//
   //  ========================================================================
   //  Copyright (c) 1995-2016 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.servlet;
  
  import static org.eclipse.jetty.http.GzipHttpContent.ETAG_GZIP_QUOTE;
  import static org.eclipse.jetty.http.GzipHttpContent.removeGzipFromETag;
  
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.nio.ByteBuffer;
  import java.util.ArrayList;
  import java.util.Enumeration;
  import java.util.List;
  import java.util.StringTokenizer;
  
  import javax.servlet.AsyncContext;
  import javax.servlet.RequestDispatcher;
  import javax.servlet.ServletContext;
  import javax.servlet.ServletException;
  import javax.servlet.UnavailableException;
  import javax.servlet.http.HttpServlet;
  import javax.servlet.http.HttpServletRequest;
  import javax.servlet.http.HttpServletResponse;
  
  import org.eclipse.jetty.http.DateParser;
  import org.eclipse.jetty.http.GzipHttpContent;
  import org.eclipse.jetty.http.HttpContent;
  import org.eclipse.jetty.http.HttpField;
  import org.eclipse.jetty.http.HttpFields;
  import org.eclipse.jetty.http.HttpHeader;
  import org.eclipse.jetty.http.HttpMethod;
  import org.eclipse.jetty.http.MimeTypes;
  import org.eclipse.jetty.http.PathMap.MappedEntry;
  import org.eclipse.jetty.http.PreEncodedHttpField;
  import org.eclipse.jetty.http.ResourceHttpContent;
  import org.eclipse.jetty.io.WriterOutputStream;
  import org.eclipse.jetty.server.HttpOutput;
  import org.eclipse.jetty.server.InclusiveByteRange;
  import org.eclipse.jetty.server.Request;
  import org.eclipse.jetty.server.ResourceCache;
  import org.eclipse.jetty.server.ResourceContentFactory;
  import org.eclipse.jetty.server.Response;
  import org.eclipse.jetty.server.handler.ContextHandler;
  import org.eclipse.jetty.util.BufferUtil;
  import org.eclipse.jetty.util.Callback;
  import org.eclipse.jetty.util.IO;
  import org.eclipse.jetty.util.MultiPartOutputStream;
  import org.eclipse.jetty.util.QuotedStringTokenizer;
  import org.eclipse.jetty.util.URIUtil;
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.resource.Resource;
  import org.eclipse.jetty.util.resource.ResourceCollection;
  import org.eclipse.jetty.util.resource.ResourceFactory;
  
  
  /** 
   * The default servlet.
   * <p>
   * This servlet, normally mapped to /, provides the handling for static
   * content, OPTION and TRACE methods for the context.
   * The following initParameters are supported, these can be set either
   * on the servlet itself or as ServletContext initParameters with a prefix
   * of org.eclipse.jetty.servlet.Default. :
   * <pre>
   *  acceptRanges      If true, range requests and responses are
   *                    supported
   *
   *  dirAllowed        If true, directory listings are returned if no
   *                    welcome file is found. Else 403 Forbidden.
   *
   *  welcomeServlets   If true, attempt to dispatch to welcome files
   *                    that are servlets, but only after no matching static
   *                    resources could be found. If false, then a welcome
   *                    file must exist on disk. If "exact", then exact
   *                    servlet matches are supported without an existing file.
   *                    Default is true.
   *
   *                    This must be false if you want directory listings,
  *                    but have index.jsp in your welcome file list.
  *
  *  redirectWelcome   If true, welcome files are redirected rather than
  *                    forwarded to.
  *
  *  gzip              If set to true, then static content will be served as
  *                    gzip content encoded if a matching resource is
  *                    found ending with ".gz"
  *
  *  resourceBase      Set to replace the context resource base
  *
  *  resourceCache     If set, this is a context attribute name, which the servlet
  *                    will use to look for a shared ResourceCache instance.
  *
  *  relativeResourceBase
  *                    Set with a pathname relative to the base of the
  *                    servlet context root. Useful for only serving static content out
  *                    of only specific subdirectories.
  *
  *  pathInfoOnly      If true, only the path info will be applied to the resourceBase
  *
  *  stylesheet	      Set with the location of an optional stylesheet that will be used
  *                    to decorate the directory listing html.
  *
  *  etags             If True, weak etags will be generated and handled.
  *
  *  maxCacheSize      The maximum total size of the cache or 0 for no cache.
  *  maxCachedFileSize The maximum size of a file to cache
  *  maxCachedFiles    The maximum number of files to cache
  *
  *  useFileMappedBuffer
  *                    If set to true, it will use mapped file buffer to serve static content
  *                    when using NIO connector. Setting this value to false means that
  *                    a direct buffer will be used instead of a mapped file buffer.
  *                    This is set to false by default by this class, but may be overridden
  *                    by eg webdefault.xml 
  *
  *  cacheControl      If set, all static content will have this value set as the cache-control
  *                    header.
  *                    
  * otherGzipFileExtensions
  *                    Other file extensions that signify that a file is gzip compressed. Eg ".svgz"
  *
  *
  * </pre>
  *
  */
 public class DefaultServlet extends HttpServlet implements ResourceFactory
 {
     private static final Logger LOG = Log.getLogger(DefaultServlet.class);
 
