🚧 wip: not working the way I expect

Release build only went from 1.9 to 2.0 MB, but that could cause I'm not really using Tokio yet

Cargo.lock

@@ -43,6 +43,15 @@ version = "0.2.109"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f98a04dce437184842841303488f70d0188c5f51437d2a834dc097eafa909a01"
 
+[[package]]
+name = "log"
+version = "0.4.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "51b9bbe6c47d51fc3e1a9b945965946b4c44142ab8792c50835a980d362c2710"
+dependencies = [
+ "cfg-if",
+]
+
 [[package]]
 name = "lookaround"
 version = "0.1.4"
@@ -50,6 +59,7 @@ dependencies = [
  "mac_address",
  "rand",
  "thiserror",
+ "tokio",
 ]
 
 [[package]]
@@ -71,6 +81,28 @@ dependencies = [
  "autocfg",
 ]
 
+[[package]]
+name = "mio"
+version = "0.7.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8067b404fe97c70829f082dec8bcf4f71225d7eaea1d8645349cb76fa06205cc"
+dependencies = [
+ "libc",
+ "log",
+ "miow",
+ "ntapi",
+ "winapi",
+]
+
+[[package]]
+name = "miow"
+version = "0.3.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b9f1c5b025cda876f66ef43a113f91ebc9f4ccef34843000e0adf6ebbab84e21"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "nix"
 version = "0.22.2"
@@ -84,6 +116,21 @@ dependencies = [
  "memoffset",
 ]
 
+[[package]]
+name = "ntapi"
+version = "0.3.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f6bb902e437b6d86e03cce10a7e2af662292c5dfef23b65899ea3ac9354ad44"
+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "pin-project-lite"
+version = "0.2.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8d31d11c69a6b52a174b42bdc0c30e5e11670f90788b2c471c31c1d17d449443"
+
 [[package]]
 name = "ppv-lite86"
 version = "0.2.15"
@@ -179,6 +226,19 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "tokio"
+version = "1.14.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70e992e41e0d2fb9f755b37446f20900f64446ef54874f40a60c78f021ac6144"
+dependencies = [
+ "autocfg",
+ "libc",
+ "mio",
+ "pin-project-lite",
+ "winapi",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.2"

Cargo.toml

@@ -15,9 +15,9 @@ version = "0.1.4"
 mac_address = "1.1.2"
 rand = "0.8.4"
 thiserror = "1.0.30"
+tokio = { version = "1.14.0", features = ["fs", "net", "rt", "time"] }
 
 [profile.release]
 codegen-units = 1
 lto = true
 opt-level = "z"
-panic = "abort"

ideas.md

@@ -3,3 +3,4 @@ Cool ideas that can be done but probably won't be.
 - Command for shell substituting IPs into commands
 - Arbitrary TCP forwarding of (stdin? stdout? TCP?)
 - Netcat replacement "Just send a file" _including filename_
+- Public-key crypto for trusting peers on first use (Hard cause it requires mutable disk state)

issues.md

@@ -21,12 +21,3 @@ and get their IPs, so I might have to find another dependency
 for that. I think on Linux I can get it from `/sys/class/net` but
 I can't remember the trick for that. I think last time I did this
 (for that work project) I just punted to Qt.
-
-# 01FPDWYH3ZY52DFF6PNRSA63GB
-
-Sending an invalid packet directly to the server's UDP port crashes the server.
-
-# 01FPDY51GHC7NRFV7Z14Q1KV7N
-
-Remove all unwraps. Since I used abort-on-panic to make the binary smaller,
-it's not giving any error message for panics

src/app_common.rs

@@ -0,0 +1,61 @@
+use crate::prelude::*;
+
+#[derive (Debug, thiserror::Error)]
+pub enum AppError {
+	#[error (transparent)]
+	AddrParse (#[from] std::net::AddrParseError),
+	#[error (transparent)]
+	CliArgs (#[from] CliArgError),
+	#[error (transparent)]
+	Io (#[from] std::io::Error),
+	#[error (transparent)]
+	Ip (#[from] crate::ip::IpError),
+	#[error (transparent)]
+	Join (#[from] tokio::task::JoinError),
+	#[error (transparent)]
+	MacAddr (#[from] mac_address::MacAddressError),
+	#[error (transparent)]
+	Message (#[from] crate::message::MessageError),
+	#[error (transparent)]
+	Tlv (#[from] crate::tlv::TlvError),
+}
+
+#[derive (Debug, thiserror::Error)]
+pub enum CliArgError {
+	#[error ("Missing value for argument `{0}`")]
+	MissingArgumentValue (String),
+	#[error ("First argument should be a subcommand")]
+	MissingSubcommand,
+	#[error ("Unknown subcommand `{0}`")]
+	UnknownSubcommand (String),
+	#[error ("Unrecognized argument `{0}`")]
+	UnrecognizedArgument (String),
+}
+
+pub async fn recv_msg_from (socket: &UdpSocket) -> Result <(Vec <Message>, SocketAddr), AppError> 
+{
+	let mut buf = vec! [0u8; PACKET_SIZE];
+	let (bytes_recved, remote_addr) = socket.recv_from (&mut buf).await?;
+	buf.truncate (bytes_recved);
+	let msgs = Message::from_slice2 (&buf)?;
+	
+	Ok ((msgs, remote_addr))
+}
+
+#[derive (Clone)]
+pub struct Params {
+	// Servers bind on this port, clients must send to the port
+	pub server_port: u16,
+	
+	// Clients and servers will all join the same multicast addr
+	pub multicast_addr: Ipv4Addr,
+}
+
+impl Default for Params {
+	fn default () -> Self {
+		Self {
+			server_port: 9040,
+			multicast_addr: Ipv4Addr::new (225, 100, 99, 98),
+		}
+	}
+}

