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freebsd-dev/lib/libc/nameser/ns_name.c
Cy Schubert 4effc02129 Bounds check again after advancing cp, otherwise we have a possible 
heap buffer overflow. This was discovered by a Google fuzzer test.
This can lead to remote denial of service. User interaction and
execution privileges are not a prerequisite for exploitation.

Reported by:	enh at Google, to FreeBSD by maya@NetBSD.org
Obtained from:	enh at Google
See also:	NetBSD ns_name.c r1.12
Reviewed by:	delphij, ume
MFC after:	3 days
	https://android-review.googlesource.com/c/platform/bionic/+/1093130
Differential Revision:	https://reviews.freebsd.org/D21523
2019-09-05 19:35:30 +00:00

1159 lines
25 KiB
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/*-
* SPDX-License-Identifier: ISC
*
* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
* 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.
*/
#ifndef lint
static const char rcsid[] = "$Id: ns_name.c,v 1.11 2009/01/23 19:59:16 each Exp $";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "port_before.h"
#include <sys/types.h>
#include <netinet/in.h>
#include <arpa/nameser.h>
#include <errno.h>
#include <resolv.h>
#include <string.h>
#include <ctype.h>
#include <stdlib.h>
#include <limits.h>
#include "port_after.h"
#ifdef SPRINTF_CHAR
# define SPRINTF(x) strlen(sprintf/**/x)
#else
# define SPRINTF(x) ((size_t)sprintf x)
#endif
#define NS_TYPE_ELT 0x40 /*%< EDNS0 extended label type */
#define DNS_LABELTYPE_BITSTRING 0x41
/* Data. */
static const char digits[] = "0123456789";
static const char digitvalue[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*16*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, -1, -1, -1, -1, -1, -1, /*64*/
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
};
/* Forward. */
static int special(int);
static int printable(int);
static int dn_find(const u_char *, const u_char *,
const u_char * const *,
const u_char * const *);
static int encode_bitsring(const char **, const char *,
unsigned char **, unsigned char **,
unsigned const char *);
static int labellen(const u_char *);
static int decode_bitstring(const unsigned char **,
char *, const char *);
/* Public. */
/*%
* Convert an encoded domain name to printable ascii as per RFC1035.
* return:
*\li Number of bytes written to buffer, or -1 (with errno set)
*
* notes:
*\li The root is returned as "."
*\li All other domains are returned in non absolute form
*/
int
ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
{
const u_char *cp;
char *dn, *eom;
u_char c;
u_int n;
int l;
cp = src;
dn = dst;
eom = dst + dstsiz;
while ((n = *cp++) != 0) {
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Some kind of compression pointer. */
errno = EMSGSIZE;
return (-1);
}
if (dn != dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if ((l = labellen(cp - 1)) < 0) {
errno = EMSGSIZE; /*%< XXX */
return (-1);
}
if (dn + l >= eom) {
errno = EMSGSIZE;
return (-1);
}
if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
int m;
if (n != DNS_LABELTYPE_BITSTRING) {
/* XXX: labellen should reject this case */
errno = EINVAL;
return (-1);
}
if ((m = decode_bitstring(&cp, dn, eom)) < 0)
{
errno = EMSGSIZE;
return (-1);
}
dn += m;
continue;
}
for ((void)NULL; l > 0; l--) {
c = *cp++;
if (special(c)) {
if (dn + 1 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = (char)c;
} else if (!printable(c)) {
if (dn + 3 >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\\';
*dn++ = digits[c / 100];
*dn++ = digits[(c % 100) / 10];
*dn++ = digits[c % 10];
} else {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = (char)c;
}
}
}
if (dn == dst) {
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '.';
}
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
*dn++ = '\0';
return (dn - dst);
}
/*%
* Convert a ascii string into an encoded domain name as per RFC1035.
*
* return:
*
*\li -1 if it fails
*\li 1 if string was fully qualified
*\li 0 is string was not fully qualified
*
* notes:
*\li Enforces label and domain length limits.
*/
int
ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
return (ns_name_pton2(src, dst, dstsiz, NULL));
}
/*
* ns_name_pton2(src, dst, dstsiz, *dstlen)
* Convert a ascii string into an encoded domain name as per RFC1035.
