/*
 * utils_crypt - cipher utilities for cryptsetup
 *
 * Copyright (C) 2004-2007 Clemens Fruhwirth <clemens@endorphin.org>
 * Copyright (C) 2009-2021 Red Hat, Inc. All rights reserved.
 * Copyright (C) 2009-2021 Milan Broz
 *
 * 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <errno.h>

#include "libcryptsetup.h"
#include "utils_crypt.h"

int crypt_parse_name_and_mode(const char *s, char *cipher, int *key_nums,
			      char *cipher_mode)
{
	if (!s || !cipher || !cipher_mode)
		return -EINVAL;

	if (sscanf(s, "%" MAX_CIPHER_LEN_STR "[^-]-%" MAX_CIPHER_LEN_STR "s",
		   cipher, cipher_mode) == 2) {
		if (!strcmp(cipher_mode, "plain"))
			strcpy(cipher_mode, "cbc-plain");
		if (key_nums) {
			char *tmp = strchr(cipher, ':');
			*key_nums = tmp ? atoi(++tmp) : 1;
			if (!*key_nums)
				return -EINVAL;
		}

		return 0;
	}

	/* Short version for "empty" cipher */
	if (!strcmp(s, "null") || !strcmp(s, "cipher_null")) {
		strcpy(cipher, "cipher_null");
		strcpy(cipher_mode, "ecb");
		if (key_nums)
			*key_nums = 0;
		return 0;
	}

	if (sscanf(s, "%" MAX_CIPHER_LEN_STR "[^-]", cipher) == 1) {
		strcpy(cipher_mode, "cbc-plain");
		if (key_nums)
			*key_nums = 1;
		return 0;
	}

	return -EINVAL;
}

int crypt_parse_hash_integrity_mode(const char *s, char *integrity)
{
	char mode[MAX_CIPHER_LEN], hash[MAX_CIPHER_LEN];
	int r;

	if (!s || !integrity || strchr(s, '(') || strchr(s, ')'))
		return -EINVAL;

	r = sscanf(s, "%" MAX_CIPHER_LEN_STR "[^-]-%" MAX_CIPHER_LEN_STR "s", mode, hash);
	if (r == 2 && !isdigit(hash[0]))
		r = snprintf(integrity, MAX_CIPHER_LEN, "%s(%s)", mode, hash);
	else if (r == 2)
		r = snprintf(integrity, MAX_CIPHER_LEN, "%s-%s", mode, hash);
	else if (r == 1)
		r = snprintf(integrity, MAX_CIPHER_LEN, "%s", mode);
	else
		return -EINVAL;

	if (r < 0 || r >= MAX_CIPHER_LEN)
		return -EINVAL;

	return 0;
}

int crypt_parse_integrity_mode(const char *s, char *integrity,
			       int *integrity_key_size)
{
	int ks = 0, r = 0;

	if (!s || !integrity)
		return -EINVAL;

	// FIXME: do not hardcode it here

	/* AEAD modes */
	if (!strcmp(s, "aead") ||
	    !strcmp(s, "poly1305") ||
	    !strcmp(s, "none")) {
		strncpy(integrity, s, MAX_CIPHER_LEN);
		ks = 0;
	} else if (!strcmp(s, "hmac-sha1")) {
		strncpy(integrity, "hmac(sha1)", MAX_CIPHER_LEN);
		ks = 20;
	} else if (!strcmp(s, "hmac-sha256")) {
		strncpy(integrity, "hmac(sha256)", MAX_CIPHER_LEN);
		ks = 32;
	} else if (!strcmp(s, "hmac-sha512")) {
		ks = 64;
		strncpy(integrity, "hmac(sha512)", MAX_CIPHER_LEN);
	} else if (!strcmp(s, "cmac-aes")) {
		ks = 16;
		strncpy(integrity, "cmac(aes)", MAX_CIPHER_LEN);
	} else
		r = -EINVAL;

	if (integrity_key_size)
		*integrity_key_size = ks;

	return r;
}

int crypt_parse_pbkdf(const char *s, const char **pbkdf)
{
	const char *tmp = NULL;

	if (!s)
		return -EINVAL;

	if (!strcasecmp(s, CRYPT_KDF_PBKDF2))
		tmp = CRYPT_KDF_PBKDF2;
	else if (!strcasecmp(s, CRYPT_KDF_ARGON2I))
		tmp = CRYPT_KDF_ARGON2I;
	else if (!strcasecmp(s, CRYPT_KDF_ARGON2ID))
		tmp = CRYPT_KDF_ARGON2ID;

	if (!tmp)
		return -EINVAL;

	if (pbkdf)
		*pbkdf = tmp;

	return 0;
}

ssize_t crypt_hex_to_bytes(const char *hex, char **result, int safe_alloc)
{
	char buf[3] = "xx\0", *endp, *bytes;
	size_t i, len;

	len = strlen(hex);
	if (len % 2)
		return -EINVAL;
	len /= 2;

	bytes = safe_alloc ? crypt_safe_alloc(len) : malloc(len);
	if (!bytes)
		return -ENOMEM;

	for (i = 0; i < len; i++) {
		memcpy(buf, &hex[i * 2], 2);
		bytes[i] = strtoul(buf, &endp, 16);
		if (endp != &buf[2]) {
			safe_alloc ? crypt_safe_free(bytes) : free(bytes);
			return -EINVAL;
		}
	}
	*result = bytes;
	return i;
}

bool crypt_is_cipher_null(const char *cipher_spec)
{
	if (!cipher_spec)
		return false;
	return (strstr(cipher_spec, "cipher_null") || !strcmp(cipher_spec, "null"));
}