res_query.c revision 1.7
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 #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; 142 143 oflags = statp->_flags; 144 145 again: 146 hp->rcode = NOERROR; /* default */ 147 148 #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)) != 0U) 158 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 159 #endif 160 if (n <= 0) { 161 #ifdef DEBUG 162 if (statp->options & RES_DEBUG) 163 printf(";; res_query: mkquery failed\n"); 164 #endif 165 RES_SET_H_ERRNO(statp, NO_RECOVERY); 166 return (n); 167 } 168 n = res_nsend(statp, buf, n, answer, anslen); 169 if (n < 0) { 170 #ifdef RES_USE_EDNS0 171 /* if the query choked with EDNS0, retry without EDNS0 */ 172 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 173 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 174 statp->_flags |= RES_F_EDNS0ERR; 175 if (statp->options & RES_DEBUG) 176 printf(";; res_nquery: retry without EDNS0\n"); 177 goto again; 178 } 179 #endif 180 #ifdef DEBUG 181 if (statp->options & RES_DEBUG) 182 printf(";; res_query: send error\n"); 183 #endif 184 RES_SET_H_ERRNO(statp, TRY_AGAIN); 185 return (n); 186 } 187 188 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 189 #ifdef DEBUG 190 if (statp->options & RES_DEBUG) 191 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 192 p_rcode(hp->rcode), 193 ntohs(hp->ancount), 194 ntohs(hp->nscount), 195 ntohs(hp->arcount)); 196 #endif 197 switch (hp->rcode) { 198 case NXDOMAIN: 199 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 200 break; 201 case SERVFAIL: 202 RES_SET_H_ERRNO(statp, TRY_AGAIN); 203 break; 204 case NOERROR: 205 RES_SET_H_ERRNO(statp, NO_DATA); 206 break; 207 case FORMERR: 208 case NOTIMP: 209 case REFUSED: 210 default: 211 RES_SET_H_ERRNO(statp, NO_RECOVERY); 212 break; 213 } 214 return (-1); 215 } 216 return (n); 217 } 218 219 /* 220 * Formulate a normal query, send, and retrieve answer in supplied buffer. 221 * Return the size of the response on success, -1 on error. 222 * If enabled, implement search rules until answer or unrecoverable failure 223 * is detected. Error code, if any, is left in H_ERRNO. 224 */ 225 int 226 res_nsearch(res_state statp, 227 const char *name, /* domain name */ 228 int class, int type, /* class and type of query */ 229 u_char *answer, /* buffer to put answer */ 230 int anslen) /* size of answer */ 231 { 232 const char *cp, * const *domain; 233 HEADER *hp = (HEADER *)(void *)answer; 234 char tmp[NS_MAXDNAME]; 235 u_int dots; 236 int trailing_dot, ret, saved_herrno; 237 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 238 int tried_as_is = 0; 239 int searched = 0; 240 241 errno = 0; 242 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ 243 244 dots = 0; 245 for (cp = name; *cp != '\0'; cp++) 246 dots += (*cp == '.'); 247 trailing_dot = 0; 248 if (cp > name && *--cp == '.') 249 trailing_dot++; 250 251 /* If there aren't any dots, it could be a user-level alias. */ 252 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 253 return (res_nquery(statp, cp, class, type, answer, anslen)); 254 255 /* 256 * If there are enough dots in the name, let's just give it a 257 * try 'as is'. The threshold can be set with the "ndots" option. 258 * Also, query 'as is', if there is a trailing dot in the name. 259 */ 260 saved_herrno = -1; 261 if (dots >= statp->ndots || trailing_dot) { 262 ret = res_nquerydomain(statp, name, NULL, class, type, 263 answer, anslen); 264 if (ret > 0 || trailing_dot) 265 return (ret); 266 saved_herrno = statp->res_h_errno; 267 tried_as_is++; 268 } 269 270 /* 271 * We do at least one level of search if 272 * - there is no dot and RES_DEFNAME is set, or 273 * - there is at least one dot, there is no trailing dot, 274 * and RES_DNSRCH is set. 275 */ 276 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 277 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 278 int done = 0; 279 280 for (domain = (const char * const *)statp->dnsrch; 281 *domain && !done; 282 domain++) { 283 searched = 1; 284 285 if (domain[0][0] == '\0' || 286 (domain[0][0] == '.' && domain[0][1] == '\0')) 287 root_on_list++; 288 289 ret = res_nquerydomain(statp, name, *domain, 290 class, type, 291 answer, anslen); 292 if (ret > 0) 293 return (ret); 294 295 /* 296 * If no server present, give up. 297 * If name isn't found in this domain, 298 * keep trying higher domains in the search list 299 * (if that's enabled). 