src/client.rs

@@ -0,0 +1,99 @@
+use crate::prelude::*;
+
+struct ServerResponse {
+	mac: Option <[u8; 6]>,
+	nickname: Option <String>,
+}
+
+pub async fn client <I : Iterator <Item=String>> (mut args: I) -> Result <(), AppError> {
+	use rand::RngCore;
+	
+	let common_params = app_common::Params::default ();
+	let mut bind_addr = "0.0.0.0".to_string ();
+	
+	while let Some (arg) = args.next () {
+		match arg.as_str () {
+			"--bind-addr" => {
+				bind_addr = match args.next () {
+					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
+					Some (x) => x
+				};
+			},
+			_ => return Err (CliArgError::UnrecognizedArgument (arg).into ()),
+		}
+	}
+	
+	let socket = UdpSocket::bind (&format! ("{}:0", bind_addr)).await?;
+	
+	socket.join_multicast_v4 (common_params.multicast_addr, Ipv4Addr::from_str (&bind_addr)?)?;
+	
+	let mut idem_id = [0u8; 8];
+	rand::thread_rng ().fill_bytes (&mut idem_id);
+	
+	let msg = Message::Request1 {
+		idem_id,
+		mac: None,
+	}.to_vec ()?;
+	
+	for _ in 0..10 {
+		socket.send_to (&msg, (common_params.multicast_addr, common_params.server_port)).await?;
+		sleep (Duration::from_millis (100)).await;
+	}
+	
+	let mut peers = HashMap::with_capacity (10);
+	
+	timeout (Duration::from_secs (2), listen_for_responses (&socket, &mut peers)).await.ok ();
+	
+	let mut peers: Vec <_> = peers.into_iter ().collect ();
+	peers.sort_by_key (|(_, v)| v.mac);
+	
+	println! ("Found {} peers:", peers.len ());
+	for (ip, resp) in peers.into_iter () {
+		let mac = match resp.mac {
+			None => {
+				println! ("<Unknown> = {}", ip);
+				continue;
+			},
+			Some (x) => x,
+		};
+		
+		let nickname = match resp.nickname {
+			None => {
+				println! ("{} = {}", MacAddress::new (mac), ip.ip ());
+				continue;
+			},
+			Some (x) => x,
+		};
+		
+		println! ("{} = {} `{}`", MacAddress::new (mac), ip.ip (), nickname);
+	}
+	
+	Ok (())
+}
+
+async fn listen_for_responses (
+	socket: &UdpSocket, 
+	peers: &mut HashMap <SocketAddr, ServerResponse>
+) {
+	loop {
+		let (msgs, remote_addr) = match recv_msg_from (socket).await {
+			Err (_) => continue,
+			Ok (x) => x,
+		};
+		
+		let mut resp = ServerResponse {
+			mac: None,
+			nickname: None,
+		};
+		
+		for msg in msgs.into_iter () {
+			match msg {
+				Message::Response1 (x) => resp.mac = x,
+				Message::Response2 (x) => resp.nickname = Some (x.nickname),
+				_ => (),
+			}
+		}
+		
+		peers.insert (remote_addr, resp);
+	}
+}

src/ip.rs

@@ -4,9 +4,40 @@ use std::{
 	str::FromStr,
 };
 
-use crate::AppError;
+#[derive (Debug, thiserror::Error)]
+pub enum IpError {
+	#[error (transparent)]
+	Io (#[from] std::io::Error),
+	#[error (transparent)]
+	FromUtf8 (#[from] std::string::FromUtf8Error),
+	#[error ("Self-IP detection is not implemented on Mac OS")]
+	NotImplementedOnMac,
+}
 
