Limit the value in prefix query (#108537)

Reuse the setting index.max_regex_length for the max length in a prefix query.

Closes #108486

docs/changelog/108537.yaml

@@ -0,0 +1,6 @@
+pr: 108537
+summary: Limit the value in prefix query
+area: Search
+type: enhancement
+issues:
+ - 108486

docs/reference/index-modules.asciidoc

@@ -304,7 +304,7 @@ are ignored for this index.
 [[index-max-regex-length]]
  `index.max_regex_length`::
 
-    The maximum length of regex that can be used in Regexp Query.
+    The maximum length of value that can be used in `regexp` or `prefix` query.
     Defaults to `1000`.
 
 [[index-query-default-field]]

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search/30_limits.yml

@@ -161,3 +161,31 @@ setup:
                      ]))|\\[([^\\[\\]\\r\\\\]|\\\\.)*\\](?:(?:\\r\\n)?[\\t])*))*\\>(?:(?:\\r\\n)?[ \\t])*)(?:,\\s*( |
                      \".\\[\\]]))|\"(?:[^\\\"\\r\\\\]|\\\\.|(?:(?:\\r\\n)?[\\t]))*\"(?:(?:\\r\\n)?[ \\t])*)(?:\\.(?:( |
                      \\[\"()<>@,;:\\\\\".\\[\\]]))|\"(?:[^\\\"\\r\\\\]|\\\\.|(?:(?:\\r\\n)?[\\t]))*\"(?:(?:\\r\\n)?[\\t/"
+
+---
+"Prefix length limit":
+
+  - requires:
+      cluster_features: "gte_v8.15.0"
+      reason: "Limit for value in prefix query was introduced in 8.15"
+
+  - do:
+      catch: /The length of prefix \[1110\] used in the Prefix Query request has exceeded the allowed maximum of \[1000\]\. This maximum can be set by changing the \[index.max_regex_length\] index level setting\./
+      search:
+        rest_total_hits_as_int: true
+        index: test_1
+        body:
+          query:
+            prefix:
+              foo: "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
+                    aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa"

server/src/internalClusterTest/java/org/elasticsearch/search/simple/SimpleSearchIT.java

@@ -490,6 +490,46 @@ public class SimpleSearchIT extends ESIntegTestCase {
         );
     }
 
+    public void testTooLongPrefixInPrefixQuery() throws Exception {
+        createIndex("idx");
+
+        // Ensure the field `num` exists in the mapping
+        client().admin()
+            .indices()
+            .preparePutMapping("idx")
+            .setSource("{\"properties\":{\"num\":{\"type\":\"keyword\"}}}", XContentType.JSON)
+            .get();
+
+        // Index a simple document to ensure the field `num` is in the index
+        indexRandom(true, prepareIndex("idx").setSource("{\"num\":\"test\"}", XContentType.JSON));
+
+        int defaultMaxRegexLength = IndexSettings.MAX_REGEX_LENGTH_SETTING.get(Settings.EMPTY);
+        StringBuilder prefix = new StringBuilder(defaultMaxRegexLength);
+
+        while (prefix.length() <= defaultMaxRegexLength) {
+            prefix.append("a");
+        }
+
+        SearchPhaseExecutionException e = expectThrows(
+            SearchPhaseExecutionException.class,
+            () -> client().prepareSearch("idx").setQuery(QueryBuilders.prefixQuery("num", prefix.toString())).get()
+        );
+        assertThat(
+            e.getRootCause().getMessage(),
+            containsString(
+                "The length of prefix ["
+                    + prefix.length()
+                    + "] used in the Prefix Query request has exceeded "
+                    + "the allowed maximum of ["
+                    + defaultMaxRegexLength
+                    + "]. "
+                    + "This maximum can be set by changing the ["
+                    + IndexSettings.MAX_REGEX_LENGTH_SETTING.getKey()
+                    + "] index level setting."
+            )
+        );
+    }
+
     public void testStrictlyCountRequest() throws Exception {
         createIndex("test_count_1");
         indexRandom(

server/src/main/java/org/elasticsearch/index/query/PrefixQueryBuilder.java

@@ -19,6 +19,7 @@ import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.xcontent.LoggingDeprecationHandler;
+import org.elasticsearch.index.IndexSettings;
 import org.elasticsearch.index.mapper.ConstantFieldType;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.support.QueryParsers;
@@ -209,6 +210,20 @@ public class PrefixQueryBuilder extends AbstractQueryBuilder<PrefixQueryBuilder>
 
     @Override
     protected Query doToQuery(SearchExecutionContext context) throws IOException {
+        final int maxAllowedRegexLength = context.getIndexSettings().getMaxRegexLength();
+        if (value.length() > maxAllowedRegexLength) {
+            throw new IllegalArgumentException(
+                "The length of prefix ["
+                    + value.length()
+                    + "] used in the Prefix Query request has exceeded "
+                    + "the allowed maximum of ["
+                    + maxAllowedRegexLength
+                    + "]. "
+                    + "This maximum can be set by changing the ["
+                    + IndexSettings.MAX_REGEX_LENGTH_SETTING.getKey()
+                    + "] index level setting."
+            );
+        }
         MultiTermQuery.RewriteMethod method = QueryParsers.parseRewriteMethod(rewrite, null, LoggingDeprecationHandler.INSTANCE);
 
         MappedFieldType fieldType = context.getFieldType(fieldName);