1 files changed, 142 insertions, 0 deletions
diff --git a/src/libdnssec/nsec/bitmap.c b/src/libdnssec/nsec/bitmap.c
new file mode 100644
index 0000000..001613a
--- /dev/null
+++ b/src/libdnssec/nsec/bitmap.c
@@ -0,0 +1,142 @@
+/*  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 <http://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;
+	}
+}