Remove 'udp_target' argument from wireguard-proxy, set it dynamically from first UDP packet recieved

src/bin/udp-test.rs

@@ -70,10 +70,10 @@ impl Server {
 fn main() {
     let raw_args = env::args().collect();
     let args = Args::new(&raw_args);
-    let mut first_arg = args.get_str(1, "127.0.0.1:51821");
+    let mut first_arg = args.get_str(1, "127.0.0.1:51820");
     if first_arg.contains("-h") {
         println!(
-            "usage: {} [-h] [-s run a self test through proxy/proxyd] [-is run a self test through proxy/proxyd without spawning other processes] [udp_host, 127.0.0.1:51821] [udp_target, 127.0.0.1:51821] [socket_timeout, 10]",
+            "usage: {} [-h] [-s run a self test through proxy/proxyd] [-is run a self test through proxy/proxyd without spawning other processes] [udp_host, 127.0.0.1:51820] [udp_target, 127.0.0.1:51820] [socket_timeout, 10]",
             args.get_str(0, "udp-test")
         );
         return;
@@ -148,16 +148,14 @@ fn main() {
         thread::sleep(sleep);
 
         let proxy_client = ProxyClient::new(
-            "127.0.0.1:51821".to_owned(),
             "127.0.0.1:51820".to_owned(),
             tcp_host.to_owned().to_owned(),
             15,
         );
 
         println!(
-            "udp_host: {}, udp_target: {}, tcp_target: {}, socket_timeout: {:?}",
+            "udp_host: {}, tcp_target: {}, socket_timeout: {:?}",
             proxy_client.udp_host,
-            proxy_client.udp_target,
             proxy_client.tcp_target,
             proxy_client.socket_timeout,
         );
@@ -172,7 +170,7 @@ fn main() {
 
     let server = Server::new(
         first_arg.to_owned(),
-        args.get_str(2, "127.0.0.1:51821").to_owned(),
+        args.get_str(2, "127.0.0.1:51820").to_owned(),
         args.get(3, 10),
     );
 

src/bin/wireguard-proxy.rs

@@ -6,23 +6,21 @@ fn main() {
     let args = Args::new(&raw_args);
     if args.get_str(1, "").contains("-h") {
         println!(
-            "usage: {} [-h] [udp_host, 127.0.0.1:51821] [udp_target, 127.0.0.1:51820] [tcp_target, 127.0.0.1:5555] [socket_timeout, 0]",
+            "usage: {} [-h] [udp_host, 127.0.0.1:51820] [tcp_target, 127.0.0.1:5555] [socket_timeout, 0]",
             args.get_str(0, "wireguard-proxy")
         );
         return;
     }
 
     let proxy_client = ProxyClient::new(
-        args.get_str(1, "127.0.0.1:51821").to_owned(),
-        args.get_str(2, "127.0.0.1:51820").to_owned(),
-        args.get_str(3, "127.0.0.1:5555").to_owned(),
-        args.get(4, 0),
+        args.get_str(1, "127.0.0.1:51820").to_owned(),
+        args.get_str(2, "127.0.0.1:5555").to_owned(),
+        args.get(3, 0),
     );
 
     println!(
-        "udp_host: {}, udp_target: {}, tcp_target: {}, socket_timeout: {:?}",
+        "udp_host: {}, tcp_target: {}, socket_timeout: {:?}",
         proxy_client.udp_host,
-        proxy_client.udp_target,
         proxy_client.tcp_target,
         proxy_client.socket_timeout,
     );

src/lib.rs

@@ -52,8 +52,21 @@ impl TcpUdpPipe {
         ))
     }
 
+    pub fn udp_to_tcp_connect_socket(&mut self) -> std::io::Result<usize> {
+        let (len, src_addr) = self.udp_socket.recv_from(&mut self.buf[2..])?;
+
+        println!("first packet from {}, connecting to that", src_addr);
+        self.udp_socket.connect(src_addr)?;
+
+        self.send_udp(len)
+    }
+
     pub fn udp_to_tcp(&mut self) -> std::io::Result<usize> {
         let len = self.udp_socket.recv(&mut self.buf[2..])?;
+        self.send_udp(len)
+    }
+
+    fn send_udp(&mut self, len: usize) -> std::io::Result<usize> {
         println!("udp got len: {}", len);
 
         self.buf[0] = ((len >> 8) & 0xFF) as u8;
@@ -80,16 +93,14 @@ impl TcpUdpPipe {
 
 pub struct ProxyClient {
     pub udp_host: String,
-    pub udp_target: String,
     pub tcp_target: String,
     pub socket_timeout: Option<Duration>,
 }
 
 impl ProxyClient {
-    pub fn new(udp_host: String, udp_target: String, tcp_target: String, secs: u64) -> ProxyClient {
+    pub fn new(udp_host: String, tcp_target: String, secs: u64) -> ProxyClient {
         ProxyClient {
             udp_host,
-            udp_target,
             tcp_target,
             socket_timeout: match secs {
                 0 => None,
@@ -105,9 +116,12 @@ impl ProxyClient {
 
         let udp_socket = UdpSocket::bind(&self.udp_host)?;
         udp_socket.set_read_timeout(self.socket_timeout)?;
-        //udp_socket.connect(&self.udp_target)?; // this isn't strictly needed...  just filters who we can receive from
 
         let mut udp_pipe = TcpUdpPipe::new(tcp_stream, udp_socket);
+
+        // we want to wait for first udp packet from client first, to set the target to respond to
+        udp_pipe.udp_to_tcp_connect_socket()?;
+
         let mut udp_pipe_clone = udp_pipe.try_clone()?;
         thread::spawn(move || loop {
             udp_pipe_clone