feat: [torrust#625] a new UDP tracker client

You can use it with:

```console
cargo run --bin udp_tracker_client 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422
```

and the output should be something like:

```
AnnounceIpv4(
    AnnounceResponse {
        transaction_id: TransactionId(
            -888840697,
        ),
        announce_interval: AnnounceInterval(
            300,
        ),
        leechers: NumberOfPeers(
            0,
        ),
        seeders: NumberOfPeers(
            1,
        ),
        peers: [],
    },
)
```

src/bin/udp_tracker_client.rs

@@ -0,0 +1,110 @@
+use std::env;
+use std::net::Ipv4Addr;
+
+use aquatic_udp_protocol::common::InfoHash;
+use aquatic_udp_protocol::{
+    AnnounceEvent, AnnounceRequest, ConnectRequest, ConnectionId, NumberOfBytes, NumberOfPeers, PeerId, PeerKey, Port, Response,
+    TransactionId,
+};
+use log::{debug, LevelFilter};
+use torrust_tracker::shared::bit_torrent::tracker::udp::client::{UdpClient, UdpTrackerClient};
+
+#[tokio::main]
+async fn main() {
+    setup_logging(LevelFilter::Info);
+
+    let args: Vec<String> = env::args().collect();
+
+    if args.len() != 3 {
+        eprintln!("Error: invalid number of arguments!");
+        eprintln!("Usage:   cargo run --bin udp_tracker_client <UDP_TRACKER_SOCKET_ADDRESS> <INFO_HASH>");
+        eprintln!("Example: cargo run --bin udp_tracker_client 144.126.245.19:6969 9c38422213e30bff212b30c360d26f9a02136422");
+        std::process::exit(1);
+    }
+
+    let port = 0;
+    let transaction_id = -888_840_697;
+
+    let remote_socket_addr = &args[1];
+
+    let bind_to = format!("0.0.0.0:{port}");
+
+    debug!("Binding to: {bind_to}");
+
+    let udp_client = UdpClient::bind(&bind_to).await;
+
+    let bound_to = udp_client.socket.local_addr().unwrap();
+
+    debug!("Bound to:   {bound_to}");
+
+    debug!("Connecting to remote: udp://{remote_socket_addr}");
+
+    udp_client.connect(remote_socket_addr).await;
+
+    let udp_tracker_client = UdpTrackerClient { udp_client };
+
+    let connection_id = send_connection_request(TransactionId(transaction_id), &udp_tracker_client).await;
+
+    // Send announce request
+
+    let announce_request = AnnounceRequest {
+        connection_id: ConnectionId(connection_id.0),
+        transaction_id: TransactionId(transaction_id),
+        info_hash: InfoHash([0u8; 20]),
+        peer_id: PeerId([255u8; 20]),
+        bytes_downloaded: NumberOfBytes(0i64),
+        bytes_uploaded: NumberOfBytes(0i64),
+        bytes_left: NumberOfBytes(0i64),
+        event: AnnounceEvent::Started,
+        ip_address: Some(Ipv4Addr::new(0, 0, 0, 0)),
+        key: PeerKey(0u32),
+        peers_wanted: NumberOfPeers(1i32),
+        port: Port(bound_to.port()),
+    };
+
+    debug!("Sending announce request with connection id: {connection_id:#?}");
+
+    udp_tracker_client.send(announce_request.into()).await;
+
+    let response = udp_tracker_client.receive().await;
+
+    println!("{response:#?}");
+}
+
+async fn send_connection_request(transaction_id: TransactionId, client: &UdpTrackerClient) -> ConnectionId {
+    debug!("Sending connection request with transaction id: {transaction_id:#?}");
+
+    let connect_request = ConnectRequest { transaction_id };
+
+    client.send(connect_request.into()).await;
+
+    let response = client.receive().await;
+
+    debug!("response:\n{response:#?}");
+
+    match response {
+        Response::Connect(connect_response) => connect_response.connection_id,
+        _ => panic!("error connecting to udp server. Unexpected response"),
+    }
+}
+
+fn setup_logging(level: LevelFilter) {
+    if let Err(_err) = fern::Dispatch::new()
+        .format(|out, message, record| {
+            out.finish(format_args!(
+                "{} [{}][{}] {}",
+                chrono::Local::now().format("%+"),
+                record.target(),
+                record.level(),
+                message
+            ));
+        })
+        .level(level)
+        .chain(std::io::stdout())
+        .apply()
+    {
+        panic!("Failed to initialize logging.")
+    }
+
+    debug!("logging initialized.");
+}

