Handshake with forge server, error handling

Cargo.lock

@@ -3,19 +3,19 @@
 version = 4
 
 [[package]]
-name = "client"
+name = "itoa"
+version = "1.0.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
+
+[[package]]
+name = "mc_chat_client"
 version = "0.1.0"
 dependencies = [
  "serde_json",
  "varint-rs",
 ]
 
-[[package]]
-name = "itoa"
-version = "1.0.15"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
-
 [[package]]
 name = "memchr"
 version = "2.7.4"

Cargo.toml

@@ -1,5 +1,5 @@
 [package]
-name = "client"
+name = "mc_chat_client"
 version = "0.1.0"
 edition = "2024"
 

src/connect.rs

@@ -0,0 +1,246 @@
+use std::{
+    collections::HashMap,
+    io::{Read, Write},
+};
+
+use varint_rs::{VarintReader, VarintWriter};
+
+use crate::{
+    Connected, Server, Status,
+    error::ChatError,
+    error::Result,
+    readers::{read_packet, read_plugin_msg, read_string},
+    status::ServerType,
+    writers::{write_packet, write_plugin_msg, write_string},
+};
+
+impl Server<Status> {
+    pub fn connect(self) -> Result<Server<Connected>> {
+        let Self {
+            mut stream,
+            addr,
+            port,
+            state:
+                Status {
+                    typ,
+                    description,
+                    mods,
+                },
+        } = self;
+
+        let (uuid, username) = match typ {
+            ServerType::Vanilla => {
+                // Handshake
+                write_packet(&mut stream, |buf| {
+                    buf.write_u8_varint(0)?;
+                    buf.write_u8_varint(5)?;
+                    buf.write_usize_varint(addr.len())?;
+                    buf.write_all(addr.as_bytes())?;
+                    buf.write_all(&port.to_le_bytes())?;
+                    buf.write_u8_varint(2)?;
+                    Ok(())
+                })?;
+
+                // Login start
+                write_packet(&mut stream, |buf| {
+                    buf.write_u8_varint(0)?;
+                    let uname = "McChatClient";
+                    write_string(buf, uname)?;
+                    Ok(())
+                })?;
+
+                read_packet(&mut stream, |packet| {
+                    let id = packet.read_usize_varint()?;
+                    assert!(id == 2);
+                    let uuid = read_string(packet)?;
+                    let username = read_string(packet)?;
+                    Ok((uuid, username))
+                })?
+            }
+            ServerType::Forge => {
+                // Handshake
+
+                write_packet(&mut stream, |buf| {
+                    buf.write_u8_varint(0)?;
+                    buf.write_u8_varint(5)?;
+                    let addr = format!("{addr}\0FML\0");
+                    buf.write_usize_varint(addr.len())?;
+                    buf.write_all(addr.as_bytes())?;
+                    buf.write_all(&port.to_le_bytes())?;
+                    buf.write_u8_varint(2)?;
+                    Ok(())
+                })?;
+
+                // Login start
+                write_packet(&mut stream, |buf| {
+                    buf.write_u8_varint(0)?;
+                    let uname = "McChatClient";
+                    write_string(buf, uname)?;
+                    Ok(())
+                })?;
+
+                // Login Success
+                let (uuid, username) = read_packet(&mut stream, |packet| {
+                    let id = packet.read_usize_varint()?;
+                    assert!(id == 2);
+                    let uuid = read_string(packet)?;
+                    let username = read_string(packet)?;
+                    Ok((uuid, username))
+                })?;
+
+                // Server Register Channels
+                let (_channels, channels_buf) =
+                    read_plugin_msg(&mut stream, "REGISTER", |packet| {
+                        Ok((
+                            packet
+                                .split(|b| *b == 0)
+                                .map(|b| String::from_utf8(b.to_vec()).map_err(ChatError::from))
+                                .collect::<Result<Vec<_>>>()?,
+                            packet.to_vec(),
+                        ))
+                    })?;
+
+                // Server Hello
+                let _dim = read_plugin_msg(&mut stream, "FML|HS", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 0);
+                    let proto_ver = VarintReader::read(packet)?;
+                    assert_eq!(proto_ver, 2);
