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Copy pathinitial_handler.rs
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327 lines (281 loc) · 9.83 KB
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//! Initial handling of a connection.
use crate::{connection_worker::Worker, favicon::Favicon};
use anyhow::bail;
use base::{ProfileProperty, Text};
use flume::{Receiver, Sender};
use md5::Digest;
use num_bigint::BigInt;
use once_cell::sync::Lazy;
use protocol::{
codec::CryptKey,
packets::{
client::{HandshakeState, Ping},
server::{
DisconnectLogin, EncryptionRequest, LoginSuccess, Pong, Response, SetCompression,
},
},
ClientHandshakePacket, ClientLoginPacket, ClientPlayPacket, ClientStatusPacket,
ServerLoginPacket, ServerPlayPacket, ServerStatusPacket,
};
use rand::rngs::OsRng;
use rsa::{PaddingScheme, PublicKeyParts, RsaPrivateKey};
use serde::{Deserialize, Serialize};
use sha1::Sha1;
use std::convert::TryInto;
use uuid::Uuid;
use self::proxy::ProxyData;
const SERVER_NAME: &str = "Feather 1.16.5";
const PROTOCOL_VERSION: i32 = 754;
mod proxy;
/// Information for a newly connected player.
#[derive(Debug)]
pub struct NewPlayer {
pub uuid: Uuid,
pub username: String,
pub profile: Vec<ProfileProperty>,
pub received_packets: Receiver<ClientPlayPacket>,
pub packets_to_send: Sender<ServerPlayPacket>,
}
/// Result of initial handling.
pub enum InitialHandling {
/// The client should be disconnected (sent when
/// the connection was just a "status" ping.)
Disconnect,
/// We should create a new player.
Join(NewPlayer),
}
/// Handles a connection until the protocol state is switched to Play;
/// that is, until we send Login Success. Returns the client's information.
pub async fn handle(worker: &mut Worker) -> anyhow::Result<InitialHandling> {
// Get the handshake packet.
let handshake = worker.read::<ClientHandshakePacket>().await?;
let ClientHandshakePacket::Handshake(handshake) = handshake;
match handshake.next_state {
HandshakeState::Status => handle_status(worker).await,
HandshakeState::Login => {
if handshake.protocol_version < PROTOCOL_VERSION {
worker
.write(ServerLoginPacket::DisconnectLogin(DisconnectLogin {
reason: Text::from(
"Invalid protocol! The server is running on version 1.16!",
)
.to_string(),
}))
.await
.ok();
return Ok(InitialHandling::Disconnect);
}
let proxy_data =
if let Some(crate::options::ProxyMode::Bungeecord) = worker.options().proxy_mode {
Some(proxy::do_bungee_ip_forwarding(&handshake)?)
} else {
None
};
handle_login(worker, proxy_data).await
}
}
}
#[derive(Debug, Serialize)]
struct StatusResponse<'a> {
version: Version,
players: Players,
description: Text,
#[serde(skip_serializing_if = "Option::is_none")]
favicon: Option<&'a str>,
}
#[derive(Debug, Serialize)]
struct Version {
name: &'static str,
protocol: i32,
}
#[derive(Debug, Serialize)]
struct Players {
max: u32,
online: u32,
}
async fn handle_status(worker: &mut Worker) -> anyhow::Result<InitialHandling> {
let _request = worker.read::<ClientStatusPacket>().await?;
let payload = StatusResponse {
version: Version {
name: SERVER_NAME,
protocol: PROTOCOL_VERSION,
},
players: Players {
max: worker.options().max_players,
online: worker.player_count(),
},
description: Text::from(worker.options().motd.clone()),
favicon: worker
.options()
.favicon
.as_ref()
.map(Favicon::base64_encoded),
};
let response = Response {
response: serde_json::to_string(&payload)?,
};
worker
.write(&ServerStatusPacket::Response(response))
.await?;
match worker.read::<Ping>().await {
Ok(ping) => {
let pong = Pong {
payload: ping.payload,
};
worker.write(&ServerStatusPacket::Pong(pong)).await?;
}
Err(e) => {
log::debug!("Didn't receive ping packet from status call: {}", e);
}
}
Ok(InitialHandling::Disconnect)
}
async fn handle_login(
worker: &mut Worker,
mut proxy_data: Option<ProxyData>,
) -> anyhow::Result<InitialHandling> {
let login_start = match worker.read::<ClientLoginPacket>().await? {
ClientLoginPacket::LoginStart(l) => l,
_ => bail!("expected login start"),
};
log::debug!("{} is logging in", login_start.name);
// Velocity IP forwarding runs after Login Start is received.
