update: both the downstream POCs work, with the bogus downstream.

Cargo.lock

@@ -1662,6 +1662,7 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "base64 0.12.3",
+ "clap",
  "futures",
  "reqwest",
  "rmp-serde",

crates/ptth_forwarding/Cargo.toml

@@ -9,6 +9,7 @@ edition = "2018"
 [dependencies]
 anyhow = "1.0.34"
 base64 = "0.12.3"
+clap = "2.33.3"
 futures = "0.3.7"
 reqwest = { version = "0.10.8", features = ["stream"] }
 rmp-serde = "0.14.4"

crates/ptth_forwarding/src/main.rs

@@ -1,16 +1,43 @@
+use clap::{App, SubCommand};
 use reqwest::Client;
 use tokio::{
 	io::AsyncWriteExt,
-	net::TcpStream,
+	net::{
+		TcpStream,
+		TcpListener,
+	},
 	stream::StreamExt,
 };
 
 #[tokio::main]
 async fn main () -> anyhow::Result <()> {
+	let matches = App::new ("ptth_forwarding")
+		.author ("Trish")
+		.about ("Terminator for PTTH port forwarding")
+		.subcommand (
+			SubCommand::with_name ("server")
+			.about ("Run this on the host with the TCP server")
+		)
+		.subcommand (
+			SubCommand::with_name ("client")
+			.about ("Run this on the host with the TCP client")
+		)
+	.get_matches ();
+	
 	let client = Client::builder ()
 	.build ()?;
 	
-	let mut tcp_stream = TcpStream::connect ("127.0.0.1:4010").await?;
+	let mut tcp_stream = if let Some (matches) = matches.subcommand_matches ("server") { 
+		TcpStream::connect ("127.0.0.1:4010").await?
+	}
+	else if let Some (matches) = matches.subcommand_matches ("client") {
+		let mut listener = TcpListener::bind ("127.0.0.1:4020").await?;
+		let (stream, _addr) = listener.accept ().await?;
+		stream
+	}
+	else {
+		panic! ("Must use server or client subcommand.");
+	};
 	
 	let resp = client.get ("http://127.0.0.1:4003/").send ().await?;
 	let mut downstream = resp.bytes_stream ();