src/kits/network/netresolv/resolv/res_query.c

   1 /*      $NetBSD: res_query.c,v 1.16 2015/02/24 17:56:20 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. Neither the name of the University nor the names of its contributors
  33  *    may be used to endorse or promote products derived from this software
  34  *    without specific prior written permission.
  35  *
  36  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  37  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  38  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  39  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  40  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  41  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  42  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  43  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  44  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  45  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  46  * SUCH DAMAGE.
  47  */
  48
  49 /*
  50  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
  51  *
  52  * Permission to use, copy, modify, and distribute this software for any
  53  * purpose with or without fee is hereby granted, provided that the above
  54  * copyright notice and this permission notice appear in all copies, and that
  55  * the name of Digital Equipment Corporation not be used in advertising or
  56  * publicity pertaining to distribution of the document or software without
  57  * specific, written prior permission.
  58  *
  59  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
  60  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
  61  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
  62  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  63  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
  64  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
  65  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
  66  * SOFTWARE.
  67  */
  68
  69 #if defined(LIBC_SCCS) && !defined(lint)
  70 static const char sccsid[] = "@(#)res_query.c   8.1 (Berkeley) 6/4/93";
  71 static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $";
  72 #endif /* LIBC_SCCS and not lint */
  73
  74 #include "port_before.h"
  75 #include <sys/types.h>
  76 #include <sys/param.h>
  77 #include <netinet/in.h>
  78 #include <arpa/inet.h>
  79 #include <arpa/nameser.h>
  80 #include <ctype.h>
  81 #include <errno.h>
  82 #include <netdb.h>
  83 #include <resolv.h>
  84 #include <stdio.h>
  85 #include <stdlib.h>
  86 #include <string.h>
  87 #include "port_after.h"
  88
  89 /* Options.  Leave them on. */
  90 //#define DEBUG
  91
  92 #if PACKETSZ > 1024
  93 #define MAXPACKET       PACKETSZ
  94 #else
  95 #define MAXPACKET       1024
  96 #endif
  97
  98 /*%
  99  * Formulate a normal query, send, and await answer.
 100  * Returned answer is placed in supplied buffer "answer".
 101  * Perform preliminary check of answer, returning success only
 102  * if no error is indicated and the answer count is nonzero.
 103  * Return the size of the response on success, -1 on error.
 104  * Error number is left in H_ERRNO.
 105  *
 106  * Caller must parse answer and determine whether it answers the question.
 107  */
 108 int
 109 res_nquery(res_state statp,
 110            const char *name,    /*%< domain name */
 111            int class, int type, /*%< class and type of query */
 112            u_char *answer,      /*%< buffer to put answer */
 113            int anslen)          /*%< size of answer buffer */
 114 {
 115         u_char buf[MAXPACKET];
 116         HEADER *hp = (HEADER *)(void *)answer;
 117         u_int oflags;
 118         u_char *rdata;
 119         int n;
 120
 121         oflags = statp->_flags;
 122
 123 again:
 124         hp->rcode = NOERROR;    /*%< default */
 125 #ifdef DEBUG
 126         if (statp->options & RES_DEBUG)
 127                 printf(";; res_query(%s, %d, %d)\n", name, class, type);
 128 #endif
 129
 130         n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
 131                          buf, sizeof(buf));
 132 #ifdef RES_USE_EDNS0
 133         if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
 134             (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) {
 135                 n = res_nopt(statp, n, buf, sizeof(buf), anslen);
 136                 if (n > 0 && (statp->options & RES_NSID) != 0U) {
 137                         rdata = &buf[n];
 138                         n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
 139                                            NS_OPT_NSID, 0, NULL);
 140                 }
 141         }
 142 #endif
 143         if (n <= 0) {
 144 #ifdef DEBUG
 145                 if (statp->options & RES_DEBUG)
 146                         printf(";; res_query: mkquery failed\n");
 147 #endif
 148                 RES_SET_H_ERRNO(statp, NO_RECOVERY);
 149                 return (n);
 150         }
 151
 152         n = res_nsend(statp, buf, n, answer, anslen);
 153         if (n < 0) {
 154 #ifdef RES_USE_EDNS0
 155                 /* if the query choked with EDNS0, retry without EDNS0 */
 156                 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
 157                     ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
 158                         statp->_flags |= RES_F_EDNS0ERR;
 159                         if (statp->options & RES_DEBUG)
 160                                 printf(";; res_nquery: retry without EDNS0\n");
 161                         goto again;
 162                 }
 163 #endif
 164 #ifdef DEBUG
 165                 if (statp->options & RES_DEBUG)
 166                         printf(";; res_query: send error\n");
 167 #endif
 168                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 169                 return (n);
 170         }
 171
 172         if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
 173 #ifdef DEBUG
 174                 if (statp->options & RES_DEBUG)
 175                         printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
 176                                p_rcode(hp->rcode),
 177                                ntohs(hp->ancount),
 178                                ntohs(hp->nscount),
 179                                ntohs(hp->arcount));
 180 #endif
 181                 switch (hp->rcode) {
 182                 case NXDOMAIN:
 183                         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
 184                         break;
 185                 case SERVFAIL:
 186                         RES_SET_H_ERRNO(statp, TRY_AGAIN);
 187                         break;
 188                 case NOERROR:
 189                         RES_SET_H_ERRNO(statp, NO_DATA);
 190                         break;
 191                 case FORMERR:
 192                 case NOTIMP:
 193                 case REFUSED:
 194                 default:
 195                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 196                         break;
 197                 }
 198                 return (-1);
 199         }
 200         return (n);
 201 }
 202
 203 /*%
 204  * Formulate a normal query, send, and retrieve answer in supplied buffer.
