1 files changed, 100 insertions, 0 deletions
diff --git a/examples/dgram.rs b/examples/dgram.rs
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+++ b/examples/dgram.rs
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+//! Datagram transport example (equivalent to example4.cpp).
+//!
+//! Creates two nodes and sends datagrams between them
+//! using the dgram callback API.
+//!
+//! Usage:
+//!   cargo run --example dgram
+
+use std::sync::{Arc, Mutex};
+use std::time::Duration;
+use tesseras_dht::Node;
+use tesseras_dht::id::NodeId;
+use tesseras_dht::nat::NatState;
+
+fn main() {
+    env_logger::Builder::from_env(
+        env_logger::Env::default().default_filter_or("info"),
+    )
+    .format(|buf, record| {
+        use std::io::Write;
+        writeln!(
+            buf,
+            "{} [{}] {}",
+            record.level(),
+            record.target(),
+            record.args()
+        )
+    })
+    .init();
+
+    let mut node1 = Node::bind(0).expect("bind node1");
+    node1.set_nat_state(NatState::Global);
+    let addr1 = node1.local_addr().unwrap();
+    let id1 = *node1.id();
+
+    let mut node2 = Node::bind(0).expect("bind node2");
+    node2.set_nat_state(NatState::Global);
+    let addr2 = node2.local_addr().unwrap();
+    let id2 = *node2.id();
+
+    println!("Node 1: {} @ {addr1}", node1.id_hex());
+    println!("Node 2: {} @ {addr2}", node2.id_hex());
+
+    // Join node2 to node1
+    node2.join("127.0.0.1", addr1.port()).expect("join");
+
+    // Poll to establish routing
+    for _ in 0..10 {
+        node1.poll().ok();
+        node2.poll().ok();
+        std::thread::sleep(Duration::from_millis(50));
+    }
+
+    // Set up dgram callbacks
+    let received1: Arc<Mutex<Vec<String>>> = Arc::new(Mutex::new(Vec::new()));
+    let received2: Arc<Mutex<Vec<String>>> = Arc::new(Mutex::new(Vec::new()));
+
+    let r1 = received1.clone();
+    node1.set_dgram_callback(move |data: &[u8], from: &NodeId| {
+        let msg = String::from_utf8_lossy(data).to_string();
+        println!("Node 1 received: '{msg}' from {from:?}");
+        r1.lock().unwrap().push(msg);
+    });
+
+    let r2 = received2.clone();
+    node2.set_dgram_callback(move |data: &[u8], from: &NodeId| {
+        let msg = String::from_utf8_lossy(data).to_string();
+        println!("Node 2 received: '{msg}' from {from:?}");
+        r2.lock().unwrap().push(msg);
+    });
+
+    // Send datagrams
+    println!("\n--- Sending datagrams ---");
+    node1.send_dgram(b"hello from node1", &id2);
+    node2.send_dgram(b"hello from node2", &id1);
+
+    // Poll to deliver
+    for _ in 0..10 {
+        node1.poll().ok();
+        node2.poll().ok();
+        std::thread::sleep(Duration::from_millis(50));
+    }
+
+    // Note: actual dgram delivery requires the full
+    // send queue → address resolution → send flow.
+    // This example demonstrates the API; full delivery
+    // is wired in integration.
+
+    println!("\n--- Summary ---");
+    println!(
+        "Node 1 received {} messages",
+        received1.lock().unwrap().len()
+    );
+    println!(
+        "Node 2 received {} messages",
+        received2.lock().unwrap().len()
+    );
+    println!("Node 1 send queue pending: queued for delivery");
+    println!("Node 2 send queue pending: queued for delivery");
+}