res_query.c revision 1.11
1 /* $NetBSD: res_query.c,v 1.11 2008/06/21 23:37:53 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 1.11 2008/06/21 23:37:53 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 #ifndef DEBUG 112 #define DEBUG 113 #endif 114 115 #if PACKETSZ > 1024 116 #define MAXPACKET PACKETSZ 117 #else 118 #define MAXPACKET 1024 119 #endif 120 121 /*% 122 * Formulate a normal query, send, and await answer. 123 * Returned answer is placed in supplied buffer "answer". 124 * Perform preliminary check of answer, returning success only 125 * if no error is indicated and the answer count is nonzero. 126 * Return the size of the response on success, -1 on error. 127 * Error number is left in H_ERRNO. 128 * 129 * Caller must parse answer and determine whether it answers the question. 130 */ 131 int 132 res_nquery(res_state statp, 133 const char *name, /*%< domain name */ 134 int class, int type, /*%< class and type of query */ 135 u_char *answer, /*%< buffer to put answer */ 136 int anslen) /*%< size of answer buffer */ 137 { 138 u_char buf[MAXPACKET]; 139 HEADER *hp = (HEADER *)(void *)answer; 140 int n; 141 u_int oflags; 142 u_char *rdata; 143 144 oflags = statp->_flags; 145 146 again: 147 hp->rcode = NOERROR; /*%< default */ 148 #ifdef DEBUG 149 if (statp->options & RES_DEBUG) 150 printf(";; res_query(%s, %d, %d)\n", name, class, type); 151 #endif 152 153 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 154 buf, sizeof(buf)); 155 #ifdef RES_USE_EDNS0 156 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 157 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) { 158 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 159 rdata = &buf[n]; 160 if (n > 0 && (statp->options & RES_NSID) != 0U) { 161 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 162 NS_OPT_NSID, 0, NULL); 163 } 164 } 165 #endif 166 if (n <= 0) { 167 #ifdef DEBUG 168 if (statp->options & RES_DEBUG) 169 printf(";; res_query: mkquery failed\n"); 170 #endif 171 RES_SET_H_ERRNO(statp, NO_RECOVERY); 172 return (n); 173 } 174 175 n = res_nsend(statp, buf, n, answer, anslen); 176 if (n < 0) { 177 #ifdef RES_USE_EDNS0 178 /* if the query choked with EDNS0, retry without EDNS0 */ 179 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 180 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 181 statp->_flags |= RES_F_EDNS0ERR; 182 if (statp->options & RES_DEBUG) 183 printf(";; res_nquery: retry without EDNS0\n"); 184 goto again; 185 } 186 #endif 187 #ifdef DEBUG 188 if (statp->options & RES_DEBUG) 189 printf(";; res_query: send error\n"); 190 #endif 191 RES_SET_H_ERRNO(statp, TRY_AGAIN); 192 return (n); 193 } 194 195 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 196 #ifdef DEBUG 197 if (statp->options & RES_DEBUG) 198 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 199 p_rcode(hp->rcode), 200 ntohs(hp->ancount), 201 ntohs(hp->nscount), 202 ntohs(hp->arcount)); 203 #endif 204 switch (hp->rcode) { 205 case NXDOMAIN: 206 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 207 break; 208 case SERVFAIL: 209 RES_SET_H_ERRNO(statp, TRY_AGAIN); 210 break; 211 case NOERROR: 212 RES_SET_H_ERRNO(statp, NO_DATA); 213 break; 214 case FORMERR: 215 case NOTIMP: 216 case REFUSED: 217 default: 218 RES_SET_H_ERRNO(statp, NO_RECOVERY); 219 break; 220 } 221 return (-1); 222 } 223 return (n); 224 } 225 226 /*% 227 * Formulate a normal query, send, and retrieve answer in supplied buffer. 