Json parsing exceptions should not cause 500 errors (elastic#111548)

Currently we wrap JsonEOFException from advancing the json parser into our own
XContentEOFException, but this has the drawback that is results in 500 errors on
the client side. Instead this should be 400 errors.
This changes XContentEOFException to extend XContentParseException so we report
a 400 error instead.

Closes elastic#111542

docs/changelog/111548.yaml

@@ -0,0 +1,6 @@
+pr: 111548
+summary: Json parsing exceptions should not cause 500 errors
+area: Infra/Core
+type: bug
+issues:
+ - 111542

libs/x-content/impl/src/main/java/org/elasticsearch/xcontent/provider/json/JsonXContentParser.java

@@ -57,7 +57,8 @@ public Token nextToken() throws IOException {
         try {
             return convertToken(parser.nextToken());
         } catch (JsonEOFException e) {
-            throw new XContentEOFException(e);
+            JsonLocation location = e.getLocation();
+            throw new XContentEOFException(new XContentLocation(location.getLineNr(), location.getColumnNr()), "Unexpected end of file", e);
         } catch (JsonParseException e) {
             throw newXContentParseException(e);
         }

libs/x-content/src/main/java/org/elasticsearch/xcontent/XContentEOFException.java

@@ -8,11 +8,9 @@
 
 package org.elasticsearch.xcontent;
 
-import java.io.IOException;
+public class XContentEOFException extends XContentParseException {
 
-public class XContentEOFException extends IOException {
-
-    public XContentEOFException(IOException cause) {
-        super(cause);
+    public XContentEOFException(XContentLocation location, String message, Exception cause) {
+        super(location, message, cause);
     }
 }

modules/lang-mustache/src/yamlRestTest/resources/rest-api-spec/test/lang_mustache/50_multi_search_template.yml

@@ -114,14 +114,14 @@ setup:
 
   - match:  { responses.0.hits.total:     2  }
   - match:  { responses.1.error.root_cause.0.type: x_content_e_o_f_exception }
-  - match:  { responses.1.error.root_cause.0.reason: "/Unexpected.end.of.input/" }
+  - match:  { responses.1.error.root_cause.0.reason: "/\\[1:22\\].Unexpected.end.of.file/" }
   - match:  { responses.2.hits.total:     1  }
   - match:  { responses.3.error.root_cause.0.type: parsing_exception }
   - match:  { responses.3.error.root_cause.0.reason: "/unknown.query.\\[unknown\\]/" }
   - match:  { responses.4.error.root_cause.0.type: illegal_argument_exception }
   - match:  { responses.4.error.root_cause.0.reason: "[rest_total_hits_as_int] cannot be used if the tracking of total hits is not accurate, got 1" }
   - match:  { responses.0.status: 200 }
-  - match:  { responses.1.status: 500 }
+  - match:  { responses.1.status: 400 }
   - match:  { responses.2.status: 200 }
   - match:  { responses.3.status: 400 }
 

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/external/response/XContentUtilsTests.java

@@ -103,8 +103,7 @@ public void testPositionParserAtTokenAfterField_ThrowsWithMalformedJSON() throws
                 XContentEOFException.class,
                 () -> XContentUtils.positionParserAtTokenAfterField(parser, missingField, errorFormat)
             );
-
-            assertThat(exception.getMessage(), containsString("Unexpected end-of-input"));
+            assertThat(exception.getMessage(), containsString("[4:1] Unexpected end of file"));
         }
     }
 

x-pack/plugin/inference/src/test/java/org/elasticsearch/xpack/inference/external/response/huggingface/HuggingFaceElserResponseEntityTests.java

@@ -309,8 +309,8 @@ public void testFails_ResponseIsInvalidJson_MissingSquareBracket() {
                 new HttpResult(mock(HttpResponse.class), responseJson.getBytes(StandardCharsets.UTF_8))
             )
         );
-
-        assertThat(thrownException.getMessage(), containsString("expected close marker for Array (start marker at"));
+        assertThat(thrownException.getMessage(), containsString("[5:1] Unexpected end of file"));
+        assertThat(thrownException.getCause().getMessage(), containsString("expected close marker for Array (start marker at"));
     }
 
     public void testFails_ResponseIsInvalidJson_MissingField() {

x-pack/plugin/ml/src/main/java/org/elasticsearch/xpack/ml/job/process/autodetect/writer/XContentRecordReader.java

@@ -8,7 +8,6 @@
 
 import org.apache.logging.log4j.Logger;
 import org.elasticsearch.ElasticsearchParseException;
-import org.elasticsearch.xcontent.XContentEOFException;
 import org.elasticsearch.xcontent.XContentParseException;
 import org.elasticsearch.xcontent.XContentParser;
 
@@ -196,7 +195,7 @@ protected void initArrays(String[] record, boolean[] gotFields) {
     protected XContentParser.Token tryNextTokenOrReadToEndOnError() throws IOException {
         try {
             return parser.nextToken();
-        } catch (XContentEOFException | XContentParseException e) {
+        } catch (XContentParseException e) {
             logger.warn("Attempting to recover from malformed JSON data.", e);
             for (int i = 0; i <= nestedLevel; ++i) {
                 readToEndOfObject();
@@ -217,7 +216,7 @@ protected void readToEndOfObject() throws IOException {
         do {
             try {
                 token = parser.nextToken();
-            } catch (XContentEOFException | XContentParseException e) {
+            } catch (XContentParseException e) {
                 ++errorCounter;
                 if (errorCounter >= PARSE_ERRORS_LIMIT) {
                     logger.error("Failed to recover from malformed JSON data.", e);