1 /* 2 * Copyright (c) 1988, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Portions copyright (c) 1999, 2000 6 * Intel Corporation. 7 * All rights reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * 3. All advertising materials mentioning features or use of this software 21 * must display the following acknowledgement: 22 * 23 * This product includes software developed by the University of 24 * California, Berkeley, Intel Corporation, and its contributors. 25 * 26 * 4. Neither the name of University, Intel Corporation, or their respective 27 * contributors may be used to endorse or promote products derived from 28 * this software without specific prior written permission. 29 * 30 * THIS SOFTWARE IS PROVIDED BY THE REGENTS, INTEL CORPORATION AND 31 * CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, 32 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 33 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS, 34 * INTEL CORPORATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 35 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 36 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 37 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 38 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 39 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 40 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 41 * 42 */ 43 44 /* 45 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 46 * 47 * Permission to use, copy, modify, and distribute this software for any 48 * purpose with or without fee is hereby granted, provided that the above 49 * copyright notice and this permission notice appear in all copies, and that 50 * the name of Digital Equipment Corporation not be used in advertising or 51 * publicity pertaining to distribution of the document or software without 52 * specific, written prior permission. 53 * 54 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 55 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 56 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 57 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 58 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 59 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 60 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 61 * SOFTWARE. 62 */ 63 64 /* 65 * Portions Copyright (c) 1996 by Internet Software Consortium. 66 * 67 * Permission to use, copy, modify, and distribute this software for any 68 * purpose with or without fee is hereby granted, provided that the above 69 * copyright notice and this permission notice appear in all copies. 70 * 71 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS 72 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES 73 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE 74 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 75 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 76 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 77 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 78 * SOFTWARE. 79 */ 80 81 #if defined(LIBC_SCCS) && !defined(lint) 82 static char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 83 static char orig_rcsid = "From: Id: res_query.c,v 8.14 1997/06/09 17:47:05 halley Exp $"; 84 static char rcsid[] = "$Id: res_query.c,v 1.1.1.1 2003/11/19 01:51:38 kyu3 Exp $"; 85 #endif /* LIBC_SCCS and not lint */ 86 87 #include <sys/types.h> 88 #include <sys/param.h> 89 #include <netinet/in.h> 90 #include <arpa/inet.h> 91 #include <arpa/nameser.h> 92 #include <ctype.h> 93 #include <errno.h> 94 #include <netdb.h> 95 #include <resolv.h> 96 #include <stdio.h> 97 #include <stdlib.h> 98 #include <string.h> 99 100 #include "res_config.h" 101 102 #if PACKETSZ > 1024 103 #define MAXPACKET PACKETSZ 104 #else 105 #define MAXPACKET 1024 106 #endif 107 108 /* 109 * Formulate a normal query, send, and await answer. 110 * Returned answer is placed in supplied buffer "answer". 111 * Perform preliminary check of answer, returning success only 112 * if no error is indicated and the answer count is nonzero. 