/* dtls -- a very basic DTLS implementation
 *
 * Copyright (C) 2011--2013 Olaf Bergmann <bergmann@tzi.org>
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
 * restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies
 * of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

/**
 * @file peer.h
 * @brief information about peers in a DTLS session
 */

#ifndef _DTLS_PEER_H_
#define _DTLS_PEER_H_

#include <sys/types.h>

#include "tinydtls.h"
#include "global.h"
#include "session.h"

#include "state.h"
#include "crypto.h"

typedef enum { DTLS_CLIENT=0, DTLS_SERVER } dtls_peer_type;

/** 
 * Holds security parameters, local state and the transport address
 * for each peer. */
typedef struct dtls_peer_t {
  struct dtls_peer_t *next;

  session_t session;	     /**< peer address and local interface */

  dtls_peer_type role;       /**< denotes if this host is DTLS_CLIENT or DTLS_SERVER */
  dtls_state_t state;        /**< DTLS engine state */

  dtls_security_parameters_t *security_params[2];
  dtls_handshake_parameters_t *handshake_params;
} dtls_peer_t;

static inline dtls_security_parameters_t *dtls_security_params_epoch(dtls_peer_t *peer, uint16_t epoch)
{
  if (peer->security_params[0] && peer->security_params[0]->epoch == epoch) {
    return peer->security_params[0];
  } else if (peer->security_params[1] && peer->security_params[1]->epoch == epoch) {
    return peer->security_params[1];
  } else {
    return NULL;
  }
}

static inline dtls_security_parameters_t *dtls_security_params(dtls_peer_t *peer)
{
  return peer->security_params[0];
}

static inline dtls_security_parameters_t *dtls_security_params_next(dtls_peer_t *peer)
{
  if (peer->security_params[1])
    dtls_security_free(peer->security_params[1]);

  peer->security_params[1] = dtls_security_new();
  if (!peer->security_params[1]) {
    return NULL;
  }
  peer->security_params[1]->epoch = peer->security_params[0]->epoch + 1;
  return peer->security_params[1];
}

static inline void dtls_security_params_free_other(dtls_peer_t *peer)
{
  dtls_security_parameters_t * security0 = peer->security_params[0];
  dtls_security_parameters_t * security1 = peer->security_params[1];

  if (!security0 || !security1 || security0->epoch < security1->epoch)
    return;

  dtls_security_free(security1);
  peer->security_params[1] = NULL;
}

static inline void dtls_security_params_switch(dtls_peer_t *peer)
{
  dtls_security_parameters_t * security = peer->security_params[1];

  peer->security_params[1] = peer->security_params[0];
  peer->security_params[0] = security;
}

void peer_init();

/**
 * Creates a new peer for given @p session. The current configuration
 * is initialized with the cipher suite TLS_NULL_WITH_NULL_NULL (i.e.
 * no security at all). This function returns a pointer to the new
 * peer or NULL on error. The caller is responsible for releasing the
 * storage allocated for this peer using dtls_free_peer().
 *
 * @param session  The remote peer's address and local interface index.
 * @return A pointer to a newly created and initialized peer object
 * or NULL on error.
 */
dtls_peer_t *dtls_new_peer(const session_t *session);

/** Releases the storage allocated to @p peer. */
void dtls_free_peer(dtls_peer_t *peer);

/** Returns the current state of @p peer. */
static inline dtls_state_t dtls_peer_state(const dtls_peer_t *peer) {
  return peer->state;
}

/**
 * Checks if given @p peer is connected. This function returns
 * @c 1 if connected, or @c 0 otherwise.
 */
static inline int dtls_peer_is_connected(const dtls_peer_t *peer) {
  return peer->state == DTLS_STATE_CONNECTED;
}

#endif /* _DTLS_PEER_H_ */