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Annotation of src/lib/libc/resolv/res_query.c, Revision 1.11.14.1

1.11.14.1! riz         1: /*     $NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $  */
        !             2:
        !             3: /*
        !             4:  * Portions Copyright (C) 2004, 2005, 2008  Internet Systems Consortium, Inc. ("ISC")
        !             5:  * Portions Copyright (C) 1996-2001, 2003  Internet Software Consortium.
        !             6:  *
        !             7:  * Permission to use, copy, modify, and/or distribute this software for any
        !             8:  * purpose with or without fee is hereby granted, provided that the above
        !             9:  * copyright notice and this permission notice appear in all copies.
        !            10:  *
        !            11:  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
        !            12:  * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
        !            13:  * AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
        !            14:  * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
        !            15:  * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
        !            16:  * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
        !            17:  * PERFORMANCE OF THIS SOFTWARE.
        !            18:  */
1.1       christos   19:
                     20: /*
                     21:  * Copyright (c) 1988, 1993
                     22:  *    The Regents of the University of California.  All rights reserved.
1.11.14.1! riz        23:  *
1.1       christos   24:  * Redistribution and use in source and binary forms, with or without
                     25:  * modification, are permitted provided that the following conditions
                     26:  * are met:
                     27:  * 1. Redistributions of source code must retain the above copyright
                     28:  *    notice, this list of conditions and the following disclaimer.
                     29:  * 2. Redistributions in binary form must reproduce the above copyright
                     30:  *    notice, this list of conditions and the following disclaimer in the
                     31:  *    documentation and/or other materials provided with the distribution.
                     32:  * 3. All advertising materials mentioning features or use of this software
                     33:  *    must display the following acknowledgement:
                     34:  *     This product includes software developed by the University of
                     35:  *     California, Berkeley and its contributors.
                     36:  * 4. Neither the name of the University nor the names of its contributors
                     37:  *    may be used to endorse or promote products derived from this software
                     38:  *    without specific prior written permission.
1.11.14.1! riz        39:  *
1.1       christos   40:  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
                     41:  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
                     42:  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
                     43:  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
                     44:  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
                     45:  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
                     46:  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
                     47:  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
                     48:  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
                     49:  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
                     50:  * SUCH DAMAGE.
                     51:  */
                     52:
                     53: /*
                     54:  * Portions Copyright (c) 1993 by Digital Equipment Corporation.
1.11.14.1! riz        55:  *
1.1       christos   56:  * Permission to use, copy, modify, and distribute this software for any
                     57:  * purpose with or without fee is hereby granted, provided that the above
                     58:  * copyright notice and this permission notice appear in all copies, and that
                     59:  * the name of Digital Equipment Corporation not be used in advertising or
                     60:  * publicity pertaining to distribution of the document or software without
                     61:  * specific, written prior permission.
1.11.14.1! riz        62:  *
1.1       christos   63:  * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL
                     64:  * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES
                     65:  * OF MERCHANTABILITY AND FITNESS.   IN NO EVENT SHALL DIGITAL EQUIPMENT
                     66:  * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
                     67:  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
                     68:  * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
                     69:  * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
                     70:  * SOFTWARE.
                     71:  */
                     72:
                     73: /*
                     74:  * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
                     75:  * Portions Copyright (c) 1996-1999 by Internet Software Consortium.
                     76:  *
                     77:  * Permission to use, copy, modify, and distribute this software for any
                     78:  * purpose with or without fee is hereby granted, provided that the above
                     79:  * copyright notice and this permission notice appear in all copies.
