/*
 * Nettle crypto backend implementation
 *
 * Copyright (C) 2011-2016 Red Hat, Inc. All rights reserved.
 * Copyright (C) 2011-2016, Milan Broz
 *
 * This file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This file 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this file; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <nettle/sha.h>
#include <nettle/hmac.h>
#include <nettle/pbkdf2.h>
#include "crypto_backend.h"

static char *version = "Nettle";

typedef void (*init_func) (void *);
typedef void (*update_func) (void *, size_t, const uint8_t *);
typedef void (*digest_func) (void *, size_t, uint8_t *);
typedef void (*set_key_func) (void *, size_t, const uint8_t *);

struct hash_alg {
	const char *name;
	int length;
	init_func init;
	update_func update;
	digest_func digest;
	update_func hmac_update;
	digest_func hmac_digest;
	set_key_func hmac_set_key;
};

static struct hash_alg hash_algs[] = {
	{ "sha1", SHA1_DIGEST_SIZE,
		(init_func) sha1_init,
		(update_func) sha1_update,
		(digest_func) sha1_digest,
		(update_func) hmac_sha1_update,
		(digest_func) hmac_sha1_digest,
		(set_key_func) hmac_sha1_set_key,
	},
	{ "sha224", SHA224_DIGEST_SIZE,
		(init_func) sha224_init,
		(update_func) sha224_update,
		(digest_func) sha224_digest,
		(update_func) hmac_sha224_update,
		(digest_func) hmac_sha224_digest,
		(set_key_func) hmac_sha224_set_key,
	},
	{ "sha256", SHA256_DIGEST_SIZE,
		(init_func) sha256_init,
		(update_func) sha256_update,
		(digest_func) sha256_digest,
		(update_func) hmac_sha256_update,
		(digest_func) hmac_sha256_digest,
		(set_key_func) hmac_sha256_set_key,
	},
	{ "sha384", SHA384_DIGEST_SIZE,
		(init_func) sha384_init,
		(update_func) sha384_update,
		(digest_func) sha384_digest,
		(update_func) hmac_sha384_update,
		(digest_func) hmac_sha384_digest,
		(set_key_func) hmac_sha384_set_key,
	},
	{ "sha512", SHA512_DIGEST_SIZE,
		(init_func) sha512_init,
		(update_func) sha512_update,
		(digest_func) sha512_digest,
		(update_func) hmac_sha512_update,
		(digest_func) hmac_sha512_digest,
		(set_key_func) hmac_sha512_set_key,
	},
	{ "ripemd160", RIPEMD160_DIGEST_SIZE,
		(init_func) ripemd160_init,
		(update_func) ripemd160_update,
		(digest_func) ripemd160_digest,
		(update_func) hmac_ripemd160_update,
		(digest_func) hmac_ripemd160_digest,
		(set_key_func) hmac_ripemd160_set_key,
	},
	{ NULL, 0, NULL, NULL, NULL, NULL, NULL, NULL, }
};

struct crypt_hash {
	const struct hash_alg *hash;
	union {
		struct sha1_ctx sha1;
		struct sha224_ctx sha224;
		struct sha256_ctx sha256;
		struct sha384_ctx sha384;
		struct sha512_ctx sha512;
	} nettle_ctx;
};

struct crypt_hmac {
	const struct hash_alg *hash;
	union {
		struct hmac_sha1_ctx sha1;
		struct hmac_sha224_ctx sha224;
		struct hmac_sha256_ctx sha256;
		struct hmac_sha384_ctx sha384;
		struct hmac_sha512_ctx sha512;
	} nettle_ctx;
	size_t key_length;
	uint8_t *key;
};

uint32_t crypt_backend_flags(void)
{
	return 0;
}

static struct hash_alg *_get_alg(const char *name)
{
	int i = 0;

	while (name && hash_algs[i].name) {
		if (!strcmp(name, hash_algs[i].name))
			return &hash_algs[i];
		i++;
	}
	return NULL;
}

int crypt_backend_init(struct crypt_device *ctx)
{
	return 0;
}

const char *crypt_backend_version(void)
{
	return version;
}

/* HASH */
int crypt_hash_size(const char *name)
{
	struct hash_alg *ha = _get_alg(name);

	return ha ? ha->length : -EINVAL;
}

int crypt_hash_init(struct crypt_hash **ctx, const char *name)
{
	struct crypt_hash *h;

	h = malloc(sizeof(*h));
	if (!h)
		return -ENOMEM;

	h->hash = _get_alg(name);
	if (!h->hash) {
		free(h);
		return -EINVAL;
	}

	h->hash->init(&h->nettle_ctx);

