freebsd-dev/lib/libc/net/getnetbydns.c
Jacques Vidrine 2e4dbbaa93 When using res_send/res_query/res_search, the caller must either
insure enough space is available for the response, or be prepared
to resize the buffer and retry as necessary.

Do the conservative thing and make sure enough space is available.

Reviewed by:	silence on freebsd-audit
2002-09-13 20:31:29 +00:00

324 lines
9.0 KiB
C

/*-
* Copyright (c) 1985, 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--
*/
/* Portions Copyright (c) 1993 Carlos Leandro and Rui Salgueiro
* Dep. Matematica Universidade de Coimbra, Portugal, Europe
*
* 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.
*/
#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)gethostnamadr.c 8.1 (Berkeley) 6/4/93";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <arpa/nameser.h>
#include <stdio.h>
#include <netdb.h>
#include <resolv.h>
#include <ctype.h>
#include <string.h>
#include <unistd.h>
#include <syslog.h>
#include <stdarg.h>
#include <nsswitch.h>
#include "res_config.h"
extern int h_errno;
#define BYADDR 0
#define BYNAME 1
#define MAXALIASES 35
#define MAXPACKET 65536
typedef union {
HEADER hdr;
u_char buf[MAXPACKET];
} querybuf;
typedef union {
long al;
char ac;
} align;
static struct netent *
getnetanswer(answer, anslen, net_i)
querybuf *answer;
int anslen;
int net_i;
{
HEADER *hp;
u_char *cp;
int n;
u_char *eom;
int type, class, ancount, qdcount, haveanswer, i, nchar;
char aux1[MAXHOSTNAMELEN], aux2[MAXHOSTNAMELEN], ans[MAXHOSTNAMELEN];
char *in, *st, *pauxt, *bp, *ep, **ap;
char *paux1 = &aux1[0], *paux2 = &aux2[0], flag = 0;
static struct netent net_entry;
static char *net_aliases[MAXALIASES], netbuf[PACKETSZ];
/*
* find first satisfactory answer
*
* answer --> +------------+ ( MESSAGE )
* | Header |
* +------------+
* | Question | the question for the name server
* +------------+
* | Answer | RRs answering the question
* +------------+
* | Authority | RRs pointing toward an authority
* | Additional | RRs holding additional information
* +------------+
*/
eom = answer->buf + anslen;
hp = &answer->hdr;
ancount = ntohs(hp->ancount); /* #/records in the answer section */
qdcount = ntohs(hp->qdcount); /* #/entries in the question section */
bp = netbuf;
ep = netbuf + sizeof(netbuf);
cp = answer->buf + HFIXEDSZ;
if (!qdcount) {
if (hp->aa)
h_errno = HOST_NOT_FOUND;
else
h_errno = TRY_AGAIN;
return (NULL);
}
while (qdcount-- > 0)
cp += __dn_skipname(cp, eom) + QFIXEDSZ;
ap = net_aliases;
*ap = NULL;
net_entry.n_aliases = net_aliases;
haveanswer = 0;
while (--ancount >= 0 && cp < eom) {
n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
if ((n < 0) || !res_dnok(bp))
break;
cp += n;
ans[0] = '\0';
(void)strncpy(&ans[0], bp, sizeof(ans) - 1);
ans[sizeof(ans) - 1] = '\0';
GETSHORT(type, cp);
GETSHORT(class, cp);
cp += INT32SZ; /* TTL */
GETSHORT(n, cp);
if (class == C_IN && type == T_PTR) {
n = dn_expand(answer->buf, eom, cp, bp, ep - bp);
if ((n < 0) || !res_hnok(bp)) {
cp += n;
return (NULL);
