uri.go

package otp

import (
	"crypto/md5"
	"crypto/sha1"
	"crypto/sha256"
	"crypto/sha512"
	"errors"
	"net/url"
	"strconv"
	"strings"
)

// ToURI returns the string representation of the Key.
func (k Key) ToURI() string {

	uri := url.URL{
		Scheme: "otpauth",
		Host:   k.Method,
		Path:   "/" + k.Label,
	}

	params := url.Values{}
	params.Set("secret", k.Secret32)
	if k.Issuer != "" {
		params.Set("issuer", k.Issuer)
	}

	hashName := strings.Split(
		strings.Split(getFuncName(k.Algo), ".")[0], "/")[1]
	params.Set("algo", hashName)

	params.Set("digits", strconv.Itoa(k.Digits))

	if k.Method == "totp" {
		params.Set("period", strconv.Itoa(k.Period))
	} else {
		params.Set("counter", strconv.Itoa(k.Counter))
	}

	uri.RawQuery = params.Encode()

	return uri.String()
}

// FromURI parses an otpauth URI into the key.
// Defaults are included for the hashing algorithm (sha1.New), digits (6), and period (30); these parameters may be excluded from the URI. The issuer is optional. For totp, only the method, label, and secret are required. See https://code.google.com/p/google-authenticator/wiki/KeyUriFormat for more information.
//
// Example:
//      k.FromURI("otpauth://totp/Example:alice@google.com?algo=sha1&digits=6&issuer=Example&period=30&secret=NAR5XTDD3EQU22YU")
func (k *Key) FromURI(uri string) error {

	u, err := url.ParseRequestURI(uri)
	if err != nil {
		return err
	}

	if strings.ToLower(u.Scheme) != "otpauth" {
		return errors.New("invalid scheme")
	}

	(*k).Method = strings.ToLower(u.Host)

	if len(u.Path) < 2 {
		return errors.New("missing label")
	}
	(*k).Label = u.Path[1:len(u.Path)]

	params := u.Query()
	(*k).Secret32 = strings.ToUpper(params.Get("secret"))
	(*k).Issuer = params.Get("issuer")

	switch strings.ToUpper(params.Get("algo")) {
	case "SHA256":
		(*k).Algo = sha256.New
	case "SHA512":
		(*k).Algo = sha512.New
	case "MD5":
		(*k).Algo = md5.New
	default:
		(*k).Algo = sha1.New
	}

	digits := params.Get("digits")
	if digits != "" {
		d, err := strconv.Atoi(digits)
		if err != nil {
			return errors.New("digits is non-integer")
		}
		(*k).Digits = d
	} else {
		(*k).Digits = 6
	}

	if u.Host == "totp" {
		period := params.Get("period")
		if period != "" {
			p, err := strconv.Atoi(period)
			if err != nil {
				return errors.New("period is non-integer")
			}
			(*k).Period = p
		} else {
			(*k).Period = 30
		}
	} else if u.Host == "hotp" {
		counter := params.Get("counter")
		if counter != "" {
			c, err := strconv.Atoi(counter)
			if err != nil {
				return errors.New("counter is non-integer")
			}
			(*k).Counter = c
		}
	}

	return nil
}