glibc/resolv/res_query.c
2011-05-07 13:05:19 -04:00

633 lines
18 KiB
C

/*
* 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.
* 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.
*/
/*
* 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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
* CONSORTIUM 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[] = "$BINDId: res_query.c,v 8.20 2000/02/29 05:39:12 vixie Exp $";
#endif /* LIBC_SCCS and not lint */
#include <assert.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>
/* Options. Leave them on. */
/* #undef DEBUG */
#if PACKETSZ > 65536
#define MAXPACKET PACKETSZ
#else
#define MAXPACKET 65536
#endif
#define QUERYSIZE (HFIXEDSZ + QFIXEDSZ + MAXCDNAME + 1)
static int
__libc_res_nquerydomain(res_state statp, const char *name, const char *domain,
int class, int type, u_char *answer, int anslen,
u_char **answerp, u_char **answerp2, int *nanswerp2,
int *resplen2);
/*
* 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
__libc_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 **answerp, /* if buffer needs to be enlarged */
u_char **answerp2,
int *nanswerp2,
int *resplen2)
{
HEADER *hp = (HEADER *) answer;
int n, use_malloc = 0;
u_int oflags = statp->_flags;
size_t bufsize = (type == T_UNSPEC ? 2 : 1) * QUERYSIZE;
u_char *buf = alloca (bufsize);
u_char *query1 = buf;
int nquery1 = -1;
u_char *query2 = NULL;
int nquery2 = 0;
again:
hp->rcode = NOERROR; /* default */
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_query(%s, %d, %d)\n", name, class, type);
#endif
if (type == T_UNSPEC)
{
n = res_nmkquery(statp, QUERY, name, class, T_A, NULL, 0, NULL,
query1, bufsize);
if (n > 0)
{
if ((oflags & RES_F_EDNS0ERR) == 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
{
n = __res_nopt(statp, n, query1, bufsize, anslen / 2);
if (n < 0)
goto unspec_nomem;
}
nquery1 = n;
/* Align the buffer. */
int npad = ((nquery1 + __alignof__ (HEADER) - 1)
& ~(__alignof__ (HEADER) - 1)) - nquery1;
if (n > bufsize - npad)
{
n = -1;
goto unspec_nomem;
}
int nused = n + npad;
query2 = buf + nused;
n = res_nmkquery(statp, QUERY, name, class, T_AAAA, NULL, 0,
NULL, query2, bufsize - nused);
if (n > 0
&& (oflags & RES_F_EDNS0ERR) == 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
n = __res_nopt(statp, n, query2, bufsize - nused - n,
anslen / 2);
nquery2 = n;
}
unspec_nomem:;
}
else
{
n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL,
query1, bufsize);
if (n > 0
&& (oflags & RES_F_EDNS0ERR) == 0
&& (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0)
n = __res_nopt(statp, n, query1, bufsize, anslen);
nquery1 = n;
}
if (__builtin_expect (n <= 0, 0) && !use_malloc) {
/* Retry just in case res_nmkquery failed because of too
short buffer. Shouldn't happen. */
bufsize = (type == T_UNSPEC ? 2 : 1) * MAXPACKET;
buf = malloc (bufsize);
if (buf != NULL) {
query1 = buf;
use_malloc = 1;
goto again;
}
}
if (__builtin_expect (n <= 0, 0)) {
/* If the query choked with EDNS0, retry without EDNS0. */
if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0
&& ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) {
statp->_flags |= RES_F_EDNS0ERR;
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_nquery: retry without EDNS0\n");
#endif
goto again;
}
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_query: mkquery failed\n");
#endif
RES_SET_H_ERRNO(statp, NO_RECOVERY);
if (use_malloc)
free (buf);
return (n);
}
assert (answerp == NULL || (void *) *answerp == (void *) answer);
n = __libc_res_nsend(statp, query1, nquery1, query2, nquery2, answer,
anslen, answerp, answerp2, nanswerp2, resplen2);
if (use_malloc)
free (buf);
if (n < 0) {
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf(";; res_query: send error\n");
#endif
RES_SET_H_ERRNO(statp, TRY_AGAIN);
return (n);
}
if (answerp != NULL)
/* __libc_res_nsend might have reallocated the buffer. */
hp = (HEADER *) *answerp;
/* We simplify the following tests by assigning HP to HP2. It
is easy to verify that this is the same as ignoring all
tests of HP2. */
HEADER *hp2 = answerp2 ? (HEADER *) *answerp2 : hp;
if (n < (int) sizeof (HEADER) && answerp2 != NULL
&& *resplen2 > (int) sizeof (HEADER))
{
/* Special case of partial answer. */
assert (hp != hp2);
hp = hp2;
}
else if (answerp2 != NULL && *resplen2 < (int) sizeof (HEADER)
&& n > (int) sizeof (HEADER))
{
/* Special case of partial answer. */
assert (hp != hp2);
hp2 = hp;
}
if ((hp->rcode != NOERROR || ntohs(hp->ancount) == 0)
&& (hp2->rcode != NOERROR || ntohs(hp2->ancount) == 0)) {
#ifdef DEBUG