}
cp += n;
*ap++ = bp;
n = strlen(bp) + 1;
bp += n;
net_entry.n_addrtype =
(class == C_IN) ? AF_INET : AF_UNSPEC;
haveanswer++;
}
}
if (haveanswer) {
*ap = NULL;
switch (net_i) {
case BYADDR:
net_entry.n_name = *net_entry.n_aliases;
net_entry.n_net = 0L;
break;
case BYNAME:
in = *net_entry.n_aliases;
net_entry.n_name = &ans[0];
aux2[0] = '\0';
for (i = 0; i < 4; i++) {
for (st = in, nchar = 0;
*st != '.';
st++, nchar++)
;
if (nchar != 1 || *in != '0' || flag) {
flag = 1;
(void)strncpy(paux1,
(i==0) ? in : in-1,
(i==0) ?nchar : nchar+1);
paux1[(i==0) ? nchar : nchar+1] = '\0';
pauxt = paux2;
paux2 = strcat(paux1, paux2);
paux1 = pauxt;
}
in = ++st;
}
net_entry.n_net = inet_network(paux2);
break;
}
net_entry.n_aliases++;
return (&net_entry);
}
h_errno = TRY_AGAIN;
return (NULL);
}
int
_dns_getnetbyaddr(void *rval, void *cb_data, va_list ap)
{
unsigned long net;
int net_type;
unsigned int netbr[4];
int nn, anslen;
querybuf buf;
char qbuf[MAXDNAME];
unsigned long net2;
struct netent *net_entry;
net = va_arg(ap, unsigned long);
net_type = va_arg(ap, int);
*(struct netent **)rval = NULL;
if (net_type != AF_INET)
return NS_UNAVAIL;
for (nn = 4, net2 = net; net2; net2 >>= 8)
netbr[--nn] = net2 & 0xff;
switch (nn) {
case 3: /* Class A */
sprintf(qbuf, "0.0.0.%u.in-addr.arpa", netbr[3]);
break;
case 2: /* Class B */
sprintf(qbuf, "0.0.%u.%u.in-addr.arpa", netbr[3], netbr[2]);
break;
case 1: /* Class C */
sprintf(qbuf, "0.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
netbr[1]);
break;
case 0: /* Class D - E */
sprintf(qbuf, "%u.%u.%u.%u.in-addr.arpa", netbr[3], netbr[2],
netbr[1], netbr[0]);
break;
}
anslen = res_query(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
if (anslen < 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf("res_query failed\n");
#endif
return NS_UNAVAIL;
}
net_entry = getnetanswer(&buf, anslen, BYADDR);
if (net_entry) {
unsigned u_net = net; /* maybe net should be unsigned ? */
/* Strip trailing zeros */
while ((u_net & 0xff) == 0 && u_net != 0)
u_net >>= 8;
net_entry->n_net = u_net;
*(struct netent **)rval = net_entry;
return NS_SUCCESS;
}
return NS_NOTFOUND;
}
int
_dns_getnetbyname(void *rval, void *cb_data, va_list ap)
{
const char *net;
int anslen;
querybuf buf;
char qbuf[MAXDNAME];
net = va_arg(ap, const char *);
*(struct netent**)rval = NULL;
if ((_res.options & RES_INIT) == 0 && res_init() == -1) {
h_errno = NETDB_INTERNAL;
return NS_UNAVAIL;
}
strncpy(qbuf, net, sizeof(qbuf) - 1);
qbuf[sizeof(qbuf) - 1] = '\0';
anslen = res_search(qbuf, C_IN, T_PTR, (u_char *)&buf, sizeof(buf));
if (anslen < 0) {
#ifdef DEBUG
if (_res.options & RES_DEBUG)
printf("res_query failed\n");
#endif
return NS_UNAVAIL;
}
*(struct netent**)rval = getnetanswer(&buf, anslen, BYNAME);
return (*(struct netent**)rval != NULL) ? NS_SUCCESS : NS_NOTFOUND;
}
void
_setnetdnsent(stayopen)
int stayopen;
{
if (stayopen)
_res.options |= RES_STAYOPEN | RES_USEVC;
}
void
_endnetdnsent()
{
_res.options &= ~(RES_STAYOPEN | RES_USEVC);
res_close();
}