Trying to get the ping to work

Cargo.toml

@@ -7,3 +7,5 @@ edition = "2021"
 
 [dependencies]
 tokio = { version = "1", features = ["full"] }
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"

src/handshake.rs

@@ -0,0 +1,44 @@
+// Yeahbut December 2023
+
+use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
+use crate::mc_types;
+
+pub struct Handshake {
+    pub protocol_version: i32,
+    pub server_address: String,
+    pub server_port: u16,
+    pub next_state: i32,
+}
+
+pub async fn read_handshake(stream: &mut OwnedReadHalf) -> Option<Handshake> {
+    Some(Handshake {
+        protocol_version: mc_types::read_var_int(stream)
+            .await,
+        server_address: mc_types::read_string(stream)
+            .await,
+        server_port: stream.read_u16()
+            .await.expect("Error reading from stream"),
+        next_state: mc_types::read_var_int(stream)
+            .await,
+    })
+}
+
+pub async fn write_handshake(
+    stream: &mut OwnedWriteHalf,
+    handshake: Handshake,
+) {
+    let mut data: Vec<u8> = vec![0];
+    mc_types::write_var_int_bytes(&mut data, handshake.protocol_version);
+    mc_types::write_string_bytes(&mut data, &handshake.server_address);
+    data.append(&mut vec![
+        ((handshake.server_port & 0xFF00) >> 8) as u8,
+        (handshake.server_port & 0xFF) as u8,
+    ]);
+    mc_types::write_var_int_bytes(&mut data, handshake.next_state);
+
+    mc_types::write_var_int(stream, data.len() as i32).await;
+    stream.write_all(&mut data)
+        .await.expect("Error writing to stream");
+}

src/login.rs

@@ -0,0 +1,6 @@
+// Yeahbut December 2023
+
+use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+
+use crate::mc_types;

src/main.rs

@@ -1,9 +1,14 @@
 // Yeahbut December 2023
 
 use tokio::net::{TcpListener, TcpStream};
-use tokio::io;
+use tokio::io::{self, AsyncReadExt}; //, AsyncWriteExt};
 use std::error::Error;
 
+mod mc_types;
+mod handshake;
+mod status;
+mod login;
+
 #[tokio::main]
 async fn main() -> Result<(), Box<dyn Error>> {
     let listener = TcpListener::bind("127.0.0.1:25565").await?;
@@ -17,26 +22,54 @@ async fn main() -> Result<(), Box<dyn Error>> {
 }
 
 async fn handle_client(client_socket: TcpStream) {
+    println!("Accepting Connection");
     let backend_addr = "127.0.0.1:25566";
 
-    if let Ok(mut backend_socket) = TcpStream::connect(backend_addr).await {
-        let (mut client_reader, mut client_writer) = client_socket.into_split();
-        let (mut backend_reader, mut backend_writer) = backend_socket.into_split();
+    let (mut client_reader, mut client_writer) = client_socket.into_split();
+    if let Ok(backend_socket) = TcpStream::connect(backend_addr).await {
+        let (mut server_reader, mut server_writer) = backend_socket.into_split();
+        let packet_id = client_reader.read_u8()
+            .await.expect("Error reading from stream");
+
+        println!("Packet ID: {}", packet_id);
+        if packet_id == 0 {
+            let handshake_packet = handshake::read_handshake(&mut client_reader)
+                .await.unwrap();
+            println!("Next state: {}", handshake_packet.next_state);
+            if handshake_packet.next_state == 1 {
+                println!("Receiving Status Request");
+                status::respond_status(
+                    &mut client_reader,
+                    &mut client_writer,
+                    &mut server_reader,
+                    &mut server_writer,
+                ).await;
+                return;
+            } else if handshake_packet.next_state == 2 {
+
+            } else {
+                return;
+            }
+        } else if packet_id == 0xFE {
+            status::respond_legacy_status(&mut client_writer).await;
+            return;
+        } else {
+            return;
+        }
 
         // Forward from client to backend
         tokio::spawn(async move {
-            if let Err(e) = io::copy(&mut client_reader, &mut backend_writer).await {
-                eprintln!("Error copying from client to backend: {}", e);
-            }
+            io::copy(&mut client_reader, &mut server_writer)
+                .await.expect("Error copying from client to backend");
         });
 
