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 #include "port_before.h" 72 #include <sys/types.h> 73 #include <sys/param.h> 74 #include <netinet/in.h> 75 #include <arpa/inet.h> 76 #include <arpa/nameser.h> 77 #include <ctype.h> 78 #include <errno.h> 79 #include <netdb.h> 80 #include <resolv.h> 81 #include <stdio.h> 82 #include <stdlib.h> 83 #include <string.h> 84 #include "port_after.h" 85 86 /* Options. Leave them on. */ 87 #define DEBUG 88 89 #if PACKETSZ > 1024 90 #define MAXPACKET PACKETSZ 91 #else 92 #define MAXPACKET 1024 93 #endif 94 95 /*% 96 * Formulate a normal query, send, and await answer. 97 * Returned answer is placed in supplied buffer "answer". 98 * Perform preliminary check of answer, returning success only 99 * if no error is indicated and the answer count is nonzero. 100 * Return the size of the response on success, -1 on error. 101 * Error number is left in H_ERRNO. 102 * 103 * Caller must parse answer and determine whether it answers the question. 104 */ 105 int 106 res_nquery(res_state statp, 107 const char *name, /*%< domain name */ 108 int class, int type, /*%< class and type of query */ 109 u_char *answer, /*%< buffer to put answer */ 110 int anslen) /*%< size of answer buffer */ 111 { 112 u_char buf[MAXPACKET]; 113 HEADER *hp = (HEADER *) answer; 114 u_int oflags; 115 u_char *rdata; 116 int n; 117 118 oflags = statp->_flags; 119 120 again: 121 hp->rcode = NOERROR; /*%< default */ 122 #ifdef DEBUG 123 if (statp->options & RES_DEBUG) 124 printf(";; res_query(%s, %d, %d)\n", name, class, type); 125 #endif 126 127 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 128 buf, sizeof(buf)); 129 #ifdef RES_USE_EDNS0 130 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 131 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) { 132 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 133 rdata = &buf[n]; 134 if (n > 0 && (statp->options & RES_NSID) != 0U) { 135 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 136 NS_OPT_NSID, 0, NULL); 137 } 138 } 139 #endif 140 if (n <= 0) { 141 #ifdef DEBUG 142 if (statp->options & RES_DEBUG) 143 printf(";; res_query: mkquery failed\n"); 144 #endif 145 RES_SET_H_ERRNO(statp, NO_RECOVERY); 146 return (n); 147 } 148 149 n = res_nsend(statp, buf, n, answer, anslen); 150 if (n < 0) { 151 #ifdef RES_USE_EDNS0 152 /* if the query choked with EDNS0, retry without EDNS0 */ 153 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 154 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 155 statp->_flags |= RES_F_EDNS0ERR; 156 if (statp->options & RES_DEBUG) 157 printf(";; res_nquery: retry without EDNS0\n"); 158 goto again; 159 } 160 #endif 161 #ifdef DEBUG 162 if (statp->options & RES_DEBUG) 163 printf(";; res_query: send error\n"); 164 #endif 165 RES_SET_H_ERRNO(statp, TRY_AGAIN); 166 return (n); 167 } 168 169 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 170 #ifdef DEBUG 171 if (statp->options & RES_DEBUG) 172 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 173 p_rcode(hp->rcode), 174 ntohs(hp->ancount), 175 ntohs(hp->nscount), 176 ntohs(hp->arcount)); 177 #endif 178 switch (hp->rcode) { 179 case NXDOMAIN: 180 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 181 break; 182 case SERVFAIL: 183 RES_SET_H_ERRNO(statp, TRY_AGAIN); 184 break; 185 case NOERROR: 186 RES_SET_H_ERRNO(statp, NO_DATA); 187 break; 188 case FORMERR: 189 case NOTIMP: 190 case REFUSED: 191 default: 192 RES_SET_H_ERRNO(statp, NO_RECOVERY); 193 break; 194 } 195 return (-1); 196 } 197 return (n); 198 } 199 200 /*% 201 * Formulate a normal query, send, and retrieve answer in supplied buffer. 202 * Return the size of the response on success, -1 on error. 203 * If enabled, implement search rules until answer or unrecoverable failure 204 * is detected. Error code, if any, is left in H_ERRNO. 205 */ 206 int 207 res_nsearch(res_state statp, 208 const char *name, /*%< domain name */ 209 int class, int type, /*%< class and type of query */ 210 u_char *answer, /*%< buffer to put answer */ 211 int anslen) /*%< size of answer */ 212 { 213 const char *cp, * const *domain; 214 HEADER *hp = (HEADER *) answer; 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 dots = 0; 225 for (cp = name; *cp != '\0'; cp++) 226 dots += (*cp == '.'); 227 trailing_dot = 0; 228 if (cp > name && *--cp == '.') 229 trailing_dot++; 230 231 /* If there aren't any dots, it could be a user-level alias. */ 232 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 233 return (res_nquery(statp, cp, class, type, answer, anslen)); 234 235 /* 236 * If there are enough dots in the name, let's just give it a 237 * try 'as is'. The threshold can be set with the "ndots" option. 