1 files changed, 125 insertions, 0 deletions
diff --git a/src/libdnssec/nsec/hash.c b/src/libdnssec/nsec/hash.c
new file mode 100644
index 0000000..897320f
--- /dev/null
+++ b/src/libdnssec/nsec/hash.c
@@ -0,0 +1,125 @@
+/*  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 <assert.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+#include <string.h>
+
+#include "libdnssec/error.h"
+#include "libdnssec/nsec.h"
+#include "libdnssec/shared/shared.h"
+
+/*!
+ * Compute NSEC3 hash for given data and algorithm.
+ *
+ * \see RFC 5155
+ *
+ * \todo Input data should be converted to lowercase.
+ */
+static int nsec3_hash(gnutls_digest_algorithm_t algorithm, int iterations,
+		      const dnssec_binary_t *salt, const dnssec_binary_t *data,
+		      dnssec_binary_t *hash)
+{
+	assert(salt);
+	assert(data);
+	assert(hash);
+
+	int hash_size = gnutls_hash_get_len(algorithm);
+	if (hash_size <= 0) {
+		return DNSSEC_NSEC3_HASHING_ERROR;
+	}
+
+	int result = dnssec_binary_resize(hash, hash_size);
+	if (result != DNSSEC_EOK) {
+		return result;
+	}
+
+	_cleanup_hash_ gnutls_hash_hd_t digest = NULL;
+	result = gnutls_hash_init(&digest, algorithm);
+	if (result < 0) {
+		return DNSSEC_NSEC3_HASHING_ERROR;
+	}
+
+	const uint8_t *in = data->data;
+	size_t in_size = data->size;
+
+	for (int i = 0; i <= iterations; i++) {
+		result = gnutls_hash(digest, in, in_size);
+		if (result < 0) {
+			return DNSSEC_NSEC3_HASHING_ERROR;
+		}
+
+		result = gnutls_hash(digest, salt->data, salt->size);
+		if (result < 0) {
+			return DNSSEC_NSEC3_HASHING_ERROR;
+		}
+
+		gnutls_hash_output(digest, hash->data);
+
+		in = hash->data;
+		in_size = hash->size;
+	}
+
+	return DNSSEC_EOK;
+}
+
+/*!
+ * Get GnuTLS digest algorithm from DNSSEC algorithm number.
+ */
+static gnutls_digest_algorithm_t algorithm_d2g(dnssec_nsec3_algorithm_t dnssec)
+{
+	switch (dnssec) {
+	case DNSSEC_NSEC3_ALGORITHM_SHA1: return GNUTLS_DIG_SHA1;
+	default:                          return GNUTLS_DIG_UNKNOWN;
+	}
+}
+
+/* -- public API ----------------------------------------------------------- */
+
+/*!
+ * Compute NSEC3 hash for given data.
+ */
+_public_
+int dnssec_nsec3_hash(const dnssec_binary_t *data,
+		      const dnssec_nsec3_params_t *params,
+		      dnssec_binary_t *hash)
+{
+	if (!data || !params || !hash) {
+		return DNSSEC_EINVAL;
+	}
+
+	gnutls_digest_algorithm_t algorithm = algorithm_d2g(params->algorithm);
+	if (algorithm == GNUTLS_DIG_UNKNOWN) {
+		return DNSSEC_INVALID_NSEC3_ALGORITHM;
+	}
+
+	return nsec3_hash(algorithm, params->iterations, &params->salt, data, hash);
+}
+
+/*!
+ * Get length of raw NSEC3 hash for a given algorithm.
+ */
+_public_
+size_t dnssec_nsec3_hash_length(dnssec_nsec3_algorithm_t algorithm)
+{
+	gnutls_digest_algorithm_t gnutls = algorithm_d2g(algorithm);
+	if (gnutls == GNUTLS_DIG_UNKNOWN) {
+		return 0;
+	}
+
+	return gnutls_hash_get_len(gnutls);
+}