1/* 2 * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC") 3 * Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium. 4 * 5 * Permission to use, copy, modify, and/or distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 * PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18/* 19 * Copyright (c) 1988, 1993 20 * The Regents of the University of California. All rights reserved. 21 * 22 * Redistribution and use in source and binary forms, with or without 23 * modification, are permitted provided that the following conditions 24 * are met: 25 * 1. Redistributions of source code must retain the above copyright 26 * notice, this list of conditions and the following disclaimer. 27 * 2. Redistributions in binary form must reproduce the above copyright 28 * notice, this list of conditions and the following disclaimer in the 29 * documentation and/or other materials provided with the distribution. 30 * 4. Neither the name of the University nor the names of its contributors 31 * may be used to endorse or promote products derived from this software 32 * without specific prior written permission. 33 * 34 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 35 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 36 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 37 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 38 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 39 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 40 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 41 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 42 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 43 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 44 * SUCH DAMAGE. 45 */ 46 47/* 48 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 49 * 50 * Permission to use, copy, modify, and distribute this software for any 51 * purpose with or without fee is hereby granted, provided that the above 52 * copyright notice and this permission notice appear in all copies, and that 53 * the name of Digital Equipment Corporation not be used in advertising or 54 * publicity pertaining to distribution of the document or software without 55 * specific, written prior permission. 56 * 57 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 58 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 59 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 60 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 61 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 62 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 63 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 64 * SOFTWARE. 65 */ 66 67#if defined(LIBC_SCCS) && !defined(lint) 68static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 69static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $"; 70#endif /* LIBC_SCCS and not lint */ 71#include <sys/cdefs.h> 72__FBSDID("$FreeBSD$"); 73 74#include "port_before.h" 75#include <sys/types.h> 76#include <sys/param.h> 77#include <netinet/in.h> 78#include <arpa/inet.h> 79#include <arpa/nameser.h> 80#include <ctype.h> 81#include <errno.h> 82#include <netdb.h> 83#include <resolv.h> 84#include <stdio.h> 85#include <stdlib.h> 86#include <string.h> 87#include <unistd.h> 88#include "port_after.h" 89 90/* Options. Leave them on. */ 91#ifndef DEBUG 92#define DEBUG 93#endif 94 95#if PACKETSZ > 1024 96#define MAXPACKET PACKETSZ 97#else 98#define MAXPACKET 1024 99#endif 100 101/*% 102 * Formulate a normal query, send, and await answer. 103 * Returned answer is placed in supplied buffer "answer". 104 * Perform preliminary check of answer, returning success only 105 * if no error is indicated and the answer count is nonzero. 106 * Return the size of the response on success, -1 on error. 107 * Error number is left in H_ERRNO. 108 * 109 * Caller must parse answer and determine whether it answers the question. 