IPv4 network packet: Java parsing library

KS implementation details

License: CC0-1.0
Minimal Kaitai Struct required: 0.8

References

This page hosts a formal specification of IPv4 network packet using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime library

All parsing code for Java generated by Kaitai Struct depends on the Java runtime library. You have to install it before you can parse data.

The Java runtime library is published in the Maven Central Repository. Refer to the artifact page for instructions how to add it into your project with the build tool that you use.

Code

Parse a local file and get structure in memory:

Ipv4Packet data = Ipv4Packet.fromFile("path/to/local/file.IPv4 network packet");

Or parse structure from a byte array:

byte[] someArray = new byte[] { ... };
Ipv4Packet data = new Ipv4Packet(new ByteBufferKaitaiStream(someArray));

After that, one can get various attributes from the structure by invoking getter methods like:

data.b1() // => get b1

Java source code to parse IPv4 network packet

Ipv4Packet.java

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

import io.kaitai.struct.ByteBufferKaitaiStream;
import io.kaitai.struct.KaitaiStruct;
import io.kaitai.struct.KaitaiStream;
import java.io.IOException;
import java.util.ArrayList;

public class Ipv4Packet extends KaitaiStruct {
    public static Ipv4Packet fromFile(String fileName) throws IOException {
        return new Ipv4Packet(new ByteBufferKaitaiStream(fileName));
    }

    public Ipv4Packet(KaitaiStream _io) {
        this(_io, null, null);
    }

    public Ipv4Packet(KaitaiStream _io, KaitaiStruct _parent) {
        this(_io, _parent, null);
    }

    public Ipv4Packet(KaitaiStream _io, KaitaiStruct _parent, Ipv4Packet _root) {
        super(_io);
        this._parent = _parent;
        this._root = _root == null ? this : _root;
        _read();
    }
    private void _read() {
        this.b1 = this._io.readU1();
        this.b2 = this._io.readU1();
        this.totalLength = this._io.readU2be();
        this.identification = this._io.readU2be();
        this.b67 = this._io.readU2be();
        this.ttl = this._io.readU1();
        this.protocol = this._io.readU1();
        this.headerChecksum = this._io.readU2be();
        this.srcIpAddr = this._io.readBytes(4);
        this.dstIpAddr = this._io.readBytes(4);
        this._raw_options = this._io.readBytes((ihlBytes() - 20));
        KaitaiStream _io__raw_options = new ByteBufferKaitaiStream(_raw_options);
        this.options = new Ipv4Options(_io__raw_options, this, _root);
        this._raw_body = this._io.readBytes((totalLength() - ihlBytes()));
        KaitaiStream _io__raw_body = new ByteBufferKaitaiStream(_raw_body);
        this.body = new ProtocolBody(_io__raw_body, protocol());
    }
    public static class Ipv4Options extends KaitaiStruct {
        public static Ipv4Options fromFile(String fileName) throws IOException {
            return new Ipv4Options(new ByteBufferKaitaiStream(fileName));
        }

        public Ipv4Options(KaitaiStream _io) {
            this(_io, null, null);
        }

        public Ipv4Options(KaitaiStream _io, Ipv4Packet _parent) {
            this(_io, _parent, null);
        }

        public Ipv4Options(KaitaiStream _io, Ipv4Packet _parent, Ipv4Packet _root) {
            super(_io);
            this._parent = _parent;
            this._root = _root;
            _read();
        }
        private void _read() {
            this.entries = new ArrayList<Ipv4Option>();
            {
                int i = 0;
                while (!this._io.isEof()) {
                    this.entries.add(new Ipv4Option(this._io, this, _root));
                    i++;
                }
            }
        }
        private ArrayList<Ipv4Option> entries;
        private Ipv4Packet _root;
        private Ipv4Packet _parent;
        public ArrayList<Ipv4Option> entries() { return entries; }
        public Ipv4Packet _root() { return _root; }
        public Ipv4Packet _parent() { return _parent; }
    }
    public static class Ipv4Option extends KaitaiStruct {
        public static Ipv4Option fromFile(String fileName) throws IOException {
            return new Ipv4Option(new ByteBufferKaitaiStream(fileName));
        }

        public Ipv4Option(KaitaiStream _io) {
            this(_io, null, null);
        }

        public Ipv4Option(KaitaiStream _io, Ipv4Packet.Ipv4Options _parent) {
            this(_io, _parent, null);
        }

        public Ipv4Option(KaitaiStream _io, Ipv4Packet.Ipv4Options _parent, Ipv4Packet _root) {
            super(_io);
            this._parent = _parent;
            this._root = _root;
            _read();
        }
        private void _read() {
            this.b1 = this._io.readU1();
            this.len = this._io.readU1();
            this.body = this._io.readBytes((len() > 2 ? (len() - 2) : 0));
        }
        private Integer copy;
        public Integer copy() {
            if (this.copy != null)
                return this.copy;
            int _tmp = (int) (((b1() & 128) >> 7));
            this.copy = _tmp;
            return this.copy;
        }
        private Integer optClass;
        public Integer optClass() {
            if (this.optClass != null)
                return this.optClass;
            int _tmp = (int) (((b1() & 96) >> 5));
            this.optClass = _tmp;
            return this.optClass;
        }
        private Integer number;
        public Integer number() {
            if (this.number != null)
                return this.number;
            int _tmp = (int) ((b1() & 31));
            this.number = _tmp;
            return this.number;
        }
        private int b1;
        private int len;
        private byte[] body;
        private Ipv4Packet _root;
        private Ipv4Packet.Ipv4Options _parent;
        public int b1() { return b1; }
        public int len() { return len; }
        public byte[] body() { return body; }
        public Ipv4Packet _root() { return _root; }
        public Ipv4Packet.Ipv4Options _parent() { return _parent; }
    }
    private Integer version;
    public Integer version() {
        if (this.version != null)
            return this.version;
        int _tmp = (int) (((b1() & 240) >> 4));
        this.version = _tmp;
        return this.version;
    }
    private Integer ihl;
    public Integer ihl() {
        if (this.ihl != null)
            return this.ihl;
        int _tmp = (int) ((b1() & 15));
        this.ihl = _tmp;
        return this.ihl;
    }
    private Integer ihlBytes;
    public Integer ihlBytes() {
        if (this.ihlBytes != null)
            return this.ihlBytes;
        int _tmp = (int) ((ihl() * 4));
        this.ihlBytes = _tmp;
        return this.ihlBytes;
    }
    private int b1;
    private int b2;
    private int totalLength;
    private int identification;
    private int b67;
    private int ttl;
    private int protocol;
    private int headerChecksum;
    private byte[] srcIpAddr;
    private byte[] dstIpAddr;
    private Ipv4Options options;
    private ProtocolBody body;
    private Ipv4Packet _root;
    private KaitaiStruct _parent;
    private byte[] _raw_options;
    private byte[] _raw_body;
    public int b1() { return b1; }
    public int b2() { return b2; }
    public int totalLength() { return totalLength; }
    public int identification() { return identification; }
    public int b67() { return b67; }
    public int ttl() { return ttl; }
    public int protocol() { return protocol; }
    public int headerChecksum() { return headerChecksum; }
    public byte[] srcIpAddr() { return srcIpAddr; }
    public byte[] dstIpAddr() { return dstIpAddr; }
    public Ipv4Options options() { return options; }
    public ProtocolBody body() { return body; }
    public Ipv4Packet _root() { return _root; }
    public KaitaiStruct _parent() { return _parent; }
    public byte[] _raw_options() { return _raw_options; }
    public byte[] _raw_body() { return _raw_body; }
}