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

 * Copyright © 2019-2022 The TokTok team.

 */

#ifndef C_TOXCORE_TOXCORE_FORWARDING_H

#define C_TOXCORE_TOXCORE_FORWARDING_H

#include "DHT.h"

#include "network.h"

#ifdef __cplusplus

extern "C" {

#endif

#define SENDBACK_IPPORT 0

#define SENDBACK_FORWARD 1

#define SENDBACK_TCP 2

#define MAX_SENDBACK_SIZE (0xff - 1)

#define MAX_FORWARD_DATA_SIZE (MAX_UDP_PACKET_SIZE - (1 + 1 + MAX_SENDBACK_SIZE))

#define MAX_FORWARD_CHAIN_LENGTH 4

#define MAX_PACKED_IPPORT_SIZE (1 + SIZE_IP6 + sizeof(uint16_t))

typedef struct Forwarding Forwarding;

non_null()

DHT *forwarding_get_dht(const Forwarding *forwarding);

/**

 * @brief Send data to forwarder for forwarding via chain of dht nodes.

 * Destination is last key in the chain.

 *

 * @param data Must be of length at most MAX_FORWARD_DATA_SIZE.

 * @param chain_length Number of intermediate nodes in chain.

 *   Must be at least 1 and at most MAX_FORWARD_CHAIN_LENGTH.

 * @param chain_keys Public keys of chain nodes. Must be of length

 *   `chain_length * CRYPTO_PUBLIC_KEY_SIZE`.

 *

 * @return true on success, false otherwise.

 */

non_null()

bool send_forward_request(const Networking_Core *net, const IP_Port *forwarder,

                          const uint8_t *chain_keys, uint16_t chain_length,

                          const uint8_t *data, uint16_t data_length);

/** Returns size of packet written by create_forward_chain_packet. */

uint16_t forward_chain_packet_size(uint16_t chain_length, uint16_t data_length);

/**

 * @brief Create forward request packet for forwarding data via chain of dht nodes.

 * Destination is last key in the chain.

 *

 * @param data Must be of length at most MAX_FORWARD_DATA_SIZE.

 * @param chain_length Number of intermediate nodes in chain.

 *   Must be at least 1 and at most MAX_FORWARD_CHAIN_LENGTH.

 * @param chain_keys Public keys of chain nodes. Must be of length

 *   `chain_length * CRYPTO_PUBLIC_KEY_SIZE`.

 * @param packet Must be of size at least

 *   `forward_chain_packet_size(chain_length, data_length)` bytes.

 *

 * @return true on success, false otherwise.

 */

non_null()

bool create_forward_chain_packet(const uint8_t *chain_keys, uint16_t chain_length,

                                 const uint8_t *data, uint16_t data_length,

                                 uint8_t *packet);

/**

 * @brief Send reply to forwarded packet via forwarder.

 * @param sendback Must be of size at most MAX_SENDBACK_SIZE.

 * @param data Must be of size at most MAX_FORWARD_DATA_SIZE.

 *

 * @return true on success, false otherwise.

 */

non_null()

bool forward_reply(const Networking_Core *net, const IP_Port *forwarder,

                   const uint8_t *sendback, uint16_t sendback_length,

                   const uint8_t *data, uint16_t length);

/**

 * @brief Set callback to handle a forwarded request.

 * To reply to the packet, callback should use `forward_reply()` to send a reply

 * forwarded via forwarder, passing the provided sendback.

 */

typedef void forwarded_request_cb(void *object, const IP_Port *forwarder, const uint8_t *sendback,

                                  uint16_t sendback_length, const uint8_t *data,

                                  uint16_t length, void *userdata);

non_null(1) nullable(2, 3)

void set_callback_forwarded_request(Forwarding *forwarding, forwarded_request_cb *function, void *object);

/** @brief Set callback to handle a forwarded response. */

typedef void forwarded_response_cb(void *object, const uint8_t *data, uint16_t length, void *userdata);

non_null(1) nullable(2, 3)

void set_callback_forwarded_response(Forwarding *forwarding, forwarded_response_cb *function, void *object);

/** @brief Send forwarding packet to dest with given sendback data and data. */

non_null(1, 2, 5) nullable(3)

bool send_forwarding(const Forwarding *forwarding, const IP_Port *dest,

                     const uint8_t *sendback_data, uint16_t sendback_data_len,

                     const uint8_t *data, uint16_t length);

typedef bool forward_reply_cb(void *object, const uint8_t *sendback_data, uint16_t sendback_data_len,

                              const uint8_t *data, uint16_t length);

/**

 * @brief Set callback to handle a forward reply with an otherwise unhandled

 * sendback.

 */

non_null(1) nullable(2, 3)

void set_callback_forward_reply(Forwarding *forwarding, forward_reply_cb *function, void *object);

non_null()

Forwarding *new_forwarding(const Logger *log, const Random *rng, const Mono_Time *mono_time, DHT *dht);

nullable(1)

void kill_forwarding(Forwarding *forwarding);

#ifdef __cplusplus

} /* extern "C" */

#endif

#endif /* C_TOXCORE_TOXCORE_FORWARDING_H */