                     80:  *
                     81:  * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
                     82:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
                     83:  * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
                     84:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
                     85:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
                     86:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
                     87:  * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
                     88:  */
                     89:
1.3       christos   90: #include <sys/cdefs.h>
1.1       christos   91: #if defined(LIBC_SCCS) && !defined(lint)
1.3       christos   92: #ifdef notdef
1.1       christos   93: static const char sccsid[] = "@(#)res_query.c  8.1 (Berkeley) 6/4/93";
1.11.14.1! riz        94: static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp";
1.3       christos   95: #else
1.11.14.1! riz        96: __RCSID("$NetBSD: res_query.c,v 1.13 2009/10/24 21:37:57 christos Exp $");
1.3       christos   97: #endif
1.1       christos   98: #endif /* LIBC_SCCS and not lint */
                     99:
                    100: #include "port_before.h"
1.4       christos  101:
                    102: #include "namespace.h"
1.1       christos  103: #include <sys/types.h>
                    104: #include <sys/param.h>
                    105: #include <netinet/in.h>
                    106: #include <arpa/inet.h>
                    107: #include <arpa/nameser.h>
                    108: #include <ctype.h>
                    109: #include <errno.h>
                    110: #include <netdb.h>
                    111: #include <resolv.h>
                    112: #include <stdio.h>
                    113: #include <stdlib.h>
1.6       christos  114: #include <unistd.h>
1.1       christos  115: #include <string.h>
                    116: #include "port_after.h"
                    117:
1.5       christos  118: #if 0
1.4       christos  119: #ifdef __weak_alias
                    120: __weak_alias(res_nquery,_res_nquery)
                    121: __weak_alias(res_nsearch,_res_nsearch)
                    122: __weak_alias(res_nquerydomain,__res_nquerydomain)
                    123: __weak_alias(res_hostalias,__res_hostalias)
                    124: #endif
1.5       christos  125: #endif
1.4       christos  126:
1.1       christos  127: /* Options.  Leave them on. */
1.11      christos  128: #ifndef DEBUG
1.1       christos  129: #define DEBUG
1.11      christos  130: #endif
1.1       christos  131:
                    132: #if PACKETSZ > 1024
                    133: #define MAXPACKET      PACKETSZ
                    134: #else
                    135: #define MAXPACKET      1024
                    136: #endif
                    137:
1.8       christos  138: /*%
1.1       christos  139:  * Formulate a normal query, send, and await answer.
                    140:  * Returned answer is placed in supplied buffer "answer".
                    141:  * Perform preliminary check of answer, returning success only
                    142:  * if no error is indicated and the answer count is nonzero.
                    143:  * Return the size of the response on success, -1 on error.
                    144:  * Error number is left in H_ERRNO.
                    145:  *
                    146:  * Caller must parse answer and determine whether it answers the question.
                    147:  */
                    148: int
                    149: res_nquery(res_state statp,
1.8       christos  150:           const char *name,    /*%< domain name */
                    151:           int class, int type, /*%< class and type of query */
                    152:           u_char *answer,      /*%< buffer to put answer */
                    153:           int anslen)          /*%< size of answer buffer */
1.1       christos  154: {
                    155:        u_char buf[MAXPACKET];
1.2       christos  156:        HEADER *hp = (HEADER *)(void *)answer;
1.1       christos  157:        u_int oflags;
1.10      christos  158:        u_char *rdata;
1.11.14.1! riz       159:        int n;
1.1       christos  160:
                    161:        oflags = statp->_flags;
                    162:
                    163: again:
1.8       christos  164:        hp->rcode = NOERROR;    /*%< default */
1.1       christos  165: #ifdef DEBUG
                    166:        if (statp->options & RES_DEBUG)
                    167:                printf(";; res_query(%s, %d, %d)\n", name, class, type);
                    168: #endif
                    169:
                    170:        n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
                    171:                         buf, sizeof(buf));
                    172: #ifdef RES_USE_EDNS0
                    173:        if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 &&
1.10      christos  174:            (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID)) != 0U) {
1.1       christos  175:                n = res_nopt(statp, n, buf, sizeof(buf), anslen);
1.10      christos  176:                rdata = &buf[n];
                    177:                if (n > 0 && (statp->options & RES_NSID) != 0U) {
                    178:                        n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
                    179:                                           NS_OPT_NSID, 0, NULL);
                    180:                }
                    181:        }
1.1       christos  182: #endif
                    183:        if (n <= 0) {
                    184: #ifdef DEBUG
                    185:                if (statp->options & RES_DEBUG)
                    186:                        printf(";; res_query: mkquery failed\n");