+                    let mut buf = [0u8; 4];
+                    packet.read_exact(&mut buf)?;
+                    let dim = i32::from_be_bytes(buf);
+                    Ok(dim)
+                })?;
+
+                // Client Register Channels
+                write_plugin_msg(&mut stream, "REGISTER", |body| {
+                    body.write_all(&channels_buf)?;
+                    Ok(())
+                })?;
+
+                // Client Hello
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0x1])?;
+                    body.write_all(&[0x2])?;
+                    Ok(())
+                })?;
+
+                // Client Modlist
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0x2])?;
+                    let mods = mods.as_ref().unwrap();
+                    body.write_usize_varint(mods.len())?;
+
+                    for (id, ver) in mods {
+                        write_string(body, id)?;
+                        write_string(body, ver)?;
+                    }
+                    Ok(())
+                })?;
+
+                // Server Modlist
+                let _mods = read_plugin_msg(&mut stream, "FML|HS", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 2);
+                    let num_mods = VarintReader::read(packet)?;
+
+                    let mut mods = HashMap::new();
+                    for _ in 0..num_mods {
+                        let id = read_string(packet)?;
+                        let ver = read_string(packet)?;
+                        mods.insert(id, ver);
+                    }
+                    Ok(mods)
+                })?;
+
+                // HandshakeAck waitingseverdata
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0xFF, 0x02])?;
+                    Ok(())
+                })?;
+
+                // Server RegistryData
+                read_plugin_msg(&mut stream, "FML|HS", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 3);
+                    let num_ids = packet.read_usize_varint()?;
+
+                    for _ in 0..num_ids {
+                        let _name = read_string(packet)?;
+                        let _id = packet.read_usize_varint()?;
+                    }
+
+                    if packet.len() > 0 {
+                        let len = packet.read_usize_varint()?;
+                        for _ in 0..len {
+                            read_string(packet)?;
+                        }
+
+                        let len = packet.read_usize_varint()?;
+                        for _ in 0..len {
+                            read_string(packet)?;
+                        }
+                    }
+                    Ok(())
+                })?;
+
+                // Server HandshakeAck waitingack
+                read_plugin_msg(&mut stream, "FML|HS", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 255);
+                    let phrase = VarintReader::read(packet)?;
+                    assert_eq!(phrase, 2);
+                    Ok(())
+                })?;
+
+                // HandshakeAck waitingsevercomplete
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0xFF, 0x03])?;
+                    Ok(())
+                })?;
+
+                // Serrver FluidIdmap
+                read_plugin_msg(&mut stream, "FORGE", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 2);
+                    Ok(())
+                })?;
+
+                // HandshakeAck pendingcomplete
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0xFF, 0x04])?;
+                    Ok(())
+                })?;
+
+                // Server HandshakeAck complete
+                read_plugin_msg(&mut stream, "FML|HS", |packet| {
+                    let discriminant = VarintReader::read(packet)?;
+                    assert_eq!(discriminant, 255);
+                    let phrase = VarintReader::read(packet)?;
+                    assert_eq!(phrase, 3);
+                    Ok(())
+                })?;
+
+                // HandshakeAck complete
+                write_plugin_msg(&mut stream, "FML|HS", |body| {
+                    body.write_all(&[0xFF, 0x05])?;
+                    Ok(())
+                })?;
+
+                (uuid, username)
+            }
+        };
+
+        Ok(Server {
+            stream,
+            addr,
+            port,
+            state: Connected {
+                typ,
+                description,
+                uuid,
+                username,
+            },
+        })
+    }
+}