110 */ 111int 112res_nquery(res_state statp, 113 const char *name, /*%< domain name */ 114 int class, int type, /*%< class and type of query */ 115 u_char *answer, /*%< buffer to put answer */ 116 int anslen) /*%< size of answer buffer */ 117{ 118 u_char buf[MAXPACKET]; 119 HEADER *hp = (HEADER *) answer; 120 u_int oflags; 121 u_char *rdata; 122 int n; 123 124 oflags = statp->_flags; 125 126again: 127 hp->rcode = NOERROR; /*%< default */ 128#ifdef DEBUG 129 if (statp->options & RES_DEBUG) 130 printf(";; res_query(%s, %d, %d)\n", name, class, type); 131#endif 132 133 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 134 buf, sizeof(buf)); 135#ifdef RES_USE_EDNS0 136 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 137 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) { 138 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 139 if (n > 0 && (statp->options & RES_NSID) != 0U) { 140 rdata = &buf[n]; 141 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 142 NS_OPT_NSID, 0, NULL); 143 } 144 } 145#endif 146 if (n <= 0) { 147#ifdef DEBUG 148 if (statp->options & RES_DEBUG) 149 printf(";; res_query: mkquery failed\n"); 150#endif 151 RES_SET_H_ERRNO(statp, NO_RECOVERY); 152 return (n); 153 } 154 155 n = res_nsend(statp, buf, n, answer, anslen); 156 if (n < 0) { 157#ifdef RES_USE_EDNS0 158 /* if the query choked with EDNS0, retry without EDNS0 */ 159 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 160 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 161 statp->_flags |= RES_F_EDNS0ERR; 162 if (statp->options & RES_DEBUG) 163 printf(";; res_nquery: retry without EDNS0\n"); 164 goto again; 165 } 166#endif 167#ifdef DEBUG 168 if (statp->options & RES_DEBUG) 169 printf(";; res_query: send error\n"); 170#endif 171 RES_SET_H_ERRNO(statp, TRY_AGAIN); 172 return (n); 173 } 174 175 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 176#ifdef DEBUG 177 if (statp->options & RES_DEBUG) 178 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 179 p_rcode(hp->rcode), 180 ntohs(hp->ancount), 181 ntohs(hp->nscount), 182 ntohs(hp->arcount)); 183#endif 184 switch (hp->rcode) { 185 case NXDOMAIN: 186 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 187 break; 188 case SERVFAIL: 189 RES_SET_H_ERRNO(statp, TRY_AGAIN); 190 break; 191 case NOERROR: 192 RES_SET_H_ERRNO(statp, NO_DATA); 193 break; 194 case FORMERR: 195 case NOTIMP: 196 case REFUSED: 197 default: 198 RES_SET_H_ERRNO(statp, NO_RECOVERY); 199 break; 200 } 201 return (-1); 202 } 203 return (n); 204} 205 206/*% 207 * Formulate a normal query, send, and retrieve answer in supplied buffer. 208 * Return the size of the response on success, -1 on error. 209 * If enabled, implement search rules until answer or unrecoverable failure 210 * is detected. Error code, if any, is left in H_ERRNO. 211 */ 212int 213res_nsearch(res_state statp, 214 const char *name, /*%< domain name */ 215 int class, int type, /*%< class and type of query */ 216 u_char *answer, /*%< buffer to put answer */ 217 int anslen) /*%< size of answer */ 218{ 219 const char *cp, * const *domain; 220 HEADER *hp = (HEADER *) answer; 221 char tmp[NS_MAXDNAME]; 222 u_int dots; 223 int trailing_dot, ret, saved_herrno; 224 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 225 int tried_as_is = 0; 226 int searched = 0; 227 228 errno = 0; 229 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 230 dots = 0; 231 for (cp = name; *cp != '\0'; cp++) 232 dots += (*cp == '.'); 233 trailing_dot = 0; 234 if (cp > name && *--cp == '.') 235 trailing_dot++; 236 237 /* If there aren't any dots, it could be a user-level alias. */ 238 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 239 return (res_nquery(statp, cp, class, type, answer, anslen)); 240 241 /* 242 * If there are enough dots in the name, let's just give it a 243 * try 'as is'. The threshold can be set with the "ndots" option. 244 * Also, query 'as is', if there is a trailing dot in the name. 245 */ 246 saved_herrno = -1; 247 if (dots >= statp->ndots || trailing_dot) { 248 ret = res_nquerydomain(statp, name, NULL, class, type, 249 answer, anslen); 250 if (ret > 0 || trailing_dot) 251 return (ret); 252 if (errno == ECONNREFUSED) { 253 RES_SET_H_ERRNO(statp, TRY_AGAIN); 254 return (-1); 255 } 256 switch (statp->res_h_errno) { 257 case NO_DATA: 258 case HOST_NOT_FOUND: 259 break; 260 case TRY_AGAIN: 261 if (hp->rcode == SERVFAIL) 262 break; 263 /* FALLTHROUGH */ 264 default: 265 return (-1); 266 } 267 saved_herrno = statp->res_h_errno; 268 tried_as_is++; 269 } 270 271 /* 272 * We do at least one level of search if 273 * - there is no dot and RES_DEFNAME is set, or 274 * - there is at least one dot, there is no trailing dot, 275 * and RES_DNSRCH is set. 276 */ 277 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 278 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 279 int done = 0; 280 281 for (domain = (const char * const *)statp->dnsrch; 282 *domain && !done; 283 domain++) { 284 searched = 1; 285 286 if (domain[0][0] == '\0' || 287 (domain[0][0] == '.' && domain[0][1] == '\0')) 288 root_on_list++; 289 290 if (root_on_list && tried_as_is) 291 continue; 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 /* 326 * This can occur due to a server failure 327 * (that is, all listed servers have failed), 328 * or all listed servers have timed out. 329 * ((HEADER *)answer)->rcode may not be set 330 * to SERVFAIL in the case of a timeout. 