-pub fn get_ip_addr_output () -> Result <String, AppError> {
+#[cfg(target_os = "linux")]
+pub fn get_ips () -> Result <Vec <Ipv4Addr>, IpError> {
+	let output = linux::get_ip_addr_output ()?;
+	
+	Ok (linux::parse_ip_addr_output (&output))
+}
+
+#[cfg(target_os = "macos")]
+pub fn get_ips () -> Result <Vec <Ipv4Addr>, IpError> {
+	Err (IpError::NotImplementedOnMac)
+}
+
+#[cfg(target_os = "windows")]
+pub fn get_ips () -> Result <Vec <Ipv4Addr>, IpError> {
+	let output = windows::get_ip_config_output ()?;
+	
+	Ok (windows::parse_ip_config_output (&output))
+}
+
+#[cfg(target_os = "linux")]
+pub mod linux {
+	use super::*;
+	
+	pub fn get_ip_addr_output () -> Result <String, IpError> {
 		let output = Command::new ("ip")
 		.arg ("addr")
 		.output ()?;
@@ -23,10 +54,16 @@ pub fn parse_ip_addr_output (output: &str) -> Vec <Ipv4Addr> {
 		.filter_map (|l| l.strip_prefix ("inet "))
 		.filter_map (|l| l.find ('/').map (|x| &l [0..x]))
 		.filter_map (|l| Ipv4Addr::from_str (l).ok ())
+		.filter (|a| ! a.is_loopback ())
 		.collect ()
 	}
+}
 
-pub fn get_ip_config_output () -> Result <String, AppError> {
+#[cfg(target_os = "windows")]
+pub mod windows {
+	use super::*;
+	
+	pub fn get_ip_config_output () -> Result <String, IpError> {
 		let output = Command::new ("ipconfig")
 		.output ()?;
 		let output = output.stdout.as_slice ();
@@ -60,3 +97,26 @@ pub fn parse_ip_config_output (output: &str) -> Vec <Ipv4Addr> {
 		
 		addrs
 	}
+
+	#[cfg (test)]
+	mod test {
+		use super::*;
+		
+		#[test]
+		fn test () {
+			for (input, expected) in [
+				(
+					r"
+	IPv4 Address .   .  .. . . . : 192.168.1.1
+	",
+					vec! [
+						Ipv4Addr::new (192, 168, 1, 1),
+					]
+				),
+			] {
+				let actual = parse_ip_config_output (input);
+				assert_eq! (actual, expected);
+			}
+		}
+	}
+}

src/main.rs

@@ -1,81 +1,25 @@
-use std::{
+use prelude::*;
-	collections::HashMap,
-	env,
-	net::{
-		Ipv4Addr,
-		SocketAddr,
-		SocketAddrV4,
-		UdpSocket,
-	},
-	str::FromStr,
-	time::{Duration, Instant},
-};
-
-use mac_address::{
-	MacAddress,
-	get_mac_address,
-};
-use thiserror::Error;
 
+pub mod app_common;
+mod client;
 mod ip;
-mod message;
+pub mod message;
+mod prelude;
+mod server;
 mod tlv;
 
-use message::{
-	PACKET_SIZE,
-	Message,
-};
-
-#[derive (Debug, Error)]
-pub enum AppError {
-	#[error (transparent)]
-	AddrParse (#[from] std::net::AddrParseError),
-	#[error (transparent)]
-	CliArgs (#[from] CliArgError),
-	#[error (transparent)]
-	FromUtf8 (#[from] std::string::FromUtf8Error),
-	#[error (transparent)]
-	Io (#[from] std::io::Error),
-	#[error (transparent)]
-	MacAddr (#[from] mac_address::MacAddressError),
-	#[error (transparent)]
-	Message (#[from] message::MessageError),
-	#[error (transparent)]
-	Tlv (#[from] tlv::TlvError),
-	#[error (transparent)]
-	Utf8 (#[from] std::str::Utf8Error),
-}
-
-#[derive (Debug, Error)]
-pub enum CliArgError {
-	#[error ("Missing value for argument `{0}`")]
-	MissingArgumentValue (String),
-	#[error ("First argument should be a subcommand")]
-	MissingSubcommand,
-	#[error ("Unknown subcommand `{0}`")]
-	UnknownSubcommand (String),
-	#[error ("Unrecognized argument `{0}`")]
-	UnrecognizedArgument (String),
-}
-
-struct CommonParams {
-	// Servers bind on this port, clients must send to the port
-	server_port: u16,
-	
-	// Clients and servers will all join the same multicast addr
-	multicast_addr: Ipv4Addr,
-}
-
-impl Default for CommonParams {
-	fn default () -> Self {
-		Self {
-			server_port: 9040,
-			multicast_addr: Ipv4Addr::new (225, 100, 99, 98),
-		}
-	}
-}
-
 fn main () -> Result <(), AppError> {
+	let rt = tokio::runtime::Builder::new_current_thread ()
+	.enable_io ()
+	.enable_time ()
+	.build ()?;
+	
+	rt.block_on (async_main ())?;
+	
+	Ok (())
+}
+
+async fn async_main () -> Result <(), AppError> {
 	let mut args = env::args ();
 	
 	let _exe_name = args.next ();
@@ -92,223 +36,20 @@ fn main () -> Result <(), AppError> {
 	
 	match subcommand.as_ref ().map (|x| &x[..]) {
 		None => return Err (CliArgError::MissingSubcommand.into ()),
-		Some ("client") => client (args)?,
+		Some ("client") => client::client (args).await?,
 		Some ("my-ips") => my_ips ()?,
-		Some ("server") => server (args)?,
+		Some ("server") => server::server (args).await?,
 		Some (x) => return Err (CliArgError::UnknownSubcommand (x.to_string ()).into ()),
 	}
 	
