1 files changed, 131 insertions, 0 deletions
diff --git a/mumd/src/network/udp.rs b/mumd/src/network/udp.rs
new file mode 100644
index 0000000..39f16b6
--- /dev/null
+++ b/mumd/src/network/udp.rs
@@ -0,0 +1,131 @@
+use crate::audio::Audio;
+use log::*;
+
+use bytes::Bytes;
+use futures::channel::oneshot;
+use futures::{join, SinkExt, StreamExt};
+use futures_util::stream::{SplitSink, SplitStream};
+use mumble_protocol::crypt::ClientCryptState;
+use mumble_protocol::voice::{VoicePacket, VoicePacketPayload};
+use mumble_protocol::Serverbound;
+use std::net::{Ipv6Addr, SocketAddr};
+use std::sync::{Arc, Mutex};
+use tokio::net::UdpSocket;
+use tokio_util::udp::UdpFramed;
+
+type UdpSender = SplitSink<UdpFramed<ClientCryptState>, (VoicePacket<Serverbound>, SocketAddr)>;
+type UdpReceiver = SplitStream<UdpFramed<ClientCryptState>>;
+
+pub async fn connect(
+    crypt_state: oneshot::Receiver<ClientCryptState>,
+) -> (UdpSender, UdpReceiver) {
+    // Bind UDP socket
+    let udp_socket = UdpSocket::bind((Ipv6Addr::from(0u128), 0u16))
+        .await
+        .expect("Failed to bind UDP socket");
+
+    // Wait for initial CryptState
+    let crypt_state = match crypt_state.await {
+        Ok(crypt_state) => crypt_state,
+        // disconnected before we received the CryptSetup packet, oh well
+        Err(_) => panic!("disconnect before crypt packet received"), //TODO exit gracefully
+    };
+    debug!("UDP connected");
+
+    // Wrap the raw UDP packets in Mumble's crypto and voice codec (CryptState does both)
+    UdpFramed::new(udp_socket, crypt_state).split()
+}
+
+async fn listen(
+    _sink: Arc<Mutex<UdpSender>>,
+    mut source: UdpReceiver,
+    audio: Arc<Mutex<Audio>>,
+) {
+    while let Some(packet) = source.next().await {
+        let (packet, _src_addr) = match packet {
+            Ok(packet) => packet,
+            Err(err) => {
+                warn!("Got an invalid UDP packet: {}", err);
+                // To be expected, considering this is the internet, just ignore it
+                continue;
+            }
+        };
+        match packet {
+            VoicePacket::Ping { .. } => {
+                // Note: A normal application would handle these and only use UDP for voice
+                //       once it has received one.
+                continue;
+            }
+            VoicePacket::Audio {
+                session_id,
+                // seq_num,
+                payload,
+                // position_info,
+                ..
+            } => {
+                audio.lock().unwrap().decode_packet(session_id, payload);
+            }
+        }
+    }
+}
+
+async fn send_ping(sink: &mut UdpSender, server_addr: SocketAddr) {
+    sink.send((
+        VoicePacket::Audio {
+            _dst: std::marker::PhantomData,
+            target: 0,
+            session_id: (),
+            seq_num: 0,
+            payload: VoicePacketPayload::Opus(Bytes::from([0u8; 128].as_ref()), true),
+            position_info: None,
+        },
+        server_addr,
+    ))
+    .await
+    .unwrap();
+}
+
+async fn send_voice(
+    sink: Arc<Mutex<UdpSender>>,
+    server_addr: SocketAddr,
+    audio: Arc<Mutex<Audio>>,
+) {
+    let mut receiver = audio.lock().unwrap().take_receiver().unwrap();
+
+    let mut count = 0;
+    while let Some(payload) = receiver.recv().await {
+        let reply = VoicePacket::Audio {
+            _dst: std::marker::PhantomData,
+            target: 0,      // normal speech
+            session_id: (), // unused for server-bound packets
+            seq_num: count,
+            payload,
+            position_info: None,
+        };
+        count += 1;
+        sink.lock()
+            .unwrap()
+            .send((reply, server_addr))
+            .await
+            .unwrap();
+    }
+}
+
+pub async fn handle(
+    server_addr: SocketAddr,
+    crypt_state: oneshot::Receiver<ClientCryptState>,
+    audio: Arc<Mutex<Audio>>,
+) {
+    let (mut sink, source) = connect(crypt_state).await;
+
+    // Note: A normal application would also send periodic Ping packets, and its own audio
+    //       via UDP. We instead trick the server into accepting us by sending it one
+    //       dummy voice packet.
+    send_ping(&mut sink, server_addr).await;
+
+    let sink = Arc::new(Mutex::new(sink));
+    join!(
+        listen(Arc::clone(&sink), source, Arc::clone(&audio)),
+        send_voice(sink, server_addr, audio)
+    );
+}