/* 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 "DHT.h"
#include "TCP_client.h"
#include <pthread.h>

#define CRYPTO_CONN_NO_CONNECTION 0
#define CRYPTO_CONN_COOKIE_REQUESTING 1 //send cookie request packets
#define CRYPTO_CONN_HANDSHAKE_SENT 2 //send handshake packets
#define CRYPTO_CONN_NOT_CONFIRMED 3 //send handshake packets
#define CRYPTO_CONN_ESTABLISHED 4
#define CRYPTO_CONN_TIMED_OUT 5

#define CRYPTO_PACKET_BUFFER_SIZE 16384 /* Must be a power of 2 */

/* Minimum packet rate per second. */
#define CRYPTO_PACKET_MIN_RATE 16.0

/* Minimum packet queue max length. */
#define CRYPTO_MIN_QUEUE_LENGTH 16

#define MAX_CRYPTO_PACKET_SIZE 1400

#define CRYPTO_DATA_PACKET_MIN_SIZE (1 + sizeof(uint16_t) + (sizeof(uint32_t) + sizeof(uint32_t)) + crypto_box_MACBYTES)

/* Max size of data in packets TODO*/
#define MAX_CRYPTO_DATA_SIZE (MAX_CRYPTO_PACKET_SIZE - CRYPTO_DATA_PACKET_MIN_SIZE)

/* Interval in ms between sending cookie request/handshake packets. */
#define CRYPTO_SEND_PACKET_INTERVAL 500
/* The maximum number of times we try to send the cookie request and handshake
   before giving up. */
#define MAX_NUM_SENDPACKET_TRIES 8

/* The timeout of no recieved UDP packets before the direct UDP connection is considered dead. */
#define UDP_DIRECT_TIMEOUT (MAX_NUM_SENDPACKET_TRIES * CRYPTO_SEND_PACKET_INTERVAL * 2)

#define PACKET_ID_PADDING 0
#define PACKET_ID_REQUEST 1
#define PACKET_ID_KILL    2

#define CRYPTO_RESERVED_PACKETS 16

#define MAX_TCP_CONNECTIONS 32
#define MAX_TCP_RELAYS_PEER 4

#define STATUS_TCP_NULL      0
#define STATUS_TCP_OFFLINE   1
#define STATUS_TCP_INVISIBLE 2 /* we know the other peer is connected to this relay but he isn't appearing online */
#define STATUS_TCP_ONLINE    3

/* All packets starting with a byte in this range are considered lossy packets. */
#define PACKET_ID_LOSSY_RANGE_START 192
#define PACKET_ID_LOSSY_RANGE_SIZE 63

#define CRYPTO_MAX_PADDING 8 /* All packets will be padded a number of bytes based on this number. */

typedef struct {
    uint64_t time;
    uint16_t length;
    uint8_t data[MAX_CRYPTO_DATA_SIZE];
} Packet_Data;

typedef struct {
    Packet_Data *buffer[CRYPTO_PACKET_BUFFER_SIZE];
    uint32_t  buffer_start;
    uint32_t  buffer_end; /* packet numbers in array: {buffer_start, buffer_end) */
} Packets_Array;

typedef struct {
    uint8_t public_key[crypto_box_PUBLICKEYBYTES]; /* The real public key of the peer. */
    uint8_t recv_nonce[crypto_box_NONCEBYTES]; /* Nonce of received packets. */
    uint8_t sent_nonce[crypto_box_NONCEBYTES]; /* Nonce of sent packets. */
    uint8_t sessionpublic_key[crypto_box_PUBLICKEYBYTES]; /* Our public key for this session. */
    uint8_t sessionsecret_key[crypto_box_SECRETKEYBYTES]; /* Our private key for this session. */
    uint8_t peersessionpublic_key[crypto_box_PUBLICKEYBYTES]; /* The public key of the peer. */
    uint8_t shared_key[crypto_box_BEFORENMBYTES]; /* The precomputed shared key from encrypt_precompute. */
    uint8_t status; /* 0 if no connection, 1 we are sending cookie request packets,
                     * 2 if we are sending handshake packets
                     * 3 if connection is not confirmed yet (we have received a handshake but no data packets yet),
                     * 4 if the connection is established.
                     * 5 if the connection is timed out.
                     */
    uint64_t cookie_request_number; /* number used in the cookie request packets for this connection */
    uint8_t dht_public_key[crypto_box_PUBLICKEYBYTES]; /* The dht public key of the peer */
    uint8_t dht_public_key_set; /* True if the dht public key is set, false if it isn't. */
    uint64_t dht_public_key_timestamp; /* Timestamp of the last time we confirmed the key was correct. */

    uint8_t *temp_packet; /* Where the cookie request/handshake packet is stored while it is being sent. */
    uint16_t temp_packet_length;
    uint64_t temp_packet_sent_time; /* The time at which the last temp_packet was sent in ms. */
    uint32_t temp_packet_num_sent;