* return:
* -1 if it fails
* 1 if string was fully qualified
* 0 is string was not fully qualified
* side effects:
* fills in *dstlen (if non-NULL)
* notes:
* Enforces label and domain length limits.
*/
int
ns_name_pton2(const char *src, u_char *dst, size_t dstsiz, size_t *dstlen) {
u_char *label, *bp, *eom;
int c, n, escaped, e = 0;
char *cp;
escaped = 0;
bp = dst;
eom = dst + dstsiz;
label = bp++;
while ((c = *src++) != 0) {
if (escaped) {
if (c == '[') { /*%< start a bit string label */
if ((cp = strchr(src, ']')) == NULL) {
errno = EINVAL; /*%< ??? */
return (-1);
}
if ((e = encode_bitsring(&src, cp + 2,
&label, &bp, eom))
!= 0) {
errno = e;
return (-1);
}
escaped = 0;
label = bp++;
if ((c = *src++) == 0)
goto done;
else if (c != '.') {
errno = EINVAL;
return (-1);
}
continue;
}
else if ((cp = strchr(digits, c)) != NULL) {
n = (cp - digits) * 100;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits) * 10;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
errno = EMSGSIZE;
return (-1);
}
n += (cp - digits);
if (n > 255) {
errno = EMSGSIZE;
return (-1);
}
c = n;
}
escaped = 0;
} else if (c == '\\') {
escaped = 1;
continue;
} else if (c == '.') {
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
errno = EMSGSIZE;
return (-1);
}
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
/* Fully qualified ? */
if (*src == '\0') {
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = '\0';
}
if ((bp - dst) > MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
if (dstlen != NULL)
*dstlen = (bp - dst);
return (1);
}
if (c == 0 || *src == '.') {
errno = EMSGSIZE;
return (-1);
}
label = bp++;
continue;
}
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = (u_char)c;
}
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
errno = EMSGSIZE;
return (-1);
}
done:
if (label >= eom) {
errno = EMSGSIZE;
return (-1);
}
*label = c;
if (c != 0) {
if (bp >= eom) {
errno = EMSGSIZE;
return (-1);
}
*bp++ = 0;
}
if ((bp - dst) > MAXCDNAME) { /*%< src too big */
errno = EMSGSIZE;
return (-1);
}
if (dstlen != NULL)
*dstlen = (bp - dst);
return (0);
}
/*%
* Convert a network strings labels into all lowercase.
*
* return:
*\li Number of bytes written to buffer, or -1 (with errno set)
*
* notes:
*\li Enforces label and domain length limits.
*/
int
ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
{
const u_char *cp;
u_char *dn, *eom;
u_char c;
u_int n;
int l;
cp = src;
dn = dst;
eom = dst + dstsiz;
if (dn >= eom) {
errno = EMSGSIZE;
return (-1);
}
while ((n = *cp++) != 0) {
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Some kind of compression pointer. */
errno = EMSGSIZE;
return (-1);
}
*dn++ = n;
if ((l = labellen(cp - 1)) < 0) {
errno = EMSGSIZE;
return (-1);
}
if (dn + l >= eom) {
errno = EMSGSIZE;
return (-1);
}
for ((void)NULL; l > 0; l--) {
c = *cp++;
if (isascii(c) && isupper(c))
*dn++ = tolower(c);
else
*dn++ = c;
}
}
*dn++ = '\0';
return (dn - dst);
}
/*%
* Unpack a domain name from a message, source may be compressed.
*
* return:
*\li -1 if it fails, or consumed octets if it succeeds.
*/
int
ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
u_char *dst, size_t dstsiz)
{
return (ns_name_unpack2(msg, eom, src, dst, dstsiz, NULL));
}
/*
* ns_name_unpack2(msg, eom, src, dst, dstsiz, *dstlen)
* Unpack a domain name from a message, source may be compressed.
* return:
* -1 if it fails, or consumed octets if it succeeds.
* side effect:
* fills in *dstlen (if non-NULL).