src/error.rs

@@ -0,0 +1,44 @@
+use serde_json::Value;
+use std::{io, result::Result as StdResult, string::FromUtf8Error};
+
+#[derive(Debug)]
+pub enum ChatError {
+    IoError(io::Error),
+    FromUtf8Error(FromUtf8Error),
+    JsonError(JsonError),
+}
+
+#[derive(Debug)]
+pub enum JsonError {
+    SerdeError(serde_json::Error),
+    ExpectedObject(Value),
+    ExpectedArray,
+    ExpectedString,
+    ExpectedMember(String),
+}
+
+impl From<io::Error> for ChatError {
+    fn from(value: io::Error) -> Self {
+        Self::IoError(value)
+    }
+}
+
+impl From<FromUtf8Error> for ChatError {
+    fn from(value: FromUtf8Error) -> Self {
+        Self::FromUtf8Error(value)
+    }
+}
+
+impl From<JsonError> for ChatError {
+    fn from(value: JsonError) -> Self {
+        Self::JsonError(value)
+    }
+}
+
+impl From<serde_json::Error> for JsonError {
+    fn from(value: serde_json::Error) -> Self {
+        Self::SerdeError(value)
+    }
+}
+
+pub type Result<T> = StdResult<T, ChatError>;

src/main.rs

@@ -1,63 +1,75 @@
+mod connect;
+mod error;
 mod readers;
+mod status;
 mod text;
+mod writers;
 
 use std::{
+    collections::HashMap,
+    fmt::Debug,
     io::{Read, Write},
     net::TcpStream,
 };
 
-use readers::{read_packet, read_string};
+use error::Result;
+use readers::read_string;
+use status::ServerType;
 use text::Message;
 use varint_rs::{VarintReader, VarintWriter};
 
-fn main() {
-    let mut stream = TcpStream::connect("localhost:25565").unwrap();
+pub trait ServerState {}
 
-    // Handshake
-    let mut buf: Vec<u8> = Vec::new();
-    buf.write_u8_varint(0).unwrap();
-    buf.write_u8_varint(5).unwrap();
-    let addr = "localhost";
-    buf.write_usize_varint(addr.len()).unwrap();
-    buf.write_all(addr.as_bytes()).unwrap();
-    buf.write_all(&25565u16.to_le_bytes()).unwrap();
-    buf.write_u8_varint(2).unwrap();
+#[derive(Debug)]
+pub struct Disconnected;
+impl ServerState for Disconnected {}
+#[derive(Debug)]
+pub struct Status {
+    typ: ServerType,
+    description: String,
+    mods: Option<HashMap<String, String>>,
+}
+impl ServerState for Status {}
+#[derive(Debug)]
+#[allow(unused)]
+pub struct Connected {
+    typ: ServerType,
+    description: String,
+    uuid: String,
+    username: String,
+}
+impl ServerState for Connected {}
 
-    stream.write_usize_varint(buf.len()).unwrap();
-    stream.write_all(&buf).unwrap();
+#[derive(Debug)]
+pub struct Server<S: ServerState + Debug> {
+    stream: TcpStream,
+    addr: String,
+    port: u16,
+    state: S,
+}
 
-    // Login start
-    let mut buf: Vec<u8> = Vec::new();
-    buf.write_u8_varint(0).unwrap();
-    let addr = "CursedChat";
-    buf.write_usize_varint(addr.len()).unwrap();
-    buf.write_all(addr.as_bytes()).unwrap();
+impl Server<Disconnected> {
+    fn new(addr: String, port: u16) -> Result<Self> {
+        Ok(Self {
+            stream: TcpStream::connect(format!("{addr}:{port}"))?,
+            addr,
+            port,
+            state: Disconnected,
+        })
+    }
+}
 
-    stream.write_usize_varint(buf.len()).unwrap();
-    stream.write_all(&buf).unwrap();
+fn main() -> Result<()> {
+    let server = Server::new("localhost".to_string(), 25565)?;
+    dbg!(&server);
 
-    let mut buf = [0u8; 128];
-    dbg!(Read::read(&mut stream, &mut buf).unwrap());
-    println!("{:X?}", buf);
+    let server = server.status()?;
+    dbg!(&server);
 
-    let mut iter = buf.into_iter();
-    let _len = iter.next().unwrap();
-    let id = iter.next().unwrap();
-    assert!(id == 2);
-    let uuid = read_string(&mut iter);
-    let username = read_string(&mut iter);
-    dbg!(uuid, username);
+    let server = server.connect()?;
+    dbg!(&server);
 
