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 * 3. All advertising materials mentioning features or use of this software 31 * must display the following acknowledgement: 32 * This product includes software developed by the University of 33 * California, Berkeley and its contributors. 34 * 4. Neither the name of the University nor the names of its contributors 35 * may be used to endorse or promote products derived from this software 36 * without specific prior written permission. 37 * 38 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 39 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 41 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 42 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 43 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 44 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 45 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 46 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 47 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 */ 50 51/* 52 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 53 * 54 * Permission to use, copy, modify, and distribute this software for any 55 * purpose with or without fee is hereby granted, provided that the above 56 * copyright notice and this permission notice appear in all copies, and that 57 * the name of Digital Equipment Corporation not be used in advertising or 58 * publicity pertaining to distribution of the document or software without 59 * specific, written prior permission. 60 * 61 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 62 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 63 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 64 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 65 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 66 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 67 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 68 * SOFTWARE. 69 */ 70 71#if defined(LIBC_SCCS) && !defined(lint) 72static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 73static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $"; 74#endif /* LIBC_SCCS and not lint */ 75 76#include "port_before.h" 77#include <sys/types.h> 78#include <sys/param.h> 79#include <netinet/in.h> 80#include <arpa/inet.h> 81#include <arpa/nameser.h> 82#include <ctype.h> 83#include <errno.h> 84#include <netdb.h> 85#include <resolv.h> 86#include <stdio.h> 87#include <stdlib.h> 88#include <string.h> 89#include "port_after.h" 90 91/* Options. Leave them on. */ 92//#define DEBUG 93 94#if PACKETSZ > 1024 95#define MAXPACKET PACKETSZ 96#else 97#define MAXPACKET 1024 98#endif 99 100/*% 101 * Formulate a normal query, send, and await answer. 102 * Returned answer is placed in supplied buffer "answer". 103 * Perform preliminary check of answer, returning success only 104 * if no error is indicated and the answer count is nonzero. 105 * Return the size of the response on success, -1 on error. 106 * Error number is left in H_ERRNO. 107 * 108 * Caller must parse answer and determine whether it answers the question. 109 */ 110int 111res_nquery(res_state statp, 112 const char *name, /*%< domain name */ 113 int class, int type, /*%< class and type of query */ 114 u_char *answer, /*%< buffer to put answer */ 115 int anslen) /*%< size of answer buffer */ 116{ 117 u_char buf[MAXPACKET]; 118 HEADER *hp = (HEADER *) answer; 119 u_int oflags; 120 u_char *rdata; 121 int n; 122 123 oflags = statp->_flags; 124 125again: 126 hp->rcode = NOERROR; /*%< default */ 127#ifdef DEBUG 128 if (statp->options & RES_DEBUG) 129 printf(";; res_query(%s, %d, %d)\n", name, class, type); 130#endif 131 132 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 133 buf, sizeof(buf)); 134#ifdef RES_USE_EDNS0 135 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 136 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) { 137 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 138 rdata = &buf[n]; 139 if (n > 0 && (statp->options & RES_NSID) != 0U) { 140 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 141 NS_OPT_NSID, 0, NULL); 