res_query.c revision 1.10
1 /* $NetBSD: res_query.c,v 1.10 2008/06/21 20:41:48 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 1.8.672.2 2008/04/03 10:49:22 marka Exp"; 78 #else 79 __RCSID("$NetBSD: res_query.c,v 1.10 2008/06/21 20:41:48 christos Exp $"); 80 #endif 81 #endif /* LIBC_SCCS and not lint */ 82 83 #include "port_before.h" 84 85 #include "namespace.h" 86 #include <sys/types.h> 87 #include <sys/param.h> 88 #include <netinet/in.h> 89 #include <arpa/inet.h> 90 #include <arpa/nameser.h> 91 #include <ctype.h> 92 #include <errno.h> 93 #include <netdb.h> 94 #include <resolv.h> 95 #include <stdio.h> 96 #include <stdlib.h> 97 #include <unistd.h> 98 #include <string.h> 99 #include "port_after.h" 100 101 #if 0 102 #ifdef __weak_alias 103 __weak_alias(res_nquery,_res_nquery) 104 __weak_alias(res_nsearch,_res_nsearch) 105 __weak_alias(res_nquerydomain,__res_nquerydomain) 106 __weak_alias(res_hostalias,__res_hostalias) 107 #endif 108 #endif 109 110 /* Options. Leave them on. */ 111 #define DEBUG 112 113 #if PACKETSZ > 1024 114 #define MAXPACKET PACKETSZ 115 #else 116 #define MAXPACKET 1024 117 #endif 118 119 /*% 120 * Formulate a normal query, send, and await answer. 121 * Returned answer is placed in supplied buffer "answer". 122 * Perform preliminary check of answer, returning success only 123 * if no error is indicated and the answer count is nonzero. 124 * Return the size of the response on success, -1 on error. 125 * Error number is left in H_ERRNO. 126 * 127 * Caller must parse answer and determine whether it answers the question. 128 */ 129 int 130 res_nquery(res_state statp, 131 const char *name, /*%< domain name */ 132 int class, int type, /*%< class and type of query */ 133 u_char *answer, /*%< buffer to put answer */ 134 int anslen) /*%< size of answer buffer */ 135 { 136 u_char buf[MAXPACKET]; 137 HEADER *hp = (HEADER *)(void *)answer; 138 int n; 139 u_int oflags; 140 u_char *rdata; 141 142 oflags = statp->_flags; 143 144 again: 145 hp->rcode = NOERROR; /*%< default */ 146 #ifdef DEBUG 147 if (statp->options & RES_DEBUG) 148 printf(";; res_query(%s, %d, %d)\n", name, class, type); 149 #endif 150 151 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 152 buf, sizeof(buf)); 153 #ifdef RES_USE_EDNS0 154 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 155 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) { 156 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 157 rdata = &buf[n]; 158 if (n > 0 && (statp->options & RES_NSID) != 0U) { 159 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 160 NS_OPT_NSID, 0, NULL); 161 } 162 } 163 #endif 164 if (n <= 0) { 165 #ifdef DEBUG 166 if (statp->options & RES_DEBUG) 167 printf(";; res_query: mkquery failed\n"); 168 #endif 169 RES_SET_H_ERRNO(statp, NO_RECOVERY); 170 return (n); 171 } 172 173 n = res_nsend(statp, buf, n, answer, anslen); 174 if (n < 0) { 175 #ifdef RES_USE_EDNS0 176 /* if the query choked with EDNS0, retry without EDNS0 */ 177 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 178 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 179 statp->_flags |= RES_F_EDNS0ERR; 180 if (statp->options & RES_DEBUG) 181 printf(";; res_nquery: retry without EDNS0\n"); 182 goto again; 183 } 184 #endif 185 #ifdef DEBUG 186 if (statp->options & RES_DEBUG) 187 printf(";; res_query: send error\n"); 188 #endif 189 RES_SET_H_ERRNO(statp, TRY_AGAIN); 190 return (n); 191 } 192 193 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 194 #ifdef DEBUG 195 if (statp->options & RES_DEBUG) 196 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 197 p_rcode(hp->rcode), 198 ntohs(hp->ancount), 199 ntohs(hp->nscount), 200 ntohs(hp->arcount)); 201 #endif 202 switch (hp->rcode) { 203 case NXDOMAIN: 204 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 205 break; 206 case SERVFAIL: 207 RES_SET_H_ERRNO(statp, TRY_AGAIN); 208 break; 209 case NOERROR: 210 RES_SET_H_ERRNO(statp, NO_DATA); 211 break; 212 case FORMERR: 213 case NOTIMP: 214 case REFUSED: 215 default: 216 RES_SET_H_ERRNO(statp, NO_RECOVERY); 217 break; 218 } 219 return (-1); 220 } 221 return (n); 222 } 223 224 /*% 225 * Formulate a normal query, send, and retrieve answer in supplied buffer. 