// httpdFileHandler.java
// -----------------------
// (C) by Michael Peter Christen; mc@anomic.de
// first published on http://www.anomic.de
// Frankfurt, Germany, 2004
// last change: 22.06.2004
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// Using this software in any meaning (reading, learning, copying, compiling,
// running) means that you agree that the Author(s) is (are) not responsible
// for cost, loss of data or any harm that may be caused directly or indirectly
// by usage of this softare or this documentation. The usage of this software
// is on your own risk. The installation and usage (starting/running) of this
// software may allow other people or application to access your computer and
// any attached devices and is highly dependent on the configuration of the
// software which must be done by the user of the software; the author(s) is
// (are) also not responsible for proper configuration and usage of the
// software, even if provoked by documentation provided together with
// the software.
//
// Any changes to this file according to the GPL as documented in the file
// gpl.txt aside this file in the shipment you received can be done to the
// lines that follows this copyright notice here, but changes must not be
// done inside the copyright notive above. A re-distribution must contain
// the intact and unchanged copyright notice.
// Contributions and changes to the program code must be marked as such.


/*
 Class documentation:
 this class provides a file servlet and CGI interface
 for the httpd server.
 Whenever this server is addressed to load a local file,
 this class searches for the file in the local path as
 configured in the setting property 'rootPath'
 The servlet loads the file and returns it to the client.
 Every file can also act as an template for the built-in
 CGI interface. There is no specific path for CGI functions.
 CGI functionality is triggered, if for the file to-be-served
 'template.html' also a file 'template.class' exists. Then,
 the class file is called with the GET/POST properties that
 are attached to the http call.
 Possible variable hand-over are:
 - form method GET
 - form method POST, enctype text/plain
 - form method POST, enctype multipart/form-data
 The class that creates the CGI respond must have at least one
 static method of the form
 public static java.util.Hashtable respond(java.util.HashMap, serverSwitch)
 In the HashMap, the GET/POST variables are handed over.
 The return value is a Property object that contains replacement
 key/value pairs for the patterns in the template file.
 The templates must have the form
 either '#['<name>']#' for single attributes, or
 '#{'<enumname>'}#' and '#{/'<enumname>'}#' for enumerations of
 values '#['<value>']#'.
 A single value in repetitions/enumerations in the template has
 the property key '_'<enumname><count>'_'<value>
 Please see also the example files 'test.html' and 'test.java'
 */

package de.anomic.http;

import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.PushbackInputStream;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Date;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Properties;
import java.util.zip.GZIPOutputStream;

import de.anomic.server.serverClassLoader;
import de.anomic.server.serverCodings;
import de.anomic.server.serverCore;
import de.anomic.server.serverFileUtils;
import de.anomic.server.serverObjects;
import de.anomic.server.serverSwitch;
import de.anomic.server.logging.serverLog;

public final class httpdFileHandler extends httpdAbstractHandler implements httpdHandler {
    
    // class variables   
    private Properties mimeTable = null;
    private serverClassLoader provider = null;
    private File htRootPath = null;
    private File htDocsPath = null;
    private File htTemplatePath = null;
    private HashMap templates = null;
    private String[] defaultFiles = null;
    private File htDefaultPath = null;
    private File htLocalePath = null;
    private serverSwitch switchboard;
    private MessageDigest md5Digest = null;
    
    public httpdFileHandler(serverSwitch switchboard) {
        this.switchboard = switchboard;
        
        // creating a logger
        this.theLogger = new serverLog("FILEHANDLER");
        
        if (this.mimeTable == null) {
            // load the mime table
            this.mimeTable = new Properties();
            String mimeTablePath = switchboard.getConfig("mimeConfig","");
            FileInputStream mimeTableInputStream = null;
            try {
                serverLog.logSystem("HTTPDFiles", "Loading mime mapping file " + mimeTablePath);
                mimeTableInputStream = new FileInputStream(new File(switchboard.getRootPath(), mimeTablePath));
                this.mimeTable.load(mimeTableInputStream);
            } catch (Exception e) {                
                serverLog.logError("HTTPDFiles", "ERROR: path to configuration file or configuration invalid\n" + e);
                System.exit(1);
            } finally {
                if (mimeTableInputStream != null) try { mimeTableInputStream.close(); } catch (Exception e1) {}                
            }
        }
        
