feat: implement ICMP pings

Cargo.toml

@@ -82,6 +82,7 @@ zeroize = "1.5"
 bao-tree = { version = "0.1.5", features = ["tokio_io"], default-features = false }
 range-collections = "0.4.0"
 async-lock = { git = "/~https://github.com/smol-rs/async-lock", branch = "notgull/block-lock" }
+surge-ping = "0.8.0"
 
 
 [target.'cfg(target_os = "linux")'.dependencies]

src/hp/netcheck.rs

@@ -60,12 +60,12 @@ const DEFAULT_ACTIVE_RETRANSMIT_TIME: Duration = Duration::from_millis(200);
 /// The retransmit interval used when netcheck first runs. We have no past context to work with,
 /// and we want answers relatively quickly, so it's biased slightly more aggressive than
 /// [`DEFAULT_ACTIVE_RETRANSMIT_TIME`]. A few extra packets at startup is fine.
-
 const DEFAULT_INITIAL_RETRANSMIT: Duration = Duration::from_millis(100);
 
 const FULL_REPORT_INTERVAL: Duration = Duration::from_secs(5 * 60);
 
 const ENOUGH_REGIONS: usize = 3;
+
 // Chosen semi-arbitrarily
 const CAPTIVE_PORTAL_DELAY: Duration = Duration::from_millis(200);
 
@@ -287,28 +287,28 @@ async fn check_captive_portal(dm: &DerpMap, preferred_derp: Option<usize>) -> Re
         .build()?;
 
     // Note: the set of valid characters in a challenge and the total
-    // length is limited; see isChallengeChar in cmd/derper for more
+    // length is limited; see is_challenge_char in bin/derper for more
     // details.
-    let chal = format!("ts_{}", node.host_name);
+    let challenge = format!("ts_{}", node.host_name);
 
     let res = client
         .request(
             reqwest::Method::GET,
             format!("http://{}/generate_204", node.host_name),
         )
-        .header("X-Tailscale-Challenge", &chal)
+        .header("X-Tailscale-Challenge", &challenge)
         .send()
         .await?;
 
-    let expected_response = format!("response {chal}");
+    let expected_response = format!("response {challenge}");
     let is_valid_response = res
         .headers()
         .get("X-Tailscale-Response")
         .map(|s| s.to_str().unwrap_or_default())
         == Some(&expected_response);
 
     info!(
-        "[v2] checkCaptivePortal url={} status_code={} valid_response={}",
+        "check_captive_portal url={} status_code={} valid_response={}",
         res.url(),
         res.status(),
         is_valid_response,
@@ -317,6 +317,7 @@ async fn check_captive_portal(dm: &DerpMap, preferred_derp: Option<usize>) -> Re
 
     Ok(has_captive)
 }
+
 async fn measure_icmp_latency(reg: &DerpRegion, p: &Pinger) -> Result<Duration> {
     if reg.nodes.is_empty() {
         anyhow::bail!(
@@ -337,7 +338,7 @@ async fn measure_icmp_latency(reg: &DerpRegion, p: &Pinger) -> Result<Duration>
 
     // Use the unique node.name field as the packet data to reduce the
     // likelihood that we get a mismatched echo response.
-    p.send(node_addr, node.name.as_bytes()).await
+    p.send(node_addr.ip(), node.name.as_bytes()).await
 }
 
 async fn get_node_addr(n: &DerpNode, proto: ProbeProto) -> Option<SocketAddr> {

src/hp/ping.rs

@@ -1,23 +1,109 @@
 //! Allows sending ICMP echo requests to a host in order to determine network latency.
-//!
-//! Based on /~https://github.com/tailscale/tailscale/blob/main/net/ping/ping.go.
 
-use std::{net::SocketAddr, sync::Arc, time::Duration};
+use std::{fmt::Debug, net::IpAddr, sync::Arc, time::Duration};
 
-use anyhow::Error;
+use anyhow::Result;
+use surge_ping::{Client, Config, IcmpPacket, PingIdentifier, PingSequence, ICMP};
+use tracing::debug;
 
 #[derive(Debug, Clone)]
 pub struct Pinger(Arc<Inner>);
 
-#[derive(Debug)]
-struct Inner {}
+impl Debug for Inner {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Inner").finish()
+    }
+}
+
+struct Inner {
+    client_v6: Client,
+    client_v4: Client,
+}
+
+const DEFAULT_TIMEOUT: Duration = Duration::from_secs(5);
 
 impl Pinger {
-    pub async fn new() -> Result<Self, Error> {
-        Ok(Self(Arc::new(Inner {})))
+    pub async fn new() -> Result<Self> {
+        let client_v4 = Client::new(&Config::builder().kind(ICMP::V4).build())?;
+        let client_v6 = Client::new(&Config::builder().kind(ICMP::V6).build())?;
+
+        Ok(Self(Arc::new(Inner {
+            client_v4,
+            client_v6,
+        })))
+    }
+
+    pub async fn send(&self, addr: IpAddr, data: &[u8]) -> Result<Duration> {
+        let client = match addr {
+            IpAddr::V4(_) => &self.0.client_v4,
+            IpAddr::V6(_) => &self.0.client_v6,
+        };
+        let mut pinger = client.pinger(addr, PingIdentifier(rand::random())).await;
+        pinger.timeout(DEFAULT_TIMEOUT);
+        match pinger.ping(PingSequence(0), data).await? {
+            (IcmpPacket::V4(packet), dur) => {
+                debug!(
+                    "{} bytes from {}: icmp_seq={} ttl={:?} time={:0.2?}",
+                    packet.get_size(),
+                    packet.get_source(),
+                    packet.get_sequence(),
+                    packet.get_ttl(),
+                    dur
+                );
+                Ok(dur)
+            }
+
+            (IcmpPacket::V6(packet), dur) => {
+                debug!(
+                    "{} bytes from {}: icmp_seq={} hlim={} time={:0.2?}",
+                    packet.get_size(),
+                    packet.get_source(),
+                    packet.get_sequence(),
+                    packet.get_max_hop_limit(),
+                    dur
+                );
+                Ok(dur)
+            }
+        }
     }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    use tracing_subscriber::{prelude::*, EnvFilter};
+
+    #[tokio::test]
+    async fn test_ping_google() -> Result<()> {
+        tracing_subscriber::registry()
+            .with(tracing_subscriber::fmt::layer().with_writer(std::io::stderr))
+            .with(EnvFilter::from_default_env())
+            .try_init()
+            .ok();
+
+        // Public DNS addrs from google based on
+        // https://developers.google.com/speed/public-dns/docs/using
+
+        let pinger = Pinger::new().await?;
+
+        // IPv4
+        let dur = pinger.send("8.8.8.8".parse()?, &[1u8; 8]).await?;
+        assert!(!dur.is_zero());
+
+        // IPv6
+        match pinger
+            .send("2001:4860:4860:0:0:0:0:8888".parse()?, &[1u8; 8])
+            .await
+        {
+            Ok(dur) => {
+                assert!(!dur.is_zero());
+            }
+            Err(err) => {
+                tracing::error!("IPv6 is not available: {:?}", err);
+            }
+        }
 
-    pub async fn send(&self, _addr: SocketAddr, _data: &[u8]) -> Result<Duration, Error> {
-        anyhow::bail!("icmp is not available yet");
+        Ok(())
     }
 }