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. 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) 68 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 69 static 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/param.h> 76 #include <netinet/in.h> 77 #include <arpa/inet.h> 78 #include <arpa/nameser.h> 79 #include <ctype.h> 80 #include <errno.h> 81 #include <netdb.h> 82 #include <resolv.h> 83 #include <stdio.h> 84 #include <stdlib.h> 85 #include <string.h> 86 #include <unistd.h> 87 #include "port_after.h" 88 89 /* Options. Leave them on. */ 90 #ifndef DEBUG 91 #define DEBUG 92 #endif 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 */ 110 int 111 res_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; 124 125 again: 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 if (n > 0 && (statp->options & RES_NSID) != 0U) { 139 rdata = &buf[n]; 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 */ 211 int 212 res_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 if (errno == ECONNREFUSED) { 252 RES_SET_H_ERRNO(statp, TRY_AGAIN); 253 return (-1); 254 } 255 switch (statp->res_h_errno) { 256 case NO_DATA: 257 case HOST_NOT_FOUND: 258 break; 259 case TRY_AGAIN: 260 if (hp->rcode == SERVFAIL) 261 break; 262 /* FALLTHROUGH */ 263 default: 264 return (-1); 265 } 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 if (root_on_list && tried_as_is) 290 continue; 291 292 ret = res_nquerydomain(statp, name, *domain, 293 class, type, 294 answer, anslen); 295 if (ret > 0) 296 return (ret); 297 298 /* 299 * If no server present, give up. 300 * If name isn't found in this domain, 301 * keep trying higher domains in the search list 302 * (if that's enabled). 303 * On a NO_DATA error, keep trying, otherwise 304 * a wildcard entry of another type could keep us 305 * from finding this entry higher in the domain. 306 * If we get some other error (negative answer or 307 * server failure), then stop searching up, 308 * but try the input name below in case it's 309 * fully-qualified. 310 */ 311 if (errno == ECONNREFUSED) { 312 RES_SET_H_ERRNO(statp, TRY_AGAIN); 313 return (-1); 314 } 315 316 switch (statp->res_h_errno) { 317 case NO_DATA: 318 got_nodata++; 319 /* FALLTHROUGH */ 320 case HOST_NOT_FOUND: 321 /* keep trying */ 322 break; 323 case TRY_AGAIN: 324 /* 325 * This can occur due to a server failure 326 * (that is, all listed servers have failed), 327 * or all listed servers have timed out. 328 * ((HEADER *)answer)->rcode may not be set 329 * to SERVFAIL in the case of a timeout. 330 * 331 * Either way we must return TRY_AGAIN in 332 * order to avoid non-deterministic 333 * return codes. 334 * For example, loaded name servers or races 335 * against network startup/validation (dhcp, 336 * ppp, etc) can cause the search to timeout 337 * on one search element, e.g. 'fu.bar.com', 338 * and return a definitive failure on the 339 * next search element, e.g. 'fu.'. 340 */ 341 got_servfail++; 342 if (hp->rcode == SERVFAIL) { 343 /* try next search element, if any */ 344 break; 345 } 346 /* FALLTHROUGH */ 347 default: 348 /* anything else implies that we're done */ 349 done++; 350 } 351 352 /* if we got here for some reason other than DNSRCH, 353 * we only wanted one iteration of the loop, so stop. 354 */ 355 if ((statp->options & RES_DNSRCH) == 0U) 356 done++; 357 } 358 } 359 360 switch (statp->res_h_errno) { 361 case NO_DATA: 362 case HOST_NOT_FOUND: 363 break; 364 case TRY_AGAIN: 365 if (hp->rcode == SERVFAIL) 366 break; 367 /* FALLTHROUGH */ 368 default: 369 goto giveup; 370 } 371 372 /* 373 * If the query has not already been tried as is then try it 374 * unless RES_NOTLDQUERY is set and there were no dots. 375 */ 376 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 377 !(tried_as_is || root_on_list)) { 378 ret = res_nquerydomain(statp, name, NULL, class, type, 379 answer, anslen); 380 if (ret > 0) 381 return (ret); 382 } 383 384 /* if we got here, we didn't satisfy the search. 385 * if we did an initial full query, return that query's H_ERRNO 386 * (note that we wouldn't be here if that query had succeeded). 387 * else if we ever got a nodata, send that back as the reason. 388 * else send back meaningless H_ERRNO, that being the one from 389 * the last DNSRCH we did. 390 */ 391 giveup: 392 if (saved_herrno != -1) 393 RES_SET_H_ERRNO(statp, saved_herrno); 394 else if (got_nodata) 395 RES_SET_H_ERRNO(statp, NO_DATA); 396 else if (got_servfail) 397 RES_SET_H_ERRNO(statp, TRY_AGAIN); 398 return (-1); 399 } 400 401 /*% 402 * Perform a call on res_query on the concatenation of name and domain, 403 * removing a trailing dot from name if domain is NULL. 404 */ 405 int 406 res_nquerydomain(res_state statp, 407 const char *name, 408 const char *domain, 409 int class, int type, /*%< class and type of query */ 410 u_char *answer, /*%< buffer to put answer */ 411 int anslen) /*%< size of answer */ 412 { 413 char nbuf[MAXDNAME]; 414 const char *longname = nbuf; 415 int n, d; 416 417 #ifdef DEBUG 418 if (statp->options & RES_DEBUG) 419 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 420 name, domain?domain:"<Nil>", class, type); 421 #endif 422 if (domain == NULL) { 423 /* 424 * Check for trailing '.'; 425 * copy without '.' if present. 426 */ 427 n = strlen(name); 428 if (n >= MAXDNAME) { 429 RES_SET_H_ERRNO(statp, NO_RECOVERY); 430 return (-1); 431 } 432 n--; 433 if (n >= 0 && name[n] == '.') { 434 strncpy(nbuf, name, n); 435 nbuf[n] = '\0'; 436 } else 437 longname = name; 438 } else { 439 n = strlen(name); 440 d = strlen(domain); 441 if (n + d + 1 >= MAXDNAME) { 442 RES_SET_H_ERRNO(statp, NO_RECOVERY); 443 return (-1); 444 } 445 sprintf(nbuf, "%s.%s", name, domain); 446 } 447 return (res_nquery(statp, longname, class, type, answer, anslen)); 448 } 449 450 const char * 451 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 452 char *file, *cp1, *cp2; 453 char buf[BUFSIZ]; 454 FILE *fp; 455 456 if (statp->options & RES_NOALIASES) 457 return (NULL); 458 if (issetugid()) 459 return (NULL); 460 file = getenv("HOSTALIASES"); 461 if (file == NULL || (fp = fopen(file, "re")) == NULL) 462 return (NULL); 463 setbuf(fp, NULL); 464 buf[sizeof(buf) - 1] = '\0'; 465 while (fgets(buf, sizeof(buf), fp)) { 466 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 467 ; 468 if (!*cp1) 469 break; 470 *cp1 = '\0'; 471 if (ns_samename(buf, name) == 1) { 472 while (isspace((unsigned char)*++cp1)) 473 ; 474 if (!*cp1) 475 break; 476 for (cp2 = cp1 + 1; *cp2 && 477 !isspace((unsigned char)*cp2); ++cp2) 478 ; 479 *cp2 = '\0'; 480 strncpy(dst, cp1, siz - 1); 481 dst[siz - 1] = '\0'; 482 fclose(fp); 483 return (dst); 484 } 485 } 486 fclose(fp); 487 return (NULL); 488 } 489 490 /*! \file */ 491