        // create default files array
        defaultFiles = switchboard.getConfig("defaultFiles","index.html").split(",");
        if (defaultFiles.length == 0) defaultFiles = new String[] {"index.html"};
        
        // create a htRootPath: system pages
        if (htRootPath == null) {
            htRootPath = new File(switchboard.getRootPath(), switchboard.getConfig("htRootPath","htroot"));
            if (!(htRootPath.exists())) htRootPath.mkdir();
        }
        
        // create a htDocsPath: user defined pages
        if (htDocsPath == null) {
            htDocsPath = new File(switchboard.getRootPath(), switchboard.getConfig("htDocsPath", "htdocs"));
            if (!(htDocsPath.exists())) htDocsPath.mkdir();
        }
        
        // create a htTemplatePath
        if (htTemplatePath == null) {
            htTemplatePath = new File(switchboard.getRootPath(), switchboard.getConfig("htTemplatePath","htroot/env/templates"));
            if (!(htTemplatePath.exists())) htTemplatePath.mkdir();
        }
        if (templates == null) templates = loadTemplates(htTemplatePath);
        
        // create htLocaleDefault, htLocalePath
        if (htDefaultPath == null) htDefaultPath = new File(switchboard.getRootPath(), switchboard.getConfig("htDefaultPath","htroot"));
        if (htLocalePath == null) htLocalePath = new File(switchboard.getRootPath(), switchboard.getConfig("htLocalePath","htroot/locale"));
        //htLocaleSelection = switchboard.getConfig("htLocaleSelection","default");
        
        // create a class loader
        if (provider == null) {
            provider = new serverClassLoader(/*this.getClass().getClassLoader()*/);
            // debug
            /*
             Package[] ps = ((cachedClassLoader) provider).packages();
             for (int i = 0; i < ps.length; i++) System.out.println("PACKAGE IN PROVIDER: " + ps[i].toString());
             */
        }
        
        // initialise an message digest for Content-MD5 support ...
        try {
            this.md5Digest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            serverLog.logWarning("HTTPDFileHandler", "Content-MD5 support not availabel ...");
        }
        
        serverLog.logSystem("HTTPDFileHandler", "File Handler Initialized");
    }
    
//    private void textMessage(OutputStream out, int retcode, String body) throws IOException {
//        httpd.sendRespondHeader(
//                this.connectionProperties,  // the connection properties 
//                out,                        // the output stream
//                "HTTP/1.1",                 // the http version that should be used
//                retcode,                    // the http status code
//                null,                       // the http status message
//                "text/plain",               // the mimetype
//                body.length(),              // the content length
//                httpc.nowDate(),            // the modification date
//                null,                       // the expires date
//                null,                       // cookies
//                null,                       // content encoding
//                null);                      // transfer encoding
//        out.write(body.getBytes());
//        out.flush();
//    }
    
    private httpHeader getDefaultHeaders() {
        httpHeader headers = new httpHeader();
        headers.put(httpHeader.SERVER, "AnomicHTTPD (www.anomic.de)");
        headers.put(httpHeader.DATE, httpc.dateString(httpc.nowDate()));
        headers.put(httpHeader.PRAGMA, "no-cache");         
        return headers;
    }
    
    public void doGet(Properties conProp, httpHeader requestHeader, OutputStream response) throws IOException {
        doResponse(conProp, requestHeader, response, null);
    }
    
    public void doHead(Properties conProp, httpHeader requestHeader, OutputStream response) throws IOException {
        doResponse(conProp, requestHeader, response, null);
    }
    
    public void doPost(Properties conProp, httpHeader requestHeader, OutputStream response, PushbackInputStream body) throws IOException {
        doResponse(conProp, requestHeader, response, body);
    }
    
    public void doResponse(Properties conProp, httpHeader requestHeader, OutputStream out, PushbackInputStream body) throws IOException {
        
        this.connectionProperties = conProp;
        
        // getting some connection properties
        String method     = conProp.getProperty(httpd.CONNECTION_PROP_METHOD);
        String path       = conProp.getProperty(httpd.CONNECTION_PROP_PATH);
        String argsString = conProp.getProperty(httpd.CONNECTION_PROP_ARGS); // is null if no args were given
        String httpVersion= conProp.getProperty(httpd.CONNECTION_PROP_HTTP_VER);
        String url = "http://" + requestHeader.get(httpHeader.HOST,"localhost") + path;
        
