1 /* $NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 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. All advertising materials mentioning features or use of this software 33 * must display the following acknowledgement: 34 * This product includes software developed by the University of 35 * California, Berkeley and its contributors. 36 * 4. Neither the name of the University nor the names of its contributors 37 * may be used to endorse or promote products derived from this software 38 * without specific prior written permission. 39 * 40 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 43 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 */ 52 53 /* 54 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 55 * 56 * Permission to use, copy, modify, and distribute this software for any 57 * purpose with or without fee is hereby granted, provided that the above 58 * copyright notice and this permission notice appear in all copies, and that 59 * the name of Digital Equipment Corporation not be used in advertising or 60 * publicity pertaining to distribution of the document or software without 61 * specific, written prior permission. 62 * 63 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 64 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 65 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 66 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 67 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 68 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 69 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 70 * SOFTWARE. 71 */ 72 73 /* 74 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 75 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 76 * 77 * Permission to use, copy, modify, and distribute this software for any 78 * purpose with or without fee is hereby granted, provided that the above 79 * copyright notice and this permission notice appear in all copies. 80 * 81 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 82 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 83 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 84 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 85 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 86 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 87 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 88 */ 89 90 #include <sys/cdefs.h> 91 #if defined(LIBC_SCCS) && !defined(lint) 92 #ifdef notdef 93 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 94 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp"; 95 #else 96 __RCSID("$NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $"); 97 #endif 98 #endif /* LIBC_SCCS and not lint */ 99 100 #include "port_before.h" 101 102 #include "namespace.h" 103 #include <sys/types.h> 104 #include <sys/param.h> 105 #include <netinet/in.h> 106 #include <arpa/inet.h> 107 #include <arpa/nameser.h> 108 #include <ctype.h> 109 #include <errno.h> 110 #include <netdb.h> 111 #include <resolv.h> 112 #include <stdio.h> 113 #include <stdlib.h> 114 #include <unistd.h> 115 #include <string.h> 116 #include "port_after.h" 117 118 #if 0 119 #ifdef __weak_alias 120 __weak_alias(res_nquery,_res_nquery) 121 __weak_alias(res_nsearch,_res_nsearch) 122 __weak_alias(res_nquerydomain,__res_nquerydomain) 123 __weak_alias(res_hostalias,__res_hostalias) 124 #endif 125 #endif 126 127 /* Options. Leave them on. */ 128 #ifndef DEBUG 129 #define DEBUG 130 #endif 131 132 #if PACKETSZ > 1024 133 #define MAXPACKET PACKETSZ 134 #else 135 #define MAXPACKET 1024 136 #endif 137 138 /*% 139 * Formulate a normal query, send, and await answer. 140 * Returned answer is placed in supplied buffer "answer". 141 * Perform preliminary check of answer, returning success only 142 * if no error is indicated and the answer count is nonzero. 143 * Return the size of the response on success, -1 on error. 144 * Error number is left in H_ERRNO. 145 * 146 * Caller must parse answer and determine whether it answers the question. 