/*
* onion_client.h -- Implementation of the client part of docs/Prevent_Tracking.txt
*                   (The part that uses the onion stuff to connect to the friend)
*
*  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 ONION_CLIENT_H
#define ONION_CLIENT_H

#include "onion_announce.h"
#include "net_crypto.h"
#include "ping_array.h"

#define MAX_ONION_CLIENTS 8
#define ONION_NODE_PING_INTERVAL 30
#define ONION_NODE_TIMEOUT (ONION_NODE_PING_INTERVAL * 4)

/* The interval in seconds at which to tell our friends where we are */
#define ONION_FAKEID_INTERVAL 30
#define DHT_FAKEID_INTERVAL 20

#define NUMBER_ONION_PATHS 3

/* The timeout the first time the path is added and
   then for all the next consecutive times */
#define ONION_PATH_FIRST_TIMEOUT 5
#define ONION_PATH_TIMEOUT 30
#define ONION_PATH_MAX_LIFETIME 600

/* A cheap way of making it take less bandwidth at startup:
   by limiting the number of ping packets we can send per
   second per peer. */
#define MAX_PING_NODES_SECOND_PEER 5

#define MAX_STORED_PINGED_NODES 9
#define MIN_NODE_PING_TIME 10

typedef struct {
    uint8_t     client_id[CLIENT_ID_SIZE];
    IP_Port     ip_port;
    uint8_t     ping_id[ONION_PING_ID_SIZE];
    uint8_t     data_public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t     is_stored;

    uint64_t    timestamp;

    uint64_t    last_pinged;

    uint32_t    path_used;
} Onion_Node;

typedef struct {
    Onion_Path paths[NUMBER_ONION_PATHS];
    uint64_t last_path_success[NUMBER_ONION_PATHS];
    uint64_t path_creation_time[NUMBER_ONION_PATHS];
} Onion_Client_Paths;

typedef struct {
    uint8_t     client_id[CLIENT_ID_SIZE];
    uint64_t    timestamp;
} Last_Pinged;

typedef struct {
    uint8_t status; /* 0 if friend is not valid, 1 if friend is valid.*/
    uint8_t is_online; /* Set by the onion_set_friend_status function. */

    uint8_t is_fake_clientid; /* 0 if we don't know the fake client id of the other 1 if we do. */
    uint64_t fake_client_id_timestamp;
    uint8_t fake_client_id[crypto_box_PUBLICKEYBYTES];
    uint8_t real_client_id[crypto_box_PUBLICKEYBYTES];

    Onion_Node clients_list[MAX_ONION_CLIENTS];
    uint8_t temp_public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t temp_secret_key[crypto_box_SECRETKEYBYTES];

    uint64_t last_fakeid_onion_sent;
    uint64_t last_fakeid_dht_sent;

    uint64_t last_noreplay;

    uint64_t last_seen;

    Onion_Client_Paths onion_paths;
    uint32_t ping_nodes_sent_second;

    Last_Pinged last_pinged[MAX_STORED_PINGED_NODES];
    uint8_t last_pinged_index;

    int (*tcp_relay_node_callback)(void *object, uint32_t number, IP_Port ip_port, uint8_t *public_key);
    void *tcp_relay_node_callback_object;
    uint32_t tcp_relay_node_callback_number;
} Onion_Friend;

typedef int (*oniondata_handler_callback)(void *object, uint8_t *source_pubkey, uint8_t *data, uint32_t len);

typedef struct {
    DHT     *dht;
    Net_Crypto *c;
    Networking_Core *net;
    Onion_Friend    *friends_list;
    uint16_t       num_friends;

    Onion_Node clients_announce_list[MAX_ONION_CLIENTS];

    Onion_Client_Paths onion_paths;

    uint8_t secret_symmetric_key[crypto_box_KEYBYTES];
    uint64_t last_run;

    uint8_t temp_public_key[crypto_box_PUBLICKEYBYTES];
    uint8_t temp_secret_key[crypto_box_SECRETKEYBYTES];

    uint32_t ping_nodes_sent_second;

