1 /* $NetBSD: res_query.c,v 1.5 2004/05/21 16:03:05 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1988, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by the University of 18 * California, Berkeley and its contributors. 19 * 4. Neither the name of the University nor the names of its contributors 20 * may be used to endorse or promote products derived from this software 21 * without specific prior written permission. 22 * 23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33 * SUCH DAMAGE. 34 */ 35 36 /* 37 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 38 * 39 * Permission to use, copy, modify, and distribute this software for any 40 * purpose with or without fee is hereby granted, provided that the above 41 * copyright notice and this permission notice appear in all copies, and that 42 * the name of Digital Equipment Corporation not be used in advertising or 43 * publicity pertaining to distribution of the document or software without 44 * specific, written prior permission. 45 * 46 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 47 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 48 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 49 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 50 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 51 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 52 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 53 * SOFTWARE. 54 */ 55 56 /* 57 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") 58 * Portions Copyright (c) 1996-1999 by Internet Software Consortium. 59 * 60 * Permission to use, copy, modify, and distribute this software for any 61 * purpose with or without fee is hereby granted, provided that the above 62 * copyright notice and this permission notice appear in all copies. 63 * 64 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES 65 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 66 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR 67 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 68 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 69 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT 70 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 71 */ 72 73 #include <sys/cdefs.h> 74 #if defined(LIBC_SCCS) && !defined(lint) 75 #ifdef notdef 76 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 77 static const char rcsid[] = "Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp"; 78 #else 79 __RCSID("$NetBSD: res_query.c,v 1.5 2004/05/21 16:03:05 christos Exp $"); 80 #endif 81 #endif /* LIBC_SCCS and not lint */ 82 83 #include "port_before.h" 84 85 #include "namespace.h" 86 #include <sys/types.h> 87 #include <sys/param.h> 88 #include <netinet/in.h> 89 #include <arpa/inet.h> 90 #include <arpa/nameser.h> 91 #include <ctype.h> 92 #include <errno.h> 93 #include <netdb.h> 94 #include <resolv.h> 95 #include <stdio.h> 96 #include <stdlib.h> 97 #include <string.h> 98 #include "port_after.h" 99 100 #if 0 101 #ifdef __weak_alias 102 __weak_alias(res_nquery,_res_nquery) 103 __weak_alias(res_nsearch,_res_nsearch) 104 __weak_alias(res_nquerydomain,__res_nquerydomain) 105 __weak_alias(res_hostalias,__res_hostalias) 106 #endif 107 #endif 108 109 /* Options. Leave them on. */ 110 #define DEBUG 111 112 #if PACKETSZ > 1024 113 #define MAXPACKET PACKETSZ 114 #else 115 #define MAXPACKET 1024 116 #endif 117 118 /* 119 * Formulate a normal query, send, and await answer. 120 * Returned answer is placed in supplied buffer "answer". 121 * Perform preliminary check of answer, returning success only 122 * if no error is indicated and the answer count is nonzero. 123 * Return the size of the response on success, -1 on error. 124 * Error number is left in H_ERRNO. 125 * 126 * Caller must parse answer and determine whether it answers the question. 