	*ctx = h;
	return 0;
}

static void crypt_hash_restart(struct crypt_hash *ctx)
{
	ctx->hash->init(&ctx->nettle_ctx);
}

int crypt_hash_write(struct crypt_hash *ctx, const char *buffer, size_t length)
{
	ctx->hash->update(&ctx->nettle_ctx, length, (const uint8_t*)buffer);
	return 0;
}

int crypt_hash_final(struct crypt_hash *ctx, char *buffer, size_t length)
{
	if (length > (size_t)ctx->hash->length)
		return -EINVAL;

	ctx->hash->digest(&ctx->nettle_ctx, length, (uint8_t *)buffer);
	crypt_hash_restart(ctx);
	return 0;
}

int crypt_hash_destroy(struct crypt_hash *ctx)
{
	memset(ctx, 0, sizeof(*ctx));
	free(ctx);
	return 0;
}

/* HMAC */
int crypt_hmac_size(const char *name)
{
	return crypt_hash_size(name);
}

int crypt_hmac_init(struct crypt_hmac **ctx, const char *name,
		    const void *buffer, size_t length)
{
	struct crypt_hmac *h;

	h = malloc(sizeof(*h));
	if (!h)
		return -ENOMEM;
	memset(ctx, 0, sizeof(*ctx));


	h->hash = _get_alg(name);
	if (!h->hash)
		goto bad;

	h->key = malloc(length);
	if (!h->key)
		goto bad;

	memcpy(h->key, buffer, length);
	h->key_length = length;

	h->hash->init(&h->nettle_ctx);
	h->hash->hmac_set_key(&h->nettle_ctx, h->key_length, h->key);

	*ctx = h;
	return 0;
bad:
	free(h);
	return -EINVAL;
}

static void crypt_hmac_restart(struct crypt_hmac *ctx)
{
	ctx->hash->hmac_set_key(&ctx->nettle_ctx, ctx->key_length, ctx->key);
}

int crypt_hmac_write(struct crypt_hmac *ctx, const char *buffer, size_t length)
{
	ctx->hash->hmac_update(&ctx->nettle_ctx, length, (const uint8_t *)buffer);
	return 0;
}

int crypt_hmac_final(struct crypt_hmac *ctx, char *buffer, size_t length)
{
	if (length > (size_t)ctx->hash->length)
		return -EINVAL;

	ctx->hash->hmac_digest(&ctx->nettle_ctx, length, (uint8_t *)buffer);
	crypt_hmac_restart(ctx);
	return 0;
}

int crypt_hmac_destroy(struct crypt_hmac *ctx)
{
	memset(ctx->key, 0, ctx->key_length);
	free(ctx->key);
	memset(ctx, 0, sizeof(*ctx));
	free(ctx);
	return 0;
}

/* RNG - N/A */
int crypt_backend_rng(char *buffer, size_t length, int quality, int fips)
{
	return -EINVAL;
}

/* PBKDF */
int crypt_pbkdf(const char *kdf, const char *hash,
		const char *password, size_t password_length,
		const char *salt, size_t salt_length,
		char *key, size_t key_length,
		unsigned int iterations)
{
	struct crypt_hmac *h;
	int r;

	if (!kdf || strncmp(kdf, "pbkdf2", 6))
		return -EINVAL;

	r = crypt_hmac_init(&h, hash, password, password_length);
	if (r < 0)
		return r;

	nettle_pbkdf2(&h->nettle_ctx, h->hash->nettle_hmac_update,
		      h->hash->nettle_hmac_digest, h->hash->length, iterations,
		      salt_length, (const uint8_t *)salt, key_length,
		      (uint8_t *)key);
	crypt_hmac_destroy(h);

	return 0;
}
