mirror of
https://github.com/lightningnetwork/lnd.git
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301 lines
9.0 KiB
Go
301 lines
9.0 KiB
Go
package btcwallet
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import (
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"github.com/btcsuite/btcd/btcec"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/btcsuite/btcd/txscript"
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"github.com/btcsuite/btcd/wire"
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"github.com/btcsuite/btcutil"
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"github.com/btcsuite/btcwallet/waddrmgr"
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"github.com/btcsuite/btcwallet/walletdb"
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"github.com/go-errors/errors"
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"github.com/lightningnetwork/lnd/input"
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"github.com/lightningnetwork/lnd/keychain"
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"github.com/lightningnetwork/lnd/lnwallet"
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)
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// FetchInputInfo queries for the WalletController's knowledge of the passed
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// outpoint. If the base wallet determines this output is under its control,
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// then the original txout should be returned. Otherwise, a non-nil error value
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// of ErrNotMine should be returned instead.
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//
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// This is a part of the WalletController interface.
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func (b *BtcWallet) FetchInputInfo(prevOut *wire.OutPoint) (*lnwallet.Utxo, error) {
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_, txOut, _, confirmations, err := b.wallet.FetchInputInfo(prevOut)
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if err != nil {
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return nil, err
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}
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// Then, we'll populate all of the information required by the struct.
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addressType := lnwallet.UnknownAddressType
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switch {
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case txscript.IsPayToWitnessPubKeyHash(txOut.PkScript):
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addressType = lnwallet.WitnessPubKey
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case txscript.IsPayToScriptHash(txOut.PkScript):
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addressType = lnwallet.NestedWitnessPubKey
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}
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return &lnwallet.Utxo{
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AddressType: addressType,
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Value: btcutil.Amount(txOut.Value),
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PkScript: txOut.PkScript,
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Confirmations: confirmations,
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OutPoint: *prevOut,
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}, nil
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}
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// deriveFromKeyLoc attempts to derive a private key using a fully specified
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// KeyLocator.
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func deriveFromKeyLoc(scopedMgr *waddrmgr.ScopedKeyManager,
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addrmgrNs walletdb.ReadWriteBucket,
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keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {
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path := waddrmgr.DerivationPath{
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InternalAccount: uint32(keyLoc.Family),
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Account: uint32(keyLoc.Family),
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Branch: 0,
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Index: keyLoc.Index,
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}
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addr, err := scopedMgr.DeriveFromKeyPath(addrmgrNs, path)
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if err != nil {
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return nil, err
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}
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return addr.(waddrmgr.ManagedPubKeyAddress).PrivKey()
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}
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// deriveKeyByLocator attempts to derive a key stored in the wallet given a
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// valid key locator.
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func (b *BtcWallet) deriveKeyByLocator(
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keyLoc keychain.KeyLocator) (*btcec.PrivateKey, error) {
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// We'll assume the special lightning key scope in this case.
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scopedMgr, err := b.wallet.Manager.FetchScopedKeyManager(
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b.chainKeyScope,
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)
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if err != nil {
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return nil, err
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}
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// First try to read the key from the cached store, if this fails, then
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// we'll fall through to the method below that requires a database
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// transaction.
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path := waddrmgr.DerivationPath{
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InternalAccount: uint32(keyLoc.Family),
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Account: uint32(keyLoc.Family),
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Branch: 0,
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Index: keyLoc.Index,
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}
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privKey, err := scopedMgr.DeriveFromKeyPathCache(path)
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if err == nil {
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return privKey, nil
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}
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var key *btcec.PrivateKey
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err = walletdb.Update(b.db, func(tx walletdb.ReadWriteTx) error {
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addrmgrNs := tx.ReadWriteBucket(waddrmgrNamespaceKey)
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key, err = deriveFromKeyLoc(scopedMgr, addrmgrNs, keyLoc)
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if waddrmgr.IsError(err, waddrmgr.ErrAccountNotFound) {
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// If we've reached this point, then the account
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// doesn't yet exist, so we'll create it now to ensure
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// we can sign.
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acctErr := scopedMgr.NewRawAccount(
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addrmgrNs, uint32(keyLoc.Family),
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)
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if acctErr != nil {
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return acctErr
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}
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// Now that we know the account exists, we'll attempt
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// to re-derive the private key.
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key, err = deriveFromKeyLoc(
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scopedMgr, addrmgrNs, keyLoc,
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)
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if err != nil {
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return err
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}
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}
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return err
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})
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if err != nil {
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return nil, err
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}
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return key, nil
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}
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// fetchPrivKey attempts to retrieve the raw private key corresponding to the
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// passed public key if populated, or the key descriptor path (if non-empty).
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func (b *BtcWallet) fetchPrivKey(
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keyDesc *keychain.KeyDescriptor) (*btcec.PrivateKey, error) {
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// If the key locator within the descriptor *isn't* empty, then we can
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// directly derive the keys raw.
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emptyLocator := keyDesc.KeyLocator.IsEmpty()
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if !emptyLocator || keyDesc.PubKey == nil {
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return b.deriveKeyByLocator(keyDesc.KeyLocator)
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}
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hash160 := btcutil.Hash160(keyDesc.PubKey.SerializeCompressed())
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addr, err := btcutil.NewAddressWitnessPubKeyHash(hash160, b.netParams)
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if err != nil {
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return nil, err
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}
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// Otherwise, we'll attempt to derive the key based on the address.
