8234408: Improve TLS session handling

Reviewed-by: andrew

src/share/classes/sun/security/ssl/ClientHandshaker.java

@@ -1337,7 +1337,7 @@ final class ClientHandshaker extends Handshaker {
     @Override
     HandshakeMessage getKickstartMessage() throws SSLException {
         // session ID of the ClientHello message
-        SessionId sessionId = SSLSessionImpl.nullSession.getSessionId();
+        SessionId sessionId = new SessionId(new byte[0]);
 
         // a list of cipher suites sent by the client
         CipherSuiteList cipherSuites = getActiveCipherSuites();

src/share/classes/sun/security/ssl/SSLEngineImpl.java

@@ -375,7 +375,7 @@ final public class SSLEngineImpl extends SSLEngine {
         }
 
         sslContext = ctx;
-        sess = SSLSessionImpl.nullSession;
+        sess = new SSLSessionImpl();
         handshakeSession = null;
 
         /*

src/share/classes/sun/security/ssl/SSLSessionImpl.java

@@ -73,11 +73,6 @@ import static sun.security.ssl.CipherSuite.KeyExchange.*;
  */
 final class SSLSessionImpl extends ExtendedSSLSession {
 
-    /*
-     * we only really need a single null session
-     */
-    static final SSLSessionImpl         nullSession = new SSLSessionImpl();
-
     // compression methods
     private static final byte           compression_null = 0;
 
@@ -148,7 +143,7 @@ final class SSLSessionImpl extends ExtendedSSLSession {
      * be used either by a client or by a server, as a connection is
      * first opened and before handshaking begins.
      */
-    private SSLSessionImpl() {
+    SSLSessionImpl() {
         this(ProtocolVersion.NONE, CipherSuite.C_NULL, null,
             new SessionId(false, null), null, -1, false, null);
     }
@@ -657,14 +652,6 @@ final class SSLSessionImpl extends ExtendedSSLSession {
      */
     @Override
     synchronized public void invalidate() {
-        //
-        // Can't invalidate the NULL session -- this would be
-        // attempted when we get a handshaking error on a brand
-        // new connection, with no "real" session yet.
-        //
-        if (this == nullSession) {
-            return;
-        }
         invalidated = true;
         if (debug != null && Debug.isOn("session")) {
             System.out.println("%% Invalidated:  " + this);

src/share/classes/sun/security/ssl/SSLSocketImpl.java

@@ -610,7 +610,7 @@ final public class SSLSocketImpl extends BaseSSLSocketImpl {
      */
     private void init(SSLContextImpl context, boolean isServer) {
         sslContext = context;
-        sess = SSLSessionImpl.nullSession;
+        sess = new SSLSessionImpl();
         handshakeSession = null;
 
         /*