 	Ok (())
 }
 
-#[cfg(target_os = "linux")]
 fn my_ips () -> Result <(), AppError> {
-	let output = ip::get_ip_addr_output ()?;
+	for addr in ip::get_ips ()?
-	
-	for addr in ip::parse_ip_addr_output (&output)
-	.iter ()
-	.filter (|a| ! a.is_loopback ())
 	{
 		println! ("{:?}", addr);
 	}
 	
 	Ok (())
 }
-
-#[cfg(target_os = "macos")]
-fn my_ips () -> Result <(), AppError> {
-	println! ("my-ips subcommand not implemented for macos");
-	Ok (())
-}
-
-#[cfg(target_os = "windows")]
-fn my_ips () -> Result <(), AppError> {
-	let output = ip::get_ip_config_output ()?;
-	
-	for addr in ip::parse_ip_config_output (&output) {
-		println! ("{:?}", addr);
-	}
-	
-	Ok (())
-}
-
-struct ServerResponse {
-	mac: Option <[u8; 6]>,
-	nickname: Option <String>,
-}
-
-fn client <I : Iterator <Item=String>> (mut args: I) -> Result <(), AppError> {
-	use rand::RngCore;
-	
-	let mut common_params = CommonParams::default ();
-	let mut bind_addr = "0.0.0.0".to_string ();
-	
-	while let Some (arg) = args.next () {
-		match arg.as_str () {
-			"--bind-addr" => {
-				bind_addr = match args.next () {
-					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
-					Some (x) => x
-				};
-			},
-			_ => return Err (CliArgError::UnrecognizedArgument (arg).into ()),
-		}
-	}
-	
-	let socket = UdpSocket::bind (&format! ("{}:0", bind_addr))?;
-	
-	socket.join_multicast_v4 (&common_params.multicast_addr, &Ipv4Addr::from_str (&bind_addr)?)?;
-	socket.set_read_timeout (Some (Duration::from_millis (1_000)))?;
-	
-	let mut idem_id = [0u8; 8];
-	rand::thread_rng ().fill_bytes (&mut idem_id);
-	
-	let msg = Message::Request1 {
-		idem_id,
-		mac: None,
-	}.to_vec ()?;
-	
-	for _ in 0..10 {
-		socket.send_to (&msg, (common_params.multicast_addr, common_params.server_port))?;
-		std::thread::sleep (Duration::from_millis (100));
-	}
-	
-	let start_time = Instant::now ();
-	
-	let mut peers = HashMap::with_capacity (10);
-	
-	while Instant::now () < start_time + Duration::from_secs (2) {
-		let (msgs, remote_addr) = match recv_msg_from (&socket) {
-			Err (_) => continue,
-			Ok (x) => x,
-		};
-		
-		let mut resp = ServerResponse {
-			mac: None,
-			nickname: None,
-		};
-		
-		for msg in msgs.into_iter () {
-			match msg {
-				Message::Response1 (x) => resp.mac = x,
-				Message::Response2 (x) => resp.nickname = Some (x.nickname),
-				_ => (),
-			}
-		}
-		
-		peers.insert (remote_addr, resp);
-	}
-	
-	let mut peers: Vec <_> = peers.into_iter ().collect ();
-	peers.sort_by_key (|(k, v)| v.mac);
-	
-	println! ("Found {} peers:", peers.len ());
-	for (ip, resp) in peers.into_iter () {
-		let mac = match resp.mac {
-			None => {
-				println! ("<Unknown> = {}", ip);
-				continue;
-			},
-			Some (x) => x,
-		};
-		
-		let nickname = match resp.nickname {
-			None => {
-				println! ("{} = {}", MacAddress::new (mac), ip.ip ());
-				continue;
-			},
-			Some (x) => x,
-		};
-		
-		println! ("{} = {} `{}`", MacAddress::new (mac), ip.ip (), nickname);
-	}
-	
-	Ok (())
-}
-
-fn server <I: Iterator <Item=String>> (mut args: I) -> Result <(), AppError> 
-{
-	let mut common_params = CommonParams::default ();
-	let mut bind_addr = "0.0.0.0".to_string ();
-	let mut nickname = String::new ();
-	
-	while let Some (arg) = args.next () {
-		match arg.as_str () {
-			"--bind-addr" => {
-				bind_addr = match args.next () {
-					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
-					Some (x) => x
-				};
-			},
-			"--nickname" => {
-				nickname = match args.next () {
-					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
-					Some (x) => x
-				};
-			},
-			_ => return Err (CliArgError::UnrecognizedArgument (arg).into ()),
-		}
-	}
-	
-	let our_mac = get_mac_address ()?.map (|x| x.bytes ());
-	if our_mac.is_none () {
-		println! ("Warning: Can't find our own MAC address. We won't be able to respond to MAC-specific lookaround requests");
-	}
-	
-	let socket = UdpSocket::bind (SocketAddrV4::new (Ipv4Addr::from_str (&bind_addr)?, common_params.server_port)).unwrap ();
-	
-	socket.join_multicast_v4 (&common_params.multicast_addr, &([0u8, 0, 0, 0].into ())).unwrap ();
-	
-	let mut recent_idem_ids = Vec::with_capacity (32);
-	
-	loop {
-		println! ("Waiting for messages...");
-		let (req_msgs, remote_addr) = recv_msg_from (&socket)?;
-		
-		let req = match req_msgs.into_iter ().next () {
-			Some (x) => x,
-			_ => {
-				println! ("Don't know how to handle this message, ignoring");
-				continue;
-			},
-		};
-		
-		let resp = match req {
-			Message::Request1 {
-				mac: None,
-				idem_id,
-			} => {
-				if recent_idem_ids.contains (&idem_id) {
-					println! ("Ignoring request we already processed");
-					None
-				}
-				else {
-					recent_idem_ids.insert (0, idem_id);
-					recent_idem_ids.truncate (30);
-					Some (vec! [
-						Message::Response1 (our_mac),
-						Message::Response2 (message::Response2 {
-							idem_id,
-							nickname: nickname.clone (),
-						}),
-					])
-				}
-			},
-			_ => continue,
-		};
-		
-		if let Some (resp) = resp {
-			socket.send_to (&Message::many_to_vec (&resp)?, remote_addr).unwrap ();
-		}
-	}
-}
-
-fn recv_msg_from (socket: &UdpSocket) -> Result <(Vec <Message>, SocketAddr), AppError> 
-{
-	let mut buf = vec! [0u8; PACKET_SIZE];
-	let (bytes_recved, remote_addr) = socket.recv_from (&mut buf)?;
-	buf.truncate (bytes_recved);
-	let msgs = Message::from_slice2 (&buf)?;
-	
-	Ok ((msgs, remote_addr))
-}

