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fix(auto): skip VPN utun interfaces and backoff beacon TX failures #11

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fix(auto): skip VPN utun interfaces and backoff beacon TX failures #11

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183 changes: 154 additions & 29 deletions crates/rns-interface/src/auto.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@ pub const MULTI_IF_DEQUE_TTL: f64 = 0.75;
// Per-platform ignores: loopback, Apple AWDL, cellular RIL, VPN tunnels.

#[cfg(target_os = "macos")]
const IGNORED_IFACES: &[&str] = &["awdl0", "llw0", "lo0", "en5"];
const IGNORED_IFACES: &[&str] = &["awdl0", "llw0", "lo0", "en5", "ipsec0"];

#[cfg(target_os = "linux")]
const IGNORED_IFACES: &[&str] = &["lo"];
Expand Down Expand Up @@ -568,12 +568,33 @@ pub fn list_network_interfaces() -> Result<Vec<NetworkInterfaceInfo>, String> {
Ok(by_name.into_values().collect())
}

/// VPN/tunnel NICs that may enumerate link-local addresses but cannot TX IPv6
/// multicast beacons (macOS `utun*` often returns ENOBUFS / os error 55).
fn is_builtin_ignored_iface(iface_name: &str) -> bool {
if IGNORED_IFACES.contains(&iface_name) {
return true;
}
#[cfg(any(target_os = "macos", target_os = "ios"))]
{
if iface_name.starts_with("utun") || iface_name.starts_with("ipsec") {
return true;
}
}
#[cfg(target_os = "macos")]
{
if iface_name.starts_with("ppp") {
return true;
}
}
false
}

fn iface_passes_filters(
iface_name: &str,
devices: Option<&[String]>,
ignored_devices: &[String],
) -> bool {
if IGNORED_IFACES.contains(&iface_name) {
if is_builtin_ignored_iface(iface_name) {
return false;
}
if ignored_devices.iter().any(|n| n == iface_name) {
Expand All @@ -587,6 +608,33 @@ fn iface_passes_filters(
true
}

const BEACON_TX_MAX_BACKOFF_SECS: f64 = 60.0;

#[derive(Debug, Clone, Copy)]
struct BeaconIfaceTxState {
consecutive_failures: u32,
backoff_until: Option<Instant>,
logged_warn: bool,
}

impl Default for BeaconIfaceTxState {
fn default() -> Self {
Self {
consecutive_failures: 0,
backoff_until: None,
logged_warn: false,
}
}
}

fn beacon_tx_backoff_secs(consecutive_failures: u32) -> f64 {
if consecutive_failures == 0 {
return BEACON_INTERVAL;
}
let mult = 2f64.powi(consecutive_failures.saturating_sub(1).min(6) as i32);
(BEACON_INTERVAL * mult).min(BEACON_TX_MAX_BACKOFF_SECS)
}

