res_query.c revision 1.18
1 /* $NetBSD: res_query.c,v 1.18 2024/08/24 22:37:41 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 /* 70 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 71 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 72 * 73 * Permission to use, copy, modify, and distribute this software for any 74 * purpose with or without fee is hereby granted, provided that the above 75 * copyright notice and this permission notice appear in all copies. 76 * 77 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 78 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 79 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 80 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 81 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 82 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 83 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 84 */ 85 86 #include <sys/cdefs.h> 87 #if defined(LIBC_SCCS) && !defined(lint) 88 #ifdef notdef 89 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 90 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp"; 91 #else 92 __RCSID("$NetBSD: res_query.c,v 1.18 2024/08/24 22:37:41 christos Exp $"); 93 #endif 94 #endif /* LIBC_SCCS and not lint */ 95 96 #include "port_before.h" 97 98 #include "namespace.h" 99 #include <sys/types.h> 100 #include <sys/param.h> 101 #include <netinet/in.h> 102 #include <arpa/inet.h> 103 #include <arpa/nameser.h> 104 #include <ctype.h> 105 #include <errno.h> 106 #include <netdb.h> 107 #include <resolv.h> 108 #include <stdio.h> 109 #include <stdlib.h> 110 #include <unistd.h> 111 #include <string.h> 112 #include "port_after.h" 113 114 #if 0 115 #ifdef __weak_alias 116 __weak_alias(res_nquery,_res_nquery) 117 __weak_alias(res_nsearch,_res_nsearch) 118 __weak_alias(res_nquerydomain,__res_nquerydomain) 119 __weak_alias(res_hostalias,__res_hostalias) 120 #endif 121 #endif 122 123 /* Options. Leave them on. */ 124 #ifndef DEBUG 125 #define DEBUG 126 #endif 127 128 #if PACKETSZ > 1024 129 #define MAXPACKET PACKETSZ 130 #else 131 #define MAXPACKET 1024 132 #endif 133 134 /*% 135 * Formulate a normal query, send, and await answer. 136 * Returned answer is placed in supplied buffer "answer". 137 * Perform preliminary check of answer, returning success only 138 * if no error is indicated and the answer count is nonzero. 139 * Return the size of the response on success, -1 on error. 140 * Error number is left in H_ERRNO. 141 * 142 * Caller must parse answer and determine whether it answers the question. 143 */ 144 int 145 res_nquery(res_state statp, 146 const char *name, /*%< domain name */ 147 int class, int type, /*%< class and type of query */ 148 u_char *answer, /*%< buffer to put answer */ 149 int anslen) /*%< size of answer buffer */ 150 { 151 u_char buf[MAXPACKET]; 152 HEADER *hp = (HEADER *)(void *)answer; 153 u_int oflags; 154 int n; 155 156 oflags = statp->_flags; 157 158 again: 159 hp->rcode = NOERROR; /*%< default */ 160 #ifdef DEBUG 161 if (statp->options & RES_DEBUG) 162 printf(";; res_query(%s, %d, %d)\n", name, class, type); 163 #endif 164 165 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 166 buf, (int)sizeof(buf)); 167 #ifdef RES_USE_EDNS0 168 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 169 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) { 170 n = res_nopt(statp, n, buf, (int)sizeof(buf), anslen); 171 if (n > 0 && (statp->options & RES_NSID) != 0U) { 172 n = res_nopt_rdata(statp, n, buf, (int)sizeof(buf), 173 buf + n, NS_OPT_NSID, 0, NULL); 174 } 175 } 176 #endif 177 if (n <= 0) { 178 #ifdef DEBUG 179 if (statp->options & RES_DEBUG) 180 printf(";; res_query: mkquery failed\n"); 181 #endif 182 RES_SET_H_ERRNO(statp, NO_RECOVERY); 183 return (n); 184 } 185 186 n = res_nsend(statp, buf, n, answer, anslen); 187 if (n < 0) { 188 #ifdef RES_USE_EDNS0 189 /* if the query choked with EDNS0, retry without EDNS0 */ 190 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 