From eb630e599d5aa02872153a3be8a1e7985824906e Mon Sep 17 00:00:00 2001
From: Przemyslaw Gomulka <przemyslaw.gomulka@elastic.co>
Date: Fri, 2 Oct 2020 09:17:11 +0200
Subject: [PATCH] Allow passing versioned media types to 7.x server (#63071)

7.x client can pass media type with a version which will return a 7.x
version of the api in ES 8.
In ES server 7 this media type shoulld be accepted but it serve the same
version of the API (7x)
relates #61427
---
 .../common/xcontent/XContentType.java         | 19 +++++++++++++++++++
 .../common/xcontent/XContentTypeTests.java    | 17 +++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/libs/x-content/src/main/java/org/elasticsearch/common/xcontent/XContentType.java b/libs/x-content/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
index 606284f0462..d058ff76087 100644
--- a/libs/x-content/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
+++ b/libs/x-content/src/main/java/org/elasticsearch/common/xcontent/XContentType.java
@@ -124,6 +124,8 @@ public enum XContentType {
         if (mediaType == null) {
             return null;
         }
+
+        mediaType = removeVersionInMediaType(mediaType);
         for (XContentType type : values()) {
             if (isSameMediaTypeOrFormatAs(mediaType, type)) {
                 return type;
@@ -137,6 +139,23 @@ public enum XContentType {
         return null;
     }
 
+    /**
+     * Clients compatible with ES 7.x might start sending media types with versioned media type
+     * in a form of application/vnd.elasticsearch+json;compatible-with=7.
+     * This has to be removed in order to be used in 7.x server.
+     * The same client connecting using that media type will be able to communicate with ES 8 thanks to compatible API.
+     * @param mediaType - a media type used on Content-Type header, might contain versioned media type.
+     *
+     * @return a media type string without
+     */
+    private static String removeVersionInMediaType(String mediaType) {
+        if (mediaType.contains("vnd.elasticsearch")) {
+            return mediaType.replaceAll("vnd.elasticsearch\\+", "")
+                .replaceAll("\\s*;\\s*compatible-with=\\d+", "");
+        }
+        return mediaType;
+    }
+
     /**
      * Attempts to match the given media type with the known {@link XContentType} values. This match is done in a case-insensitive manner.
      * The provided media type should not include any parameters. This method is suitable for parsing part of the {@code Content-Type}
diff --git a/server/src/test/java/org/elasticsearch/common/xcontent/XContentTypeTests.java b/server/src/test/java/org/elasticsearch/common/xcontent/XContentTypeTests.java
index 47a470e2cea..0dc2be69348 100644
--- a/server/src/test/java/org/elasticsearch/common/xcontent/XContentTypeTests.java
+++ b/server/src/test/java/org/elasticsearch/common/xcontent/XContentTypeTests.java
@@ -26,6 +26,7 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.nullValue;
 
 public class XContentTypeTests extends ESTestCase {
+
     public void testFromJson() throws Exception {
         String mediaType = "application/json";
         XContentType expectedXContentType = XContentType.JSON;
@@ -84,4 +85,20 @@ public class XContentTypeTests extends ESTestCase {
         assertThat(XContentType.fromMediaTypeOrFormat("text/plain"), nullValue());
         assertThat(XContentType.fromMediaTypeOrFormat("gobbly;goop"), nullValue());
     }
+
+    public void testVersionedMediaType() throws Exception {
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+json;compatible-with=7"),
+            equalTo(XContentType.JSON));
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+yaml;compatible-with=7"),
+            equalTo(XContentType.YAML));
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+cbor;compatible-with=7"),
+            equalTo(XContentType.CBOR));
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+smile;compatible-with=7"),
+            equalTo(XContentType.SMILE));
+
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+json ;compatible-with=7"),
+            equalTo(XContentType.JSON));
+        assertThat(XContentType.fromMediaTypeOrFormat("application/vnd.elasticsearch+json ;compatible-with=7;charset=utf-8"),
+            equalTo(XContentType.JSON));
+    }
 }