src/message.rs

@@ -19,10 +19,10 @@ pub enum Message {
 	// 1
 	Request1 {
 		idem_id: [u8; 8],
-		mac: Option <[u8; 6]>
+		mac: Option <Mac>
 	},
 	// 2
-	Response1 (Option <[u8; 6]>),
+	Response1 (Option <Mac>),
 	// 3
 	Response2 (Response2),
 }
@@ -66,7 +66,7 @@ impl Write for DummyWriter {
 }
 
 impl Message {
-	pub fn write <T> (&self, w: &mut Cursor <T>) -> Result <(), std::io::Error> 
+	pub fn write <T> (&self, w: &mut Cursor <T>) -> Result <(), MessageError> 
 	where Cursor <T>: Write
 	{
 		match self {
@@ -92,7 +92,7 @@ impl Message {
 				Self::write_response_2 (&mut dummy_writer, x)?;
 				
 				// Write length and real params to real output
-				let len = u32::try_from (dummy_writer.position).unwrap ();
+				let len = u32::try_from (dummy_writer.position)?;
 				w.write_all (&len.to_le_bytes ())?;
 				Self::write_response_2 (w, x)?;
 			},
@@ -102,13 +102,11 @@ impl Message {
 	}
 	
 	fn write_response_2 <W: Write> (w: &mut W, params: &Response2) 
-	-> Result <(), std::io::Error>
+	-> Result <(), MessageError>
 	{
 		w.write_all (&params.idem_id)?;
 		let nickname = params.nickname.as_bytes ();
-		let nickname_len = u32::try_from (nickname.len ()).unwrap ();
+		tlv::Writer::<_>::lv_bytes (w, nickname)?;
-		w.write_all (&nickname_len.to_le_bytes ())?;
-		w.write_all (&nickname)?;
 		Ok (())
 	}
 	
@@ -124,14 +122,14 @@ impl Message {
 		Ok (())
 	}
 	
-	pub fn to_vec (&self) -> Result <Vec <u8>, tlv::TlvError> {
+	pub fn to_vec (&self) -> Result <Vec <u8>, MessageError> {
 		let mut cursor = Cursor::new (Vec::with_capacity (PACKET_SIZE));
 		cursor.write_all (&MAGIC_NUMBER)?;
 		self.write (&mut cursor)?;
 		Ok (cursor.into_inner ())
 	}
 	