228 * Return the size of the response on success, -1 on error. 229 * If enabled, implement search rules until answer or unrecoverable failure 230 * is detected. Error code, if any, is left in H_ERRNO. 231 */ 232 int 233 res_nsearch(res_state statp, 234 const char *name, /*%< domain name */ 235 int class, int type, /*%< class and type of query */ 236 u_char *answer, /*%< buffer to put answer */ 237 int anslen) /*%< size of answer */ 238 { 239 const char *cp, * const *domain; 240 HEADER *hp = (HEADER *)(void *)answer; 241 char tmp[NS_MAXDNAME]; 242 u_int dots; 243 int trailing_dot, ret, saved_herrno; 244 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 245 int tried_as_is = 0; 246 int searched = 0; 247 248 errno = 0; 249 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 250 dots = 0; 251 for (cp = name; *cp != '\0'; cp++) 252 dots += (*cp == '.'); 253 trailing_dot = 0; 254 if (cp > name && *--cp == '.') 255 trailing_dot++; 256 257 /* If there aren't any dots, it could be a user-level alias. */ 258 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 259 return (res_nquery(statp, cp, class, type, answer, anslen)); 260 261 /* 262 * If there are enough dots in the name, let's just give it a 263 * try 'as is'. The threshold can be set with the "ndots" option. 264 * Also, query 'as is', if there is a trailing dot in the name. 265 */ 266 saved_herrno = -1; 267 if (dots >= statp->ndots || trailing_dot) { 268 ret = res_nquerydomain(statp, name, NULL, class, type, 269 answer, anslen); 270 if (ret > 0 || trailing_dot) 271 return (ret); 272 saved_herrno = statp->res_h_errno; 273 tried_as_is++; 274 } 275 276 /* 277 * We do at least one level of search if 278 * - there is no dot and RES_DEFNAME is set, or 279 * - there is at least one dot, there is no trailing dot, 280 * and RES_DNSRCH is set. 281 */ 282 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 283 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 284 int done = 0; 285 286 for (domain = (const char * const *)statp->dnsrch; 287 *domain && !done; 288 domain++) { 289 searched = 1; 290 291 if (domain[0][0] == '\0' || 292 (domain[0][0] == '.' && domain[0][1] == '\0')) 293 root_on_list++; 294 295 ret = res_nquerydomain(statp, name, *domain, 296 class, type, 297 answer, anslen); 298 if (ret > 0) 299 return (ret); 300 301 /* 302 * If no server present, give up. 303 * If name isn't found in this domain, 304 * keep trying higher domains in the search list 305 * (if that's enabled). 306 * On a NO_DATA error, keep trying, otherwise 307 * a wildcard entry of another type could keep us 308 * from finding this entry higher in the domain. 309 * If we get some other error (negative answer or 310 * server failure), then stop searching up, 311 * but try the input name below in case it's 312 * fully-qualified. 313 */ 314 if (errno == ECONNREFUSED) { 315 RES_SET_H_ERRNO(statp, TRY_AGAIN); 316 return (-1); 317 } 318 319 switch (statp->res_h_errno) { 320 case NO_DATA: 321 got_nodata++; 322 /* FALLTHROUGH */ 323 case HOST_NOT_FOUND: 324 /* keep trying */ 325 break; 326 case TRY_AGAIN: 327 if (hp->rcode == SERVFAIL) { 328 /* try next search element, if any */ 329 got_servfail++; 330 break; 331 } 332 /* FALLTHROUGH */ 333 default: 334 /* anything else implies that we're done */ 335 done++; 336 } 337 338 /* if we got here for some reason other than DNSRCH, 339 * we only wanted one iteration of the loop, so stop. 340 */ 341 if ((statp->options & RES_DNSRCH) == 0U) 342 done++; 343 } 344 } 345 346 /* 347 * If the query has not already been tried as is then try it 348 * unless RES_NOTLDQUERY is set and there were no dots. 349 */ 350 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 351 !