1/* Skip over a (potentially compressed) domain name in wire format.
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996,1999 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include <arpa/nameser.h>
19#include <errno.h>
20#include <shlib-compat.h>
21
22/* Advances *PTRPTR to skip over the compressed name it points at.
23 Returns 0 on success, -1 (with errno set) on failure. */
24int
25___ns_name_skip (const unsigned char **ptrptr, const unsigned char *eom)
26{
27 const unsigned char *cp;
28 unsigned int n;
29
30 cp = *ptrptr;
31 while (cp < eom)
32 {
33 n = *cp++;
34 if (n == 0)
35 {
36 /* End of domain name without indirection. */
37 *ptrptr = cp;
38 return 0;
39 }
40
41 /* Check for indirection. */
42 switch (n & NS_CMPRSFLGS)
43 {
44 case 0: /* Normal case, n == len. */
45 if (eom - cp < n)
46 goto malformed;
47 cp += n;
48 break;
49 case NS_CMPRSFLGS: /* Indirection. */
50 if (cp == eom)
51 /* No room for second indirection byte. */
52 goto malformed;
53 *ptrptr = cp + 1;
54 return 0;
55 default: /* Illegal type. */
56 goto malformed;
57 }
58 }
59
60 malformed:
61 __set_errno (EMSGSIZE);
62 return -1;
63}
64versioned_symbol (libc, ___ns_name_skip, ns_name_skip, GLIBC_2_34);
65versioned_symbol (libc, ___ns_name_skip, __ns_name_skip, GLIBC_PRIVATE);
66libc_hidden_ver (___ns_name_skip, __ns_name_skip)
67
68#if OTHER_SHLIB_COMPAT (libresolv, GLIBC_2_9, GLIBC_2_34)
69compat_symbol (libresolv, ___ns_name_skip, ns_name_skip, GLIBC_2_9);
70#endif
71