046c3635cd
From http://www.isc.org/downloads/libbind/ The libbind functions have been separated from the BIND suite as of BIND 9.6.0. Originally from older versions of BIND, they have been continually maintained and improved but not installed by default with BIND 9. This standard resolver library contains the same historical functions and headers included with many Unix operating systems. In fact, most implementations are based on the same original code. At present, NetBSD maintains libbind code, now known as "netresolv".
441 lines
13 KiB
C
441 lines
13 KiB
C
/*
|
|
* Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC")
|
|
* Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium.
|
|
*
|
|
* Permission to use, copy, modify, and/or 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.
|
|
*/
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
|
|
#if defined(LIBC_SCCS) && !defined(lint)
|
|
static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93";
|
|
static const char rcsid[] = "$Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp $";
|
|
#endif /* LIBC_SCCS and not lint */
|
|
|
|
#include "port_before.h"
|
|
#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>
|
|
#include <resolv.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include "port_after.h"
|
|
|
|
/* Options. Leave them on. */
|
|
#define DEBUG
|
|
|
|
#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 *) answer;
|
|
u_int oflags;
|
|
u_char *rdata;
|
|
int n;
|
|
|
|
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|RES_NSID))) {
|
|
n = res_nopt(statp, n, buf, sizeof(buf), anslen);
|
|
rdata = &buf[n];
|
|
if (n > 0 && (statp->options & RES_NSID) != 0U) {
|
|
n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata,
|
|
NS_OPT_NSID, 0, NULL);
|
|
}
|
|
}
|
|
#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 *) 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;
|
|
|
|
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, 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);
|
|
}
|
|
sprintf(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) {
|
|
char *file, *cp1, *cp2;
|
|
char buf[BUFSIZ];
|
|
FILE *fp;
|
|
|
|
if (statp->options & RES_NOALIASES)
|
|
return (NULL);
|
|
file = getenv("HOSTALIASES");
|
|
if (file == NULL || (fp = fopen(file, "r")) == NULL)
|
|
return (NULL);
|
|
setbuf(fp, NULL);
|
|
buf[sizeof(buf) - 1] = '\0';
|
|
while (fgets(buf, sizeof(buf), fp)) {
|
|
for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1)
|
|
;
|
|
if (!*cp1)
|
|
break;
|
|
*cp1 = '\0';
|
|
if (ns_samename(buf, name) == 1) {
|
|
while (isspace((unsigned char)*++cp1))
|
|
;
|
|
if (!*cp1)
|
|
break;
|
|
for (cp2 = cp1 + 1; *cp2 &&
|
|
!isspace((unsigned char)*cp2); ++cp2)
|
|
;
|
|
*cp2 = '\0';
|
|
strncpy(dst, cp1, siz - 1);
|
|
dst[siz - 1] = '\0';
|
|
fclose(fp);
|
|
return (dst);
|
|
}
|
|
}
|
|
fclose(fp);
|
|
return (NULL);
|
|
}
|
|
|
|
/*! \file */
|