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