/* SPDX-License-Identifier: GPL-3.0-or-later

 * Copyright © 2016-2018 The TokTok team.

 * Copyright © 2013 Tox project.

 * Copyright © 2013 plutooo

 */

/**

 * Buffered pinging using cyclic arrays.

 */

#include "ping.h"

#include <string.h>

#include "DHT.h"

#include "ccompat.h"

#include "crypto_core.h"

#include "mem.h"

#include "mono_time.h"

#include "network.h"

#include "ping_array.h"

#define PING_NUM_MAX 512

/** Maximum newly announced nodes to ping per TIME_TO_PING seconds. */

#define MAX_TO_PING 32

/** Ping newly announced nodes to ping per TIME_TO_PING seconds*/

#define TIME_TO_PING 2

struct Ping {

    const Mono_Time *mono_time;

    const Random *rng;

    DHT *dht;

    Ping_Array  *ping_array;

    Node_format to_ping[MAX_TO_PING];

    uint64_t    last_to_ping;

};

#define PING_PLAIN_SIZE (1 + sizeof(uint64_t))

#define DHT_PING_SIZE (1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE + PING_PLAIN_SIZE + CRYPTO_MAC_SIZE)

#define PING_DATA_SIZE (CRYPTO_PUBLIC_KEY_SIZE + sizeof(IP_Port))

void ping_send_request(Ping *ping, const IP_Port *ipp, const uint8_t *public_key)

{

    uint8_t   pk[DHT_PING_SIZE];

    int       rc;

    uint64_t  ping_id;

    if (pk_equal(public_key, dht_get_self_public_key(ping->dht))) {

        return;

    }

    // generate key to encrypt ping_id with recipient privkey

    const uint8_t *shared_key = dht_get_shared_key_sent(ping->dht, public_key);

    // Generate random ping_id.

    uint8_t data[PING_DATA_SIZE];

    pk_copy(data, public_key);

    memcpy(data + CRYPTO_PUBLIC_KEY_SIZE, ipp, sizeof(IP_Port));

    ping_id = ping_array_add(ping->ping_array, ping->mono_time, ping->rng, data, sizeof(data));

    if (ping_id == 0) {

        return;

    }

    uint8_t ping_plain[PING_PLAIN_SIZE];

    ping_plain[0] = NET_PACKET_PING_REQUEST;

    memcpy(ping_plain + 1, &ping_id, sizeof(ping_id));

    pk[0] = NET_PACKET_PING_REQUEST;

    pk_copy(pk + 1, dht_get_self_public_key(ping->dht));     // Our pubkey

    random_nonce(ping->rng, pk + 1 + CRYPTO_PUBLIC_KEY_SIZE); // Generate new nonce

    rc = encrypt_data_symmetric(shared_key,

                                pk + 1 + CRYPTO_PUBLIC_KEY_SIZE,

                                ping_plain, sizeof(ping_plain),

                                pk + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE);

    if (rc != PING_PLAIN_SIZE + CRYPTO_MAC_SIZE) {

        return;

    }

    // We never check this return value and failures in sendpacket are already logged

    sendpacket(dht_get_net(ping->dht), ipp, pk, sizeof(pk));

}

non_null()

static int ping_send_response(const Ping *ping, const IP_Port *ipp, const uint8_t *public_key,

                              uint64_t ping_id, const uint8_t *shared_encryption_key)

{

    uint8_t pk[DHT_PING_SIZE];

    if (pk_equal(public_key, dht_get_self_public_key(ping->dht))) {

        return 1;

    }

    uint8_t ping_plain[PING_PLAIN_SIZE];

    ping_plain[0] = NET_PACKET_PING_RESPONSE;

    memcpy(ping_plain + 1, &ping_id, sizeof(ping_id));

    pk[0] = NET_PACKET_PING_RESPONSE;

    pk_copy(pk + 1, dht_get_self_public_key(ping->dht));     // Our pubkey

    random_nonce(ping->rng, pk + 1 + CRYPTO_PUBLIC_KEY_SIZE); // Generate new nonce

    // Encrypt ping_id using recipient privkey

    const int rc = encrypt_data_symmetric(shared_encryption_key,

                                          pk + 1 + CRYPTO_PUBLIC_KEY_SIZE,

                                          ping_plain, sizeof(ping_plain),

                                          pk + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE);

    if (rc != PING_PLAIN_SIZE + CRYPTO_MAC_SIZE) {

        return 1;

