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

 * Copyright © 2016-2020 The TokTok team.

 * Copyright © 2015 Tox project.

 */

/**

 * An implementation of massive text only group chats.

 */

#ifndef C_TOXCORE_TOXCORE_GROUP_CONNECTION_H

#define C_TOXCORE_TOXCORE_GROUP_CONNECTION_H

#include "DHT.h"

#include "TCP_connection.h"

#include "attributes.h"

#include "crypto_core.h"

#include "group_common.h"

#include "logger.h"

#include "mem.h"

#include "mono_time.h"

#include "network.h"

/* Max number of TCP relays we share with a peer on handshake */

#define GCC_MAX_TCP_SHARED_RELAYS 3

/** Marks a peer for deletion. If gconn is null or already marked for deletion this function has no effect. */

void gcc_mark_for_deletion(GC_Connection *_Nonnull gconn, TCP_Connections *_Nonnull tcp_conn, Group_Exit_Type type,

                           const uint8_t *_Nullable part_message, uint16_t length);

/** @brief Decides if message need to be put in recv_array or immediately handled.

 *

 * Return 3 if message is in correct sequence and is a fragment packet.

 * Return 2 if message is in correct sequence and may be handled immediately.

 * Return 1 if packet is out of sequence and added to recv_array.

 * Return 0 if message is a duplicate.

 * Return -1 on failure

 */

int gcc_handle_received_message(const Logger *_Nonnull log, const Memory *_Nonnull mem, const Mono_Time *_Nonnull mono_time, GC_Connection *_Nonnull gconn,

                                const uint8_t *_Nullable data, uint16_t length, uint8_t packet_type, uint64_t message_id,

                                bool direct_conn);

/** @brief Handles a packet fragment.

 *

 * If the fragment is incomplete, it gets stored in the recv

 * array. Otherwise the segment is re-assembled into a complete

 * payload and processed.

 *

 * Return 1 if fragment is successfully handled and is not the end of the sequence.

 * Return 0 if fragment is the end of a sequence and successfully handled.

 * Return -1 on failure.

 */

int gcc_handle_packet_fragment(const GC_Session *_Nonnull c, GC_Chat *_Nonnull chat, uint32_t peer_number, GC_Connection *_Nonnull gconn,

                               const uint8_t *_Nullable chunk, uint16_t length, uint8_t packet_type, uint64_t message_id,

                               void *_Nullable userdata);

/** @brief Return array index for message_id */

uint16_t gcc_get_array_index(uint64_t message_id);

/** @brief Removes send_array item with message_id.

 *

 * Return true on success.

 */

bool gcc_handle_ack(const Logger *_Nonnull log, const Memory *_Nonnull mem, GC_Connection *_Nonnull gconn, uint64_t message_id);

/** @brief Sets the send_message_id and send_array_start for `gconn` to `id`.

 *

 * This should only be used to initialize a new lossless connection.

 */

void gcc_set_send_message_id(GC_Connection *_Nonnull gconn, uint64_t id);

/** @brief Sets the received_message_id for `gconn` to `id`. */

void gcc_set_recv_message_id(GC_Connection *_Nonnull gconn, uint64_t id);

/**

 * @brief Returns true if the ip_port is set for gconn.

 */

bool gcc_ip_port_is_set(const GC_Connection *_Nonnull gconn);

/**

 * @brief Sets the ip_port for gconn to ipp.

 *

 * If ipp is not set this function has no effect.

 */

void gcc_set_ip_port(GC_Connection *_Nonnull gconn, const IP_Port *_Nullable ipp);

/** @brief Copies a random TCP relay node from gconn to tcp_node.

 *

 * Return true on success.

 */

bool gcc_copy_tcp_relay(const Random *_Nonnull rng, Node_format *_Nonnull tcp_node, const GC_Connection *_Nonnull gconn);

/** @brief Saves tcp_node to gconn's list of connected tcp relays.

 *

 * If relays list is full a random node is overwritten with the new node.

 *

 * Return 0 on success.

 * Return -1 on failure.

 * Return -2 if node is already in list.

