Added getAcceptableTokens to Check.

Prevent registration for tokens the Check is not
designed for

src/checkstyle/com/puppycrawl/tools/checkstyle/TreeWalker.java

@@ -30,6 +30,7 @@ import java.util.HashSet;
 import java.util.Iterator;
 import java.util.Map;
 import java.util.Set;
+import java.util.Arrays;
 
 /**
  * Responsible for walking an abstract syntax tree and notifying interested
@@ -73,9 +74,16 @@ class TreeWalker
         aCheck.setMessages(mMessages);
         aCheck.setTabWidth(mTabWidth);
         if (!aConfig.getTokens().isEmpty()) {
+            int acceptableTokens[] = aCheck.getAcceptableTokens();
+            Arrays.sort(acceptableTokens);
             final Iterator it = aConfig.getTokens().iterator();
             while (it.hasNext()) {
-                registerCheck((String) it.next(), aCheck);
+                String token = (String) it.next();
+                int tokenId = TokenTypes.getTokenId(token);
+                if (Arrays.binarySearch(acceptableTokens, tokenId) >= 0) {
+                    registerCheck(token, aCheck);
+                }
+                // TODO: else error message?
             }
         }
         else {

src/checkstyle/com/puppycrawl/tools/checkstyle/api/Check.java

@@ -19,6 +19,7 @@
 package com.puppycrawl.tools.checkstyle.api;
 
 import java.util.Map;
+import java.util.Arrays;
 
 /**
  * The base class for checks.
@@ -55,6 +56,27 @@ public abstract class Check
      */
     public abstract int[] getDefaultTokens();
 
+    /**
+     * The token set this check is designed for. Used to protect Checks
+     * against malicious users who specify a meaningless token set in the
+     * config file.
+     * The default implementations returns the check's default tokens.
+     * @return the token set this check is designed for.
+     */
+    public int[] getAcceptableTokens()
+    {
+        int[] defaultTokens = getDefaultTokens();
+        int[] copy = new int[defaultTokens.length];
+        System.arraycopy(defaultTokens, 0, copy, 0, defaultTokens.length);
+        return copy;
+    }
+
+
+    // TODO: oburn on checkstyle-dev: another method should be added
+    // to specify the tokens that a check must have. For some checks to
+    // work, they must be registered for some tokens.
+
+
     /**
      * Return the global context object for check. This context is valid for
      * the lifetime of the check.

src/checkstyle/com/puppycrawl/tools/checkstyle/api/TokenTypes.java

@@ -388,4 +388,18 @@ public class TokenTypes
         }
         return name;
     }
+
+    /**
+     * Returns the ID of a token for a given name.
+     * @param aName the name of the token ID to get
+     * @return a token ID
+     */
+    public static int getTokenId(String aName)
+    {
+        final Integer id = (Integer) TOKEN_NAME_TO_VALUE.get(aName);
+        if (id == null) {
+            throw new IllegalArgumentException("given name " + aName);
+        }
+        return id.intValue();
+    }
 }