v1_SSLSessionReuseFTPSClient.java

import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.net.Socket;
import java.util.Locale;

import javax.net.ssl.SSLSession;
import javax.net.ssl.SSLSessionContext;
import javax.net.ssl.SSLSocket;

import org.apache.commons.net.ftp.FTPSClient;

import com.google.common.base.Throwables;

public class v1_SSLSessionReuseFTPSClient extends FTPSClient {

    // adapted from: https://trac.cyberduck.io/changeset/10760
    @Override
    protected void _prepareDataSocket_(final Socket socket) throws IOException {
        if(socket instanceof SSLSocket) {
            final SSLSession session = ((SSLSocket) _socket_).getSession();
            final SSLSessionContext context = session.getSessionContext();
            try {
                final Field sessionHostPortCache = context.getClass().getDeclaredField("sessionHostPortCache");
                sessionHostPortCache.setAccessible(true);
                final Object cache = sessionHostPortCache.get(context);
                final Method method = cache.getClass().getDeclaredMethod("put", Object.class, Object.class);
                method.setAccessible(true);
                final String key = String.format("%s:%s", socket.getInetAddress().getHostName(),
                                                 String.valueOf(socket.getPort())).toLowerCase(Locale.ROOT);
                method.invoke(cache, key, session);
            } catch(Exception e) {
                throw Throwables.propagate(e);
            }
        }
    }

}