Optionally require a valid content type for all rest requests with content (#22691)

This change adds a strict mode for xcontent parsing on the rest layer. The strict mode will be off by default for 5.x and in a separate commit will be enabled by default for 6.0. The strict mode, which can be enabled by setting `http.content_type.required: true` in 5.x, will require that all incoming rest requests have a valid and supported content type header before the request is dispatched. In the non-strict mode, the Content-Type header will be inspected and if it is not present or not valid, we will continue with auto detection of content like we have done previously.

The content type header is parsed to the matching XContentType value with the only exception being for plain text requests. This value is then passed on with the content bytes so that we can reduce the number of places where we need to auto-detect the content type.

As part of this, many transport requests and builders were updated to provide methods that
accepted the XContentType along with the bytes and the methods that would rely on auto-detection have been deprecated.

In the non-strict mode, deprecation warnings are issued whenever a request with body doesn't provide the Content-Type header.

See #19388 

1 files changed, 26 insertions, 18 deletions

diff --git a/test/framework/src/main/java/org/elasticsearch/test/rest/FakeRestRequest.java b/test/framework/src/main/java/org/elasticsearch/test/rest/FakeRestRequest.java
index ae8c4c82c4..83caf0293e 100644
--- a/test/framework/src/main/java/org/elasticsearch/test/rest/FakeRestRequest.java
+++ b/test/framework/src/main/java/org/elasticsearch/test/rest/FakeRestRequest.java
@@ -21,28 +21,31 @@ package org.elasticsearch.test.rest;
 
 import org.elasticsearch.common.bytes.BytesReference;
 import org.elasticsearch.common.xcontent.NamedXContentRegistry;
+import org.elasticsearch.common.xcontent.XContentType;
 import org.elasticsearch.rest.RestRequest;
 
+import java.net.SocketAddress;
+import java.util.Collections;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 public class FakeRestRequest extends RestRequest {
 
-    private final Map<String, String> headers;
     private final BytesReference content;
     private final Method method;
-
+    private final SocketAddress remoteAddress;
 
     public FakeRestRequest() {
-        this(NamedXContentRegistry.EMPTY, new HashMap<>(), new HashMap<>(), null, Method.GET, "/");
+        this(NamedXContentRegistry.EMPTY, new HashMap<>(), new HashMap<>(), null, Method.GET, "/", null);
     }
 
-    private FakeRestRequest(NamedXContentRegistry xContentRegistry, Map<String, String> headers, Map<String, String> params,
-            BytesReference content, Method method, String path) {
-        super(xContentRegistry, params, path);
-        this.headers = headers;
+    private FakeRestRequest(NamedXContentRegistry xContentRegistry, Map<String, List<String>> headers, Map<String, String> params,
+                            BytesReference content, Method method, String path, SocketAddress remoteAddress) {
+        super(xContentRegistry, params, path, headers);
         this.content = content;
         this.method = method;
+        this.remoteAddress = remoteAddress;
     }
 
     @Override
@@ -66,19 +69,14 @@ public class FakeRestRequest extends RestRequest {
     }
 
     @Override
-    public String header(String name) {
-        return headers.get(name);
-    }
-
-    @Override
-    public Iterable<Map.Entry<String, String>> headers() {
-        return headers.entrySet();
+    public SocketAddress getRemoteAddress() {
+        return remoteAddress;
     }
 
     public static class Builder {
         private final NamedXContentRegistry xContentRegistry;
 
-        private Map<String, String> headers = new HashMap<>();
+        private Map<String, List<String>> headers = new HashMap<>();
 
         private Map<String, String> params = new HashMap<>();
 
@@ -88,11 +86,13 @@ public class FakeRestRequest extends RestRequest {
 
         private Method method = Method.GET;
 
+        private SocketAddress address = null;
+
         public Builder(NamedXContentRegistry xContentRegistry) {
             this.xContentRegistry = xContentRegistry;
         }
 
-        public Builder withHeaders(Map<String, String> headers) {
+        public Builder withHeaders(Map<String, List<String>> headers) {
             this.headers = headers;
             return this;
         }
@@ -102,8 +102,11 @@ public class FakeRestRequest extends RestRequest {
             return this;
         }
 
-        public Builder withContent(BytesReference content) {
+        public Builder withContent(BytesReference content, XContentType xContentType) {
             this.content = content;
+            if (xContentType != null) {
+                headers.put("Content-Type", Collections.singletonList(xContentType.mediaType()));
+            }
             return this;
         }
 
@@ -117,8 +120,13 @@ public class FakeRestRequest extends RestRequest {
             return this;
         }
 
+        public Builder withRemoteAddress(SocketAddress address) {
+            this.address = address;
+            return this;
+        }
+
         public FakeRestRequest build() {
-            return new FakeRestRequest(xContentRegistry, headers, params, content, method, path);
+            return new FakeRestRequest(xContentRegistry, headers, params, content, method, path, address);
         }
 
     }