142 } 143 } 144#endif 145 if (n <= 0) { 146#ifdef DEBUG 147 if (statp->options & RES_DEBUG) 148 printf(";; res_query: mkquery failed\n"); 149#endif 150 RES_SET_H_ERRNO(statp, NO_RECOVERY); 151 return (n); 152 } 153 154 n = res_nsend(statp, buf, n, answer, anslen); 155 if (n < 0) { 156#ifdef RES_USE_EDNS0 157 /* if the query choked with EDNS0, retry without EDNS0 */ 158 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 159 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 160 statp->_flags |= RES_F_EDNS0ERR; 161 if (statp->options & RES_DEBUG) 162 printf(";; res_nquery: retry without EDNS0\n"); 163 goto again; 164 } 165#endif 166#ifdef DEBUG 167 if (statp->options & RES_DEBUG) 168 printf(";; res_query: send error\n"); 169#endif 170 RES_SET_H_ERRNO(statp, TRY_AGAIN); 171 return (n); 172 } 173 174 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 175#ifdef DEBUG 176 if (statp->options & RES_DEBUG) 177 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 178 p_rcode(hp->rcode), 179 ntohs(hp->ancount), 180 ntohs(hp->nscount), 181 ntohs(hp->arcount)); 182#endif 183 switch (hp->rcode) { 184 case NXDOMAIN: 185 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 186 break; 187 case SERVFAIL: 188 RES_SET_H_ERRNO(statp, TRY_AGAIN); 189 break; 190 case NOERROR: 191 RES_SET_H_ERRNO(statp, NO_DATA); 192 break; 193 case FORMERR: 194 case NOTIMP: 195 case REFUSED: 196 default: 197 RES_SET_H_ERRNO(statp, NO_RECOVERY); 198 break; 199 } 200 return (-1); 201 } 202 return (n); 203} 204 205/*% 206 * Formulate a normal query, send, and retrieve answer in supplied buffer. 207 * Return the size of the response on success, -1 on error. 208 * If enabled, implement search rules until answer or unrecoverable failure 209 * is detected. Error code, if any, is left in H_ERRNO. 210 */ 211int 212res_nsearch(res_state statp, 213 const char *name, /*%< domain name */ 214 int class, int type, /*%< class and type of query */ 215 u_char *answer, /*%< buffer to put answer */ 216 int anslen) /*%< size of answer */ 217{ 218 const char *cp, * const *domain; 219 HEADER *hp = (HEADER *) answer; 220 char tmp[NS_MAXDNAME]; 221 u_int dots; 222 int trailing_dot, ret, saved_herrno; 223 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 224 int tried_as_is = 0; 225 int searched = 0; 226 227 errno = 0; 228 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 229 dots = 0; 230 for (cp = name; *cp != '\0'; cp++) 231 dots += (*cp == '.'); 232 trailing_dot = 0; 233 if (cp > name && *--cp == '.') 234 trailing_dot++; 235 236 /* If there aren't any dots, it could be a user-level alias. */ 237 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 238 return (res_nquery(statp, cp, class, type, answer, anslen)); 239 240 /* 241 * If there are enough dots in the name, let's just give it a 242 * try 'as is'. The threshold can be set with the "ndots" option. 243 * Also, query 'as is', if there is a trailing dot in the name. 244 */ 245 saved_herrno = -1; 246 if (dots >= statp->ndots || trailing_dot) { 247 ret = res_nquerydomain(statp, name, NULL, class, type, 248 answer, anslen); 249 if (ret > 0 || trailing_dot) 250 return (ret); 251 saved_herrno = statp->res_h_errno; 252 tried_as_is++; 253 } 254 255 /* 256 * We do at least one level of search if 257 * - there is no dot and RES_DEFNAME is set, or 258 * - there is at least one dot, there is no trailing dot, 259 * and RES_DNSRCH is set. 260 */ 261 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 262 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 263 int done = 0; 264 265 for (domain = (const char * const *)statp->dnsrch; 266 *domain && !done; 267 domain++) { 268 searched = 1; 269 270 if (domain[0][0] == '\0' || 271 (domain[0][0] == '.' && domain[0][1] == '\0')) 272 root_on_list++; 273 274 ret = res_nquerydomain(statp, name, *domain, 275 class, type, 276 answer, anslen); 277 if (ret > 0) 278 return (ret); 279 280 /* 281 * If no server present, give up. 282 * If name isn't found in this domain, 283 * keep trying higher domains in the search list 284 * (if that's enabled). 