| /* $NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $ */ |
| |
| /* |
| * Copyright (c) 1988, 1993 |
| * The Regents of the University of California. All rights reserved. |
| * |
| * Redistribution and use in source and binary forms, with or without |
| * modification, are permitted provided that the following conditions |
| * are met: |
| * 1. Redistributions of source code must retain the above copyright |
| * notice, this list of conditions and the following disclaimer. |
| * 2. Redistributions in binary form must reproduce the above copyright |
| * notice, this list of conditions and the following disclaimer in the |
| * documentation and/or other materials provided with the distribution. |
| * 3. All advertising materials mentioning features or use of this software |
| * must display the following acknowledgement: |
| * This product includes software developed by the University of |
| * California, Berkeley and its contributors. |
| * 4. Neither the name of the University nor the names of its contributors |
| * may be used to endorse or promote products derived from this software |
| * without specific prior written permission. |
| * |
| * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND |
| * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE |
| * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE |
| * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL |
| * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS |
| * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) |
| * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT |
| * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY |
| * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF |
| * SUCH DAMAGE. |
| */ |
| |
| /* |
| * Portions Copyright (c) 1993 by Digital Equipment Corporation. |
| * |
| * Permission to use, copy, modify, and distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies, and that |
| * the name of Digital Equipment Corporation not be used in advertising or |
| * publicity pertaining to distribution of the document or software without |
| * specific, written prior permission. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL |
| * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES |
| * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT |
| * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL |
| * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR |
| * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS |
| * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS |
| * SOFTWARE. |
| */ |
| |
| /* |
| * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC") |
| * Portions Copyright (c) 1996-1999 by Internet Software Consortium. |
| * |
| * Permission to use, copy, modify, and distribute this software for any |
| * purpose with or without fee is hereby granted, provided that the above |
| * copyright notice and this permission notice appear in all copies. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES |
| * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF |
| * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR |
| * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES |
| * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN |
| * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT |
| * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. |
| */ |
| |
| #include <sys/cdefs.h> |
| #if defined(LIBC_SCCS) && !defined(lint) |
| #ifdef notdef |
| static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; |
| static const char rcsid[] = "Id: res_query.c,v 1.2.2.3.4.2 2004/03/16 12:34:19 marka Exp"; |
| #else |
| __RCSID("$NetBSD: res_query.c,v 1.7 2006/01/24 17:41:25 christos Exp $"); |
| #endif |
| #endif /* LIBC_SCCS and not lint */ |
| |
| |
| |
| #include <sys/types.h> |
| #include <sys/param.h> |
| #include <netinet/in.h> |
| #include <arpa/inet.h> |
| #include <arpa/nameser.h> |
| #include <ctype.h> |
| #include <errno.h> |
| #include <netdb.h> |
| #ifdef ANDROID_CHANGES |
| #include "resolv_cache.h" |
| #include "resolv_private.h" |
| #else |
| #include <resolv.h> |
| #endif |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <string.h> |
| |
| #define DISABLE_HOST_ALIAS 1 |
| |
| /* Options. Leave them on. */ |
| #ifndef DEBUG |
| #define DEBUG |
| #endif |
| |
| #if PACKETSZ > 1024 |
| #define MAXPACKET PACKETSZ |
| #else |
| #define MAXPACKET 1024 |
| #endif |
| |
| /* |
| * Formulate a normal query, send, and await answer. |
