1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 /* 35 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 36 * 37 * Permission to use, copy, modify, and distribute this software for any 38 * purpose with or without fee is hereby granted, provided that the above 39 * copyright notice and this permission notice appear in all copies, and that 40 * the name of Digital Equipment Corporation not be used in advertising or 41 * publicity pertaining to distribution of the document or software without 42 * specific, written prior permission. 43 * 44 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 45 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 46 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 47 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 48 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 49 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 50 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 51 * SOFTWARE. 52 */ 53 54 /* 55 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 56 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 57 * 58 * Permission to use, copy, modify, and distribute this software for any 59 * purpose with or without fee is hereby granted, provided that the above 60 * copyright notice and this permission notice appear in all copies. 61 * 62 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 63 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 64 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 65 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 66 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 67 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 68 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 69 */ 70 71 #if defined(LIBC_SCCS) && !defined(lint) 72 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 73 static const char rcsid[] = "$Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp $"; 74 #endif /* LIBC_SCCS and not lint */ 75 #include <sys/cdefs.h> 76 __FBSDID("$FreeBSD$"); 77 78 #include "port_before.h" 79 #include <sys/types.h> 80 #include <sys/param.h> 81 #include <netinet/in.h> 82 #include <arpa/inet.h> 83 #include <arpa/nameser.h> 84 #include <ctype.h> 85 #include <errno.h> 86 #include <netdb.h> 87 #include <resolv.h> 88 #include <stdio.h> 89 #include <stdlib.h> 90 #include <string.h> 91 #include <unistd.h> 92 #include "port_after.h" 93 94 /* Options. Leave them on. */ 95 #define DEBUG 96 97 #if PACKETSZ > 1024 98 #define MAXPACKET PACKETSZ 99 #else 100 #define MAXPACKET 1024 101 #endif 102 103 /* 104 * Formulate a normal query, send, and await answer. 105 * Returned answer is placed in supplied buffer "answer". 106 * Perform preliminary check of answer, returning success only 107 * if no error is indicated and the answer count is nonzero. 108 * Return the size of the response on success, -1 on error. 109 * Error number is left in H_ERRNO. 110 * 111 * Caller must parse answer and determine whether it answers the question. 112 */ 113 int 114 res_nquery(res_state statp, 115 const char *name, /* domain name */ 116 int class, int type, /* class and type of query */ 117 u_char *answer, /* buffer to put answer */ 118 int anslen) /* size of answer buffer */ 119 { 120 u_char buf[MAXPACKET]; 121 HEADER *hp = (HEADER *) answer; 122 int n; 123 u_int oflags; 124 125 oflags = statp->_flags; 126 127 again: 128 hp->rcode = NOERROR; /* default */ 129 130 #ifdef DEBUG 131 if (statp->options & RES_DEBUG) 132 printf(";; res_query(%s, %d, %d)\n", name, class, type); 133 #endif 134 135 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 136 buf, sizeof(buf)); 137 #ifdef RES_USE_EDNS0 138 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 139 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U) 140 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 141 #endif 142 if (n <= 0) { 143 #ifdef DEBUG 144 if (statp->options & RES_DEBUG) 145 printf(";; res_query: mkquery failed\n"); 146 #endif 147 RES_SET_H_ERRNO(statp, NO_RECOVERY); 148 return (n); 149 } 150 n = res_nsend(statp, buf, n, answer, anslen); 151 if (n < 0) { 152 #ifdef RES_USE_EDNS0 153 /* if the query choked with EDNS0, retry without EDNS0 */ 154 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 155 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 156 statp->_flags |= RES_F_EDNS0ERR; 157 if (statp->options & RES_DEBUG) 158 printf(";; res_nquery: retry without EDNS0\n"); 159 goto again; 160 } 161 #endif 162 #ifdef DEBUG 163 if (statp->options & RES_DEBUG) 164 printf(";; res_query: send error\n"); 165 #endif 166 RES_SET_H_ERRNO(statp, TRY_AGAIN); 167 return (n); 168 } 169 170 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 171 #ifdef DEBUG 172 if (statp->options & RES_DEBUG) 173 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 174 p_rcode(hp->rcode), 175 ntohs(hp->ancount), 176 ntohs(hp->nscount), 177 ntohs(hp->arcount)); 178 #endif 179 switch (hp->rcode) { 180 case NXDOMAIN: 181 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 182 break; 183 case SERVFAIL: 184 RES_SET_H_ERRNO(statp, TRY_AGAIN); 185 break; 186 case NOERROR: 187 RES_SET_H_ERRNO(statp, NO_DATA); 188 break; 189 case FORMERR: 190 case NOTIMP: 191 case REFUSED: 192 default: 193 RES_SET_H_ERRNO(statp, NO_RECOVERY); 194 break; 195 } 196 return (-1); 197 } 198 return (n); 199 } 200 201 /* 202 * Formulate a normal query, send, and retrieve answer in supplied buffer. 203 * Return the size of the response on success, -1 on error. 204 * If enabled, implement search rules until answer or unrecoverable failure 205 * is detected. Error code, if any, is left in H_ERRNO. 206 */ 207 int 208 res_nsearch(res_state statp, 209 const char *name, /* domain name */ 210 int class, int type, /* class and type of query */ 211 u_char *answer, /* buffer to put answer */ 212 int anslen) /* size of answer */ 213 { 214 const char *cp, * const *domain; 215 char tmp[NS_MAXDNAME]; 216 u_int dots; 217 int trailing_dot, ret, saved_herrno; 218 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 219 int tried_as_is = 0; 220 int searched = 0; 221 222 errno = 0; 223 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ 224 225 dots = 0; 226 for (cp = name; *cp != '\0'; cp++) 227 dots += (*cp == '.'); 228 trailing_dot = 0; 229 if (cp > name && *--cp == '.') 230 trailing_dot++; 231 232 /* If there aren't any dots, it could be a user-level alias. */ 233 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 234 return (res_nquery(statp, cp, class, type, answer, anslen)); 235 236 /* 237 * If there are enough dots in the name, let's just give it a 238 * try 'as is'. The threshold can be set with the "ndots" option. 239 * Also, query 'as is', if there is a trailing dot in the name. 240 */ 241 saved_herrno = -1; 242 if (dots >= statp->ndots || trailing_dot) { 243 ret = res_nquerydomain(statp, name, NULL, class, type, 244 answer, anslen); 245 if (ret > 0 || trailing_dot) 246 return (ret); 247 if (errno == ECONNREFUSED) { 248 RES_SET_H_ERRNO(statp, TRY_AGAIN); 249 return (-1); 250 } 251 switch (statp->res_h_errno) { 252 case NO_DATA: 253 case HOST_NOT_FOUND: 254 break; 255 default: 256 return (-1); 257 } 258 saved_herrno = statp->res_h_errno; 259 tried_as_is++; 260 } 261 262 /* 263 * We do at least one level of search if 264 * - there is no dot and RES_DEFNAME is set, or 265 * - there is at least one dot, there is no trailing dot, 266 * and RES_DNSRCH is set. 267 */ 268 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 269 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 270 int done = 0; 271 272 for (domain = (const char * const *)statp->dnsrch; 273 *domain && !done; 274 domain++) { 275 searched = 1; 276 277 if (domain[0][0] == '\0' || 278 (domain[0][0] == '.' && domain[0][1] == '\0')) 279 root_on_list++; 280 281 if (root_on_list && tried_as_is) 282 continue; 283 284 ret = res_nquerydomain(statp, name, *domain, 285 class, type, 286 answer, anslen); 287 if (ret > 0) 288 return (ret); 289 290 /* 291 * If no server present, give up. 292 * If name isn't found in this domain, 293 * keep trying higher domains in the search list 294 * (if that's enabled). 295 * On a NO_DATA error, keep trying, otherwise 296 * a wildcard entry of another type could keep us 297 * from finding this entry higher in the domain. 298 * If we get some other error (negative answer or 299 * server failure), then stop searching up, 300 * but try the input name below in case it's 301 * fully-qualified. 