/// Enumerate link-local IPv6 addresses, applying device/ignore filters.
/// Drops addresses with unresolvable scope id — `scope_id = 0` silently
/// routes via the default NIC, which is wrong on multi-homed hosts.
Expand Down Expand Up @@ -1143,6 +1191,7 @@ pub async fn spawn_auto_interface(
tokio::spawn(async move {
let mut interval =
tokio::time::interval(std::time::Duration::from_secs_f64(BEACON_INTERVAL));
let mut tx_states: HashMap<String, BeaconIfaceTxState> = HashMap::new();
#[cfg(feature = "mobile-throttle")]
let mut was_foreground = true;
#[cfg(not(feature = "mobile-throttle"))]
Expand All @@ -1169,40 +1218,94 @@ pub async fn spawn_auto_interface(
}
// Snapshot adopted set; jobs task may have replaced it on link flap.
let snapshot = { beacon_link_locals.lock().await.clone() };
let now = Instant::now();
for (_name, ll_addr, scope_id) in &snapshot {
let state = tx_states.entry(_name.clone()).or_default();
if state
.backoff_until
.is_some_and(|until| now < until)
{
continue;
}
let beacon = make_beacon(&group_id, ll_addr);
let dest = SocketAddrV6::new(mcast_group, disc_port, 0, *scope_id);
if let Err(e) = set_multicast_if_v6(disc_sock_send.as_ref(), *scope_id) {
tracing::warn!(
iface = %_name,
ll = %ll_addr,
scope_id,
error = %e,
raw_os_error = ?e.raw_os_error(),
"auto: failed to select multicast outbound interface"
);
if !state.logged_warn {
tracing::warn!(
iface = %_name,
ll = %ll_addr,
scope_id,
error = %e,
raw_os_error = ?e.raw_os_error(),
"auto: failed to select multicast outbound interface"
);
state.logged_warn = true;
} else {
tracing::debug!(
iface = %_name,
ll = %ll_addr,
scope_id,
error = %e,
raw_os_error = ?e.raw_os_error(),
"auto: failed to select multicast outbound interface"
);
}
}
let res = disc_sock_send.send_to(&beacon, dest).await;
match res {
Ok(n) => tracing::debug!(
iface = %_name,
ll = %ll_addr,
scope_id,
dst = %dest,
hash = %hex32(&beacon),
sent_bytes = n,
"auto-instr beacon TX"
),
Err(e) => tracing::warn!(
iface = %_name,
ll = %ll_addr,
scope_id,
dst = %dest,
hash = %hex32(&beacon),
error = %e,
raw_os_error = ?e.raw_os_error(),
"auto: beacon TX failed"
),
Ok(n) => {
tx_states.insert(
_name.clone(),
BeaconIfaceTxState {
consecutive_failures: 0,
backoff_until: None,
logged_warn: false,
},
);
tracing::debug!(
iface = %_name,
ll = %ll_addr,
scope_id,
dst = %dest,
hash = %hex32(&beacon),
sent_bytes = n,
"auto-instr beacon TX"
);
}
Err(e) => {
state.consecutive_failures = state.consecutive_failures.saturating_add(1);
let backoff_secs = beacon_tx_backoff_secs(state.consecutive_failures);
state.backoff_until =
Some(now + std::time::Duration::from_secs_f64(backoff_secs));
if !state.logged_warn {
tracing::warn!(
iface = %_name,
ll = %ll_addr,
scope_id,
dst = %dest,
hash = %hex32(&beacon),
error = %e,
raw_os_error = ?e.raw_os_error(),
backoff_secs,
consecutive_failures = state.consecutive_failures,
"auto: beacon TX failed"
);
state.logged_warn = true;
} else {
tracing::debug!(
iface = %_name,
ll = %ll_addr,
scope_id,
dst = %dest,
hash = %hex32(&beacon),
error = %e,
raw_os_error = ?e.raw_os_error(),
backoff_secs,
consecutive_failures = state.consecutive_failures,
"auto: beacon TX failed"
);
}
}
}
}
}
Expand Down Expand Up @@ -2093,4 +2196,26 @@ mod tests {
let expected = BEACON_INTERVAL * 3.25;
assert!((REVERSE_PEERING_INTERVAL - expected).abs() < 0.001);
}

#[test]
fn test_beacon_tx_backoff_caps_at_max() {
assert!((beacon_tx_backoff_secs(1) - BEACON_INTERVAL).abs() < 0.001);
assert!(beacon_tx_backoff_secs(10) <= BEACON_TX_MAX_BACKOFF_SECS);
}

#[test]
fn test_is_builtin_ignored_iface_utun_prefix() {
assert!(is_builtin_ignored_iface("utun0"));
assert!(is_builtin_ignored_iface("utun4"));
assert!(is_builtin_ignored_iface("ipsec0"));
#[cfg(target_os = "macos")]
assert!(is_builtin_ignored_iface("ppp0"));
assert!(!is_builtin_ignored_iface("en0"));
}

#[test]
fn test_iface_passes_filters_skips_utun() {
assert!(!iface_passes_filters("utun4", None, &[]));
assert!(iface_passes_filters("en0", None, &[]));
}
}