113 * Return the size of the response on success, -1 on error. 114 * Error number is left in h_errno. 115 * 116 * Caller must parse answer and determine whether it answers the question. 117 */ 118 int 119 res_query( 120 const char *name, /* domain name */ 121 int class, /* class of query */ 122 int type, /* type of query */ 123 u_char *answer, /* buffer to put answer */ 124 int anslen /* size of answer buffer */ 125 ) 126 { 127 u_char buf[MAXPACKET]; 128 HEADER *hp = (HEADER *) answer; 129 int n; 130 131 hp->rcode = NOERROR; /* default */ 132 133 if ((_res.options & RES_INIT) == 0 && res_init() == -1) { 134 h_errno = NETDB_INTERNAL; 135 return (-1); 136 } 137 #ifdef DEBUG 138 if (_res.options & RES_DEBUG) 139 printf(";; res_query(%s, %d, %d)\n", name, class, type); 140 #endif 141 142 n = res_mkquery(QUERY, name, class, type, NULL, 0, NULL, 143 buf, sizeof(buf)); 144 if (n <= 0) { 145 #ifdef DEBUG 146 if (_res.options & RES_DEBUG) 147 printf(";; res_query: mkquery failed\n"); 148 #endif 149 h_errno = NO_RECOVERY; 150 return (n); 151 } 152 n = res_send(buf, n, answer, anslen); 153 if (n < 0) { 154 #ifdef DEBUG 155 if (_res.options & RES_DEBUG) 156 printf(";; res_query: send error\n"); 157 #endif 158 h_errno = TRY_AGAIN; 159 return (n); 160 } 161 162 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 163 #ifdef DEBUG 164 if (_res.options & RES_DEBUG) 165 printf(";; rcode = %d, ancount=%d\n", hp->rcode, 166 ntohs(hp->ancount)); 167 #endif 168 switch (hp->rcode) { 169 case NXDOMAIN: 170 h_errno = HOST_NOT_FOUND; 171 break; 172 case SERVFAIL: 173 h_errno = TRY_AGAIN; 174 break; 175 case NOERROR: 176 h_errno = NO_DATA; 177 break; 178 case FORMERR: 179 case NOTIMP: 180 case REFUSED: 181 default: 182 h_errno = NO_RECOVERY; 183 break; 184 } 185 return (-1); 186 } 187 return (n); 188 } 189 190 /* 191 * Formulate a normal query, send, and retrieve answer in supplied buffer. 192 * Return the size of the response on success, -1 on error. 193 * If enabled, implement search rules until answer or unrecoverable failure 194 * is detected. Error code, if any, is left in h_errno. 195 */ 196 int 197 res_search( 198 const char *name, /* domain name */ 199 int class, /* class of query */ 200 int type, /* type of query */ 201 u_char *answer, /* buffer to put answer */ 202 int anslen /* size of answer */ 203 ) 204 { 205 const char *cp, * const *domain; 206 HEADER *hp = (HEADER *) answer; 207 u_int dots; 208 int trailing_dot, ret, saved_herrno; 209 int got_nodata = 0, got_servfail = 0, tried_as_is = 0; 210 211 if ((_res.options & RES_INIT) == 0 && res_init() == -1) { 212 h_errno = NETDB_INTERNAL; 213 return (-1); 214 } 215 errno = 0; 216 h_errno = HOST_NOT_FOUND; /* default, if we never query */ 217 dots = 0; 218 for (cp = name; *cp; cp++) 219 dots += (*cp == '.'); 220 trailing_dot = 0; 221 if (cp > name && *--cp == '.') 222 trailing_dot++; 223 224 /* If there aren't any dots, it could be a user-level alias */ 225 if (!dots && (cp = hostalias(name)) != NULL) 226 return (res_query(cp, class, type, answer, anslen)); 227 228 /* 229 * If there are dots in the name already, let's just give it a try 230 * 'as is'. The threshold can be set with the "ndots" option. 231 */ 232 saved_herrno = -1; 233 if (dots >= _res.ndots) { 234 ret = res_querydomain(name, NULL, class, type, answer, anslen); 235 if (ret > 0) 236 return (ret); 237 saved_herrno = h_errno; 238 tried_as_is++; 239 } 240 241 /* 242 * We do at least one level of search if 243 * - there is no dot and RES_DEFNAME is set, or 244 * - there is at least one dot, there is no trailing dot, 245 * and RES_DNSRCH is set. 246 */ 247 if ((!dots && (_res.options & RES_DEFNAMES)) || 248 (dots && !trailing_dot && (_res.options & RES_DNSRCH))) { 249 int done = 0; 250 251 for (domain = (const char * const *)_res.dnsrch; 252 *domain && !done; 253 domain++) { 254 255 ret = res_querydomain(name, *domain, class, type, 256 answer, anslen); 257 if (ret > 0) 258 return (ret); 259 260 /* 261 * If no server present, give up. 262 * If name isn't found in this domain, 263 * keep trying higher domains in the search list 264 * (if that's enabled). 