     private static final long serialVersionUID = 4930458713846881193L;
     
     private static final PreEncodedHttpField ACCEPT_RANGES = new PreEncodedHttpField(HttpHeader.ACCEPT_RANGES, "bytes");
     
     private ServletContext _servletContext;
     private ContextHandler _contextHandler;
 
     private boolean _acceptRanges=true;
     private boolean _dirAllowed=true;
     private boolean _welcomeServlets=false;
     private boolean _welcomeExactServlets=false;
     private boolean _redirectWelcome=false;
     private boolean _gzip=false;
     private boolean _pathInfoOnly=false;
     private boolean _etags=false;
 
     private Resource _resourceBase;
     private ResourceCache _cache;
     private HttpContent.Factory _contentFactory;
 
     private MimeTypes _mimeTypes;
     private String[] _welcomes;
     private Resource _stylesheet;
     private boolean _useFileMappedBuffer=false;
     private HttpField _cacheControl;
     private String _relativeResourceBase;
     private ServletHandler _servletHandler;
     private ServletHolder _defaultHolder;
     private List<String> _gzipEquivalentFileExtensions;
 
     /* ------------------------------------------------------------ */
     @Override
     public void init()
     throws UnavailableException
     {
         _servletContext=getServletContext();
         _contextHandler = initContextHandler(_servletContext);
 
         _mimeTypes = _contextHandler.getMimeTypes();
 
         _welcomes = _contextHandler.getWelcomeFiles();
         if (_welcomes==null)
             _welcomes=new String[] {"index.html","index.jsp"};
 
         _acceptRanges=getInitBoolean("acceptRanges",_acceptRanges);
         _dirAllowed=getInitBoolean("dirAllowed",_dirAllowed);
         _redirectWelcome=getInitBoolean("redirectWelcome",_redirectWelcome);
         _gzip=getInitBoolean("gzip",_gzip);
         _pathInfoOnly=getInitBoolean("pathInfoOnly",_pathInfoOnly);
 
         if ("exact".equals(getInitParameter("welcomeServlets")))
         {
             _welcomeExactServlets=true;
             _welcomeServlets=false;
         }
         else
             _welcomeServlets=getInitBoolean("welcomeServlets", _welcomeServlets);
 
         _useFileMappedBuffer=getInitBoolean("useFileMappedBuffer",_useFileMappedBuffer);
 
         _relativeResourceBase = getInitParameter("relativeResourceBase");
 
         String rb=getInitParameter("resourceBase");
         if (rb!=null)
         {
             if (_relativeResourceBase!=null)
                 throw new  UnavailableException("resourceBase & relativeResourceBase");
             try{_resourceBase=_contextHandler.newResource(rb);}
             catch (Exception e)
             {
                 LOG.warn(Log.EXCEPTION,e);
                 throw new UnavailableException(e.toString());
             }
         }
 
         String css=getInitParameter("stylesheet");
         try
         {
             if(css!=null)
             {
                 _stylesheet = Resource.newResource(css);
                 if(!_stylesheet.exists())
                 {
                     LOG.warn("!" + css);
                     _stylesheet = null;
                 }
             }
             if(_stylesheet == null)
             {
                 _stylesheet = Resource.newResource(this.getClass().getResource("/jetty-dir.css"));
             }
         }
         catch(Exception e)
         {
             LOG.warn(e.toString());
             LOG.debug(e);
         }
 
         String cc=getInitParameter("cacheControl");
         if (cc!=null)
             _cacheControl=new PreEncodedHttpField(HttpHeader.CACHE_CONTROL, cc);
 
         String resourceCache = getInitParameter("resourceCache");
         int max_cache_size=getInitInt("maxCacheSize", -2);
         int max_cached_file_size=getInitInt("maxCachedFileSize", -2);
         int max_cached_files=getInitInt("maxCachedFiles", -2);
         if (resourceCache!=null)
         {
             if (max_cache_size!=-1 || max_cached_file_size!= -2 || max_cached_files!=-2)
                 LOG.debug("ignoring resource cache configuration, using resourceCache attribute");
             if (_relativeResourceBase!=null || _resourceBase!=null)
                 throw new UnavailableException("resourceCache specified with resource bases");
             _cache=(ResourceCache)_servletContext.getAttribute(resourceCache);
 
             if (LOG.isDebugEnabled())
                 LOG.debug("Cache {}={}",resourceCache,_contentFactory);
         }
 
