/**
 * (C) 2007-18 - ntop.org and contributors
 *
 * 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 see <http://www.gnu.org/licenses/>
 *
 */

#if !defined(N2N_TRANSFORMS_H_)
#define N2N_TRANSFORMS_H_

#include <time.h>
#include "n2n_wire.h"

#define N2N_TRANSFORM_ID_USER_START     64
#define N2N_TRANSFORM_ID_MAX            65535

typedef enum n2n_transform {
  N2N_TRANSFORM_ID_INVAL = 0,
  N2N_TRANSFORM_ID_NULL = 1,
  N2N_TRANSFORM_ID_TWOFISH = 2,
  N2N_TRANSFORM_ID_AESCBC = 3,
  N2N_TRANSFORM_ID_CHACHA20 = 4,
} n2n_transform_t;

struct n2n_trans_op;

typedef int             (*n2n_transdeinit_f)( struct n2n_trans_op * arg );
typedef void            (*n2n_transtick_f)( struct n2n_trans_op * arg, time_t now );
typedef int             (*n2n_transform_f)( struct n2n_trans_op * arg,
                                            uint8_t * outbuf,
                                            size_t out_len,
                                            const uint8_t * inbuf,
                                            size_t in_len,
                                            const n2n_mac_t peer_mac);

/** Holds the info associated with a data transform plugin.
 *
 *  When a packet arrives the transform ID is extracted. This defines the code
 *  to use to decode the packet content. The transform code then decodes the
 *  packet and consults its internal key lookup.
 */
typedef struct n2n_trans_op {
  void *              priv;   /* opaque data. Key schedule goes here. */
  uint8_t             no_encryption; /* 1 if this transop does not perform encryption */
  n2n_transform_t     transform_id;
  size_t              tx_cnt;
  size_t              rx_cnt;

  n2n_transdeinit_f   deinit; /* destructor function */
  n2n_transtick_f    tick;   /* periodic maintenance */
  n2n_transform_f     fwd;    /* encode a payload */
  n2n_transform_f     rev;    /* decode a payload */
} n2n_trans_op_t;

#endif /* #if !defined(N2N_TRANSFORMS_H_) */