| * Returned answer is placed in supplied buffer "answer". |
| * Perform preliminary check of answer, returning success only |
| * if no error is indicated and the answer count is nonzero. |
| * Return the size of the response on success, -1 on error. |
| * Error number is left in H_ERRNO. |
| * |
| * Caller must parse answer and determine whether it answers the question. |
| */ |
| int |
| res_nquery(res_state statp, |
| const char *name, /* domain name */ |
| int class, int type, /* class and type of query */ |
| u_char *answer, /* buffer to put answer */ |
| int anslen) /* size of answer buffer */ |
| { |
| u_char buf[MAXPACKET]; |
| HEADER *hp = (HEADER *)(void *)answer; |
| int n; |
| u_int oflags; |
| |
| oflags = statp->_flags; |
| |
| again: |
| hp->rcode = NOERROR; /* default */ |
| |
| #ifdef DEBUG |
| if (statp->options & RES_DEBUG) |
| printf(";; res_query(%s, %d, %d)\n", name, class, type); |
| #endif |
| |
| n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, |
| buf, sizeof(buf)); |
| #ifdef RES_USE_EDNS0 |
| if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && |
| (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U) |
| n = res_nopt(statp, n, buf, sizeof(buf), anslen); |
| #endif |
| if (n <= 0) { |
| #ifdef DEBUG |
| if (statp->options & RES_DEBUG) |
| printf(";; res_query: mkquery failed\n"); |
| #endif |
| RES_SET_H_ERRNO(statp, NO_RECOVERY); |
| return (n); |
| } |
| n = res_nsend(statp, buf, n, answer, anslen); |
| if (n < 0) { |
| #ifdef RES_USE_EDNS0 |
| /* if the query choked with EDNS0, retry without EDNS0 */ |
| if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && |
| ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { |
| statp->_flags |= RES_F_EDNS0ERR; |
| if (statp->options & RES_DEBUG) |
| printf(";; res_nquery: retry without EDNS0\n"); |
| goto again; |
| } |
| #endif |
| #ifdef DEBUG |
| if (statp->options & RES_DEBUG) |
| printf(";; res_query: send error\n"); |
| #endif |
| RES_SET_H_ERRNO(statp, TRY_AGAIN); |
| return (n); |
| } |
| |
| if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { |
| #ifdef DEBUG |
| if (statp->options & RES_DEBUG) |
| printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", |
| p_rcode(hp->rcode), |
| ntohs(hp->ancount), |
| ntohs(hp->nscount), |
| ntohs(hp->arcount)); |
| #endif |
| switch (hp->rcode) { |
| case NXDOMAIN: |
| RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); |
| break; |
| case SERVFAIL: |
| RES_SET_H_ERRNO(statp, TRY_AGAIN); |
| break; |
| case NOERROR: |
| RES_SET_H_ERRNO(statp, NO_DATA); |
| break; |
| case FORMERR: |
| case NOTIMP: |
| case REFUSED: |
| default: |
| RES_SET_H_ERRNO(statp, NO_RECOVERY); |
| break; |
| } |
| return (-1); |
| } |
| return (n); |
| } |
| |
| /* |
| * Formulate a normal query, send, and retrieve answer in supplied buffer. |
| * Return the size of the response on success, -1 on error. |
| * If enabled, implement search rules until answer or unrecoverable failure |
| * is detected. Error code, if any, is left in H_ERRNO. |
| */ |
| int |
| res_nsearch(res_state statp, |
| const char *name, /* domain name */ |
| int class, int type, /* class and type of query */ |
| u_char *answer, /* buffer to put answer */ |
| int anslen) /* size of answer */ |
| { |
| const char *cp, * const *domain; |
| HEADER *hp = (HEADER *)(void *)answer; |
| char tmp[NS_MAXDNAME]; |
| u_int dots; |
| int trailing_dot, ret, saved_herrno; |
| int got_nodata = 0, got_servfail = 0, root_on_list = 0; |
| int tried_as_is = 0; |
| int searched = 0; |
| |
| errno = 0; |
| RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /* True if we never query. */ |
| |
| dots = 0; |
| for (cp = name; *cp != '\0'; cp++) |
| dots += (*cp == '.'); |
| trailing_dot = 0; |
| if (cp > name && *--cp == '.') |
| trailing_dot++; |
| |
| /* If there aren't any dots, it could be a user-level alias. */ |
| if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) |
| return (res_nquery(statp, cp, class, type, answer, anslen)); |
| |
| /* |
| * If there are enough dots in the name, let's just give it a |
| * try 'as is'. The threshold can be set with the "ndots" option. |
| * Also, query 'as is', if there is a trailing dot in the name. |
| */ |
| saved_herrno = -1; |
| if (dots >= statp->ndots || trailing_dot) { |
| ret = res_nquerydomain(statp, name, NULL, class, type, |
| answer, anslen); |
| if (ret > 0 || trailing_dot) |
| return (ret); |
| saved_herrno = statp->res_h_errno; |
| tried_as_is++; |
| } |
| |
| /* |
| * We do at least one level of search if |