src/shared/bit_torrent/tracker/udp/client.rs

@@ -4,6 +4,7 @@ use std::sync::Arc;
 use std::time::Duration;
 
 use aquatic_udp_protocol::{ConnectRequest, Request, Response, TransactionId};
+use log::debug;
 use tokio::net::UdpSocket;
 use tokio::time;
 
@@ -19,7 +20,12 @@ impl UdpClient {
     ///
     /// Will panic if the local address can't be bound.
     pub async fn bind(local_address: &str) -> Self {
-        let socket = UdpSocket::bind(local_address).await.unwrap();
+        let valid_socket_addr = local_address
+            .parse::<SocketAddr>()
+            .unwrap_or_else(|_| panic!("{local_address} is not a valid socket address"));
+
+        let socket = UdpSocket::bind(valid_socket_addr).await.unwrap();
+
         Self {
             socket: Arc::new(socket),
         }
@@ -29,7 +35,14 @@ impl UdpClient {
     ///
     /// Will panic if can't connect to the socket.
     pub async fn connect(&self, remote_address: &str) {
-        self.socket.connect(remote_address).await.unwrap();
+        let valid_socket_addr = remote_address
+            .parse::<SocketAddr>()
+            .unwrap_or_else(|_| panic!("{remote_address} is not a valid socket address"));
+
+        match self.socket.connect(valid_socket_addr).await {
+            Ok(()) => debug!("Connected successfully"),
+            Err(e) => panic!("Failed to connect: {e:?}"),
+        }
     }
 
     /// # Panics
@@ -39,6 +52,8 @@ impl UdpClient {
     /// - Can't write to the socket.
     /// - Can't send data.
     pub async fn send(&self, bytes: &[u8]) -> usize {
+        debug!(target: "UDP client", "send {bytes:?}");
+
         self.socket.writable().await.unwrap();
         self.socket.send(bytes).await.unwrap()
     }
@@ -50,8 +65,15 @@ impl UdpClient {
     /// - Can't read from the socket.
     /// - Can't receive data.
     pub async fn receive(&self, bytes: &mut [u8]) -> usize {
+        debug!(target: "UDP client", "receiving ...");
+
         self.socket.readable().await.unwrap();
-        self.socket.recv(bytes).await.unwrap()
+
+        let size = self.socket.recv(bytes).await.unwrap();
+
+        debug!(target: "UDP client", "{size} bytes received {bytes:?}");
+
+        size
     }
 }
 
@@ -73,6 +95,8 @@ impl UdpTrackerClient {
     ///
     /// Will panic if can't write request to bytes.
     pub async fn send(&self, request: Request) -> usize {
+        debug!(target: "UDP tracker client", "send request {request:?}");
+
         // Write request into a buffer
         let request_buffer = vec![0u8; MAX_PACKET_SIZE];
         let mut cursor = Cursor::new(request_buffer);
@@ -99,6 +123,8 @@ impl UdpTrackerClient {
 
         let payload_size = self.udp_client.receive(&mut response_buffer).await;
 
+        debug!(target: "UDP tracker client", "received {payload_size} bytes. Response {response_buffer:?}");
+
         Response::from_bytes(&response_buffer[..payload_size], true).unwrap()
     }
 }

tests/servers/udp/contract.rs

@@ -118,6 +118,8 @@ mod receiving_an_announce_request {
 
         let response = client.receive().await;
 
+        println!("test response {response:?}");
+
         assert!(is_ipv4_announce_response(&response));
     }
 }