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/* De-compressing DNS domain names into binary-encoded uncompressed name.
* 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>
#include <stddef.h>
#include <string.h>
/* Unpack a domain name from a message, source may be compressed.
Returns -1 if it fails, or consumed octets if it succeeds. */
int
___ns_name_unpack (const unsigned char *msg, const unsigned char *eom,
const unsigned char *src, unsigned char *dst, size_t dstsiz)
{
const unsigned char *srcp, *dstlim;
unsigned char *dstp;
int n, len, checked;
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 (n >= 64)
{
__set_errno (EMSGSIZE);
return -1;
}
/* NB: n + 1 and >= to cover the *dstp = '\0' assignment
below. */
if (n + 1 >= dstlim - dstp || n >= eom - srcp)
{
__set_errno (EMSGSIZE);
return -1;
}
checked += n + 1;
*dstp++ = n;
memcpy (dstp, srcp, n);
dstp += n;
srcp += n;
break;
case NS_CMPRSFLGS:
if (srcp >= eom)
{
__set_errno (EMSGSIZE);
return -1;
}
if (len < 0)
len = srcp - src + 1;
{
int target = ((n & 0x3f) << 8) | *srcp;
if (target >= eom - msg)
{
/* Out of range. */
__set_errno (EMSGSIZE);
return -1;
}
srcp = msg + target;
}
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;
}
}
*dstp = '\0';
if (len < 0)
len = srcp - src;
return len;
}
versioned_symbol (libc, ___ns_name_unpack, ns_name_unpack, GLIBC_2_34);
versioned_symbol (libc, ___ns_name_unpack, __ns_name_unpack, GLIBC_PRIVATE);
libc_hidden_ver (___ns_name_unpack, __ns_name_unpack)
#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
compat_symbol (libresolv, ___ns_name_unpack, ns_name_unpack, GLIBC_2_9);
#endif
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