TCP (Transmission Control Protocol) segment: PHP parsing library

TCP is one of the core Internet protocols on transport layer (AKA OSI layer 4), providing stateful connections with error checking, guarantees of delivery, order of segments and avoidance of duplicate delivery.

KS implementation details

License: CC0-1.0
Minimal Kaitai Struct required: 0.1

References

This page hosts a formal specification of TCP (Transmission Control Protocol) segment using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

PHP source code to parse TCP (Transmission Control Protocol) segment

TcpSegment.php

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

/**
 * TCP is one of the core Internet protocols on transport layer (AKA
 * OSI layer 4), providing stateful connections with error checking,
 * guarantees of delivery, order of segments and avoidance of duplicate
 * delivery.
 */

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

        private function _read() {
            $this->_m_srcPort = $this->_io->readU2be();
            $this->_m_dstPort = $this->_io->readU2be();
            $this->_m_seqNum = $this->_io->readU4be();
            $this->_m_ackNum = $this->_io->readU4be();
            $this->_m_dataOffset = $this->_io->readBitsIntBe(4);
            $this->_m_reserved = $this->_io->readBitsIntBe(4);
            $this->_io->alignToByte();
            $this->_m_flags = new \TcpSegment\Flags($this->_io, $this, $this->_root);
            $this->_m_windowSize = $this->_io->readU2be();
            $this->_m_checksum = $this->_io->readU2be();
            $this->_m_urgentPointer = $this->_io->readU2be();
            if ((($this->dataOffset() * 4) - 20) != 0) {
                $this->_m_options = $this->_io->readBytes((($this->dataOffset() * 4) - 20));
            }
            $this->_m_body = $this->_io->readBytesFull();
        }
        protected $_m_srcPort;
        protected $_m_dstPort;
        protected $_m_seqNum;
        protected $_m_ackNum;
        protected $_m_dataOffset;
        protected $_m_reserved;
        protected $_m_flags;
        protected $_m_windowSize;
        protected $_m_checksum;
        protected $_m_urgentPointer;
        protected $_m_options;
        protected $_m_body;

        /**
         * Source port
         */
        public function srcPort() { return $this->_m_srcPort; }

        /**
         * Destination port
         */
        public function dstPort() { return $this->_m_dstPort; }

        /**
         * Sequence number
         */
        public function seqNum() { return $this->_m_seqNum; }

        /**
         * Acknowledgment number
         */
        public function ackNum() { return $this->_m_ackNum; }

        /**
         * Data offset (in 32-bit words from the beginning of this type, normally 32 or can be extended if there are any TCP options or padding is present)
         */
        public function dataOffset() { return $this->_m_dataOffset; }
        public function reserved() { return $this->_m_reserved; }
        public function flags() { return $this->_m_flags; }
        public function windowSize() { return $this->_m_windowSize; }
        public function checksum() { return $this->_m_checksum; }
        public function urgentPointer() { return $this->_m_urgentPointer; }
        public function options() { return $this->_m_options; }
        public function body() { return $this->_m_body; }
    }
}

/**
 * TCP header flags as defined "TCP Header Flags" registry.
 */

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

        private function _read() {
            $this->_m_cwr = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_ece = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_urg = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_ack = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_psh = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_rst = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_syn = $this->_io->readBitsIntBe(1) != 0;
            $this->_m_fin = $this->_io->readBitsIntBe(1) != 0;
        }
        protected $_m_cwr;
        protected $_m_ece;
        protected $_m_urg;
        protected $_m_ack;
        protected $_m_psh;
        protected $_m_rst;
        protected $_m_syn;
        protected $_m_fin;

        /**
         * Congestion Window Reduced
         */
        public function cwr() { return $this->_m_cwr; }

        /**
         * ECN-Echo
         */
        public function ece() { return $this->_m_ece; }

        /**
         * Urgent pointer field is significant
         */
        public function urg() { return $this->_m_urg; }

        /**
         * Acknowledgment field is significant
         */
        public function ack() { return $this->_m_ack; }

        /**
         * Push function
         */
        public function psh() { return $this->_m_psh; }

        /**
         * Reset the connection
         */
        public function rst() { return $this->_m_rst; }

        /**
         * Synchronize sequence numbers
         */
        public function syn() { return $this->_m_syn; }

        /**
         * No more data from sender
         */
        public function fin() { return $this->_m_fin; }
    }
}