        // check hack attacks in path
        if (path.indexOf("..") >= 0) {
            httpd.sendRespondHeader(conProp,out,httpVersion,403,getDefaultHeaders());
            return;
        }
        
        // check permission/granted access
        String authorization = (String) requestHeader.get(httpHeader.AUTHORIZATION);
        String adminAccountBase64MD5 = switchboard.getConfig("adminAccountBase64MD5", "");
        if ((path.endsWith("_p.html")) && (adminAccountBase64MD5.length() != 0)) {
            // authentication required
            if (authorization == null) {
                // no authorization given in response. Ask for that
                httpHeader headers = getDefaultHeaders();
                headers.put(httpHeader.WWW_AUTHENTICATE,"Basic realm=\"admin log-in\"");
                httpd.sendRespondHeader(conProp,out,httpVersion,401,headers);
                return;
            } else if (adminAccountBase64MD5.equals(serverCodings.standardCoder.encodeMD5Hex(authorization.trim().substring(6)))) {
                // remove brute-force flag
                serverCore.bfHost.remove(conProp.getProperty("CLIENTIP"));
            } else {
                // a wrong authentication was given. Ask again
                String clientIP = conProp.getProperty("CLIENTIP", "unknown-host");
                serverLog.logInfo("HTTPD", "Wrong log-in for account 'admin' in http file handler for path '" + path + "' from host '" + clientIP + "'");
                Integer attempts = (Integer) serverCore.bfHost.get(clientIP);
                if (attempts == null)
                    serverCore.bfHost.put(clientIP, new Integer(1));
                else
                    serverCore.bfHost.put(clientIP, new Integer(attempts.intValue() + 1));

                httpHeader headers = getDefaultHeaders();
                headers.put(httpHeader.WWW_AUTHENTICATE,"Basic realm=\"admin log-in\"");
                httpd.sendRespondHeader(conProp,out,httpVersion,401,headers);
                return;
            }
        }
        
        // handle bfHost in case we have authentified correctly
        if ((authorization != null) &&
            (adminAccountBase64MD5.length() != 0) &&
            (adminAccountBase64MD5.equals(serverCodings.standardCoder.encodeMD5Hex(authorization.trim().substring(6))))) {
            // remove brute-force flag
            serverCore.bfHost.remove(conProp.getProperty("CLIENTIP"));
        }
        
        // parse arguments
        serverObjects args = new serverObjects();
        int argc;
        if (argsString == null) {
            // no args here, maybe a POST with multipart extension
            int length;
            //System.out.println("HEADER: " + requestHeader.toString()); // DEBUG
            if ((method.equals(httpHeader.METHOD_POST)) &&
                    (requestHeader.containsKey(httpHeader.CONTENT_LENGTH))) {
                // if its a POST, it can be either multipart or as args in the body
                length = Integer.parseInt((String) requestHeader.get(httpHeader.CONTENT_LENGTH));
                if ((requestHeader.containsKey(httpHeader.CONTENT_TYPE)) &&
                        (((String) requestHeader.get(httpHeader.CONTENT_TYPE)).toLowerCase().startsWith("multipart"))) {
                    // parse multipart
                    HashMap files = httpd.parseMultipart(requestHeader, args, body, length);
                    // integrate these files into the args
                    if (files != null) {
                        Iterator fit = files.entrySet().iterator();
                        Map.Entry entry;
                        while (fit.hasNext()) {
                            entry = (Map.Entry) fit.next();
                            args.put(((String) entry.getKey()) + "$file", entry.getValue());
                        }
                    }
                    argc = Integer.parseInt((String) requestHeader.get("ARGC"));
                } else {
                    // parse args in body
                    argc = httpd.parseArgs(args, body, length);
                }
            } else {
                // no args
                argsString = null;
                args = null;
                argc = 0;
            }
        } else {
            // simple args in URL (stuff after the "?")
            argc = httpd.parseArgs(args, argsString);
        }
        