191 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 192 statp->_flags |= RES_F_EDNS0ERR; 193 if (statp->options & RES_DEBUG) 194 printf(";; res_nquery: retry without EDNS0\n"); 195 goto again; 196 } 197 #endif 198 #ifdef DEBUG 199 if (statp->options & RES_DEBUG) 200 printf(";; res_query: send error\n"); 201 #endif 202 RES_SET_H_ERRNO(statp, TRY_AGAIN); 203 return (n); 204 } 205 206 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 207 #ifdef DEBUG 208 if (statp->options & RES_DEBUG) 209 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 210 p_rcode(hp->rcode), 211 ntohs(hp->ancount), 212 ntohs(hp->nscount), 213 ntohs(hp->arcount)); 214 #endif 215 switch (hp->rcode) { 216 case NXDOMAIN: 217 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 218 break; 219 case SERVFAIL: 220 RES_SET_H_ERRNO(statp, TRY_AGAIN); 221 break; 222 case NOERROR: 223 RES_SET_H_ERRNO(statp, NO_DATA); 224 break; 225 case FORMERR: 226 case NOTIMP: 227 case REFUSED: 228 default: 229 RES_SET_H_ERRNO(statp, NO_RECOVERY); 230 break; 231 } 232 return (-1); 233 } 234 return (n); 235 } 236 237 /*% 238 * Formulate a normal query, send, and retrieve answer in supplied buffer. 239 * Return the size of the response on success, -1 on error. 240 * If enabled, implement search rules until answer or unrecoverable failure 241 * is detected. Error code, if any, is left in H_ERRNO. 242 */ 243 int 244 res_nsearch(res_state statp, 245 const char *name, /*%< domain name */ 246 int class, int type, /*%< class and type of query */ 247 u_char *answer, /*%< buffer to put answer */ 248 int anslen) /*%< size of answer */ 249 { 250 const char *cp, * const *domain; 251 HEADER *hp = (HEADER *)(void *)answer; 252 char tmp[NS_MAXDNAME]; 253 u_int dots; 254 int trailing_dot, ret, saved_herrno; 255 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 256 int tried_as_is = 0; 257 int searched = 0; 258 259 errno = 0; 260 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 261 dots = 0; 262 for (cp = name; *cp != '\0'; cp++) 263 dots += (*cp == '.'); 264 trailing_dot = 0; 265 if (cp > name && *--cp == '.') 266 trailing_dot++; 267 268 /* If there aren't any dots, it could be a user-level alias. */ 269 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 270 return (res_nquery(statp, cp, class, type, answer, anslen)); 271 272 /* 273 * If there are enough dots in the name, let's just give it a 274 * try 'as is'. The threshold can be set with the "ndots" option. 275 * Also, query 'as is', if there is a trailing dot in the name. 276 */ 277 saved_herrno = -1; 278 if (dots >= statp->ndots || trailing_dot) { 279 ret = res_nquerydomain(statp, name, NULL, class, type, 280 answer, anslen); 281 if (ret > 0 || trailing_dot) 282 return (ret); 283 saved_herrno = statp->res_h_errno; 284 tried_as_is++; 285 } 286 287 /* 288 * We do at least one level of search if 289 * - there is no dot and RES_DEFNAME is set, or 290 * - there is at least one dot, there is no trailing dot, 291 * and RES_DNSRCH is set. 292 */ 293 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 294 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 295 int done = 0; 296 297 for (domain = (const char * const *)statp->dnsrch; 298 *domain && !done; 299 domain++) { 300 searched = 1; 301 302 if (domain[0][0] == '\0' || 303 (domain[0][0] == '.' && domain[0][1] == '\0')) 304 root_on_list++; 305 306 ret = res_nquerydomain(statp, name, *domain, 307 class, type, 308 answer, anslen); 309 if (ret > 0) 310 return (ret); 311 312 /* 313 * If no server present, give up. 314 * If name isn't found in this domain, 315 * keep trying higher domains in the search list 316 * (if that's enabled). 317 * On a NO_DATA error, keep trying, otherwise 318 * a wildcard entry of another type could keep us 319 * from finding this entry higher in the domain. 320 * If we get some other error (negative answer or 321 * server failure), then stop searching up, 322 * but try the input name below in case it's 323 * fully-qualified. 