1 files changed, 78 insertions, 0 deletions
diff --git a/src/knot/zone/serial.c b/src/knot/zone/serial.c
new file mode 100644
index 0000000..0be5cbe
--- /dev/null
+++ b/src/knot/zone/serial.c
@@ -0,0 +1,78 @@
+/*  Copyright (C) 2019 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 <assert.h>
+#include <time.h>
+
+#include "knot/conf/conf.h"
+#include "knot/zone/serial.h"
+
+static const serial_cmp_result_t diffbrief2result[4] = {
+	[0] = SERIAL_EQUAL,
+	[1] = SERIAL_GREATER,
+	[2] = SERIAL_INCOMPARABLE,
+	[3] = SERIAL_LOWER,
+};
+
+serial_cmp_result_t serial_compare(uint32_t s1, uint32_t s2)
+{
+	uint64_t diff = ((uint64_t)s1 + ((uint64_t)1 << 32) - s2) & 0xffffffff;
+	int diffbrief = (diff >> 31 << 1) | ((diff & 0x7fffffff) ? 1 : 0);
+	assert(diffbrief > -1 && diffbrief < 4);
+	return diffbrief2result[diffbrief];
+}
+
+static uint32_t serial_dateserial(uint32_t current)
+{
+	struct tm now;
+	time_t current_time = time(NULL);
+	struct tm *gmtime_result = gmtime_r(&current_time, &now);
+	if (gmtime_result == NULL) {
+		return current;
+	}
+	return (1900 + now.tm_year) * 1000000 +
+	       (   1 + now.tm_mon ) *   10000 +
+	       (       now.tm_mday) *     100;
+}
+
+uint32_t serial_next(uint32_t current, int policy, uint32_t must_increment)
+{
+	uint32_t minimum;
+	switch (policy) {
+	case SERIAL_POLICY_INCREMENT:
+		minimum = current;
+		break;
+	case SERIAL_POLICY_UNIXTIME:
+		minimum = time(NULL);
+		break;
+	case SERIAL_POLICY_DATESERIAL:
+		minimum = serial_dateserial(current);
+		break;
+	default:
+		assert(0);
+		return 0;
+	}
+	if (serial_compare(minimum, current) != SERIAL_GREATER) {
+		return current + must_increment;
+	} else {
+		return minimum;
+	}
+}
+
+serial_cmp_result_t kserial_cmp(kserial_t a, kserial_t b)
+{
+	return ((a.valid && b.valid) ? serial_compare(a.serial, b.serial) : SERIAL_INCOMPARABLE);
+}