265 * On a NO_DATA error, keep trying, otherwise 266 * a wildcard entry of another type could keep us 267 * from finding this entry higher in the domain. 268 * If we get some other error (negative answer or 269 * server failure), then stop searching up, 270 * but try the input name below in case it's 271 * fully-qualified. 272 */ 273 if (errno == ECONNREFUSED) { 274 h_errno = TRY_AGAIN; 275 return (-1); 276 } 277 278 switch (h_errno) { 279 case NO_DATA: 280 got_nodata++; 281 /* FALLTHROUGH */ 282 case HOST_NOT_FOUND: 283 /* keep trying */ 284 break; 285 case TRY_AGAIN: 286 if (hp->rcode == SERVFAIL) { 287 /* try next search element, if any */ 288 got_servfail++; 289 break; 290 } 291 /* FALLTHROUGH */ 292 default: 293 /* anything else implies that we're done */ 294 done++; 295 } 296 297 /* if we got here for some reason other than DNSRCH, 298 * we only wanted one iteration of the loop, so stop. 299 */ 300 if (!(_res.options & RES_DNSRCH)) 301 done++; 302 } 303 } 304 305 /* 306 * If we have not already tried the name "as is", do that now. 307 * note that we do this regardless of how many dots were in the 308 * name or whether it ends with a dot unless NOTLDQUERY is set. 309 */ 310 if (!tried_as_is && (dots || !(_res.options & RES_NOTLDQUERY))) { 311 ret = res_querydomain(name, NULL, class, type, answer, anslen); 312 if (ret > 0) 313 return (ret); 314 } 315 316 /* if we got here, we didn't satisfy the search. 317 * if we did an initial full query, return that query's h_errno 318 * (note that we wouldn't be here if that query had succeeded). 319 * else if we ever got a nodata, send that back as the reason. 320 * else send back meaningless h_errno, that being the one from 321 * the last DNSRCH we did. 322 */ 323 if (saved_herrno != -1) 324 h_errno = saved_herrno; 325 else if (got_nodata) 326 h_errno = NO_DATA; 327 else if (got_servfail) 328 h_errno = TRY_AGAIN; 329 return (-1); 330 } 331 332 /* 333 * Perform a call on res_query on the concatenation of name and domain, 334 * removing a trailing dot from name if domain is NULL. 335 */ 336 int 337 res_querydomain( 338 const char *name, 339 const char *domain, 340 int class, /* class of query */ 341 int type, /* type of query */ 342 u_char *answer, /* buffer to put answer */ 343 int anslen /* size of answer */ 344 ) 345 { 346 char nbuf[MAXDNAME]; 347 const char *longname = nbuf; 348 int n, d; 349 350 if ((_res.options & RES_INIT) == 0 && res_init() == -1) { 351 h_errno = NETDB_INTERNAL; 352 return (-1); 353 } 354 #ifdef DEBUG 355 if (_res.options & RES_DEBUG) 356 printf(";; res_querydomain(%s, %s, %d, %d)\n", 357 name, domain?domain:"<Nil>", class, type); 358 #endif 359 if (domain == NULL) { 360 /* 361 * Check for trailing '.'; 362 * copy without '.' if present. 363 */ 364 n = (int)strlen(name); 365 if (n >= MAXDNAME) { 366 h_errno = NO_RECOVERY; 367 return (-1); 368 } 369 n--; 370 if (n >= 0 && name[n] == '.') { 371 strncpy(nbuf, name, n); 372 nbuf[n] = '\0'; 373 } else 374 longname = name; 375 } else { 376 n = (int)strlen(name); 377 d = (int)strlen(domain); 378 if (n + d + 1 >= MAXDNAME) { 379 h_errno = NO_RECOVERY; 380 return (-1); 381 } 382 sprintf(nbuf, "%s.%s", name, domain); 383 } 384 return (res_query(longname, class, type, answer, anslen)); 385 } 386 387 const char * 388 hostalias( 389 const char *name 390 ) 391 { 392 register char *cp1, *cp2; 393 FILE *fp; 394 char *file; 395 char buf[BUFSIZ]; 396 static char abuf[MAXDNAME]; 397 398 if (_res.options & RES_NOALIASES) 399 return (NULL); 400 #ifdef _ORG_FREEBSD_ 401 if (issetugid()) 402 return (NULL); 403 #endif 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(*cp1); ++cp1) 411 ; 412 if (!*cp1) 413 break; 414 *cp1 = '\0'; 415 if (!strcasecmp(buf, name)) { 416 while (isspace(*++cp1)) 417 ; 418 if (!*cp1) 419 break; 420 for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2) 421 ; 422 abuf[sizeof(abuf) - 1] = *cp2 = '\0'; 423 strncpy(abuf, cp1, sizeof(abuf) - 1); 424 fclose(fp); 425 return (abuf); 426 } 427 } 428 fclose(fp); 429 return (NULL); 430 } 431
