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857c890d | 1 | /* Simple DNS record parser without textual name decoding. |
6d7e8eda | 2 | Copyright (C) 2022-2023 Free Software Foundation, Inc. |
857c890d FW |
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 | #include <string.h> | |
23 | ||
24 | bool | |
25 | __ns_rr_cursor_next (struct ns_rr_cursor *c, struct ns_rr_wire *rr) | |
26 | { | |
27 | rr->rdata = NULL; | |
28 | ||
29 | /* Extract the record owner name. */ | |
30 | int consumed = __ns_name_unpack (c->begin, c->end, c->current, | |
31 | rr->rname, sizeof (rr->rname)); | |
32 | if (consumed < 0) | |
33 | { | |
34 | memset (rr, 0, sizeof (*rr)); | |
35 | __set_errno (EMSGSIZE); | |
36 | return false; | |
37 | } | |
38 | c->current += consumed; | |
39 | ||
40 | /* Extract the metadata. */ | |
41 | struct | |
42 | { | |
43 | uint16_t rtype; | |
44 | uint16_t rclass; | |
45 | uint32_t ttl; | |
46 | uint16_t rdlength; | |
47 | } __attribute__ ((packed)) metadata; | |
48 | _Static_assert (sizeof (metadata) == 10, "sizeof metadata"); | |
49 | if (c->end - c->current < sizeof (metadata)) | |
50 | { | |
51 | memset (rr, 0, sizeof (*rr)); | |
52 | __set_errno (EMSGSIZE); | |
53 | return false; | |
54 | } | |
55 | memcpy (&metadata, c->current, sizeof (metadata)); | |
56 | c->current += sizeof (metadata); | |
57 | /* Endianess conversion. */ | |
58 | rr->rtype = ntohs (metadata.rtype); | |
59 | rr->rclass = ntohs (metadata.rclass); | |
60 | rr->ttl = ntohl (metadata.ttl); | |
61 | rr->rdlength = ntohs (metadata.rdlength); | |
62 | ||
63 | /* Extract record data. */ | |
64 | if (c->end - c->current < rr->rdlength) | |
65 | { | |
66 | memset (rr, 0, sizeof (*rr)); | |
67 | __set_errno (EMSGSIZE); | |
68 | return false; | |
69 | } | |
70 | rr->rdata = c->current; | |
71 | c->current += rr->rdlength; | |
72 | ||
73 | return true; | |
74 | } |