Added login start packet UUID parsing

An issue has been detected for clients version 1.19.*

Author: Andcool-Systems

Cargo.toml

@@ -23,3 +23,4 @@ tracing = "0.1.41"
 tracing-subscriber = "0.3.19"
 base64_light = "0.1.5"
 toml = "0.8.20"
+uuid = "1.13.1"

README.md

@@ -118,5 +118,8 @@ bad_session = "§cFailed to login: Invalid session (Try restarting your game and
 ### 🚀 Running
 After configuring, run the compiled binary file through the console.
 
+## Known issues
+- For Minecraft 1.19.* clients, encryption does not work correctly
+
 ---
 **Created by AndcoolSystems with ❤, 3 February, 2025**

config.toml

@@ -6,7 +6,7 @@ code_life_time = 300
 [server]
 addr = "0.0.0.0"
 port = 25566
-timeout = 10
+timeout = 20
 
 [server.config]
 protocol = 0

src/byte_buf_utils.rs

@@ -1,5 +1,7 @@
+use anyhow::Error;
 use bytes::{Buf, BufMut, BytesMut};
 use std::io::{self, ErrorKind};
+use uuid::Uuid;
 
 pub fn read_utf8(buf: &mut BytesMut) -> io::Result<String> {
     let len = read_varint(buf)?;
@@ -76,3 +78,18 @@ pub fn read_unsigned_short(buf: &mut BytesMut) -> io::Result<u16> {
     }
     Ok(buf.get_u16())
 }
+
+pub fn try_get_uuid(buf: &mut BytesMut) -> anyhow::Result<Uuid> {
+    let len = buf.len();
+    if len < 16 {
+        return Err(Error::msg("Not enough data"));
+    }
+
+    if len > 16 {
+        buf.advance(len - 16); // Normalize uuid length
+    }
+
+    let mut bytes = [0u8; 16];
+    buf.copy_to_slice(&mut bytes);
+    Ok(uuid::Uuid::from_slice(&bytes)?)
+}

src/client_sessions.rs

@@ -1,10 +1,6 @@
-// use std::collections::HashMap;
-// use std::net::SocketAddr;
-// use std::sync::Arc;
-// use tokio::sync::Mutex;
-
 use aes::Aes128;
 use cfb8::Encryptor;
+use uuid::Uuid;
 
 use crate::generators::keys::generate_verify_token;
 
@@ -21,6 +17,7 @@ pub struct Session {
     pub proto_ver: Option<usize>,
     pub next_state: NextStateEnum,
     pub nickname: Option<String>,
+    pub uuid: Option<Uuid>,
     pub secret: Option<Vec<u8>>, // Shared secret,
     pub verify_token: [u8; 4],
     pub cipher: Option<Encryptor<Aes128>>,
@@ -33,11 +30,10 @@ impl Session {
             proto_ver: None,
             next_state: NextStateEnum::Unknown,
             nickname: None,
+            uuid: None,
             secret: None,
             verify_token: generate_verify_token(),
             cipher: None,
         }
     }
 }
-
-//pub type SessionMap = Arc<Mutex<HashMap<SocketAddr, Session>>>;

src/handlers/client_handler.rs

@@ -55,7 +55,8 @@ pub async fn handle(mut stream: TcpStream, keys: Arc<rsa::RsaPrivateKey>) -> Res
                             }
                             NextStateEnum::Login => {
                                 debug!("Received encryption response");
-                                encryption_response::handle(session, &mut buffer, keys.clone())?;
+                                encryption_response::handle(session, &mut buffer, keys.clone())
+                                    .expect("Encryption response handling error");
 
                                 let player_data = mojang::join(session, keys.clone()).await?;
                                 if player_data.is_none() {

src/handlers/login_start.rs

@@ -1,9 +1,9 @@
 use crate::{client_sessions::Session, packets::login_start::LoginStartPacket};
 use bytes::BytesMut;
-use tokio::io;
 
-pub fn handle(session: &mut Session, buff: &mut BytesMut) -> Result<(), io::Error> {
+pub fn handle(session: &mut Session, buff: &mut BytesMut) -> anyhow::Result<()> {
     let packet = LoginStartPacket::parse(buff)?;
     session.nickname = Some(packet.name);
+    session.uuid = packet.uuid;
     Ok(())
 }

src/mojang/mod.rs

@@ -4,6 +4,7 @@ use std::sync::Arc;
 
 use anyhow::Result;
 use sha1::{Digest, Sha1};
+use tracing::debug;
 
 use crate::{client_sessions::Session, config};
 use rsa::pkcs8::EncodePublicKey;
@@ -20,6 +21,8 @@ pub async fn join(
     digest.update(keys.to_public_key().to_public_key_der()?.as_bytes());
     let hash = BigInt::from_signed_bytes_be(&digest.finalize()).to_str_radix(16);
 
+    debug!("Creating request to Mojang API with hash: {hash}");
+
     let config = config::get_config().await;
     let response = reqwest::get(
         config
@@ -31,6 +34,11 @@ pub async fn join(
     )
     .await?;
 
+    debug!(
+        "Mojang API responded with code: {}",
+        response.status().as_u16()
+    );
+
     if response.status().as_u16() != 200 {
         return Ok(None);
     }

src/packets/login_start.rs

@@ -1,19 +1,22 @@
 use bytes::BytesMut;
-use tokio::io;
+use uuid::Uuid;
 
-use crate::byte_buf_utils::read_utf8;
+use crate::byte_buf_utils::{read_utf8, try_get_uuid};
 
 #[allow(dead_code)]
 pub struct LoginStartPacket {
     pub name: String,
-    pub uuid: String,
+    pub uuid: Option<Uuid>,
 }
 
 impl LoginStartPacket {
-    pub fn parse(buff: &mut BytesMut) -> Result<Self, io::Error> {
+    pub fn parse(buff: &mut BytesMut) -> anyhow::Result<Self> {
         Ok(Self {
             name: read_utf8(buff)?,
-            uuid: "".to_string(),
+            uuid: match try_get_uuid(buff) {
+                Ok(uuid) => Some(uuid),
+                Err(_) => None,
+            },
         })
     }
 }