324 */ 325 if (errno == ECONNREFUSED) { 326 RES_SET_H_ERRNO(statp, TRY_AGAIN); 327 return (-1); 328 } 329 330 switch (statp->res_h_errno) { 331 case NO_DATA: 332 got_nodata++; 333 /* FALLTHROUGH */ 334 case HOST_NOT_FOUND: 335 /* keep trying */ 336 break; 337 case TRY_AGAIN: 338 if (hp->rcode == SERVFAIL) { 339 /* try next search element, if any */ 340 got_servfail++; 341 break; 342 } 343 /* FALLTHROUGH */ 344 default: 345 /* anything else implies that we're done */ 346 done++; 347 } 348 349 /* if we got here for some reason other than DNSRCH, 350 * we only wanted one iteration of the loop, so stop. 351 */ 352 if ((statp->options & RES_DNSRCH) == 0U) 353 done++; 354 } 355 } 356 357 /* 358 * If the query has not already been tried as is then try it 359 * unless RES_NOTLDQUERY is set and there were no dots. 360 */ 361 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 362 !(tried_as_is || root_on_list)) { 363 ret = res_nquerydomain(statp, name, NULL, class, type, 364 answer, anslen); 365 if (ret > 0) 366 return (ret); 367 } 368 369 /* if we got here, we didn't satisfy the search. 370 * if we did an initial full query, return that query's H_ERRNO 371 * (note that we wouldn't be here if that query had succeeded). 372 * else if we ever got a nodata, send that back as the reason. 373 * else send back meaningless H_ERRNO, that being the one from 374 * the last DNSRCH we did. 375 */ 376 if (saved_herrno != -1) 377 RES_SET_H_ERRNO(statp, saved_herrno); 378 else if (got_nodata) 379 RES_SET_H_ERRNO(statp, NO_DATA); 380 else if (got_servfail) 381 RES_SET_H_ERRNO(statp, TRY_AGAIN); 382 return (-1); 383 } 384 385 /*% 386 * Perform a call on res_query on the concatenation of name and domain, 387 * removing a trailing dot from name if domain is NULL. 388 */ 389 int 390 res_nquerydomain(res_state statp, 391 const char *name, 392 const char *domain, 393 int class, int type, /*%< class and type of query */ 394 u_char *answer, /*%< buffer to put answer */ 395 int anslen) /*%< size of answer */ 396 { 397 char nbuf[MAXDNAME]; 398 const char *longname = nbuf; 399 size_t n; 400 401 #ifdef DEBUG 402 if (statp->options & RES_DEBUG) 403 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 404 name, domain?domain:"<Nil>", class, type); 405 #endif 406 if (domain == NULL) { 407 /* 408 * Check for trailing '.'; 409 * copy without '.' if present. 410 */ 411 n = strlen(name); 412 if (n >= MAXDNAME) { 413 RES_SET_H_ERRNO(statp, NO_RECOVERY); 414 return (-1); 415 } 416 if (n && name[--n] == '.') { 417 snprintf(nbuf, sizeof(nbuf), "%*s", (int)n, name); 418 } else 419 longname = name; 420 } else { 421 if ((size_t)snprintf(nbuf, sizeof(nbuf), "%s.%s", 422 name, domain) >= sizeof(nbuf)) { 423 RES_SET_H_ERRNO(statp, NO_RECOVERY); 424 return (-1); 425 } 426 } 427 return (res_nquery(statp, longname, class, type, answer, anslen)); 428 } 429 430 const char * 431 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 432 char *file, *cp1, *cp2; 433 char buf[BUFSIZ]; 434 FILE *fp; 435 436 if (statp->options & RES_NOALIASES) 437 return (NULL); 438 /* 439 * forbid hostaliases for setuid binary, due to possible security 440 * breach. 441 */ 442 if (issetugid()) 443 return (NULL); 444 file = getenv("HOSTALIASES"); 445 if (file == NULL || (fp = fopen(file, "re")) == NULL) 446 return (NULL); 447 buf[sizeof(buf) - 1] = '\0'; 448 while (fgets(buf, (int)sizeof(buf), fp)) { 449 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 450 ; 451 if (!*cp1) 452 break; 453 *cp1 = '\0'; 454 if (ns_samename(buf, name) == 1) { 455 while (isspace((unsigned char)*++cp1)) 456 ; 457 if (!*cp1) 458 break; 459 for (cp2 = cp1 + 1; *cp2 && 460 !isspace((unsigned char)*cp2); ++cp2) 461 ; 462 *cp2 = '\0'; 463 strncpy(dst, cp1, siz - 1); 464 dst[siz - 1] = '\0'; 465 fclose(fp); 466 return (dst); 467 } 468 } 469 fclose(fp); 470 return (NULL); 471 } 472 473 /*! \file */ 474
Indexes created Tue Sep 23 02:09:52 GMT 2025