diff --git a/prototypes/quic_demo/src/bin/quic_demo_end_server.rs b/prototypes/quic_demo/src/bin/quic_demo_end_server.rs
index 031a240..bd89bb8 100644
--- a/prototypes/quic_demo/src/bin/quic_demo_end_server.rs
+++ b/prototypes/quic_demo/src/bin/quic_demo_end_server.rs
@@ -39,20 +39,32 @@ async fn main () -> anyhow::Result <()> {
 	loop {
 		let (relay_send, relay_recv) = bi_streams.next ().await.ok_or_else (|| anyhow::anyhow! ("Relay server didn't open a bi stream"))??;
 		
-		tokio::spawn (handle_p2_connection (relay_send, relay_recv, local_tcp_port));
+		tokio::spawn (handle_bi_stream (relay_send, relay_recv, local_tcp_port));
 	}
 }
 
-async fn handle_p2_connection (
+async fn handle_bi_stream (
+	relay_send: quinn::SendStream,
+	mut relay_recv: quinn::RecvStream,
+	local_tcp_port: u16,
+) -> anyhow::Result <()>
+{
+	match protocol::p4_accept_p3_stream (&mut relay_recv).await? {
+		protocol::P3ToP4Stream::NewPtthConnection {
+			client_id,
+			..
+		} => handle_new_ptth_connection (relay_send, relay_recv, local_tcp_port).await?,
+	}
+	
+	Ok (())
+}
+
+async fn handle_new_ptth_connection (
 	mut relay_send: quinn::SendStream,
 	mut relay_recv: quinn::RecvStream,
 	local_tcp_port: u16,
 ) -> anyhow::Result <()>
 {
-	let mut req_buf = [0, 0, 0, 0];
-	relay_recv.read_exact (&mut req_buf).await?;
-	assert_eq! (req_buf [0], Command::CONNECT_P2_TO_P4_STEP_2.0);
-	
 	// TODO: Authorize P2 to connect to us
 	
 	let resp_buf = [
diff --git a/prototypes/quic_demo/src/protocol.rs b/prototypes/quic_demo/src/protocol.rs
index eeb791d..3103d47 100644
--- a/prototypes/quic_demo/src/protocol.rs
+++ b/prototypes/quic_demo/src/protocol.rs
@@ -1,3 +1,4 @@
+use anyhow::Result;
 use quinn::{
 	SendStream,
 	RecvStream,
@@ -17,11 +18,34 @@ impl Command {
 	pub const OKAY: Command = Command (20);
 }
 
+pub enum P3ToP4Stream {
+	NewPtthConnection {
+		client_id: u8,
+	}
+}
+
+pub async fn p4_accept_p3_stream (
+	recv: &mut RecvStream,
+) -> Result <P3ToP4Stream>
+{
+	let mut req_buf = [0, 0, 0, 0];
+	recv.read_exact (&mut req_buf).await?;
+	
+	let cmd_type = req_buf [0];
+	
+	Ok (match Command (cmd_type) {
+		Command::CONNECT_P2_TO_P4_STEP_2 => P3ToP4Stream::NewPtthConnection {
+			client_id: req_buf [1],
+		},
+		_ => bail! ("Invalid command type while P2 was accepting a new bi stream from P3"),
+	})
+}
+
 pub async fn p2_connect_to_p3 (
 	endpoint: &quinn::Endpoint,
 	relay_addr: &std::net::SocketAddr,
 	client_id: u8,
-) -> anyhow::Result <quinn::NewConnection> 
+) -> Result <quinn::NewConnection> 
 {
 	let new_conn = endpoint.connect (relay_addr, "localhost")?.await?;
 	let (mut send, mut recv) = new_conn.connection.open_bi ().await?;
@@ -38,7 +62,7 @@ pub async fn p2_connect_to_p3 (
 pub async fn p2_connect_to_p5 (
 	connection: &quinn::Connection,
 	server_id: u8,
-) -> anyhow::Result <(SendStream, RecvStream)>
+) -> Result <(SendStream, RecvStream)>
 {
 	let (mut send, mut recv) = connection.open_bi ().await?;
 	
@@ -67,7 +91,7 @@ pub async fn p4_connect_to_p3 (
 	endpoint: &quinn::Endpoint,
 	relay_addr: &std::net::SocketAddr,
 	server_id: u8,
-) -> anyhow::Result <quinn::NewConnection> 
+) -> Result <quinn::NewConnection> 
 {
 	let new_conn = endpoint.connect (relay_addr, "localhost")?.await?;
 	let (mut send, mut recv) = new_conn.connection.open_bi ().await?;
@@ -83,7 +107,7 @@ pub async fn p4_connect_to_p3 (
 
 async fn expect_exact_response (
 	recv: &mut RecvStream, expected: [u8; 4]
-) -> anyhow::Result <()>
+) -> Result <()>
 {
 	let mut resp_buf = [0, 0, 0, 0];
 	recv.read_exact (&mut resp_buf).await?;