 205  * Return the size of the response on success, -1 on error.
 206  * If enabled, implement search rules until answer or unrecoverable failure
 207  * is detected.  Error code, if any, is left in H_ERRNO.
 208  */
 209 int
 210 res_nsearch(res_state statp,
 211             const char *name,   /*%< domain name */
 212             int class, int type,        /*%< class and type of query */
 213             u_char *answer,     /*%< buffer to put answer */
 214             int anslen)         /*%< size of answer */
 215 {
 216         const char *cp, * const *domain;
 217         HEADER *hp = (HEADER *)(void *)answer;
 218         char tmp[NS_MAXDNAME];
 219         u_int dots;
 220         int trailing_dot, ret, saved_herrno;
 221         int got_nodata = 0, got_servfail = 0, root_on_list = 0;
 222         int tried_as_is = 0;
 223         int searched = 0;
 224
 225         errno = 0;
 226         RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /*%< True if we never query. */
 227         dots = 0;
 228         for (cp = name; *cp != '\0'; cp++)
 229                 dots += (*cp == '.');
 230         trailing_dot = 0;
 231         if (cp > name && *--cp == '.')
 232                 trailing_dot++;
 233
 234         /* If there aren't any dots, it could be a user-level alias. */
 235         if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
 236                 return (res_nquery(statp, cp, class, type, answer, anslen));
 237
 238         /*
 239          * If there are enough dots in the name, let's just give it a
 240          * try 'as is'. The threshold can be set with the "ndots" option.
 241          * Also, query 'as is', if there is a trailing dot in the name.
 242          */
 243         saved_herrno = -1;
 244         if (dots >= statp->ndots || trailing_dot) {
 245                 ret = res_nquerydomain(statp, name, NULL, class, type,
 246                                          answer, anslen);
 247                 if (ret > 0 || trailing_dot)
 248                         return (ret);
 249                 saved_herrno = statp->res_h_errno;
 250                 tried_as_is++;
 251         }
 252
 253         /*
 254          * We do at least one level of search if
 255          *      - there is no dot and RES_DEFNAME is set, or
 256          *      - there is at least one dot, there is no trailing dot,
 257          *        and RES_DNSRCH is set.
 258          */
 259         if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
 260             (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
 261                 int done = 0;
 262
 263                 for (domain = (const char * const *)statp->dnsrch;
 264                      *domain && !done;
 265                      domain++) {
 266                         searched = 1;
 267
 268                         if (domain[0][0] == '\0' ||
 269                             (domain[0][0] == '.' && domain[0][1] == '\0'))
 270                                 root_on_list++;
 271
 272                         ret = res_nquerydomain(statp, name, *domain,
 273                                                class, type,
 274                                                answer, anslen);
 275                         if (ret > 0)
 276                                 return (ret);
 277
 278                         /*
 279                          * If no server present, give up.
 280                          * If name isn't found in this domain,
 281                          * keep trying higher domains in the search list
 282                          * (if that's enabled).
 283                          * On a NO_DATA error, keep trying, otherwise
 284                          * a wildcard entry of another type could keep us
 285                          * from finding this entry higher in the domain.
 286                          * If we get some other error (negative answer or
 287                          * server failure), then stop searching up,
 288                          * but try the input name below in case it's
 289                          * fully-qualified.
