Merge pull request #461 from WP-API/json-error-reporting

Check for JSON encoding/decoding errors

lib/class-wp-json-server.php

@@ -285,6 +285,13 @@ public function serve_request( $path = null ) {
 
 			$result = json_encode( $this->prepare_response( $result ) );
 
+			$json_error_message = $this->get_json_last_error();
+			if ( $json_error_message ) {
+				$json_error_obj = new WP_Error( 'json_encode_error', $json_error_message, array( 'status' => 500 ) );
+				$result = $this->error_to_response( $json_error_obj );
+				$result = json_encode( $result->data[0] );
+			}
+
 			if ( isset( $_GET['_jsonp'] ) ) {
 				// Prepend '/**/' to mitigate possible JSONP Flash attacks
 				// http://miki.it/blog/2014/7/8/abusing-jsonp-with-rosetta-flash/
@@ -390,6 +397,12 @@ public function dispatch() {
 				if ( $supported & self::ACCEPT_JSON ) {
 					$data = json_decode( $this->get_raw_data(), true );
 
+					// test for json_decode() error
+					$json_error_message = $this->get_json_last_error();
+					if ( $json_error_message ) {
+						return new WP_Error( 'json_decode_error', $json_error_message, array( 'status' => 500 ) );
+					}
+
 					if ( $data !== null ) {
 						$args = array_merge( $args, array( 'data' => $data ) );
 					}
@@ -427,6 +440,26 @@ public function dispatch() {
 		return new WP_Error( 'json_no_route', __( 'No route was found matching the URL and request method' ), array( 'status' => 404 ) );
 	}
 
+	/**
+	 * Returns if an error occurred during most recent JSON encode/decode
+	 * Strings to be translated will be in format like "Encoding error: Maximum stack depth exceeded"
+	 *
+	 * @return boolean|string Boolean false or string error message
+	 */
+	protected function get_json_last_error( ) {
+		// see https://core.trac.wordpress.org/ticket/27799
+		if ( ! function_exists( 'json_last_error' ) ) {
+			return false;
+		}
+
+		$last_error_code = json_last_error();
+		if ( ( defined( 'JSON_ERROR_NONE' ) && $last_error_code === JSON_ERROR_NONE ) || empty( $last_error_code ) ) {
+			return false;
+		}
+
+		return json_last_error_msg();
+	}
+
 	/**
 	 * Sort parameters by order specified in method declaration
 	 *

plugin.php

@@ -697,3 +697,56 @@ function json_handle_options_request( $response, $handler ) {
 
 	return $response;
 }
+
+if ( ! function_exists( 'json_last_error_msg' ) ):
+/**
+ * Returns the error string of the last json_encode() or json_decode() call
+ *
+ * @internal This is a compatibility function for PHP <5.5
+ *
+ * @return boolean|string Returns the error message on success, "No Error" if no error has occurred, or FALSE on failure.
+ */
+function json_last_error_msg() {
+	// see https://core.trac.wordpress.org/ticket/27799
+	if ( ! function_exists( 'json_last_error' ) ) {
+		return false;
+	}
+
+	$last_error_code = json_last_error();
+
+	// just in case JSON_ERROR_NONE is not defined
+	$error_code_none = defined( 'JSON_ERROR_NONE' ) ? JSON_ERROR_NONE : 0;
+
+	switch ( true ) {
+		case $last_error_code === $error_code_none:
+			return 'No error';
+
+		case defined( 'JSON_ERROR_DEPTH' ) && JSON_ERROR_DEPTH === $last_error_code:
+			return 'Maximum stack depth exceeded';
+
+		case defined( 'JSON_ERROR_STATE_MISMATCH' ) && JSON_ERROR_STATE_MISMATCH === $last_error_code:
+			return 'State mismatch (invalid or malformed JSON)';
+
+		case defined( 'JSON_ERROR_CTRL_CHAR' ) && JSON_ERROR_CTRL_CHAR === $last_error_code:
+			return 'Control character error, possibly incorrectly encoded';
+
+		case defined( 'JSON_ERROR_SYNTAX' ) && JSON_ERROR_SYNTAX === $last_error_code:
+			return 'Syntax error';
+
+		case defined( 'JSON_ERROR_UTF8' ) && JSON_ERROR_UTF8 === $last_error_code:
+			return 'Malformed UTF-8 characters, possibly incorrectly encoded';
+
+		case defined( 'JSON_ERROR_RECURSION' ) && JSON_ERROR_RECURSION === $last_error_code:
+			return 'Recursion detected';
+
+		case defined( 'JSON_ERROR_INF_OR_NAN' ) && JSON_ERROR_INF_OR_NAN === $last_error_code:
+			return 'Inf and NaN cannot be JSON encoded';
+
+		case defined( 'JSON_ERROR_UNSUPPORTED_TYPE' ) && JSON_ERROR_UNSUPPORTED_TYPE === $last_error_code:
+			return 'Type is not supported';
+
+		default:
+			return 'An unknown error occurred';
+	}
+}
+endif;