/* $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);
}