         _etags = getInitBoolean("etags",_etags);
 
         try
         {
             if (_cache==null && (max_cached_files!=-2 || max_cache_size!=-2 || max_cached_file_size!=-2))
             {
                 _cache = new ResourceCache(null,this,_mimeTypes,_useFileMappedBuffer,_etags,_gzip);
                 if (max_cache_size>=0)
                     _cache.setMaxCacheSize(max_cache_size);
                 if (max_cached_file_size>=-1)
                     _cache.setMaxCachedFileSize(max_cached_file_size);
                 if (max_cached_files>=-1)
                     _cache.setMaxCachedFiles(max_cached_files);
                 _servletContext.setAttribute(resourceCache==null?"resourceCache":resourceCache,_cache);
             }
         }
         catch (Exception e)
         {
             LOG.warn(Log.EXCEPTION,e);
             throw new UnavailableException(e.toString());
         }
 
         if (_cache!=null)
             _contentFactory=_cache;
         else
         {
             _contentFactory=new ResourceContentFactory(this,_mimeTypes,_gzip);
             if (resourceCache!=null)
                 _servletContext.setAttribute(resourceCache,_contentFactory);
         }
         
         _gzipEquivalentFileExtensions = new ArrayList<String>();
         String otherGzipExtensions = getInitParameter("otherGzipFileExtensions");
         if (otherGzipExtensions != null)
         {
             //comma separated list
             StringTokenizer tok = new StringTokenizer(otherGzipExtensions,",",false);
             while (tok.hasMoreTokens())
             {
                 String s = tok.nextToken().trim();
                 _gzipEquivalentFileExtensions.add((s.charAt(0)=='.'?s:"."+s));
             }
         }
         else
         {
             //.svgz files are gzipped svg files and must be served with Content-Encoding:gzip
             _gzipEquivalentFileExtensions.add(".svgz");   
         }
 
         _servletHandler= _contextHandler.getChildHandlerByClass(ServletHandler.class);
         for (ServletHolder h :_servletHandler.getServlets())
             if (h.getServletInstance()==this)
                 _defaultHolder=h;
 
         if (LOG.isDebugEnabled())
             LOG.debug("resource base = "+_resourceBase);
     }
 
     /**
      * Compute the field _contextHandler.<br>
      * In the case where the DefaultServlet is deployed on the HttpService it is likely that
      * this method needs to be overwritten to unwrap the ServletContext facade until we reach
      * the original jetty's ContextHandler.
      * @param servletContext The servletContext of this servlet.
      * @return the jetty's ContextHandler for this servletContext.
      */
     protected ContextHandler initContextHandler(ServletContext servletContext)
     {
         ContextHandler.Context scontext=ContextHandler.getCurrentContext();
         if (scontext==null)
         {
             if (servletContext instanceof ContextHandler.Context)
                 return ((ContextHandler.Context)servletContext).getContextHandler();
             else
                 throw new IllegalArgumentException("The servletContext " + servletContext + " " +
                     servletContext.getClass().getName() + " is not " + ContextHandler.Context.class.getName());
         }
         else
             return ContextHandler.getCurrentContext().getContextHandler();
     }
 
     /* ------------------------------------------------------------ */
     @Override
     public String getInitParameter(String name)
     {
         String value=getServletContext().getInitParameter("org.eclipse.jetty.servlet.Default."+name);
         if (value==null)
             value=super.getInitParameter(name);
         return value;
     }
 
     /* ------------------------------------------------------------ */
     private boolean getInitBoolean(String name, boolean dft)
     {
         String value=getInitParameter(name);
         if (value==null || value.length()==0)
             return dft;
         return (value.startsWith("t")||
                 value.startsWith("T")||
                 value.startsWith("y")||
                 value.startsWith("Y")||
                 value.startsWith("1"));
     }
 
     /* ------------------------------------------------------------ */
     private int getInitInt(String name, int dft)
     {
         String value=getInitParameter(name);
         if (value==null)
             value=getInitParameter(name);
         if (value!=null && value.length()>0)
             return Integer.parseInt(value);
         return dft;
     }
 
