leslie-wang/go-xdr

Implements the XDR standard as specified in RFC 4506 in pure Google Go (Golang)

go-xdr

[] (https://travis-ci.org/davecgh/go-xdr) [![Coverage Status] (https://coveralls.io/repos/davecgh/go-xdr/badge.png?branch=master)] (https://coveralls.io/r/davecgh/go-xdr?branch=master)

Go-xdr implements the data representation portion of the External Data Representation (XDR) standard protocol as specified in RFC 4506 (obsoletes RFC 1832 and RFC 1014) in Pure Go (Golang). A comprehensive suite of tests are provided to ensure proper functionality. It is licensed under the liberal ISC license, so it may be used in open source or commercial projects.

NOTE: Version 1 of this package is still available via the github.com/davecgh/go-xdr/xdr import path to avoid breaking existing clients. However, it is highly recommended that all old clients upgrade to version 2 and all new clients use version 2. In addition to some speed optimizations, version 2 has been been updated to work with standard the io.Reader and io.Writer interfaces instead of raw byte slices. This allows it to be much more flexible and work directly with files, network connections, etc.

Documentation

[] (http://godoc.org/github.com/davecgh/go-xdr/xdr2)

Full go doc style documentation for the project can be viewed online without installing this package by using the excellent GoDoc site here: http://godoc.org/github.com/davecgh/go-xdr/xdr2

You can also view the documentation locally once the package is installed with the godoc tool by running godoc -http=":6060" and pointing your browser to http://localhost:6060/pkg/github.com/davecgh/go-xdr/xdr2/

Installation

$ go get github.com/davecgh/go-xdr/xdr2

Sample Decode Program

package main

import (
	"bytes"
    "fmt"

    "github.com/davecgh/go-xdr/xdr2"
)

func main() {
	// Hypothetical image header format.
	type ImageHeader struct {
		Signature   [3]byte
		Version     uint32
		IsGrayscale bool
		NumSections uint32
	}

	// XDR encoded data described by the above structure.  Typically this would
	// be read from a file or across the network, but use a manual byte array
	// here as an example.
	encodedData := []byte{
		0xAB, 0xCD, 0xEF, 0x00, // Signature
		0x00, 0x00, 0x00, 0x02, // Version
		0x00, 0x00, 0x00, 0x01, // IsGrayscale
		0x00, 0x00, 0x00, 0x0A, // NumSections
	}

	// Declare a variable to provide Unmarshal with a concrete type and instance
	// to decode into.
	var h ImageHeader
	bytesRead, err := xdr.Unmarshal(bytes.NewReader(encodedData), &h)
	if err != nil {
		fmt.Println(err)
		return
	}
  
	fmt.Println("bytes read:", bytesRead)
	fmt.Printf("h: %+v", h)
}

The struct instance, h, will then contain the following values:

h.Signature = [3]byte{0xAB, 0xCD, 0xEF}
h.Version = 2
h.IsGrayscale = true
h.NumSections = 10

Sample Encode Program

package main

import (
	"bytes"
    "fmt"

    "github.com/davecgh/go-xdr/xdr2"
)

func main() {
	// Hypothetical image header format.
	type ImageHeader struct {
		Signature   [3]byte
		Version     uint32
		IsGrayscale bool
		NumSections uint32
	}

	// Sample image header data.
	h := ImageHeader{[3]byte{0xAB, 0xCD, 0xEF}, 2, true, 10}

	// Use marshal to automatically determine the appropriate underlying XDR
	// types and encode.
	var w bytes.Buffer
	bytesWritten, err := xdr.Marshal(&w, &h)
	if err != nil {
		fmt.Println(err)
		return
	}

	encodedData := w.Bytes()
	fmt.Println("bytes written:", bytesWritten)
	fmt.Println("encoded data:", encodedData)
}

The result, encodedData, will then contain the following XDR encoded byte sequence:

0xAB, 0xCD, 0xEF, 0x00,
0x00, 0x00, 0x00, 0x02,
0x00, 0x00, 0x00, 0x01,
0x00, 0x00, 0x00, 0x0A,

License

Go-xdr is licensed under the liberal ISC License.