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 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 */ 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 int n; 120 u_int oflags; 121 122 oflags = statp->_flags; 123 124 again: 125 hp->rcode = NOERROR; /* default */ 126 127 #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)) != 0U) 137 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 138 #endif 139 if (n <= 0) { 140 #ifdef DEBUG 141 if (statp->options & RES_DEBUG) 142 printf(";; res_query: mkquery failed\n"); 143 #endif 144 RES_SET_H_ERRNO(statp, NO_RECOVERY); 145 return (n); 146 } 147 n = res_nsend(statp, buf, n, answer, anslen); 148 if (n < 0) { 149 #ifdef RES_USE_EDNS0 150 /* if the query choked with EDNS0, retry without EDNS0 */ 151 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 152 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 153 statp->_flags |= RES_F_EDNS0ERR; 154 if (statp->options & RES_DEBUG) 155 printf(";; res_nquery: retry without EDNS0\n"); 156 goto again; 157 } 158 #endif 159 #ifdef DEBUG 160 if (statp->options & RES_DEBUG) 161 printf(";; res_query: send error\n"); 162 #endif 163 RES_SET_H_ERRNO(statp, TRY_AGAIN); 164 return (n); 165 } 166 167 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 168 #ifdef DEBUG 169 if (statp->options & RES_DEBUG) 170 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 171 p_rcode(hp->rcode), 172 ntohs(hp->ancount), 173 ntohs(hp->nscount), 174 ntohs(hp->arcount)); 175 #endif 176 switch (hp->rcode) { 177 case NXDOMAIN: 178 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 179 break; 180 case SERVFAIL: 181 RES_SET_H_ERRNO(statp, TRY_AGAIN); 182 break; 183 case NOERROR: 184 RES_SET_H_ERRNO(statp, NO_DATA); 185 break; 186 case FORMERR: 187 case NOTIMP: 188 case REFUSED: 189 default: 190 RES_SET_H_ERRNO(statp, NO_RECOVERY); 191 break; 192 } 193 return (-1); 194 } 195 return (n); 196 } 197 198 /* 199 * Formulate a normal query, send, and retrieve answer in supplied buffer. 200 * Return the size of the response on success, -1 on error. 201 * If enabled, implement search rules until answer or unrecoverable failure 202 * is detected. Error code, if any, is left in H_ERRNO. 203 */ 204 int 205 res_nsearch(res_state statp, 206 const char *name, /* domain name */ 207 int class, int type, /* class and type of query */ 208 u_char *answer, /* buffer to put answer */ 209 int anslen) /* size of answer */ 210 { 211 const char *cp, * const *domain; 212 HEADER *hp = (HEADER *) answer; 213 char tmp[NS_MAXDNAME]; 214 u_int dots; 215 int trailing_dot, ret, saved_herrno; 216 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 217 int tried_as_is = 0; 218 int searched = 0; 219 220 errno = 0; 221 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ 222 223 dots = 0; 224 for (cp = name; *cp != '\0'; cp++) 225 dots += (*cp == '.'); 226 trailing_dot = 0; 227 if (cp > name && *--cp == '.') 228 trailing_dot++; 229 230 /* If there aren't any dots, it could be a user-level alias. */ 231 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 232 return (res_nquery(statp, cp, class, type, answer, anslen)); 233 234 /* 235 * If there are enough dots in the name, let's just give it a 236 * try 'as is'. The threshold can be set with the "ndots" option. 237 * Also, query 'as is', if there is a trailing dot in the name. 238 */ 239 saved_herrno = -1; 240 if (dots >= statp->ndots || trailing_dot) { 241 ret = res_nquerydomain(statp, name, NULL, class, type, 242 answer, anslen); 243 if (ret > 0 || trailing_dot) 244 return (ret); 245 saved_herrno = statp->res_h_errno; 246 tried_as_is++; 247 } 248 249 /* 250 * We do at least one level of search if 251 * - there is no dot and RES_DEFNAME is set, or 252 * - there is at least one dot, there is no trailing dot, 253 * and RES_DNSRCH is set. 254 */ 255 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 256 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 257 int done = 0; 258 259 for (domain = (const char * const *)statp->dnsrch; 260 *domain && !done; 261 domain++) { 262 searched = 1; 263 264 if (domain[0][0] == '\0' || 265 (domain[0][0] == '.' && domain[0][1] == '\0')) 266 root_on_list++; 267 268 ret = res_nquerydomain(statp, name, *domain, 269 class, type, 270 answer, anslen); 271 if (ret > 0) 272 return (ret); 273 274 /* 275 * If no server present, give up. 276 * If name isn't found in this domain, 277 * keep trying higher domains in the search list 278 * (if that's enabled). 