1/* Skip over an uncompressed name in wire format.
2 Copyright (C) 2022-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19#include <arpa/nameser.h>
20#include <errno.h>
21#include <stdbool.h>
22
23int
24__ns_name_length_uncompressed (const unsigned char *p,
25 const unsigned char *eom)
26{
27 const unsigned char *start = p;
28
29 while (true)
30 {
31 if (p == eom)
32 {
33 /* Truncated packet: no room for label length. */
34 __set_errno (EMSGSIZE);
35 return -1;
36 }
37
38 unsigned char b = *p;
39 ++p;
40 if (b == 0)
41 {
42 /* Root label. */
43 size_t length = p - start;
44 if (length > NS_MAXCDNAME)
45 {
46 /* Domain name too long. */
47 __set_errno (EMSGSIZE);
48 return -1;
49 }
50 return length;
51 }
52
53 if (b <= 63)
54 {
55 /* Regular label. */
56 if (b <= eom - p)
57 p += b;
58 else
59 {
60 /* Truncated packet: label incomplete. */
61 __set_errno (EMSGSIZE);
62 return -1;
63 }
64 }
65 else
66 {
67 /* Compression reference or corrupted label length. */
68 __set_errno (EMSGSIZE);
69 return -1;
70 }
71 }
72}
73