ICMP network packet: PHP parsing library

<?php
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

namespace {
    class IcmpPacket extends \Kaitai\Struct\Struct {
        public function __construct(\Kaitai\Struct\Stream $_io, \Kaitai\Struct\Struct $_parent = null, \IcmpPacket $_root = null) {
            parent::__construct($_io, $_parent, $_root);
            $this->_read();
        }

        private function _read() {
            $this->_m_icmpType = $this->_io->readU1();
            if ($this->icmpType() == \IcmpPacket\IcmpTypeEnum::DESTINATION_UNREACHABLE) {
                $this->_m_destinationUnreachable = new \IcmpPacket\DestinationUnreachableMsg($this->_io, $this, $this->_root);
            }
            if ($this->icmpType() == \IcmpPacket\IcmpTypeEnum::TIME_EXCEEDED) {
                $this->_m_timeExceeded = new \IcmpPacket\TimeExceededMsg($this->_io, $this, $this->_root);
            }
            if ( (($this->icmpType() == \IcmpPacket\IcmpTypeEnum::ECHO) || ($this->icmpType() == \IcmpPacket\IcmpTypeEnum::ECHO_REPLY)) ) {
                $this->_m_echo = new \IcmpPacket\EchoMsg($this->_io, $this, $this->_root);
            }
        }
        protected $_m_icmpType;
        protected $_m_destinationUnreachable;
        protected $_m_timeExceeded;
        protected $_m_echo;
        public function icmpType() { return $this->_m_icmpType; }
        public function destinationUnreachable() { return $this->_m_destinationUnreachable; }
        public function timeExceeded() { return $this->_m_timeExceeded; }
        public function echo() { return $this->_m_echo; }
    }
}

namespace IcmpPacket {
    class DestinationUnreachableMsg extends \Kaitai\Struct\Struct {
        public function __construct(\Kaitai\Struct\Stream $_io, \IcmpPacket $_parent = null, \IcmpPacket $_root = null) {
            parent::__construct($_io, $_parent, $_root);
            $this->_read();
        }

        private function _read() {
            $this->_m_code = $this->_io->readU1();
            $this->_m_checksum = $this->_io->readU2be();
        }
        protected $_m_code;
        protected $_m_checksum;
        public function code() { return $this->_m_code; }
        public function checksum() { return $this->_m_checksum; }
    }
}

namespace IcmpPacket\DestinationUnreachableMsg {
    class DestinationUnreachableCode {
        const NET_UNREACHABLE = 0;
        const HOST_UNREACHABLE = 1;
        const PROTOCOL_UNREACHABLE = 2;
        const PORT_UNREACHABLE = 3;
        const FRAGMENTATION_NEEDED_AND_DF_SET = 4;
        const SOURCE_ROUTE_FAILED = 5;
        const DST_NET_UNKOWN = 6;
        const SDT_HOST_UNKOWN = 7;
        const SRC_ISOLATED = 8;
        const NET_PROHIBITED_BY_ADMIN = 9;
        const HOST_PROHIBITED_BY_ADMIN = 10;
        const NET_UNREACHABLE_FOR_TOS = 11;
        const HOST_UNREACHABLE_FOR_TOS = 12;
        const COMMUNICATION_PROHIBITED_BY_ADMIN = 13;
        const HOST_PRECEDENCE_VIOLATION = 14;
        const PRECEDENCE_CUTTOFF_IN_EFFECT = 15;
    }
}

namespace IcmpPacket {
    class TimeExceededMsg extends \Kaitai\Struct\Struct {
        public function __construct(\Kaitai\Struct\Stream $_io, \IcmpPacket $_parent = null, \IcmpPacket $_root = null) {
            parent::__construct($_io, $_parent, $_root);
            $this->_read();
        }

        private function _read() {
            $this->_m_code = $this->_io->readU1();
            $this->_m_checksum = $this->_io->readU2be();
        }
        protected $_m_code;
        protected $_m_checksum;
        public function code() { return $this->_m_code; }
        public function checksum() { return $this->_m_checksum; }
    }
}

namespace IcmpPacket\TimeExceededMsg {
    class TimeExceededCode {
        const TIME_TO_LIVE_EXCEEDED_IN_TRANSIT = 0;
        const FRAGMENT_REASSEMBLY_TIME_EXCEEDED = 1;
    }
}

namespace IcmpPacket {
    class EchoMsg extends \Kaitai\Struct\Struct {
        public function __construct(\Kaitai\Struct\Stream $_io, \IcmpPacket $_parent = null, \IcmpPacket $_root = null) {
            parent::__construct($_io, $_parent, $_root);
            $this->_read();
        }

        private function _read() {
            $this->_m_code = $this->_io->readBytes(1);
            if (!($this->code() == "\x00")) {
                throw new \Kaitai\Struct\Error\ValidationNotEqualError("\x00", $this->code(), $this->_io(), "/types/echo_msg/seq/0");
            }
            $this->_m_checksum = $this->_io->readU2be();
            $this->_m_identifier = $this->_io->readU2be();
            $this->_m_seqNum = $this->_io->readU2be();
            $this->_m_data = $this->_io->readBytesFull();
        }
        protected $_m_code;
        protected $_m_checksum;
        protected $_m_identifier;
        protected $_m_seqNum;
        protected $_m_data;
        public function code() { return $this->_m_code; }
        public function checksum() { return $this->_m_checksum; }
        public function identifier() { return $this->_m_identifier; }
        public function seqNum() { return $this->_m_seqNum; }
        public function data() { return $this->_m_data; }
    }
}

namespace IcmpPacket {
    class IcmpTypeEnum {
        const ECHO_REPLY = 0;
        const DESTINATION_UNREACHABLE = 3;
        const SOURCE_QUENCH = 4;
        const REDIRECT = 5;
        const ECHO = 8;
        const TIME_EXCEEDED = 11;
    }
}