Readme.md

This project is not maintained any more.

Feel free to fork it. If you have an active fork you want to be linked here you can contact me.

kaitaigo

kaitaigo is a compiler and runtime to create Go parsers from Kaitai Struct files.

Installation

go get dfir.software/kaitaigo

Usage

First we need a .ksy file. We take this simple example, but there are many more.

# my_format.ksy
meta:
  id: my_format
seq:
  - id: data_size
    type: u1
  - id: data
    size: data_size

To create the Go code we use the kaitaigo command: kaitaigo my_format.ksy. This creates the ready to use my_format.ksy.go.

The parser can be used in other scripts like the following. Change package in my_format.ksy.go to main. Afterward you can run the script and use our new parser with go run main.go my_format.ksy.go.

// main.go
package main

import (
	"bytes"
	"log"
)

func main() {
	f := bytes.NewReader([]byte("\x05Hello world!"))
	var r MyFormat
	err := r.Decode(f) // Decode takes any io.ReadSeeker
	if err != nil {
		log.Fatal(err)
	}
	log.Print(string(r.Data())) // Prints "Hello"
}

---

kaitaigo features

This is not the official kaitai compiler. The official kaitai compiler contains go support as well. More information in the issue for Go language support.

Supported kaitai features:

• Type specification
  • meta
    • endianess*
  • doc
  • seq
  • instances
  • enums
• Attribute specification
  • id
  • doc
  • contents
  • repeat, repeat-expr, repeat-until
  • if
  • size, size-eos
  • process
  • terminator
  • consume
  • include
  • pad
  • eos-error
• Primitive data types
• Processing specification
  • xor
  • rol
  • ror
  • zlib
• Instance specification
  • pos
  • value

*partially

Additional features:

whence

Can be used togher with pos the define the reference point of the position. Valid values are seek_set, seek_end and seek_cur (default).

Limitations

• No _io (Most uses can be replaced with whence)
• Accessing nested types with :: is not allowed
• No fancy enums
• No nested endianess
• No encoding
• No comparison of string, []byte or custom types
• No min or max functions
• fix type inference
• -2 % 8 = -2
• xor, ror, rol and zlib only work on bytes
• float + int fails

Licenses

The kaitaigo compiler is licensed as GPLv3. The runtime (/runtime) is licensed under MIT license. Everything else is licensed as GPLv3.