");
 143 #endif
 144                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 145                 return (n);
 146         }
 147         n = res_nsend(statp, buf, n, answer, anslen);
 148         if (n < 0) {
 149 #ifdef RES_USE_EDNS0
 150                 /* if the query choked with EDNS0, retry without EDNS0 */
 151                 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
 152                     ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 153                         statp->_flags |= RES_F_EDNS0ERR;
 154                         if (statp->options & RES_DEBUG)
 155                                 printf(";; res_nquery: retry without EDNS0\n");
 156                         goto again;
 157                 }
 158 #endif
 159 #ifdef DEBUG
 160                 if (statp->options & RES_DEBUG)
 161                         printf(";; res_query: send error\n");
 162 #endif
 163                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 164                 return (n);
 165         }
 166
 167         if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
 168 #ifdef DEBUG
 169                 if (statp->options & RES_DEBUG)
 170                         printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
 171                                p_rcode(hp->rcode),
 172                                ntohs(hp->ancount),
 173                                ntohs(hp->nscount),
 174                                ntohs(hp->arcount));
 175 #endif
 176                 switch (hp->rcode) {
 177                 case NXDOMAIN:
 178                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 179                         break;
 180                 case SERVFAIL:
 181                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 182                         break;
 183                 case NOERROR:
 184                         RES_SET_H_ERRNO(statp, NO_DATA);
 185                         break;
 186                 case FORMERR:
 187                 case NOTIMP:
 188                 case REFUSED:
 189                 default:
 190                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 191                         break;
 192                 }
 193                 return (-1);
 194         }
 195         return (n);
 196 }
 197
 198 /*
 199  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 200  * Return the size of the response on success, -1 on error.
 201  * If enabled, implement search rules until answer or unrecoverable failure
 202  * is detected.  Error code, if any, is left in H_ERRNO.
 203  */
 204 int
 205 res_nsearch(res_state statp,
 206             const char *name,   /* domain name */
 207             int class, int type,        /* class and type of query */
 208             u_char *answer,     /* buffer to put answer */
 209             int anslen)         /* size of answer */
 210 {
 211         const char *cp, * const *domain;
 212         HEADER *hp = (HEADER *) answer;
 213         char tmp[NS_MAXDNAME];
 214         u_int dots;
 215         int trailing_dot, ret, saved_herrno;
 216         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 217         int tried_as_is = 0;
 218         int searched = 0;
 219
 220         errno = 0;
 221         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /* True if we never query. */
 222
 223         dots = 0;
 224         for (cp = name; *cp != '\0'; cp++)
 225                 dots += (*cp == '.');
 226         trailing_dot = 0;
 227         if (cp > name && *--cp == '.')
 228                 trailing_dot++;
 229
 230         /* If there aren't any dots, it could be a user-level alias. */
 231         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 232                 return (res_nquery(statp, cp, class, type, answer, anslen));
 233
 234         /*
 235          * If there are enough dots in the name, let's just give it a
 236          * try 'as is'. The threshold can be set with the "ndots" option.
 237          * Also, query 'as is', if there is a trailing dot in the name.
 238          */
 239         saved_herrno = -1;
 240         if (dots >= statp->ndots || trailing_dot) {
 241                 ret = res_nquerydomain(statp, name, NULL, class, type,
 242                                          answer, anslen);
 243                 if (ret > 0 || trailing_dot)
 244                         return (ret);
 245                 saved_herrno = statp->res_h_errno;
 246                 tried_as_is++;
 247         }
 248
 249         /*
 250          * We do at least one level of search if
 251          *      - there is no dot and RES_DEFNAME is set, or
 252          *      - there is at least one dot, there is no trailing dot,
 253          *        and RES_DNSRCH is set.
 254          */
 255         if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
 256             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
 257                 int done = 0;
 258
 259                 for (domain = (const char * const *)statp->dnsrch;
 260                      *domain && !done;
 261                      domain++) {
 262                         searched = 1;
 263
 264                         if (domain[0][0] == '\0' ||
 265                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 266                                 root_on_list++;
 267
 268                         ret = res_nquerydomain(statp, name, *domain,
 269                                                class, type,
 270                                                answer, anslen);
 271                         if (ret > 0)
 272                                 return (ret);
 273
 274                         /*
 275                          * If no server present, give up.
 276                          * If name isn't found in this domain,
 277                          * keep trying higher domains in the search list
 278                          * (if that's enabled).
 279                          * On a NO_DATA error, keep trying, otherwise
 280                          * a wildcard entry of another type could keep us
 281                          * from finding this entry higher in the domain.
 282                          * If we get some other error (negative answer or
 283                          * server failure), then stop searching up,
 284                          * but try the input name below in case it's
 285                          * fully-qualified.