147 */ 148 int 149 res_nquery(res_state statp, 150 const char *name, /*%< domain name */ 151 int class, int type, /*%< class and type of query */ 152 u_char *answer, /*%< buffer to put answer */ 153 int anslen) /*%< size of answer buffer */ 154 { 155 u_char buf[MAXPACKET]; 156 HEADER *hp = (HEADER *)(void *)answer; 157 u_int oflags; 158 u_char *rdata; 159 int n; 160 161 oflags = statp->_flags; 162 163 again: 164 hp->rcode = NOERROR; /*%< default */ 165 #ifdef DEBUG 166 if (statp->options & RES_DEBUG) 167 printf(";; res_query(%s, %d, %d)\n", name, class, type); 168 #endif 169 170 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 171 buf, sizeof(buf)); 172 #ifdef RES_USE_EDNS0 173 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 174 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) { 175 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 176 rdata = &buf[n]; 177 if (n > 0 && (statp->options & RES_NSID) != 0U) { 178 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 179 NS_OPT_NSID, 0, NULL); 180 } 181 } 182 #endif 183 if (n <= 0) { 184 #ifdef DEBUG 185 if (statp->options & RES_DEBUG) 186 printf(";; res_query: mkquery failed\n"); 187 #endif 188 RES_SET_H_ERRNO(statp, NO_RECOVERY); 189 return (n); 190 } 191 192 n = res_nsend(statp, buf, n, answer, anslen); 193 if (n < 0) { 194 #ifdef RES_USE_EDNS0 195 /* if the query choked with EDNS0, retry without EDNS0 */ 196 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 197 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 198 statp->_flags |= RES_F_EDNS0ERR; 199 if (statp->options & RES_DEBUG) 200 printf(";; res_nquery: retry without EDNS0\n"); 201 goto again; 202 } 203 #endif 204 #ifdef DEBUG 205 if (statp->options & RES_DEBUG) 206 printf(";; res_query: send error\n"); 207 #endif 208 RES_SET_H_ERRNO(statp, TRY_AGAIN); 209 return (n); 210 } 211 212 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 213 #ifdef DEBUG 214 if (statp->options & RES_DEBUG) 215 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 216 p_rcode(hp->rcode), 217 ntohs(hp->ancount), 218 ntohs(hp->nscount), 219 ntohs(hp->arcount)); 220 #endif 221 switch (hp->rcode) { 222 case NXDOMAIN: 223 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 224 break; 225 case SERVFAIL: 226 RES_SET_H_ERRNO(statp, TRY_AGAIN); 227 break; 228 case NOERROR: 229 RES_SET_H_ERRNO(statp, NO_DATA); 230 break; 231 case FORMERR: 232 case NOTIMP: 233 case REFUSED: 234 default: 235 RES_SET_H_ERRNO(statp, NO_RECOVERY); 236 break; 237 } 238 return (-1); 239 } 240 return (n); 241 } 242 243 /*% 244 * Formulate a normal query, send, and retrieve answer in supplied buffer. 245 * Return the size of the response on success, -1 on error. 246 * If enabled, implement search rules until answer or unrecoverable failure 247 * is detected. Error code, if any, is left in H_ERRNO. 248 */ 249 int 250 res_nsearch(res_state statp, 251 const char *name, /*%< domain name */ 252 int class, int type, /*%< class and type of query */ 253 u_char *answer, /*%< buffer to put answer */ 254 int anslen) /*%< size of answer */ 255 { 256 const char *cp, * const *domain; 257 HEADER *hp = (HEADER *)(void *)answer; 258 char tmp[NS_MAXDNAME]; 259 u_int dots; 260 int trailing_dot, ret, saved_herrno; 261 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 262 int tried_as_is = 0; 263 int searched = 0; 264 265 errno = 0; 266 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 267 dots = 0; 268 for (cp = name; *cp != '\0'; cp++) 269 dots += (*cp == '.'); 270 trailing_dot = 0; 271 if (cp > name && *--cp == '.') 272 trailing_dot++; 273 274 /* If there aren't any dots, it could be a user-level alias. */ 275 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 276 return (res_nquery(statp, cp, class, type, answer, anslen)); 277 278 /* 279 * If there are enough dots in the name, let's just give it a 280 * try 'as is'. The threshold can be set with the "ndots" option. 281 * Also, query 'as is', if there is a trailing dot in the name. 282 */ 283 saved_herrno = -1; 284 if (dots >= statp->ndots || trailing_dot) { 285 ret = res_nquerydomain(statp, name, NULL, class, type, 286 answer, anslen); 287 if (ret > 0 || trailing_dot) 288 return (ret); 289 saved_herrno = statp->res_h_errno; 290 tried_as_is++; 291 } 292 293 /* 294 * We do at least one level of search if 295 * - there is no dot and RES_DEFNAME is set, or 296 * - there is at least one dot, there is no trailing dot, 297 * and RES_DNSRCH is set. 298 */ 299 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 300 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 301 int done = 0; 302 303 for (domain = (const char * const *)statp->dnsrch; 304 *domain && !done; 305 domain++) { 306 searched = 1; 307 308 if (domain[0][0] == '\0' || 309 (domain[0][0] == '.' && domain[0][1] == '\0')) 310 root_on_list++; 311 312 ret = res_nquerydomain(statp, name, *domain, 313 class, type, 314 answer, anslen); 315 if (ret > 0) 316 return (ret); 317 318 /* 319 * If no server present, give up. 320 * If name isn't found in this domain, 321 * keep trying higher domains in the search list 322 * (if that's enabled). 