How to pass parameter in wordpress url?

need Java applet to test whether user machine can receive incoming connections

• I need a straightforward Java applet written. The purpose of the applet is to determine whether a user's computer is able to receive incoming connections on a given TCP port -- so that they can determine whether they will be able to install a piece of software that acts as a server and responds to incoming connections. (There are a couple of obstacles that might prevent a machine from listening for incoming connections -- a hardware firewall, the built-in Windows XP firewall, etc.) The java applet should run on a Web page and take these parameters: - listening_port - detection_script_url - success_url - failure_url - error_url What the applet should do is: 1. start listening on the port number specified by listening_port 2. detect the user's local IP address, and send a request to the URL: - detection_script_url + '?ip=' + <local ip address> 3. the script at that URL will attempt to connect to the Java applet. The Java applet doesn't have to do anything in response to this. But once the script has attempted to connect, the script outputs either "Yes" or "No" over HTTP -- or, it outputs something to indicate whether the connection was successful. I've heard that XML/SOAP/something along those lines is the most supported way to pass parameter information over the Web like that. Since I'll be writing the server-side script, just let me know what output you need. 4. If the script outputs that the connection was succcessful, the applet redirects the browser to success_url. If the script outputs that the connection failed, the applet redirects the browser to failure_url. If there is an error accessing the script itself, redirect the browser to error_url. It may be that the Java applet has to be signed in order to listen for incoming connections, even if it's just listening for incoming connections from the same server that served it. If that's the case, please let me know what I have to do to get it signed, after it's written.

• Answer:

