1 /* $NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 /* 37 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 38 * 39 * Permission to use, copy, modify, and distribute this software for any 40 * purpose with or without fee is hereby granted, provided that the above 41 * copyright notice and this permission notice appear in all copies, and that 42 * the name of Digital Equipment Corporation not be used in advertising or 43 * publicity pertaining to distribution of the document or software without 44 * specific, written prior permission. 45 * 46 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 47 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 48 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 49 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 50 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 51 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 52 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 53 * SOFTWARE. 54 */ 55 56 /* 57 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 58 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 59 * 60 * Permission to use, copy, modify, and distribute this software for any 61 * purpose with or without fee is hereby granted, provided that the above 62 * copyright notice and this permission notice appear in all copies. 63 * 64 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 65 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 66 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 67 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 68 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 69 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 70 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 71 */ 72 73 #include <sys/cdefs.h> 74 #if defined(LIBC_SCCS) && !defined(lint) 75 #ifdef notdef 76 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 77 static const char rcsid[] = "Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp"; 78 #else 79 __RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $"); 80 #endif 81 #endif /* LIBC_SCCS and not lint */ 82 83 84 85 #include <sys/types.h> 86 #include <sys/param.h> 87 #include <netinet/in.h> 88 #include <arpa/inet.h> 89 #include "arpa_nameser.h" 90 #include <ctype.h> 91 #include <errno.h> 92 #include <netdb.h> 93 #ifdef ANDROID_CHANGES 94 #include "resolv_private.h" 95 #else 96 #include <resolv.h> 97 #endif 98 #include <stdio.h> 99 #include <stdlib.h> 100 #include <unistd.h> 101 #include <string.h> 102 103 #define DISABLE_HOST_ALIAS 1 104 105 /* Options. Leave them on. */ 106 #ifndef DEBUG 107 #define DEBUG 108 #endif 109 110 #if PACKETSZ > 1024 111 #define MAXPACKET PACKETSZ 112 #else 113 #define MAXPACKET 1024 114 #endif 115 116 /* 117 * Formulate a normal query, send, and await answer. 118 * Returned answer is placed in supplied buffer "answer". 119 * Perform preliminary check of answer, returning success only 120 * if no error is indicated and the answer count is nonzero. 121 * Return the size of the response on success, -1 on error. 122 * Error number is left in H_ERRNO. 123 * 124 * Caller must parse answer and determine whether it answers the question. 125 */ 126 int 127 res_nquery(res_state statp, 128 const char *name, /* domain name */ 129 int class, int type, /* class and type of query */ 130 u_char *answer, /* buffer to put answer */ 131 int anslen) /* size of answer buffer */ 132 { 133 u_char buf[MAXPACKET]; 134 HEADER *hp = (HEADER *)(void *)answer; 135 int n; 136 u_int oflags; 137 138 oflags = statp->_flags; 139 140 again: 141 hp->rcode = NOERROR; /* default */ 142 143 #ifdef DEBUG 144 if (statp->options & RES_DEBUG) 145 printf(";; res_query(%s, %d, %d)\n", name, class, type); 146 #endif 147 148 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 149 buf, sizeof(buf)); 150 #ifdef RES_USE_EDNS0 151 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 152 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U) 153 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 154 #endif 155 if (n <= 0) { 156 #ifdef DEBUG 157 if (statp->options & RES_DEBUG) 158 printf(";; res_query: mkquery failed\n"); 159 #endif 160 RES_SET_H_ERRNO(statp, NO_RECOVERY); 161 return (n); 162 } 163 n = res_nsend(statp, buf, n, answer, anslen); 164 if (n < 0) { 165 #ifdef RES_USE_EDNS0 166 /* if the query choked with EDNS0, retry without EDNS0 */ 167 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 168 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 169 statp->_flags |= RES_F_EDNS0ERR; 170 if (statp->options & RES_DEBUG) 171 printf(";; res_nquery: retry without EDNS0\n"); 172 goto again; 173 } 174 #endif 175 #ifdef DEBUG 176 if (statp->options & RES_DEBUG) 177 printf(";; res_query: send error\n"); 178 #endif 179 RES_SET_H_ERRNO(statp, TRY_AGAIN); 180 return (n); 181 } 182 183 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 184 #ifdef DEBUG 185 if (statp->options & RES_DEBUG) 186 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 187 p_rcode(hp->rcode), 188 ntohs(hp->ancount), 189 ntohs(hp->nscount), 190 ntohs(hp->arcount)); 191 #endif 192 switch (hp->rcode) { 193 case NXDOMAIN: 194 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 195 break; 196 case SERVFAIL: 197 RES_SET_H_ERRNO(statp, TRY_AGAIN); 198 break; 199 case NOERROR: 200 RES_SET_H_ERRNO(statp, NO_DATA); 201 break; 202 case FORMERR: 203 case NOTIMP: 204 case REFUSED: 205 default: 206 RES_SET_H_ERRNO(statp, NO_RECOVERY); 207 break; 208 } 209 return (-1); 210 } 211 return (n); 212 } 213 214 /* 215 * Formulate a normal query, send, and retrieve answer in supplied buffer. 216 * Return the size of the response on success, -1 on error. 