127 */ 128 int 129 res_nquery(res_state statp, 130 const char *name, /* domain name */ 131 int class, int type, /* class and type of query */ 132 u_char *answer, /* buffer to put answer */ 133 int anslen) /* size of answer buffer */ 134 { 135 u_char buf[MAXPACKET]; 136 HEADER *hp = (HEADER *)(void *)answer; 137 int n; 138 u_int oflags; 139 140 oflags = statp->_flags; 141 142 again: 143 hp->rcode = NOERROR; /* default */ 144 145 #ifdef DEBUG 146 if (statp->options & RES_DEBUG) 147 printf(";; res_query(%s, %d, %d)\n", name, class, type); 148 #endif 149 150 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 151 buf, sizeof(buf)); 152 #ifdef RES_USE_EDNS0 153 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 154 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U) 155 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 156 #endif 157 if (n <= 0) { 158 #ifdef DEBUG 159 if (statp->options & RES_DEBUG) 160 printf(";; res_query: mkquery failed\n"); 161 #endif 162 RES_SET_H_ERRNO(statp, NO_RECOVERY); 163 return (n); 164 } 165 n = res_nsend(statp, buf, n, answer, anslen); 166 if (n < 0) { 167 #ifdef RES_USE_EDNS0 168 /* if the query choked with EDNS0, retry without EDNS0 */ 169 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 170 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 171 statp->_flags |= RES_F_EDNS0ERR; 172 if (statp->options & RES_DEBUG) 173 printf(";; res_nquery: retry without EDNS0\n"); 174 goto again; 175 } 176 #endif 177 #ifdef DEBUG 178 if (statp->options & RES_DEBUG) 179 printf(";; res_query: send error\n"); 180 #endif 181 RES_SET_H_ERRNO(statp, TRY_AGAIN); 182 return (n); 183 } 184 185 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 186 #ifdef DEBUG 187 if (statp->options & RES_DEBUG) 188 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 189 p_rcode(hp->rcode), 190 ntohs(hp->ancount), 191 ntohs(hp->nscount), 192 ntohs(hp->arcount)); 193 #endif 194 switch (hp->rcode) { 195 case NXDOMAIN: 196 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 197 break; 198 case SERVFAIL: 199 RES_SET_H_ERRNO(statp, TRY_AGAIN); 200 break; 201 case NOERROR: 202 RES_SET_H_ERRNO(statp, NO_DATA); 203 break; 204 case FORMERR: 205 case NOTIMP: 206 case REFUSED: 207 default: 208 RES_SET_H_ERRNO(statp, NO_RECOVERY); 209 break; 210 } 211 return (-1); 212 } 213 return (n); 214 } 215 216 /* 217 * Formulate a normal query, send, and retrieve answer in supplied buffer. 218 * Return the size of the response on success, -1 on error. 219 * If enabled, implement search rules until answer or unrecoverable failure 220 * is detected. Error code, if any, is left in H_ERRNO. 221 */ 222 int 223 res_nsearch(res_state statp, 224 const char *name, /* domain name */ 225 int class, int type, /* class and type of query */ 226 u_char *answer, /* buffer to put answer */ 227 int anslen) /* size of answer */ 228 { 229 const char *cp, * const *domain; 230 HEADER *hp = (HEADER *)(void *)answer; 231 char tmp[NS_MAXDNAME]; 232 u_int dots; 233 int trailing_dot, ret, saved_herrno; 234 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 235 int tried_as_is = 0; 236 int searched = 0; 237 238 errno = 0; 239 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ 240 241 dots = 0; 242 for (cp = name; *cp != '\0'; cp++) 243 dots += (*cp == '.'); 244 trailing_dot = 0; 245 if (cp > name && *--cp == '.') 246 trailing_dot++; 247 248 /* If there aren't any dots, it could be a user-level alias. */ 249 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 250 return (res_nquery(statp, cp, class, type, answer, anslen)); 251 252 /* 253 * If there are enough dots in the name, let's just give it a 254 * try 'as is'. The threshold can be set with the "ndots" option. 255 * Also, query 'as is', if there is a trailing dot in the name. 256 */ 257 saved_herrno = -1; 258 if (dots >= statp->ndots || trailing_dot) { 259 ret = res_nquerydomain(statp, name, NULL, class, type, 260 answer, anslen); 261 if (ret > 0 || trailing_dot) 262 return (ret); 263 saved_herrno = statp->res_h_errno; 264 tried_as_is++; 265 } 266 267 /* 268 * We do at least one level of search if 269 * - there is no dot and RES_DEFNAME is set, or 270 * - there is at least one dot, there is no trailing dot, 271 * and RES_DNSRCH is set. 272 */ 273 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 274 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 275 int done = 0; 276 277 for (domain = (const char * const *)statp->dnsrch; 278 *domain && !done; 279 domain++) { 280 searched = 1; 281 282 if (domain[0][0] == '\0' || 283 (domain[0][0] == '.' && domain[0][1] == '\0')) 284 root_on_list++; 285 286 ret = res_nquerydomain(statp, name, *domain, 287 class, type, 288 answer, anslen); 289 if (ret > 0) 290 return (ret); 291 292 /* 293 * If no server present, give up. 294 * If name isn't found in this domain, 295 * keep trying higher domains in the search list 296 * (if that's enabled). 