-	pub fn many_to_vec (msgs: &[Self]) -> Result <Vec <u8>, tlv::TlvError> {
+	pub fn many_to_vec (msgs: &[Self]) -> Result <Vec <u8>, MessageError> {
 		let mut cursor = Cursor::new (Vec::with_capacity (PACKET_SIZE));
 		cursor.write_all (&MAGIC_NUMBER)?;
 		for msg in msgs {
@@ -140,28 +138,6 @@ impl Message {
 		Ok (cursor.into_inner ())
 	}
 	
-	fn read1 <R: std::io::Read> (r: &mut R) -> Result <Self, MessageError> {
-		let t = tlv::Reader::u8 (r)?;
-		
-		Ok (match t {
-			1 => {
-				let mut idem_id = [0u8; 8];
-				r.read_exact (&mut idem_id)?;
-				
-				let mac = Self::read_mac_opt (r)?;
-				Self::Request1 {
-					idem_id,
-					mac,
-				}
-			},
-			2 => {
-				let mac = Self::read_mac_opt (r)?;
-				Self::Response1 (mac)
-			},
-			_ => return Err (MessageError::UnknownType),
-		})
-	}
-	
 	fn read2 <R: std::io::Read> (r: &mut R) -> Result <Self, MessageError> {
 		let t = tlv::Reader::u8 (r)?;
 		
@@ -181,24 +157,12 @@ impl Message {
 				Self::Response1 (mac)
 			},
 			3 => {
-				let mut len = [0; 4];
+				tlv::Reader::<_>::length (r)?;
-				r.read_exact (&mut len)?;
-				let _len = len;
 				
 				let mut idem_id = [0; 8];
 				r.read_exact (&mut idem_id)?;
 				
-				let mut nickname_len = [0; 4];
+				let nickname = tlv::Reader::<_>::lv_bytes_to_vec (r, 64)?;
-				r.read_exact (&mut nickname_len)?;
-				let nickname_len = u32::from_le_bytes (nickname_len);
-				let nickname_len = usize::try_from (nickname_len)?;
-				
-				if nickname_len > 64 {
-					return Err (MessageError::LengthPrefixTooLong ((64, nickname_len)));
-				}
-				
-				let mut nickname = vec! [0u8; nickname_len];
-				r.read_exact (&mut nickname)?;
 				let nickname = String::from_utf8 (nickname)?;
 				
 				Self::Response2 (Response2 {
@@ -223,12 +187,6 @@ impl Message {
 		})
 	}
 	
-	pub fn from_slice1 (buf: &[u8]) -> Result <Self, MessageError> {
-		let mut cursor = Cursor::new (buf);
-		tlv::Reader::expect (&mut cursor, &MAGIC_NUMBER)?;
-		Self::read1 (&mut cursor)
-	}
-	
 	pub fn from_slice2 (buf: &[u8]) -> Result <Vec <Self>, MessageError> {
 		let mut cursor = Cursor::new (buf);
 		tlv::Reader::expect (&mut cursor, &MAGIC_NUMBER)?;
@@ -248,7 +206,7 @@ mod test {
 	use super::*;
 	
 	#[test]
-	fn test_write_2 () {
+	fn test_write_2 () -> Result <(), MessageError> {
 		for (input, expected) in [
 			(
 				vec! [
@@ -296,13 +254,15 @@ mod test {
 				],
 			),
 		] { 
-			let actual = Message::many_to_vec (&input).unwrap ();
+			let actual = Message::many_to_vec (&input)?;
 			assert_eq! (actual, expected, "{:?}", input);
 		}
+		
+		Ok (())
 	}
 	
 	#[test]
-	fn test_write_1 () {
+	fn test_write_1 () -> Result <(), MessageError> {
 		for (input, expected) in [
 			(
 				Message::Request1 {
@@ -344,13 +304,15 @@ mod test {
 				],
 			),
 		].into_iter () {
-			let actual = input.to_vec ().unwrap ();
+			let actual = input.to_vec ()?;
 			assert_eq! (actual, expected, "{:?}", input);
 		}
+		
+		Ok (())
 	}
 	
 	#[test]
-	fn test_read_2 () {
+	fn test_read_2 () -> Result <(), MessageError> {
 		for input in [
 			vec! [
 				Message::Request1 {
@@ -372,83 +334,11 @@ mod test {
 				}),
 			],
 		].into_iter () {
-			let encoded = Message::many_to_vec (&input).unwrap ();
+			let encoded = Message::many_to_vec (&input)?;
-			let decoded = Message::from_slice2 (&encoded).unwrap ();
+			let decoded = Message::from_slice2 (&encoded)?;
-			assert_eq! (input, decoded);
-		}
-	}
-	
-	#[test]
-	fn test_read_1 () {
-		for input in [
-			Message::Request1 {
-				idem_id: [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08],
-				mac: None,
-			},
-			Message::Response1 (Some ([0x11, 0x22, 0x33, 0x44, 0x55, 0x66])),
-			Message::Response1 (None),
-		].into_iter () {
-			let encoded = input.to_vec ().unwrap ();
-			let decoded = Message::from_slice1 (&encoded).unwrap ();
 			assert_eq! (input, decoded);
 		}
 		