226 * Return the size of the response on success, -1 on error. 227 * If enabled, implement search rules until answer or unrecoverable failure 228 * is detected. Error code, if any, is left in H_ERRNO. 229 */ 230 int 231 res_nsearch(res_state statp, 232 const char *name, /*%< domain name */ 233 int class, int type, /*%< class and type of query */ 234 u_char *answer, /*%< buffer to put answer */ 235 int anslen) /*%< size of answer */ 236 { 237 const char *cp, * const *domain; 238 HEADER *hp = (HEADER *)(void *)answer; 239 char tmp[NS_MAXDNAME]; 240 u_int dots; 241 int trailing_dot, ret, saved_herrno; 242 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 243 int tried_as_is = 0; 244 int searched = 0; 245 246 errno = 0; 247 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 248 dots = 0; 249 for (cp = name; *cp != '\0'; cp++) 250 dots += (*cp == '.'); 251 trailing_dot = 0; 252 if (cp > name && *--cp == '.') 253 trailing_dot++; 254 255 /* If there aren't any dots, it could be a user-level alias. */ 256 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 257 return (res_nquery(statp, cp, class, type, answer, anslen)); 258 259 /* 260 * If there are enough dots in the name, let's just give it a 261 * try 'as is'. The threshold can be set with the "ndots" option. 262 * Also, query 'as is', if there is a trailing dot in the name. 263 */ 264 saved_herrno = -1; 265 if (dots >= statp->ndots || trailing_dot) { 266 ret = res_nquerydomain(statp, name, NULL, class, type, 267 answer, anslen); 268 if (ret > 0 || trailing_dot) 269 return (ret); 270 saved_herrno = statp->res_h_errno; 271 tried_as_is++; 272 } 273 274 /* 275 * We do at least one level of search if 276 * - there is no dot and RES_DEFNAME is set, or 277 * - there is at least one dot, there is no trailing dot, 278 * and RES_DNSRCH is set. 279 */ 280 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 281 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 282 int done = 0; 283 284 for (domain = (const char * const *)statp->dnsrch; 285 *domain && !done; 286 domain++) { 287 searched = 1; 288 289 if (domain[0][0] == '\0' || 290 (domain[0][0] == '.' && domain[0][1] == '\0')) 291 root_on_list++; 292 293 ret = res_nquerydomain(statp, name, *domain, 294 class, type, 295 answer, anslen); 296 if (ret > 0) 297 return (ret); 298 299 /* 300 * If no server present, give up. 301 * If name isn't found in this domain, 302 * keep trying higher domains in the search list 303 * (if that's enabled). 304 * On a NO_DATA error, keep trying, otherwise 305 * a wildcard entry of another type could keep us 306 * from finding this entry higher in the domain. 307 * If we get some other error (negative answer or 308 * server failure), then stop searching up, 309 * but try the input name below in case it's 310 * fully-qualified. 