| * - there is no dot and RES_DEFNAME is set, or |
| * - there is at least one dot, there is no trailing dot, |
| * and RES_DNSRCH is set. |
| */ |
| if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || |
| (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { |
| int done = 0; |
| |
| /* Unfortunately we need to load network-specific info |
| * (dns servers, search domains) before |
| * the domain stuff is tried. Will have a better |
| * fix after thread pools are used as this will |
| * be loaded once for the thread instead of each |
| * time a query is tried. |
| */ |
| _resolv_populate_res_for_net(statp); |
| |
| for (domain = (const char * const *)statp->dnsrch; |
| *domain && !done; |
| domain++) { |
| searched = 1; |
| |
| if (domain[0][0] == '\0' || |
| (domain[0][0] == '.' && domain[0][1] == '\0')) |
| root_on_list++; |
| |
| ret = res_nquerydomain(statp, name, *domain, |
| class, type, |
| answer, anslen); |
| if (ret > 0) |
| return (ret); |
| |
| /* |
| * If no server present, give up. |
| * If name isn't found in this domain, |
| * keep trying higher domains in the search list |
| * (if that's enabled). |
| * On a NO_DATA error, keep trying, otherwise |
| * a wildcard entry of another type could keep us |
| * from finding this entry higher in the domain. |
| * If we get some other error (negative answer or |
| * server failure), then stop searching up, |
| * but try the input name below in case it's |
| * fully-qualified. |
| */ |
| if (errno == ECONNREFUSED) { |
| RES_SET_H_ERRNO(statp, TRY_AGAIN); |
| return (-1); |
| } |
| |
| switch (statp->res_h_errno) { |
| case NO_DATA: |
| got_nodata++; |
| /* FALLTHROUGH */ |
| case HOST_NOT_FOUND: |
| /* keep trying */ |
| break; |
| case TRY_AGAIN: |
| if (hp->rcode == SERVFAIL) { |
| /* try next search element, if any */ |
| got_servfail++; |
| break; |
| } |
| /* FALLTHROUGH */ |
| default: |
| /* anything else implies that we're done */ |
| done++; |
| } |
| |
| /* if we got here for some reason other than DNSRCH, |
| * we only wanted one iteration of the loop, so stop. |
| */ |
| if ((statp->options & RES_DNSRCH) == 0U) |
| done++; |
| } |
| } |
| |
| /* |
| * If the query has not already been tried as is then try it |
| * unless RES_NOTLDQUERY is set and there were no dots. |
| */ |
| if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && |
| !(tried_as_is || root_on_list)) { |
| ret = res_nquerydomain(statp, name, NULL, class, type, |
| answer, anslen); |
| if (ret > 0) |
| return (ret); |
| } |
| |
| /* if we got here, we didn't satisfy the search. |
| * if we did an initial full query, return that query's H_ERRNO |
| * (note that we wouldn't be here if that query had succeeded). |
| * else if we ever got a nodata, send that back as the reason. |
| * else send back meaningless H_ERRNO, that being the one from |
| * the last DNSRCH we did. |
| */ |
| if (saved_herrno != -1) |
| RES_SET_H_ERRNO(statp, saved_herrno); |
| else if (got_nodata) |
| RES_SET_H_ERRNO(statp, NO_DATA); |
| else if (got_servfail) |
| RES_SET_H_ERRNO(statp, TRY_AGAIN); |
| return (-1); |
| } |
| |
| /* |
| * Perform a call on res_query on the concatenation of name and domain, |
| * removing a trailing dot from name if domain is NULL. |
| */ |
| int |
| res_nquerydomain(res_state statp, |
| const char *name, |
| const char *domain, |
| int class, int type, /* class and type of query */ |
| u_char *answer, /* buffer to put answer */ |
| int anslen) /* size of answer */ |
| { |
| char nbuf[MAXDNAME]; |
| const char *longname = nbuf; |
| int n, d; |
| |
| #ifdef DEBUG |
| if (statp->options & RES_DEBUG) |
| printf(";; res_nquerydomain(%s, %s, %d, %d)\n", |
| name, domain?domain:"<Nil>", class, type); |
| #endif |
| if (domain == NULL) { |
| /* |
| * Check for trailing '.'; |
| * copy without '.' if present. |
| */ |
| n = strlen(name); |
| if (n >= MAXDNAME) { |
| RES_SET_H_ERRNO(statp, NO_RECOVERY); |
| return (-1); |
| } |
| n--; |
| if (n >= 0 && name[n] == '.') { |
| strncpy(nbuf, name, (size_t)n); |
| nbuf[n] = '\0'; |
| } else |
| longname = name; |
| } else { |
| n = strlen(name); |
| d = strlen(domain); |
| if (n + d + 1 >= MAXDNAME) { |
| RES_SET_H_ERRNO(statp, NO_RECOVERY); |
| return (-1); |
| } |
| snprintf(nbuf, sizeof(nbuf), "%s.%s", name, domain); |
| } |
| return (res_nquery(statp, longname, class, type, answer, anslen)); |
| } |
| |
| const char * |
| res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { |
| return (NULL); |
| } |
