116 lines
3.5 KiB
C
116 lines
3.5 KiB
C
/* De-compressing DNS domain names into binary-encoded uncompressed name.
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* Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
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* Copyright (c) 1996,1999 by Internet Software Consortium.
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
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* OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <arpa/nameser.h>
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#include <errno.h>
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#include <shlib-compat.h>
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#include <stddef.h>
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#include <string.h>
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/* Unpack a domain name from a message, source may be compressed.
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Returns -1 if it fails, or consumed octets if it succeeds. */
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int
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___ns_name_unpack (const unsigned char *msg, const unsigned char *eom,
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const unsigned char *src, unsigned char *dst, size_t dstsiz)
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{
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const unsigned char *srcp, *dstlim;
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unsigned char *dstp;
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int n, len, checked;
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len = -1;
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checked = 0;
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dstp = dst;
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srcp = src;
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dstlim = dst + dstsiz;
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if (srcp < msg || srcp >= eom)
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{
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__set_errno (EMSGSIZE);
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return -1;
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}
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/* Fetch next label in domain name. */
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while ((n = *srcp++) != 0)
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{
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/* Check for indirection. */
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switch (n & NS_CMPRSFLGS)
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{
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case 0:
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/* Limit checks. */
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if (n >= 64)
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{
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__set_errno (EMSGSIZE);
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return -1;
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}
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/* NB: n + 1 and >= to cover the *dstp = '\0' assignment
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below. */
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if (n + 1 >= dstlim - dstp || n >= eom - srcp)
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{
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__set_errno (EMSGSIZE);
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return -1;
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}
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checked += n + 1;
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*dstp++ = n;
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memcpy (dstp, srcp, n);
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dstp += n;
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srcp += n;
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break;
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case NS_CMPRSFLGS:
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if (srcp >= eom)
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{
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__set_errno (EMSGSIZE);
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return -1;
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}
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if (len < 0)
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len = srcp - src + 1;
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{
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int target = ((n & 0x3f) << 8) | *srcp;
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if (target >= eom - msg)
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{
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/* Out of range. */
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__set_errno (EMSGSIZE);
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return -1;
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}
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srcp = msg + target;
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}
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checked += 2;
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/* Check for loops in the compressed name; if we've looked
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at the whole message, there must be a loop. */
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if (checked >= eom - msg)
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{
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__set_errno (EMSGSIZE);
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return -1;
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}
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break;
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default:
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__set_errno (EMSGSIZE);
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return -1;
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}
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}
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*dstp = '\0';
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if (len < 0)
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len = srcp - src;
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return len;
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}
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versioned_symbol (libc, ___ns_name_unpack, ns_name_unpack, GLIBC_2_34);
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versioned_symbol (libc, ___ns_name_unpack, __ns_name_unpack, GLIBC_PRIVATE);
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libc_hidden_ver (___ns_name_unpack, __ns_name_unpack)
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#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
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compat_symbol (libresolv, ___ns_name_unpack, ns_name_unpack, GLIBC_2_9);
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#endif
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