*/
int
ns_name_unpack2(const u_char *msg, const u_char *eom, const u_char *src,
u_char *dst, size_t dstsiz, size_t *dstlen)
{
const u_char *srcp, *dstlim;
u_char *dstp;
int n, len, checked, l;
len = -1;
checked = 0;
dstp = dst;
srcp = src;
dstlim = dst + dstsiz;
if (srcp < msg || srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
/* Fetch next label in domain name. */
while ((n = *srcp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0:
case NS_TYPE_ELT:
/* Limit checks. */
if ((l = labellen(srcp - 1)) < 0) {
errno = EMSGSIZE;
return (-1);
}
if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
errno = EMSGSIZE;
return (-1);
}
checked += l + 1;
*dstp++ = n;
memcpy(dstp, srcp, l);
dstp += l;
srcp += l;
break;
case NS_CMPRSFLGS:
if (srcp >= eom) {
errno = EMSGSIZE;
return (-1);
}
if (len < 0)
len = srcp - src + 1;
l = ((n & 0x3f) << 8) | (*srcp & 0xff);
if (l >= eom - msg) { /*%< Out of range. */
errno = EMSGSIZE;
return (-1);
}
srcp = msg + l;
checked += 2;
/*
* Check for loops in the compressed name;
* if we've looked at the whole message,
* there must be a loop.
*/
if (checked >= eom - msg) {
errno = EMSGSIZE;
return (-1);
}
break;
default:
errno = EMSGSIZE;
return (-1); /*%< flag error */
}
}
*dstp++ = 0;
if (dstlen != NULL)
*dstlen = dstp - dst;
if (len < 0)
len = srcp - src;
return (len);
}
/*%
* Pack domain name 'domain' into 'comp_dn'.
*
* return:
*\li Size of the compressed name, or -1.
*
* notes:
*\li 'dnptrs' is an array of pointers to previous compressed names.
*\li dnptrs[0] is a pointer to the beginning of the message. The array
* ends with NULL.
*\li 'lastdnptr' is a pointer to the end of the array pointed to
* by 'dnptrs'.
*
* Side effects:
*\li The list of pointers in dnptrs is updated for labels inserted into
* the message as we compress the name. If 'dnptr' is NULL, we don't
* try to compress names. If 'lastdnptr' is NULL, we don't update the
* list.
*/
int
ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
const u_char **dnptrs, const u_char **lastdnptr)
{
u_char *dstp;
const u_char **cpp, **lpp, *eob, *msg;
const u_char *srcp;
int n, l, first = 1;
srcp = src;
dstp = dst;
eob = dstp + dstsiz;
lpp = cpp = NULL;
if (dnptrs != NULL) {
if ((msg = *dnptrs++) != NULL) {
for (cpp = dnptrs; *cpp != NULL; cpp++)
(void)NULL;
lpp = cpp; /*%< end of list to search */
}
} else
msg = NULL;
/* make sure the domain we are about to add is legal */
l = 0;
do {
int l0;
n = *srcp;
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
errno = EMSGSIZE;
return (-1);
}
if ((l0 = labellen(srcp)) < 0) {
errno = EINVAL;
return (-1);
}
l += l0 + 1;
if (l > MAXCDNAME) {
errno = EMSGSIZE;
return (-1);
}
srcp += l0 + 1;
} while (n != 0);
/* from here on we need to reset compression pointer array on error */
srcp = src;
do {
/* Look to see if we can use pointers. */
n = *srcp;
if (n != 0 && msg != NULL) {
l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
(const u_char * const *)lpp);
if (l >= 0) {
if (dstp + 1 >= eob) {
goto cleanup;
}
*dstp++ = (l >> 8) | NS_CMPRSFLGS;
*dstp++ = l % 256;
return (dstp - dst);
}
/* Not found, save it. */
if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
(dstp - msg) < 0x4000 && first) {
*cpp++ = dstp;
*cpp = NULL;
first = 0;
}
}
/* copy label to buffer */
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Should not happen. */
goto cleanup;
}
n = labellen(srcp);
if (dstp + 1 + n >= eob) {
goto cleanup;
}
memcpy(dstp, srcp, n + 1);
srcp += n + 1;
dstp += n + 1;
} while (n != 0);
if (dstp > eob) {
cleanup:
if (msg != NULL)
*lpp = NULL;
errno = EMSGSIZE;
return (-1);
}
return (dstp - dst);
}
/*%
* Expand compressed domain name to presentation format.
*
* return:
*\li Number of bytes read out of `src', or -1 (with errno set).
