Revert "refactor(iroh-net): remove random choice of direct addr (#2509)"

This reverts commit c1c3539.

Author: Arqu

iroh-net/src/magicsock.rs

@@ -499,7 +499,10 @@ impl MagicSock {
         let dest = QuicMappedAddr(dest);
 
         let mut transmits_sent = 0;
-        match self.node_map.get_send_addrs(dest) {
+        match self
+            .node_map
+            .get_send_addrs(dest, self.ipv6_reported.load(Ordering::Relaxed))
+        {
             Some((public_key, udp_addr, relay_url, mut msgs)) => {
                 let mut pings_sent = false;
                 // If we have pings to send, we *have* to send them out first.
@@ -3012,7 +3015,7 @@ mod tests {
     #[tokio::test(flavor = "multi_thread")]
     async fn test_two_devices_roundtrip_network_change() -> Result<()> {
         time::timeout(
-            Duration::from_secs(90),
+            Duration::from_secs(50),
             test_two_devices_roundtrip_network_change_impl(),
         )
         .await?

iroh-net/src/magicsock/node_map.rs

@@ -186,6 +186,7 @@ impl NodeMap {
     pub(super) fn get_send_addrs(
         &self,
         addr: QuicMappedAddr,
+        have_ipv6: bool,
     ) -> Option<(
         PublicKey,
         Option<SocketAddr>,
@@ -195,7 +196,7 @@ impl NodeMap {
         let mut inner = self.inner.lock();
         let ep = inner.get_mut(NodeStateKey::QuicMappedAddr(addr))?;
         let public_key = *ep.public_key();
-        let (udp_addr, relay_url, msgs) = ep.get_send_addrs();
+        let (udp_addr, relay_url, msgs) = ep.get_send_addrs(have_ipv6);
         Some((public_key, udp_addr, relay_url, msgs))
     }
 

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

@@ -6,6 +6,7 @@ use std::{
 };
 
 use iroh_metrics::inc;
+use rand::seq::IteratorRandom;
 use serde::{Deserialize, Serialize};
 use tokio::sync::mpsc;
 use tracing::{debug, event, info, instrument, trace, warn, Level};
@@ -260,8 +261,12 @@ impl NodeState {
 
     /// Returns the address(es) that should be used for sending the next packet.
     ///
-    /// This may return to send on one, both or no paths.
-    fn addr_for_send(&mut self, now: &Instant) -> (Option<SocketAddr>, Option<RelayUrl>) {
+    /// Any or all of the UDP and relay addrs may be non-zero.
+    fn addr_for_send(
+        &mut self,
+        now: &Instant,
+        have_ipv6: bool,
+    ) -> (Option<SocketAddr>, Option<RelayUrl>) {
         if relay_only_mode() {
             debug!("in `DEV_relay_ONLY` mode, giving the relay address as the only viable address for this endpoint");
             return (None, self.relay_url());
@@ -285,8 +290,20 @@ impl NodeState {
                 (Some(best_addr.addr), self.relay_url())
             }
             best_addr::State::Empty => {
-                trace!("best_addr is unset, use relay");
-                (None, self.relay_url())
+                // No direct connection has been used before.  If we know of any possible
+                // candidate addresses, randomly try to use one while also sending via relay
+                // at the same time.
+                let addr = self
+                    .direct_addr_state
+                    .keys()
+                    .filter(|ipp| match ipp.ip() {
+                        IpAddr::V4(_) => true,
+                        IpAddr::V6(_) => have_ipv6,
+                    })
+                    .choose_stable(&mut rand::thread_rng())
+                    .map(|ipp| SocketAddr::from(*ipp));
+                trace!(udp_addr = ?addr, "best_addr is unset, use candidate addr and relay");
+                (addr, self.relay_url())
             }
         };
         let typ = match (best_addr, relay_url.clone()) {
@@ -1089,10 +1106,11 @@ impl NodeState {
     #[instrument("get_send_addrs", skip_all, fields(node = %self.node_id.fmt_short()))]
     pub(crate) fn get_send_addrs(
         &mut self,
+        have_ipv6: bool,
     ) -> (Option<SocketAddr>, Option<RelayUrl>, Vec<PingAction>) {
         let now = Instant::now();
         self.last_used.replace(now);
-        let (udp_addr, relay_url) = self.addr_for_send(&now);
+        let (udp_addr, relay_url) = self.addr_for_send(&now, have_ipv6);
         let mut ping_msgs = Vec::new();
 
         if self.want_call_me_maybe(&now) {

iroh/tests/sync.rs

@@ -243,7 +243,6 @@ async fn sync_gossip_bulk() -> Result<()> {
 
 /// This tests basic sync and gossip with 3 peers.
 #[tokio::test]
-#[ignore = "flaky"]
 async fn sync_full_basic() -> Result<()> {
     let mut rng = test_rng(b"sync_full_basic");
     setup_logging();