From 40b890bc13808fa9977f6c25575a167d580099df Mon Sep 17 00:00:00 2001
From: Jacob Kiers <code@kiers.eu>
Date: Fri, 25 Aug 2023 22:54:41 +0200
Subject: [PATCH] Add much better debug logging of address resolution

Signed-off-by: Jacob Kiers <code@kiers.eu>
---
 src/servers/upstream_address.rs | 33 ++++++++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/src/servers/upstream_address.rs b/src/servers/upstream_address.rs
index 4c34dbf..5b07e04 100644
--- a/src/servers/upstream_address.rs
+++ b/src/servers/upstream_address.rs
@@ -51,20 +51,24 @@ impl UpstreamAddress {
     pub async fn resolve(&mut self, mode: ResolutionMode) -> Result<Vec<SocketAddr>> {
         if self.is_resolved() && self.is_valid() {
             debug!(
-                "Already got address {:?}, still valid for {}",
+                "Already got address {:?}, still valid for {:.3}s",
                 &self.resolved_addresses,
-                self.time_remaining()
+                self.time_remaining().as_seconds_f64()
             );
             return Ok(self.resolved_addresses.clone());
         }
 
-        debug!("Resolving addresses for {}", &self.address);
+        debug!(
+            "Resolving addresses for {} with mode {:?}",
+            &self.address, &mode
+        );
 
         let lookup_result = tokio::net::lookup_host(&self.address).await;
 
-        let resolved_addresses = match lookup_result {
-            Ok(resolved_addresses) => resolved_addresses,
+        let resolved_addresses: Vec<SocketAddr> = match lookup_result {
+            Ok(resolved_addresses) => resolved_addresses.into_iter().collect(),
             Err(e) => {
+                debug!("Failed looking up {}: {}", &self.address, &e);
                 // Protect against DNS flooding. Cache the result for 1 second.
                 self.resolved_time = Some(Instant::now());
                 self.ttl = Some(Duration::seconds(3));
@@ -72,6 +76,8 @@ impl UpstreamAddress {
             }
         };
 
+        debug!("Resolved addresses: {:?}", &resolved_addresses);
+
         let addresses: Vec<SocketAddr> = match mode {
             ResolutionMode::Ipv4 => resolved_addresses
                 .into_iter()
@@ -83,10 +89,13 @@ impl UpstreamAddress {
                 .filter(|a| a.is_ipv6())
                 .collect(),
 
-            _ => resolved_addresses.collect(),
+            _ => resolved_addresses,
         };
 
-        debug!("Got addresses for {}: {:?}", &self.address, &addresses);
+        debug!(
+            "Got {} addresses for {}: {:?}",
+            &mode, &self.address, &addresses
+        );
         debug!(
             "Resolved at {}",
             OffsetDateTime::now_utc()
@@ -120,3 +129,13 @@ impl From<&str> for ResolutionMode {
         }
     }
 }
+
+impl Display for ResolutionMode {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        match self {
+            ResolutionMode::Ipv4 => write!(f, "IPv4Only"),
+            ResolutionMode::Ipv6 => write!(f, "IPv6Only"),
+            ResolutionMode::Ipv4AndIpv6 => write!(f, "IPv4 and IPv6"),
+        }
+    }
+}