323 * On a NO_DATA error, keep trying, otherwise 324 * a wildcard entry of another type could keep us 325 * from finding this entry higher in the domain. 326 * If we get some other error (negative answer or 327 * server failure), then stop searching up, 328 * but try the input name below in case it's 329 * fully-qualified. 330 */ 331 if (errno == ECONNREFUSED) { 332 RES_SET_H_ERRNO(statp, TRY_AGAIN); 333 return (-1); 334 } 335 336 switch (statp->res_h_errno) { 337 case NO_DATA: 338 got_nodata++; 339 /* FALLTHROUGH */ 340 case HOST_NOT_FOUND: 341 /* keep trying */ 342 break; 343 case TRY_AGAIN: 344 if (hp->rcode == SERVFAIL) { 345 /* try next search element, if any */ 346 got_servfail++; 347 break; 348 } 349 /* FALLTHROUGH */ 350 default: 351 /* anything else implies that we're done */ 352 done++; 353 } 354 355 /* if we got here for some reason other than DNSRCH, 356 * we only wanted one iteration of the loop, so stop. 357 */ 358 if ((statp->options & RES_DNSRCH) == 0U) 359 done++; 360 } 361 } 362 363 /* 364 * If the query has not already been tried as is then try it 365 * unless RES_NOTLDQUERY is set and there were no dots. 366 */ 367 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 368 !(tried_as_is || root_on_list)) { 369 ret = res_nquerydomain(statp, name, NULL, class, type, 370 answer, anslen); 371 if (ret > 0) 372 return (ret); 373 } 374 375 /* if we got here, we didn't satisfy the search. 376 * if we did an initial full query, return that query's H_ERRNO 377 * (note that we wouldn't be here if that query had succeeded). 378 * else if we ever got a nodata, send that back as the reason. 379 * else send back meaningless H_ERRNO, that being the one from 380 * the last DNSRCH we did. 381 */ 382 if (saved_herrno != -1) 383 RES_SET_H_ERRNO(statp, saved_herrno); 384 else if (got_nodata) 385 RES_SET_H_ERRNO(statp, NO_DATA); 386 else if (got_servfail) 387 RES_SET_H_ERRNO(statp, TRY_AGAIN); 388 return (-1); 389 } 390 391 /*% 392 * Perform a call on res_query on the concatenation of name and domain, 393 * removing a trailing dot from name if domain is NULL. 394 */ 395 int 396 res_nquerydomain(res_state statp, 397 const char *name, 398 const char *domain, 399 int class, int type, /*%< class and type of query */ 400 u_char *answer, /*%< buffer to put answer */ 401 int anslen) /*%< size of answer */ 402 { 403 char nbuf[MAXDNAME]; 404 const char *longname = nbuf; 405 int n, d; 406 407 #ifdef DEBUG 408 if (statp->options & RES_DEBUG) 409 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 410 name, domain?domain:"<Nil>", class, type); 411 #endif 412 if (domain == NULL) { 413 /* 414 * Check for trailing '.'; 415 * copy without '.' if present. 416 */ 417 n = strlen(name); 418 if (n >= MAXDNAME) { 419 RES_SET_H_ERRNO(statp, NO_RECOVERY); 420 return (-1); 421 } 422 n--; 423 if (n >= 0 && name[n] == '.') { 424 strncpy(nbuf, name, (size_t)n); 425 nbuf[n] = '\0'; 426 } else 427 longname = name; 428 } else { 429 n = strlen(name); 430 d = strlen(domain); 431 if (n + d + 1 >= MAXDNAME) { 432 RES_SET_H_ERRNO(statp, NO_RECOVERY); 433 return (-1); 434 } 435 sprintf(nbuf, "%s.%s", name, domain); 436 } 437 return (res_nquery(statp, longname, class, type, answer, anslen)); 438 } 439 440 const char * 441 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 442 char *file, *cp1, *cp2; 443 char buf[BUFSIZ]; 444 FILE *fp; 445 446 if (statp->options & RES_NOALIASES) 447 return (NULL); 448 /* 449 * forbid hostaliases for setuid binary, due to possible security 450 * breach. 451 */ 452 if (issetugid()) 453 return (NULL); 454 file = getenv("HOSTALIASES"); 455 if (file == NULL || (fp = fopen(file, "r")) == NULL) 456 return (NULL); 457 buf[sizeof(buf) - 1] = '\0'; 458 while (fgets(buf, sizeof(buf), fp)) { 459 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 460 ; 461 if (!*cp1) 462 break; 463 *cp1 = '\0'; 464 if (ns_samename(buf, name) == 1) { 465 while (isspace((unsigned char)*++cp1)) 466 ; 467 if (!*cp1) 468 break; 469 for (cp2 = cp1 + 1; *cp2 && 470 !isspace((unsigned char)*cp2); ++cp2) 471 ; 472 *cp2 = '\0'; 473 strncpy(dst, cp1, siz - 1); 474 dst[siz - 1] = '\0'; 475 fclose(fp); 476 return (dst); 477 } 478 } 479 fclose(fp); 480 return (NULL); 481 } 482 483 /*! \file */ 484