1 files changed, 165 insertions, 0 deletions
diff --git a/src/libdnssec/shared/dname.c b/src/libdnssec/shared/dname.c
new file mode 100644
index 0000000..61a5034
--- /dev/null
+++ b/src/libdnssec/shared/dname.c
@@ -0,0 +1,165 @@
+/*  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 <assert.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+
+#include "libdnssec/shared/dname.h"
+#include "libdnssec/shared/shared.h"
+#include "contrib/tolower.h"
+
+/*!
+ * Get length of a domain name in wire format.
+ */
+size_t dname_length(const uint8_t *dname)
+{
+	if (!dname) {
+		return 0;
+	}
+
+	const uint8_t *scan = dname;
+	uint8_t label_len;
+	do {
+		label_len = *scan;
+		scan += 1 + label_len;
+	} while (label_len > 0);
+	assert(scan > dname);
+
+	size_t length = scan - dname;
+	if (length > DNAME_MAX_LENGTH) {
+		return 0;
+	}
+
+	return length;
+}
+
+/*!
+ * Copy domain name in wire format.
+ */
+uint8_t *dname_copy(const uint8_t *dname)
+{
+	if (!dname) {
+		return NULL;
+	}
+
+	size_t length = dname_length(dname);
+	if (length == 0) {
+		return NULL;
+	}
+
+	uint8_t *copy = malloc(length);
+	if (!copy) {
+		return NULL;
+	}
+
+	memmove(copy, dname, length);
+	return copy;
+}
+
+/*!
+ * Normalize dname label in-place.
+ *
+ * \return Number of processed bytes, 0 if we encounter the last label.
+ */
+static uint8_t normalize_label(uint8_t *label)
+{
+	assert(label);
+
+	uint8_t len = *label;
+	if (len == 0 || len > DNAME_MAX_LABEL_LENGTH) {
+		return 0;
+	}
+
+	for (uint8_t *scan = label + 1, *end = scan + len; scan < end; scan++) {
+		*scan = knot_tolower(*scan);
+	}
+
+	return len + 1;
+}
+
+/*!
+ * Normalize domain name in wire format.
+ */
+void dname_normalize(uint8_t *dname)
+{
+	if (!dname) {
+		return;
+	}
+
+	uint8_t read, *scan = dname;
+	do {
+		read = normalize_label(scan);
+		scan += read;
+	} while (read > 0);
+}
+
+/*!
+ * Compare dname labels case insensitively.
+ */
+static int label_casecmp(const uint8_t *a, const uint8_t *b, uint8_t len)
+{
+	assert(a);
+	assert(b);
+
+	for (const uint8_t *a_end = a + len; a < a_end; a++, b++) {
+		if (knot_tolower(*a) != knot_tolower(*b)) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
+/*!
+ * Check if two dnames are equal.
+ */
+bool dname_equal(const uint8_t *one, const uint8_t *two)
+{
+	if (!one || !two) {
+		return false;
+	}
+
+	const uint8_t *scan_one = one;
+	const uint8_t *scan_two = two;
+
+	for (;;) {
+		if (*scan_one != *scan_two) {
+			return false;
+		}
+
+		uint8_t len = *scan_one;
+		if (len == 0) {
+			return true;
+		} else if (len > DNAME_MAX_LABEL_LENGTH) {
+			return false;
+		}
+
+		scan_one += 1;
+		scan_two += 1;
+
+		if (!label_casecmp(scan_one, scan_two, len)) {
+			return false;
+		}
+
+		scan_one += len;
+		scan_two += len;
+	}
+
+	return true;
+}