 */

int gcc_save_tcp_relay(const Random *_Nonnull rng, GC_Connection *_Nonnull gconn, const Node_format *_Nonnull tcp_node);

/** @brief Checks for and handles messages that are in proper sequence in gconn's recv_array.

 * This should always be called after a new packet is successfully handled.

 */

void gcc_check_recv_array(const GC_Session *_Nonnull c, GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn, uint32_t peer_number,

                          void *_Nullable userdata);

/** @brief Attempts to re-send lossless packets that have not yet received an ack. */

void gcc_resend_packets(const GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn);

/**

 * Uses public encryption key `sender_pk` and the shared secret key associated with `gconn`

 * to generate a shared 32-byte encryption key that can be used by the owners of both keys for symmetric

 * encryption and decryption.

 *

 * Puts the result in the shared session key buffer for `gconn`, which must have room for

 * CRYPTO_SHARED_KEY_SIZE bytes. This resulting shared key should be treated as a secret key.

 */

void gcc_make_session_shared_key(GC_Connection *_Nonnull gconn, const uint8_t *_Nonnull sender_pk);

/** @brief Return true if we have a direct connection with `gconn`. */

bool gcc_conn_is_direct(const Mono_Time *_Nonnull mono_time, const GC_Connection *_Nonnull gconn);

/** @brief Return true if we can try a direct connection with `gconn` again. */

bool gcc_conn_should_try_direct(const Mono_Time *_Nonnull mono_time, const GC_Connection *_Nonnull gconn);

/** @brief Return true if a direct UDP connection is possible with `gconn`. */

bool gcc_direct_conn_is_possible(const GC_Chat *_Nonnull chat, const GC_Connection *_Nonnull gconn);

/** @brief Sends a packet to the peer associated with gconn.

 *

 * This is a lower level function that does not encrypt or wrap the packet.

 *

 * Return true on success.

 */

bool gcc_send_packet(const GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn, const uint8_t *_Nonnull packet, uint16_t length);

/** @brief Sends a lossless packet to `gconn` comprised of `data` of size `length`.

 *

 * This function will add the packet to the lossless send array, encrypt/wrap it using the

 * shared key associated with `gconn`, and try to send it over the wire.

 *

 * Return 0 if the packet was successfully encrypted and added to the send array.

 * Return -1 if the packet couldn't be added to the send array.

 * Return -2 if the packet failed to be wrapped or encrypted.

 */

int gcc_send_lossless_packet(const GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn, const uint8_t *_Nullable data, uint16_t length,

                             uint8_t packet_type);

/** @brief Splits a lossless packet up into fragments, wraps each fragment in a GP_FRAGMENT

 * header, encrypts them, and send them in succession.

 *

 * This function will first try to add each packet fragment to the send array as an atomic

 * unit. If any chunk fails to be added the process will be reversed and an error will be

 * returned. Otherwise it will then try to send all the fragments in succession.

 *

 * Return true if all fragments are successfully added to the send array.

 */

bool gcc_send_lossless_packet_fragments(const GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn, const uint8_t *_Nonnull data, uint16_t length, uint8_t packet_type);

/** @brief Encrypts `data` of `length` bytes, designated by `message_id`, using the shared key

 * associated with `gconn` and sends lossless packet over the wire.

 *

 * This function does not add the packet to the send array.

 *

 * Return 0 on success.

 * Return -1 if packet wrapping and encryption fails.

 * Return -2 if the packet fails to send.

 */

int gcc_encrypt_and_send_lossless_packet(const GC_Chat *_Nonnull chat, GC_Connection *_Nonnull gconn, const uint8_t *_Nullable data,

        uint16_t length, uint64_t message_id, uint8_t packet_type);

/** @brief Called when a peer leaves the group. */

void gcc_peer_cleanup(const Memory *_Nonnull mem, GC_Connection *_Nonnull gconn);

/** @brief Called on group exit. */

void gcc_cleanup(const GC_Chat *_Nonnull chat);

#endif /* C_TOXCORE_TOXCORE_GROUP_CONNECTION_H */