From 7ddd0365b8b3d4e587c78103dc3d26e8cd888865 Mon Sep 17 00:00:00 2001
From: Andreas Rammhold <andreas@rammhold.de>
Date: Wed, 9 Nov 2022 00:27:19 +0100
Subject: [PATCH] Handle IPv6-only results even in GETHOSTBYNAME

Previously IPv6-only results would return an empty successful result
message. This doesn't seem to be a valid response from the perspective
of Glibc. In my case it caused Firefox to crash.
---
 src/handlers.rs | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/src/handlers.rs b/src/handlers.rs
index 544257b..ba2d5b5 100644
--- a/src/handlers.rs
+++ b/src/handlers.rs
@@ -200,17 +200,20 @@ pub fn handle_request(log: &Logger, request: &protocol::Request) -> Result<Vec<u
                 ..AddrInfoHints::default()
             };
 
-            let host = match getaddrinfo(Some(hostname), None, Some(hints)) {
-                Ok(addrs) => {
-                    let addresses: std::io::Result<Vec<_>> = addrs
-                        .filter(|x| match x {
-                            Err(_) => false,
-                            Ok(addr) => addr.sockaddr.is_ipv4(),
-                        })
-                        .map(|r| r.map(|a| a.sockaddr.ip()))
-                        .collect();
+            let host = match getaddrinfo(Some(hostname), None, Some(hints))
+                .map(|addrs|
+		     addrs.filter_map(|r| r.ok())
+			  .filter(|r| r.sockaddr.is_ipv4())
+			  .map(|a| a.sockaddr.ip())
+			  .collect::<Vec<_>>())
+	    {
+		// no matches found
+		Ok(addresses) if addresses.len() == 0 => {
+		    Ok(None)
+		}
+                Ok(addresses) => {
                     Ok(Some(Host {
-                        addresses: addresses?,
+                        addresses,
                         hostname: hostname.to_string(),
                     }))
                 }