    }

    return sendpacket(dht_get_net(ping->dht), ipp, pk, sizeof(pk));

}

non_null()

static int handle_ping_request(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length,

                               void *userdata)

{

    DHT *dht = (DHT *)object;

    if (length != DHT_PING_SIZE) {

        return 1;

    }

    Ping *ping = dht_get_ping(dht);

    if (pk_equal(packet + 1, dht_get_self_public_key(ping->dht))) {

        return 1;

    }

    const uint8_t *shared_key = dht_get_shared_key_recv(dht, packet + 1);

    uint8_t ping_plain[PING_PLAIN_SIZE];

    // Decrypt ping_id

    const int rc = decrypt_data_symmetric(shared_key,

                                          packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,

                                          packet + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE,

                                          PING_PLAIN_SIZE + CRYPTO_MAC_SIZE,

                                          ping_plain);

    if (rc != sizeof(ping_plain)) {

        return 1;

    }

    if (ping_plain[0] != NET_PACKET_PING_REQUEST) {

        return 1;

    }

    uint64_t ping_id;

    memcpy(&ping_id, ping_plain + 1, sizeof(ping_id));

    // Send response

    ping_send_response(ping, source, packet + 1, ping_id, shared_key);

    ping_add(ping, packet + 1, source);

    return 0;

}

non_null()

static int handle_ping_response(void *object, const IP_Port *source, const uint8_t *packet, uint16_t length,

                                void *userdata)

{

    DHT      *dht = (DHT *)object;

    int       rc;

    if (length != DHT_PING_SIZE) {

        return 1;

    }

    Ping *ping = dht_get_ping(dht);

    if (pk_equal(packet + 1, dht_get_self_public_key(ping->dht))) {

        return 1;

    }

    // generate key to encrypt ping_id with recipient privkey

    const uint8_t *shared_key = dht_get_shared_key_sent(ping->dht, packet + 1);

    uint8_t ping_plain[PING_PLAIN_SIZE];

    // Decrypt ping_id

    rc = decrypt_data_symmetric(shared_key,

                                packet + 1 + CRYPTO_PUBLIC_KEY_SIZE,

                                packet + 1 + CRYPTO_PUBLIC_KEY_SIZE + CRYPTO_NONCE_SIZE,

                                PING_PLAIN_SIZE + CRYPTO_MAC_SIZE,

                                ping_plain);

    if (rc != sizeof(ping_plain)) {

        return 1;

    }

    if (ping_plain[0] != NET_PACKET_PING_RESPONSE) {

        return 1;

    }

    uint64_t   ping_id;

    memcpy(&ping_id, ping_plain + 1, sizeof(ping_id));

    uint8_t data[PING_DATA_SIZE];

    if (ping_array_check(ping->ping_array, ping->mono_time, data, sizeof(data), ping_id) != sizeof(data)) {

        return 1;

    }

    if (!pk_equal(packet + 1, data)) {

        return 1;

    }

    IP_Port ipp;

    memcpy(&ipp, data + CRYPTO_PUBLIC_KEY_SIZE, sizeof(IP_Port));

    if (!ipport_equal(&ipp, source)) {

        return 1;

    }

    addto_lists(dht, source, packet + 1);

    return 0;

}

/** @brief Check if public_key with ip_port is in the list.

 *

 * return true if it is.

 * return false if it isn't.

 */

non_null()

static bool in_list(const Client_data *list, uint16_t length, const Mono_Time *mono_time, const uint8_t *public_key,

                    const IP_Port *ip_port)

{

    for (unsigned int i = 0; i < length; ++i) {

        if (pk_equal(list[i].public_key, public_key)) {

            const IPPTsPng *ipptp;

            if (net_family_is_ipv4(ip_port->ip.family)) {

                ipptp = &list[i].assoc4;

            } else {

                ipptp = &list[i].assoc6;

            }

            if (!mono_time_is_timeout(mono_time, ipptp->timestamp, BAD_NODE_TIMEOUT)

                    && ipport_equal(&ipptp->ip_port, ip_port)) {

                return true;

            }

        }

    }

    return false;

}

/** @brief Add nodes to the to_ping list.