*
* note:
*\li Root domain returns as "." not "".
*/
int
ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
char *dst, size_t dstsiz)
{
u_char tmp[NS_MAXCDNAME];
int n;
if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
return (-1);
if (ns_name_ntop(tmp, dst, dstsiz) == -1)
return (-1);
return (n);
}
/*%
* Compress a domain name into wire format, using compression pointers.
*
* return:
*\li Number of bytes consumed in `dst' or -1 (with errno set).
*
* notes:
*\li 'dnptrs' is an array of pointers to previous compressed names.
*\li dnptrs[0] is a pointer to the beginning of the message.
*\li The list ends with NULL. 'lastdnptr' is a pointer to the end of the
* array pointed to by 'dnptrs'. Side effect is to update the list of
* pointers for labels inserted into the message as we compress the name.
*\li If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
* is NULL, we don't update the list.
*/
int
ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
const u_char **dnptrs, const u_char **lastdnptr)
{
u_char tmp[NS_MAXCDNAME];
if (ns_name_pton(src, tmp, sizeof tmp) == -1)
return (-1);
return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
}
/*%
* Reset dnptrs so that there are no active references to pointers at or
* after src.
*/
void
ns_name_rollback(const u_char *src, const u_char **dnptrs,
const u_char **lastdnptr)
{
while (dnptrs < lastdnptr && *dnptrs != NULL) {
if (*dnptrs >= src) {
*dnptrs = NULL;
break;
}
dnptrs++;
}
}
/*%
* Advance *ptrptr to skip over the compressed name it points at.
*
* return:
*\li 0 on success, -1 (with errno set) on failure.
*/
int
ns_name_skip(const u_char **ptrptr, const u_char *eom)
{
const u_char *cp;
u_int n;
int l = 0;
cp = *ptrptr;
while (cp < eom && (n = *cp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0: /*%< normal case, n == len */
cp += n;
continue;
case NS_TYPE_ELT: /*%< EDNS0 extended label */
if (cp < eom && (l = labellen(cp - 1)) < 0) {
errno = EMSGSIZE; /*%< XXX */
return (-1);
}
cp += l;
continue;
case NS_CMPRSFLGS: /*%< indirection */
cp++;
break;
default: /*%< illegal type */
errno = EMSGSIZE;
return (-1);
}
break;
}
if (cp > eom) {
errno = EMSGSIZE;
return (-1);
}
*ptrptr = cp;
return (0);
}
/* Find the number of octets an nname takes up, including the root label.
* (This is basically ns_name_skip() without compression-pointer support.)
* ((NOTE: can only return zero if passed-in namesiz argument is zero.))
*/
ssize_t
ns_name_length(ns_nname_ct nname, size_t namesiz) {
ns_nname_ct orig = nname;
u_int n;
while (namesiz-- > 0 && (n = *nname++) != 0) {
if ((n & NS_CMPRSFLGS) != 0) {
errno = EISDIR;
return (-1);
}
if (n > namesiz) {
errno = EMSGSIZE;
return (-1);
}
nname += n;
namesiz -= n;
}
return (nname - orig);
}
/* Compare two nname's for equality. Return -1 on error (setting errno).
*/
int
ns_name_eq(ns_nname_ct a, size_t as, ns_nname_ct b, size_t bs) {
ns_nname_ct ae = a + as, be = b + bs;
int ac, bc;
while (ac = *a, bc = *b, ac != 0 && bc != 0) {
if ((ac & NS_CMPRSFLGS) != 0 || (bc & NS_CMPRSFLGS) != 0) {
errno = EISDIR;
return (-1);
}
if (a + ac >= ae || b + bc >= be) {
errno = EMSGSIZE;
return (-1);
}
if (ac != bc || strncasecmp((const char *) ++a,
(const char *) ++b, ac) != 0)
return (0);
a += ac, b += bc;
}
return (ac == 0 && bc == 0);
}
/* Is domain "A" owned by (at or below) domain "B"?
