Java Programming Code Examples
Java > Security Code Examples
JaasLoginCallbackHandler
JaasLoginCallbackHandler
package com.ack.security.jaas;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PushbackInputStream;
import java.util.Arrays;
import javax.security.auth.callback.Callback;
import javax.security.auth.callback.CallbackHandler;
import javax.security.auth.callback.NameCallback;
import javax.security.auth.callback.PasswordCallback;
import javax.security.auth.callback.TextOutputCallback;
import javax.security.auth.callback.UnsupportedCallbackException;
/**
* The application implements the CallbackHandler.
*
* <p> This application is text-based. Therefore it displays information
* to the user using the OutputStreams System.out and System.err,
* and gathers input from the user using the InputStream System.in.
*/
class JaasLoginCallbackHandler implements CallbackHandler {
/**
* Invoke an array of Callbacks.
*
* <p>
*
* @param callbacks an array of <code>Callback</code> objects which contain
* the information requested by an underlying security
* service to be retrieved or displayed.
*
* @exception java.io.IOException if an input or output error occurs. <p>
*
* @exception UnsupportedCallbackException if the implementation of this
* method does not support one or more of the Callbacks
* specified in the <code>callbacks</code> parameter.
*/
public void handle(Callback[] callbacks)
throws IOException, UnsupportedCallbackException {
for( int i = 0; i < callbacks.length; i++ ) {
if( callbacks[i] instanceof TextOutputCallback ) {
// display the message according to the specified type
TextOutputCallback toc = ( TextOutputCallback ) callbacks[i];
switch( toc.getMessageType() ) {
case TextOutputCallback.INFORMATION:
System.out.println(toc.getMessage());
break;
case TextOutputCallback.ERROR:
System.out.println("ERROR: " + toc.getMessage());
break;
case TextOutputCallback.WARNING:
System.out.println("WARNING: " + toc.getMessage());
break;
default:
throw new IOException("Unsupported message type: " +
toc.getMessageType());
}
} else if( callbacks[i] instanceof NameCallback ) {
// prompt the user for a username
NameCallback nc = ( NameCallback ) callbacks[i];
System.err.print(nc.getPrompt());
System.err.flush();
nc.setName((new BufferedReader
(new InputStreamReader(System.in))).readLine());
} else if( callbacks[i] instanceof PasswordCallback ) {
// prompt the user for sensitive information
PasswordCallback pc = ( PasswordCallback ) callbacks[i];
System.err.print(pc.getPrompt());
System.err.flush();
pc.setPassword(readPassword(System.in));
} else {
throw new UnsupportedCallbackException
(callbacks[i], "Unrecognized Callback");
}
}
}
// Reads user password from given input stream.
private char[] readPassword(InputStream in) throws IOException {
char[] lineBuffer;
char[] buf;
int i;
buf = lineBuffer = new char[128];
int room = buf.length;
int offset = 0;
int c;
loop: while( true ) {
switch( c = in.read() ) {
case -1:
case '\n':
break loop;
case '\r':
int c2 = in.read();
if( (c2 != '\n') && (c2 != -1) ) {
if( !(in instanceof PushbackInputStream) ) {
in = new PushbackInputStream(in);
}
(( PushbackInputStream ) in).unread(c2);
} else
break loop;
default:
if( --room < 0 ) {
buf = new char[offset + 128];
room = buf.length - offset - 1;
System.arraycopy(lineBuffer, 0, buf, 0, offset);
Arrays.fill(lineBuffer, ' ');
lineBuffer = buf;
}
buf[offset++] = ( char ) c;
break;
}
}
if( offset == 0 ) {
return null;
}
char[] ret = new char[offset];
System.arraycopy(buf, 0, ret, 0, offset);
Arrays.fill(buf, ' ');
return ret;
}
}
