How do I check if a SSLSocket connection is sane on Java?

Question

Hi, I have a SSLSocket pool and I need to check if the socket connection is sane before borrowing the object.

The isConnected, isInputShutdown and isOutputShutdown are useless because they don't check if both sides are connected and if I try to write or read from the socket I might get a SocketException.

Here is my code for testing a connection:

        if(sslSocket.isConnected() && 
               !sslSocket.isInputShutdown() && 
               !sslSocket.isOutputShutdown()){
            valid = true;
        }

This code doesn't work, as explained above.

So, what is the best way to check if a SSLSocket (or a regular Socket) is sane?

Thank you.

Answer 1

Would trying to read from the socket and catching a SocketException not be sane enough?

Answer 2

If by "sane" you mean connected, you can only detect that a TCP socket is disconnected once you've tried to write to it:

http://lkml.indiana.edu/hypermail/linux/kernel/0106.1/1154.html

Hence, you need to make use of the exception accordingly in Java.

Answer 3

If reading, set a readTimeout via Socket.setSoTimeout() and catch SocketTimeoutException, or write and catch an IOException: connection reset. There are no other mechanisms. The isXXX() APIs you mention only tell you what you have done to this Socket. They don't tell you anything about the state of the connection.