        //if (args != null) System.out.println("***ARGS=" + args.toString()); // DEBUG
        
        // check for cross site scripting - attacks in request arguments
        if (argc > 0) {
            // check all values for occurrences of script values
            Enumeration e = args.elements(); // enumeration of values
            Object val;
            while (e.hasMoreElements()) {
                val = e.nextElement();
                if ((val != null) && (val instanceof String) && (((String) val).indexOf("<script") >= 0)) {
                    // deny request
                    httpd.sendRespondError(conProp,out,4,403,null,"bad post values",null);
                    //httpd.sendRespondHeader(conProp,out,httpVersion,403,"bad post values",0);
                    return;
                }
            }
        }
        
        // we are finished with parsing
        // the result of value hand-over is in args and argc
        if (path.length() == 0) {
            httpd.sendRespondError(conProp,out,4,400,null,"Bad Request",null);
            // textMessage(out, 400, "Bad Request\r\n");
            out.flush();
            return;
        }
        
        Date filedate;
        File rc = null;
        try {
            // locate the file
            if (!(path.startsWith("/"))) {
                // attach leading slash
                path = "/" + path;
            }
            
            // find defaults
            String testpath = path;
            if (path.endsWith("/")) {
                File file;
                // attach default file name
                for (int i = 0; i < defaultFiles.length; i++) {
                    testpath = path + defaultFiles[i];
                    file = new File(htDefaultPath, testpath);
                    if (!(file.exists())) file = new File(htDocsPath, testpath);
                    if (file.exists()) {path = testpath; break;}
                }
            }
            
            // find locales or alternatives in htDocsPath
            File defaultFile = new File(htDefaultPath, path);
            File localizedFile = defaultFile;
            if (defaultFile.exists()) {
                // look if we have a localization of that file
                String htLocaleSelection = switchboard.getConfig("htLocaleSelection","default");
                if (!(htLocaleSelection.equals("default"))) {
                    File localePath = new File(htLocalePath, htLocaleSelection + "/" + path);
                    if (localePath.exists()) localizedFile = localePath;
                }
            } else {
                // try to find that file in the htDocsPath
                defaultFile = new File(htDocsPath, path);
                localizedFile = defaultFile;
            }
                       
            if ((localizedFile.exists()) && (localizedFile.canRead())) {
                // we have found a file that can be written to the client
                // if this file uses templates, then we use the template
                // re-write - method to create an result
                serverObjects tp = new serverObjects();
                filedate = new Date(localizedFile.lastModified());
                String mimeType = this.mimeTable.getProperty(conProp.getProperty("EXT",""),"text/html");
                byte[] result;
                boolean zipContent = requestHeader.acceptGzip() && httpd.shallTransportZipped("." + conProp.getProperty("EXT",""));
                String md5String = null;
                if (path.endsWith("html") || 
                        path.endsWith("xml") || 
                        path.endsWith("rss") || 
                        path.endsWith("csv") ||
                        path.endsWith("pac")) {
                    rc = rewriteClassFile(defaultFile);
                    if (rc != null) {
                        // CGI-class: call the class to create a property for rewriting
                        try {
                            requestHeader.put("CLIENTIP", conProp.getProperty("CLIENTIP"));
                            requestHeader.put("PATH", path);
                            // in case that there are no args given, args = null or empty hashmap
                            tp = (serverObjects) rewriteMethod(rc).invoke(null, new Object[] {requestHeader, args, switchboard});
                            // if no args given , then tp will be an empty Hashtable object (not null)
                            if (tp == null) tp = new serverObjects();
                            // check if the servlets requests authentification
                            if (tp.containsKey("AUTHENTICATE")) {
                                // handle brute-force protection
                                if (authorization != null) {
                                    String clientIP = conProp.getProperty("CLIENTIP", "unknown-host");
                                    serverLog.logInfo("HTTPD", "dynamic log-in for account 'admin' in http file handler for path '" + path + "' from host '" + clientIP + "'");
                                    Integer attempts = (Integer) serverCore.bfHost.get(clientIP);
                                    if (attempts == null)
                                        serverCore.bfHost.put(clientIP, new Integer(1));
                                    else
                                        serverCore.bfHost.put(clientIP, new Integer(attempts.intValue() + 1));
                                }
                                // send authentication request to browser
                                httpHeader headers = getDefaultHeaders();
                                headers.put(httpHeader.WWW_AUTHENTICATE,"Basic realm=\"" + tp.get("AUTHENTICATE", "") + "\"");
                                httpd.sendRespondHeader(conProp,out,httpVersion,401,headers);
                                return;
                            }
                            // add the application version to every rewrite table
                            tp.put("version", switchboard.getConfig("version", ""));
                            tp.put("uptime", ((System.currentTimeMillis() - Long.parseLong(switchboard.getConfig("startupTime","0"))) / 1000) / 60); // uptime in minutes
                            //System.out.println("respond props: " + ((tp == null) ? "null" : tp.toString())); // debug
                        } catch (InvocationTargetException e) {
                            this.theLogger.logError("INTERNAL ERROR: " + e.toString() + ":" +
                                    e.getMessage() +
                                    " target exception at " + rc + ": " +
                                    e.getTargetException().toString() + ":" +
                                    e.getTargetException().getMessage(),e);
                            rc = null;
                        }
                        filedate = new Date(System.currentTimeMillis());
                    }
                    // read templates
                    tp.putAll(templates);
                    // rewrite the file
                    ByteArrayOutputStream o = null;
                    FileInputStream fis = null;
                    GZIPOutputStream zippedOut = null;
                    try {
                        o = new ByteArrayOutputStream();
                        if (zipContent) zippedOut = new GZIPOutputStream(o);
                        fis = new FileInputStream(localizedFile);
                        httpTemplate.writeTemplate(fis, (zipContent) ? (OutputStream)zippedOut: (OutputStream)o, tp, "-UNRESOLVED_PATTERN-".getBytes());
                        if (zipContent) {
                            zippedOut.finish();
                            zippedOut.flush();
                            zippedOut.close();
                            zippedOut = null;
                        }
                        result = o.toByteArray();
                        