                    187: #endif
                    188:                RES_SET_H_ERRNO(statp, NO_RECOVERY);
                    189:                return (n);
                    190:        }
1.10      christos  191:
1.1       christos  192:        n = res_nsend(statp, buf, n, answer, anslen);
                    193:        if (n < 0) {
                    194: #ifdef RES_USE_EDNS0
                    195:                /* if the query choked with EDNS0, retry without EDNS0 */
                    196:                if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U &&
                    197:                    ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
                    198:                        statp->_flags |= RES_F_EDNS0ERR;
                    199:                        if (statp->options & RES_DEBUG)
                    200:                                printf(";; res_nquery: retry without EDNS0\n");
                    201:                        goto again;
                    202:                }
                    203: #endif
                    204: #ifdef DEBUG
                    205:                if (statp->options & RES_DEBUG)
                    206:                        printf(";; res_query: send error\n");
                    207: #endif
                    208:                RES_SET_H_ERRNO(statp, TRY_AGAIN);
                    209:                return (n);
                    210:        }
                    211:
                    212:        if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) {
                    213: #ifdef DEBUG
                    214:                if (statp->options & RES_DEBUG)
                    215:                        printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n",
                    216:                               p_rcode(hp->rcode),
                    217:                               ntohs(hp->ancount),
                    218:                               ntohs(hp->nscount),
                    219:                               ntohs(hp->arcount));
                    220: #endif
                    221:                switch (hp->rcode) {
                    222:                case NXDOMAIN:
                    223:                        RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
                    224:                        break;
                    225:                case SERVFAIL:
                    226:                        RES_SET_H_ERRNO(statp, TRY_AGAIN);
                    227:                        break;
                    228:                case NOERROR:
                    229:                        RES_SET_H_ERRNO(statp, NO_DATA);
                    230:                        break;
                    231:                case FORMERR:
                    232:                case NOTIMP:
                    233:                case REFUSED:
                    234:                default:
                    235:                        RES_SET_H_ERRNO(statp, NO_RECOVERY);
                    236:                        break;
                    237:                }
                    238:                return (-1);
                    239:        }
                    240:        return (n);
                    241: }
                    242:
1.8       christos  243: /*%
1.1       christos  244:  * Formulate a normal query, send, and retrieve answer in supplied buffer.
                    245:  * Return the size of the response on success, -1 on error.
                    246:  * If enabled, implement search rules until answer or unrecoverable failure
                    247:  * is detected.  Error code, if any, is left in H_ERRNO.
                    248:  */
                    249: int
                    250: res_nsearch(res_state statp,
1.8       christos  251:            const char *name,   /*%< domain name */
                    252:            int class, int type,        /*%< class and type of query */
                    253:            u_char *answer,     /*%< buffer to put answer */
                    254:            int anslen)         /*%< size of answer */
1.1       christos  255: {
                    256:        const char *cp, * const *domain;
1.2       christos  257:        HEADER *hp = (HEADER *)(void *)answer;
1.1       christos  258:        char tmp[NS_MAXDNAME];
                    259:        u_int dots;
                    260:        int trailing_dot, ret, saved_herrno;
                    261:        int got_nodata = 0, got_servfail = 0, root_on_list = 0;
                    262:        int tried_as_is = 0;
                    263:        int searched = 0;
                    264:
                    265:        errno = 0;
1.8       christos  266:        RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);  /*%< True if we never query. */
1.1       christos  267:        dots = 0;
                    268:        for (cp = name; *cp != '\0'; cp++)
                    269:                dots += (*cp == '.');
                    270:        trailing_dot = 0;
                    271:        if (cp > name && *--cp == '.')
                    272:                trailing_dot++;
                    273:
                    274:        /* If there aren't any dots, it could be a user-level alias. */
                    275:        if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL)
                    276:                return (res_nquery(statp, cp, class, type, answer, anslen));
                    277:
                    278:        /*
                    279:         * If there are enough dots in the name, let's just give it a
                    280:         * try 'as is'. The threshold can be set with the "ndots" option.
                    281:         * Also, query 'as is', if there is a trailing dot in the name.