  Hi, I constructed an applet according to your specifications. This applet opens a socket on a given port, then contacts a server script which will test the connection on that port. If the server returns a response containing the string "SUCCESS" (the response can be plain text, xml or soap as long as it contains this string in case of success), the applet will redirect the user to the success page, else the user will be redirected to the failure page. If the applet fails to contact the server script, the user will be redirected to the error page. The applet will pass the client ip address to the script as a parameter "ip", however this will only work if the applet is signed (which you're free to do). Even if the applet is signed, however, it is still possible an internal network address is returned in stead of the internet ip. Ideally, the script will determine the actual client ip from the request. I included a sample servlet script, implemented as a java servlet (and an alternative in the form of a jsp page), which tests the socket connection and retrieves the actual client ip from the request. The client ip will usually be correct, except if a non-transparant proxy is used by the client. Notice that the server where the script is hosted needs to allow direct (non-http) tcp connections, for the script to be able to contact the client. You can retrieve the applet archive, as well as the source code to the applet and scripts here: http://users.pandora.be/rami/tcp/ The applet can be used in debug mode, in which case it will not redirect, but simply display the parameters, result and error messages (if any). Debug mode can be used with the "debug" parameter: <APPLET CODE="TCPApplet" ARCHIVE="TCPApplet.jar" WIDTH=600 HEIGHT=200> <param name="listening_port" value="1234"> <param name="detection_script_url" value="script.jsp"> <param name="success_url" value="success.html"> <param name="failure_url" value="failure.html"> <param name="error_url" value="error.html"> <param name="socket_timeout" value="5000"> <param name="debug" value="true"> </APPLET> To enable the redirect mode, use the applet as follows: <APPLET CODE="TCPApplet" ARCHIVE="TCPApplet.jar" WIDTH=0 HEIGHT=0> <param name="listening_port" value="1234"> <param name="detection_script_url" value="script.jsp"> <param name="success_url" value="success.html"> <param name="failure_url" value="failure.html"> <param name="error_url" value="error.html"> <param name="socket_timeout" value="5000"> </APPLET> The "socket_timeout" parameter is optional (defaults to 10000) and defines the time the socket remains open (in ms). If the applet is not signed, the script url should be hosted on the same server the applet was downloaded from! Use relative path names in this case (the applet will automaticall append the code base to the url, except if the url starts with "http://"). Below you'll find a printout of the applet source: //--------------------- START APPLET --------------------- // import java.applet.*; import java.io.*; import java.net.*; import java.awt.*; /** * This applet opens a socket on a given port, then contacts a server script * which will test the connection on that port. If the server returns a response * containing the string "SUCCESS", the applet will redirect the user to the success * page, else the user will be redirected to the failure page. If the applet fails * to contact the server script, the user will be redirected to the error page. * The applet will pass the client ip address to the script as a parameter "ip", * however this will only work if the applet is signed and may be a network * address. Ideally, the script will determine the actual client ip from the request. */ public class TCPApplet extends Applet { // applet parameters names private static final String PARAM_PORT = "listening_port"; private static final String PARAM_SCRIPT = "detection_script_url"; private static final String PARAM_SUCCESS = "success_url"; private static final String PARAM_FAILURE = "failure_url"; private static final String PARAM_ERROR = "error_url"; private static final String PARAM_TIMEOUT = "socket_timeout"; private static final String PARAM_DEBUG = "debug"; // the expected success string to be contained in the server script response private static final String RESPONSE_SUCCESS = "SUCCESS"; // applet parameters private String listenPort; private String scriptUrl; private String successUrl; private String failureUrl; private String errorUrl; private boolean debug; private int socketTimeOut; /** * This thread opens a connection for a time period defined by * "socket_timeout" and excepts connections from a server script. */ private class PortListnerThread implements Runnable { public void run() { ServerSocket socket = null; Socket connectionSocket = null; try { // open a socket on the defined port socket = new ServerSocket(Integer.parseInt(listenPort)); socket.setSoTimeout(socketTimeOut); connectionSocket = socket.accept(); BufferedReader in = new BufferedReader(new InputStreamReader(connectionSocket.getInputStream())); // read some input from socket, to allow server script to test connection in.readLine(); } catch (Exception exc) { System.out.println(exc.getMessage()); } finally { if (connectionSocket != null) { try { connectionSocket.close(); } catch (Exception exc) {} } if (socket != null) { try { socket.close(); } catch (Exception exc) {} } } } } /** * Initializes the applet and retrieves the applet parameters */ public void init() { listenPort = getParameter(PARAM_PORT); scriptUrl = getParameter(PARAM_SCRIPT); successUrl = getParameter(PARAM_SUCCESS); failureUrl = getParameter(PARAM_FAILURE); errorUrl = getParameter(PARAM_ERROR); debug = "true".equalsIgnoreCase(getParameter(PARAM_DEBUG)); try { socketTimeOut = Integer.parseInt(getParameter(PARAM_TIMEOUT)); } catch (Exception exc) { // default socket timeout: 10 seconds socketTimeOut = 10000; } // lookup local ip address and add it to the script url String ipAddress = null; try { // this will only work if the applet is signed! Else 127.0.0.1 will be returned // furthermore, on networks, the internal network address will be returned InetAddress ia = InetAddress.getLocalHost(); ipAddress = ia.getHostAddress(); } catch (Exception exc) { // unable to determine local ip address ipAddress = "127.0.0.1"; } scriptUrl += "?ip="+ipAddress; } /** * Writes debug info in debug mode or redirects to the correct url otherwise */ public void paint(Graphics g) { if (debug) { // Show debug info g.drawString("Port is: " + listenPort, 20, 20); g.drawString("Script url is: " + scriptUrl, 20, 40); g.drawString("Success url is: " + successUrl, 20, 60); g.drawString("Failure url is: " + failureUrl, 20, 80); g.drawString("Error url is: " + errorUrl, 20, 100); g.drawString("Socket timeout is: " + socketTimeOut + "ms", 20, 120); try { g.drawString("Result is: " + checkPort(), 20, 140); } catch (Exception exc) { g.drawString("Exception: " + exc.getMessage(), 20, 140); } } else { // perform redirect try { String result = checkPort(); URL redirectURL; if (result.startsWith("http://")) redirectURL = new URL(scriptUrl); else redirectURL = new URL(getCodeBase(),result); getAppletContext().showDocument(redirectURL); } catch (MalformedURLException mue) { mue.printStackTrace(); } } } /** * Starts a thread listner on the defined port and queries the server script. * If the script response contains "SUCCESS", the success url is returned, * otherwise the failure url is returned. If the server cannot be contacted, * the error url is returned. */ private String checkPort() { // open a socket listner thread for the server to connect to Thread listner = new Thread(new PortListnerThread()); listner.start(); try { // contact the server script StringBuffer scriptResponse = new StringBuffer(); URL url; if (scriptUrl.startsWith("http://")) url = new URL(scriptUrl); else url = new URL(getCodeBase(),scriptUrl); URLConnection conn = url.openConnection(); conn.setRequestProperty("Accept", "text/*"); // read script response BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream())); String line = null; while ( (line = reader.readLine()) != null) { scriptResponse.append(line); } reader.close(); if (scriptResponse.toString().toUpperCase().indexOf(RESPONSE_SUCCESS)>0) return successUrl; else return failureUrl; } catch (Exception exc) { exc.printStackTrace(); return errorUrl; } } } //--------------------- END APPLET --------------------- // A sample server script JSP might look something like this: <% // Sample server script try{ // open a socket to client java.net.Socket clientSocket = new java.net.Socket(request.getRemoteAddr(), 1234); java.io.DataOutputStream outToServer = new java.io.DataOutputStream(clientSocket.getOutputStream()); // write anything to the socket to test the connection outToServer.writeBytes("socket test"); clientSocket.close(); %>SOCKET CONNECT SUCCESS<% } catch (Exception exc) { %>SOCKET CONNECT FAILED<% } %> A Java servlet version of the same script would be: //--------------------- START SERVLET --------------------- // import java.io.*; import java.util.*; import java.net.*; import javax.servlet.*; import javax.servlet.http.*; /** * Sample servlet to test the applet functionality */ public class TCPServlet extends HttpServlet { private static final String PARAM_IP = "ip"; private static final int PORT = 1234; /** * Handle applet requests */ public void doGet(HttpServletRequest req, HttpServletResponse res) throws IOException, ServletException { try { // the ip returned by the applet (might be network address) String ip = req.getParameter(PARAM_IP); // the actual client request ip String clientIp = req.getRemoteAddr(); // open a socket Socket clientSocket = new Socket(clientIp, PORT); DataOutputStream outToServer = new DataOutputStream(clientSocket.getOutputStream()); // write anything to the socket to test the connection outToServer.writeBytes("socket test"); clientSocket.close(); // return a response containing the "SUCCESS" string to the applet res.getOutputStream().print("SOCKET CONNECT SUCCESS"); } catch (Exception exc) { res.getOutputStream().print("SOCKET CONNECT FAILED"); } res.getOutputStream().close(); } } //--------------------- END SERVLET --------------------- // The applet has been tested using the Java Virtual Machine plugin. I haven't had the chance of testing it on the Microsoft Virtual Machine yet. I'll do that as soon as possible and post an updated version if problems would occur. I hope this allows you to complete your project. If you have any questions or problems feel free to ask for clarification! Kind regards, rhansenne-ga.