♻️ refactor: start moving protocol chunks out of exe modules

prototypes/quic_demo/src/bin/quic_demo_client.rs

@@ -39,22 +39,7 @@ async fn main () -> anyhow::Result <()> {
 	let client_id = opt.client_id.unwrap_or (42);
 	let server_id = opt.server_id.unwrap_or (43);
 	
-	let req_buf = [
+	protocol::p2_connect_to_p3 (&mut send, &mut recv, client_id).await?;
-		Command::CONNECT_P2_TO_P3.0, 
-		client_id, 
-		0, 
-		0,
-	];
-	send.write_all (&req_buf).await?;
-	
-	let mut resp_buf = [0, 0, 0, 0];
-	recv.read_exact (&mut resp_buf).await?;
-	assert_eq! (resp_buf, [
-		Command::OKAY.0, 
-		Command::CONNECT_P2_TO_P3.0, 
-		0, 
-		0,
-	]);
 	
 	let listener = TcpListener::bind (("127.0.0.1", local_tcp_port)).await?;
 	

prototypes/quic_demo/src/protocol.rs

@@ -1,3 +1,10 @@
+use quinn::{
+	SendStream,
+	RecvStream,
+};
+
+use crate::prelude::*;
+
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub struct Command (pub u8);
 
@@ -10,4 +17,32 @@ impl Command {
 	pub const OKAY: Command = Command (20);
 }
 
-// pub fn p2_connect_to_p3 (
+pub async fn p2_connect_to_p3 (
+	send: &mut SendStream, 
+	recv: &mut RecvStream, 
+	client_id: u8,
+) 
+-> anyhow::Result <()> 
+{
+	let req_buf = [
+		Command::CONNECT_P2_TO_P3.0, 
+		client_id, 
+		0, 
+		0,
+	];
+	send.write_all (&req_buf).await?;
+	
+	let mut resp_buf = [0, 0, 0, 0];
+	recv.read_exact (&mut resp_buf).await?;
+	let expected = [
+		Command::OKAY.0, 
+		Command::CONNECT_P2_TO_P3.0, 
+		0, 
+		0,
+	];
+	if resp_buf != expected {
+		bail! ("P2 didn't get OK response when connecting to P3");
+	}
+	
+	Ok (())
+}