[dnssec] implement nsec3 hashing

dnssec/Makefile.am

@@ -27,6 +27,8 @@ libdnssec_la_SOURCES =	\
 	src/keystore.h \
 	src/nsec/bitmap.c \
 	src/nsec/bitmap.h \
+	src/nsec/hash.c \
+	src/nsec/hash.h \
 	src/shared.h \
 	src/sign.c \
 	src/sign.h \

dnssec/src/error.h

@@ -36,6 +36,8 @@ enum dnssec_error {
 	DNSSEC_SIGN_INIT_ERROR,
 	DNSSEC_SIGN_ERROR,
 	DNSSEC_INVALID_SIGNATURE,
+	DNSSEC_INVALID_NSEC3_ALGORITHM,
+	DNSSEC_NSEC3_HASHING_ERROR,
 };
 
 static inline int dnssec_errno_to_error(int ecode)

dnssec/src/nsec/hash.c

+#include <assert.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/crypto.h>
+#include <string.h>
+
+#include "error.h"
+#include "nsec/hash.h"
+#include "shared.h"
+#include "wire.h"
+
+static void free_gnutls_hash(gnutls_hash_hd_t *ptr)
+{
+	if (*ptr) {
+		gnutls_hash_deinit(*ptr, NULL);
+	}
+}
+
+#define _cleanup_digest_ _cleanup_(free_gnutls_hash)
+
+/*!
+ * 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, unsigned 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_digest_ 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 ----------------------------------------------------------- */
+
+/*!
+ * Free NSEC3 parameters.
+ */
+void dnssec_nsec3_params_free(dnssec_nsec3_params_t *params)
+{
+	if (!params) {
+		return;
+	}
+
+	dnssec_binary_free(&params->salt);
+	clear_struct(&params);
+}
+
+/*!
+ * Parse NSEC3 parameters from NSEC3PARAM RDATA.
+ *
+ * \see RFC 5155 (section 4.2)
+ */
+int dnssec_nsec3_params_from_rdata(dnssec_nsec3_params_t *params,
+				   const dnssec_binary_t *rdata)
+{
+	if (!params || !rdata || !rdata->data) {
+		return DNSSEC_EINVAL;
+	}
+
+	dnssec_nsec3_params_t new_params = { 0 };
+
+	wire_ctx_t wire;
+	wire_init_binary(&wire, rdata);
+
+	if (wire_available(&wire) < 5) {
+		return DNSSEC_MALFORMED_DATA;
+	}
+
+	new_params.algorithm  = wire_read_u8(&wire);
+	new_params.flags      = wire_read_u8(&wire);
+	new_params.iterations = wire_read_u16(&wire);
+	new_params.salt.size  = wire_read_u8(&wire);
+
+	if (wire_available(&wire) != new_params.salt.size) {
+		return DNSSEC_MALFORMED_DATA;
+	}
+
+	new_params.salt.data = malloc(new_params.salt.size);
+	if (new_params.salt.data == NULL) {
+		return DNSSEC_ENOMEM;
+	}
+
+	wire_read_binary(&wire, &new_params.salt);
+	assert(wire_tell(&wire) == rdata->size);
+
+	*params = new_params;
+
+	return DNSSEC_EOK;
+}
+
+/*!
+ * Compute NSEC3 hash for given data.
+ */
+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.
+ */
+size_t dnssec_nsec3_hash_length(dnssec_nsec3_algorithm_t dnssec)
+{
+	gnutls_digest_algorithm_t gnutls = algorithm_d2g(dnssec);
+	if (gnutls == GNUTLS_DIG_UNKNOWN) {
+		return 0;
+	}
+
+	return gnutls_hash_get_len(gnutls);
+}

