mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-21 20:40:05 +00:00
63 lines
1.8 KiB
C
63 lines
1.8 KiB
C
/* Initialize a simple DNS packet parser.
|
|
Copyright (C) 2022-2024 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_init (struct ns_rr_cursor *c,
|
|
const unsigned char *buf, size_t len)
|
|
{
|
|
c->begin = buf;
|
|
c->end = buf + len;
|
|
|
|
/* Check for header size and 16-bit question count value (it must be 1). */
|
|
if (len < 12 || buf[4] != 0 || buf[5] != 1)
|
|
{
|
|
__set_errno (EMSGSIZE);
|
|
c->current = c->end;
|
|
return false;
|
|
}
|
|
c->current = buf + 12;
|
|
|
|
int consumed = __ns_name_length_uncompressed (c->current, c->end);
|
|
if (consumed < 0)
|
|
{
|
|
__set_errno (EMSGSIZE);
|
|
c->current = c->end;
|
|
c->first_rr = NULL;
|
|
return false;
|
|
}
|
|
c->current += consumed;
|
|
|
|
/* Ensure there is room for question type and class. */
|
|
if (c->end - c->current < 4)
|
|
{
|
|
__set_errno (EMSGSIZE);
|
|
c->current = c->end;
|
|
c->first_rr = NULL;
|
|
return false;
|
|
}
|
|
c->current += 4;
|
|
c->first_rr = c->current;
|
|
|
|
return true;
|
|
}
|