 286                          */
 287                         if (errno == ECONNREFUSED) {
 288                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 289                                 return (-1);
 290                         }
 291
 292                         switch (statp->res_h_errno) {
 293                         case NO_DATA:
 294                                 got_nodata++;
 295                                 /* FALLTHROUGH */
 296                         case HOST_NOT_FOUND:
 297                                 /* keep trying */
 298                                 break;
 299                         case TRY_AGAIN:
 300                                 if (hp->rcode == SERVFAIL) {
 301                                         /* try next search element, if any */
 302                                         got_servfail++;
 303                                         break;
 304                                 }
 305                                 /* FALLTHROUGH */
 306                         default:
 307                                 /* anything else implies that we're done */
 308                                 done++;
 309                         }
 310
 311                         /* if we got here for some reason other than DNSRCH,
 312                          * we only wanted one iteration of the loop, so stop.
 313                          */
 314                         if ((statp->options & RES_DNSRCH) == 0U)
 315                                 done++;
 316                 }
 317         }
 318
 319         /*
 320          * If the query has not already been tried as is then try it
 321          * unless RES_NOTLDQUERY is set and there were no dots.
 322          */
 323         if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
 324             !(tried_as_is || root_on_list)) {
 325                 ret = res_nquerydomain(statp, name, NULL, class, type,
 326                                        answer, anslen);
 327                 if (ret > 0)
 328                         return (ret);
 329         }
 330
 331         /* if we got here, we didn't satisfy the search.
 332          * if we did an initial full query, return that query's H_ERRNO
 333          * (note that we wouldn't be here if that query had succeeded).
 334          * else if we ever got a nodata, send that back as the reason.
 335          * else send back meaningless H_ERRNO, that being the one from
 336          * the last DNSRCH we did.
 337          */
 338         if (saved_herrno != -1)
 339                 RES_SET_H_ERRNO(statp, saved_herrno);
 340         else if (got_nodata)
 341                 RES_SET_H_ERRNO(statp, NO_DATA);
 342         else if (got_servfail)
 343                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 344         return (-1);
 345 }
 346
 347 /*
 348  * Perform a call on res_query on the concatenation of name and domain,
 349  * removing a trailing dot from name if domain is NULL.
 350  */
 351 int
 352 res_nquerydomain(res_state statp,
 353             const char *name,
 354             const char *domain,
 355             int class, int type,        /* class and type of query */
 356             u_char *answer,             /* buffer to put answer */
 357             int anslen)         /* size of answer */
 358 {
 359         char nbuf[MAXDNAME];
 360         const char *longname = nbuf;
 361         int n, d;
 362
 363 #ifdef DEBUG
 364         if (statp->options & RES_DEBUG)
 365                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 366                        name, domain?domain:"<Nil>", class, type);
 367 #endif
 368         if (domain == NULL) {
 369                 /*
 370                  * Check for trailing '.';
 371                  * copy without '.' if present.
 372                  */
 373                 n = strlen(name);
 374                 if (n >= MAXDNAME) {
 375                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 376                         return (-1);
 377                 }
 378                 n--;
 379                 if (n >= 0 && name[n] == '.') {
 380                         strncpy(nbuf, name, n);
 381                         nbuf[n] = '\0';
 382                 } else
 383                         longname = name;
 384         } else {
 385                 n = strlen(name);
 386                 d = strlen(domain);
 387                 if (n + d + 1 >= MAXDNAME) {
 388                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 389                         return (-1);
 390                 }
 391                 sprintf(nbuf, "%s.%s", name, domain);
 392         }
 393         return (res_nquery(statp, longname, class, type, answer, anslen));
 394 }
 395
 396 const char *
 397 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 398         char *file, *cp1, *cp2;
 399         char buf[BUFSIZ];
 400         FILE *fp;
 401
 402         if (statp->options & RES_NOALIASES)
 403                 return (NULL);
 404         file = getenv("HOSTALIASES");
 405         if (file == NULL || (fp = fopen(file, "r")) == NULL)
 406                 return (NULL);
 407         setbuf(fp, NULL);
 408         buf[sizeof(buf) - 1] = '\0';
 409         while (fgets(buf, sizeof(buf), fp)) {
 410                 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
 411                         ;
 412                 if (!*cp1)
 413                         break;
 414                 *cp1 = '\0';
 415                 if (ns_samename(buf, name) == 1) {
 416                         while (isspace((unsigned char)*++cp1))
 417                                 ;
 418                         if (!*cp1)
 419                                 break;
 420                         for (cp2 = cp1 + 1; *cp2 &&
 421                              !isspace((unsigned char)*cp2); ++cp2)
 422                                 ;
 423                         *cp2 = '\0';
 424                         strncpy(dst, cp1, siz - 1);
 425                         dst[siz - 1] = '\0';
 426                         fclose(fp);
 427                         return (dst);
 428                 }
 429         }
 430         fclose(fp);
 431         return (NULL);
 432 }