1/* Simple DNS record parser without textual name decoding.
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#include <string.h>
23
24bool
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 /* Endianness 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}
75