    IP_Port ip_port; /* The ip and port to contact this guy directly.*/
    uint64_t direct_lastrecv_time; /* The Time at which we last received a direct packet in ms. */

    Packets_Array send_array;
    Packets_Array recv_array;

    int (*connection_status_callback)(void *object, int id, uint8_t status);
    void *connection_status_callback_object;
    int connection_status_callback_id;

    int (*connection_data_callback)(void *object, int id, uint8_t *data, uint16_t length);
    void *connection_data_callback_object;
    int connection_data_callback_id;

    int (*connection_lossy_data_callback)(void *object, int id, const uint8_t *data, uint16_t length);
    void *connection_lossy_data_callback_object;
    int connection_lossy_data_callback_id;

    uint64_t last_request_packet_sent;

    uint32_t packet_counter;
    double packet_recv_rate;
    uint64_t packet_counter_set;

    double packet_send_rate;
    uint32_t packets_left;
    uint64_t last_packets_left_set;

    double dropped, drop_ignore, rate_increase, last_send_rate;
    uint64_t drop_ignore_start, rate_increase_stop_start;
    uint32_t packets_resent, last_queue_size, packets_sent, last_packets_sent;

    uint8_t sending; /* indicates if data is being sent or not. */

    uint8_t killed; /* set to 1 to kill the connection. */

    uint8_t status_tcp[MAX_TCP_CONNECTIONS]; /* set to one of STATUS_TCP_* */
    uint8_t con_number_tcp[MAX_TCP_CONNECTIONS];

    Node_format tcp_relays[MAX_TCP_RELAYS_PEER];
    uint16_t num_tcp_relays;

    uint8_t maximum_speed_reached;

    pthread_mutex_t mutex;
} Crypto_Connection;

typedef struct {
    IP_Port source;
    uint8_t public_key[crypto_box_PUBLICKEYBYTES]; /* The real public key of the peer. */
    uint8_t dht_public_key[crypto_box_PUBLICKEYBYTES]; /* The dht public key of the peer. */
    uint8_t recv_nonce[crypto_box_NONCEBYTES]; /* Nonce of received packets. */
    uint8_t peersessionpublic_key[crypto_box_PUBLICKEYBYTES]; /* The public key of the peer. */
    uint8_t *cookie;
    uint8_t cookie_length;
} New_Connection;

typedef struct {
    DHT *dht;

    Crypto_Connection *crypto_connections;
    TCP_Client_Connection *tcp_connections_new[MAX_TCP_CONNECTIONS];
    TCP_Client_Connection *tcp_connections[MAX_TCP_CONNECTIONS];

    pthread_mutex_t connections_mutex;
    unsigned int connection_use_counter;

    uint32_t crypto_connections_length; /* Length of connections array. */

    /* Our public and secret keys. */
    uint8_t self_public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t self_secret_key[crypto_box_SECRETKEYBYTES];

    /* The secret key used for cookies */
    uint8_t secret_symmetric_key[crypto_box_KEYBYTES];

    int (*new_connection_callback)(void *object, New_Connection *n_c);
    void *new_connection_callback_object;

    /* The current optimal sleep time */
    uint32_t current_sleep_time;

    BS_LIST ip_port_list;
} Net_Crypto;


/* Set function to be called when someone requests a new connection to us.
 *
 * The set function should return -1 on failure and 0 on success.
 *
 * n_c is only valid for the duration of the function call.
 */
void new_connection_handler(Net_Crypto *c, int (*new_connection_callback)(void *object, New_Connection *n_c),
                            void *object);

/* Accept a crypto connection.
 *
 * return -1 on failure.
 * return connection id on success.
 */
int accept_crypto_connection(Net_Crypto *c, New_Connection *n_c);

/* Create a crypto connection.
 * If one to that real public key already exists, return it.
 *
 * return -1 on failure.
 * return connection id on success.
 */
int new_crypto_connection(Net_Crypto *c, const uint8_t *real_public_key);

/* Copy friends DHT public key into dht_key.
 *
 * return 0 on failure (no key copied).
 * return timestamp on success (key copied).
 */
uint64_t get_connection_dht_key(const Net_Crypto *c, int crypt_connection_id, uint8_t *dht_public_key);

