rust-gamedig/src/protocols/minecraft/protocol/java.rs

use serde_json::Value;
use crate::{GDError, GDResult};
use crate::protocols::minecraft::{as_varint, get_string, get_varint, Player, Response, Server};
use crate::protocols::types::TimeoutSettings;
use crate::socket::{Socket, TcpSocket};

pub struct Java {
    socket: TcpSocket
}

impl Java {
    fn new(address: &str, port: u16, timeout_settings: Option<TimeoutSettings>) -> GDResult<Self> {
        let socket = TcpSocket::new(address, port)?;
        socket.apply_timeout(timeout_settings)?;

        Ok(Self {
            socket
        })
    }

    fn send(&mut self, data: Vec<u8>) -> GDResult<()> {
        self.socket.send(&[as_varint(data.len() as i32), data].concat())
    }

    fn receive(&mut self) -> GDResult<Vec<u8>> {
        let buf = self.socket.receive(None)?;
        let mut pos = 0;

        let _packet_length = get_varint(&buf, &mut pos)? as usize;
        //this declared 'packet length' from within the packet might be wrong (?), not checking with it...

        Ok(buf[pos..].to_vec())
    }

    fn send_handshake(&mut self) -> GDResult<()> {
        self.send([
            //Packet ID (0)
            0x00,
            //Protocol Version (-1 to determine version)
            0xFF, 0xFF, 0xFF, 0xFF, 0x0F,
            //Server address (can be anything)
            0x07, 0x47, 0x61, 0x6D, 0x65, 0x44, 0x69, 0x67,
            //Server port (can be anything)
            0x00, 0x00,
            //Next state (1 for status)
            0x01].to_vec())?;

        Ok(())
    }

    fn send_status_request(&mut self) -> GDResult<()> {
        self.send([
            //Packet ID (0)
            0x00].to_vec())?;

        Ok(())
    }

    fn send_ping_request(&mut self) -> GDResult<()> {
        self.send([
            //Packet ID (1)
            0x01].to_vec())?;

        Ok(())
    }

    fn get_info(&mut self) -> GDResult<Response> {
        self.send_handshake()?;
        self.send_status_request()?;
        self.send_ping_request()?;

        let buf = self.receive()?;
        let mut pos = 0;

        if get_varint(&buf, &mut pos)? != 0 { //first var int is the packet id
            return Err(GDError::PacketBad("Bad receive packet id.".to_string()));
        }

        let json_response = get_string(&buf, &mut pos)?;
        let value_response: Value = serde_json::from_str(&json_response)
            .map_err(|e| GDError::JsonParse(e.to_string()))?;

        let version_name = value_response["version"]["name"].as_str()
            .ok_or(GDError::PacketBad("Couldn't get expected string.".to_string()))?.to_string();
        let version_protocol = value_response["version"]["protocol"].as_i64()
            .ok_or(GDError::PacketBad("Couldn't get expected number.".to_string()))? as i32;

        let max_players = value_response["players"]["max"].as_u64()
            .ok_or(GDError::PacketBad("Couldn't get expected number.".to_string()))? as u32;
        let online_players = value_response["players"]["online"].as_u64()
            .ok_or(GDError::PacketBad("Couldn't get expected number.".to_string()))? as u32;
        let sample_players: Option<Vec<Player>> = match value_response["players"]["sample"].is_null() {
            true => None,
            false => Some({
                let players_values = value_response["players"]["sample"].as_array()
                    .ok_or(GDError::PacketBad("Couldn't get expected array.".to_string()))?;

                let mut players = Vec::with_capacity(players_values.len());
                for player in players_values {
                    players.push(Player {
                        name: player["name"].as_str().ok_or(GDError::PacketBad("Couldn't get expected string.".to_string()))?.to_string(),
                        id: player["id"].as_str().ok_or(GDError::PacketBad("Couldn't get expected string.".to_string()))?.to_string()
                    })
                }

                players
            })
        };

        Ok(Response {
            version_name,
            version_protocol,
            max_players,
            online_players,
            sample_players,
            description: value_response["description"].to_string(),
            favicon: value_response["favicon"].as_str().map(str::to_string),
            previews_chat: value_response["previewsChat"].as_bool(),
            enforces_secure_chat: value_response["enforcesSecureChat"].as_bool(),
            server_type: Server::Java
        })
    }

    pub fn query(address: &str, port: u16, timeout_settings: Option<TimeoutSettings>) -> GDResult<Response> {
        Java::new(address, port, timeout_settings)?.get_info()
    }
}