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package jnlp.sample.servlet;

import java.util.*;
import java.util.regex.*;
import java.net.*;
import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;
import javax.xml.parsers.*;
import org.xml.sax.*;
import javax.xml.transform.*;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import org.w3c.dom.*;

/* The JNLP file handler implements a class that keeps
 * track of JNLP files and their specializations
 */
public class JnlpFileHandler {
    private static final String JNLP_MIME_TYPE = "application/x-java-jnlp-file";
    private static final String HEADER_LASTMOD = "Last-Modified";

    private ServletContext _servletContext;
    private Logger _log = null;
    private HashMap _jnlpFiles = null;

    /** Initialize JnlpFileHandler for the specific ServletContext */
    public JnlpFileHandler(ServletContext servletContext, Logger log) {
        _servletContext = servletContext;
        _log = log;
        _jnlpFiles = new HashMap();
    }

    private static class JnlpFileEntry {
        // Response
        DownloadResponse _response;
        // Keeps track of cache is out of date
        private long   _lastModified;

        // Constructor
        JnlpFileEntry(DownloadResponse response, long lastmodfied) {
            _response = response;
            _lastModified = lastmodfied;
        }

        public DownloadResponse getResponse() { return _response; }
        long getLastModified() { return _lastModified; }
    }

    /* Main method to lookup an entry */
    public synchronized DownloadResponse getJnlpFile(JnlpResource jnlpres, DownloadRequest dreq)
        throws IOException {
        String path = jnlpres.getPath();
        URL resource = jnlpres.getResource();
        long lastModified = jnlpres.getLastModified();


        _log.addDebug("lastModified: " + lastModified + " " + new Date(lastModified));
        if (lastModified == 0) {
            _log.addWarning("servlet.log.warning.nolastmodified", path);
        }

        // fix for 4474854:  use the request URL as key to look up jnlp file
        // in hash map
        String reqUrl = HttpUtils.getRequestURL(dreq.getHttpRequest()).toString();

        // Check if entry already exist in HashMap
        JnlpFileEntry jnlpFile = (JnlpFileEntry)_jnlpFiles.get(reqUrl);

        if (jnlpFile != null && jnlpFile.getLastModified() == lastModified) {
            // Entry found in cache, so return it
            return jnlpFile.getResponse();
        }

        // Read information from WAR file
        long timeStamp = lastModified;
        String mimeType = _servletContext.getMimeType(path);
        if (mimeType == null) mimeType = JNLP_MIME_TYPE;

        StringBuffer jnlpFileTemplate = new StringBuffer();
        URLConnection conn = resource.openConnection();
        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
        String line = br.readLine();
        if (line != null && line.startsWith("TS:")) {
            timeStamp = parseTimeStamp(line.substring(3));
            _log.addDebug("Timestamp: " + timeStamp + " " + new Date(timeStamp));
            if (timeStamp == 0) {
                _log.addWarning("servlet.log.warning.notimestamp", path);
                timeStamp = lastModified;
            }
            line = br.readLine();
        }
        while(line != null) {
            jnlpFileTemplate.append(line);
            line = br.readLine();
        }

        String jnlpFileContent = specializeJnlpTemplate(dreq.getHttpRequest(), path, jnlpFileTemplate.toString());

        // Convert to bytes as a UTF-8 encoding
        byte[] byteContent = jnlpFileContent.getBytes("UTF-8");

        // Create entry
        DownloadResponse resp = DownloadResponse.getFileDownloadResponse(byteContent,
                                                                         mimeType,
                                                                         timeStamp,
                                                                         jnlpres.getReturnVersionId());
        jnlpFile = new JnlpFileEntry(resp, lastModified);
        _jnlpFiles.put(reqUrl, jnlpFile);

        return resp;
    }

    /* Main method to lookup an entry (NEW for JavaWebStart 1.5+) */
    public synchronized DownloadResponse getJnlpFileEx(JnlpResource jnlpres, DownloadRequest dreq)
        throws IOException {
        String path = jnlpres.getPath();
        URL resource = jnlpres.getResource();
        long lastModified = jnlpres.getLastModified();


        _log.addDebug("lastModified: " + lastModified + " " + new Date(lastModified));
        if (lastModified == 0) {
            _log.addWarning("servlet.log.warning.nolastmodified", path);
        }

        // fix for 4474854:  use the request URL as key to look up jnlp file
        // in hash map
        String reqUrl = HttpUtils.getRequestURL(dreq.getHttpRequest()).toString();
        // SQE: To support query string, we changed the hash key from Request URL to (Request URL + query string)
        if (dreq.getQuery() != null)
            reqUrl += dreq.getQuery();

