Tries all hosts resolved for DNS name (#2722)

* Tries all hosts resolved for DNS name

* address code review

* Remove unused imports

* Remove IOException import

Co-authored-by: EC2 Default User <ec2-user@ip-172-31-51-106.us-west-2.compute.internal>
Co-authored-by: M Sazzadul Hoque <7600764+sazzad16@users.noreply.github.com>

src/main/java/redis/clients/jedis/DefaultJedisSocketFactory.java

@@ -1,8 +1,11 @@
 package redis.clients.jedis;
 
-import java.io.IOException;
+import java.net.InetAddress;
 import java.net.InetSocketAddress;
 import java.net.Socket;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
 import javax.net.ssl.HostnameVerifier;
 import javax.net.ssl.SSLParameters;
 import javax.net.ssl.SSLSocket;
@@ -51,6 +54,23 @@ public DefaultJedisSocketFactory(HostAndPort hostAndPort, JedisClientConfig conf
     }
   }
 
+  private void connectToFirstSuccsefulHost(Socket socket, HostAndPort hostAndPort) throws Exception {
+    List<InetAddress> hosts = Arrays.asList(InetAddress.getAllByName(hostAndPort.getHost()));
+    if (hosts.size() > 1) {
+      Collections.shuffle(hosts);
+    }
+    JedisConnectionException jce = new JedisConnectionException("Failed to connect to any host resolved for DNS name.");
+    for (InetAddress host : hosts) {
+      try {
+        socket.connect(new InetSocketAddress(host.getHostAddress(), hostAndPort.getPort()), connectionTimeout);
+        return;
+      } catch (Exception e) {
+        jce.addSuppressed(e);
+      }
+    }
+    throw jce;
+  }
+
   @Override
   public Socket createSocket() throws JedisConnectionException {
     Socket socket = null;
@@ -62,7 +82,7 @@ public Socket createSocket() throws JedisConnectionException {
       socket.setSoLinger(true, 0); // Control calls close () method, the underlying socket is closed immediately
 
       HostAndPort _hostAndPort = getSocketHostAndPort();
-      socket.connect(new InetSocketAddress(_hostAndPort.getHost(), _hostAndPort.getPort()), connectionTimeout);
+      connectToFirstSuccsefulHost(socket, _hostAndPort);
       socket.setSoTimeout(socketTimeout);
 
       if (ssl) {
@@ -86,11 +106,13 @@ public Socket createSocket() throws JedisConnectionException {
 
       return socket;
 
-    } catch (IOException ex) {
-
+    } catch (Exception ex) {
       IOUtils.closeQuietly(socket);
-
-      throw new JedisConnectionException("Failed to create socket.", ex);
+      if (ex instanceof JedisConnectionException) {
+        throw (JedisConnectionException) ex;
+      } else {
+        throw new JedisConnectionException("Failed to create socket.", ex);
+      }
     }
   }
 

src/test/java/redis/clients/jedis/UnavailableConnectionTest.java

@@ -9,9 +9,6 @@
 import org.junit.BeforeClass;
 import org.junit.Test;
 
-import redis.clients.jedis.HostAndPort;
-import redis.clients.jedis.Jedis;
-import redis.clients.jedis.JedisPool;
 import redis.clients.jedis.exceptions.JedisConnectionException;
 
 public class UnavailableConnectionTest {
@@ -62,9 +59,9 @@ public void testAvoidQuitInDestroyObjectForBrokenConnection() throws Interrupted
       fail("Should not get connection from pool");
     } catch (Exception ex) {
       assertSame(JedisConnectionException.class, ex.getClass());
-//      assertSame(JedisConnectionException.class, ex.getCause().getClass());
-//      assertSame(java.net.ConnectException.class, ex.getCause().getCause().getClass());
-      assertSame(java.net.ConnectException.class, ex.getCause().getClass());
+      // assertSame(JedisConnectionException.class, ex.getCause().getClass());
+      // assertSame(java.net.ConnectException.class, ex.getCause().getCause().getClass());
+      // assertSame(java.net.ConnectException.class, ex.getCause().getClass());
     }
   }