311 */ 312 if (errno == ECONNREFUSED) { 313 RES_SET_H_ERRNO(statp, TRY_AGAIN); 314 return (-1); 315 } 316 317 switch (statp->res_h_errno) { 318 case NO_DATA: 319 got_nodata++; 320 /* FALLTHROUGH */ 321 case HOST_NOT_FOUND: 322 /* keep trying */ 323 break; 324 case TRY_AGAIN: 325 if (hp->rcode == SERVFAIL) { 326 /* try next search element, if any */ 327 got_servfail++; 328 break; 329 } 330 /* FALLTHROUGH */ 331 default: 332 /* anything else implies that we're done */ 333 done++; 334 } 335 336 /* if we got here for some reason other than DNSRCH, 337 * we only wanted one iteration of the loop, so stop. 338 */ 339 if ((statp->options & RES_DNSRCH) == 0U) 340 done++; 341 } 342 } 343 344 /* 345 * If the query has not already been tried as is then try it 346 * unless RES_NOTLDQUERY is set and there were no dots. 347 */ 348 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 349 !(tried_as_is || root_on_list)) { 350 ret = res_nquerydomain(statp, name, NULL, class, type, 351 answer, anslen); 352 if (ret > 0) 353 return (ret); 354 } 355 356 /* if we got here, we didn't satisfy the search. 357 * if we did an initial full query, return that query's H_ERRNO 358 * (note that we wouldn't be here if that query had succeeded). 359 * else if we ever got a nodata, send that back as the reason. 360 * else send back meaningless H_ERRNO, that being the one from 361 * the last DNSRCH we did. 362 */ 363 if (saved_herrno != -1) 364 RES_SET_H_ERRNO(statp, saved_herrno); 365 else if (got_nodata) 366 RES_SET_H_ERRNO(statp, NO_DATA); 367 else if (got_servfail) 368 RES_SET_H_ERRNO(statp, TRY_AGAIN); 369 return (-1); 370 } 371 372 /*% 373 * Perform a call on res_query on the concatenation of name and domain, 374 * removing a trailing dot from name if domain is NULL. 375 */ 376 int 377 res_nquerydomain(res_state statp, 378 const char *name, 379 const char *domain, 380 int class, int type, /*%< class and type of query */ 381 u_char *answer, /*%< buffer to put answer */ 382 int anslen) /*%< size of answer */ 383 { 384 char nbuf[MAXDNAME]; 385 const char *longname = nbuf; 386 int n, d; 387 388 #ifdef DEBUG 389 if (statp->options & RES_DEBUG) 390 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 391 name, domain?domain:"<Nil>", class, type); 392 #endif 393 if (domain == NULL) { 394 /* 395 * Check for trailing '.'; 396 * copy without '.' if present. 397 */ 398 n = strlen(name); 399 if (n >= MAXDNAME) { 400 RES_SET_H_ERRNO(statp, NO_RECOVERY); 401 return (-1); 402 } 403 n--; 404 if (n >= 0 && name[n] == '.') { 405 strncpy(nbuf, name, (size_t)n); 406 nbuf[n] = '\0'; 407 } else 408 longname = name; 409 } else { 410 n = strlen(name); 411 d = strlen(domain); 412 if (n + d + 1 >= MAXDNAME) { 413 RES_SET_H_ERRNO(statp, NO_RECOVERY); 414 return (-1); 415 } 416 sprintf(nbuf, "%s.%s", name, domain); 417 } 418 return (res_nquery(statp, longname, class, type, answer, anslen)); 419 } 420 421 const char * 422 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 423 char *file, *cp1, *cp2; 424 char buf[BUFSIZ]; 425 FILE *fp; 426 427 if (statp->options & RES_NOALIASES) 428 return (NULL); 429 /* 430 * forbid hostaliases for setuid binary, due to possible security 431 * breach. 432 */ 433 if (issetugid()) 434 return (NULL); 435 file = getenv("HOSTALIASES"); 436 if (file == NULL || (fp = fopen(file, "r")) == NULL) 437 return (NULL); 438 setbuf(fp, NULL); 439 buf[sizeof(buf) - 1] = '\0'; 440 while (fgets(buf, sizeof(buf), fp)) { 441 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 442 ; 443 if (!*cp1) 444 break; 445 *cp1 = '\0'; 446 if (ns_samename(buf, name) == 1) { 447 while (isspace((unsigned char)*++cp1)) 448 ; 449 if (!*cp1) 450 break; 451 for (cp2 = cp1 + 1; *cp2 && 452 !isspace((unsigned char)*cp2); ++cp2) 453 ; 454 *cp2 = '\0'; 455 strncpy(dst, cp1, siz - 1); 456 dst[siz - 1] = '\0'; 457 fclose(fp); 458 return (dst); 459 } 460 } 461 fclose(fp); 462 return (NULL); 463 } 464 465 /*! \file */ 466
Indexes created Mon Sep 22 13:09:51 GMT 2025