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