*/
int
ns_name_owned(ns_namemap_ct a, int an, ns_namemap_ct b, int bn) {
/* If A is shorter, it cannot be owned by B. */
if (an < bn)
return (0);
/* If they are unequal before the length of the shorter, A cannot... */
while (bn > 0) {
if (a->len != b->len ||
strncasecmp((const char *) a->base,
(const char *) b->base, a->len) != 0)
return (0);
a++, an--;
b++, bn--;
}
/* A might be longer or not, but either way, B owns it. */
return (1);
}
/* Build an array of <base,len> tuples from an nname, top-down order.
* Return the number of tuples (labels) thus discovered.
*/
int
ns_name_map(ns_nname_ct nname, size_t namelen, ns_namemap_t map, int mapsize) {
u_int n;
int l;
n = *nname++;
namelen--;
/* Root zone? */
if (n == 0) {
/* Extra data follows name? */
if (namelen > 0) {
errno = EMSGSIZE;
return (-1);
}
return (0);
}
/* Compression pointer? */
if ((n & NS_CMPRSFLGS) != 0) {
errno = EISDIR;
return (-1);
}
/* Label too long? */
if (n > namelen) {
errno = EMSGSIZE;
return (-1);
}
/* Recurse to get rest of name done first. */
l = ns_name_map(nname + n, namelen - n, map, mapsize);
if (l < 0)
return (-1);
/* Too many labels? */
if (l >= mapsize) {
errno = ENAMETOOLONG;
return (-1);
}
/* We're on our way back up-stack, store current map data. */
map[l].base = nname;
map[l].len = n;
return (l + 1);
}
/* Count the labels in a domain name. Root counts, so COM. has two. This
* is to make the result comparable to the result of ns_name_map().
*/
int
ns_name_labels(ns_nname_ct nname, size_t namesiz) {
int ret = 0;
u_int n;
while (namesiz-- > 0 && (n = *nname++) != 0) {
if ((n & NS_CMPRSFLGS) != 0) {
errno = EISDIR;
return (-1);
}
if (n > namesiz) {
errno = EMSGSIZE;
return (-1);
}
nname += n;
namesiz -= n;
ret++;
}
return (ret + 1);
}
/* Private. */
/*%
* Thinking in noninternationalized USASCII (per the DNS spec),
* is this characted special ("in need of quoting") ?
*
* return:
*\li boolean.
*/
static int
special(int ch) {
switch (ch) {
case 0x22: /*%< '"' */
case 0x2E: /*%< '.' */
case 0x3B: /*%< ';' */
case 0x5C: /*%< '\\' */
case 0x28: /*%< '(' */
case 0x29: /*%< ')' */
/* Special modifiers in zone files. */
case 0x40: /*%< '@' */
case 0x24: /*%< '$' */
return (1);
default:
return (0);
}
}
/*%
* Thinking in noninternationalized USASCII (per the DNS spec),
* is this character visible and not a space when printed ?
*
* return:
*\li boolean.
*/
static int
printable(int ch) {
return (ch > 0x20 && ch < 0x7f);
}
/*%
* Thinking in noninternationalized USASCII (per the DNS spec),
* convert this character to lower case if it's upper case.
*/
static int
mklower(int ch) {
if (ch >= 0x41 && ch <= 0x5A)
return (ch + 0x20);
return (ch);
}
/*%
* Search for the counted-label name in an array of compressed names.
*
* return:
*\li offset from msg if found, or -1.
*
* notes:
*\li dnptrs is the pointer to the first name on the list,
*\li not the pointer to the start of the message.