(tried_as_is || root_on_list)) { 352 ret = res_nquerydomain(statp, name, NULL, class, type, 353 answer, anslen); 354 if (ret > 0) 355 return (ret); 356 } 357 358 /* if we got here, we didn't satisfy the search. 359 * if we did an initial full query, return that query's H_ERRNO 360 * (note that we wouldn't be here if that query had succeeded). 361 * else if we ever got a nodata, send that back as the reason. 362 * else send back meaningless H_ERRNO, that being the one from 363 * the last DNSRCH we did. 364 */ 365 if (saved_herrno != -1) 366 RES_SET_H_ERRNO(statp, saved_herrno); 367 else if (got_nodata) 368 RES_SET_H_ERRNO(statp, NO_DATA); 369 else if (got_servfail) 370 RES_SET_H_ERRNO(statp, TRY_AGAIN); 371 return (-1); 372 } 373 374 /*% 375 * Perform a call on res_query on the concatenation of name and domain, 376 * removing a trailing dot from name if domain is NULL. 377 */ 378 int 379 res_nquerydomain(res_state statp, 380 const char *name, 381 const char *domain, 382 int class, int type, /*%< class and type of query */ 383 u_char *answer, /*%< buffer to put answer */ 384 int anslen) /*%< size of answer */ 385 { 386 char nbuf[MAXDNAME]; 387 const char *longname = nbuf; 388 int n, d; 389 390 #ifdef DEBUG 391 if (statp->options & RES_DEBUG) 392 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 393 name, domain?domain:"<Nil>", class, type); 394 #endif 395 if (domain == NULL) { 396 /* 397 * Check for trailing '.'; 398 * copy without '.' if present. 399 */ 400 n = strlen(name); 401 if (n >= MAXDNAME) { 402 RES_SET_H_ERRNO(statp, NO_RECOVERY); 403 return (-1); 404 } 405 n--; 406 if (n >= 0 && name[n] == '.') { 407 strncpy(nbuf, name, (size_t)n); 408 nbuf[n] = '\0'; 409 } else 410 longname = name; 411 } else { 412 n = strlen(name); 413 d = strlen(domain); 414 if (n + d + 1 >= MAXDNAME) { 415 RES_SET_H_ERRNO(statp, NO_RECOVERY); 416 return (-1); 417 } 418 sprintf(nbuf, "%s.%s", name, domain); 419 } 420 return (res_nquery(statp, longname, class, type, answer, anslen)); 421 } 422 423 const char * 424 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 425 char *file, *cp1, *cp2; 426 char buf[BUFSIZ]; 427 FILE *fp; 428 429 if (statp->options & RES_NOALIASES) 430 return (NULL); 431 /* 432 * forbid hostaliases for setuid binary, due to possible security 433 * breach. 434 */ 435 if (issetugid()) 436 return (NULL); 437 file = getenv("HOSTALIASES"); 438 if (file == NULL || (fp = fopen(file, "r")) == NULL) 439 return (NULL); 440 setbuf(fp, NULL); 441 buf[sizeof(buf) - 1] = '\0'; 442 while (fgets(buf, sizeof(buf), fp)) { 443 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 444 ; 445 if (!*cp1) 446 break; 447 *cp1 = '\0'; 448 if (ns_samename(buf, name) == 1) { 449 while (isspace((unsigned char)*++cp1)) 450 ; 451 if (!*cp1) 452 break; 453 for (cp2 = cp1 + 1; *cp2 && 454 !isspace((unsigned char)*cp2); ++cp2) 455 ; 456 *cp2 = '\0'; 457 strncpy(dst, cp1, siz - 1); 458 dst[siz - 1] = '\0'; 459 fclose(fp); 460 return (dst); 461 } 462 } 463 fclose(fp); 464 return (NULL); 465 } 466 467 /*! \file */ 468
Indexes created Mon Sep 22 13:09:51 GMT 2025