-    loop {
-        let packet = read_packet(&mut stream);
-        let packetid = (&packet[..]).read_usize_varint().unwrap();
-        match packetid {
-            0x00 => handle_keepalive(&mut stream, &packet),
-            0x02 => handle_chat(&packet),
-            0x40 => break,
-            _ => {}
-        }
-    }
+    Ok(())
 }
 
 fn handle_keepalive(stream: &mut TcpStream, mut packet: &[u8]) {
@@ -76,8 +88,7 @@ fn handle_keepalive(stream: &mut TcpStream, mut packet: &[u8]) {
 fn handle_chat(mut packet: &[u8]) {
     let _packetid = packet.read_usize_varint().unwrap();
 
-    let mut iter = packet.iter().cloned();
-    let msg = read_string(&mut iter);
+    let msg = read_string(&mut packet);
     let msg = Message::from_string(msg.unwrap());
     dbg!(msg);
 }

src/readers.rs

@@ -1,19 +1,47 @@
-use std::{io::Read as _, net::TcpStream};
+use std::{io::Read, net::TcpStream};
+
+use crate::error::Result;
 
 use varint_rs::VarintReader as _;
 
-pub fn read_string<I: Iterator<Item = u8>>(iter: &mut I) -> Option<String> {
-    let len = iter.next()?.into();
-    let bytes = iter.take(len).collect::<Vec<_>>();
-    (len == bytes.len()).then_some(())?;
-    String::from_utf8(bytes).ok()
+pub fn read_string(iter: &mut &[u8]) -> Result<String> {
+    let len = iter.read_usize_varint()?;
+    let mut buf = vec![0u8; len];
+    iter.read_exact(&mut buf)?;
+    String::from_utf8(buf).map_err(Into::into)
 }
 
-pub fn read_packet(stream: &mut TcpStream) -> Vec<u8> {
-    let len = stream.read_usize_varint().unwrap();
+pub fn read_packet<T, F: Fn(&mut &[u8]) -> Result<T>>(
+    stream: &mut TcpStream,
+    read_body: F,
+) -> Result<T> {
+    let len = stream.read_usize_varint()?;
 
     let mut buf = vec![0u8; len];
-    stream.read_exact(&mut buf).unwrap();
+    stream.read_exact(&mut buf)?;
+
+    let mut packet = &buf[..];
+    read_body(&mut packet)
+}
+
+pub fn read_plugin_msg<T, F: Fn(&mut &[u8]) -> Result<T>>(
+    stream: &mut TcpStream,
+    channel: &str,
+    read_body: F,
+) -> Result<T> {
+    read_packet(stream, |packet| {
+        let id = packet.read_usize_varint()?;
+        assert!(id == 63);
+
+        let channel_read = read_string(packet)?;
+        assert_eq!(channel_read, channel);
+        let mut buf = [0u8; 2];
+        packet.read_exact(&mut buf)?;
+        let len = u16::from_be_bytes(buf);
+        let mut buf = vec![0u8; len as usize];
+        packet.read_exact(&mut buf)?;
 
-    buf
+        let mut packet = &buf[..];
+        read_body(&mut packet)
+    })
 }