/* Set the DHT public key of the crypto connection.
 * timestamp is the time (current_time_monotonic()) at which the key was last confirmed belonging to
 * the other peer.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int set_connection_dht_public_key(const Net_Crypto *c, int crypt_connection_id, const uint8_t *dht_public_key,
                                  uint64_t timestamp);

/* Set the direct ip of the crypto connection.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int set_direct_ip_port(Net_Crypto *c, int crypt_connection_id, IP_Port ip_port);

/* Set function to be called when connection with crypt_connection_id goes connects/disconnects.
 *
 * The set function should return -1 on failure and 0 on success.
 * Note that if this function is set, the connection will clear itself on disconnect.
 * Object and id will be passed to this function untouched.
 * status is 1 if the connection is going online, 0 if it is going offline.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int connection_status_handler(const Net_Crypto *c, int crypt_connection_id,
                              int (*connection_status_callback)(void *object, int id, uint8_t status), void *object, int id);

/* Set function to be called when connection with crypt_connection_id receives a lossless data packet of length.
 *
 * The set function should return -1 on failure and 0 on success.
 * Object and id will be passed to this function untouched.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int connection_data_handler(const Net_Crypto *c, int crypt_connection_id, int (*connection_data_callback)(void *object,
                            int id, uint8_t *data, uint16_t length), void *object, int id);


/* Set function to be called when connection with crypt_connection_id receives a lossy data packet of length.
 *
 * The set function should return -1 on failure and 0 on success.
 * Object and id will be passed to this function untouched.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int connection_lossy_data_handler(Net_Crypto *c, int crypt_connection_id,
                                  int (*connection_lossy_data_callback)(void *object, int id, const uint8_t *data, uint16_t length), void *object,
                                  int id);

/* returns the number of packet slots left in the sendbuffer.
 * return 0 if failure.
 */
uint32_t crypto_num_free_sendqueue_slots(const Net_Crypto *c, int crypt_connection_id);

/* Sends a lossless cryptopacket.
 *
 * return -1 if data could not be put in packet queue.
 * return positive packet number if data was put into the queue.
 *
 * The first byte of data must be in the CRYPTO_RESERVED_PACKETS to PACKET_ID_LOSSY_RANGE_START range.
 */
int64_t write_cryptpacket(const Net_Crypto *c, int crypt_connection_id, const uint8_t *data, uint32_t length);

/* return -1 on failure.
 * return 0 on success.
 *
 * Sends a lossy cryptopacket. (first byte must in the PACKET_ID_LOSSY_RANGE_*)
 */
int send_lossy_cryptpacket(Net_Crypto *c, int crypt_connection_id, const uint8_t *data, uint32_t length);

/* Add a tcp relay, associating it to a crypt_connection_id.
 *
 * return 0 if it was added.
 * return -1 if it wasn't.
 */
int add_tcp_relay_peer(Net_Crypto *c, int crypt_connection_id, IP_Port ip_port, const uint8_t *public_key);

/* Add a tcp relay to the array.
 *
 * return 0 if it was added.
 * return -1 if it wasn't.
 */
int add_tcp_relay(Net_Crypto *c, IP_Port ip_port, const uint8_t *public_key);

/* Copy a maximum of num TCP relays we are connected to to tcp_relays.
 * NOTE that the family of the copied ip ports will be set to TCP_INET or TCP_INET6.
 *
 * return number of relays copied to tcp_relays on success.
 * return 0 on failure.
 */
unsigned int copy_connected_tcp_relays(const Net_Crypto *c, Node_format *tcp_relays, uint16_t num);

/* Kill a crypto connection.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int crypto_kill(Net_Crypto *c, int crypt_connection_id);


/* return one of CRYPTO_CONN_* values indicating the state of the connection.
 *
 * sets direct_connected to 1 if connection connects directly to other, 0 if it isn't.
 */
unsigned int crypto_connection_status(const Net_Crypto *c, int crypt_connection_id, uint8_t *direct_connected);


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

/* Save the public and private keys to the keys array.
 *  Length must be crypto_box_PUBLICKEYBYTES + crypto_box_SECRETKEYBYTES.
 */
void save_keys(const Net_Crypto *c, 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(Net_Crypto *c, const uint8_t *keys);

/* Create new instance of Net_Crypto.
 *  Sets all the global connection variables to their default values.
 */
Net_Crypto *new_net_crypto(DHT *dht);

/* return the optimal interval in ms for running do_net_crypto.
 */
uint32_t crypto_run_interval(const Net_Crypto *c);

/* Main loop. */
void do_net_crypto(Net_Crypto *c);

void kill_net_crypto(Net_Crypto *c);



#endif