217 * If enabled, implement search rules until answer or unrecoverable failure 218 * is detected. Error code, if any, is left in H_ERRNO. 219 */ 220 int 221 res_nsearch(res_state statp, 222 const char *name, /* domain name */ 223 int class, int type, /* class and type of query */ 224 u_char *answer, /* buffer to put answer */ 225 int anslen) /* size of answer */ 226 { 227 const char *cp, * const *domain; 228 HEADER *hp = (HEADER *)(void *)answer; 229 char tmp[NS_MAXDNAME]; 230 u_int dots; 231 int trailing_dot, ret, saved_herrno; 232 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 233 int tried_as_is = 0; 234 int searched = 0; 235 236 errno = 0; 237 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ 238 239 dots = 0; 240 for (cp = name; *cp != '\0'; cp++) 241 dots += (*cp == '.'); 242 trailing_dot = 0; 243 if (cp > name && *--cp == '.') 244 trailing_dot++; 245 246 /* If there aren't any dots, it could be a user-level alias. */ 247 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 248 return (res_nquery(statp, cp, class, type, answer, anslen)); 249 250 /* 251 * If there are enough dots in the name, let's just give it a 252 * try 'as is'. The threshold can be set with the "ndots" option. 253 * Also, query 'as is', if there is a trailing dot in the name. 254 */ 255 saved_herrno = -1; 256 if (dots >= statp->ndots || trailing_dot) { 257 ret = res_nquerydomain(statp, name, NULL, class, type, 258 answer, anslen); 259 if (ret > 0 || trailing_dot) 260 return (ret); 261 saved_herrno = statp->res_h_errno; 262 tried_as_is++; 263 } 264 265 /* 266 * We do at least one level of search if 267 * - there is no dot and RES_DEFNAME is set, or 268 * - there is at least one dot, there is no trailing dot, 269 * and RES_DNSRCH is set. 270 */ 271 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 272 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 273 int done = 0; 274 275 for (domain = (const char * const *)statp->dnsrch; 276 *domain && !done; 277 domain++) { 278 searched = 1; 279 280 if (domain[0][0] == '\0' || 281 (domain[0][0] == '.' && domain[0][1] == '\0')) 282 root_on_list++; 283 284 ret = res_nquerydomain(statp, name, *domain, 285 class, type, 286 answer, anslen); 287 if (ret > 0) 288 return (ret); 289 290 /* 291 * If no server present, give up. 292 * If name isn't found in this domain, 293 * keep trying higher domains in the search list 294 * (if that's enabled). 295 * On a NO_DATA error, keep trying, otherwise 296 * a wildcard entry of another type could keep us 297 * from finding this entry higher in the domain. 298 * If we get some other error (negative answer or 299 * server failure), then stop searching up, 300 * but try the input name below in case it's 301 * fully-qualified. 302 */ 303 if (errno == ECONNREFUSED) { 304 RES_SET_H_ERRNO(statp, TRY_AGAIN); 305 return (-1); 306 } 307 308 switch (statp->res_h_errno) { 309 case NO_DATA: 310 got_nodata++; 311 /* FALLTHROUGH */ 312 case HOST_NOT_FOUND: 313 /* keep trying */ 314 break; 315 case TRY_AGAIN: 316 if (hp->rcode == SERVFAIL) { 317 /* try next search element, if any */ 318 got_servfail++; 319 break; 320 } 321 /* FALLTHROUGH */ 322 default: 323 /* anything else implies that we're done */ 324 done++; 325 } 326 327 /* if we got here for some reason other than DNSRCH, 328 * we only wanted one iteration of the loop, so stop. 329 */ 330 if ((statp->options & RES_DNSRCH) == 0U) 331 done++; 332 } 333 } 334 335 /* 336 * If the query has not already been tried as is then try it 337 * unless RES_NOTLDQUERY is set and there were no dots. 338 */ 339 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 340 !(tried_as_is || root_on_list)) { 341 ret = res_nquerydomain(statp, name, NULL, class, type, 342 answer, anslen); 343 if (ret > 0) 344 return (ret); 345 } 346 347 /* if we got here, we didn't satisfy the search. 348 * if we did an initial full query, return that query's H_ERRNO 349 * (note that we wouldn't be here if that query had succeeded). 350 * else if we ever got a nodata, send that back as the reason. 351 * else send back meaningless H_ERRNO, that being the one from 352 * the last DNSRCH we did. 353 */ 354 if (saved_herrno != -1) 355 RES_SET_H_ERRNO(statp, saved_herrno); 356 else if (got_nodata) 357 RES_SET_H_ERRNO(statp, NO_DATA); 358 else if (got_servfail) 359 RES_SET_H_ERRNO(statp, TRY_AGAIN); 360 return (-1); 361 } 362 363 /* 364 * Perform a call on res_query on the concatenation of name and domain, 365 * removing a trailing dot from name if domain is NULL. 366 */ 367 int 368 res_nquerydomain(res_state statp, 369 const char *name, 370 const char *domain, 371 int class, int type, /* class and type of query */ 372 u_char *answer, /* buffer to put answer */ 373 int anslen) /* size of answer */ 374 { 375 char nbuf[MAXDNAME]; 376 const char *longname = nbuf; 377 int n, d; 378 379 #ifdef DEBUG 380 if (statp->options & RES_DEBUG) 381 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 382 name, domain?domain:"<Nil>", class, type); 383 #endif 384 if (domain == NULL) { 385 /* 386 * Check for trailing '.'; 387 * copy without '.' if present. 388 */ 389 n = strlen(name); 390 if (n >= MAXDNAME) { 391 RES_SET_H_ERRNO(statp, NO_RECOVERY); 392 return (-1); 393 } 394 n--; 395 if (n >= 0 && name[n] == '.') { 396 strncpy(nbuf, name, (size_t)n); 397 nbuf[n] = '\0'; 398 } else 399 longname = name; 400 } else { 401 n = strlen(name); 402 d = strlen(domain); 403 if (n + d + 1 >= MAXDNAME) { 404 RES_SET_H_ERRNO(statp, NO_RECOVERY); 405 return (-1); 406 } 407 sprintf(nbuf, "%s.%s", name, domain); 408 } 409 return (res_nquery(statp, longname, class, type, answer, anslen)); 410 } 411 412 const char * 413 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 414 return (NULL); 415 } 416
