glibc/resolv/ns_name_skip.c
Florian Weimer cff2c78c51 resolv: Move ns_name_skip to its own file and into libc (bug 28091)
And reformat to GNU style.  Avoid out-of-bounds pointer arithmetic.
This also results in a fix of bug 28091 due to the additional packet
length checks.

The symbol was moved using scripts/move-symbol-to-libc.py.

Reviewed-by: Carlos O'Donell <carlos@systemhalted.org>
2021-07-19 07:56:13 +02:00

71 lines
2.3 KiB
C

/* Skip over a (potentially compressed) domain name in wire format.
* 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 <arpa/nameser.h>
#include <errno.h>
#include <shlib-compat.h>
/* Advances *PTRPTR to skip over the compressed name it points at.
Returns 0 on success, -1 (with errno set) on failure. */
int
___ns_name_skip (const unsigned char **ptrptr, const unsigned char *eom)
{
const unsigned char *cp;
unsigned int n;
cp = *ptrptr;
while (cp < eom)
{
n = *cp++;
if (n == 0)
{
/* End of domain name without indirection. */
*ptrptr = cp;
return 0;
}
/* Check for indirection. */
switch (n & NS_CMPRSFLGS)
{
case 0: /* Normal case, n == len. */
if (eom - cp < n)
goto malformed;
cp += n;
break;
case NS_CMPRSFLGS: /* Indirection. */
if (cp == eom)
/* No room for second indirection byte. */
goto malformed;
*ptrptr = cp + 1;
return 0;
default: /* Illegal type. */
goto malformed;
}
}
malformed:
__set_errno (EMSGSIZE);
return -1;
}
versioned_symbol (libc, ___ns_name_skip, ns_name_skip, GLIBC_2_34);
versioned_symbol (libc, ___ns_name_skip, __ns_name_skip, GLIBC_PRIVATE);
libc_hidden_ver (___ns_name_skip, __ns_name_skip)
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
compat_symbol (libresolv, ___ns_name_skip, ns_name_skip, GLIBC_2_9);
#endif