                        if (this.md5Digest != null) {
                            this.md5Digest.reset();
                            this.md5Digest.update(result);
                            byte[] digest = this.md5Digest.digest();
                            StringBuffer digestString = new StringBuffer();
                            for ( int i = 0; i < digest.length; i++ )
                                digestString.append(Integer.toHexString( digest[i]&0xff));

                            md5String = digestString.toString();
                        }                        
                    } finally {
                        if (zippedOut != null) try {zippedOut.close();} catch(Exception e) {}
                        if (o != null) try {o.close(); o = null;} catch(Exception e) {}
                        if (fis != null) try {fis.close();} catch(Exception e) {}
                    }
                    
                } else { // no html                    
                    // write the file to the client
                    result = (zipContent)? serverFileUtils.readAndZip(localizedFile) : serverFileUtils.read(localizedFile);
                    
                    // check mime type again using the result array: these are 'magics'
//                    if (serverByteBuffer.equals(result, 1, "PNG".getBytes())) mimeType = mimeTable.getProperty("png","text/html");
//                    else if (serverByteBuffer.equals(result, 0, "GIF89".getBytes())) mimeType = mimeTable.getProperty("gif","text/html");
//                    else if (serverByteBuffer.equals(result, 6, "JFIF".getBytes())) mimeType = mimeTable.getProperty("jpg","text/html");
                    //System.out.print("MAGIC:"); for (int i = 0; i < 10; i++) System.out.print(Integer.toHexString((int) result[i]) + ","); System.out.println();            
                }
                
                // write the array to the client
                httpd.sendRespondHeader(this.connectionProperties, out, "HTTP/1.1", 200, null, mimeType, result.length, filedate, null, null, (zipContent)?"gzip":null, null);
                Thread.currentThread().sleep(200); // this solved the message problem (!!)
                serverFileUtils.write(result, out);
            } else {
                httpd.sendRespondError(conProp,out,3,404,"File not Found",null,null);
                return;
            }
        } catch (Exception e) {     
            try {
                // doing some errorhandling ...
                int httpStatusCode = 400; 
                String httpStatusText = null; 
                StringBuffer errorMessage = new StringBuffer(); 
                Exception errorExc = null;            
                
