Enforces limit of query tree size if configured

2 files changed, 36 insertions, 2 deletions

diff --git a/container-search/src/main/java/com/yahoo/prelude/query/QueryCanonicalizer.java b/container-search/src/main/java/com/yahoo/prelude/query/QueryCanonicalizer.java
index 1f30833b3db..14e316c1877 100644
--- a/container-search/src/main/java/com/yahoo/prelude/query/QueryCanonicalizer.java
+++ b/container-search/src/main/java/com/yahoo/prelude/query/QueryCanonicalizer.java
@@ -1,6 +1,7 @@
 // Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 package com.yahoo.prelude.query;
 
+import com.yahoo.processing.request.CompoundName;
 import com.yahoo.search.Query;
 import com.yahoo.search.query.QueryTree;
 
@@ -19,6 +20,8 @@ public class QueryCanonicalizer {
     /** The name of the operation performed by this, for use in search chain ordering */
     public static final String queryCanonicalization = "queryCanonicalization";
 
+    private static final CompoundName MAX_QUERY_ITEMS = new CompoundName("maxQueryItems");
+
     /**
      * Validates this query and carries out possible operations on this query
      * which simplifies it without changing its semantics.
@@ -26,7 +29,17 @@ public class QueryCanonicalizer {
      * @return null if the query is valid, an error message if it is invalid
      */
     public static String canonicalize(Query query) {
-        return canonicalize(query.getModel().getQueryTree());
+        Integer maxQueryItems = query.properties().getInteger(MAX_QUERY_ITEMS, Integer.MAX_VALUE);
+        return canonicalize(query.getModel().getQueryTree(), maxQueryItems);
+    }
+
+    /**
+     * Canonicalizes this query, allowing any query tree size
+     *
+     * @return null if the query is valid, an error message if it is invalid
+     */
+    public static String canonicalize(QueryTree queryTree) {
+        return canonicalize(queryTree, Integer.MAX_VALUE);
     }
 
     /**
@@ -34,10 +47,11 @@ public class QueryCanonicalizer {
      * 
      * @return null if the query is valid, an error message if it is invalid
      */
-    public static String canonicalize(QueryTree query) {
+    private static String canonicalize(QueryTree query, Integer maxQueryItems) {
         ListIterator<Item> rootItemIterator = query.getItemIterator();
         CanonicalizationResult result = recursivelyCanonicalize(rootItemIterator.next(), rootItemIterator);
         if (query.isEmpty() && ! result.isError()) result = CanonicalizationResult.error("No query");
+        if (query.getTreeSize() > maxQueryItems) result = CanonicalizationResult.error("Query tree exceeds allowed item count");
         return result.error().orElse(null); // preserve old API, unfortunately
     }
 
diff --git a/container-search/src/main/java/com/yahoo/search/query/QueryTree.java b/container-search/src/main/java/com/yahoo/search/query/QueryTree.java
index 2fb16ef503f..dab481dc842 100644
--- a/container-search/src/main/java/com/yahoo/search/query/QueryTree.java
+++ b/container-search/src/main/java/com/yahoo/search/query/QueryTree.java
@@ -7,6 +7,7 @@ import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
+import java.util.ListIterator;
 
 /**
  * The root node of a query tree. This is always present above the actual semantic root to ease query manipulation,
@@ -179,4 +180,23 @@ public class QueryTree extends CompositeItem {
         }
     }
 
+    /**
+     * @return The total number of items in this query tree
+     */
+    public int getTreeSize() {
+        if (isEmpty()) return 0;
+        return(countItemsRecursively(getItemIterator().next()));
+    }
+
+    private int countItemsRecursively(Item item) {
+        int children = 0;
+        if (item instanceof CompositeItem) {
+            CompositeItem composite = (CompositeItem)item;
+            for (ListIterator<Item> i = composite.getItemIterator(); i.hasNext(); ) {
+                children += countItemsRecursively(i.next());
+            }
+        }
+        return children + 1;
+    }
+
 }