Merge pull request #7464 from guggero/script-builder-capacity

input: reduce memory allocation for ScriptBuilder

channeldb/graph.go

@@ -22,6 +22,7 @@ import (
 	"github.com/btcsuite/btcd/wire"
 	"github.com/lightningnetwork/lnd/aliasmgr"
 	"github.com/lightningnetwork/lnd/batch"
+	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/kvdb"
 	"github.com/lightningnetwork/lnd/lnwire"
 	"github.com/lightningnetwork/lnd/routing/route"
@@ -3731,35 +3732,17 @@ func (c *ChannelGraph) IsPublicNode(pubKey [33]byte) (bool, error) {
 
 // genMultiSigP2WSH generates the p2wsh'd multisig script for 2 of 2 pubkeys.
 func genMultiSigP2WSH(aPub, bPub []byte) ([]byte, error) {
-	if len(aPub) != 33 || len(bPub) != 33 {
+	witnessScript, err := input.GenMultiSigScript(aPub, bPub)
-		return nil, fmt.Errorf("pubkey size error. Compressed " +
-			"pubkeys only")
-	}
-
-	// Swap to sort pubkeys if needed. Keys are sorted in lexicographical
-	// order. The signatures within the scriptSig must also adhere to the
-	// order, ensuring that the signatures for each public key appears in
-	// the proper order on the stack.
-	if bytes.Compare(aPub, bPub) == 1 {
-		aPub, bPub = bPub, aPub
-	}
-
-	// First, we'll generate the witness script for the multi-sig.
-	bldr := txscript.NewScriptBuilder()
-	bldr.AddOp(txscript.OP_2)
-	bldr.AddData(aPub) // Add both pubkeys (sorted).
-	bldr.AddData(bPub)
-	bldr.AddOp(txscript.OP_2)
-	bldr.AddOp(txscript.OP_CHECKMULTISIG)
-	witnessScript, err := bldr.Script()
 	if err != nil {
 		return nil, err
 	}
 
-	// With the witness script generated, we'll now turn it into a p2sh
+	// With the witness script generated, we'll now turn it into a p2wsh
 	// script:
 	//  * OP_0 <sha256(script)>
-	bldr = txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(
+		txscript.WithScriptAllocSize(input.P2WSHSize),
+	)
 	bldr.AddOp(txscript.OP_0)
 	scriptHash := sha256.Sum256(witnessScript)
 	bldr.AddData(scriptHash[:])

docs/release-notes/release-notes-0.16.1.md

@@ -47,6 +47,9 @@ https://github.com/lightningnetwork/lnd/pull/7359)
 * [Return `FEE_INSUFFICIENT` before checking balance for incoming low-fee
   HTLCs.](https://github.com/lightningnetwork/lnd/pull/7490).
 
+* Optimize script allocation size in order to save
+  [memory](https://github.com/lightningnetwork/lnd/pull/7464).
+
 ## Spec
 
 * [Add test vectors for

go.mod

@@ -3,7 +3,7 @@ module github.com/lightningnetwork/lnd
 require (
 	github.com/NebulousLabs/go-upnp v0.0.0-20180202185039-29b680b06c82
 	github.com/Yawning/aez v0.0.0-20211027044916-e49e68abd344
-	github.com/btcsuite/btcd v0.23.5-0.20230125025938-be056b0a0b2f
+	github.com/btcsuite/btcd v0.23.5-0.20230228185050-38331963bddd
 	github.com/btcsuite/btcd/btcec/v2 v2.3.2
 	github.com/btcsuite/btcd/btcutil v1.1.3
 	github.com/btcsuite/btcd/btcutil/psbt v1.1.8

go.sum

@@ -68,8 +68,8 @@ github.com/btcsuite/btcd v0.22.0-beta.0.20220207191057-4dc4ff7963b4/go.mod h1:7a
 github.com/btcsuite/btcd v0.23.0/go.mod h1:0QJIIN1wwIXF/3G/m87gIwGniDMDQqjVn4SZgnFpsYY=
 github.com/btcsuite/btcd v0.23.1/go.mod h1:0QJIIN1wwIXF/3G/m87gIwGniDMDQqjVn4SZgnFpsYY=
 github.com/btcsuite/btcd v0.23.3/go.mod h1:0QJIIN1wwIXF/3G/m87gIwGniDMDQqjVn4SZgnFpsYY=
-github.com/btcsuite/btcd v0.23.5-0.20230125025938-be056b0a0b2f h1:UJ/S/pV25+YsK0CJRJh8RDpTgy5h1oXWjOd4fp+opvY=
+github.com/btcsuite/btcd v0.23.5-0.20230228185050-38331963bddd h1:v2Bs8yLhwv+8XYU96OOnhZ5BEj8ZlNGownexUO0e80I=
-github.com/btcsuite/btcd v0.23.5-0.20230125025938-be056b0a0b2f/go.mod h1:0QJIIN1wwIXF/3G/m87gIwGniDMDQqjVn4SZgnFpsYY=
+github.com/btcsuite/btcd v0.23.5-0.20230228185050-38331963bddd/go.mod h1:0QJIIN1wwIXF/3G/m87gIwGniDMDQqjVn4SZgnFpsYY=
 github.com/btcsuite/btcd/btcec/v2 v2.1.0/go.mod h1:2VzYrv4Gm4apmbVVsSq5bqf1Ec8v56E48Vt0Y/umPgA=
 github.com/btcsuite/btcd/btcec/v2 v2.1.1/go.mod h1:ctjw4H1kknNJmRN4iP1R7bTQ+v3GJkZBd6mui8ZsAZE=
 github.com/btcsuite/btcd/btcec/v2 v2.1.3/go.mod h1:ctjw4H1kknNJmRN4iP1R7bTQ+v3GJkZBd6mui8ZsAZE=

