waddrmgr: extract script hash into identity closure

As a preparation for when the identifier of a script isn't the hash of a
script in every case anymore, we extract that part out of the
importScriptAddress method and rename it.
Pay-to-Taproot script addresses use the x-only coordinates of a tweaked
public key as the address identifier.

waddrmgr/scoped_manager.go

@@ -129,6 +129,24 @@ func (k KeyScope) String() string {
 	return fmt.Sprintf("m/%v'/%v'", k.Purpose, k.Coin)
 }
 
+// Identity is a closure that returns the identifier of an address.
+type Identity func() []byte
+
+// ScriptHashIdentity returns the identity closure for a p2sh script.
+func ScriptHashIdentity(script []byte) Identity {
+	return func() []byte {
+		return btcutil.Hash160(script)
+	}
+}
+
+// WitnessScriptHashIdentity returns the identity closure for a p2wsh script.
+func WitnessScriptHashIdentity(script []byte) Identity {
+	return func() []byte {
+		digest := sha256.Sum256(script)
+		return digest[:]
+	}
+}
+
 // ScopeAddrSchema is the address schema of a particular KeyScope. This will be
 // persisted within the database, and will be consulted when deriving any keys
 // for a particular scope to know how to encode the public keys as addresses.
@@ -2065,7 +2083,9 @@ func (s *ScopedKeyManager) toImportedPublicManagedAddress(
 func (s *ScopedKeyManager) ImportScript(ns walletdb.ReadWriteBucket,
 	script []byte, bs *BlockStamp) (ManagedScriptAddress, error) {
 
-	return s.importScriptAddress(ns, script, bs, Script, 0, true)
+	return s.importScriptAddress(
+		ns, ScriptHashIdentity(script), script, bs, Script, 0, true,
+	)
 }
 
 // ImportWitnessScript imports a user-provided script into the address manager.
@@ -2085,14 +2105,15 @@ func (s *ScopedKeyManager) ImportWitnessScript(ns walletdb.ReadWriteBucket,
 	isSecretScript bool) (ManagedScriptAddress, error) {
 
 	return s.importScriptAddress(
-		ns, script, bs, WitnessScript, witnessVersion, isSecretScript,
+		ns, WitnessScriptHashIdentity(script), script, bs,
+		WitnessScript, witnessVersion, isSecretScript,
 	)
 }
 
 // importScriptAddress imports a new pay-to-script or pay-to-witness-script
 // address.
 func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
-	script []byte, bs *BlockStamp, addrType AddressType,
+	identity Identity, script []byte, bs *BlockStamp, addrType AddressType,
 	witnessVersion byte, isSecretScript bool) (ManagedScriptAddress,
 	error) {
 
@@ -2111,30 +2132,21 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 		return nil, managerError(ErrWatchingOnly, errWatchingOnly, nil)
 	}
 
-	// Witness script addresses use a SHA256.
-	var scriptHash []byte
-	switch addrType {
-	case WitnessScript:
-		digest := sha256.Sum256(script)
-		scriptHash = digest[:]
-	default:
-		scriptHash = btcutil.Hash160(script)
-	}
-
 	// Prevent duplicates.
-	alreadyExists := s.existsAddress(ns, scriptHash)
+	scriptIdent := identity()
+	alreadyExists := s.existsAddress(ns, scriptIdent)
 	if alreadyExists {
-		str := fmt.Sprintf("address for script hash %x already exists",
-			scriptHash)
+		str := fmt.Sprintf("address for script hash/key %x already "+
+			"exists", scriptIdent)
 		return nil, managerError(ErrDuplicateAddress, str, nil)
 	}
 
-	// Encrypt the script hash using the crypto public key so it is
+	// Encrypt the script hash/key using the crypto public key, so it is
 	// accessible when the address manager is locked or watching-only.
-	encryptedHash, err := s.rootManager.cryptoKeyPub.Encrypt(scriptHash)
+	encryptedHash, err := s.rootManager.cryptoKeyPub.Encrypt(scriptIdent)
 	if err != nil {
-		str := fmt.Sprintf("failed to encrypt script hash %x",
-			scriptHash)
+		str := fmt.Sprintf("failed to encrypt script hash/key %x",
+			scriptIdent)
 		return nil, managerError(ErrCrypto, str, err)
 	}
 
@@ -2151,7 +2163,7 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 	encryptedScript, err := cryptoKey.Encrypt(script)
 	if err != nil {
 		str := fmt.Sprintf("failed to encrypt script for %x",
-			scriptHash)
+			scriptIdent)
 		return nil, managerError(ErrCrypto, str, err)
 	}
 
@@ -2169,14 +2181,14 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 	switch addrType {
 	case WitnessScript:
 		err = putWitnessScriptAddress(
-			ns, &s.scope, scriptHash, ImportedAddrAccount, ssNone,
+			ns, &s.scope, scriptIdent, ImportedAddrAccount, ssNone,
 			witnessVersion, isSecretScript, encryptedHash,
 			encryptedScript,
 		)
 
 	default:
 		err = putScriptAddress(
-			ns, &s.scope, scriptHash, ImportedAddrAccount, ssNone,
+			ns, &s.scope, scriptIdent, ImportedAddrAccount, ssNone,
 			encryptedHash, encryptedScript,
 		)
 	}
@@ -2210,7 +2222,7 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 	switch addrType {
 	case WitnessScript:
 		witnessAddr, err := newWitnessScriptAddress(
-			s, ImportedAddrAccount, scriptHash, encryptedScript,
+			s, ImportedAddrAccount, scriptIdent, encryptedScript,
 			witnessVersion, isSecretScript,
 		)
 		if err != nil {
@@ -2221,7 +2233,7 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 
 	default:
 		scriptAddr, err := newScriptAddress(
-			s, ImportedAddrAccount, scriptHash, encryptedScript,
+			s, ImportedAddrAccount, scriptIdent, encryptedScript,
 		)
 		if err != nil {
 			return nil, err
@@ -2238,7 +2250,7 @@ func (s *ScopedKeyManager) importScriptAddress(ns walletdb.ReadWriteBucket,
 
 	// Add the new managed address to the cache of recent addresses and
 	// return it.
-	s.addrs[addrKey(scriptHash)] = managedAddr
+	s.addrs[addrKey(scriptIdent)] = managedAddr
 	return managedAddr, nil
 }