                String errorMsg = e.getMessage();
                if (
                        (e instanceof InterruptedException) ||
                        ((errorMsg != null) && (errorMsg.startsWith("Socket closed")) && (Thread.currentThread().isInterrupted()))
                   ) {
                    errorMessage.append("Interruption detected while processing query.");
                    httpStatusCode = 503;
                } else {
                    if ((errorMsg != null) && 
                        (
                           errorMsg.startsWith("Broken pipe") || 
                           errorMsg.startsWith("Connection reset") ||
                           errorMsg.startsWith("Software caused connection abort")                           
                       )) {
                        // client closed the connection, so we just end silently
                        errorMessage.append("Client unexpectedly closed connection while processing query.");
                    } else if ((errorMsg != null) && (errorMsg.startsWith("Connection timed out"))) {
                        errorMessage.append("Connection timed out.");
                    } else {
                        errorMessage.append("Unexpected error while processing query.");
                        httpStatusCode = 500;
                        errorExc = e;
                    }
                }
                
                errorMessage.append("\nSession: ").append(Thread.currentThread().getName())
                            .append("\nQuery:   ").append(path)
                            .append("\nClient:  ").append(conProp.getProperty(httpd.CONNECTION_PROP_CLIENTIP,"unknown")) 
                            .append("\nReason:  ").append(e.toString());    
                
                if (!conProp.containsKey(httpd.CONNECTION_PROP_PROXY_RESPOND_HEADER)) {
                    // sending back an error message to the client 
                    // if we have not already send an http header
                    httpd.sendRespondError(conProp,out, 4, httpStatusCode, httpStatusText, errorMessage.toString(),errorExc);
                } else {
                    // otherwise we close the connection
                    this.forceConnectionClose();
                }    
                
                // if it is an unexpected error we log it 
                if (httpStatusCode == 500) {
                    this.theLogger.logWarning(errorMessage.toString(),e);
                }
                
            } catch (Exception ee) {
                this.forceConnectionClose();
            }            
            
        } finally {
            try {out.flush();}catch (Exception e) {}
            if (!(requestHeader.get(httpHeader.CONNECTION, "close").equals("keep-alive"))) {
                // wait a little time until everything closes so that clients can read from the streams/sockets
                try {Thread.sleep(1000);} catch (InterruptedException e) {}
            }
        }
    }
    
    private void forceConnectionClose() {
        if (this.connectionProperties != null) {
            this.connectionProperties.setProperty(httpd.CONNECTION_PROP_PERSISTENT,"close");            
        }
    }

    private static HashMap loadTemplates(File path) {
        // reads all templates from a path
        // we use only the folder from the given file path
        HashMap result = new HashMap();
        if (path == null) return result;
        if (!(path.isDirectory())) path = path.getParentFile();
        if ((path == null) || (!(path.isDirectory()))) return result;
        String[] templates = path.list();
        int c;
        for (int i = 0; i < templates.length; i++) {
            if (templates[i].endsWith(".template")) 
                try {
                    //System.out.println("TEMPLATE " + templates[i].substring(0, templates[i].length() - 9) + ": " + new String(buf, 0, c));
                    result.put(templates[i].substring(0, templates[i].length() - 9),
                            new String(serverFileUtils.read(new File(path, templates[i]))));
                } catch (Exception e) {}
        }
        return result;
    }
    
    private File rewriteClassFile(File template) {
        try {
            String f = template.getCanonicalPath();
            int p = f.lastIndexOf(".");
            if (p < 0) return null;
            f = f.substring(0, p) + ".class";
            //System.out.println("constructed class path " + f);
            File cf = new File(f);
            if (cf.exists()) return cf;
            return null;
        } catch (IOException e) {
            return null;
        }
    }
    
    private Method rewriteMethod(File classFile) {
        Method m = null;
        // now make a class out of the stream
        try {
            //System.out.println("**DEBUG** loading class file " + classFile);
            Class c = provider.loadClass(classFile);
            Class[] params = new Class[] {
                    Class.forName("de.anomic.http.httpHeader"),
                    Class.forName("de.anomic.server.serverObjects"),
                    Class.forName("de.anomic.server.serverSwitch")};
            m = c.getMethod("respond", params);
        } catch (ClassNotFoundException e) {
            System.out.println("INTERNAL ERROR: class " + classFile + " is missing:" + e.getMessage()); 
        } catch (NoSuchMethodException e) {
            System.out.println("INTERNAL ERROR: method respond not found in class " + classFile + ": " + e.getMessage());
        }
        //System.out.println("found method: " + m.toString());
        return m;
    }
    
    public void doConnect(Properties conProp, httpHeader requestHeader, InputStream clientIn, OutputStream clientOut) {
        throw new UnsupportedOperationException();
    }
    
}