331 * 332 * Either way we must return TRY_AGAIN in 333 * order to avoid non-deterministic 334 * return codes. 335 * For example, loaded name servers or races 336 * against network startup/validation (dhcp, 337 * ppp, etc) can cause the search to timeout 338 * on one search element, e.g. 'fu.bar.com', 339 * and return a definitive failure on the 340 * next search element, e.g. 'fu.'. 341 */ 342 got_servfail++; 343 if (hp->rcode == SERVFAIL) { 344 /* try next search element, if any */ 345 break; 346 } 347 /* FALLTHROUGH */ 348 default: 349 /* anything else implies that we're done */ 350 done++; 351 } 352 353 /* if we got here for some reason other than DNSRCH, 354 * we only wanted one iteration of the loop, so stop. 355 */ 356 if ((statp->options & RES_DNSRCH) == 0U) 357 done++; 358 } 359 } 360 361 switch (statp->res_h_errno) { 362 case NO_DATA: 363 case HOST_NOT_FOUND: 364 break; 365 case TRY_AGAIN: 366 if (hp->rcode == SERVFAIL) 367 break; 368 /* FALLTHROUGH */ 369 default: 370 goto giveup; 371 } 372 373 /* 374 * If the query has not already been tried as is then try it 375 * unless RES_NOTLDQUERY is set and there were no dots. 376 */ 377 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 378 !(tried_as_is || root_on_list)) { 379 ret = res_nquerydomain(statp, name, NULL, class, type, 380 answer, anslen); 381 if (ret > 0) 382 return (ret); 383 } 384 385 /* if we got here, we didn't satisfy the search. 386 * if we did an initial full query, return that query's H_ERRNO 387 * (note that we wouldn't be here if that query had succeeded). 388 * else if we ever got a nodata, send that back as the reason. 389 * else send back meaningless H_ERRNO, that being the one from 390 * the last DNSRCH we did. 391 */ 392giveup: 393 if (saved_herrno != -1) 394 RES_SET_H_ERRNO(statp, saved_herrno); 395 else if (got_nodata) 396 RES_SET_H_ERRNO(statp, NO_DATA); 397 else if (got_servfail) 398 RES_SET_H_ERRNO(statp, TRY_AGAIN); 399 return (-1); 400} 401 402/*% 403 * Perform a call on res_query on the concatenation of name and domain, 404 * removing a trailing dot from name if domain is NULL. 405 */ 406int 407res_nquerydomain(res_state statp, 408 const char *name, 409 const char *domain, 410 int class, int type, /*%< class and type of query */ 411 u_char *answer, /*%< buffer to put answer */ 412 int anslen) /*%< size of answer */ 413{ 414 char nbuf[MAXDNAME]; 415 const char *longname = nbuf; 416 int n, d; 417 418#ifdef DEBUG 419 if (statp->options & RES_DEBUG) 420 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 421 name, domain?domain:"<Nil>", class, type); 422#endif 423 if (domain == NULL) { 424 /* 425 * Check for trailing '.'; 426 * copy without '.' if present. 427 */ 428 n = strlen(name); 429 if (n >= MAXDNAME) { 430 RES_SET_H_ERRNO(statp, NO_RECOVERY); 431 return (-1); 432 } 433 n--; 434 if (n >= 0 && name[n] == '.') { 435 strncpy(nbuf, name, n); 436 nbuf[n] = '\0'; 437 } else 438 longname = name; 439 } else { 440 n = strlen(name); 441 d = strlen(domain); 442 if (n + d + 1 >= MAXDNAME) { 443 RES_SET_H_ERRNO(statp, NO_RECOVERY); 444 return (-1); 445 } 446 sprintf(nbuf, "%s.%s", name, domain); 447 } 448 return (res_nquery(statp, longname, class, type, answer, anslen)); 449} 450 451const char * 452res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 453 char *file, *cp1, *cp2; 454 char buf[BUFSIZ]; 455 FILE *fp; 456 457 if (statp->options & RES_NOALIASES) 458 return (NULL); 459 if (issetugid()) 460 return (NULL); 461 file = getenv("HOSTALIASES"); 462 if (file == NULL || (fp = fopen(file, "re")) == NULL) 463 return (NULL); 464 setbuf(fp, NULL); 465 buf[sizeof(buf) - 1] = '\0'; 466 while (fgets(buf, sizeof(buf), fp)) { 467 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 468 ; 469 if (!*cp1) 470 break; 471 *cp1 = '\0'; 472 if (ns_samename(buf, name) == 1) { 473 while (isspace((unsigned char)*++cp1)) 474 ; 475 if (!*cp1) 476 break; 477 for (cp2 = cp1 + 1; *cp2 && 478 !isspace((unsigned char)*cp2); ++cp2) 479 ; 480 *cp2 = '\0'; 481 strncpy(dst, cp1, siz - 1); 482 dst[siz - 1] = '\0'; 483 fclose(fp); 484 return (dst); 485 } 486 } 487 fclose(fp); 488 return (NULL); 489} 490 491/*! \file */ 492