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// This will only work if we've already derived this address in the
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// past, since the wallet relies on a mapping of addr -> key.
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key, err := b.wallet.PrivKeyForAddress(addr)
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switch {
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// If we didn't find this key in the wallet, then there's a chance that
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// this is actually an "empty" key locator. The legacy KeyLocator
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// format failed to properly distinguish an empty key locator from the
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// very first in the index (0, 0).IsEmpty() == true.
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case waddrmgr.IsError(err, waddrmgr.ErrAddressNotFound) && emptyLocator:
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return b.deriveKeyByLocator(keyDesc.KeyLocator)
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case err != nil:
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return nil, err
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default:
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return key, nil
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}
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}
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// maybeTweakPrivKey examines the single and double tweak parameters on the
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// passed sign descriptor and may perform a mapping on the passed private key
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// in order to utilize the tweaks, if populated.
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func maybeTweakPrivKey(signDesc *input.SignDescriptor,
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privKey *btcec.PrivateKey) (*btcec.PrivateKey, error) {
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var retPriv *btcec.PrivateKey
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switch {
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case signDesc.SingleTweak != nil:
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retPriv = input.TweakPrivKey(privKey,
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signDesc.SingleTweak)
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case signDesc.DoubleTweak != nil:
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retPriv = input.DeriveRevocationPrivKey(privKey,
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signDesc.DoubleTweak)
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default:
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retPriv = privKey
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}
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return retPriv, nil
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}
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// SignOutputRaw generates a signature for the passed transaction according to
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// the data within the passed SignDescriptor.
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//
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// This is a part of the WalletController interface.
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func (b *BtcWallet) SignOutputRaw(tx *wire.MsgTx,
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signDesc *input.SignDescriptor) (input.Signature, error) {
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witnessScript := signDesc.WitnessScript
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// First attempt to fetch the private key which corresponds to the
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// specified public key.
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privKey, err := b.fetchPrivKey(&signDesc.KeyDesc)
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if err != nil {
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return nil, err
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}
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// If a tweak (single or double) is specified, then we'll need to use
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// this tweak to derive the final private key to be used for signing
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// this output.
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privKey, err = maybeTweakPrivKey(signDesc, privKey)
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if err != nil {
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return nil, err
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}
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// TODO(roasbeef): generate sighash midstate if not present?
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amt := signDesc.Output.Value
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sig, err := txscript.RawTxInWitnessSignature(
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tx, signDesc.SigHashes, signDesc.InputIndex, amt,
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witnessScript, signDesc.HashType, privKey,
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)
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if err != nil {
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return nil, err
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}
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// Chop off the sighash flag at the end of the signature.
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return btcec.ParseDERSignature(sig[:len(sig)-1], btcec.S256())
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}
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// ComputeInputScript generates a complete InputScript for the passed
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// transaction with the signature as defined within the passed SignDescriptor.
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// This method is capable of generating the proper input script for both
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// regular p2wkh output and p2wkh outputs nested within a regular p2sh output.
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//
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// This is a part of the WalletController interface.
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func (b *BtcWallet) ComputeInputScript(tx *wire.MsgTx,
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signDesc *input.SignDescriptor) (*input.Script, error) {
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// If a tweak (single or double) is specified, then we'll need to use
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// this tweak to derive the final private key to be used for signing
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// this output.
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privKeyTweaker := func(k *btcec.PrivateKey) (*btcec.PrivateKey, error) {
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return maybeTweakPrivKey(signDesc, k)
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}
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// Let the wallet compute the input script now.
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witness, sigScript, err := b.wallet.ComputeInputScript(
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tx, signDesc.Output, signDesc.InputIndex, signDesc.SigHashes,
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signDesc.HashType, privKeyTweaker,
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)
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if err != nil {
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return nil, err
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}
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return &input.Script{
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Witness: witness,
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SigScript: sigScript,
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}, nil
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}
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// A compile time check to ensure that BtcWallet implements the Signer
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// interface.
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var _ input.Signer = (*BtcWallet)(nil)
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// SignMessage attempts to sign a target message with the private key that
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// corresponds to the passed key locator. If the target private key is unable to
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// be found, then an error will be returned. The actual digest signed is the
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// double SHA-256 of the passed message.
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//
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// NOTE: This is a part of the MessageSigner interface.
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func (b *BtcWallet) SignMessage(keyLoc keychain.KeyLocator,
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msg []byte, doubleHash bool) (*btcec.Signature, error) {
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// First attempt to fetch the private key which corresponds to the
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// specified public key.
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privKey, err := b.fetchPrivKey(&keychain.KeyDescriptor{
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KeyLocator: keyLoc,
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})
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if err != nil {
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return nil, err
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}
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// Double hash and sign the data.
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var msgDigest []byte
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if doubleHash {
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msgDigest = chainhash.DoubleHashB(msg)
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} else {
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msgDigest = chainhash.HashB(msg)
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}
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sign, err := privKey.Sign(msgDigest)
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if err != nil {
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return nil, errors.Errorf("unable sign the message: %v", err)
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}
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return sign, nil
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}
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// A compile time check to ensure that BtcWallet implements the MessageSigner
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// interface.
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var _ lnwallet.MessageSigner = (*BtcWallet)(nil)
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