if (statp->options & RES_DEBUG) {
printf(";; rcode = %d, ancount=%d\n", hp->rcode,
ntohs(hp->ancount));
if (hp != hp2)
printf(";; rcode2 = %d, ancount2=%d\n", hp2->rcode,
ntohs(hp2->ancount));
}
#endif
switch (hp->rcode == NOERROR ? hp2->rcode : hp->rcode) {
case NXDOMAIN:
if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
|| (hp2->rcode == NOERROR
&& ntohs (hp2->ancount) != 0))
goto success;
RES_SET_H_ERRNO(statp, HOST_NOT_FOUND);
break;
case SERVFAIL:
RES_SET_H_ERRNO(statp, TRY_AGAIN);
break;
case NOERROR:
if (ntohs (hp->ancount) != 0
|| ntohs (hp2->ancount) != 0)
goto success;
RES_SET_H_ERRNO(statp, NO_DATA);
break;
case FORMERR:
case NOTIMP:
/* Servers must not reply to AAAA queries with
NOTIMP etc but some of them do. */
if ((hp->rcode == NOERROR && ntohs (hp->ancount) != 0)
|| (hp2->rcode == NOERROR
&& ntohs (hp2->ancount) != 0))
goto success;
/* FALLTHROUGH */
case REFUSED:
default:
RES_SET_H_ERRNO(statp, NO_RECOVERY);
break;
}
return (-1);
}
success:
return (n);
}
libresolv_hidden_def (__libc_res_nquery)
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 */
{
return __libc_res_nquery(statp, name, class, type, answer, anslen,
NULL, NULL, NULL, NULL);
}
libresolv_hidden_def (res_nquery)
/*
* 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
__libc_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 */
u_char **answerp,
u_char **answerp2,
int *nanswerp2,
int *resplen2)
{
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;
__set_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 (__libc_res_nquery(statp, cp, class, type, answer,
anslen, answerp, answerp2,
nanswerp2, resplen2));
#ifdef DEBUG
if (statp->options & RES_DEBUG)
printf("dots=%d, statp->ndots=%d, trailing_dot=%d, name=%s\n",
(int)dots,(int)statp->ndots,(int)trailing_dot,name);
#endif
/*
* 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 = __libc_res_nquerydomain(statp, name, NULL, class, type,
answer, anslen, answerp,
answerp2, nanswerp2, resplen2);
if (ret > 0 || trailing_dot)
return (ret);
saved_herrno = h_errno;
tried_as_is++;
if (answerp && *answerp != answer) {
answer = *answerp;
anslen = MAXPACKET;
}
if (answerp2
&& (*answerp2 < answer || *answerp2 >= answer + anslen))
{
free (*answerp2);
*answerp2 = NULL;
}
}
/*
* 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) != 0) ||
(dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0)) {
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 = __libc_res_nquerydomain(statp, name, *domain,
class, type,
answer, anslen, answerp,
answerp2, nanswerp2,
resplen2);
if (ret > 0)
return (ret);
if (answerp && *answerp != answer) {
answer = *answerp;
anslen = MAXPACKET;
}
if (answerp2
&& (*answerp2 < answer
|| *answerp2 >= answer + anslen))
{
free (*answerp2);
*answerp2 = NULL;
}
/*
* 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) == 0)
done++;
}
}
/*
* f 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) == 0)
&& !(tried_as_is || root_on_list)) {
ret = __libc_res_nquerydomain(statp, name, NULL, class, type,
answer, anslen, answerp,
answerp2, nanswerp2, resplen2);
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 (answerp2 && (*answerp2 < answer || *answerp2 >= answer + anslen))
{
free (*answerp2);
*answerp2 = NULL;
}
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);
}
libresolv_hidden_def (__libc_res_nsearch)
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 */
{
return __libc_res_nsearch(statp, name, class, type, answer,
anslen, NULL, NULL, NULL, NULL);
}
libresolv_hidden_def (res_nsearch)
/*
* Perform a call on res_query on the concatenation of name and domain,
* removing a trailing dot from name if domain is NULL.
*/
static int
__libc_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 */
u_char **answerp,
u_char **answerp2,
int *nanswerp2,
int *resplen2)
{
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 (__libc_res_nquery(statp, longname, class, type, answer,
anslen, answerp, answerp2, nanswerp2,
resplen2));
}
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 */
{
return __libc_res_nquerydomain(statp, name, domain, class, type,
answer, anslen, NULL, NULL, NULL, NULL);
}
libresolv_hidden_def (res_nquerydomain)
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(*cp1); ++cp1)
;
if (!*cp1)
break;
*cp1 = '\0';
if (ns_samename(buf, name) == 1) {
while (isspace(*++cp1))
;
if (!*cp1)
break;
for (cp2 = cp1 + 1; *cp2 && !isspace(*cp2); ++cp2)
;
*cp2 = '\0';
strncpy(dst, cp1, siz - 1);
dst[siz - 1] = '\0';
fclose(fp);
return (dst);
}
}
fclose(fp);
return (NULL);
}
libresolv_hidden_def (res_hostalias)