ZOOKEEPER-4819 Fix can't seek for writable tls server if connected to…

… readonly server

ClientCnxn::pingRwServer uses raw socket to issue "isro" 4lw command.
This results in unsuccessful handshake to tls server. Use SSLSocket
when zookeeper.client.secure is set to true.

zookeeper-server/src/main/java/org/apache/zookeeper/ClientCnxn.java

@@ -43,6 +43,9 @@
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.ThreadLocalRandom;
 import java.util.concurrent.atomic.AtomicReference;
+import javax.net.ssl.SSLContext;
+import javax.net.ssl.SSLSocket;
+import javax.net.ssl.SSLSocketFactory;
 import javax.security.auth.login.LoginException;
 import javax.security.sasl.SaslException;
 import org.apache.jute.BinaryInputArchive;
@@ -70,7 +73,10 @@
 import org.apache.zookeeper.client.HostProvider;
 import org.apache.zookeeper.client.ZKClientConfig;
 import org.apache.zookeeper.client.ZooKeeperSaslClient;
+import org.apache.zookeeper.common.ClientX509Util;
 import org.apache.zookeeper.common.Time;
+import org.apache.zookeeper.common.X509Exception;
+import org.apache.zookeeper.common.X509Util;
 import org.apache.zookeeper.proto.AuthPacket;
 import org.apache.zookeeper.proto.ConnectRequest;
 import org.apache.zookeeper.proto.Create2Response;
@@ -1307,18 +1313,15 @@ private void pingRwServer() throws RWServerFoundException {
             Socket sock = null;
             BufferedReader br = null;
             try {
-                sock = new Socket(addr.getHostString(), addr.getPort());
-                sock.setSoLinger(false, -1);
-                sock.setSoTimeout(1000);
-                sock.setTcpNoDelay(true);
+                sock = newSocket(addr);
                 sock.getOutputStream().write("isro".getBytes());
                 sock.getOutputStream().flush();
                 sock.shutdownOutput();
                 br = new BufferedReader(new InputStreamReader(sock.getInputStream()));
                 result = br.readLine();
             } catch (ConnectException e) {
                 // ignore, this just means server is not up
-            } catch (IOException e) {
+            } catch (IOException | X509Exception.SSLContextException e) {
                 // some unexpected error, warn about it
                 LOG.warn("Exception while seeking for r/w server.", e);
             } finally {
@@ -1348,6 +1351,28 @@ private void pingRwServer() throws RWServerFoundException {
             }
         }
 
+        private Socket newSocket(InetSocketAddress addr) throws IOException, X509Exception.SSLContextException {
+            boolean useSecure = clientConfig.getBoolean(ZKClientConfig.SECURE_CLIENT);
+            Socket sock;
+            if (useSecure) {
+                try (X509Util util = new ClientX509Util()) {
+                    SSLContext sslContext = util.createSSLContext(clientConfig);
+                    SSLSocketFactory socketFactory = sslContext.getSocketFactory();
+                    SSLSocket sslSock = (SSLSocket) socketFactory.createSocket();
+                    sslSock.connect(addr);
+                    sslSock.startHandshake();
+                    sock = sslSock;
+                }
+            } else {
+                sock = new Socket(addr.getHostString(), addr.getPort());
+            }
+
+            sock.setSoLinger(false, -1);
+            sock.setSoTimeout(1000);
+            sock.setTcpNoDelay(true);
+            return sock;
+        }
+
         private void cleanup() {
             clientCnxnSocket.cleanup();
             synchronized (pendingQueue) {