feat(core): do not crash the tracer for some socket errors (#1238)

crates/trippy-core/src/strategy.rs

@@ -1,13 +1,13 @@
 use self::state::TracerState;
 use crate::config::StrategyConfig;
-use crate::error::{Error, Result};
+use crate::error::{Error, IoError, Result};
 use crate::net::Network;
 use crate::probe::{
     ProbeStatus, Response, ResponseData, ResponseSeq, ResponseSeqIcmp, ResponseSeqTcp,
     ResponseSeqUdp,
 };
 use crate::types::{Checksum, Sequence, TimeToLive, TraceId};
-use crate::{Extensions, IcmpPacketType, MultipathStrategy, PortDirection, Protocol};
+use crate::{Extensions, IcmpPacketType, MultipathStrategy, PortDirection, Probe, Protocol};
 use std::net::IpAddr;
 use std::time::{Duration, SystemTime};
 use tracing::instrument;
@@ -99,16 +99,20 @@ impl<F: Fn(&Round<'_>)> Strategy<F> {
             let sent = SystemTime::now();
             match self.config.protocol {
                 Protocol::Icmp => {
-                    network.send_probe(st.next_probe(sent))?;
+                    let probe = st.next_probe(sent);
+                    Self::do_send(network, st, probe)?;
+                }
+                Protocol::Udp => {
+                    let probe = st.next_probe(sent);
+                    Self::do_send(network, st, probe)?;
                 }
-                Protocol::Udp => network.send_probe(st.next_probe(sent))?,
                 Protocol::Tcp => {
                     let mut probe = if st.round_has_capacity() {
                         st.next_probe(sent)
                     } else {
                         return Err(Error::InsufficientCapacity);
                     };
-                    while let Err(err) = network.send_probe(probe) {
+                    while let Err(err) = Self::do_send(network, st, probe) {
                         match err {
                             Error::AddressInUse(_) => {
                                 if st.round_has_capacity() {
@@ -126,6 +130,23 @@ impl<F: Fn(&Round<'_>)> Strategy<F> {
         Ok(())
     }
 
+    /// Send the probe and handle errors.
+    ///
+    /// Some errors are transient and should not be considered fatal.  In these cases we mark the
+    /// probe as failed and continue.
+    fn do_send<N: Network>(network: &mut N, st: &mut TracerState, probe: Probe) -> Result<()> {
+        match network.send_probe(probe) {
+            Ok(()) => Ok(()),
+            Err(Error::IoError(
+                IoError::Bind(_, _) | IoError::Connect(_, _) | IoError::SendTo(_, _),
+            )) => {
+                st.fail_probe();
+                Ok(())
+            }
+            Err(err) => Err(err),
+        }
+    }
+
     /// Read and process the next incoming `ICMP` packet.
     ///
     /// We allow multiple probes to be in-flight at any time, and we cannot guarantee that responses