When Thread.interrupt is called on a thread which is blocked on an
SSLSocket.read then the interrupt exception is masked by JSSE and
the read method returns with an end-of-stream error. I expect the
interrupt exception to be thrown, as is done for non-SSL sockets.

The LDAP provider in JNDI depends on JSSE and has a requirement to
interrupt an SSLSocket.read operation in order to switch input streams.
This can occur, for example, when a TLS connection has been established
over an existing socket (without client authentication) and the JNDI user
wishes to perform client authentication using a public key certificate.

The problem can be demonstrated using the program below.


Here is a trace of the plain socket case: the interrupt is thrown,
as expected.

% /usr/local/java/jdk1.4/solsparc/bin/java
  TestSocketInterrupt oasis.ireland.sun.com 389

Establishing a plain connection ...
Connected to: oasis.ireland.sun.com:389
Pausing for 5 seconds ...
Reading from input stream ...
Interrupting reader thread
java.io.InterruptedIOException: Interrupted system call
        at java.net.SocketInputStream.socketRead(Native Method)
        at java.net.SocketInputStream.read(SocketInputStream.java:99)
        at java.net.SocketInputStream.read(SocketInputStream.java:115)
        at TestSocketInterrupt$Reader.run(TestSocketInterrupt.java:84)




Here is a trace of the SSL socket case: the interrupt is masked.

% /usr/local/java/jdk1.4/solsparc/bin/java
  TestSocketInterrupt -ssl oasis.ireland.sun.com 636

Establishing an SSL connection ...
Connected to: oasis.ireland.sun.com:636
Pausing for 5 seconds ...
Reading from input stream ...
Interrupting reader thread
End-of-stream detected



/*
 * Copyright (c) 2000. Sun Microsystems, Inc. All rights reserved.
 */

import java.io.InputStream;
import java.net.Socket;
import javax.net.ssl.SSLContext;
import javax.net.ssl.SSLSocketFactory;

/**
 * Demonstrate that an SSL socket blocked on a read cannot be
 * interrupted correctly.
 *
 * Usage: java TestSocketInterrupt [-ssl] <hostname> <port number>
 *
 * Example: java TestSocketInterrupt -ssl oasis.ireland.sun.com 636
 *
 * Requires: JDK 1.4 (Merlin)
 */

public class TestSocketInterrupt {

    public static void main(String[] args) {

        boolean useSSL;
        String host;
        int port;
        Socket socket;

        if (args[0].equals("-ssl")) {
            useSSL = true;
            host = args[1];
            port = Integer.parseInt(args[2]);
        } else {
            useSSL = false;
            host = args[0];
            port = Integer.parseInt(args[1]);
        }

        try {
            if (useSSL) {
                System.out.println("Establishing an SSL connection ...");
                SSLContext sslCtx = SSLContext.getInstance("TLS");
                sslCtx.init(null, null, null);
                SSLSocketFactory factory = sslCtx.getSocketFactory();
                socket = (Socket) factory.createSocket(host, port);
            } else {
                System.out.println("Establishing a plain connection ...");
                socket = new Socket(host, port);
            }

            InputStream inStream = socket.getInputStream();
            System.out.println("Connected to: " + host + ":" + port);

            Reader reader = new Reader(inStream);
            reader.start();

            // sleep for 5 seconds
            System.out.println("Pausing for 5 seconds ...");
            try {
                Thread.sleep(5 * 1000);
            } catch (Exception e) {
                e.printStackTrace();
            }

            System.out.println("Interrupting reader thread");
            reader.interrupt();

        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    static class Reader extends Thread {
        private InputStream inStream;

        public Reader(InputStream inStream) {
            this.inStream = inStream;
        }

        public void run() {
            try {
                System.out.println("Reading from input stream ...");
                if (inStream.read() == -1) {
                    System.out.println("End-of-stream detected");
                }
            } catch (Exception e) {
                e.printStackTrace();
            }
        }
    }
}