💄 change it to just pick a client port automatically.

This is a lot less thinking for the user. (such as me)

Cargo.lock

@@ -1216,10 +1216,15 @@ name = "ptth_quic_client_gui"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "blake3",
  "fltk",
  "quic_demo",
  "quinn",
+ "rand",
+ "rand_chacha",
  "reqwest",
+ "rmp-serde",
+ "serde",
  "structopt",
  "tokio",
  "tracing",

prototypes/ptth_quic_client_gui/Cargo.toml

@@ -9,10 +9,15 @@ license = "AGPL-3.0"
 
 [dependencies]
 anyhow = "1.0.38"
+blake3 = "1.0.0"
 fltk = "1.2.7"
 quic_demo = { path = "../quic_demo" }
 quinn = "0.7.2"
+rand = "0.8.4"
+rand_chacha = "0.3.1"
 reqwest = "0.11.4"
+rmp-serde = "0.15.5"
+serde = "1.0.130"
 structopt = "0.3.20"
 tokio = { version = "1.8.1", features = ["full"] }
 tracing-subscriber = "0.2.16"

prototypes/ptth_quic_client_gui/src/main.rs

@@ -12,6 +12,10 @@ use fltk::{
 	prelude::*, 
 	window::Window
 };
+use rand::{
+	Rng,
+	SeedableRng,
+};
 use structopt::StructOpt;
 use tokio::runtime::Runtime;
 
@@ -51,6 +55,27 @@ struct Port {
 	forwarding_instance: Option <ForwardingInstance>,
 }
 
+impl Port {
+	pub fn open_port (&mut self, rt: &Runtime, connection_p2_p3: quinn::Connection)
+	-> anyhow::Result <()> 
+	{
+		let params = self.gui.get_params ()?;
+		
+		let _guard = rt.enter ();
+		let forwarding_instance = rt.block_on (ForwardingInstance::new (
+			connection_p2_p3,
+			params,
+		))?;
+		
+		self.gui.input_client_port.set_value (&forwarding_instance.local_port ().to_string ());
+		
+		self.forwarding_instance.replace (forwarding_instance);
+		self.gui.set_forwarding (true);
+		
+		Ok (())
+	}
+}
+
 struct GuiPort {
 	row: fltk::group::Flex,
 	input_client_port: Input,
@@ -67,17 +92,7 @@ impl GuiClient <'_> {
 		port_idx: usize,
 	) -> anyhow::Result <()>
 	{
-		let params = self.ports [port_idx].gui.get_params ()?;
+		self.ports [port_idx].open_port (&self.rt, connection_p2_p3)?;
-		
-		let _guard = self.rt.enter ();
-		let forwarding_instance = self.rt.block_on (ForwardingInstance::new (
-			connection_p2_p3,
-			params,
-		))?;
-		
-		self.ports [port_idx].forwarding_instance.replace (forwarding_instance);
-		
-		self.ports [port_idx].gui.set_forwarding (true);
 		self.sync_status ();
 		
 		Ok (())
@@ -152,12 +167,12 @@ fn main () -> anyhow::Result <()> {
 	{
 		let mut row = Flex::default ().row ();
 		
-		let mut l = Frame::default ().with_label ("Local port");
-		row.set_size (&mut l, 80);
 		let mut l = Frame::default ().with_label ("Server ID");
 		row.set_size (&mut l, 120);
 		let mut l = Frame::default ().with_label ("Server port");
 		row.set_size (&mut l, 80);
+		let mut l = Frame::default ().with_label ("Local port");
+		row.set_size (&mut l, 80);
 		row.end ();
 		
 		col.set_size (&mut row, 30);
@@ -249,19 +264,20 @@ impl GuiPort {
 		
 		let mut row = Flex::default ().row ();
 		
-		let mut input_client_port = Input::default ();
 		let mut input_server_id = Input::default ();
 		let mut input_server_port = Input::default ();
+		let mut input_client_port = Input::default ();
 		let mut but_open = Button::default ().with_label ("Open");
 		let mut but_close = Button::default ().with_label ("Close");
 		
-		row.set_size (&mut input_client_port, 80);
 		row.set_size (&mut input_server_id, 120);
 		row.set_size (&mut input_server_port, 80);
+		row.set_size (&mut input_client_port, 80);
 		row.set_size (&mut but_open, 80);
 		row.set_size (&mut but_close, 80);
 		
-		input_client_port.set_value ("5901");
+		input_client_port.set_value ("");
+		input_client_port.set_readonly (true);
 		input_server_id.set_value ("bogus_server");
 		input_server_port.set_value ("5900");
 		
@@ -270,26 +286,32 @@ impl GuiPort {
 		but_close.set_trigger (CallbackTrigger::Release);
 		but_close.emit (fltk_tx, Message::ClosePort (port_idx));
 		
