Stop panicking on shutdown in the syncer and network init (#7104)

zebra-network/src/meta_addr/peer_addr.rs

@@ -3,7 +3,7 @@
 
 use std::{
     fmt,
-    net::SocketAddr,
+    net::{Ipv4Addr, SocketAddr},
     ops::{Deref, DerefMut},
     str::FromStr,
 };
@@ -66,6 +66,11 @@ impl DerefMut for PeerSocketAddr {
 }
 
 impl PeerSocketAddr {
+    /// Returns an unspecified `PeerSocketAddr`, which can't be used for outbound connections.
+    pub fn unspecified() -> Self {
+        Self(SocketAddr::new(Ipv4Addr::UNSPECIFIED.into(), 0))
+    }
+
     /// Return the underlying [`SocketAddr`], which allows sensitive peer address information to
     /// be printed and logged.
     pub fn remove_socket_addr_privacy(&self) -> SocketAddr {

zebra-network/src/peer_set/initialize.rs

@@ -213,7 +213,17 @@ where
     // Wait for the initial seed peer count
     let mut active_outbound_connections = initial_peers_join
         .await
-        .expect("unexpected panic in spawned initial peers task")
+        .unwrap_or_else(|e @ JoinError { .. }| {
+            if e.is_panic() {
+                panic!("panic in initial peer connections task: {e:?}");
+            } else {
+                info!(
+                    "task error during initial peer connections: {e:?},\
+                     is Zebra shutting down?"
+                );
+                Err(e.into())
+            }
+        })
         .expect("unexpected error connecting to initial peers");
     let active_initial_peer_count = active_outbound_connections.update_count();
 
@@ -353,8 +363,18 @@ where
         .collect();
 
     while let Some(handshake_result) = handshakes.next().await {
-        let handshake_result =
+        let handshake_result = handshake_result.unwrap_or_else(|e @ JoinError { .. }| {
-            handshake_result.expect("unexpected panic in initial peer handshake");
+            if e.is_panic() {
+                panic!("panic in initial peer connection: {e:?}");
+            } else {
+                info!(
+                    "task error during initial peer connection: {e:?},\
+                     is Zebra shutting down?"
+                );
+                // Fake the address, it doesn't matter because we're shutting down anyway
+                Err((PeerSocketAddr::unspecified(), e.into()))
+            }
+        });
         match handshake_result {
             Ok(change) => {
                 handshake_success_total += 1;

zebrad/src/components/sync.rs

@@ -8,7 +8,7 @@ use color_eyre::eyre::{eyre, Report};
 use futures::stream::{FuturesUnordered, StreamExt};
 use indexmap::IndexSet;
 use serde::{Deserialize, Serialize};
-use tokio::{sync::watch, time::sleep};
+use tokio::{sync::watch, task::JoinError, time::sleep};
 use tower::{
     builder::ServiceBuilder, hedge::Hedge, limit::ConcurrencyLimit, retry::Retry, timeout::Timeout,
     Service, ServiceExt,
@@ -668,7 +668,17 @@ where
         let mut download_set = IndexSet::new();
         while let Some(res) = requests.next().await {
             match res
-                .expect("panic in spawned obtain tips request")
+                .unwrap_or_else(|e @ JoinError { .. }| {
+                    if e.is_panic() {
+                        panic!("panic in obtain tips task: {e:?}");
+                    } else {
+                        info!(
+                            "task error during obtain tips task: {e:?},\
+                     is Zebra shutting down?"
+                        );
+                        Err(e.into())
+                    }
+                })
                 .map_err::<Report, _>(|e| eyre!(e))
             {
                 Ok(zn::Response::BlockHashes(hashes)) => {