From bde2bcba2bef9e1e1d75244c25499e7c86398ec0 Mon Sep 17 00:00:00 2001
From: David Kocher <dkocher@iterate.ch>
Date: Tue, 17 May 2022 10:20:12 +0200
Subject: [PATCH] Register custom DNS resolver to handle IPv6 preference.

---
 .../core/http/CustomDnsResolver.java          | 40 +++++++++++++++++++
 .../core/http/HttpConnectionPoolBuilder.java  |  1 +
 2 files changed, 41 insertions(+)
 create mode 100644 core/src/main/java/ch/cyberduck/core/http/CustomDnsResolver.java

diff --git a/core/src/main/java/ch/cyberduck/core/http/CustomDnsResolver.java b/core/src/main/java/ch/cyberduck/core/http/CustomDnsResolver.java
new file mode 100644
index 00000000000..1e47843b7f5
--- /dev/null
+++ b/core/src/main/java/ch/cyberduck/core/http/CustomDnsResolver.java
@@ -0,0 +1,40 @@
+package ch.cyberduck.core.http;
+
+/*
+ * Copyright (c) 2002-2022 iterate GmbH. All rights reserved.
+ * https://cyberduck.io/
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+import ch.cyberduck.core.DisabledCancelCallback;
+import ch.cyberduck.core.Resolver;
+import ch.cyberduck.core.exception.ResolveCanceledException;
+import ch.cyberduck.core.exception.ResolveFailedException;
+import org.apache.http.conn.DnsResolver;
+
+import java.net.InetAddress;
+import java.net.UnknownHostException;
+
+public class CustomDnsResolver implements DnsResolver {
+
+    private final Resolver resolver = new Resolver();
+
+    @Override
+    public InetAddress[] resolve(String host) throws UnknownHostException {
+        try {
+            return new InetAddress[]{resolver.resolve(host, new DisabledCancelCallback())};
+        }
+        catch(ResolveFailedException | ResolveCanceledException e) {
+            throw new UnknownHostException(e.getDetail(false));
+        }
+    }
+}
diff --git a/core/src/main/java/ch/cyberduck/core/http/HttpConnectionPoolBuilder.java b/core/src/main/java/ch/cyberduck/core/http/HttpConnectionPoolBuilder.java
index 0a62a0130ab..a3201f78b6f 100644
--- a/core/src/main/java/ch/cyberduck/core/http/HttpConnectionPoolBuilder.java
+++ b/core/src/main/java/ch/cyberduck/core/http/HttpConnectionPoolBuilder.java
@@ -180,6 +180,7 @@ public HttpClientBuilder build(final Proxy proxy, final TranscriptListener liste
                 new BackportWindowsNegotiateSchemeFactory(null) :
                 new SPNegoSchemeFactory())
             .register(AuthSchemes.KERBEROS, new KerberosSchemeFactory()).build());
+        configuration.setDnsResolver(new CustomDnsResolver());
         return configuration;
     }