dnssec/src/nsec/hash.h

+#pragma once
+
+#include "binary.h"
+
+/*!
+ * DNSSEC NSEC3 algorithm numbers.
+ */
+typedef enum dnssec_nsec_algorithm {
+	DNSSEC_NSEC3_ALGORITHM_UNKNOWN = 0,
+	DNSSEC_NSEC3_ALGORITHM_SHA1 = 1,
+} dnssec_nsec3_algorithm_t;
+
+/*!
+ * DNSSEC NSEC3 parameters.
+ */
+typedef struct dnssec_nsec3_params {
+	dnssec_nsec3_algorithm_t algorithm;
+	uint8_t flags;
+	uint16_t iterations;
+	dnssec_binary_t salt;
+} dnssec_nsec3_params_t;
+
+/*!
+ * Free NSEC3 parameters.
+ */
+void dnssec_nsec3_params_free(dnssec_nsec3_params_t *params);
+
+/*!
+ * Parse NSEC3 parameters from NSEC3PARAM RDATA.
+ *
+ * \param params  Output parameters.
+ * \param rdata   NSEC3PARAM RDATA.
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int dnssec_nsec3_params_from_rdata(dnssec_nsec3_params_t *params,
+				   const dnssec_binary_t *rdata);
+
+/*!
+ * Compute NSEC3 hash for given data.
+ *
+ * \todo Input data must be converted to lowercase!
+ *
+ * \param[in]  data    Data to be hashed (usually domain name).
+ * \param[in]  params  NSEC3 parameters.
+ * \param[out] hash    Computed hash (will be allocated or resized).
+ *
+ * \return Error code, KNOT_EOK if successful.
+ */
+int dnssec_nsec3_hash(const dnssec_binary_t *data,
+		      const dnssec_nsec3_params_t *params,
+		      dnssec_binary_t *hash);
+
+/*!
+ * Get length of raw NSEC3 hash for a given algorithm.
+ *
+ * \param algorithm  NSEC3 algorithm number.
+ *
+ * \return Length of raw NSEC3 hash, zero on error.
+ */
+size_t dnssec_nsec3_hash_length(dnssec_nsec3_algorithm_t algorithm);

dnssec/tests/Makefile.am

@@ -12,6 +12,7 @@ check_PROGRAMS = \
 	key_keytag	\
 	key_pubkey	\
 	nsec_bitmap	\
+	nsec_hash	\
 	sign		\
 	sign_der	\
 	wire

dnssec/tests/nsec_hash.c

+#include <string.h>
+#include <tap/basic.h>
+
+#include "crypto.h"
+#include "error.h"
+#include "nsec/hash.h"
+
+void test_length(void)
+{
+	ok(dnssec_nsec3_hash_length(DNSSEC_NSEC3_ALGORITHM_SHA1) == 20,
+	   "dnssec_nsec3_hash_length() for SHA1");
+}
+
+void test_parsing(void)
+{
+	const dnssec_binary_t rdata = { .size = 9, .data = (uint8_t []) {
+		0x01,			// algorithm
+		0x00,			// flags
+		0x00, 0x0a,		// iterations
+		0x04,			// salt length
+		'a', 'b', 'c', 'd'	// salt
+	}};
+
+	dnssec_nsec3_params_t params = { 0 };
+	int result = dnssec_nsec3_params_from_rdata(&params, &rdata);
+	ok(result == DNSSEC_EOK, "dnssec_nsec3_params_from_rdata()");
+
+	ok(params.algorithm == 1, "algorithm");
+	ok(params.flags == 0, "flags");
+	ok(params.iterations == 10, "iterations");
+	ok(params.salt.size == 4, "salt length");
+	ok(params.salt.data != NULL && memcmp(params.salt.data, "abcd", 4) == 0,
+	   "salt content");
+
+	dnssec_nsec3_params_free(&params);
+	ok(params.salt.data == NULL, "dnssec_nsec3_params_free()");
+}
+
+void test_hashing(void)
+{
+	const dnssec_binary_t dname = {
+		.size = 13,
+		.data = (uint8_t *) "\x08""knot-dns""\x02""cz"
+	};
+
+	const dnssec_nsec3_params_t params = {
+		.algorithm = DNSSEC_NSEC3_ALGORITHM_SHA1,
+		.flags = 0,
+		.iterations = 7,
+		.salt = { .size = 14, .data = (uint8_t *) "happywithnsec3" }
+	};
+
+	const dnssec_binary_t expected = { .size = 20, .data = (uint8_t []) {
+		0x72, 0x40, 0x55, 0x83, 0x92, 0x93, 0x95, 0x28, 0xee, 0xa2,
+		0xcc, 0xe1, 0x13, 0xbe, 0xcd, 0x41, 0xee, 0x8a, 0x71, 0xfd
+	}};
+
+	dnssec_binary_t hash = { 0 };
+
+	int result = dnssec_nsec3_hash(&dname, &params, &hash);
+	ok(result == DNSSEC_EOK, "dnssec_nsec3_hash()");
+
+	ok(hash.size == expected.size && hash.data != NULL &&
+	   memcmp(hash.data, expected.data, expected.size) == 0,
+	   "valid hash");
+
+	dnssec_binary_free(&hash);
+}
+
+int main(void)
+{
+	plan_lazy();
+
+	dnssec_crypto_init();
+
+	test_length();
+	test_parsing();
+	test_hashing();
+
+	dnssec_crypto_cleanup();
+
+	return 0;
+}