297 * On a NO_DATA error, keep trying, otherwise 298 * a wildcard entry of another type could keep us 299 * from finding this entry higher in the domain. 300 * If we get some other error (negative answer or 301 * server failure), then stop searching up, 302 * but try the input name below in case it's 303 * fully-qualified. 304 */ 305 if (errno == ECONNREFUSED) { 306 RES_SET_H_ERRNO(statp, TRY_AGAIN); 307 return (-1); 308 } 309 310 switch (statp->res_h_errno) { 311 case NO_DATA: 312 got_nodata++; 313 /* FALLTHROUGH */ 314 case HOST_NOT_FOUND: 315 /* keep trying */ 316 break; 317 case TRY_AGAIN: 318 if (hp->rcode == SERVFAIL) { 319 /* try next search element, if any */ 320 got_servfail++; 321 break; 322 } 323 /* FALLTHROUGH */ 324 default: 325 /* anything else implies that we're done */ 326 done++; 327 } 328 329 /* if we got here for some reason other than DNSRCH, 330 * we only wanted one iteration of the loop, so stop. 331 */ 332 if ((statp->options & RES_DNSRCH) == 0U) 333 done++; 334 } 335 } 336 337 /* 338 * If the query has not already been tried as is then try it 339 * unless RES_NOTLDQUERY is set and there were no dots. 340 */ 341 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 342 !(tried_as_is || root_on_list)) { 343 ret = res_nquerydomain(statp, name, NULL, class, type, 344 answer, anslen); 345 if (ret > 0) 346 return (ret); 347 } 348 349 /* if we got here, we didn't satisfy the search. 350 * if we did an initial full query, return that query's H_ERRNO 351 * (note that we wouldn't be here if that query had succeeded). 352 * else if we ever got a nodata, send that back as the reason. 353 * else send back meaningless H_ERRNO, that being the one from 354 * the last DNSRCH we did. 355 */ 356 if (saved_herrno != -1) 357 RES_SET_H_ERRNO(statp, saved_herrno); 358 else if (got_nodata) 359 RES_SET_H_ERRNO(statp, NO_DATA); 360 else if (got_servfail) 361 RES_SET_H_ERRNO(statp, TRY_AGAIN); 362 return (-1); 363 } 364 365 /* 366 * Perform a call on res_query on the concatenation of name and domain, 367 * removing a trailing dot from name if domain is NULL. 368 */ 369 int 370 res_nquerydomain(res_state statp, 371 const char *name, 372 const char *domain, 373 int class, int type, /* class and type of query */ 374 u_char *answer, /* buffer to put answer */ 375 int anslen) /* size of answer */ 376 { 377 char nbuf[MAXDNAME]; 378 const char *longname = nbuf; 379 int n, d; 380 381 #ifdef DEBUG 382 if (statp->options & RES_DEBUG) 383 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 384 name, domain?domain:"<Nil>", class, type); 385 #endif 386 if (domain == NULL) { 387 /* 388 * Check for trailing '.'; 389 * copy without '.' if present. 390 */ 391 n = strlen(name); 392 if (n >= MAXDNAME) { 393 RES_SET_H_ERRNO(statp, NO_RECOVERY); 394 return (-1); 395 } 396 n--; 397 if (n >= 0 && name[n] == '.') { 398 strncpy(nbuf, name, (size_t)n); 399 nbuf[n] = '\0'; 400 } else 401 longname = name; 402 } else { 403 n = strlen(name); 404 d = strlen(domain); 405 if (n + d + 1 >= MAXDNAME) { 406 RES_SET_H_ERRNO(statp, NO_RECOVERY); 407 return (-1); 408 } 409 sprintf(nbuf, "%s.%s", name, domain); 410 } 411 return (res_nquery(statp, longname, class, type, answer, anslen)); 412 } 413 414 const char * 415 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 416 char *file, *cp1, *cp2; 417 char buf[BUFSIZ]; 418 FILE *fp; 419 420 if (statp->options & RES_NOALIASES) 421 return (NULL); 422 file = getenv("HOSTALIASES"); 423 if (file == NULL || (fp = fopen(file, "r")) == NULL) 424 return (NULL); 425 setbuf(fp, NULL); 426 buf[sizeof(buf) - 1] = '\0'; 427 while (fgets(buf, sizeof(buf), fp)) { 428 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 429 ; 430 if (!*cp1) 431 break; 432 *cp1 = '\0'; 433 if (ns_samename(buf, name) == 1) { 434 while (isspace((unsigned char)*++cp1)) 435 ; 436 if (!*cp1) 437 break; 438 for (cp2 = cp1 + 1; *cp2 && 439 !isspace((unsigned char)*cp2); ++cp2) 440 ; 441 *cp2 = '\0'; 442 strncpy(dst, cp1, siz - 1); 443 dst[siz - 1] = '\0'; 444 fclose(fp); 445 return (dst); 446 } 447 } 448 fclose(fp); 449 return (NULL); 450 } 451