 290                          */
 291                         if (errno == ECONNREFUSED) {
 292                                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 293                                 return (-1);
 294                         }
 295
 296                         switch (statp->res_h_errno) {
 297                         case NO_DATA:
 298                                 got_nodata++;
 299                                 /* FALLTHROUGH */
 300                         case HOST_NOT_FOUND:
 301                                 /* keep trying */
 302                                 break;
 303                         case TRY_AGAIN:
 304                                 if (hp->rcode == SERVFAIL) {
 305                                         /* try next search element, if any */
 306                                         got_servfail++;
 307                                         break;
 308                                 }
 309                                 /* FALLTHROUGH */
 310                         default:
 311                                 /* anything else implies that we're done */
 312                                 done++;
 313                         }
 314
 315                         /* if we got here for some reason other than DNSRCH,
 316                          * we only wanted one iteration of the loop, so stop.
 317                          */
 318                         if ((statp->options & RES_DNSRCH) == 0U)
 319                                 done++;
 320                 }
 321         }
 322
 323         /*
 324          * If the query has not already been tried as is then try it
 325          * unless RES_NOTLDQUERY is set and there were no dots.
 326          */
 327         if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
 328             !(tried_as_is || root_on_list)) {
 329                 ret = res_nquerydomain(statp, name, NULL, class, type,
 330                                        answer, anslen);
 331                 if (ret > 0)
 332                         return (ret);
 333         }
 334
 335         /* if we got here, we didn't satisfy the search.
 336          * if we did an initial full query, return that query's H_ERRNO
 337          * (note that we wouldn't be here if that query had succeeded).
 338          * else if we ever got a nodata, send that back as the reason.
 339          * else send back meaningless H_ERRNO, that being the one from
 340          * the last DNSRCH we did.
 341          */
 342         if (saved_herrno != -1)
 343                 RES_SET_H_ERRNO(statp, saved_herrno);
 344         else if (got_nodata)
 345                 RES_SET_H_ERRNO(statp, NO_DATA);
 346         else if (got_servfail)
 347                 RES_SET_H_ERRNO(statp, TRY_AGAIN);
 348         return (-1);
 349 }
 350
 351 /*%
 352  * Perform a call on res_query on the concatenation of name and domain,
 353  * removing a trailing dot from name if domain is NULL.
 354  */
 355 int
 356 res_nquerydomain(res_state statp,
 357             const char *name,
 358             const char *domain,
 359             int class, int type,        /*%< class and type of query */
 360             u_char *answer,             /*%< buffer to put answer */
 361             int anslen)         /*%< size of answer */
 362 {
 363         char nbuf[MAXDNAME];
 364         const char *longname = nbuf;
 365         size_t n, d;
 366
 367 #ifdef DEBUG
 368         if (statp->options & RES_DEBUG)
 369                 printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
 370                        name, domain?domain:"<Nil>", class, type);
 371 #endif
 372         if (domain == NULL) {
 373                 /*
 374                  * Check for trailing '.';
 375                  * copy without '.' if present.
 376                  */
 377                 n = strlen(name);
 378                 if (n >= MAXDNAME) {
 379                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 380                         return (-1);
 381                 }
 382                 if (n && name[--n] == '.') {
 383                         strncpy(nbuf, name, n);
 384                         nbuf[n] = '\0';
 385                 } else
 386                         longname = name;
 387         } else {
 388                 n = strlen(name);
 389                 d = strlen(domain);
 390                 if (n + d + 1 >= MAXDNAME) {
 391                         RES_SET_H_ERRNO(statp, NO_RECOVERY);
 392                         return (-1);
 393                 }
 394                 sprintf(nbuf, "%s.%s", name, domain);
 395         }
 396         return (res_nquery(statp, longname, class, type, answer, anslen));
 397 }
 398
 399 const char *
 400 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
 401         char *file, *cp1, *cp2;
 402         char buf[BUFSIZ];
 403         FILE *fp;
 404
 405         if (statp->options & RES_NOALIASES)
 406                 return (NULL);
 407
 408         file = getenv("HOSTALIASES");
 409         if (file == NULL || (fp = fopen(file, "re")) == NULL)
 410                 return (NULL);
 411         buf[sizeof(buf) - 1] = '\0';
 412         while (fgets(buf, (int)sizeof(buf), fp)) {
 413                 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
 414                         ;
 415                 if (!*cp1)
 416                         break;
 417                 *cp1 = '\0';
 418                 if (ns_samename(buf, name) == 1) {
 419                         while (isspace((unsigned char)*++cp1))
 420                                 ;
 421                         if (!*cp1)
 422                                 break;
 423                         for (cp2 = cp1 + 1; *cp2 &&
 424                              !isspace((unsigned char)*cp2); ++cp2)
 425                                 ;
 426                         *cp2 = '\0';
 427                         strncpy(dst, cp1, siz - 1);
 428                         dst[siz - 1] = '\0';
 429                         fclose(fp);
 430                         return (dst);
 431                 }
 432         }
 433         fclose(fp);
 434         return (NULL);
 435 }
 436
 437 /*! \file */