Close Session when closing SCPEngine or SFTPEngine (#926)

Co-authored-by: Jeroen van Erp <[email protected]>

src/main/java/net/schmizz/sshj/sftp/SFTPEngine.java

@@ -48,6 +48,7 @@ public class SFTPEngine
 
     protected final PathHelper pathHelper;
 
+    private final Session session;
     protected final Session.Subsystem sub;
     protected final PacketReader reader;
     protected final OutputStream out;
@@ -63,7 +64,7 @@ public SFTPEngine(SessionFactory ssh)
 
     public SFTPEngine(SessionFactory ssh, String pathSep)
             throws SSHException {
-        Session session = ssh.startSession();
+        session = ssh.startSession();
         loggerFactory = session.getLoggerFactory();
         log = loggerFactory.getLogger(getClass());
         sub = session.startSubsystem("sftp");
@@ -346,6 +347,7 @@ public void close()
             throws IOException {
         sub.close();
         reader.interrupt();
+        session.close();
     }
 
     protected LoggerFactory getLoggerFactory() {

src/main/java/net/schmizz/sshj/xfer/scp/SCPEngine.java

@@ -19,6 +19,7 @@
 import net.schmizz.sshj.common.LoggerFactory;
 import net.schmizz.sshj.common.SSHException;
 import net.schmizz.sshj.common.StreamCopier;
+import net.schmizz.sshj.connection.channel.direct.Session;
 import net.schmizz.sshj.connection.channel.direct.Session.Command;
 import net.schmizz.sshj.connection.channel.direct.SessionFactory;
 import net.schmizz.sshj.xfer.TransferListener;
@@ -41,6 +42,7 @@ class SCPEngine {
     private final SessionFactory host;
     private final TransferListener listener;
 
+    private Session session;
     private Command scp;
     private int exitStatus;
 
@@ -82,7 +84,8 @@ void cleanSlate() {
 
     void execSCPWith(ScpCommandLine commandLine)
             throws SSHException {
-        scp = host.startSession().exec(commandLine.toCommandLine());
+        session = host.startSession();
+        scp = session.exec(commandLine.toCommandLine());
     }
 
     void exit() {
@@ -102,6 +105,10 @@ void exit() {
                 log.warn("SCP exit signal: {}", scp.getExitSignal());
             }
         }
+        if(session != null) {
+            IOUtils.closeQuietly(session);
+            session = null;
+        }
 
         scp = null;
     }