*/
static int
dn_find(const u_char *domain, const u_char *msg,
const u_char * const *dnptrs,
const u_char * const *lastdnptr)
{
const u_char *dn, *cp, *sp;
const u_char * const *cpp;
u_int n;
for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
sp = *cpp;
/*
* terminate search on:
* root label
* compression pointer
* unusable offset
*/
while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
(sp - msg) < 0x4000) {
dn = domain;
cp = sp;
while ((n = *cp++) != 0) {
/*
* check for indirection
*/
switch (n & NS_CMPRSFLGS) {
case 0: /*%< normal case, n == len */
n = labellen(cp - 1); /*%< XXX */
if (n != *dn++)
goto next;
for ((void)NULL; n > 0; n--)
if (mklower(*dn++) !=
mklower(*cp++))
goto next;
/* Is next root for both ? */
if (*dn == '\0' && *cp == '\0')
return (sp - msg);
if (*dn)
continue;
goto next;
case NS_CMPRSFLGS: /*%< indirection */
cp = msg + (((n & 0x3f) << 8) | *cp);
break;
default: /*%< illegal type */
errno = EMSGSIZE;
return (-1);
}
}
next: ;
sp += *sp + 1;
}
}
errno = ENOENT;
return (-1);
}
static int
decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
{
const unsigned char *cp = *cpp;
char *beg = dn, tc;
int b, blen, plen, i;
if ((blen = (*cp & 0xff)) == 0)
blen = 256;
plen = (blen + 3) / 4;
plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
if (dn + plen >= eom)
return (-1);
cp++;
i = SPRINTF((dn, "\\[x"));
if (i < 0)
return (-1);
dn += i;
for (b = blen; b > 7; b -= 8, cp++) {
i = SPRINTF((dn, "%02x", *cp & 0xff));
if (i < 0)
return (-1);
dn += i;
}
if (b > 4) {
tc = *cp++;
i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
if (i < 0)
return (-1);
dn += i;
} else if (b > 0) {
tc = *cp++;
i = SPRINTF((dn, "%1x",
((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
if (i < 0)
return (-1);
dn += i;
}
i = SPRINTF((dn, "/%d]", blen));
if (i < 0)
return (-1);
dn += i;
*cpp = cp;
return (dn - beg);
}
static int
encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
unsigned char ** dst, unsigned const char *eom)
{
int afterslash = 0;
const char *cp = *bp;
unsigned char *tp;
char c;
const char *beg_blen;
char *end_blen = NULL;
int value = 0, count = 0, tbcount = 0, blen = 0;
beg_blen = end_blen = NULL;
/* a bitstring must contain at least 2 characters */
if (end - cp < 2)
return (EINVAL);
/* XXX: currently, only hex strings are supported */
if (*cp++ != 'x')
return (EINVAL);
if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
return (EINVAL);
for (tp = *dst + 1; cp < end && tp < eom; cp++) {
switch((c = *cp)) {
case ']': /*%< end of the bitstring */
if (afterslash) {
if (beg_blen == NULL)
return (EINVAL);
blen = (int)strtol(beg_blen, &end_blen, 10);
if (*end_blen != ']')
return (EINVAL);
}
if (count)
*tp++ = ((value << 4) & 0xff);
cp++; /*%< skip ']' */
goto done;
case '/':
afterslash = 1;
break;
default:
if (afterslash) {
if (!isdigit(c&0xff))
return (EINVAL);
if (beg_blen == NULL) {
if (c == '0') {
/* blen never begings with 0 */
return (EINVAL);
}
beg_blen = cp;
}
} else {
if (!isxdigit(c&0xff))
return (EINVAL);
value <<= 4;
value += digitvalue[(int)c];
count += 4;
tbcount += 4;
if (tbcount > 256)
return (EINVAL);
if (count == 8) {
*tp++ = value;
count = 0;
}
}
break;
}
}
done:
if (cp >= end || tp >= eom)
return (EMSGSIZE);
/*
* bit length validation:
* If a <length> is present, the number of digits in the <bit-data>
* MUST be just sufficient to contain the number of bits specified
* by the <length>. If there are insignificant bits in a final
* hexadecimal or octal digit, they MUST be zero.
* RFC2673, Section 3.2.
*/
if (blen > 0) {
int traillen;
if (((blen + 3) & ~3) != tbcount)
return (EINVAL);
traillen = tbcount - blen; /*%< between 0 and 3 */
if (((value << (8 - traillen)) & 0xff) != 0)
return (EINVAL);
}
else
blen = tbcount;
if (blen == 256)
blen = 0;
/* encode the type and the significant bit fields */
**labelp = DNS_LABELTYPE_BITSTRING;
**dst = blen;
*bp = cp;
*dst = tp;
return (0);
}
static int
labellen(const u_char *lp)
{
int bitlen;
u_char l = *lp;
if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* should be avoided by the caller */
return (-1);
}
if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
if (l == DNS_LABELTYPE_BITSTRING) {
if ((bitlen = *(lp + 1)) == 0)
bitlen = 256;
return ((bitlen + 7 ) / 8 + 1);
}
return (-1); /*%< unknwon ELT */
}
return (l);
}
/*! \file */
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