     /* ------------------------------------------------------------ */
     /** get Resource to serve.
      * Map a path to a resource. The default implementation calls
      * HttpContext.getResource but derived servlets may provide
      * their own mapping.
      * @param pathInContext The path to find a resource for.
      * @return The resource to serve.
      */
     @Override
     public Resource getResource(String pathInContext)
     {
         Resource r=null;
         if (_relativeResourceBase!=null)
             pathInContext=URIUtil.addPaths(_relativeResourceBase,pathInContext);
 
         try
         {
             if (_resourceBase!=null)
             {
                 r = _resourceBase.addPath(pathInContext);
                 if (!_contextHandler.checkAlias(pathInContext,r))
                     r=null;
             }
             else if (_servletContext instanceof ContextHandler.Context)
             {
                 r = _contextHandler.getResource(pathInContext);
             }
             else
             {
                 URL u = _servletContext.getResource(pathInContext);
                 r = _contextHandler.newResource(u);
             }
 
             if (LOG.isDebugEnabled())
                 LOG.debug("Resource "+pathInContext+"="+r);
         }
         catch (IOException e)
         {
             LOG.ignore(e);
         }
 
         if((r==null || !r.exists()) && pathInContext.endsWith("/jetty-dir.css"))
             r=_stylesheet;
 
         return r;
     }
 
     /* ------------------------------------------------------------ */
     @Override
     protected void doGet(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, IOException
     {
         String servletPath=null;
         String pathInfo=null;
         Enumeration<String> reqRanges = null;
         boolean included =request.getAttribute(RequestDispatcher.INCLUDE_REQUEST_URI)!=null;
         if (included)
         {
             servletPath=(String)request.getAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH);
             pathInfo=(String)request.getAttribute(RequestDispatcher.INCLUDE_PATH_INFO);
             if (servletPath==null)
             {
                 servletPath=request.getServletPath();
                 pathInfo=request.getPathInfo();
             }
         }
         else
         {
             servletPath = _pathInfoOnly?"/":request.getServletPath();
             pathInfo = request.getPathInfo();
 
             // Is this a Range request?
             reqRanges = request.getHeaders(HttpHeader.RANGE.asString());
             if (!hasDefinedRange(reqRanges))
                 reqRanges = null;
         }
 
         String pathInContext=URIUtil.addPaths(servletPath,pathInfo);
         boolean endsWithSlash=(pathInfo==null?request.getServletPath():pathInfo).endsWith(URIUtil.SLASH);
         boolean gzippable=_gzip && !endsWithSlash && !included && reqRanges==null;
         
         HttpContent content=null;
         boolean release_content=true;
         try
         {
             // Find the content
             content=_contentFactory.getContent(pathInContext,response.getBufferSize());
             if (LOG.isDebugEnabled())
                 LOG.info("content={}",content);
             
             // Not found?
             if (content==null || !content.getResource().exists())
             {
                 if (included)
                     throw new FileNotFoundException("!" + pathInContext);
                 response.sendError(HttpServletResponse.SC_NOT_FOUND);
                 return;
             }
             
             // Directory?
             if (content.getResource().isDirectory())
             {
                 sendWelcome(content,pathInContext,endsWithSlash,included,request,response);
                 return;
             }
             
             // Strip slash?
             if (endsWithSlash && pathInContext.length()>1)
             {
                 String q=request.getQueryString();
                 pathInContext=pathInContext.substring(0,pathInContext.length()-1);
                 if (q!=null&&q.length()!=0)
                     pathInContext+="?"+q;
                 response.sendRedirect(response.encodeRedirectURL(URIUtil.addPaths(_servletContext.getContextPath(),pathInContext)));
                 return;
             }
             
             // Conditional response?
             if (!included && !passConditionalHeaders(request,response,content))
                 return;
                 
             // Gzip?
             HttpContent gzip_content = gzippable?content.getGzipContent():null;
             if (gzip_content!=null)
             {
                 // Tell caches that response may vary by accept-encoding
                 response.addHeader(HttpHeader.VARY.asString(),HttpHeader.ACCEPT_ENCODING.asString());
                 
                 // Does the client accept gzip?
                 String accept=request.getHeader(HttpHeader.ACCEPT_ENCODING.asString());
                 if (accept!=null && accept.indexOf("gzip")>=0)
                 {
                     if (LOG.isDebugEnabled())
                         LOG.debug("gzip={}",gzip_content);
                     content=gzip_content;
                 }
             }
 
             // TODO this should be done by HttpContent#getContentEncoding
             if (isGzippedContent(pathInContext))
                 response.setHeader(HttpHeader.CONTENT_ENCODING.asString(),"gzip");
                 
             // Send the data
             release_content=sendData(request,response,included,content,reqRanges);
             
         }
         catch(IllegalArgumentException e)
         {
             LOG.warn(Log.EXCEPTION,e);
             if(!response.isCommitted())
                 response.sendError(500, e.getMessage());
         }
         finally
         {
             if (release_content)
             {
                 if (content!=null)
                     content.release();
             }
         }
 