302 */ 303 if (errno == ECONNREFUSED) { 304 RES_SET_H_ERRNO(statp, TRY_AGAIN); 305 return (-1); 306 } 307 308 switch (statp->res_h_errno) { 309 case NO_DATA: 310 got_nodata++; 311 /* FALLTHROUGH */ 312 case HOST_NOT_FOUND: 313 /* keep trying */ 314 break; 315 case TRY_AGAIN: 316 /* 317 * This can occur due to a server failure 318 * (that is, all listed servers have failed), 319 * or all listed servers have timed out. 320 * ((HEADER *)answer)->rcode may not be set 321 * to SERVFAIL in the case of a timeout. 322 * 323 * Either way we must terminate the search 324 * and return TRY_AGAIN in order to avoid 325 * non-deterministic return codes. For 326 * example, loaded name servers or races 327 * against network startup/validation (dhcp, 328 * ppp, etc) can cause the search to timeout 329 * on one search element, e.g. 'fu.bar.com', 330 * and return a definitive failure on the 331 * next search element, e.g. 'fu.'. 332 */ 333 got_servfail++; 334 /* FALLTHROUGH */ 335 default: 336 /* anything else implies that we're done */ 337 done++; 338 } 339 340 /* if we got here for some reason other than DNSRCH, 341 * we only wanted one iteration of the loop, so stop. 342 */ 343 if ((statp->options & RES_DNSRCH) == 0U) 344 done++; 345 } 346 } 347 348 switch (statp->res_h_errno) { 349 case NO_DATA: 350 case HOST_NOT_FOUND: 351 break; 352 default: 353 goto giveup; 354 } 355 356 /* 357 * If the query has not already been tried as is then try it 358 * unless RES_NOTLDQUERY is set and there were no dots. 359 */ 360 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 361 !(tried_as_is || root_on_list)) { 362 ret = res_nquerydomain(statp, name, NULL, class, type, 363 answer, anslen); 364 if (ret > 0) 365 return (ret); 366 } 367 368 /* if we got here, we didn't satisfy the search. 369 * if we did an initial full query, return that query's H_ERRNO 370 * (note that we wouldn't be here if that query had succeeded). 371 * else if we ever got a nodata, send that back as the reason. 372 * else send back meaningless H_ERRNO, that being the one from 373 * the last DNSRCH we did. 374 */ 375 giveup: 376 if (saved_herrno != -1) 377 RES_SET_H_ERRNO(statp, saved_herrno); 378 else if (got_nodata) 379 RES_SET_H_ERRNO(statp, NO_DATA); 380 else if (got_servfail) 381 RES_SET_H_ERRNO(statp, TRY_AGAIN); 382 return (-1); 383 } 384 385 /* 386 * Perform a call on res_query on the concatenation of name and domain, 387 * removing a trailing dot from name if domain is NULL. 388 */ 389 int 390 res_nquerydomain(res_state statp, 391 const char *name, 392 const char *domain, 393 int class, int type, /* class and type of query */ 394 u_char *answer, /* buffer to put answer */ 395 int anslen) /* size of answer */ 396 { 397 char nbuf[MAXDNAME]; 398 const char *longname = nbuf; 399 int n, d; 400 401 #ifdef DEBUG 402 if (statp->options & RES_DEBUG) 403 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 404 name, domain?domain:"<Nil>", class, type); 405 #endif 406 if (domain == NULL) { 407 /* 408 * Check for trailing '.'; 409 * copy without '.' if present. 410 */ 411 n = strlen(name); 412 if (n >= MAXDNAME) { 413 RES_SET_H_ERRNO(statp, NO_RECOVERY); 414 return (-1); 415 } 416 n--; 417 if (n >= 0 && name[n] == '.') { 418 strncpy(nbuf, name, n); 419 nbuf[n] = '\0'; 420 } else 421 longname = name; 422 } else { 423 n = strlen(name); 424 d = strlen(domain); 425 if (n + d + 1 >= MAXDNAME) { 426 RES_SET_H_ERRNO(statp, NO_RECOVERY); 427 return (-1); 428 } 429 sprintf(nbuf, "%s.%s", name, domain); 430 } 431 return (res_nquery(statp, longname, class, type, answer, anslen)); 432 } 433 434 const char * 435 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 436 char *file, *cp1, *cp2; 437 char buf[BUFSIZ]; 438 FILE *fp; 439 440 if (statp->options & RES_NOALIASES) 441 return (NULL); 442 if (issetugid()) 443 return (NULL); 444 file = getenv("HOSTALIASES"); 445 if (file == NULL || (fp = fopen(file, "r")) == NULL) 446 return (NULL); 447 setbuf(fp, NULL); 448 buf[sizeof(buf) - 1] = '\0'; 449 while (fgets(buf, sizeof(buf), fp)) { 450 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 451 ; 452 if (!*cp1) 453 break; 454 *cp1 = '\0'; 455 if (ns_samename(buf, name) == 1) { 456 while (isspace((unsigned char)*++cp1)) 457 ; 458 if (!*cp1) 459 break; 460 for (cp2 = cp1 + 1; *cp2 && 461 !isspace((unsigned char)*cp2); ++cp2) 462 ; 463 *cp2 = '\0'; 464 strncpy(dst, cp1, siz - 1); 465 dst[siz - 1] = '\0'; 466 fclose(fp); 467 return (dst); 468 } 469 } 470 fclose(fp); 471 return (NULL); 472 } 473