From 33a0ab1503175a3391d90d1970ae304cd78d95c5 Mon Sep 17 00:00:00 2001
From: Nils Andreas Svee <me@lochnair.net>
Date: Thu, 24 Sep 2026 23:11:09 +0700
Subject: [PATCH] fix(probe): reject unsupported and undersized reflector sets

---
 src/main.rs         | 23 +++++++++++++++++++++++
 src/pinger.rs       | 22 +++++++++++-----------
 src/settings/mod.rs |  5 ++++-
 3 files changed, 38 insertions(+), 12 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 9cb7758..72b924a 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -191,6 +191,7 @@ fn restore_shaper<T: TrafficControlBackend>(
 fn setup_reflectors(settings: &Settings) -> anyhow::Result<ReflectorSetup> {
     let configured = settings.load_reflectors()?;
     let configured_count = configured.len();
+    let requested_count = settings.advanced_settings.num_reflectors as usize;
 
     let default_reflectors = [
         IpAddr::from_str("9.9.9.9")?,
@@ -201,6 +202,17 @@ fn setup_reflectors(settings: &Settings) -> anyhow::Result<ReflectorSetup> {
         IpAddr::from_str("94.140.14.14")?,
     ];
 
+    let available_count = if configured.is_empty() {
+        default_reflectors.len()
+    } else {
+        configured_count
+    };
+    if available_count < requested_count {
+        anyhow::bail!(
+            "only {available_count} reflectors available, fewer than the configured {requested_count}"
+        );
+    }
+
     let reselection_enabled = configured_count > settings.advanced_settings.num_reflectors as usize;
     let (peers, pool) = if reselection_enabled {
         (default_reflectors.to_vec(), configured)
@@ -512,6 +524,17 @@ mod tests {
         };
         let setup = setup_reflectors(&settings).unwrap();
         let configured = settings.load_reflectors().unwrap();
+        std::fs::write(
+            &path,
+            "reflector_ip,ip_version,description\n192.0.2.1,4,test\n192.0.2.2,4,test\n192.0.2.3,4,test\n192.0.2.4,4,test\n",
+        ).unwrap();
+        assert!(setup_reflectors(&settings).is_err());
+        std::fs::write(
+            &path,
+            "reflector_ip,ip_version,description\n2001:db8::1,6,test\n",
+        )
+        .unwrap();
+        assert!(setup_reflectors(&settings).is_err());
         std::fs::remove_file(path).unwrap();
         assert!(!setup.reselection_enabled);
         assert_eq!(*setup.peers.read().unwrap(), configured);
diff --git a/src/pinger.rs b/src/pinger.rs
index 2436c18..1efb5e6 100644
--- a/src/pinger.rs
+++ b/src/pinger.rs
@@ -14,7 +14,7 @@ use icmp_socket2::socket::IcmpSocket;
 use icmp_socket2::{IcmpSocket4, Icmpv4Packet};
 use log::{debug, info, warn};
 use std::collections::HashMap;
-use std::net::{IpAddr, Ipv4Addr};
+use std::net::IpAddr;
 use std::sync::atomic::Ordering;
 use std::sync::{Arc, Mutex, RwLock};
 use std::time::{Duration, Instant};
@@ -185,10 +185,15 @@ pub trait PingSender {
                 info!("Ping sender shutting down");
                 return Ok(());
             }
-            // Clone the reflectors vec and drop the read lock immediately —
-            // holding it for the entire tick would starve the reflector selector's write lock.
+            // Release the read lock before sending so reselection can update peers.
             let reflectors_unlocked = reflectors_lock.read_anyhow()?;
-            let reflectors = reflectors_unlocked.clone();
+            let reflectors: Vec<_> = reflectors_unlocked
+                .iter()
+                .filter_map(|reflector| match reflector {
+                    IpAddr::V4(addr) => Some(*addr),
+                    IpAddr::V6(_) => None,
+                })
+                .collect();
             drop(reflectors_unlocked);
 
             if reflectors.is_empty() {
@@ -202,15 +207,10 @@ pub trait PingSender {
 
             let sleep_duration = Duration::from_secs_f64(tick_interval / reflectors.len() as f64);
 
-            for reflector in reflectors.iter() {
-                let addr: Ipv4Addr = match reflector {
-                    IpAddr::V4(ipv4) => *ipv4,
-                    IpAddr::V6(_) => continue,
-                };
-
+            for &addr in &reflectors {
                 let (packet, originate_timestamp) = self.craft_packet(id, seq);
                 let sent_at = Instant::now();
-                let key = (*reflector, type_, seq);
+                let key = (IpAddr::V4(addr), type_, seq);
                 inflight.lock_anyhow()?.insert(
                     key,
                     InFlightProbe {
diff --git a/src/settings/mod.rs b/src/settings/mod.rs
index 15152e9..577ee55 100644
--- a/src/settings/mod.rs
+++ b/src/settings/mod.rs
@@ -192,7 +192,10 @@ impl Settings {
             })?;
 
             match (record.ip_version, record.reflector_ip) {
-                (4, IpAddr::V4(_)) | (6, IpAddr::V6(_)) => {}
+                (4, IpAddr::V4(_)) => {}
+                (6, address @ IpAddr::V6(_)) => {
+                    bail!("reflector {address} is IPv6; only IPv4 reflectors are supported");
+                }
                 (version, address) => {
                     bail!("reflector {address} has inconsistent IP version {version}");
                 }