                    282:         */
                    283:        saved_herrno = -1;
                    284:        if (dots >= statp->ndots || trailing_dot) {
                    285:                ret = res_nquerydomain(statp, name, NULL, class, type,
                    286:                                         answer, anslen);
                    287:                if (ret > 0 || trailing_dot)
                    288:                        return (ret);
                    289:                saved_herrno = statp->res_h_errno;
                    290:                tried_as_is++;
                    291:        }
                    292:
                    293:        /*
                    294:         * We do at least one level of search if
                    295:         *      - there is no dot and RES_DEFNAME is set, or
                    296:         *      - there is at least one dot, there is no trailing dot,
                    297:         *        and RES_DNSRCH is set.
                    298:         */
                    299:        if ((!dots && (statp->options & RES_DEFNAMES) != 0U) ||
                    300:            (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) {
                    301:                int done = 0;
                    302:
                    303:                for (domain = (const char * const *)statp->dnsrch;
                    304:                     *domain && !done;
                    305:                     domain++) {
                    306:                        searched = 1;
                    307:
                    308:                        if (domain[0][0] == '\0' ||
                    309:                            (domain[0][0] == '.' && domain[0][1] == '\0'))
                    310:                                root_on_list++;
                    311:
                    312:                        ret = res_nquerydomain(statp, name, *domain,
                    313:                                               class, type,
                    314:                                               answer, anslen);
                    315:                        if (ret > 0)
                    316:                                return (ret);
                    317:
                    318:                        /*
                    319:                         * If no server present, give up.
                    320:                         * If name isn't found in this domain,
                    321:                         * keep trying higher domains in the search list
                    322:                         * (if that's enabled).
                    323:                         * On a NO_DATA error, keep trying, otherwise
                    324:                         * a wildcard entry of another type could keep us
                    325:                         * from finding this entry higher in the domain.
                    326:                         * If we get some other error (negative answer or
                    327:                         * server failure), then stop searching up,
                    328:                         * but try the input name below in case it's
                    329:                         * fully-qualified.
                    330:                         */
                    331:                        if (errno == ECONNREFUSED) {
                    332:                                RES_SET_H_ERRNO(statp, TRY_AGAIN);
                    333:                                return (-1);
                    334:                        }
                    335:
                    336:                        switch (statp->res_h_errno) {
                    337:                        case NO_DATA:
                    338:                                got_nodata++;
                    339:                                /* FALLTHROUGH */
                    340:                        case HOST_NOT_FOUND:
                    341:                                /* keep trying */
                    342:                                break;
                    343:                        case TRY_AGAIN:
                    344:                                if (hp->rcode == SERVFAIL) {
                    345:                                        /* try next search element, if any */
                    346:                                        got_servfail++;
                    347:                                        break;
                    348:                                }
                    349:                                /* FALLTHROUGH */
                    350:                        default:
                    351:                                /* anything else implies that we're done */
                    352:                                done++;
                    353:                        }
                    354:
                    355:                        /* if we got here for some reason other than DNSRCH,
                    356:                         * we only wanted one iteration of the loop, so stop.
                    357:                         */
                    358:                        if ((statp->options & RES_DNSRCH) == 0U)
                    359:                                done++;
                    360:                }
                    361:        }
                    362:
                    363:        /*
                    364:         * If the query has not already been tried as is then try it
                    365:         * unless RES_NOTLDQUERY is set and there were no dots.
                    366:         */
                    367:        if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) &&
                    368:            !(tried_as_is || root_on_list)) {
                    369:                ret = res_nquerydomain(statp, name, NULL, class, type,
                    370:                                       answer, anslen);
                    371:                if (ret > 0)
                    372:                        return (ret);
                    373:        }
                    374:
                    375:        /* if we got here, we didn't satisfy the search.
                    376:         * if we did an initial full query, return that query's H_ERRNO
                    377:         * (note that we wouldn't be here if that query had succeeded).
                    378:         * else if we ever got a nodata, send that back as the reason.
                    379:         * else send back meaningless H_ERRNO, that being the one from
                    380:         * the last DNSRCH we did.