        // Check if entry already exist in HashMap
        JnlpFileEntry jnlpFile = (JnlpFileEntry)_jnlpFiles.get(reqUrl);

        if (jnlpFile != null && jnlpFile.getLastModified() == lastModified) {
            // Entry found in cache, so return it
            return jnlpFile.getResponse();
        }

        // Read information from WAR file
        long timeStamp = lastModified;
        String mimeType = _servletContext.getMimeType(path);
        if (mimeType == null) mimeType = JNLP_MIME_TYPE;

        StringBuffer jnlpFileTemplate = new StringBuffer();
        URLConnection conn = resource.openConnection();
        BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream(), "UTF-8"));
        String line = br.readLine();
        if (line != null && line.startsWith("TS:")) {
            timeStamp = parseTimeStamp(line.substring(3));
            _log.addDebug("Timestamp: " + timeStamp + " " + new Date(timeStamp));
            if (timeStamp == 0) {
                _log.addWarning("servlet.log.warning.notimestamp", path);
                timeStamp = lastModified;
            }
            line = br.readLine();
        }
        while(line != null) {
            jnlpFileTemplate.append(line);
            line = br.readLine();
        }

        String jnlpFileContent = specializeJnlpTemplate(dreq.getHttpRequest(), path, jnlpFileTemplate.toString());

        /* SQE: We need to add query string back to href in jnlp file. We also need to handle JRE requirement for
         * the test. We reconstruct the xml DOM object, modify the value, then regenerate the jnlpFileContent.
         */
        String query = dreq.getQuery();
        String testJRE = dreq.getTestJRE();
        _log.addDebug("Double check query string: " + query);
        // For backward compatibility: Always check if the href value exists.
        // Bug 4939273: We will retain the jnlp template structure and will NOT add href value. Above old
        // approach to always check href value caused some test case not run.
        if (query != null) {
            byte [] cb = jnlpFileContent.getBytes("UTF-8");
            ByteArrayInputStream bis = new ByteArrayInputStream(cb);
            try {
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();
                Document document = builder.parse(bis);
                if (document != null && document.getNodeType() == Node.DOCUMENT_NODE) {
                    boolean modified = false;
                    Element root = document.getDocumentElement();

                    if (root.hasAttribute("href") && query != null) {
                        String href = root.getAttribute("href");
                        root.setAttribute("href", href + "?" + query);
                        modified = true;
                    }
                    // Update version value for j2se tag
                    if (testJRE != null) {
                        NodeList j2seNL = root.getElementsByTagName("j2se");
                        if (j2seNL != null) {
                            Element j2se = (Element) j2seNL.item(0);
                            String ver = j2se.getAttribute("version");
                            if (ver.length() > 0) {
                                j2se.setAttribute("version", testJRE);
                                modified = true;
                            }
                        }
                    }
                    TransformerFactory tFactory = TransformerFactory.newInstance();
                    Transformer transformer = tFactory.newTransformer();
                    DOMSource source = new DOMSource(document);
                    StringWriter sw = new StringWriter();
                    StreamResult result = new StreamResult(sw);
                    transformer.transform(source, result);
                    jnlpFileContent = sw.toString();
                    _log.addDebug("Converted jnlpFileContent: " + jnlpFileContent);
                    // Since we modified the file on the fly, we always update the timestamp value with current time
                    if (modified) {
                        timeStamp = new java.util.Date().getTime();
                        _log.addDebug("Last modified on the fly:  " + timeStamp);
                    }
                }
            } catch (Exception e) {
                _log.addDebug(e.toString(), e);
            }
        }

        // Convert to bytes as a UTF-8 encoding
        byte[] byteContent = jnlpFileContent.getBytes("UTF-8");

        // Create entry
        DownloadResponse resp = DownloadResponse.getFileDownloadResponse(byteContent,
                                                                         mimeType,
                                                                         timeStamp,
                                                                         jnlpres.getReturnVersionId());
        jnlpFile = new JnlpFileEntry(resp, lastModified);
        _jnlpFiles.put(reqUrl, jnlpFile);

        return resp;
    }

    /* This method performs the following substituations
     *  $$name
     *  $$codebase
     *  $$context
     */
    private String specializeJnlpTemplate(HttpServletRequest request, String respath, String jnlpTemplate) {
        String urlprefix = getUrlPrefix(request);
        int idx = respath.lastIndexOf('/'); //
        String name = respath.substring(idx + 1);    // Exclude /
        String codebase = respath.substring(0, idx + 1); // Include /
        jnlpTemplate = substitute(jnlpTemplate, "$$name",  name);
        // fix for 5039951: Add $$hostname macro
        jnlpTemplate = substitute(jnlpTemplate, "$$hostname",
                                  request.getServerName());
        jnlpTemplate = substitute(jnlpTemplate, "$$codebase",  urlprefix + request.getContextPath() + codebase);
        jnlpTemplate = substitute(jnlpTemplate, "$$context", urlprefix + request.getContextPath());
        // fix for 6256326: add $$site macro to sample jnlp servlet
        jnlpTemplate = substitute(jnlpTemplate, "$$site", urlprefix);
        return jnlpTemplate;
    }

