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// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
// Spec at https://github.com/ethereum/wiki/wiki/ICAP:-Inter-exchange-Client-Address-Protocol
package common
import (
"errors"
"math/big"
"strconv"
"strings"
)
var (
Base36Chars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"
ICAPLengthError = errors.New("Invalid ICAP length")
ICAPEncodingError = errors.New("Invalid ICAP encoding")
ICAPChecksumError = errors.New("Invalid ICAP checksum")
ICAPCountryCodeError = errors.New("Invalid ICAP country code")
ICAPAssetIdentError = errors.New("Invalid ICAP asset identifier")
ICAPInstCodeError = errors.New("Invalid ICAP institution code")
ICAPClientIdentError = errors.New("Invalid ICAP client identifier")
)
func ICAPToAddress(s string) (Address, error) {
switch len(s) {
case 35: // "XE" + 2 digit checksum + 31 base-36 chars of address
return parseICAP(s)
case 34: // "XE" + 2 digit checksum + 30 base-36 chars of address
return parseICAP(s)
case 20: // "XE" + 2 digit checksum + 3-char asset identifier +
// 4-char institution identifier + 9-char institution client identifier
return parseIndirectICAP(s)
default:
return Address{}, ICAPLengthError
}
}
func parseICAP(s string) (Address, error) {
if !strings.HasPrefix(s, "XE") {
return Address{}, ICAPCountryCodeError
}
if err := validCheckSum(s); err != nil {
return Address{}, err
}
// checksum is ISO13616, Ethereum address is base-36
bigAddr, _ := new(big.Int).SetString(s[4:], 36)
return BigToAddress(bigAddr), nil
}
func parseIndirectICAP(s string) (Address, error) {
if !strings.HasPrefix(s, "XE") {
return Address{}, ICAPCountryCodeError
}
if s[4:7] != "ETH" {
return Address{}, ICAPAssetIdentError
}
if err := validCheckSum(s); err != nil {
return Address{}, err
}
// TODO: integrate with ICAP namereg
return Address{}, errors.New("not implemented")
}
func AddressToICAP(a Address) (string, error) {
enc := base36Encode(a.Big())
// zero padd encoded address to Direct ICAP length if needed
if len(enc) < 30 {
enc = join(strings.Repeat("0", 30-len(enc)), enc)
}
icap := join("XE", checkDigits(enc), enc)
return icap, nil
}
// TODO: integrate with ICAP namereg when it's available
func AddressToIndirectICAP(a Address, instCode string) (string, error) {
// return addressToIndirectICAP(a, instCode)
return "", errors.New("not implemented")
}
func addressToIndirectICAP(a Address, instCode string) (string, error) {
// TODO: add addressToClientIdent which grabs client ident from ICAP namereg
//clientIdent := addressToClientIdent(a)
clientIdent := "todo"
return clientIdentToIndirectICAP(instCode, clientIdent)
}
func clientIdentToIndirectICAP(instCode, clientIdent string) (string, error) {
if len(instCode) != 4 || !validBase36(instCode) {
return "", ICAPInstCodeError
}
if len(clientIdent) != 9 || !validBase36(instCode) {
return "", ICAPClientIdentError
}
// currently ETH is only valid asset identifier
s := join("ETH", instCode, clientIdent)
return join("XE", checkDigits(s), s), nil
}
// https://en.wikipedia.org/wiki/International_Bank_Account_Number#Validating_the_IBAN
func validCheckSum(s string) error {
s = join(s[4:], s[:4])
expanded, err := iso13616Expand(s)
if err != nil {
return err
}
checkSumNum, _ := new(big.Int).SetString(expanded, 10)
if checkSumNum.Mod(checkSumNum, Big97).Cmp(Big1) != 0 {
return ICAPChecksumError
}
return nil
}
func checkDigits(s string) string {
expanded, _ := iso13616Expand(strings.Join([]string{s, "XE00"}, ""))
num, _ := new(big.Int).SetString(expanded, 10)
num.Sub(Big98, num.Mod(num, Big97))
checkDigits := num.String()
// zero padd checksum
if len(checkDigits) == 1 {
checkDigits = join("0", checkDigits)
}
return checkDigits
}
// not base-36, but expansion to decimal literal: A = 10, B = 11, ... Z = 35
func iso13616Expand(s string) (string, error) {
var parts []string
if !validBase36(s) {
return "", ICAPEncodingError
}
for _, c := range s {
i := uint64(c)
if i >= 65 {
parts = append(parts, strconv.FormatUint(uint64(c)-55, 10))
} else {
parts = append(parts, string(c))
}
}
return join(parts...), nil
}
func base36Encode(i *big.Int) string {
var chars []rune
x := new(big.Int)
for {
x.Mod(i, Big36)
chars = append(chars, rune(Base36Chars[x.Uint64()]))
i.Div(i, Big36)
if i.Cmp(Big0) == 0 {
break
}
}
// reverse slice
for i, j := 0, len(chars)-1; i < j; i, j = i+1, j-1 {
chars[i], chars[j] = chars[j], chars[i]
}
return string(chars)
}
func validBase36(s string) bool {
for _, c := range s {
i := uint64(c)
// 0-9 or A-Z
if i < 48 || (i > 57 && i < 65) || i > 90 {
return false
}
}
return true
}
func join(s ...string) string {
return strings.Join(s, "")
}
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