multicodec

README

go-multicodec

Go utility library to provide encoding and decoding of multicodec values.

Table of Contents

• Install
• Usage
• Maintainers
• Contribute
• License

Install

go-multicodec is a standard Go module which can be installed with:

go get github.com/pulsedomains/go-multicodec

Usage

Example

import (
    "bytes"
    "encoding/hex"
    "errors"

    multicodec "github.com/pulsedomains/go-multicodec"
)

func main() {
    // Data in this case is an IPFS hash in multihash format with a dag-pb content type
    data, err := hex.DecodeString("70122029f2d17be6139079dc48696d1f582a8530eb9805b561eda517e22a892c7e3f1f")
    if err != nil {
        panic(err)
    }

    // Add the "ipfs-ns" namespace codec
    dataWithCodec, err := multicodec.AddCodec("ipfs-ns", data)
    if err != nil {
        panic(err)
    }

    if !multicodec.IsCodec("ipfs-ns", dataWithCodec) {
        panic(errors.New("data does not have correct codec prefix"))
    }

    // Remove the codec
    dataWithoutCodec, _, err := multicodec.RemoveCodec(dataWithCodec)
    if err != nil {
        panic(err)
    }

    if !bytes.Equal(data, dataWithoutCodec) {
        panic(errors.New("data mismatch"))
    }
}

Maintainers

Jim McDonald: @mcdee.

Contribute

Contributions welcome. Please check out the issues.

License

Apache-2.0 © 2019 Weald Technology Trading Ltd

Documentation

Overview

Package multicodec provides the ability to add and remove codec prefixes from data.

Index

• func AddCodec(name string, data []byte) ([]byte, error)
• func GetCodec(data []byte) (uint64, error)
• func ID(name string) (uint64, error)
• func IsCodec(name string, data []byte) bool
• func MustID(name string) uint64
• func MustName(id uint64) string
• func Name(id uint64) (string, error)
• func RemoveCodec(data []byte) ([]byte, uint64, error)

Functions

func AddCodec

func AddCodec(name string, data []byte) ([]byte, error)

AddCodec adds a codec prefix to a byte array. It returns a new byte array with the relevant codec prefixed.

func GetCodec

func GetCodec(data []byte) (uint64, error)

GetCodec returns the ID of the codec prefix from a byte array

func ID

func ID(name string) (uint64, error)

ID obtains the ID of a codec from its name

func IsCodec

func IsCodec(name string, data []byte) bool

IsCodec returns true if the data is of the supplied codec prefix, otherwise false

func MustID

func MustID(name string) uint64

MustID obtains the ID of a codec from its name, panicking if not present.

func MustName

func MustName(id uint64) string

MustName obtains the name of a codec from its ID, panicking if not present.

func Name

func Name(id uint64) (string, error)

Name obtains the name of a codec from its ID

func RemoveCodec

func RemoveCodec(data []byte) ([]byte, uint64, error)

RemoveCodec removes a codec prefix from a byte array. It returns a slice of the input byte array without the codec prefix, along with the ID of the codec that has been removed.