         // Forward from backend to client
         tokio::spawn(async move {
-            if let Err(e) = io::copy(&mut backend_reader, &mut client_writer).await {
-                eprintln!("Error copying from backend to client: {}", e);
-            }
+            io::copy(&mut server_reader, &mut client_writer)
+                .await.expect("Error copying from backend to client");
         });
     } else {
         eprintln!("Failed to connect to the backend server");
     }
+    println!("Connection Closed");
 }

src/mc_types.rs

@@ -0,0 +1,130 @@
+// Yeahbut December 2023
+
+use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use serde::Serialize;
+
+pub const VERSION_NAME: &str = "1.19.4";
+pub const VERSION_PROTOCOL: i32 = 762;
+
+const SEGMENT_BITS: u8 = 0x7F;
+const CONTINUE_BIT: u8 = 0x80;
+
+#[derive(Serialize)]
+pub struct Chat {
+    pub text: String,
+}
+
+pub async fn read_var_int(stream: &mut OwnedReadHalf) -> i32 {
+    let mut value: i32 = 0;
+    let mut position: u32 = 0;
+
+    loop {
+        let current_byte = stream.read_u8()
+            .await
+            .expect("Error reading from stream");
+        value |= ((current_byte & SEGMENT_BITS) as i32) << position;
+
+        if (current_byte & CONTINUE_BIT) == 0 {
+            break;
+        }
+
+        position += 7;
+
+        if position >= 32 {
+            eprintln!("VarInt is too big");
+        }
+    }
+
+    value
+}
+
+pub async fn write_var_int(stream: &mut OwnedWriteHalf, mut value: i32) {
+    loop {
+        if (value & !(SEGMENT_BITS as i32)) == 0 {
+            stream.write_u8(value as u8)
+                .await.expect("Error writing to stream");
+            return;
+        }
+
+        stream.write_u8((value & (SEGMENT_BITS as i32)) as u8 | CONTINUE_BIT)
+            .await
+            .expect("Error writing to stream");
+
+        value >>= 7;
+    }
+}
+
+pub fn write_var_int_bytes(stream: &mut Vec<u8>, mut value: i32) {
+    loop {
+        if (value & !(SEGMENT_BITS as i32)) == 0 {
+            stream.append(&mut vec![value as u8]);
+            return;
+        }
+        stream.append(
+            &mut vec![(value & (SEGMENT_BITS as i32)) as u8 | CONTINUE_BIT]);
+        value >>= 7;
+    }
+}
+
+pub async fn read_var_long(stream: &mut OwnedReadHalf) -> i64 {
+    let mut value: i64 = 0;
+    let mut position: u32 = 0;
+
+    loop {
+        let current_byte = stream.read_u8()
+            .await
+            .expect("Error reading from stream");
+        value |= ((current_byte & SEGMENT_BITS) as i64) << position;
+
+        if (current_byte & CONTINUE_BIT) == 0 {
+            break;
+        }
+
+        position += 7;
+
+        if position >= 64 {
+            eprintln!("VarLong is too big");
+        }
+    }
+
+    value
+}
+
+pub async fn write_var_long(stream: &mut OwnedWriteHalf, mut value: i64) {
+    loop {
+        if (value & !(SEGMENT_BITS as i64)) == 0 {
+            stream.write_u8(value as u8)
+                .await
+                .expect("Error writing to stream");
+            return;
+        }
+
+        stream.write_u8((value & SEGMENT_BITS as i64) as u8 | CONTINUE_BIT)
+            .await
+            .expect("Error writing to stream");
+
+        value >>= 7;
+    }
+}
+
+pub async fn read_string(stream: &mut OwnedReadHalf) -> String {
+    let length = read_var_int(stream).await;
+    let mut buffer = vec![0; length as usize];
+    stream.read_exact(&mut buffer)
+        .await.expect("Error reading string from stream");
+    String::from_utf8_lossy(&buffer).to_string()
+}
+
+pub async fn write_string(stream: &mut OwnedWriteHalf, s: &str) {
+    let length = s.len() as i32;
+    write_var_int(stream, length).await;
+    stream.write_all(s.as_bytes())
+        .await.expect("Error writing string to stream");
+}
+
+pub fn write_string_bytes(stream: &mut Vec<u8>, s: &str) {
+    let length = s.len() as i32;
+    write_var_int_bytes(stream, length);
+    stream.append(&mut s.as_bytes().to_vec());
+}