if let Some(crate::options::ProxyMode::Velocity) = worker.options().proxy_mode {
proxy_data = Some(proxy::do_velocity_ip_forwarding(worker).await?);
}
if worker.options().online_mode {
enable_encryption(worker, login_start.name).await
} else {
let profile = match proxy_data {
Some(proxy_data) => AuthResponse {
id: proxy_data.uuid,
name: login_start.name.clone(),
properties: proxy_data.profile,
},
None => offline_mode_profile(login_start.name),
};
finish_login(worker, profile).await
}
}
fn offline_mode_profile(username: String) -> AuthResponse {
// TODO: correct offline mode handling
AuthResponse {
id: offline_mode_uuid(&username),
name: username,
properties: Vec::new(),
}
}
fn offline_mode_uuid(username: &str) -> Uuid {
// See: https://gist.github.com/games647/2b6a00a8fc21fd3b88375f03c9e2e603
let mut hasher = md5::Md5::default();
hasher.update(format!("OfflinePlayer:{}", username).as_bytes());
let hash = hasher.finalize();
let mut builder = uuid::Builder::from_bytes(hash.try_into().unwrap());
builder
.set_variant(uuid::Variant::RFC4122)
.set_version(uuid::Version::Md5);
builder.build()
}
const RSA_BITS: usize = 1024;
/// Cached RSA key used by this server instance.
static RSA_KEY: Lazy<RsaPrivateKey> =
Lazy::new(|| RsaPrivateKey::new(&mut OsRng, RSA_BITS).expect("failed to create RSA key"));
static RSA_KEY_ENCODED: Lazy<Vec<u8>> = Lazy::new(|| {
rsa_der::public_key_to_der(&RSA_KEY.n().to_bytes_be(), &RSA_KEY.e().to_bytes_be())
});
async fn enable_encryption(
worker: &mut Worker,
username: String,
) -> anyhow::Result<InitialHandling> {
log::debug!("Authenticating {}", username);
let shared_secret = do_encryption_handshake(worker).await?;
worker.enable_encryption(shared_secret);
let response = authenticate(shared_secret, username).await?;
finish_login(worker, response).await
}
async fn do_encryption_handshake(worker: &mut Worker) -> anyhow::Result<CryptKey> {
let verify_token: [u8; 16] = rand::random();
let request = EncryptionRequest {
server_id: String::new(), // always empty
public_key: RSA_KEY_ENCODED.clone(),
verify_token: verify_token.to_vec(),
};
worker
.write(&ServerLoginPacket::EncryptionRequest(request))
.await?;
let response = match worker.read::<ClientLoginPacket>().await? {
ClientLoginPacket::EncryptionResponse(r) => r,
_ => bail!("expected encryption response"),
};
// Decrypt shared secret and verify token.
let shared_secret = RSA_KEY.decrypt(PaddingScheme::PKCS1v15Encrypt, &response.shared_secret)?;
let received_verify_token =
RSA_KEY.decrypt(PaddingScheme::PKCS1v15Encrypt, &response.verify_token)?;
if received_verify_token != verify_token {
bail!("verify tokens do not match");
}
Ok((&shared_secret[..]).try_into()?)
}
#[derive(Debug, Deserialize)]
struct AuthResponse {
id: Uuid,
name: String,
properties: Vec<ProfileProperty>,
}
async fn authenticate(shared_secret: CryptKey, username: String) -> anyhow::Result<AuthResponse> {
let server_hash = compute_server_hash(shared_secret);
let response: AuthResponse = tokio::task::spawn_blocking(move || {
let url = format!(
"https://sessionserver.mojang.com/session/minecraft/hasJoined?username={}&serverId={}",
username, server_hash
);
let response = ureq::get(&url).call()?;
Result::<AuthResponse, anyhow::Error>::Ok(response.into_json()?)
})
.await??;
Ok(response)
}
fn compute_server_hash(shared_secret: CryptKey) -> String {
let mut hasher = Sha1::new();
hasher.update(b""); // server ID - always empty
hasher.update(&shared_secret);
hasher.update(&*RSA_KEY_ENCODED);
hexdigest(hasher.finalize().as_slice())
}
// Non-standard hex digest used by Minecraft.
fn hexdigest(bytes: &[u8]) -> String {
let bigint = BigInt::from_signed_bytes_be(bytes);
format!("{:x}", bigint)
}
async fn finish_login(
worker: &mut Worker,
response: AuthResponse,
) -> anyhow::Result<InitialHandling> {
enable_compression(worker).await?;
let success = LoginSuccess {
uuid: response.id,
username: response.name.clone(),
};
worker
.write(&ServerLoginPacket::LoginSuccess(success))
.await?;
let new_player = NewPlayer {
username: response.name,
uuid: response.id,
profile: response.properties,
received_packets: worker.received_packets(),
packets_to_send: worker.packets_to_send(),
};
log::debug!("Completed initial handling for {}", new_player.username);
Ok(InitialHandling::Join(new_player))
}
async fn enable_compression(worker: &mut Worker) -> anyhow::Result<()> {
if let Some(threshold) = worker.options().compression_threshold {
let packet = ServerLoginPacket::SetCompression(SetCompression {
threshold: threshold as i32,
});
worker.write(&packet).await?;
worker.enable_compression(threshold);
}
Ok(())
}
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