285 * On a NO_DATA error, keep trying, otherwise 286 * a wildcard entry of another type could keep us 287 * from finding this entry higher in the domain. 288 * If we get some other error (negative answer or 289 * server failure), then stop searching up, 290 * but try the input name below in case it's 291 * fully-qualified. 292 */ 293 if (errno == ECONNREFUSED) { 294 RES_SET_H_ERRNO(statp, TRY_AGAIN); 295 return (-1); 296 } 297 298 switch (statp->res_h_errno) { 299 case NO_DATA: 300 got_nodata++; 301 /* FALLTHROUGH */ 302 case HOST_NOT_FOUND: 303 /* keep trying */ 304 break; 305 case TRY_AGAIN: 306 if (hp->rcode == SERVFAIL) { 307 /* try next search element, if any */ 308 got_servfail++; 309 break; 310 } 311 /* FALLTHROUGH */ 312 default: 313 /* anything else implies that we're done */ 314 done++; 315 } 316 317 /* if we got here for some reason other than DNSRCH, 318 * we only wanted one iteration of the loop, so stop. 319 */ 320 if ((statp->options & RES_DNSRCH) == 0U) 321 done++; 322 } 323 } 324 325 /* 326 * If the query has not already been tried as is then try it 327 * unless RES_NOTLDQUERY is set and there were no dots. 328 */ 329 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 330 !(tried_as_is || root_on_list)) { 331 ret = res_nquerydomain(statp, name, NULL, class, type, 332 answer, anslen); 333 if (ret > 0) 334 return (ret); 335 } 336 337 /* if we got here, we didn't satisfy the search. 338 * if we did an initial full query, return that query's H_ERRNO 339 * (note that we wouldn't be here if that query had succeeded). 340 * else if we ever got a nodata, send that back as the reason. 341 * else send back meaningless H_ERRNO, that being the one from 342 * the last DNSRCH we did. 343 */ 344 if (saved_herrno != -1) 345 RES_SET_H_ERRNO(statp, saved_herrno); 346 else if (got_nodata) 347 RES_SET_H_ERRNO(statp, NO_DATA); 348 else if (got_servfail) 349 RES_SET_H_ERRNO(statp, TRY_AGAIN); 350 return (-1); 351} 352 353/*% 354 * Perform a call on res_query on the concatenation of name and domain, 355 * removing a trailing dot from name if domain is NULL. 356 */ 357int 358res_nquerydomain(res_state statp, 359 const char *name, 360 const char *domain, 361 int class, int type, /*%< class and type of query */ 362 u_char *answer, /*%< buffer to put answer */ 363 int anslen) /*%< size of answer */ 364{ 365 char nbuf[MAXDNAME]; 366 const char *longname = nbuf; 367 int n, d; 368 369#ifdef DEBUG 370 if (statp->options & RES_DEBUG) 371 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 372 name, domain?domain:"<Nil>", class, type); 373#endif 374 if (domain == NULL) { 375 /* 376 * Check for trailing '.'; 377 * copy without '.' if present. 378 */ 379 n = strlen(name); 380 if (n >= MAXDNAME) { 381 RES_SET_H_ERRNO(statp, NO_RECOVERY); 382 return (-1); 383 } 384 n--; 385 if (n >= 0 && name[n] == '.') { 386 strncpy(nbuf, name, n); 387 nbuf[n] = '\0'; 388 } else 389 longname = name; 390 } else { 391 n = strlen(name); 392 d = strlen(domain); 393 if (n + d + 1 >= MAXDNAME) { 394 RES_SET_H_ERRNO(statp, NO_RECOVERY); 395 return (-1); 396 } 397 sprintf(nbuf, "%s.%s", name, domain); 398 } 399 return (res_nquery(statp, longname, class, type, answer, anslen)); 400} 401 402const char * 403res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 404 char *file, *cp1, *cp2; 405 char buf[BUFSIZ]; 406 FILE *fp; 407 408 if (statp->options & RES_NOALIASES) 409 return (NULL); 410 file = getenv("HOSTALIASES"); 411 if (file == NULL || (fp = fopen(file, "r")) == NULL) 412 return (NULL); 413 setbuf(fp, NULL); 414 buf[sizeof(buf) - 1] = '\0'; 415 while (fgets(buf, sizeof(buf), fp)) { 416 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 417 ; 418 if (!*cp1) 419 break; 420 *cp1 = '\0'; 421 if (ns_samename(buf, name) == 1) { 422 while (isspace((unsigned char)*++cp1)) 423 ; 424 if (!*cp1) 425 break; 426 for (cp2 = cp1 + 1; *cp2 && 427 !isspace((unsigned char)*cp2); ++cp2) 428 ; 429 *cp2 = '\0'; 430 strncpy(dst, cp1, siz - 1); 431 dst[siz - 1] = '\0'; 432 fclose(fp); 433 return (dst); 434 } 435 } 436 fclose(fp); 437 return (NULL); 438} 439 440/*! \file */ 441