src/status.rs

@@ -0,0 +1,118 @@
+use std::{collections::HashMap, io::Write, net::TcpStream};
+
+use serde_json::Value;
+use varint_rs::{VarintReader, VarintWriter};
+
+use crate::{
+    Disconnected, Server, Status,
+    error::ChatError,
+    error::JsonError,
+    error::Result,
+    readers::{read_packet, read_string},
+    writers::write_packet,
+};
+
+#[derive(Debug)]
+pub enum ServerType {
+    Vanilla,
+    Forge,
+}
+
+impl Server<Disconnected> {
+    pub fn status(self) -> Result<Server<Status>> {
+        let Self {
+            mut stream,
+            addr,
+            port,
+            ..
+        } = self;
+
+        // Handshake
+
+        write_packet(&mut stream, |buf| {
+            buf.write_u8_varint(0)?;
+            buf.write_u8_varint(5)?;
+            buf.write_usize_varint(addr.len())?;
+            buf.write_all(addr.as_bytes())?;
+            buf.write_all(&port.to_le_bytes())?;
+            buf.write_u8_varint(1)?;
+            Ok(())
+        })?;
+
+        write_packet(&mut stream, |buf| {
+            buf.write_all(&[0x0])?;
+            Ok(())
+        })?;
+
+        let json: Value = read_packet(&mut stream, |packet| {
+            let id = packet.read_usize_varint()?;
+            assert!(id == 0);
+            let json = read_string(packet)?;
+            serde_json::from_str(&json)
+                .map_err(<JsonError as From<serde_json::Error>>::from)
+                .map_err(ChatError::from)
+        })?;
+
+        let json = json
+            .as_object()
+            .ok_or(JsonError::ExpectedObject(json.clone()))?;
+        let description = json
+            .get("description")
+            .ok_or(JsonError::ExpectedMember("description".to_string()))?
+            .as_str()
+            .ok_or(JsonError::ExpectedString)?
+            .to_string();
+
+        let (typ, mods) = match json.get("modinfo") {
+            Some(info) => {
+                if info
+                    .as_object()
+                    .ok_or(JsonError::ExpectedObject(info.clone()))?
+                    .get("type")
+                    .ok_or(JsonError::ExpectedMember("type".to_string()))?
+                    .as_str()
+                    .ok_or(JsonError::ExpectedString)?
+                    == "FML"
+                {
+                    let mod_list = info
+                        .get("modList")
+                        .ok_or(JsonError::ExpectedMember("modList".to_string()))?;
+                    let mod_list = mod_list.as_array().ok_or(JsonError::ExpectedArray)?;
+                    let mut mods = HashMap::new();
+                    for mod_ in mod_list {
+                        let mod_ = mod_
+                            .as_object()
+                            .ok_or(JsonError::ExpectedObject(mod_.clone()))?;
+                        let id = mod_
+                            .get("modid")
+                            .ok_or(JsonError::ExpectedMember("modid".to_string()))?;
+                        let ver = mod_
+                            .get("version")
+                            .ok_or(JsonError::ExpectedMember("version".to_string()))?;
+                        mods.insert(
+                            id.as_str().ok_or(JsonError::ExpectedString)?.to_string(),
+                            ver.as_str().ok_or(JsonError::ExpectedString)?.to_string(),
+                        );
+                    }
+                    (ServerType::Forge, Some(mods))
+                } else {
+                    panic!()
+                }
+            }
+            None => (ServerType::Vanilla, None),
+        };
+
+        stream.shutdown(std::net::Shutdown::Both)?;
+
+        Ok(Server {
+            stream: TcpStream::connect(format!("{addr}:{port}"))?,
+            addr,
+            port,
+            state: Status {
+                typ,
+                description,
+                mods,
+            },
+        })
+    }
+}

src/writers.rs

@@ -0,0 +1,41 @@
+use std::{io::Write, net::TcpStream};
+
+use varint_rs::VarintWriter;
+
+use crate::error::Result;
+
+pub fn write_packet<F: Fn(&mut Vec<u8>) -> Result<()>>(
+    stream: &mut TcpStream,
+    build_packet: F,
+) -> Result<()> {
+    let mut buf: Vec<u8> = Vec::new();
+    build_packet(&mut buf)?;
+
+    stream.write_usize_varint(buf.len())?;
+    stream.write_all(&buf)?;
+
+    Ok(())
+}
+
+pub fn write_string<W: Write>(buf: &mut W, val: &str) -> Result<()> {
+    buf.write_usize_varint(val.len())?;
+    buf.write_all(val.as_bytes())?;
+    Ok(())
+}
+
+pub fn write_plugin_msg<F: Fn(&mut Vec<u8>) -> Result<()>>(
+    stream: &mut TcpStream,
+    channel: &str,
+    build_body: F,
+) -> Result<()> {
+    let mut body: Vec<u8> = Vec::new();
+    build_body(&mut body)?;
+
+    write_packet(stream, |mut buf| {
+        buf.write_u8_varint(0x17)?;
+        write_string(&mut buf, channel)?;
+        buf.write_all(&(body.len() as u16).to_be_bytes())?;
+        buf.write_all(&body)?;
+        Ok(())
+    })
+}