/*
 * Implementation of the TCP relay server part of Tox.
 */

/*
 * Copyright © 2016-2017 The TokTok team.
 * Copyright © 2014 Tox project.
 *
 * This file is part of Tox, the free peer to peer instant messenger.
 *
 * 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 TCP_SERVER_H
#define TCP_SERVER_H

#include "crypto_core.h"
#include "list.h"
#include "onion.h"

#ifdef TCP_SERVER_USE_EPOLL
#include <sys/epoll.h>
#endif

// Disable MSG_NOSIGNAL on systems not supporting it, e.g. Windows, FreeBSD
#if !defined(MSG_NOSIGNAL)
#define MSG_NOSIGNAL 0
#endif

#define MAX_INCOMING_CONNECTIONS 256

#define TCP_MAX_BACKLOG MAX_INCOMING_CONNECTIONS

#define MAX_PACKET_SIZE 2048

#define TCP_HANDSHAKE_PLAIN_SIZE (CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE)
#define TCP_SERVER_HANDSHAKE_SIZE (CRYPTO_NONCE_SIZE + TCP_HANDSHAKE_PLAIN_SIZE + CRYPTO_MAC_SIZE)
#define TCP_CLIENT_HANDSHAKE_SIZE (CRYPTO_PUBLIC_KEY_SIZE + TCP_SERVER_HANDSHAKE_SIZE)
#define TCP_MAX_OOB_DATA_LENGTH 1024

#define NUM_RESERVED_PORTS 16
#define NUM_CLIENT_CONNECTIONS (256 - NUM_RESERVED_PORTS)

#define TCP_PACKET_ROUTING_REQUEST  0
#define TCP_PACKET_ROUTING_RESPONSE 1
#define TCP_PACKET_CONNECTION_NOTIFICATION 2
#define TCP_PACKET_DISCONNECT_NOTIFICATION 3
#define TCP_PACKET_PING 4
#define TCP_PACKET_PONG 5
#define TCP_PACKET_OOB_SEND 6
#define TCP_PACKET_OOB_RECV 7
#define TCP_PACKET_ONION_REQUEST  8
#define TCP_PACKET_ONION_RESPONSE 9

#define ARRAY_ENTRY_SIZE 6

/* frequency to ping connected nodes and timeout in seconds */
#define TCP_PING_FREQUENCY 30
#define TCP_PING_TIMEOUT 10

#ifdef TCP_SERVER_USE_EPOLL
#define TCP_SOCKET_LISTENING 0
#define TCP_SOCKET_INCOMING 1
#define TCP_SOCKET_UNCONFIRMED 2
#define TCP_SOCKET_CONFIRMED 3
#endif

enum {
    TCP_STATUS_NO_STATUS,
    TCP_STATUS_CONNECTED,
    TCP_STATUS_UNCONFIRMED,
    TCP_STATUS_CONFIRMED,
};

typedef struct TCP_Priority_List TCP_Priority_List;

struct TCP_Priority_List {
    TCP_Priority_List *next;
    uint16_t size, sent;
    uint8_t data[];
};

typedef struct TCP_Secure_Connection {
    Socket sock;
    uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
    uint8_t recv_nonce[CRYPTO_NONCE_SIZE]; /* Nonce of received packets. */
    uint8_t sent_nonce[CRYPTO_NONCE_SIZE]; /* Nonce of sent packets. */
    uint8_t shared_key[CRYPTO_SHARED_KEY_SIZE];
    uint16_t next_packet_length;
    struct {
        uint8_t public_key[CRYPTO_PUBLIC_KEY_SIZE];
        uint32_t index;
        uint8_t status; /* 0 if not used, 1 if other is offline, 2 if other is online. */
        uint8_t other_id;
    } connections[NUM_CLIENT_CONNECTIONS];
    uint8_t last_packet[2 + MAX_PACKET_SIZE];
    uint8_t status;
    uint16_t last_packet_length;
    uint16_t last_packet_sent;

    TCP_Priority_List *priority_queue_start, *priority_queue_end;

    uint64_t identifier;

    uint64_t last_pinged;
    uint64_t ping_id;
} TCP_Secure_Connection;


typedef struct TCP_Server TCP_Server;

const uint8_t *tcp_server_public_key(const TCP_Server *tcp_server);
size_t tcp_server_listen_count(const TCP_Server *tcp_server);

/* Create new TCP server instance.
 */
TCP_Server *new_TCP_server(uint8_t ipv6_enabled, uint16_t num_sockets, const uint16_t *ports, const uint8_t *secret_key,
                           Onion *onion);

/* Run the TCP_server
 */
void do_TCP_server(TCP_Server *TCP_server);

/* Kill the TCP server
 */
void kill_TCP_server(TCP_Server *TCP_server);

/* return the amount of data in the tcp recv buffer.
 * return 0 on failure.
 */
unsigned int TCP_socket_data_recv_buffer(Socket sock);

/* Read the next two bytes in TCP stream then convert them to
 * length (host byte order).
 *
 * return length on success
 * return 0 if nothing has been read from socket.
 * return ~0 on failure.
 */
uint16_t read_TCP_length(Socket sock);

/* Read length bytes from socket.
 *
 * return length on success
 * return -1 on failure/no data in buffer.
 */
int read_TCP_packet(Socket sock, uint8_t *data, uint16_t length);

/* return length of received packet on success.
 * return 0 if could not read any packet.
 * return -1 on failure (connection must be killed).
 */
int read_packet_TCP_secure_connection(Socket sock, uint16_t *next_packet_length, const uint8_t *shared_key,
                                      uint8_t *recv_nonce, uint8_t *data, uint16_t max_len);


#endif