From 68b6a6197bb853895bc6ac184578bb3899045929 Mon Sep 17 00:00:00 2001
From: James Nylen <jnylen0@git.wordpress.org>
Date: Tue, 13 Dec 2016 03:33:14 +0000
Subject: [PATCH] REST API: Do not error on empty JSON body

It's fairly common for clients to send `Content-Type: application/json` with an
empty body.  While technically not valid JSON, we've historically supported
this behaviour, so it shouldn't cause an error.

Props JPry.
Fixes #39150.


git-svn-id: https://develop.svn.wordpress.org/trunk@39594 602fd350-edb4-49c9-b593-d223f7449a82
---
 .../rest-api/class-wp-rest-request.php            |  7 ++++++-
 tests/phpunit/tests/rest-api/rest-request.php     | 15 +++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/wp-includes/rest-api/class-wp-rest-request.php b/src/wp-includes/rest-api/class-wp-rest-request.php
index d37ab6175d..4dd0dc2090 100644
--- a/src/wp-includes/rest-api/class-wp-rest-request.php
+++ b/src/wp-includes/rest-api/class-wp-rest-request.php
@@ -669,7 +669,12 @@ class WP_REST_Request implements ArrayAccess {
 			return true;
 		}
 
-		$params = json_decode( $this->get_body(), true );
+		$body = $this->get_body();
+		if ( empty( $body ) ) {
+			return true;
+		}
+
+		$params = json_decode( $body, true );
 
 		/*
 		 * Check for a parsing error.
diff --git a/tests/phpunit/tests/rest-api/rest-request.php b/tests/phpunit/tests/rest-api/rest-request.php
index dd87e2b5c0..7953f65bad 100644
--- a/tests/phpunit/tests/rest-api/rest-request.php
+++ b/tests/phpunit/tests/rest-api/rest-request.php
@@ -10,6 +10,8 @@
  * @group restapi
  */
 class Tests_REST_Request extends WP_UnitTestCase {
+	public $request;
+
 	public function setUp() {
 		parent::setUp();
 
@@ -450,6 +452,19 @@ class Tests_REST_Request extends WP_UnitTestCase {
 		$this->assertEquals( JSON_ERROR_SYNTAX, $data['json_error_code'] );
 	}
 
+
+	public function test_has_valid_params_empty_json_no_error() {
+		if ( version_compare( PHP_VERSION, '5.3', '<' ) ) {
+			return $this->markTestSkipped( 'JSON validation is only available for PHP 5.3+' );
+		}
+
+		$this->request->set_header( 'Content-Type', 'application/json' );
+		$this->request->set_body( '' );
+
+		$valid = $this->request->has_valid_params();
+		$this->assertNotWPError( $valid );
+	}
+
 	public function test_has_multiple_invalid_params_validate_callback() {
 		$this->request->set_url_params( array(
 			'someinteger' => '123',