    // This code is heavily inspired by the stuff in HttpUtils.getRequestURL
    private String getUrlPrefix(HttpServletRequest req) {
        StringBuffer url = new StringBuffer();
        String scheme = req.getScheme();
        int port = req.getServerPort();
        url.append(scheme);             // http, https
        url.append("://");
        url.append(req.getServerName());
        if ((scheme.equals("http") && port != 80)
            || (scheme.equals("https") && port != 443)) {
            url.append(':');
            url.append(req.getServerPort());
        }
        return url.toString();
    }

    private String substitute(String target, String key, String value) {
        int start = 0;
        do {
            int idx = target.indexOf(key, start);
            if (idx == -1) return target;
            target =  target.substring(0, idx) + value + target.substring(idx + key.length());
            start = idx + value.length();
        } while(true);
    }

    /** Parses a ISO 8601 Timestamp. The format of the timestamp is:
     *
     *   YYYY-MM-DD hh:mm:ss  or   YYYYMMDDhhmmss
     *
     * Hours (hh) is in 24h format. ss are optional. Time are by default relative
     * to the current timezone. Timezone information can be specified
     * by:
     *
     *    - Appending a 'Z', e.g., 2001-12-19 12:00Z
     *    - Appending +hh:mm, +hhmm, +hh, -hh:mm -hhmm, -hh to
     *      indicate that the locale timezone used is either the specified
     *      amound before or after GMT. For example,
     *
     *           12:00Z = 13:00+1:00 = 0700-0500
     *
     *  The method returns 0 if it cannot pass the string. Otherwise, it is
     *  the number of milliseconds size sometime in 1969.
     */
    private long parseTimeStamp(String timestamp) {
        int YYYY = 0;
        int MM = 0;
        int DD = 0;
        int hh = 0;
        int mm = 0;
        int ss = 0;

        timestamp = timestamp.trim();
        try {
            // Check what format is used
            if (matchPattern("####-##-## ##:##", timestamp)) {
                YYYY = getIntValue(timestamp, 0, 4);
                MM = getIntValue(timestamp, 5, 7);
                DD = getIntValue(timestamp, 8, 10);
                hh = getIntValue(timestamp, 11, 13);
                mm = getIntValue(timestamp, 14, 16);
                timestamp = timestamp.substring(16);
                if (matchPattern(":##", timestamp)) {
                    ss = getIntValue(timestamp, 1, 3);
                    timestamp = timestamp.substring(3);
                }
            } else if (matchPattern("############", timestamp)) {
                YYYY = getIntValue(timestamp, 0, 4);
                MM = getIntValue(timestamp, 4, 6);
                DD = getIntValue(timestamp, 6, 8);
                hh = getIntValue(timestamp, 8, 10);
                mm = getIntValue(timestamp, 10, 12);
                timestamp = timestamp.substring(12);
                if (matchPattern("##", timestamp)) {
                    ss = getIntValue(timestamp, 0, 2);
                    timestamp = timestamp.substring(2);
                }
            } else {
                // Unknown format
                return 0;
            }
        } catch(NumberFormatException e) {
            // Bad number
            return 0;
        }

        String timezone = null;
        // Remove timezone information
        timestamp = timestamp.trim();
        if (timestamp.equalsIgnoreCase("Z")) {
            timezone ="GMT";
        } else if (timestamp.startsWith("+") || timestamp.startsWith("-")) {
            timezone = "GMT" + timestamp;
        }

        if (timezone == null) {
            // Date is relative to current locale
            Calendar cal = Calendar.getInstance();
            cal.set(YYYY, MM - 1, DD, hh, mm, ss);
            return cal.getTime().getTime();
        } else {
            // Date is relative to a timezone
            Calendar cal = Calendar.getInstance(TimeZone.getTimeZone(timezone));
            cal.set(YYYY, MM - 1, DD, hh, mm, ss);
            return cal.getTime().getTime();
        }
    }

    private int getIntValue(String key, int start, int end) {
        return Integer.parseInt(key.substring(start, end));
    }

    private boolean matchPattern(String pattern, String key) {
        // Key must be longer than pattern
        if (key.length() < pattern.length()) return false;
        for(int i = 0; i < pattern.length(); i++) {
            char format = pattern.charAt(i);
            char ch = key.charAt(i);
            if (!((format == '#' && Character.isDigit(ch)) || (format == ch))) {
                return false;
            }
        }
        return true;
    }
}
