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// Copyright (C) 2019-2023 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package basics
import (
"bytes"
"encoding/base32"
"fmt"
"github.com/algorand/go-algorand/crypto"
)
type (
// Address is a unique identifier corresponding to ownership of money
Address crypto.Digest
)
const (
checksumLength = 4
)
var base32Encoder = base32.StdEncoding.WithPadding(base32.NoPadding)
// GetChecksum returns the checksum as []byte
// Checksum in Algorand are the last 4 bytes of the shortAddress Hash. H(Address)[28:]
func (addr Address) GetChecksum() []byte {
shortAddressHash := crypto.Hash(addr[:])
checksum := shortAddressHash[len(shortAddressHash)-checksumLength:]
return checksum
}
// GetUserAddress returns the human-readable, checksummed version of the address
func (addr Address) GetUserAddress() string {
return addr.String()
}
// UnmarshalChecksumAddress tries to unmarshal the checksummed address string.
// Algorand strings addresses ( base32 encoded ) have a postamble which serves as the checksum of the address.
// When converted to an Address object representation, that checksum is dropped (after validation).
func UnmarshalChecksumAddress(address string) (Address, error) {
decoded, err := base32Encoder.DecodeString(address)
if err != nil {
return Address{}, fmt.Errorf("failed to decode address %s to base 32", address)
}
var short Address
if len(decoded) < len(short) {
return Address{}, fmt.Errorf("decoded bad addr: %s", address)
}
copy(short[:], decoded[:len(short)])
incomingchecksum := decoded[len(decoded)-checksumLength:]
calculatedchecksum := short.GetChecksum()
isValid := bytes.Equal(incomingchecksum, calculatedchecksum)
if !isValid {
return Address{}, fmt.Errorf("address %s is malformed, checksum verification failed", address)
}
// Validate that we had a canonical string representation
if short.String() != address {
return Address{}, fmt.Errorf("address %s is non-canonical", address)
}
return short, nil
}
// String returns a string representation of Address
func (addr Address) String() string {
addrWithChecksum := make([]byte, crypto.DigestSize+checksumLength)
copy(addrWithChecksum[:crypto.DigestSize], addr[:])
// calling addr.GetChecksum() here takes 20ns more than just rolling it out, so we'll just repeat that code.
shortAddressHash := crypto.Hash(addr[:])
copy(addrWithChecksum[crypto.DigestSize:], shortAddressHash[len(shortAddressHash)-checksumLength:])
return base32Encoder.EncodeToString(addrWithChecksum)
}
// MarshalText returns the address string as an array of bytes
func (addr Address) MarshalText() ([]byte, error) {
return []byte(addr.String()), nil
}
// UnmarshalText initializes the Address from an array of bytes.
func (addr *Address) UnmarshalText(text []byte) error {
address, err := UnmarshalChecksumAddress(string(text))
if err == nil {
*addr = address
return nil
}
return err
}
// IsZero checks if an address is the zero value.
func (addr Address) IsZero() bool {
return addr == Address{}
}
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