                    381:         */
                    382:        if (saved_herrno != -1)
                    383:                RES_SET_H_ERRNO(statp, saved_herrno);
                    384:        else if (got_nodata)
                    385:                RES_SET_H_ERRNO(statp, NO_DATA);
                    386:        else if (got_servfail)
                    387:                RES_SET_H_ERRNO(statp, TRY_AGAIN);
                    388:        return (-1);
                    389: }
                    390:
1.8       christos  391: /*%
1.1       christos  392:  * Perform a call on res_query on the concatenation of name and domain,
                    393:  * removing a trailing dot from name if domain is NULL.
                    394:  */
                    395: int
                    396: res_nquerydomain(res_state statp,
                    397:            const char *name,
                    398:            const char *domain,
1.8       christos  399:            int class, int type,        /*%< class and type of query */
                    400:            u_char *answer,             /*%< buffer to put answer */
                    401:            int anslen)         /*%< size of answer */
1.1       christos  402: {
                    403:        char nbuf[MAXDNAME];
                    404:        const char *longname = nbuf;
                    405:        int n, d;
                    406:
                    407: #ifdef DEBUG
                    408:        if (statp->options & RES_DEBUG)
                    409:                printf(";; res_nquerydomain(%s, %s, %d, %d)\n",
                    410:                       name, domain?domain:"<Nil>", class, type);
                    411: #endif
                    412:        if (domain == NULL) {
                    413:                /*
                    414:                 * Check for trailing '.';
                    415:                 * copy without '.' if present.
                    416:                 */
                    417:                n = strlen(name);
                    418:                if (n >= MAXDNAME) {
                    419:                        RES_SET_H_ERRNO(statp, NO_RECOVERY);
                    420:                        return (-1);
                    421:                }
                    422:                n--;
                    423:                if (n >= 0 && name[n] == '.') {
1.2       christos  424:                        strncpy(nbuf, name, (size_t)n);
1.1       christos  425:                        nbuf[n] = '\0';
                    426:                } else
                    427:                        longname = name;
                    428:        } else {
                    429:                n = strlen(name);
                    430:                d = strlen(domain);
                    431:                if (n + d + 1 >= MAXDNAME) {
                    432:                        RES_SET_H_ERRNO(statp, NO_RECOVERY);
                    433:                        return (-1);
                    434:                }
                    435:                sprintf(nbuf, "%s.%s", name, domain);
                    436:        }
                    437:        return (res_nquery(statp, longname, class, type, answer, anslen));
                    438: }
                    439:
                    440: const char *
                    441: res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) {
                    442:        char *file, *cp1, *cp2;
                    443:        char buf[BUFSIZ];
                    444:        FILE *fp;
                    445:
                    446:        if (statp->options & RES_NOALIASES)
                    447:                return (NULL);
1.6       christos  448:        /*
                    449:         * forbid hostaliases for setuid binary, due to possible security
                    450:         * breach.
                    451:         */
                    452:        if (issetugid())
                    453:                return (NULL);
1.1       christos  454:        file = getenv("HOSTALIASES");
                    455:        if (file == NULL || (fp = fopen(file, "r")) == NULL)
                    456:                return (NULL);
                    457:        buf[sizeof(buf) - 1] = '\0';
                    458:        while (fgets(buf, sizeof(buf), fp)) {
                    459:                for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
                    460:                        ;
                    461:                if (!*cp1)
                    462:                        break;
                    463:                *cp1 = '\0';
                    464:                if (ns_samename(buf, name) == 1) {
                    465:                        while (isspace((unsigned char)*++cp1))
                    466:                                ;
                    467:                        if (!*cp1)
                    468:                                break;
                    469:                        for (cp2 = cp1 + 1; *cp2 &&
                    470:                             !isspace((unsigned char)*cp2); ++cp2)
                    471:                                ;
                    472:                        *cp2 = '\0';
                    473:                        strncpy(dst, cp1, siz - 1);
                    474:                        dst[siz - 1] = '\0';
                    475:                        fclose(fp);
                    476:                        return (dst);
                    477:                }
                    478:        }
                    479:        fclose(fp);
                    480:        return (NULL);
                    481: }
1.8       christos  482:
                    483: /*! \file */

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