-		set_active (&mut but_open, true);
-		set_active (&mut but_close, false);
-		
 		row.end ();
 		
-		Self {
+		let mut output = Self {
 			row,
 			input_client_port,
 			input_server_id,
 			input_server_port,
 			but_open,
 			but_close,
-		}
+		};
+		
+		output.set_forwarding (false);
+		
+		output
 	}
 	
 	fn get_params (&self) -> anyhow::Result <ForwardingParams>
 	{
-		let client_tcp_port = u16::from_str (&self.input_client_port.value ())?;
-		let server_id = self.input_server_id.value ();
 		let server_tcp_port = u16::from_str (&self.input_server_port.value ())?;
+		let server_id = self.input_server_id.value ();
+		
+		let client_tcp_port = PortInfo {
+			relay_addr: "bogus_relay",
+			server_id: &server_id,
+			server_tcp_port,
+		}.random_eph_port ();
 		
 		Ok (ForwardingParams {
 			client_tcp_port,
@@ -299,7 +321,7 @@ impl GuiPort {
 	}
 	
 	fn set_forwarding (&mut self, x: bool) {
-		set_active (&mut self.input_client_port, !x);
+		set_active (&mut self.input_client_port, x);
 		set_active (&mut self.input_server_id, !x);
 		set_active (&mut self.input_server_port, !x);
 		set_active (&mut self.but_open, !x);
@@ -309,3 +331,63 @@ impl GuiPort {
 		self.but_close.set (!x);
 	}
 }
+
+// This can collide, but who cares
+// It's not secure or anything - It's just supposed to pick a port somewhat
+// deterministically based on the server and relay info.
+
+#[derive (serde::Serialize)]
+struct PortInfo <'a> {
+	relay_addr: &'a str,
+	server_id: &'a str,
+	server_tcp_port: u16
+}
+
+impl PortInfo <'_> {
+	// https://en.wikipedia.org/wiki/TCP_ports#Dynamic,_private_or_ephemeral_ports
+	
+	fn random_eph_port (&self) -> u16
+	{
+		let seed = blake3::hash (&rmp_serde::to_vec (self).expect ("Can't hash PortInfo - impossible error"));
+		
+		let mut rng = rand_chacha::ChaCha20Rng::from_seed (*seed.as_bytes ());
+		
+		let tcp_eph_range = 49152..=65535;
+		rng.gen_range (tcp_eph_range)
+	}
+}
+
+#[cfg (test)]
+mod test {
+	use blake3::Hasher;
+	
+	use super::*;
+	
+	#[test]
+	fn prng () {
+		let hasher = Hasher::default ();
+		let seed = hasher.finalize ();
+		
+		let mut rng = rand_chacha::ChaCha20Rng::from_seed (*seed.as_bytes ());
+		
+		let tcp_eph_range = 49152..=65535;
+		let port = rng.gen_range (tcp_eph_range);
+		assert_eq! (port, 49408);
+		
+		for (input, expected) in vec! [
+			(("bogus_relay", "bogus_server",   22), 62350),
+			(("real_relay",  "bogus_server",   22), 61081),
+			(("bogus_relay", "real_server",    22), 50513),
+			(("bogus_relay", "bogus_server", 5900), 60730),
+		] {
+			let (relay_addr, server_id, server_tcp_port) = input;
+			let input = PortInfo {
+				relay_addr,
+				server_id,
+				server_tcp_port,
+			};
+			let actual = input.random_eph_port ();
+			assert_eq! (expected, actual);
+		}
+	}
+}

prototypes/quic_demo/src/client_proxy.rs

@@ -9,6 +9,7 @@ use crate::prelude::*;
 pub struct ForwardingInstance {
 	task: JoinHandle <anyhow::Result <()>>,
 	shutdown_flag: watch::Sender <bool>,
+	local_port: u16,
 }
 
 impl ForwardingInstance {
@@ -20,7 +21,8 @@ impl ForwardingInstance {
 		let (shutdown_flag, shutdown_flag_rx) = tokio::sync::watch::channel (true);
 		
 		let listener = TcpListener::bind (("127.0.0.1", params.client_tcp_port)).await?;
-		trace! ("Accepting local TCP connections from P1 on {}", params.client_tcp_port);
+		let local_port = listener.local_addr ()?.port ();
+		trace! ("Accepting local TCP connections from P1 on {}", local_port);
 		
 		let task = tokio::spawn (forward_port (
 			listener,
@@ -32,6 +34,7 @@ impl ForwardingInstance {
 		Ok (Self {
 			task,
 			shutdown_flag,
+			local_port,
 		})
 	}
 	
@@ -44,6 +47,10 @@ impl ForwardingInstance {
 		.context ("inside ForwardingInstance task")?;
 		Ok (())
 	}
+	
+	pub fn local_port (&self) -> u16 {
+		self.local_port
+	}
 }
 
 pub struct ForwardingParams {