/* Chrysalide - Outil d'analyse de fichiers binaires
 * keymgn.c - mise en place et gestion des clefs cryptographiques
 *
 * Copyright (C) 2016 Cyrille Bagard
 *
 *  This file is part of Chrysalide.
 *
 *  OpenIDA 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.
 *
 *  OpenIDA 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 Foobar.  If not, see <http://www.gnu.org/licenses/>.
 */


#include "keymgn.h"


#include <glib.h>
#include <malloc.h>
#include <stdio.h>
#include <unistd.h>
#include <openssl/evp.h>
#include <openssl/rsa.h>


#include <i18n.h>


#include "../../common/xdg.h"



/* Met en place de nouvelles clefs RSA. */
static bool generate_user_rsa_keys(const char *, const char *);



/******************************************************************************
*                                                                             *
*  Paramètres  : -                                                            *
*                                                                             *
*  Description : S'assure que l'utilisateur dispose de clefs RSA.             *
*                                                                             *
*  Retour      : Bilan de l'opération.                                        *
*                                                                             *
*  Remarques   : -                                                            *
*                                                                             *
******************************************************************************/

bool ensure_user_has_rsa_keys(void)
{
    bool result;                            /* Bilan à retourner           */
    char *priv;                             /* Chemin de la clef privée    */
    char *pub;                              /* Chemin de la clef publique  */
    int priv_check;                         /* Bilan d'une vérification #1 */
    int pub_check;                          /* Bilan d'une vérification #2 */

    result = NULL;

    priv = get_xdg_config_dir("chrysalide" G_DIR_SEPARATOR_S "id_rsa.priv");
    pub = get_xdg_config_dir("chrysalide" G_DIR_SEPARATOR_S "id_rsa.pub");

    priv_check = access(priv, R_OK);
    pub_check = access(pub, R_OK);

    result = (priv_check == 0 && pub_check == 0);

    if (!result)
    {
        result = generate_user_rsa_keys(priv, pub);

        if (!result)
            fprintf(stderr, _("Unable to create new user RSA key pair."));

    }

    free(priv);
    free(pub);

    return result;

}


/******************************************************************************
*                                                                             *
*  Paramètres  : priv = chemin d'accès pour la clef privée.                   *
*                pub  = chemin d'accès pour la clef publique.                 *
*                                                                             *
*  Description : Met en place de nouvelles clefs RSA.                         *
*                                                                             *
*  Retour      : Bilan de l'opération.                                        *
*                                                                             *
*  Remarques   : -                                                            *
*                                                                             *
******************************************************************************/

static bool generate_user_rsa_keys(const char *priv, const char *pub)
{
    bool result;                            /* Bilan à retourner           */
    EVP_PKEY_CTX *ctx;                      /* Contexte de génération      */
    int ret;                                /* Bilan d'un appel            */
    EVP_PKEY *pair;                         /* Paire de clefs RSA générée  */
    char *filename;                         /* Chemin d'accès              */
    FILE *stream;                           /* Flux ouvert en écriture     */

    result = false;

    /**
     * Cf. https://www.openssl.org/docs/manmaster/crypto/EVP_PKEY_keygen.html
     */

    ctx = EVP_PKEY_CTX_new_id(EVP_PKEY_RSA, NULL);
    if (ctx == NULL) goto euhrk_exit;

    ret = EVP_PKEY_keygen_init(ctx);
    if (ret != 1) goto euhrk_exit;

    ret = EVP_PKEY_CTX_set_rsa_keygen_bits(ctx, 2048);
    if (ret != 1) goto euhrk_exit;

    ret = EVP_PKEY_keygen(ctx, &pair);
    if (ret != 1) goto euhrk_exit;

    /* Clef privée */

    stream = fopen(priv, "wt");
    if (stream == NULL) goto euhrk_bad_write;

    ret = PEM_write_PrivateKey(stream, pair, NULL, NULL, 0, NULL, NULL);
    if (ret != 1) goto euhrk_bad_write;

    fclose(stream);

    /* Clef publique */

    stream = fopen(pub, "wt");
    if (stream == NULL) goto euhrk_bad_write;

    ret = PEM_write_PUBKEY(stream, pair);
    if (ret != 1) goto euhrk_bad_write;

    result = true;

 euhrk_bad_write:

    fclose(stream);

    EVP_PKEY_free(pair);

 euhrk_exit:

    EVP_PKEY_CTX_free(ctx);

    return result;

}