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zpay32: add distinct hrp to invoice

The Core devs decided to us the same bech32 HRP for Signet as is used
for the current Testnet3. This might be okay for on-chain addresses
since they are compatible in theory. But for invoices we want to use a
distinct HRP to distinguish testnet from signet.
Also see spec PR
https://github.com/lightningnetwork/lightning-rfc/pull/844 for more
information about the reasoning.
master
Oliver Gugger 3 years ago
parent
commit
044e1e692f
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GPG Key ID: 8E4256593F177720
  1. 17
      zpay32/decode.go
  2. 11
      zpay32/encode.go

17
zpay32/decode.go

@ -45,8 +45,17 @@ func Decode(invoice string, net *chaincfg.Params) (*Invoice, error) {
}
// The next characters should be a valid prefix for a segwit BIP173
// address that match the active network.
if !strings.HasPrefix(hrp[2:], net.Bech32HRPSegwit) {
// address that match the active network except for signet where we add
// an additional "s" to differentiate it from the older testnet3 (Core
// devs decided to use the same hrp for signet as for testnet3 which is
// not optimal for LN). See
// https://github.com/lightningnetwork/lightning-rfc/pull/844 for more
// information.
expectedPrefix := net.Bech32HRPSegwit
if net.Name == chaincfg.SigNetParams.Name {
expectedPrefix = "tbs"
}
if !strings.HasPrefix(hrp[2:], expectedPrefix) {
return nil, fmt.Errorf(
"invoice not for current active network '%s'", net.Name)
}
@ -54,7 +63,7 @@ func Decode(invoice string, net *chaincfg.Params) (*Invoice, error) {
// Optionally, if there's anything left of the HRP after ln + the segwit
// prefix, we try to decode this as the payment amount.
var netPrefixLength = len(net.Bech32HRPSegwit) + 2
var netPrefixLength = len(expectedPrefix) + 2
if len(hrp) > netPrefixLength {
amount, err := decodeAmount(hrp[netPrefixLength:])
if err != nil {
@ -378,7 +387,7 @@ func parseMinFinalCLTVExpiry(data []byte) (*uint64, error) {
// parseFallbackAddr converts the data (encoded in base32) into a fallback
// on-chain address.
func parseFallbackAddr(data []byte, net *chaincfg.Params) (btcutil.Address, error) {
func parseFallbackAddr(data []byte, net *chaincfg.Params) (btcutil.Address, error) { // nolint:dupl
// Checks if the data is empty or contains a version without an address.
if len(data) < 2 {
return nil, fmt.Errorf("empty fallback address field")

11
zpay32/encode.go

@ -5,6 +5,7 @@ import (
"encoding/binary"
"fmt"
"github.com/btcsuite/btcd/chaincfg"
"github.com/btcsuite/btcd/chaincfg/chainhash"
"github.com/btcsuite/btcutil"
"github.com/btcsuite/btcutil/bech32"
@ -51,8 +52,16 @@ func (invoice *Invoice) Encode(signer MessageSigner) (string, error) {
return "", err
}
// The human-readable part (hrp) is "ln" + net hrp + optional amount.
// The human-readable part (hrp) is "ln" + net hrp + optional amount,
// except for signet where we add an additional "s" to differentiate it
// from the older testnet3 (Core devs decided to use the same hrp for
// signet as for testnet3 which is not optimal for LN). See
// https://github.com/lightningnetwork/lightning-rfc/pull/844 for more
// information.
hrp := "ln" + invoice.Net.Bech32HRPSegwit
if invoice.Net.Name == chaincfg.SigNetParams.Name {
hrp = "lntbs"
}
if invoice.MilliSat != nil {
// Encode the amount using the fewest possible characters.
am, err := encodeAmount(*invoice.MilliSat)

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