Moves logic of name resolution to DefaultDnsResolver from TcpClientCo…

…nnection. New tests for DefaultDnsResolver.

webclient/api/src/main/java/io/helidon/webclient/api/DefaultDnsResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2023 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,7 @@
 package io.helidon.webclient.api;
 
 import java.net.InetAddress;
+import java.net.UnknownHostException;
 
 import io.helidon.webclient.spi.DnsResolver;
 
@@ -46,7 +47,15 @@ public boolean useDefaultJavaResolver() {
 
     @Override
     public InetAddress resolveAddress(String hostname, DnsAddressLookup dnsAddressLookup) {
-        throw new IllegalStateException("This DNS resolver is not meant to be used.");
+        try {
+            InetAddress[] addresses = InetAddress.getAllByName(hostname);
+            addresses = dnsAddressLookup.filter(addresses);
+            if (addresses.length > 0) {
+                return addresses[0];
+            }
+        } catch (UnknownHostException e) {
+            // falls through
+        }
+        throw new IllegalArgumentException("Failed to get address from host: " + hostname);
     }
-
 }

webclient/api/src/main/java/io/helidon/webclient/api/TcpClientConnection.java

@@ -246,21 +246,8 @@ private String createChannelId(Socket socket) {
 
     private InetSocketAddress inetSocketAddress() {
         DnsResolver dnsResolver = connectionKey.dnsResolver();
-        if (dnsResolver.useDefaultJavaResolver()) {
-            try {
-                InetAddress[] addresses = InetAddress.getAllByName(connectionKey.host());
-                addresses = connectionKey.dnsAddressLookup().filter(addresses);
-                if (addresses.length > 0) {
-                    return new InetSocketAddress(addresses[0], connectionKey.port());
-                }
-            } catch (UnknownHostException e) {
-                // falls through
-            }
-            throw new IllegalArgumentException("Failed to get address from host: " + connectionKey.host());
-        } else {
-            InetAddress address = dnsResolver.resolveAddress(connectionKey.host(), connectionKey.dnsAddressLookup());
-            return new InetSocketAddress(address, connectionKey.port());
-        }
+        InetAddress address = dnsResolver.resolveAddress(connectionKey.host(), connectionKey.dnsAddressLookup());
+        return new InetSocketAddress(address, connectionKey.port());
     }
 
     private void debugTls(SSLSocket sslSocket) {

webclient/api/src/test/java/io/helidon/webclient/api/DefaultDnsResolverTest.java

@@ -0,0 +1,40 @@
+/*
+ * Copyright (c) 2024 Oracle and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.helidon.webclient.api;
+
+import java.net.InetAddress;
+
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.CoreMatchers.is;
+
+class DefaultDnsResolverTest {
+
+    @Test
+    void testIpv4Resolution() {
+        DefaultDnsResolver resolver = DefaultDnsResolver.create();
+        InetAddress inetAddress  = resolver.resolveAddress("localhost", DnsAddressLookup.IPV4_PREFERRED);
+        assertThat(inetAddress.getHostAddress(), is("127.0.0.1"));
+    }
+
+    @Test
+    void testIpv6Resolution() {
+        DefaultDnsResolver resolver = DefaultDnsResolver.create();
+        InetAddress inetAddress  = resolver.resolveAddress("localhost", DnsAddressLookup.IPV6_PREFERRED);
+        assertThat(inetAddress.getHostAddress(), is("0:0:0:0:0:0:0:1"));
+    }
+}