     }
 
     protected void sendWelcome(HttpContent content, String pathInContext, boolean endsWithSlash, boolean included, HttpServletRequest request, HttpServletResponse response)
         throws ServletException, IOException
     {                
         // Redirect to directory
         if (!endsWithSlash || (pathInContext.length()==1 && request.getAttribute("org.eclipse.jetty.server.nullPathInfo")!=null))
         {
             StringBuffer buf=request.getRequestURL();
             synchronized(buf)
             {
                 int param=buf.lastIndexOf(";");
                 if (param<0)
                     buf.append('/');
                 else
                     buf.insert(param,'/');
                 String q=request.getQueryString();
                 if (q!=null&&q.length()!=0)
                 {
                     buf.append('?');
                     buf.append(q);
                 }
                 response.setContentLength(0);
                 response.sendRedirect(response.encodeRedirectURL(buf.toString()));
             }
             return;
         }
         
         // look for a welcome file
         String welcome=getWelcomeFile(pathInContext);
         if (welcome!=null)
         {
             if (LOG.isDebugEnabled())
                 LOG.debug("welcome={}",welcome);
             if (_redirectWelcome)
             {
                 // Redirect to the index
                 response.setContentLength(0);
                 String q=request.getQueryString();
                 if (q!=null&&q.length()!=0)
                     response.sendRedirect(response.encodeRedirectURL(URIUtil.addPaths( _servletContext.getContextPath(),welcome)+"?"+q));
                 else
                     response.sendRedirect(response.encodeRedirectURL(URIUtil.addPaths( _servletContext.getContextPath(),welcome)));
             }
             else
             {
                 // Forward to the index
                 RequestDispatcher dispatcher=request.getRequestDispatcher(welcome);
                 if (dispatcher!=null)
                 {
                     if (included)
                         dispatcher.include(request,response);
                     else
                     {
                         request.setAttribute("org.eclipse.jetty.server.welcome",welcome);
                         dispatcher.forward(request,response);
                     }
                 }
             }
             return;
         }
          
         if (included || passConditionalHeaders(request,response, content))
             sendDirectory(request,response,content.getResource(),pathInContext);
     }
 
     /* ------------------------------------------------------------ */
     protected boolean isGzippedContent(String path)
     {
         if (path == null) return false;
       
         for (String suffix:_gzipEquivalentFileExtensions)
             if (path.endsWith(suffix))
                 return true;
         return false;
     }
 
     /* ------------------------------------------------------------ */
     private boolean hasDefinedRange(Enumeration<String> reqRanges)
     {
         return (reqRanges!=null && reqRanges.hasMoreElements());
     }
 
     /* ------------------------------------------------------------ */
     @Override
     protected void doPost(HttpServletRequest request, HttpServletResponse response)
     throws ServletException, IOException
     {
         doGet(request,response);
     }
 
     /* ------------------------------------------------------------ */
     /* (non-Javadoc)
      * @see javax.servlet.http.HttpServlet#doTrace(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse)
      */
     @Override
     protected void doTrace(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException
     {
         resp.sendError(HttpServletResponse.SC_METHOD_NOT_ALLOWED);
     }
 
     /* ------------------------------------------------------------ */
     @Override
     protected void doOptions(HttpServletRequest req, HttpServletResponse resp)
     throws ServletException, IOException
     {
         resp.setHeader("Allow", "GET,HEAD,POST,OPTIONS");
     }
 
     /* ------------------------------------------------------------ */
     /**
      * Finds a matching welcome file for the supplied {@link Resource}. This will be the first entry in the list of
      * configured {@link #_welcomes welcome files} that existing within the directory referenced by the <code>Resource</code>.
      * If the resource is not a directory, or no matching file is found, then it may look for a valid servlet mapping.
      * If there is none, then <code>null</code> is returned.
      * The list of welcome files is read from the {@link ContextHandler} for this servlet, or
      * <code>"index.jsp" , "index.html"</code> if that is <code>null</code>.
      * @param resource
      * @return The path of the matching welcome file in context or null.
      * @throws IOException
      * @throws MalformedURLException
      */
     private String getWelcomeFile(String pathInContext) throws MalformedURLException, IOException
     {
         if (_welcomes==null)
             return null;
 
         String welcome_servlet=null;
         for (int i=0;i<_welcomes.length;i++)
         {
             String welcome_in_context=URIUtil.addPaths(pathInContext,_welcomes[i]);
             Resource welcome=getResource(welcome_in_context);
             if (welcome!=null && welcome.exists())
                 return _welcomes[i];
 
             if ((_welcomeServlets || _welcomeExactServlets) && welcome_servlet==null)
             {
                 MappedEntry<?> entry=_servletHandler.getHolderEntry(welcome_in_context);
                 if (entry!=null && entry.getValue()!=_defaultHolder &&
                         (_welcomeServlets || (_welcomeExactServlets && entry.getKey().equals(welcome_in_context))))
                     welcome_servlet=welcome_in_context;
 