238 * Also, query 'as is', if there is a trailing dot in the name. 239 */ 240 saved_herrno = -1; 241 if (dots >= statp->ndots || trailing_dot) { 242 ret = res_nquerydomain(statp, name, NULL, class, type, 243 answer, anslen); 244 if (ret > 0 || trailing_dot) 245 return (ret); 246 saved_herrno = statp->res_h_errno; 247 tried_as_is++; 248 } 249 250 /* 251 * We do at least one level of search if 252 * - there is no dot and RES_DEFNAME is set, or 253 * - there is at least one dot, there is no trailing dot, 254 * and RES_DNSRCH is set. 255 */ 256 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 257 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 258 int done = 0; 259 260 for (domain = (const char * const *)statp->dnsrch; 261 *domain && !done; 262 domain++) { 263 searched = 1; 264 265 if (domain[0][0] == '\0' || 266 (domain[0][0] == '.' && domain[0][1] == '\0')) 267 root_on_list++; 268 269 ret = res_nquerydomain(statp, name, *domain, 270 class, type, 271 answer, anslen); 272 if (ret > 0) 273 return (ret); 274 275 /* 276 * If no server present, give up. 277 * If name isn't found in this domain, 278 * keep trying higher domains in the search list 279 * (if that's enabled). 280 * On a NO_DATA error, keep trying, otherwise 281 * a wildcard entry of another type could keep us 282 * from finding this entry higher in the domain. 283 * If we get some other error (negative answer or 284 * server failure), then stop searching up, 285 * but try the input name below in case it's 286 * fully-qualified. 287 */ 288 if (errno == ECONNREFUSED) { 289 RES_SET_H_ERRNO(statp, TRY_AGAIN); 290 return (-1); 291 } 292 293 switch (statp->res_h_errno) { 294 case NO_DATA: 295 got_nodata++; 296 /* FALLTHROUGH */ 297 case HOST_NOT_FOUND: 298 /* keep trying */ 299 break; 300 case TRY_AGAIN: 301 if (hp->rcode == SERVFAIL) { 302 /* try next search element, if any */ 303 got_servfail++; 304 break; 305 } 306 /* FALLTHROUGH */ 307 default: 308 /* anything else implies that we're done */ 309 done++; 310 } 311 312 /* if we got here for some reason other than DNSRCH, 313 * we only wanted one iteration of the loop, so stop. 314 */ 315 if ((statp->options & RES_DNSRCH) == 0U) 316 done++; 317 } 318 } 319 320 /* 321 * If the query has not already been tried as is then try it 322 * unless RES_NOTLDQUERY is set and there were no dots. 323 */ 324 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 325 !(tried_as_is || root_on_list)) { 326 ret = res_nquerydomain(statp, name, NULL, class, type, 327 answer, anslen); 328 if (ret > 0) 329 return (ret); 330 } 331 332 /* if we got here, we didn't satisfy the search. 333 * if we did an initial full query, return that query's H_ERRNO 334 * (note that we wouldn't be here if that query had succeeded). 335 * else if we ever got a nodata, send that back as the reason. 336 * else send back meaningless H_ERRNO, that being the one from 337 * the last DNSRCH we did. 338 */ 339 if (saved_herrno != -1) 340 RES_SET_H_ERRNO(statp, saved_herrno); 341 else if (got_nodata) 342 RES_SET_H_ERRNO(statp, NO_DATA); 343 else if (got_servfail) 344 RES_SET_H_ERRNO(statp, TRY_AGAIN); 345 return (-1); 346 } 347 348 /*% 349 * Perform a call on res_query on the concatenation of name and domain, 350 * removing a trailing dot from name if domain is NULL. 351 */ 352 int 353 res_nquerydomain(res_state statp, 354 const char *name, 355 const char *domain, 356 int class, int type, /*%< class and type of query */ 357 u_char *answer, /*%< buffer to put answer */ 358 int anslen) /*%< size of answer */ 359 { 360 char nbuf[MAXDNAME]; 361 const char *longname = nbuf; 362 int n, d; 363 364 #ifdef DEBUG 365 if (statp->options & RES_DEBUG) 366 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 367 name, domain?domain:"<Nil>", class, type); 368 #endif 369 if (domain == NULL) { 370 /* 371 * Check for trailing '.'; 372 * copy without '.' if present. 373 */ 374 n = strlen(name); 375 if (n >= MAXDNAME) { 376 RES_SET_H_ERRNO(statp, NO_RECOVERY); 377 return (-1); 378 } 379 n--; 380 if (n >= 0 && name[n] == '.') { 381 strncpy(nbuf, name, n); 382 nbuf[n] = '\0'; 383 } else 384 longname = name; 385 } else { 386 n = strlen(name); 387 d = strlen(domain); 388 if (n + d + 1 >= MAXDNAME) { 389 RES_SET_H_ERRNO(statp, NO_RECOVERY); 390 return (-1); 391 } 392 sprintf(nbuf, "%s.%s", name, domain); 393 } 394 return (res_nquery(statp, longname, class, type, answer, anslen)); 395 } 396 397 const char * 398 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 399 char *file, *cp1, *cp2; 400 char buf[BUFSIZ]; 401 FILE *fp; 402 403 if (statp->options & RES_NOALIASES) 404 return (NULL); 405 file = getenv("HOSTALIASES"); 406 if (file == NULL || (fp = fopen(file, "r")) == NULL) 407 return (NULL); 408 setbuf(fp, NULL); 409 buf[sizeof(buf) - 1] = '\0'; 410 while (fgets(buf, sizeof(buf), fp)) { 411 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 412 ; 413 if (!*cp1) 414 break; 415 *cp1 = '\0'; 416 if (ns_samename(buf, name) == 1) { 417 while (isspace((unsigned char)*++cp1)) 418 ; 419 if (!*cp1) 420 break; 421 for (cp2 = cp1 + 1; *cp2 && 422 !isspace((unsigned char)*cp2); ++cp2) 423 ; 424 *cp2 = '\0'; 425 strncpy(dst, cp1, siz - 1); 426 dst[siz - 1] = '\0'; 427 fclose(fp); 428 return (dst); 429 } 430 } 431 fclose(fp); 432 return (NULL); 433 } 434 435 /*! \file */ 436