300 * On a NO_DATA error, keep trying, otherwise 301 * a wildcard entry of another type could keep us 302 * from finding this entry higher in the domain. 303 * If we get some other error (negative answer or 304 * server failure), then stop searching up, 305 * but try the input name below in case it's 306 * fully-qualified. 307 */ 308 if (errno == ECONNREFUSED) { 309 RES_SET_H_ERRNO(statp, TRY_AGAIN); 310 return (-1); 311 } 312 313 switch (statp->res_h_errno) { 314 case NO_DATA: 315 got_nodata++; 316 /* FALLTHROUGH */ 317 case HOST_NOT_FOUND: 318 /* keep trying */ 319 break; 320 case TRY_AGAIN: 321 if (hp->rcode == SERVFAIL) { 322 /* try next search element, if any */ 323 got_servfail++; 324 break; 325 } 326 /* FALLTHROUGH */ 327 default: 328 /* anything else implies that we're done */ 329 done++; 330 } 331 332 /* if we got here for some reason other than DNSRCH, 333 * we only wanted one iteration of the loop, so stop. 334 */ 335 if ((statp->options & RES_DNSRCH) == 0U) 336 done++; 337 } 338 } 339 340 /* 341 * If the query has not already been tried as is then try it 342 * unless RES_NOTLDQUERY is set and there were no dots. 343 */ 344 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 345 !(tried_as_is || root_on_list)) { 346 ret = res_nquerydomain(statp, name, NULL, class, type, 347 answer, anslen); 348 if (ret > 0) 349 return (ret); 350 } 351 352 /* if we got here, we didn't satisfy the search. 353 * if we did an initial full query, return that query's H_ERRNO 354 * (note that we wouldn't be here if that query had succeeded). 355 * else if we ever got a nodata, send that back as the reason. 356 * else send back meaningless H_ERRNO, that being the one from 357 * the last DNSRCH we did. 358 */ 359 if (saved_herrno != -1) 360 RES_SET_H_ERRNO(statp, saved_herrno); 361 else if (got_nodata) 362 RES_SET_H_ERRNO(statp, NO_DATA); 363 else if (got_servfail) 364 RES_SET_H_ERRNO(statp, TRY_AGAIN); 365 return (-1); 366 } 367 368 /* 369 * Perform a call on res_query on the concatenation of name and domain, 370 * removing a trailing dot from name if domain is NULL. 371 */ 372 int 373 res_nquerydomain(res_state statp, 374 const char *name, 375 const char *domain, 376 int class, int type, /* class and type of query */ 377 u_char *answer, /* buffer to put answer */ 378 int anslen) /* size of answer */ 379 { 380 char nbuf[MAXDNAME]; 381 const char *longname = nbuf; 382 int n, d; 383 384 #ifdef DEBUG 385 if (statp->options & RES_DEBUG) 386 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 387 name, domain?domain:"<Nil>", class, type); 388 #endif 389 if (domain == NULL) { 390 /* 391 * Check for trailing '.'; 392 * copy without '.' if present. 393 */ 394 n = strlen(name); 395 if (n >= MAXDNAME) { 396 RES_SET_H_ERRNO(statp, NO_RECOVERY); 397 return (-1); 398 } 399 n--; 400 if (n >= 0 && name[n] == '.') { 401 strncpy(nbuf, name, (size_t)n); 402 nbuf[n] = '\0'; 403 } else 404 longname = name; 405 } else { 406 n = strlen(name); 407 d = strlen(domain); 408 if (n + d + 1 >= MAXDNAME) { 409 RES_SET_H_ERRNO(statp, NO_RECOVERY); 410 return (-1); 411 } 412 sprintf(nbuf, "%s.%s", name, domain); 413 } 414 return (res_nquery(statp, longname, class, type, answer, anslen)); 415 } 416 417 const char * 418 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 419 char *file, *cp1, *cp2; 420 char buf[BUFSIZ]; 421 FILE *fp; 422 423 if (statp->options & RES_NOALIASES) 424 return (NULL); 425 /* 426 * forbid hostaliases for setuid binary, due to possible security 427 * breach. 428 */ 429 if (issetugid()) 430 return (NULL); 431 file = getenv("HOSTALIASES"); 432 if (file == NULL || (fp = fopen(file, "r")) == NULL) 433 return (NULL); 434 setbuf(fp, NULL); 435 buf[sizeof(buf) - 1] = '\0'; 436 while (fgets(buf, sizeof(buf), fp)) { 437 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 438 ; 439 if (!*cp1) 440 break; 441 *cp1 = '\0'; 442 if (ns_samename(buf, name) == 1) { 443 while (isspace((unsigned char)*++cp1)) 444 ; 445 if (!*cp1) 446 break; 447 for (cp2 = cp1 + 1; *cp2 && 448 !isspace((unsigned char)*cp2); ++cp2) 449 ; 450 *cp2 = '\0'; 451 strncpy(dst, cp1, siz - 1); 452 dst[siz - 1] = '\0'; 453 fclose(fp); 454 return (dst); 455 } 456 } 457 fclose(fp); 458 return (NULL); 459 } 460
Indexes created Tue Sep 23 07:09:52 GMT 2025