Manuel Dominguez Sarmiento created FTPSERVER-476:
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Summary: NullPointerException when SessionFilter.accept() returns
false
Key: FTPSERVER-476
URL: https://issues.apache.org/jira/browse/FTPSERVER-476
Project: FtpServer
Issue Type: Bug
Components: Core
Affects Versions: 1.1.0
Reporter: Manuel Dominguez Sarmiento
We have the following code for setting up listeners before starting the FTP
server:
ListenerFactory listenerFactory = new ListenerFactory();
listenerFactory.setPort(controlPort);
listenerFactory.setDataConnectionConfiguration(dataConnectionConfig);
listenerFactory.setSessionFilter(new SessionFilter() {
@Override
public boolean accept(IoSession ioSession) {
InetAddress address = ((InetSocketAddress)
ioSession.getRemoteAddress()).getAddress();
boolean accept = !enableIpSecurity ||
allowedIpAddresses.contains(address.getHostAddress());
if (accept) {
log.info("Login attempt from " +
address.getHostAddress() + " successful");
} else {
log.warn("Login attempt from " +
address.getHostAddress() + " failed");
}
return accept;
}
});
Listener listener = listenerFactory.createListener();
When SessionFilter.accept() returns false everything works fine from the user
standpoint, however we get the following stack trace in the logs:
[WARN ] 2016-11-02 10:35:39 [DefaultFtpHandler-pool-29-thread-1] - Data
connection threw an exception on disconnect
java.lang.NullPointerException
at
org.apache.ftpserver.impl.IODataConnectionFactory.<init>(IODataConnectionFactory.java:80)
at
org.apache.ftpserver.impl.FtpIoSession.getDataConnection(FtpIoSession.java:554)
at
org.apache.ftpserver.impl.DefaultFtpHandler.sessionClosed(DefaultFtpHandler.java:106)
at
org.apache.ftpserver.listener.nio.FtpHandlerAdapter.sessionClosed(FtpHandlerAdapter.java:72)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.sessionClosed(DefaultIoFilterChain.java:797)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:504)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:48)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:927)
at
org.apache.mina.filter.logging.LoggingFilter.sessionClosed(LoggingFilter.java:238)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:504)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:48)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:927)
at
org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:109)
at
org.apache.mina.filter.logging.MdcInjectionFilter.filter(MdcInjectionFilter.java:135)
at
org.apache.mina.filter.util.CommonEventFilter.sessionClosed(CommonEventFilter.java:55)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:504)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:48)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:927)
at
org.apache.mina.filter.codec.ProtocolCodecFilter.sessionClosed(ProtocolCodecFilter.java:360)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextSessionClosed(DefaultIoFilterChain.java:504)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain.access$900(DefaultIoFilterChain.java:48)
at
org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.sessionClosed(DefaultIoFilterChain.java:927)
at
org.apache.mina.core.filterchain.IoFilterEvent.fire(IoFilterEvent.java:109)
at org.apache.mina.core.session.IoEvent.run(IoEvent.java:63)
at
org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTask(OrderedThreadPoolExecutor.java:770)
at
org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.runTasks(OrderedThreadPoolExecutor.java:762)
at
org.apache.mina.filter.executor.OrderedThreadPoolExecutor$Worker.run(OrderedThreadPoolExecutor.java:704)
at java.lang.Thread.run(Thread.java:745)
What seems to be happening is that the constructor for IODataConnectionFactory
is expecting the session parameter to be non-null however since
SessionFilter.accept() returns false, then this is not the case:
if (session.getListener().getDataConnectionConfiguration().isImplicitSsl())
{
secure = true;
}
Thus we get a NullPointerException. This snippet should probably be changed to:
if (session != null &&
session.getListener().getDataConnectionConfiguration().isImplicitSsl()) {
secure = true;
}
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