             }
         }
         return welcome_servlet;
     }
 
     /* ------------------------------------------------------------ */
     /* Check modification date headers.
      */
     protected boolean passConditionalHeaders(HttpServletRequest request,HttpServletResponse response, HttpContent content)
     throws IOException
     {
         try
         {
             String ifm=null;
             String ifnm=null;
             String ifms=null;
             long ifums=-1;
             
             if (request instanceof Request)
             {
                 // Find multiple fields by iteration as an optimization 
                 HttpFields fields = ((Request)request).getHttpFields();
                 for (int i=fields.size();i-->0;)
                 {
                     HttpField field=fields.getField(i);
                     if (field.getHeader() != null)
                     {
                         switch (field.getHeader())
                         {
                             case IF_MATCH:
                                 ifm=field.getValue();
                                 break;
                             case IF_NONE_MATCH:
                                 ifnm=field.getValue();
                                 break;
                             case IF_MODIFIED_SINCE:
                                 ifms=field.getValue();
                                 break;
                             case IF_UNMODIFIED_SINCE:
                                 ifums=DateParser.parseDate(field.getValue());
                                 break;
                             default:
                         }
                     }
                 }
             }
             else
             {
                 ifm=request.getHeader(HttpHeader.IF_MATCH.asString());
                 ifnm=request.getHeader(HttpHeader.IF_NONE_MATCH.asString());
                 ifms=request.getHeader(HttpHeader.IF_MODIFIED_SINCE.asString());
                 ifums=request.getDateHeader(HttpHeader.IF_UNMODIFIED_SINCE.asString());
             }
             
             if (!HttpMethod.HEAD.is(request.getMethod()))
             {
                 if (_etags)
                 {
                     String etag=content.getETagValue();
                     if (ifm!=null)
                     {
                         boolean match=false;
                         if (etag!=null)
                         {
                             QuotedStringTokenizer quoted = new QuotedStringTokenizer(ifm,", ",false,true);
                             while (!match && quoted.hasMoreTokens())
                             {
                                 String tag = quoted.nextToken();
                                 if (etag.equals(tag) || tag.endsWith(ETAG_GZIP_QUOTE) && etag.equals(removeGzipFromETag(tag)))
                                     match=true;
                             }
                         }
 
                         if (!match)
                         {
                             response.setStatus(HttpServletResponse.SC_PRECONDITION_FAILED);
                             return false;
                         }
                     }
                     
                     if (ifnm!=null && etag!=null)
                     {
                         // Handle special case of exact match OR gzip exact match
                         if (etag.equals(ifnm) || ifnm.endsWith(ETAG_GZIP_QUOTE) && ifnm.indexOf(',')<0 && etag.equals(removeGzipFromETag(etag)))
                         {
                             response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                             response.setHeader(HttpHeader.ETAG.asString(),ifnm);
                             return false;
                         }
                         
                         // Handle list of tags
                         QuotedStringTokenizer quoted = new QuotedStringTokenizer(ifnm,", ",false,true);
                         while (quoted.hasMoreTokens())
                         {
                             String tag = quoted.nextToken();
                             if (etag.equals(tag) || tag.endsWith(ETAG_GZIP_QUOTE) && etag.equals(removeGzipFromETag(tag))) 
                             {
                                 response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                                 response.setHeader(HttpHeader.ETAG.asString(),tag);
                                 return false;
                             }
                         }
                         
                         // If etag requires content to be served, then do not check if-modified-since
                         return true;
                     }
                 }
                 
                 // Handle if modified since
                 if (ifms!=null)
                 {
                     //Get jetty's Response impl
                     String mdlm=content.getLastModifiedValue();
                     if (mdlm!=null && ifms.equals(mdlm))
                     {
                         response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                         if (_etags)
                             response.setHeader(HttpHeader.ETAG.asString(),content.getETagValue());
                         response.flushBuffer();
                         return false;
                     }
 
                     long ifmsl=request.getDateHeader(HttpHeader.IF_MODIFIED_SINCE.asString());
                     if (ifmsl!=-1 && content.getResource().lastModified()/1000 <= ifmsl/1000)
                     { 
                         response.setStatus(HttpServletResponse.SC_NOT_MODIFIED);
                         if (_etags)
                             response.setHeader(HttpHeader.ETAG.asString(),content.getETagValue());
                         response.flushBuffer();
                         return false;
                     }
                 }
 
                 // Parse the if[un]modified dates and compare to resource
                 if (ifums!=-1 && content.getResource().lastModified()/1000 > ifums/1000)
                 {
                     response.sendError(HttpServletResponse.SC_PRECONDITION_FAILED);
                     return false;
                 }
 
