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/* Simple DNS record parser without textual name decoding.
Copyright (C) 2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <arpa/nameser.h>
#include <errno.h>
#include <stdbool.h>
#include <string.h>
bool
__ns_rr_cursor_next (struct ns_rr_cursor *c, struct ns_rr_wire *rr)
{
rr->rdata = NULL;
/* Extract the record owner name. */
int consumed = __ns_name_unpack (c->begin, c->end, c->current,
rr->rname, sizeof (rr->rname));
if (consumed < 0)
{
memset (rr, 0, sizeof (*rr));
__set_errno (EMSGSIZE);
return false;
}
c->current += consumed;
/* Extract the metadata. */
struct
{
uint16_t rtype;
uint16_t rclass;
uint32_t ttl;
uint16_t rdlength;
} __attribute__ ((packed)) metadata;
_Static_assert (sizeof (metadata) == 10, "sizeof metadata");
if (c->end - c->current < sizeof (metadata))
{
memset (rr, 0, sizeof (*rr));
__set_errno (EMSGSIZE);
return false;
}
memcpy (&metadata, c->current, sizeof (metadata));
c->current += sizeof (metadata);
/* Endianess conversion. */
rr->rtype = ntohs (metadata.rtype);
rr->rclass = ntohs (metadata.rclass);
rr->ttl = ntohl (metadata.ttl);
rr->rdlength = ntohs (metadata.rdlength);
/* Extract record data. */
if (c->end - c->current < rr->rdlength)
{
memset (rr, 0, sizeof (*rr));
__set_errno (EMSGSIZE);
return false;
}
rr->rdata = c->current;
c->current += rr->rdlength;
return true;
}
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