-		for (expected, input) in [
+		Ok (())
-			(
-				Message::Request1 {
-					idem_id: [0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08],
-					mac: None,
-				},
-				vec! [
-					154, 74, 67, 129,
-					// Request tag
-					1,
-					// Idem ID
-					1, 2, 3, 4, 5, 6, 7, 8,
-					// MAC is None
-					0,
-				],
-			),
-			(
-				Message::Response1 (Some ([0x11, 0x22, 0x33, 0x44, 0x55, 0x66])), 
-				vec! [
-					// Magic number for LookAround packets
-					154, 74, 67, 129,
-					// Response tag
-					2, 
-					// MAC is Some
-					1,
-					// MAC
-					17, 34, 51, 68, 85, 102,
-				],
-			),
-			(
-				Message::Response1 (None), 
-				vec! [
-					// Magic number for LookAround packets
-					154, 74, 67, 129,
-					// Response tag
-					2, 
-					// MAC is None
-					0,
-				],
-			),
-			(
-				Message::Response1 (None), 
-				vec! [
-					// Magic number for LookAround packets
-					154, 74, 67, 129,
-					// Response tag
-					2, 
-					// MAC is None
-					0,
-					// New tag that older versions will just ignore
-					255,
-				],
-			),
-		].into_iter () {
-			let actual = Message::from_slice1 (&input).unwrap ();
-			assert_eq! (actual, expected, "{:?}", actual);
-		}
 	}
 }

src/prelude.rs

@@ -0,0 +1,38 @@
+pub use std::{
+	collections::HashMap,
+	env,
+	net::{
+		Ipv4Addr,
+		SocketAddr,
+		SocketAddrV4,
+	},
+	str::FromStr,
+	time::Duration,
+};
+
+pub use mac_address::{
+	MacAddress,
+	get_mac_address,
+};
+pub use tokio::{
+	net::UdpSocket,
+	time::{
+		sleep,
+		timeout,
+	},
+};
+
+pub use crate::{
+	app_common::{
+		self,
+		AppError,
+		CliArgError,
+		recv_msg_from,
+	},
+	ip::get_ips,
+	message::{
+		self,
+		PACKET_SIZE,
+		Message,
+	},
+};

src/server.rs

@@ -0,0 +1,133 @@
+use crate::prelude::*;
+
+#[derive (Clone)]
+struct Params {
+	common: app_common::Params,
+	bind_addrs: Vec <Ipv4Addr>,
+	nickname: String,
+	our_mac: Option <[u8; 6]>,
+}
+
+pub async fn server <I: Iterator <Item=String>> (args: I) -> Result <(), AppError> 
+{
+	let params = configure (args)?;
+	
+	// This was too hard to do in a functional style
+	let mut tasks = vec! [];
+	
+	for bind_addr in &params.bind_addrs {
+		let socket = match UdpSocket::bind (SocketAddrV4::new (Ipv4Addr::UNSPECIFIED, params.common.server_port)).await {
+			Err (e) => {
+				println! ("Error binding socket: {:?}", e);
+				continue;
+			},
+			Ok (x) => x,
+		};
+		
+		socket.join_multicast_v4 (params.common.multicast_addr, *bind_addr)?;
+		
+		dbg! (bind_addr);
+		
+		tasks.push (tokio::spawn (serve_interface (params.clone (), socket)));
+	}
+	
+	for task in tasks {
+		task.await??;
+	}
+	
+	Ok (())
+}
+
+fn configure <I: Iterator <Item=String>> (mut args: I) -> Result <Params, AppError>
+{
+	let common = app_common::Params::default ();
+	let mut bind_addrs = vec![];
+	let mut nickname = String::new ();
+	
+	while let Some (arg) = args.next () {
+		match arg.as_str () {
+			"--bind-addr" => {
+				bind_addrs.push (match args.next () {
+					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
+					Some (x) => Ipv4Addr::from_str (&x)?,
+				});
+			},
+			"--nickname" => {
+				nickname = match args.next () {
+					None => return Err (CliArgError::MissingArgumentValue (arg).into ()),
+					Some (x) => x
+				};
+			},
+			_ => return Err (CliArgError::UnrecognizedArgument (arg).into ()),
+		}
+	}
+	
+	let our_mac = get_mac_address ()?.map (|x| x.bytes ());
+	if our_mac.is_none () {
+		println! ("Warning: Can't find our own MAC address. We won't be able to respond to MAC-specific lookaround requests");
+	}
+	
+	if bind_addrs.is_empty () {
+		println! ("No bind addresses found, auto-detecting all local IPs");
+		bind_addrs = get_ips ()?;
+	}
+	
+	Ok (Params {
+		common,
+		bind_addrs,
+		nickname,
+		our_mac,
+	})
+}
+
+async fn serve_interface (params: Params, socket: UdpSocket) 
+-> Result <(), AppError>
+{
+	let mut recent_idem_ids = Vec::with_capacity (32);
+	
+	loop {
+		println! ("Listening...");
+		let (req_msgs, remote_addr) = match recv_msg_from (&socket).await {
+			Ok (x) => x,
+			Err (e) => {
+				println! ("Error while receiving message: {:?}", e);
+				continue;
+			},
+		};
+		
+		let req = match req_msgs.into_iter ().next () {
+			Some (x) => x,
+			_ => {
+				println! ("Don't know how to handle this message, ignoring");
+				continue;
+			},
+		};
+		
+		let resp = match req {
+			Message::Request1 {
+				mac: None,
+				idem_id,
+			} => {
+				if recent_idem_ids.contains (&idem_id) {
+					None
+				}
+				else {
+					recent_idem_ids.insert (0, idem_id);
+					recent_idem_ids.truncate (30);
+					Some (vec! [
+						Message::Response1 (params.our_mac),
+						Message::Response2 (message::Response2 {
+							idem_id,
+							nickname: params.nickname.clone (),
+						}),
+					])
+				}
+			},
+			_ => continue,
+		};
+		
+		if let Some (resp) = resp {
+			socket.send_to (&Message::many_to_vec (&resp)?, remote_addr).await?;
+		}
+	}
+}

