java/src/main/com/google/apphosting/utils/config/DosXmlReader.java

   1 // Copyright 2010 Google Inc. All Rights Reserved.
   2 package com.google.apphosting.utils.config;
   3
   4 import org.mortbay.xml.XmlParser.Node;
   5
   6 import java.io.InputStream;
   7 import java.util.Stack;
   8
   9 /**
  10  * Creates an {@link DosXml} instance from
  11  * <appdir>WEB-INF/dos.xml.  If you want to read the configuration
  12  * from a different file, subclass and override {@link #getFilename()}.  If you
  13  * want to read the configuration from something that isn't a file, subclass
  14  * and override {@link #getInputStream()}.
  15  *
  16  */
  17 public class DosXmlReader extends AbstractConfigXmlReader<DosXml> {
  18
  19   private static final String FILENAME = "WEB-INF/dos.xml";
  20
  21   private static final String BLACKLISTENTRIES_TAG = "blacklistentries";
  22   private static final String BLACKLIST_TAG = "blacklist";
  23   private static final String DESCRIPTION_TAG = "description";
  24   private static final String SUBNET_TAG = "subnet";
  25
  26   /**
  27    * Constructs the reader for {@code dos.xml} in a given application directory.
  28    * @param appDir the application directory
  29    */
  30   public DosXmlReader(String appDir) {
  31     super(appDir, false);
  32   }
  33
  34   /**
  35    * Parses the config file.
  36    * @return A {@link DosXml} object representing the parsed configuration.
  37    */
  38   public DosXml readDosXml() {
  39     return readConfigXml();
  40   }
  41
  42   @Override
  43   protected DosXml processXml(InputStream is) {
  44     final DosXml dosXml = new DosXml();
  45     parse(new ParserCallback() {
  46       boolean first = true;
  47       DosXml.BlacklistEntry blacklistEntry;
  48
  49       @Override
  50       public void newNode(Node node, Stack<Node> ancestors) {
  51         switch (ancestors.size()) {
  52           case 0:
  53             if (!BLACKLISTENTRIES_TAG.equalsIgnoreCase(node.getTag())) {
  54               throw new AppEngineConfigException(getFilename() + " does not contain <"
  55                   + BLACKLISTENTRIES_TAG + ">");
  56             }
  57             if (!first) {
  58               throw new AppEngineConfigException(getFilename() + " contains multiple <"
  59                   + BLACKLISTENTRIES_TAG + ">");
  60             }
  61             first = false;
  62             break;
  63
  64           case 1:
  65             if (BLACKLIST_TAG.equalsIgnoreCase(node.getTag())) {
  66               blacklistEntry = dosXml.addNewBlacklistEntry();
  67             } else {
  68               throw new AppEngineConfigException(getFilename() + " contains <"
  69                   + node.getTag() + "> instead of <" + BLACKLIST_TAG + "/>");
  70             }
  71             break;
  72
  73           case 2:
  74             assert(blacklistEntry != null);
  75             if (DESCRIPTION_TAG.equalsIgnoreCase(node.getTag())) {
  76               if (node.size() == 1 && node.get(0) instanceof String) {
  77                 blacklistEntry.setDescription((String) node.get(0));
  78               } else {
  79                 throw new AppEngineConfigException(getFilename() + " has bad contents in <"
  80                     + DESCRIPTION_TAG + ">");
  81               }
  82             } else if (SUBNET_TAG.equalsIgnoreCase(node.getTag())) {
  83                 if (node.size() == 1 && node.get(0) instanceof String) {
  84                   blacklistEntry.setSubnet((String) node.get(0));
  85                 } else {
  86                   throw new AppEngineConfigException(getFilename() + " has bad contents in <"
  87                       + SUBNET_TAG + ">");
  88                 }
  89             } else {
  90               throw new AppEngineConfigException(getFilename() + " contains unknown <"
  91                   + node.getTag() + "> inside <" + BLACKLIST_TAG + "/>");
  92             }
  93             break;
  94
  95           default:
  96             throw new AppEngineConfigException(getFilename()
  97                 + " has a syntax error; node <"
  98                 + node.getTag() + "> is too deeply nested to be valid.");
  99         }
 100       }
 101     }, is);
 102     dosXml.validateLastEntry();
 103     return dosXml;
 104   }
 105
 106   @Override
 107   protected String getRelativeFilename() {
 108     return FILENAME;
 109   }
 110 }