fix(iroh-net): reconfirm best addr when receiving data on it (#2255)

When receiving data via UDP, we were not extending the validity of the
current `best_addr`. This would trigger expiry of the `best_addr`, even
though it was actively being used.

This fix, extends the validity, everytime we successfully receive a UDP
packet on the current `best_addr`.

Closes #2169

iroh-net/src/magicsock/node_map/best_addr.rs

@@ -39,6 +39,7 @@ impl BestAddrInner {
 pub(super) enum Source {
     ReceivedPong,
     BestCandidate,
+    Udp,
 }
 
 impl Source {
@@ -47,6 +48,7 @@ impl Source {
             Source::ReceivedPong => from + TRUST_UDP_ADDR_DURATION,
             // TODO: Fix time
             Source::BestCandidate => from + Duration::from_secs(60 * 60),
+            Source::Udp => from + TRUST_UDP_ADDR_DURATION,
         }
     }
 }
@@ -141,6 +143,16 @@ impl BestAddr {
         }
     }
 
+    /// Reset the expiry, if the passed in addr matches the currently used one.
+    pub fn reconfirm_if_used(&mut self, addr: SocketAddr, source: Source, confirmed_at: Instant) {
+        if let Some(state) = self.0.as_mut() {
+            if state.addr.addr == addr {
+                state.confirmed_at = confirmed_at;
+                state.trust_until = Some(source.trust_until(confirmed_at));
+            }
+        }
+    }
+
     fn insert(
         &mut self,
         addr: SocketAddr,

iroh-net/src/magicsock/node_map/node_state.rs

@@ -26,7 +26,7 @@ use crate::{
 
 use crate::magicsock::{metrics::Metrics as MagicsockMetrics, ActorMessage, QuicMappedAddr};
 
-use super::best_addr::{self, BestAddr, ClearReason};
+use super::best_addr::{self, BestAddr, ClearReason, Source};
 use super::IpPort;
 
 /// Number of addresses that are not active that we keep around per node.
@@ -967,6 +967,8 @@ impl NodeState {
         };
         state.last_payload_msg = Some(now);
         self.last_used = Some(now);
+        self.best_addr
+            .reconfirm_if_used(addr.into(), Source::Udp, now);
     }
 
     pub(super) fn receive_relay(&mut self, url: &RelayUrl, _src: &PublicKey, now: Instant) {