src/status.rs

@@ -0,0 +1,181 @@
+// Yeahbut December 2023
+
+use std::str::Bytes;
+
+use tokio::net::tcp::{OwnedReadHalf, OwnedWriteHalf};
+use tokio::io::{AsyncReadExt, AsyncWriteExt};
+use serde::Serialize;
+
+use crate::mc_types;
+use crate::handshake;
+
+#[derive(Serialize)]
+pub struct StatusVersion {
+    pub name: String,
+    pub protocol: i32,
+}
+
+#[derive(Serialize)]
+pub struct StatusPlayerInfo {
+    pub name: String,
+    pub id: String,
+}
+
+#[derive(Serialize)]
+pub struct StatusPlayers {
+    pub max: i32,
+    pub online: i32,
+    pub sample: Vec<StatusPlayerInfo>
+}
+
+#[derive(Serialize)]
+pub struct StatusResponse {
+    pub version: StatusVersion,
+    pub description: mc_types::Chat,
+    pub players: StatusPlayers,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub favicon: Option<String>,
+    pub enforcesSecureChat: bool,
+    pub previewsChat: bool,
+}
+
+async fn online_players(
+    server_reader: &mut OwnedReadHalf,
+    server_writer: &mut OwnedWriteHalf,
+) -> StatusPlayers {
+    get_upstream_status(server_reader, server_writer).await.players
+}
+
+fn motd() -> String {
+    "A Minecraft Server Proxy".to_string()
+}
+
+fn favicon() -> Option<String> {
+    None
+}
+
+pub async fn respond_status(
+    client_reader: &mut OwnedReadHalf,
+    client_writer: &mut OwnedWriteHalf,
+    server_reader: &mut OwnedReadHalf,
+    server_writer: &mut OwnedWriteHalf,
+) {
+    loop {
+        let packet_id = client_reader.read_u8()
+            .await.expect("Error reading from stream");
+
+        let online_players = online_players(server_reader, server_writer).await;
+        println!("Status Packet ID: {}", packet_id);
+
+        if packet_id == 0x00 {
+            println!("Handling Status");
+            let status_response = StatusResponse {
+                version: StatusVersion {
+                    name: mc_types::VERSION_NAME.to_string(),
+                    protocol: mc_types::VERSION_PROTOCOL,
+                },
+                description: mc_types::Chat {
+                    text: motd(),
+                },
+                players: StatusPlayers {
+                    max: -13,
+                    online: online_players.online,
+                    sample: online_players.sample,
+                },
+                favicon: favicon(),
+                enforcesSecureChat: false,
+                previewsChat: false,
+            };
+
+            let json_result = serde_json::to_string(&status_response);
+
+            match json_result {
+                Ok(json) => {
+                    client_writer.write_u8(0)
+                        .await.expect("Error writing to stream");
+                    mc_types::write_string(client_writer, &json).await;
+                },
+                Err(err) => {
+                    eprintln!("Error serializing to JSON: {}", err);
+                    break;
+                },
+            }
+        } else if packet_id == 0x01 {
+            println!("Handling Ping");
+            let payload = client_reader.read_i64()
+                .await.expect("Error reading from stream");
+            client_writer.write_u8(0)
+                .await.expect("Error writing to stream");
+            client_writer.write_i64(payload)
+                .await.expect("Error writing to stream");
+            break;
+        } else {
+            break;
+        }
+    }
+}
+
+pub async fn get_upstream_status(
+    server_reader: &mut OwnedReadHalf,
+    server_writer: &mut OwnedWriteHalf,
+) -> StatusResponse {
+    StatusResponse {
+        version: StatusVersion {
+            name: "1.19.4".to_string(),
+            protocol: 762,
+        },
+        description: mc_types::Chat {
+            text: motd(),
+        },
+        players: StatusPlayers {
+            max: 0,
+            online: 0,
+            sample: vec![],
+        },
+        favicon: favicon(),
+        enforcesSecureChat: false,
+        previewsChat: false,
+    }
+}
+
+pub async fn respond_legacy_status(client_writer: &mut OwnedWriteHalf) {
+    println!("Old Style Status");
+    client_writer.write_u8(0xFF)
+        .await.expect("Error writing to stream");
+
+    // let s = "§1\0127\01.12.2\0YTD Proxy§0§10";
+    // println!("String length: {}", s.len());
+    // client_writer.write_u16(s.len() as u16)
+    //     .await.expect("Error writing to stream");
+    // let utf16_bytes: Vec<u16> = s.encode_utf16().collect();
+    // for utf16_char in utf16_bytes {
+    //     client_writer.write_u16(utf16_char)
+    //         .await.expect("Error writing to stream");
+    // }
+
+    let s = "§1\0127\0".to_string() +
+        mc_types::VERSION_NAME +
+        "\0YTD Proxy§0§10";
+    let utf16_vec: Vec<u16> = s
+        .encode_utf16()
+        .flat_map(|c| std::iter::once(c).chain(std::iter::once(0)))
+        .collect();
+    println!("String length: {}", (utf16_vec.len() / 2));
+    client_writer.write_u16((utf16_vec.len() / 2) as u16)
+        .await.expect("Error writing to stream");
+    for utf16_char in utf16_vec {
+        client_writer.write_u16(utf16_char)
+            .await.expect("Error writing to stream");
+    }
+
+    // let s = b"\x00\xa7\x001\x00\x00\x001\x002\x007\x00\x00\x001\x00.\x001\x0
+    //    02\x00.\x002\x00\x00\x00Y\x00T\x00D\x00 \x00P\x00r\x00o\x00x\x00y\x00
+    //    \xa7\x000\xa7\x001\x000";
+    // println!("String length: {}", s.len());
+    // client_writer.write_u16(25)
+    //     .await.expect("Error writing to stream");
+    // for b in s {
+    //     client_writer.write_u8(b)
+    //         .await.expect("Error writing to stream");
+    // }
+}