/* net_crypto.h
* 
* Functions for the core network crypto.
*
 
    Copyright (C) 2013 Tox project All Rights Reserved.

    This file is part of Tox.

    Tox 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.

    Tox 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 Tox.  If not, see <http://www.gnu.org/licenses/>.
    
*/
#ifndef NET_CRYPTO_H 
#define NET_CRYPTO_H  

#include "Lossless_UDP.h"

#ifdef __cplusplus
extern "C" {
#endif

/* Our public key. */
extern uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];
extern uint8_t self_secret_key[crypto_box_SECRETKEYBYTES];

#define ENCRYPTION_PADDING (crypto_box_ZEROBYTES - crypto_box_BOXZEROBYTES)

/* encrypts plain of length length to encrypted of length + 16 using the 
   public key(32 bytes) of the receiver and the secret key of the sender and a 24 byte nonce
   return -1 if there was a problem.
   return length of encrypted data if everything was fine. */
int encrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce, 
                                       uint8_t * plain, uint32_t length, uint8_t * encrypted);


/* decrypts encrypted of length length to plain of length length - 16 using the
   public key(32 bytes) of the sender, the secret key of the receiver and a 24 byte nonce
   return -1 if there was a problem(decryption failed)
   return length of plain data if everything was fine. */
int decrypt_data(uint8_t * public_key, uint8_t * secret_key, uint8_t * nonce, 
                                       uint8_t * encrypted, uint32_t length, uint8_t * plain);


/* fill the given nonce with random bytes. */
void random_nonce(uint8_t * nonce);


/* return 0 if there is no received data in the buffer 
   return -1  if the packet was discarded.
   return length of received data if successful */
int read_cryptpacket(int crypt_connection_id, uint8_t * data);


/* return 0 if data could not be put in packet queue
   return 1 if data was put into the queue */
int write_cryptpacket(int crypt_connection_id, uint8_t * data, uint32_t length);

/* create a request to peer with public_key.
   packet must be an array of MAX_DATA_SIZE big.
   Data represents the data we send with the request with length being the length of the data.
   request_id is the id of the request (32 = friend request, 254 = ping request)
   returns -1 on failure
   returns the length of the created packet on success */
int create_request(uint8_t * packet, uint8_t * public_key, uint8_t * data, uint32_t length, uint8_t request_id);


/* puts the senders public key in the request in public_key, the data from the request 
   in data if a friend or ping request was sent to us and returns the length of the data.
   packet is the request packet and length is its length
   return -1 if not valid request. */
int handle_request(uint8_t * public_key, uint8_t * data, uint8_t * packet, uint16_t length);


/* Start a secure connection with other peer who has public_key and ip_port
   returns -1 if failure
   returns crypt_connection_id of the initialized connection if everything went well. */
int crypto_connect(uint8_t * public_key, IP_Port ip_port);


/* kill a crypto connection
   return 0 if killed successfully
   return 1 if there was a problem. */
int crypto_kill(int crypt_connection_id);

/* handle an incoming connection
   return -1 if no crypto inbound connection
   return incoming connection id (Lossless_UDP one) if there is an incoming crypto connection
   Put the public key of the peer in public_key, the secret_nonce from the handshake into secret_nonce
   and the session public key for the connection in session_key
   to accept it see: accept_crypto_inbound(...)
   to refuse it just call kill_connection(...) on the connection id */
int crypto_inbound(uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key);


/* accept an incoming connection using the parameters provided by crypto_inbound
   return -1 if not successful
   returns the crypt_connection_id if successful */
int accept_crypto_inbound(int connection_id, uint8_t * public_key, uint8_t * secret_nonce, uint8_t * session_key);

/* return 0 if no connection, 1 we have sent a handshake, 2 if connexion is not confirmed yet 
   (we have received a handshake but no empty data packet), 3 if the connection is established.
   4 if the connection is timed out and waiting to be killed */
int is_cryptoconnected(int crypt_connection_id);


/* Generate our public and private keys
   Only call this function the first time the program starts. */
void new_keys();

/* save the public and private keys to the keys array
   Length must be crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES */
void save_keys(uint8_t * keys);

/* load the public and private keys from the keys array
   Length must be crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES */
void load_keys(uint8_t * keys);

/* run this to (re)initialize net_crypto
   sets all the global connection variables to their default values. */
void initNetCrypto();

/* main loop */
void doNetCrypto();

#ifdef __cplusplus
}
#endif

#endif