🚧 wip: finding a bug. It's in the udp_over_tcp code

When a TCP client disconnects, the rx loop gets confused and goes into an
infinite loop without ever yielding.

Cargo.lock

@@ -2418,6 +2418,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "tokio",
+ "tracing",
 ]
 
 [[package]]

crates/ptth_quic/src/executable_end_server.rs

@@ -100,7 +100,7 @@ pub struct P4EndServer {
 
 impl P4EndServer {
 	pub (crate) async fn connect (conf: Config) -> anyhow::Result <(Self, watch::Sender <bool>)> {
-		trace! ("P4 end server making its QUIC endpoint");
+		debug! ("P4 end server making its QUIC endpoint");
 		let endpoint = make_client_endpoint ("0.0.0.0:0".parse ()?, &[&conf.relay_cert])?;
 		
 		let conf = if conf.use_udp_over_tcp {
@@ -128,7 +128,7 @@ impl P4EndServer {
 			conf
 		};
 		
-		trace! ("P4 end server connecting to P3 relay server");
+		debug! ("P4 end server connecting to P3 relay server");
 		let conn = protocol::p4_connect_to_p3 (
 			&endpoint, 
 			conf.relay_addr, 

crates/ptth_quic/src/protocol.rs

@@ -257,7 +257,7 @@ pub async fn p4_connect_to_p3 (
 		bail! ("Server ID is longer than MAX_ID_LENGTH");
 	}
 	
-	let new_conn = endpoint.connect (relay_addr, "localhost")?.await?;
+	let new_conn = endpoint.connect (relay_addr, "localhost")?.await.context ("UXTDVL2V quinn::Endpoint::connect")?;
 	let (mut send, mut recv) = new_conn.open_bi ().await?;
 	let cmd_type = Command::CONNECT_P4_TO_P3.0;
 	
@@ -265,7 +265,7 @@ pub async fn p4_connect_to_p3 (
 	send_lv_string (&mut send, server_id).await?;
 	
 	expect_exact_response (&mut recv, [Command::OKAY.0, cmd_type, 0, 0]).await
-	.context ("P4 didn't get OK response when connecting to P3")?;
+	.context ("WMGW2RXU P4 didn't get OK response when connecting to P3")?;
 	
 	Ok (new_conn)
 }

crates/udp_over_tcp/Cargo.toml

@@ -6,5 +6,6 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-anyhow = "1.0.38"
+anyhow = "1.0.66"
-tokio = { version = "1.8.1", features = ["full"] }
+tokio = { version = "1.23.0", features = ["full"] }
+tracing = "0.1.37"

crates/udp_over_tcp/src/loops.rs

@@ -17,7 +17,12 @@ pub async fn rx (
 	udp_sock: Arc <UdpSocket>,
 	mut tcp_read: tcp::OwnedReadHalf,
 ) -> anyhow::Result <()> {
-	loop {
+	for i in 0u64.. {
+		// Optimizes down to a bitwise AND
+		if i % 8_192 == 0 {
+			tracing::trace! ("rx loop");
+		}
+		
 		let mut tag = [0u8, 0, 0, 0];
 		let bytes_read = tcp_read.read (&mut tag).await?;
 		if bytes_read != 4 {
@@ -47,6 +52,8 @@ pub async fn rx (
 		
 		udp_sock.send (&buf).await?;
 	}
+	
+	Ok (())
 }
 
 pub async fn tx (
@@ -54,7 +61,12 @@ pub async fn tx (
 	mut tcp_write: tcp::OwnedWriteHalf,
 ) -> anyhow::Result <()> 
 {
-	loop {
+	for i in 0u64.. {
+		// Optimizes down to a bitwise AND
+		if i % 8_192 == 0 {
+			tracing::trace! ("tx loop");
+		}
+		
 		let mut buf = vec! [0u8; 8_192];
 		let bytes_read = udp_sock.recv (&mut buf).await?;
 		buf.truncate (bytes_read);
@@ -66,4 +78,6 @@ pub async fn tx (
 		tcp_write.write_all (&length).await?;
 		tcp_write.write_all (&buf).await?;
 	}
+	
+	Ok (())
 }