    Last_Pinged last_pinged[MAX_STORED_PINGED_NODES];

    Ping_Array announce_ping_array;
    uint8_t last_pinged_index;
    struct {
        oniondata_handler_callback function;
        void *object;
    } Onion_Data_Handlers[256];
} Onion_Client;

/* Add a friend who we want to connect to.
 *
 * return -1 on failure.
 * return the friend number on success or if the friend was already added.
 */
int onion_friend_num(Onion_Client *onion_c, uint8_t *client_id);

/* Add a friend who we want to connect to.
 *
 * return -1 on failure.
 * return the friend number on success.
 */
int onion_addfriend(Onion_Client *onion_c, uint8_t *client_id);

/* Delete a friend.
 *
 * return -1 on failure.
 * return the deleted friend number on success.
 */
int onion_delfriend(Onion_Client *onion_c, int friend_num);

/* Set if friend is online or not.
 * NOTE: This function is there and should be used so that we don't send useless packets to the friend if he is online.
 *
 * is_online 1 means friend is online.
 * is_online 0 means friend is offline
 *
 * return -1 on failure.
 * return 0 on success.
 */
int onion_set_friend_online(Onion_Client *onion_c, int friend_num, uint8_t is_online);

/* Get the ip of friend friendnum and put it in ip_port
 *
 *  return -1, -- if client_id does NOT refer to a friend
 *  return  0, -- if client_id refers to a friend and we failed to find the friend (yet)
 *  return  1, ip if client_id refers to a friend and we found him
 *
 */
int onion_getfriendip(Onion_Client *onion_c, int friend_num, IP_Port *ip_port);

/* Set the function for this friend that will be callbacked with object and number
 * when that friends gives us one of the TCP relays he is connected to.
 *
 * object and number will be passed as argument to this function.
 *
 * return -1 on failure.
 * return 0 on success.
 */
int recv_tcp_relay_handler(Onion_Client *onion_c, int friend_num, int (*tcp_relay_node_callback)(void *object,
                           uint32_t number, IP_Port ip_port, uint8_t *public_key), void *object, uint32_t number);

/* Set a friends DHT public key.
 * 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 onion_set_friend_DHT_pubkey(Onion_Client *onion_c, int friend_num, uint8_t *dht_key, uint64_t timestamp);

/* Copy friends DHT public key into dht_key.
 *
 * return 0 on failure (no key copied).
 * return timestamp on success (key copied).
 */
uint64_t onion_getfriend_DHT_pubkey(Onion_Client *onion_c, int friend_num, uint8_t *dht_key);

#define ONION_DATA_IN_RESPONSE_MIN_SIZE (crypto_box_PUBLICKEYBYTES + crypto_box_MACBYTES)
#define ONION_CLIENT_MAX_DATA_SIZE (MAX_DATA_REQUEST_SIZE - ONION_DATA_IN_RESPONSE_MIN_SIZE)

/* Send data of length length to friendnum.
 * Maximum length of data is ONION_CLIENT_MAX_DATA_SIZE.
 * This data will be received by the friend using the Onion_Data_Handlers callbacks.
 *
 * Even if this function succeeds, the friend might not receive any data.
 *
 * return the number of packets sent on success
 * return -1 on failure.
 */
int send_onion_data(Onion_Client *onion_c, int friend_num, uint8_t *data, uint32_t length);

/* Function to call when onion data packet with contents beginning with byte is received. */
void oniondata_registerhandler(Onion_Client *onion_c, uint8_t byte, oniondata_handler_callback cb, void *object);

void do_onion_client(Onion_Client *onion_c);

Onion_Client *new_onion_client(Net_Crypto *c);

void kill_onion_client(Onion_Client *onion_c);

#endif