Add discover example to upnp

crates/upnp/examples/discover.rs

@@ -0,0 +1,35 @@
+use std::time::Duration;
+
+use librqbit_upnp::{discover_once, discover_services, SSDP_SEARCH_ROOT_ST};
+
+#[tokio::main]
+async fn main() -> anyhow::Result<()> {
+    tracing_subscriber::fmt().init();
+
+    let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel();
+    let (stx, mut srx) = tokio::sync::mpsc::unbounded_channel::<()>();
+
+    let f1 = async move { discover_once(&tx, SSDP_SEARCH_ROOT_ST, Duration::from_secs(10)).await };
+
+    let f2 = async move {
+        while let Some(r) = rx.recv().await {
+            let stx = stx.clone();
+            tokio::spawn(async move {
+                match discover_services(r.location.clone()).await {
+                    Ok(s) => {
+                        println!("{}: {s:#?}", r.location);
+                    }
+                    Err(e) => {
+                        tracing::error!(location=%r.location, "error discovering")
+                    }
+                }
+                drop(stx);
+            });
+        }
+    };
+
+    let f3 = async move { while (srx.recv().await).is_some() {} };
+
+    tokio::join!(f1, f2, f3);
+    Ok(())
+}