             }
         }
         catch(IllegalArgumentException iae)
         {
             if(!response.isCommitted())
                 response.sendError(400, iae.getMessage());
             throw iae;
         }
         return true;
     }
 
 
     /* ------------------------------------------------------------------- */
     protected void sendDirectory(HttpServletRequest request,
             HttpServletResponse response,
             Resource resource,
             String pathInContext)
     throws IOException
     {
         if (!_dirAllowed)
         {
             response.sendError(HttpServletResponse.SC_FORBIDDEN);
             return;
         }
 
         byte[] data=null;
         String base = URIUtil.addPaths(request.getRequestURI(),URIUtil.SLASH);
 
         //If the DefaultServlet has a resource base set, use it
         if (_resourceBase != null)
         {
             // handle ResourceCollection
             if (_resourceBase instanceof ResourceCollection)
                 resource=_resourceBase.addPath(pathInContext);
         }
         //Otherwise, try using the resource base of its enclosing context handler
         else if (_contextHandler.getBaseResource() instanceof ResourceCollection)
             resource=_contextHandler.getBaseResource().addPath(pathInContext);
 
         String dir = resource.getListHTML(base,pathInContext.length()>1);
         if (dir==null)
         {
             response.sendError(HttpServletResponse.SC_FORBIDDEN,
             "No directory");
             return;
         }
 
         data=dir.getBytes("utf-8");
         response.setContentType("text/html;charset=utf-8");
         response.setContentLength(data.length);
         response.getOutputStream().write(data);
     }
 
     /* ------------------------------------------------------------ */
     protected boolean sendData(HttpServletRequest request,
             HttpServletResponse response,
             boolean include,
             final HttpContent content,
             Enumeration<String> reqRanges)
     throws IOException
     {
         final long content_length = content.getContentLengthValue();
         
         // Get the output stream (or writer)
         OutputStream out =null;
         boolean written;
         try
         {
             out = response.getOutputStream();
 
             // has something already written to the response?
             written = out instanceof HttpOutput
                 ? ((HttpOutput)out).isWritten()
                 : true;
         }
         catch(IllegalStateException e)
         {
             out = new WriterOutputStream(response.getWriter());
             written=true; // there may be data in writer buffer, so assume written
         }
         
         if (LOG.isDebugEnabled())
             LOG.debug(String.format("sendData content=%s out=%s async=%b",content,out,request.isAsyncSupported()));
 
         if ( reqRanges == null || !reqRanges.hasMoreElements() || content_length<0)
         {
             //  if there were no ranges, send entire entity
             if (include)
             {
                 // write without headers
                 content.getResource().writeTo(out,0,content_length);
             }
             // else if we can't do a bypass write because of wrapping
             else if (written || !(out instanceof HttpOutput))
             {
                 // write normally
                 putHeaders(response,content,written?-1:0);
                 ByteBuffer buffer = content.getIndirectBuffer();
                 if (buffer!=null)
                     BufferUtil.writeTo(buffer,out);
                 else
                     content.getResource().writeTo(out,0,content_length);
             }
             // else do a bypass write
             else
             {
                 // write the headers
                 putHeaders(response,content,0);
 
                 // write the content asynchronously if supported
                 if (request.isAsyncSupported())
                 {
                     final AsyncContext context = request.startAsync();
                     context.setTimeout(0);
 
                     ((HttpOutput)out).sendContent(content,new Callback()
                     {
                         @Override
                         public void succeeded()
                         {   
                             context.complete();
                             content.release();
                         }
 
                         @Override
                         public void failed(Throwable x)
                         {
                             if (x instanceof IOException)
                                 LOG.debug(x);
                             else
                                 LOG.warn(x);
                             context.complete();
                             content.release();
                         }
                         
                         @Override
                         public String toString() 
                         {
                             return String.format("DefaultServlet@%x$CB", DefaultServlet.this.hashCode());
                         }
                     });
                     return false;
                 }
                 // otherwise write content blocking
                 ((HttpOutput)out).sendContent(content);
             }
         }
         else
         {
             // Parse the satisfiable ranges
             List<InclusiveByteRange> ranges =InclusiveByteRange.satisfiableRanges(reqRanges,content_length);
 
             //  if there are no satisfiable ranges, send 416 response
             if (ranges==null || ranges.size()==0)
             {
                 putHeaders(response,content,0);
                 response.setStatus(HttpServletResponse.SC_REQUESTED_RANGE_NOT_SATISFIABLE);
                 response.setHeader(HttpHeader.CONTENT_RANGE.asString(),
                         InclusiveByteRange.to416HeaderRangeString(content_length));
                 content.getResource().writeTo(out,0,content_length);
                 return true;
             }
 
