lib/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2025-11-03 20:53:13 +03:00
Code Activity
Files
23ea69a9d6e9ab28c66a232b767a800b04eaa938
glibc/resolv/ns_name.c
Florian Weimer c803cb9b24 resolv: Support an exactly sized buffer in ns_name_pack [BZ #21359] 
This bug did not affect name resolution because those functions
indirectly call ns_name_pack with a buffer which is always larger
than the generated query packet, even in the case of the
longest-possible domain name.
2017-04-13 11:56:28 +02:00

731 lines
15 KiB
C
Raw Blame History

/*
* 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.
*/
#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>
# define SPRINTF(x) ((size_t)sprintf x)
/* Data. */
static const char digits[] = "0123456789";
/* 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 labellen(const u_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. */
__set_errno (EMSGSIZE);
return (-1);
}
if (dn != dst) {
if (dn >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = '.';
}
if ((l = labellen(cp - 1)) < 0) {
__set_errno (EMSGSIZE);
return(-1);
}
if (dn + l >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
for ((void)NULL; l > 0; l--) {
c = *cp++;
if (special(c)) {
if (dn + 1 >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = '\\';
*dn++ = (char)c;
} else if (!printable(c)) {
if (dn + 3 >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = '\\';
*dn++ = digits[c / 100];
*dn++ = digits[(c % 100) / 10];
*dn++ = digits[c % 10];
} else {
if (dn >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = (char)c;
}
}
}
if (dn == dst) {
if (dn >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = '.';
}
if (dn >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = '\0';
return (dn - dst);
}
libresolv_hidden_def (ns_name_ntop)
strong_alias (ns_name_ntop, __ns_name_ntop)
/*%
* Convert an 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)
{
u_char *label, *bp, *eom;
int c, n, escaped;
char *cp;
escaped = 0;
bp = dst;
eom = dst + dstsiz;
label = bp++;
while ((c = *src++) != 0) {
if (escaped) {
if ((cp = strchr(digits, c)) != NULL) {
n = (cp - digits) * 100;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
__set_errno (EMSGSIZE);
return (-1);
}
n += (cp - digits) * 10;
if ((c = *src++) == 0 ||
(cp = strchr(digits, c)) == NULL) {
__set_errno (EMSGSIZE);
return (-1);
}
n += (cp - digits);
if (n > 255) {
__set_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. */
__set_errno (EMSGSIZE);
return (-1);
}
if (label >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*label = c;
/* Fully qualified ? */
if (*src == '\0') {
if (c != 0) {
if (bp >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*bp++ = '\0';
}
if ((bp - dst) > MAXCDNAME) {
__set_errno (EMSGSIZE);
return (-1);
}
return (1);
}
if (c == 0 || *src == '.') {
__set_errno (EMSGSIZE);
return (-1);
}
label = bp++;
continue;
}
if (bp >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*bp++ = (u_char)c;
}
c = (bp - label - 1);
if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
__set_errno (EMSGSIZE);
return (-1);
}
if (label >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*label = c;
if (c != 0) {
if (bp >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*bp++ = 0;
}
if ((bp - dst) > MAXCDNAME) { /*%< src too big */
__set_errno (EMSGSIZE);
return (-1);
}
return (0);
}
libresolv_hidden_def (ns_name_pton)
/*%
* 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) {
__set_errno (EMSGSIZE);
return (-1);
}
while ((n = *cp++) != 0) {
if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
/* Some kind of compression pointer. */
__set_errno (EMSGSIZE);
return (-1);
}
*dn++ = n;
if ((l = labellen(cp - 1)) < 0) {
__set_errno (EMSGSIZE);
return (-1);
}
if (dn + l >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
for ((void)NULL; l > 0; l--) {
c = *cp++;
if (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)
{
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) {
__set_errno (EMSGSIZE);
return (-1);
}
/* Fetch next label in domain name. */
while ((n = *srcp++) != 0) {
/* Check for indirection. */
switch (n & NS_CMPRSFLGS) {
case 0:
/* Limit checks. */
if ((l = labellen(srcp - 1)) < 0) {
__set_errno (EMSGSIZE);
return(-1);
}
if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
checked += l + 1;
*dstp++ = n;
memcpy(dstp, srcp, l);
dstp += l;
srcp += l;
break;
case NS_CMPRSFLGS:
if (srcp >= eom) {
__set_errno (EMSGSIZE);
return (-1);
}
if (len < 0)
len = srcp - src + 1;
srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
if (srcp < msg || srcp >= eom) { /*%< Out of range. */
__set_errno (EMSGSIZE);
return (-1);
}
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) {
__set_errno (EMSGSIZE);
return (-1);
}
break;
default:
__set_errno (EMSGSIZE);
return (-1); /*%< flag error */
}
}
*dstp = '\0';
if (len < 0)
len = srcp - src;
return (len);
}
libresolv_hidden_def (ns_name_unpack)
strong_alias (ns_name_unpack, __ns_name_unpack)
/*%
* 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) {
__set_errno (EMSGSIZE);
return (-1);
}
if ((l0 = labellen(srcp)) < 0) {
__set_errno (EINVAL);
return(-1);
}
l += l0 + 1;
if (l > MAXCDNAME) {
__set_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 (n + 1 > eob - dstp) {
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;
__set_errno (EMSGSIZE);
return (-1);
}
return (dstp - dst);
}
libresolv_hidden_def (ns_name_pack)
/*%
* 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);
}
libresolv_hidden_def (ns_name_uncompress)
/*%
* 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));
}
libresolv_hidden_def (ns_name_compress)
/*%
* 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;
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_CMPRSFLGS: /*%< indirection */
cp++;
break;
default: /*%< illegal type */
__set_errno (EMSGSIZE);
return (-1);
}
break;
}
if (cp > eom) {
__set_errno (EMSGSIZE);
return (-1);
}
*ptrptr = cp;
return (0);
}
libresolv_hidden_def (ns_name_skip)
/* Private. */
/*%
* Thinking in noninternationalized USASCII (per the DNS spec),
* is this character 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 */
__set_errno (EMSGSIZE);
return (-1);
}
}
next: ;
sp += *sp + 1;
}
}
__set_errno (ENOENT);
return (-1);
}
/* Return the length of the encoded label starting at LP, or -1 for
compression references and extended label types. */
static int
labellen (const unsigned char *lp)
{
if (*lp <= 63)
return *lp;
return -1;
}
/*! \file */
View Git Blame Copy Permalink