why2-chat 2.1.0

/*
This is part of WHY2
Copyright (C) 2022-2026 Václav Šmejkal

This program 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.

This program 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 this program.  If not, see <https://www.gnu.org/licenses/>.
*/

use std::
{
    sync::Arc,
    time::Duration,
};

use tokio::
{
    sync::Mutex,
    net::tcp::{ OwnedReadHalf, OwnedWriteHalf },
};

use zeroize::Zeroizing;

use wincode::config::Configuration;

//CONSTS
pub const METADATA_URL: &str           = "https://crates.io/api/v1/crates/why2-chat"; //URL FOR PROJECT METADATA

pub const CONFIG_DIR: &str             = env!("WHY2_CONFIG_DIR");                     //DIRECTORY FOR CONFIG FILES
pub const UPLOADS_DIR: &str            = "WHY2-Uploads";                              //DIRECTORY FOR FILE UPLOADS
pub const SERVER_CONFIG: &str          = "/server.toml";                              //SERVER CONFIG FILE
pub const CLIENT_CONFIG: &str          = "/client.toml";                              //CLIENT CONFIG FILE
pub const SERVER_USERS_CONFIG: &str    = "/server_users.toml";                        //SERVER USERS CONFIG FILE
pub const SERVER_BANS_CONFIG: &str     = "/server_bans.toml";                         //SERVER BANS CONFIG FILE
pub const SERVER_MESSAGES_FILE: &str   = "/server_messages.bin";                      //SERVER MESSAGE HISTORY FILE
pub const SERVER_IMAGES_DIR: &str      = "/images";                                   //PERSISTENT IMAGE DIRECTORY

pub const SERVER_KEYS_CONFIG: &str     = "/server_keys.toml";                         //SERVER PUBKEY CONFIG FILE
pub const SERVER_KEYS_DIR: &str        = "/server_keys";                              //SERVER KEYS DIRECTORY
pub const SERVER_SKEY: &str            = "/private";                                  //SERVER PRIVATE KEY FILE
pub const SERVER_PKEY: &str            = "/public";                                   //SERVER PUBLIC KEY FILE
pub const SERVER_HISTORY_KEY: &str     = "/history_key";                              //MESSAGE HISTORY AT-REST KEY FILE
pub const SERVER_IMAGE_KEY: &str       = "/image_key";                                //PERSISTENT IMAGE KEY FILE

pub const ECC_PUBKEY_SIZE: usize       = 133;                                         //SEC1 UNCOMPRESSED NIST P-521 POINT
pub const ECC_SIGNATURE_SIZE: usize    = 132;                                         //FIXED-SIZE ECDSA/P-521 SIGNATURE (r || s)
pub const PQ_PUBKEY_SIZE: usize        = 1184;                                        //ML-KEM-768 ENCAPSULATION KEY
pub const PQ_CIPHERTEXT_SIZE: usize    = 1088;                                        //ML-KEM-768 CIPHERTEXT
pub const KEX_CONTEXT: &[u8]           = b"WHY2-KEX-V1";                              //DOMAIN SEPARATION FOR THE SIGNED HANDSHAKE TRANSCRIPT

pub const FETCH_TIMEOUT: u64           = 5000;                                        //TIMOUT FOR FETCHING DATA (MS)
pub const CONNECT_TIMEOUT: u64         = 3000;                                        //TIMEOUT FOR DIALING A SERVER (MS)

pub const MAX_HANDSHAKES_PER_IP: usize = 8;                                           //MAX CONCURRENT HANDSKAKES PER IP
pub const REKEY_INTERVAL: u64          = 600;                                         //INTERVAL FOR RE-REKEYING (SECS)

pub const EVENT_CHANNEL_BOUND: usize   = 1024;                                        //CLIENT UI EVENT BUFFER

pub const SERVER_RESTART_SETTINGS: &[&str] =                                          //SERVER SETTINGS THAT REQUIRE
    &["server_ip", "server_port", "enable_voice_chat", "server_username"];            //RESTART TO BE APPLIED

//DO NOT CHANGE CONSTS BELOW UNLESS YOU ARE ABSOLUTELY SURE WHAT ARE YOU DOING
pub const MEGABYTE: usize              = 1_000_000;                                   //MEGABYTE DEFINITION
pub const UPLOAD_CHUNK_SIZE: usize     = MEGABYTE;                                    //FILE UPLOAD CHUNK (1MB)
pub const IMAGE_HEADER_SIZE: usize     = 16;                                          //BYTES AN IMAGE IS RECOGNISED BY
pub const MAX_IMAGE_SIZE: usize        = 8 * MEGABYTE;                                //BIGGEST IMAGE THE SERVER PASSES ON (8MB)
pub const MAX_HISTORY_SIZE: usize      = 12 * MEGABYTE;                               //BIGGEST HISTORY THE SERVER REPLAYS (12MB)
pub const MAX_IMAGE_DIMENSION: u32     = 16_384;                                      //WIDEST/TALLEST PICTURE A CLIENT DECODES
pub const MAX_IMAGE_ALLOC: u64         = 256 * MEGABYTE as u64;                       //MOST MEMORY ONE DECODE MAY TAKE (256MB)

pub const IMAGE_REQUEST_DELAY: Duration    = Duration::from_millis(500);              //SPACING OF ONE CLIENT'S IMAGE FETCHES

pub const MAX_AUXILIARY_PACKET_SIZE: usize = UPLOAD_CHUNK_SIZE * 2;                   //FILE/SCREEN SIDE CHANNELS (2MB)
pub const MAX_PACKET_CEILING: usize        = 16 * MEGABYTE;                           //ABSOLUTE CEILING WHEN SPAM PROTECTION IS OFF (16MB)

pub type PacketConfig = Configuration<true, MAX_PACKET_CEILING>;

pub const PACKET_CONFIG: PacketConfig =
    Configuration::default().with_preallocation_size_limit::<MAX_PACKET_CEILING>();

//TYPES
pub type SharedKeys  = (Zeroizing<Vec<i64>>, Zeroizing<Vec<u8>>);           //WHY2 KEY, HMAC
pub type Streams<'a> = (&'a mut OwnedReadHalf, Arc<Mutex<OwnedWriteHalf>>); //READ STREAM, WRITE STREAM