279 * On a NO_DATA error, keep trying, otherwise 280 * a wildcard entry of another type could keep us 281 * from finding this entry higher in the domain. 282 * If we get some other error (negative answer or 283 * server failure), then stop searching up, 284 * but try the input name below in case it's 285 * fully-qualified. 286 */ 287 if (errno == ECONNREFUSED) { 288 RES_SET_H_ERRNO(statp, TRY_AGAIN); 289 return (-1); 290 } 291 292 switch (statp->res_h_errno) { 293 case NO_DATA: 294 got_nodata++; 295 /* FALLTHROUGH */ 296 case HOST_NOT_FOUND: 297 /* keep trying */ 298 break; 299 case TRY_AGAIN: 300 if (hp->rcode == SERVFAIL) { 301 /* try next search element, if any */ 302 got_servfail++; 303 break; 304 } 305 /* FALLTHROUGH */ 306 default: 307 /* anything else implies that we're done */ 308 done++; 309 } 310 311 /* if we got here for some reason other than DNSRCH, 312 * we only wanted one iteration of the loop, so stop. 313 */ 314 if ((statp->options & RES_DNSRCH) == 0U) 315 done++; 316 } 317 } 318 319 /* 320 * If the query has not already been tried as is then try it 321 * unless RES_NOTLDQUERY is set and there were no dots. 322 */ 323 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 324 !(tried_as_is || root_on_list)) { 325 ret = res_nquerydomain(statp, name, NULL, class, type, 326 answer, anslen); 327 if (ret > 0) 328 return (ret); 329 } 330 331 /* if we got here, we didn't satisfy the search. 332 * if we did an initial full query, return that query's H_ERRNO 333 * (note that we wouldn't be here if that query had succeeded). 334 * else if we ever got a nodata, send that back as the reason. 335 * else send back meaningless H_ERRNO, that being the one from 336 * the last DNSRCH we did. 337 */ 338 if (saved_herrno != -1) 339 RES_SET_H_ERRNO(statp, saved_herrno); 340 else if (got_nodata) 341 RES_SET_H_ERRNO(statp, NO_DATA); 342 else if (got_servfail) 343 RES_SET_H_ERRNO(statp, TRY_AGAIN); 344 return (-1); 345 } 346 347 /* 348 * Perform a call on res_query on the concatenation of name and domain, 349 * removing a trailing dot from name if domain is NULL. 350 */ 351 int 352 res_nquerydomain(res_state statp, 353 const char *name, 354 const char *domain, 355 int class, int type, /* class and type of query */ 356 u_char *answer, /* buffer to put answer */ 357 int anslen) /* size of answer */ 358 { 359 char nbuf[MAXDNAME]; 360 const char *longname = nbuf; 361 int n, d; 362 363 #ifdef DEBUG 364 if (statp->options & RES_DEBUG) 365 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 366 name, domain?domain:"<Nil>", class, type); 367 #endif 368 if (domain == NULL) { 369 /* 370 * Check for trailing '.'; 371 * copy without '.' if present. 372 */ 373 n = strlen(name); 374 if (n >= MAXDNAME) { 375 RES_SET_H_ERRNO(statp, NO_RECOVERY); 376 return (-1); 377 } 378 n--; 379 if (n >= 0 && name[n] == '.') { 380 strncpy(nbuf, name, n); 381 nbuf[n] = '\0'; 382 } else 383 longname = name; 384 } else { 385 n = strlen(name); 386 d = strlen(domain); 387 if (n + d + 1 >= MAXDNAME) { 388 RES_SET_H_ERRNO(statp, NO_RECOVERY); 389 return (-1); 390 } 391 sprintf(nbuf, "%s.%s", name, domain); 392 } 393 return (res_nquery(statp, longname, class, type, answer, anslen)); 394 } 395 396 const char * 397 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 398 char *file, *cp1, *cp2; 399 char buf[BUFSIZ]; 400 FILE *fp; 401 402 if (statp->options & RES_NOALIASES) 403 return (NULL); 404 file = getenv("HOSTALIASES"); 405 if (file == NULL || (fp = fopen(file, "r")) == NULL) 406 return (NULL); 407 setbuf(fp, NULL); 408 buf[sizeof(buf) - 1] = '\0'; 409 while (fgets(buf, sizeof(buf), fp)) { 410 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 411 ; 412 if (!*cp1) 413 break; 414 *cp1 = '\0'; 415 if (ns_samename(buf, name) == 1) { 416 while (isspace((unsigned char)*++cp1)) 417 ; 418 if (!*cp1) 419 break; 420 for (cp2 = cp1 + 1; *cp2 && 421 !isspace((unsigned char)*cp2); ++cp2) 422 ; 423 *cp2 = '\0'; 424 strncpy(dst, cp1, siz - 1); 425 dst[siz - 1] = '\0'; 426 fclose(fp); 427 return (dst); 428 } 429 } 430 fclose(fp); 431 return (NULL); 432 } 433