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, 39 insertions, 0 deletions

diff --git a/core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java b/core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
index df34ec726f..189e9d3c8d 100644
--- a/core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
+++ b/core/src/main/java/org/elasticsearch/common/xcontent/XContentBuilder.java
@@ -964,21 +964,60 @@ public final class XContentBuilder implements BytesStream, Releasable, Flushable
     // Raw fields
     //////////////////////////////////
 
+    /**
+     * Writes a raw field with the value taken from the bytes in the stream
+     * @deprecated use {@link #rawField(String, InputStream, XContentType)} to avoid content type auto-detection
+     */
+    @Deprecated
     public XContentBuilder rawField(String name, InputStream value) throws IOException {
         generator.writeRawField(name, value);
         return this;
     }
 
+    /**
+     * Writes a raw field with the value taken from the bytes in the stream
+     */
+    public XContentBuilder rawField(String name, InputStream value, XContentType contentType) throws IOException {
+        generator.writeRawField(name, value, contentType);
+        return this;
+    }
+
+    /**
+     * Writes a raw field with the given bytes as the value
+     * @deprecated use {@link #rawField(String name, BytesReference, XContentType)} to avoid content type auto-detection
+     */
+    @Deprecated
     public XContentBuilder rawField(String name, BytesReference value) throws IOException {
         generator.writeRawField(name, value);
         return this;
     }
 
+    /**
+     * Writes a raw field with the given bytes as the value
+     */
+    public XContentBuilder rawField(String name, BytesReference value, XContentType contentType) throws IOException {
+        generator.writeRawField(name, value, contentType);
+        return this;
+    }
+
+    /**
+     * Writes a value with the source coming directly from the bytes
+     * @deprecated use {@link #rawValue(BytesReference, XContentType)} to avoid content type auto-detection
+     */
+    @Deprecated
     public XContentBuilder rawValue(BytesReference value) throws IOException {
         generator.writeRawValue(value);
         return this;
     }
 
+    /**
+     * Writes a value with the source coming directly from the bytes
+     */
+    public XContentBuilder rawValue(BytesReference value, XContentType contentType) throws IOException {
+        generator.writeRawValue(value, contentType);
+        return this;
+    }
+
     public XContentBuilder copyCurrentStructure(XContentParser parser) throws IOException {
         generator.copyCurrentStructure(parser);
         return this;