/**
 * (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 "n2n_keyfile.h"
#include "n2n_wire.h"


#define N2N_TRANSFORM_ID_INVAL          0       /* marks uninitialised data */
#define N2N_TRANSFORM_ID_NULL           1
#define N2N_TRANSFORM_ID_TWOFISH        2
#define N2N_TRANSFORM_ID_AESCBC         3
#define N2N_TRANSFORM_ID_LZO            4
#define N2N_TRANSFORM_ID_TWOFISH_LZO    5
#define N2N_TRANSFORM_ID_AESCBC_LZO     6
#define N2N_TRANSFORM_ID_USER_START     64
#define N2N_TRANSFORM_ID_MAX            65535


struct n2n_trans_op;
typedef struct n2n_trans_op n2n_trans_op_t;

struct n2n_tostat {
  uint8_t             can_tx;         /* Does this transop have a valid SA for encoding. */
  n2n_cipherspec_t    tx_spec;        /* If can_tx, the spec used to encode. */
};

typedef struct n2n_tostat n2n_tostat_t;


typedef int             (*n2n_transdeinit_f)( n2n_trans_op_t * arg );
typedef int             (*n2n_transaddspec_f)( n2n_trans_op_t * arg, 
                                               const n2n_cipherspec_t * cspec );
typedef n2n_tostat_t    (*n2n_transtick_f)( n2n_trans_op_t * arg, 
                                            time_t now );

typedef int             (*n2n_transform_f)( n2n_trans_op_t * arg,
                                            uint8_t * outbuf,
                                            size_t out_len,
                                            const uint8_t * inbuf,
                                            size_t in_len );

/** 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.
 */
struct n2n_trans_op {
  void *              priv;   /* opaque data. Key schedule goes here. */

  n2n_transform_t     transform_id;   /* link header enum to a transform */
  size_t              tx_cnt;
  size_t              rx_cnt;

  n2n_transdeinit_f   deinit; /* destructor function */
  n2n_transaddspec_f  addspec; /* parse opaque data from a key schedule file. */
  n2n_transtick_f     tick;   /* periodic maintenance */
  n2n_transform_f     fwd;    /* encode a payload */
  n2n_transform_f     rev;    /* decode a payload */
};

/* Setup a single twofish SA for single-key operation. */
int transop_twofish_setup( n2n_trans_op_t * ttt, 
                           n2n_sa_t sa_num,
                           uint8_t * encrypt_pwd, 
                           uint32_t encrypt_pwd_len );

/* Initialise an empty transop ready to receive cipherspec elements. */
int  transop_twofish_init( n2n_trans_op_t * ttt );
int  transop_aes_init( n2n_trans_op_t * ttt );
void transop_null_init( n2n_trans_op_t * ttt );

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