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/* Copyright (C) 2018 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <limits.h>
#include <stdint.h>
#include <string.h>
#include "libdnssec/nsec.h"
#include "libdnssec/shared/shared.h"
#define BITMAP_WINDOW_SIZE 256
#define BITMAP_WINDOW_BYTES (BITMAP_WINDOW_SIZE/CHAR_BIT)
#define BITMAP_WINDOW_COUNT 256
/*!
* One window of an NSEC bitmap.
*/
typedef struct window {
uint8_t used;
uint8_t data[BITMAP_WINDOW_BYTES];
} window_t;
struct dnssec_nsec_bitmap {
int used;
window_t windows[BITMAP_WINDOW_COUNT];
};
/* -- public API ----------------------------------------------------------- */
/*!
* Allocate new bit map encoding context.
*/
_public_
dnssec_nsec_bitmap_t *dnssec_nsec_bitmap_new(void)
{
dnssec_nsec_bitmap_t *bitmap = malloc(sizeof(*bitmap));
if (!bitmap) {
return NULL;
}
dnssec_nsec_bitmap_clear(bitmap);
return bitmap;
}
/*!
* Clear existing bit map encoding context.
*/
_public_
void dnssec_nsec_bitmap_clear(dnssec_nsec_bitmap_t *bitmap)
{
clear_struct(bitmap);
}
/*!
* Free bit map encoding context.
*/
_public_
void dnssec_nsec_bitmap_free(dnssec_nsec_bitmap_t *bitmap)
{
free(bitmap);
}
/*!
* Add one RR type into the bitmap.
*/
_public_
void dnssec_nsec_bitmap_add(dnssec_nsec_bitmap_t *bitmap, uint16_t type)
{
int win = type / BITMAP_WINDOW_SIZE;
int bit = type % BITMAP_WINDOW_SIZE;
if (bitmap->used <= win) {
bitmap->used = win + 1;
}
int win_byte = bit / CHAR_BIT;
int win_bit = bit % CHAR_BIT;
window_t *window = &bitmap->windows[win];
window->data[win_byte] |= 0x80 >> win_bit;
if (window->used <= win_byte) {
window->used = win_byte + 1;
}
}
/*!
* Compute the size of the encoded bitmap.
*/
_public_
size_t dnssec_nsec_bitmap_size(const dnssec_nsec_bitmap_t *bitmap)
{
size_t result = 0;
for (int i = 0; i < bitmap->used; i++) {
int used = bitmap->windows[i].used;
if (used == 0) {
continue;
}
result += 2 + used; // windows number, window size, data
}
return result;
}
/*!
* Write encoded bitmap into the given buffer.
*/
_public_
void dnssec_nsec_bitmap_write(const dnssec_nsec_bitmap_t *bitmap, uint8_t *output)
{
uint8_t *write_ptr = output;
for (int win = 0; win < bitmap->used; win++) {
int used = bitmap->windows[win].used;
if (used == 0) {
continue;
}
*write_ptr = (uint8_t)win;
write_ptr += 1;
*write_ptr = (uint8_t)used;
write_ptr += 1;
memmove(write_ptr, bitmap->windows[win].data, used);
write_ptr += used;
}
}
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