IXR_Message::parse() WordPress Method

    function parse()
    {
        if ( ! function_exists( 'xml_parser_create' ) ) {
            trigger_error( __( "PHP's XML extension is not available. Please contact your hosting provider to enable PHP's XML extension." ) );
            return false;
        }

        // first remove the XML declaration
        // merged from WP #10698 - this method avoids the RAM usage of preg_replace on very large messages
        $header = preg_replace( '/<\?xml.*?\?'.'>/s', '', substr( $this->message, 0, 100 ), 1 );
        $this->message = trim( substr_replace( $this->message, $header, 0, 100 ) );
        if ( '' == $this->message ) {
            return false;
        }

        // Then remove the DOCTYPE
        $header = preg_replace( '/^<!DOCTYPE[^>]*+>/i', '', substr( $this->message, 0, 200 ), 1 );
        $this->message = trim( substr_replace( $this->message, $header, 0, 200 ) );
        if ( '' == $this->message ) {
            return false;
        }

        // Check that the root tag is valid
        $root_tag = substr( $this->message, 0, strcspn( substr( $this->message, 0, 20 ), "> \t\r\n" ) );
        if ( '<!DOCTYPE' === strtoupper( $root_tag ) ) {
            return false;
        }
        if ( ! in_array( $root_tag, array( '<methodCall', '<methodResponse', '<fault' ) ) ) {
            return false;
        }

        // Bail if there are too many elements to parse
        $element_limit = 30000;
        if ( function_exists( 'apply_filters' ) ) {
            /**
             * Filters the number of elements to parse in an XML-RPC response.
             *
             * @since 4.0.0
             *
             * @param int $element_limit Default elements limit.
             */
            $element_limit = apply_filters( 'xmlrpc_element_limit', $element_limit );
        }
        if ( $element_limit && 2 * $element_limit < substr_count( $this->message, '<' ) ) {
            return false;
        }

        $this->_parser = xml_parser_create();
        // Set XML parser to take the case of tags in to account
        xml_parser_set_option($this->_parser, XML_OPTION_CASE_FOLDING, false);
        // Set XML parser callback functions
        xml_set_object($this->_parser, $this);
        xml_set_element_handler($this->_parser, 'tag_open', 'tag_close');
        xml_set_character_data_handler($this->_parser, 'cdata');

        // 256Kb, parse in chunks to avoid the RAM usage on very large messages
        $chunk_size = 262144;

        /**
         * Filters the chunk size that can be used to parse an XML-RPC response message.
         *
         * @since 4.4.0
         *
         * @param int $chunk_size Chunk size to parse in bytes.
         */
        $chunk_size = apply_filters( 'xmlrpc_chunk_parsing_size', $chunk_size );

        $final = false;

        do {
            if (strlen($this->message) <= $chunk_size) {
                $final = true;
            }

            $part = substr($this->message, 0, $chunk_size);
            $this->message = substr($this->message, $chunk_size);

            if (!xml_parse($this->_parser, $part, $final)) {
                xml_parser_free($this->_parser);
                unset($this->_parser);
                return false;
            }

            if ($final) {
                break;
            }
        } while (true);

        xml_parser_free($this->_parser);
        unset($this->_parser);

        // Grab the error messages, if any
        if ($this->messageType == 'fault') {
            $this->faultCode = $this->params[0]['faultCode'];
            $this->faultString = $this->params[0]['faultString'];
        }
        return true;
    }