fix: Avoid spurious PMTUD resets (#2293)

* fix: Avoid suprious PMTUD resets Previously, after PMTUD had completed, we could end up restarting PMTUD when packet loss counters for packets larger than the current PMTU exceeded the limit. We're now making sure to not do that. * WIP * Nits * Update path.rs Co-authored-by: Martin Thomson <[email protected]> Signed-off-by: Lars Eggert <[email protected]> * Fix condition * Update neqo-transport/src/path.rs Co-authored-by: Max Inden <[email protected]> Signed-off-by: Lars Eggert <[email protected]> * Fixes and test refactoring * Update neqo-transport/src/pmtud.rs Co-authored-by: Max Inden <[email protected]> Signed-off-by: Lars Eggert <[email protected]> * Fixes --------- Signed-off-by: Lars Eggert <[email protected]> Co-authored-by: Martin Thomson <[email protected]> Co-authored-by: Max Inden <[email protected]>
mozilla · Feb 12, 2025 · 8e82a9e · 8e82a9e
1 parent 714e099
commit 8e82a9e
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Showing 3 changed files with 167 additions and 137 deletions.
diff --git a/neqo-transport/src/packet/mod.rs b/neqo-transport/src/packet/mod.rs
@@ -249,7 +249,7 @@ impl PacketBuilder {
         pmtud: &Pmtud,
     ) -> bool {
         if pmtud.needs_probe() {
-            debug_assert!(pmtud.probe_size() > profile.limit());
+            debug_assert!(pmtud.probe_size() >= profile.limit());
             self.limit = pmtud.probe_size() - aead_expansion;
             true
         } else {

diff --git a/neqo-transport/src/path.rs b/neqo-transport/src/path.rs
@@ -525,12 +525,18 @@ impl Path {
     ) -> Self {
         let iface_mtu = match mtu::interface_and_mtu(remote.ip()) {
             Ok((name, mtu)) => {
-                qdebug!("Outbound interface {name} has MTU {mtu}");
+                qdebug!(
+                    "Outbound interface {name} for destination {ip} has MTU {mtu}",
+                    ip = remote.ip()
+                );
                 stats.pmtud_iface_mtu = mtu;
                 Some(mtu)
             }
             Err(e) => {
-                qwarn!("Failed to determine outbound interface: {e}");
+                qwarn!(
+                    "Failed to determine outbound interface for destination {ip}: {e}",
+                    ip = remote.ip()
+                );
                 None
             }
         };