             //  if there is only a single valid range (must be satisfiable
             //  since were here now), send that range with a 216 response
             if ( ranges.size()== 1)
             {
                 InclusiveByteRange singleSatisfiableRange = ranges.get(0);
                 long singleLength = singleSatisfiableRange.getSize(content_length);
                 putHeaders(response,content,singleLength);
                 response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
                 if (!response.containsHeader(HttpHeader.DATE.asString()))
                     response.addDateHeader(HttpHeader.DATE.asString(),System.currentTimeMillis());
                 response.setHeader(HttpHeader.CONTENT_RANGE.asString(),
                         singleSatisfiableRange.toHeaderRangeString(content_length));
                 content.getResource().writeTo(out,singleSatisfiableRange.getFirst(content_length),singleLength);
                 return true;
             }
 
             //  multiple non-overlapping valid ranges cause a multipart
             //  216 response which does not require an overall
             //  content-length header
             //
             putHeaders(response,content,-1);
             String mimetype=(content==null?null:content.getContentTypeValue());
             if (mimetype==null)
                 LOG.warn("Unknown mimetype for "+request.getRequestURI());
             MultiPartOutputStream multi = new MultiPartOutputStream(out);
             response.setStatus(HttpServletResponse.SC_PARTIAL_CONTENT);
             if (!response.containsHeader(HttpHeader.DATE.asString()))
                 response.addDateHeader(HttpHeader.DATE.asString(),System.currentTimeMillis());
 
             // If the request has a "Request-Range" header then we need to
             // send an old style multipart/x-byteranges Content-Type. This
             // keeps Netscape and acrobat happy. This is what Apache does.
             String ctp;
             if (request.getHeader(HttpHeader.REQUEST_RANGE.asString())!=null)
                 ctp = "multipart/x-byteranges; boundary=";
             else
                 ctp = "multipart/byteranges; boundary=";
             response.setContentType(ctp+multi.getBoundary());
 
             InputStream in=content.getResource().getInputStream();
             long pos=0;
 
             // calculate the content-length
             int length=0;
             String[] header = new String[ranges.size()];
             for (int i=0;i<ranges.size();i++)
             {
                 InclusiveByteRange ibr = ranges.get(i);
                 header[i]=ibr.toHeaderRangeString(content_length);
                 length+=
                     ((i>0)?2:0)+
                     2+multi.getBoundary().length()+2+
                     (mimetype==null?0:HttpHeader.CONTENT_TYPE.asString().length()+2+mimetype.length())+2+
                     HttpHeader.CONTENT_RANGE.asString().length()+2+header[i].length()+2+
                     2+
                     (ibr.getLast(content_length)-ibr.getFirst(content_length))+1;
             }
             length+=2+2+multi.getBoundary().length()+2+2;
             response.setContentLength(length);
 
             for (int i=0;i<ranges.size();i++)
             {
                 InclusiveByteRange ibr =  ranges.get(i);
                 multi.startPart(mimetype,new String[]{HttpHeader.CONTENT_RANGE+": "+header[i]});
 
                 long start=ibr.getFirst(content_length);
                 long size=ibr.getSize(content_length);
                 if (in!=null)
                 {
                     // Handle non cached resource
                     if (start<pos)
                     {
                         in.close();
                         in=content.getResource().getInputStream();
                         pos=0;
                     }
                     if (pos<start)
                     {
                         in.skip(start-pos);
                         pos=start;
                     }
                     
                     IO.copy(in,multi,size);
                     pos+=size;
                 }
                 else
                     // Handle cached resource
                     content.getResource().writeTo(multi,start,size);
             }
             if (in!=null)
                 in.close();
             multi.close();
         }
         return true;
     }
 
     /* ------------------------------------------------------------ */
     protected void putHeaders(HttpServletResponse response,HttpContent content, long contentLength)
     {
         if (response instanceof Response)
         {
             Response r = (Response)response;
             r.putHeaders(content,contentLength,_etags);
             HttpFields f = r.getHttpFields();
             if (_acceptRanges)
                 f.put(ACCEPT_RANGES);
 
             if (_cacheControl!=null)
                 f.put(_cacheControl);
         }
         else
         {
             Response.putHeaders(response,content,contentLength,_etags);
             if (_acceptRanges)
                 response.setHeader(ACCEPT_RANGES.getName(),ACCEPT_RANGES.getValue());
 
             if (_cacheControl!=null)
                 response.setHeader(_cacheControl.getName(),_cacheControl.getValue());
         }
     }
 
     /* ------------------------------------------------------------ */
     /*
      * @see javax.servlet.Servlet#destroy()
      */
     @Override
     public void destroy()
     {
         if (_cache!=null)
             _cache.flushCache();
         super.destroy();
     }
 
 }