lnd.xprv/lnwallet/btcwallet/blockchain.go
Olaoluwa Osuntokun af4afdb6f0
lnwallet: use btcutil.NewAmount for BTC -> SAT conversions
In this commit, we fix an existing rounding related bug in the codebase.
The RPC interface for btcd and bitcoind return values in BTC rather than
in satoshis. So in several places, we're forced to convert ourselves
manually. The existing logic attempted to do this, but didn't properly
account for rounding. As a result, our values can be off due to not
rounding incorrectly.

The fix for this is easy: simply properly use btcutil.NewAmount
everywhere which does rounding properly.

Fixes #939.
2018-03-25 19:15:18 -07:00

141 lines
3.6 KiB
Go

package btcwallet
import (
"encoding/hex"
"errors"
"fmt"
"github.com/roasbeef/btcd/chaincfg/chainhash"
"github.com/roasbeef/btcd/wire"
"github.com/roasbeef/btcutil"
"github.com/lightninglabs/neutrino"
"github.com/lightningnetwork/lnd/lnwallet"
"github.com/roasbeef/btcwallet/chain"
"github.com/roasbeef/btcwallet/waddrmgr"
)
var (
// ErrOutputSpent is returned by the GetUtxo method if the target output
// for lookup has already been spent.
ErrOutputSpent = errors.New("target output has been spent")
// ErrOutputNotFound signals that the desired output could not be
// located.
ErrOutputNotFound = errors.New("target output was not found")
)
// GetBestBlock returns the current height and hash of the best known block
// within the main chain.
//
// This method is a part of the lnwallet.BlockChainIO interface.
func (b *BtcWallet) GetBestBlock() (*chainhash.Hash, int32, error) {
return b.chain.GetBestBlock()
}
// GetUtxo returns the original output referenced by the passed outpoint.
//
// This method is a part of the lnwallet.BlockChainIO interface.
func (b *BtcWallet) GetUtxo(op *wire.OutPoint, heightHint uint32) (*wire.TxOut, error) {
switch backend := b.chain.(type) {
case *chain.NeutrinoClient:
spendReport, err := backend.CS.GetUtxo(
neutrino.WatchOutPoints(*op),
neutrino.StartBlock(&waddrmgr.BlockStamp{
Height: int32(heightHint),
}),
)
if err != nil {
return nil, err
}
// If the spend report is nil, then the output was not found in
// the rescan.
if spendReport == nil {
return nil, ErrOutputNotFound
}
// If the spending transaction is populated in the spend report,
// this signals that the output has already been spent.
if spendReport.SpendingTx != nil {
return nil, ErrOutputSpent
}
// Otherwise, the output is assumed to be in the UTXO.
return spendReport.Output, nil
case *chain.RPCClient:
txout, err := backend.GetTxOut(&op.Hash, op.Index, false)
if err != nil {
return nil, err
} else if txout == nil {
return nil, ErrOutputSpent
}
pkScript, err := hex.DecodeString(txout.ScriptPubKey.Hex)
if err != nil {
return nil, err
}
// We'll ensure we properly convert the amount given in BTC to
// satoshis.
amt, err := btcutil.NewAmount(txout.Value)
if err != nil {
return nil, err
}
return &wire.TxOut{
Value: int64(amt),
PkScript: pkScript,
}, nil
case *chain.BitcoindClient:
txout, err := backend.GetTxOut(&op.Hash, op.Index, false)
if err != nil {
return nil, err
} else if txout == nil {
return nil, ErrOutputSpent
}
pkScript, err := hex.DecodeString(txout.ScriptPubKey.Hex)
if err != nil {
return nil, err
}
// Sadly, gettxout returns the output value in BTC instead of
// satoshis.
amt, err := btcutil.NewAmount(txout.Value)
if err != nil {
return nil, err
}
return &wire.TxOut{
Value: int64(amt),
PkScript: pkScript,
}, nil
default:
return nil, fmt.Errorf("unknown backend")
}
}
// GetBlock returns a raw block from the server given its hash.
//
// This method is a part of the lnwallet.BlockChainIO interface.
func (b *BtcWallet) GetBlock(blockHash *chainhash.Hash) (*wire.MsgBlock, error) {
return b.chain.GetBlock(blockHash)
}
// GetBlockHash returns the hash of the block in the best blockchain at the
// given height.
//
// This method is a part of the lnwallet.BlockChainIO interface.
func (b *BtcWallet) GetBlockHash(blockHeight int64) (*chainhash.Hash, error) {
return b.chain.GetBlockHash(blockHeight)
}
// A compile time check to ensure that BtcWallet implements the BlockChainIO
// interface.
var _ lnwallet.WalletController = (*BtcWallet)(nil)