src/tlv.rs

@@ -6,8 +6,14 @@ type Result <T> = std::result::Result <T, TlvError>;
 pub enum TlvError {
 	#[error ("Buffer too big")]
 	BufferTooBig,
-	#[error ("Caller-provided buffer too small")]
+	
-	CallerBufferTooSmall,
+	// Violets are purple,
+	// To live is to suffer,
+	// The data is too big,
+	// For the gosh-darn buffer.
+	
+	#[error ("Data too big")]
+	DataTooBig,
 	#[error (transparent)]
 	Io (#[from] std::io::Error),
 	#[error ("Actual bytes didn't match expected bytes")]
@@ -54,22 +60,24 @@ impl <R: std::io::Read> Reader <R> {
 		Ok (())
 	}
 	
-	fn length (r: &mut R) -> Result <u32> {
+	pub fn length (r: &mut R) -> Result <u32> {
 		let mut buf = [0; 4];
 		r.read_exact (&mut buf)?;
 		
 		Ok (u32::from_le_bytes (buf))
 	}
 	
-	pub fn lv_bytes (r: &mut R, buf: &mut [u8]) -> Result <u32> {
+	pub fn lv_bytes_to_vec (r: &mut R, limit: usize) -> Result <Vec <u8>> {
 		let l = Self::length (r)?;
-		if usize::try_from (l)? > buf.len () {
+		let l = usize::try_from (l)?;
-			return Err (TlvError::CallerBufferTooSmall);
+		if l > limit {
+			return Err (TlvError::DataTooBig);
 		}
 		
-		r.read_exact (&mut buf [0..usize::try_from (l)?])?;
+		let mut v = vec! [0u8; l];
+		r.read_exact (&mut v)?;
 		
-		Ok (l)
+		Ok (v)
 	}
 	
 	pub fn u8 (r: &mut R) -> std::io::Result <u8> {
@@ -82,15 +90,17 @@ impl <R: std::io::Read> Reader <R> {
 
 #[cfg (test)]
 mod test {
+	use super::*;
+	
 	#[test]
-	fn test_1 () {
+	fn test_1 () -> Result <()> {
 		use std::io::Cursor;
 		
 		let b = "hi there".as_bytes ();
 		
 		let mut w = Cursor::new (Vec::default ());
 		
-		super::Writer::lv_bytes (&mut w, b).unwrap ();
+		super::Writer::lv_bytes (&mut w, b)?;
 		
 		let v = w.into_inner ();
 		
@@ -102,11 +112,11 @@ mod test {
 		
 		let mut r = Cursor::new (v);
 		
-		let mut buf = vec! [0; 1024];
+		let buf = Reader::lv_bytes_to_vec (&mut r, 1024)?;
 		
-		let bytes_read = super::Reader::lv_bytes (&mut r, &mut buf).unwrap ();
+		assert_eq! (buf.len (), b.len ());
+		assert_eq! (b, &buf);
 		
-		assert_eq! (usize::try_from (bytes_read).unwrap (), b.len ());
+		Ok (())
-		assert_eq! (b, &buf [0..usize::try_from (bytes_read).unwrap ()]);
 	}
 }