/* -*- c-basic-offset: 8 -*-
   rdesktop: A Remote Desktop Protocol client.
   ASN.1 utility functions header
   Copyright 2017 Alexander Zakharov <uglym8@gmail.com>

   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/>.
*/
#ifndef RDASN_H
#define RDASN_H

#include <gnutls/gnutls.h>
#include <libtasn1.h>
#include <stdint.h>

#include "utils.h"

#ifdef  __cplusplus
extern "C" {
#endif

#define OID_SHA_WITH_RSA_SIGNATURE "1.3.14.3.2.15"
#define OID_MD5_WITH_RSA_SIGNATURE "1.3.14.3.2.25"

/**
 * Initialize the ASN.1 library.
 *
 * This function initializes the ASN.1 library and should be called before any other ASN.1 functions.
 *
 * Returns: 0 on success, or a non-zero error code on failure.
 */
extern int init_asn1_lib(void);

/**
 * Encode an RSA public key into DER PKCS#1 format.
 *
 * This function encodes an RSA public key into DER PKCS#1 format. The modulus and exponent of the public key are
 * provided as input, and the encoded key is returned in the output buffer.
 *
 * Parameters:
 *   - m: A pointer to a gnutls_datum_t structure that contains the modulus of the public key.
 *   - e: A pointer to a gnutls_datum_t structure that contains the exponent of the public key.
 *   - out: A pointer to the output buffer where the encoded key will be stored.
 *   - out_len: A pointer to an integer that will be set to the length of the encoded key.
 *
 * Returns: 0 on success, or a non-zero error code on failure.
 */
extern int write_pkcs1_der_pubkey(const gnutls_datum_t *m, const gnutls_datum_t *e, uint8_t *out, int *out_len);

/**
 * Read the public key algorithm OID from a DER encoded x.509 certificate.
 *
 * This function reads the public key algorithm OID from a DER encoded x.509 certificate. The certificate is provided
 * as input, and the OID is returned in the output buffer.
 *
 * Parameters:
 *   - data: A pointer to the input buffer that contains the DER encoded x.509 certificate.
 *   - len: The length of the input buffer.
 *   - oid: A pointer to the output buffer where the OID will be stored.
 *   - oid_size: A pointer to an integer that will be set to the length of the OID.
 *
 * Returns: 0 on success, or a non-zero error code on failure.
 */
extern int libtasn_read_cert_pk_oid(uint8_t *data, size_t len, char *oid, size_t *oid_size);

/**
 * Read the public key parameters from a DER encoded x.509 certificate.
 *
 * This function reads the public key parameters (modulus and exponent) from a DER encoded x.509 certificate. The
 * certificate is provided as input, and the parameters are returned in the output buffers.
 *
 * Parameters:
 *   - data: A pointer to the input buffer that contains the DER encoded x.509 certificate.
 *   - len: The length of the input buffer.
 *   - m: A pointer to a gnutls_datum_t structure that will be set to the modulus of the public key.
 *   - e: A pointer to a gnutls_datum_t structure that will be set to the exponent of the public key.
 *
 * Returns: 0 on success, or a non-zero error code on failure.
 */
extern int libtasn_read_cert_pk_parameters(uint8_t *data, size_t len, gnutls_datum_t *m, gnutls_datum_t *e);

#ifdef __cplusplus
}
#endif

#endif /* RDASN_H */