Add DNS example: hickory-proto over smolmix UDP

smolmix/examples/tunnel_dns.rs

@@ -0,0 +1,79 @@
+//! DNS lookup through the Nym mixnet using the Tunnel API.
+//!
+//! Resolves `example.com` via clearnet (hickory-resolver) and via the mixnet
+//! (raw UDP to 1.1.1.1:53), then compares resolved IPs and timing.
+//!
+//! Run with:
+//!   cargo run --example tunnel_dns
+
+use std::net::Ipv4Addr;
+
+use hickory_proto::op::{Message, Query};
+use hickory_proto::rr::{Name, RData, RecordType};
+use hickory_resolver::TokioResolver;
+use smolmix::{NetworkEnvironment, Tunnel};
+use tracing::info;
+
+type BoxError = Box<dyn std::error::Error + Send + Sync>;
+
+#[tokio::main]
+async fn main() -> Result<(), BoxError> {
+    smolmix::init_logging();
+
+    let domain = "example.com";
+
+    // --- Clearnet baseline via hickory-resolver ---
+    info!("Clearnet DNS lookup for '{domain}'...");
+    let resolver = TokioResolver::builder_tokio()?.build();
+    let clearnet_start = tokio::time::Instant::now();
+    let lookup = resolver.lookup_ip(domain).await?;
+    let clearnet_ips: Vec<Ipv4Addr> = lookup
+        .iter()
+        .filter_map(|ip| match ip {
+            std::net::IpAddr::V4(v4) => Some(v4),
+            _ => None,
+        })
+        .collect();
+    let clearnet_duration = clearnet_start.elapsed();
+    info!("Clearnet: {:?} in {:?}", clearnet_ips, clearnet_duration);
+
+    // --- Mixnet via tunnel UDP ---
+    let tunnel = Tunnel::new(NetworkEnvironment::Mainnet).await?;
+    let udp = tunnel.udp_socket().await?;
+
+    let mut query = Message::new();
+    query.set_recursion_desired(true);
+    query.add_query(Query::query(Name::from_ascii(domain)?, RecordType::A));
+    let query_bytes = query.to_vec()?;
+
+    let mixnet_start = tokio::time::Instant::now();
+    udp.send_to(&query_bytes, "1.1.1.1:53".parse()?).await?;
+
+    let mut buf = vec![0u8; 1500];
+    let (n, _from) = udp.recv_from(&mut buf).await?;
+    let mixnet_duration = mixnet_start.elapsed();
+
+    let response = Message::from_vec(&buf[..n])?;
+    let mixnet_ips: Vec<Ipv4Addr> = response
+        .answers()
+        .iter()
+        .filter_map(|r| match r.data() {
+            RData::A(a) => Some(a.0),
+            _ => None,
+        })
+        .collect();
+
+    // --- Compare ---
+    info!("=== Results ===");
+    info!("Clearnet: {:?} ({:?})", clearnet_ips, clearnet_duration);
+    info!("Mixnet:   {:?} ({:?})", mixnet_ips, mixnet_duration);
+
+    let ips_match = !mixnet_ips.is_empty() && mixnet_ips.iter().all(|ip| clearnet_ips.contains(ip));
+    info!("IPs match: {ips_match}");
+
+    let slowdown = mixnet_duration.as_millis() as f64 / clearnet_duration.as_millis().max(1) as f64;
+    info!("Slowdown:  {slowdown:.1}x");
+
+    tunnel.shutdown().await;
+    Ok(())
+}