 * All nodes in this list are pinged every TIME_TO_PING seconds

 * and are then removed from the list.

 * If the list is full the nodes farthest from our public_key are replaced.

 * The purpose of this list is to enable quick integration of new nodes into the

 * network while preventing amplification attacks.

 *

 * @retval 0 if node was added.

 * @retval -1 if node was not added.

 */

int32_t ping_add(Ping *ping, const uint8_t *public_key, const IP_Port *ip_port)

{

    if (!ip_isset(&ip_port->ip)) {

        return -1;

    }

    if (!node_addable_to_close_list(ping->dht, public_key, ip_port)) {

        return -1;

    }

    if (in_list(dht_get_close_clientlist(ping->dht), LCLIENT_LIST, ping->mono_time, public_key, ip_port)) {

        return -1;

    }

    IP_Port temp;

    if (dht_getfriendip(ping->dht, public_key, &temp) == 0) {

        ping_send_request(ping, ip_port, public_key);

        return -1;

    }

    for (unsigned int i = 0; i < MAX_TO_PING; ++i) {

        if (!ip_isset(&ping->to_ping[i].ip_port.ip)) {

            memcpy(ping->to_ping[i].public_key, public_key, CRYPTO_PUBLIC_KEY_SIZE);

            ipport_copy(&ping->to_ping[i].ip_port, ip_port);

            return 0;

        }

        if (pk_equal(ping->to_ping[i].public_key, public_key)) {

            return -1;

        }

    }

    if (add_to_list(ping->to_ping, MAX_TO_PING, public_key, ip_port, dht_get_self_public_key(ping->dht))) {

        return 0;

    }

    return -1;

}

/** @brief Ping all the valid nodes in the to_ping list every TIME_TO_PING seconds.

 * This function must be run at least once every TIME_TO_PING seconds.

 */

void ping_iterate(Ping *ping)

{

    if (!mono_time_is_timeout(ping->mono_time, ping->last_to_ping, TIME_TO_PING)) {

        return;

    }

    if (!ip_isset(&ping->to_ping[0].ip_port.ip)) {

        return;

    }

    unsigned int i;

    for (i = 0; i < MAX_TO_PING; ++i) {

        if (!ip_isset(&ping->to_ping[i].ip_port.ip)) {

            break;

        }

        if (!node_addable_to_close_list(ping->dht, ping->to_ping[i].public_key, &ping->to_ping[i].ip_port)) {

            continue;

        }

        ping_send_request(ping, &ping->to_ping[i].ip_port, ping->to_ping[i].public_key);

        ip_reset(&ping->to_ping[i].ip_port.ip);

    }

    if (i != 0) {

        ping->last_to_ping = mono_time_get(ping->mono_time);

    }

}

Ping *ping_new(const Memory *mem, const Mono_Time *mono_time, const Random *rng, DHT *dht)

{

    Ping *ping = (Ping *)mem_alloc(mem, sizeof(Ping));

    if (ping == nullptr) {

        return nullptr;

    }

    ping->ping_array = ping_array_new(mem, PING_NUM_MAX, PING_TIMEOUT);

    if (ping->ping_array == nullptr) {

        mem_delete(mem, ping);

        return nullptr;

    }

    ping->mono_time = mono_time;

    ping->rng = rng;

    ping->dht = dht;

    networking_registerhandler(dht_get_net(ping->dht), NET_PACKET_PING_REQUEST, &handle_ping_request, dht);

    networking_registerhandler(dht_get_net(ping->dht), NET_PACKET_PING_RESPONSE, &handle_ping_response, dht);

    return ping;

}

void ping_kill(const Memory *mem, Ping *ping)

{

    if (ping == nullptr) {

        return;

    }

    networking_registerhandler(dht_get_net(ping->dht), NET_PACKET_PING_REQUEST, nullptr, nullptr);

    networking_registerhandler(dht_get_net(ping->dht), NET_PACKET_PING_RESPONSE, nullptr, nullptr);

    ping_array_kill(ping->ping_array);

    mem_delete(mem, ping);

}