input/script_utils.go

@@ -35,7 +35,9 @@ type Signature interface {
 // WitnessScriptHash generates a pay-to-witness-script-hash public key script
 // paying to a version 0 witness program paying to the passed redeem script.
 func WitnessScriptHash(witnessScript []byte) ([]byte, error) {
-	bldr := txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(
+		txscript.WithScriptAllocSize(P2WSHSize),
+	)
 
 	bldr.AddOp(txscript.OP_0)
 	scriptHash := sha256.Sum256(witnessScript)
@@ -47,7 +49,9 @@ func WitnessScriptHash(witnessScript []byte) ([]byte, error) {
 // paying to a version 0 witness program containing the passed serialized
 // public key.
 func WitnessPubKeyHash(pubkey []byte) ([]byte, error) {
-	bldr := txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(
+		txscript.WithScriptAllocSize(P2WPKHSize),
+	)
 
 	bldr.AddOp(txscript.OP_0)
 	pkhash := btcutil.Hash160(pubkey)
@@ -58,7 +62,9 @@ func WitnessPubKeyHash(pubkey []byte) ([]byte, error) {
 // GenerateP2SH generates a pay-to-script-hash public key script paying to the
 // passed redeem script.
 func GenerateP2SH(script []byte) ([]byte, error) {
-	bldr := txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(
+		txscript.WithScriptAllocSize(NestedP2WPKHSize),
+	)
 
 	bldr.AddOp(txscript.OP_HASH160)
 	scripthash := btcutil.Hash160(script)
@@ -70,7 +76,9 @@ func GenerateP2SH(script []byte) ([]byte, error) {
 // GenerateP2PKH generates a pay-to-public-key-hash public key script paying to
 // the passed serialized public key.
 func GenerateP2PKH(pubkey []byte) ([]byte, error) {
-	bldr := txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(
+		txscript.WithScriptAllocSize(P2PKHSize),
+	)
 
 	bldr.AddOp(txscript.OP_DUP)
 	bldr.AddOp(txscript.OP_HASH160)
@@ -96,7 +104,8 @@ func GenerateUnknownWitness() ([]byte, error) {
 // pubkeys.
 func GenMultiSigScript(aPub, bPub []byte) ([]byte, error) {
 	if len(aPub) != 33 || len(bPub) != 33 {
-		return nil, fmt.Errorf("pubkey size error: compressed pubkeys only")
+		return nil, fmt.Errorf("pubkey size error: compressed " +
+			"pubkeys only")
 	}
 
 	// Swap to sort pubkeys if needed. Keys are sorted in lexicographical
@@ -107,7 +116,9 @@ func GenMultiSigScript(aPub, bPub []byte) ([]byte, error) {
 		aPub, bPub = bPub, aPub
 	}
 
-	bldr := txscript.NewScriptBuilder()
+	bldr := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		MultiSigSize,
+	))
 	bldr.AddOp(txscript.OP_2)
 	bldr.AddData(aPub) // Add both pubkeys (sorted).
 	bldr.AddData(bPub)
@@ -241,7 +252,9 @@ func SenderHTLCScript(senderHtlcKey, receiverHtlcKey,
 	revocationKey *btcec.PublicKey, paymentHash []byte,
 	confirmedSpend bool) ([]byte, error) {
 
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		OfferedHtlcScriptSizeConfirmed,
+	))
 
 	// The opening operations are used to determine if this is the receiver
 	// of the HTLC attempting to sweep all the funds due to a contract
@@ -484,7 +497,9 @@ func ReceiverHTLCScript(cltvExpiry uint32, senderHtlcKey,
 	receiverHtlcKey, revocationKey *btcec.PublicKey,
 	paymentHash []byte, confirmedSpend bool) ([]byte, error) {
 
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		AcceptedHtlcScriptSizeConfirmed,
+	))
 
 	// The opening operations are used to determine if this is the sender
 	// of the HTLC attempting to sweep all the funds due to a contract
@@ -747,7 +762,9 @@ func ReceiverHtlcSpendTimeout(signer Signer, signDesc *SignDescriptor,
 func SecondLevelHtlcScript(revocationKey, delayKey *btcec.PublicKey,
 	csvDelay uint32) ([]byte, error) {
 
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		ToLocalScriptSize,
+	))
 
 	// If this is the revocation clause for this script is to be executed,
 	// the spender will push a 1, forcing us to hit the true clause of this
@@ -815,7 +832,9 @@ func SecondLevelHtlcScript(revocationKey, delayKey *btcec.PublicKey,
 func LeaseSecondLevelHtlcScript(revocationKey, delayKey *btcec.PublicKey,
 	csvDelay, cltvExpiry uint32) ([]byte, error) {
 
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		ToLocalScriptSize + LeaseWitnessScriptSizeOverhead,
+	))
 
 	// If this is the revocation clause for this script is to be executed,
 	// the spender will push a 1, forcing us to hit the true clause of this
@@ -998,7 +1017,9 @@ func CommitScriptToSelf(csvTimeout uint32, selfKey, revokeKey *btcec.PublicKey)
 	// have divulged the revocation hash, allowing them to homomorphically
 	// derive the proper private key which corresponds to the revoke public
 	// key.
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		ToLocalScriptSize,
+	))
 
 	builder.AddOp(txscript.OP_IF)
 
@@ -1054,7 +1075,9 @@ func LeaseCommitScriptToSelf(selfKey, revokeKey *btcec.PublicKey,
 	// have divulged the revocation hash, allowing them to homomorphically
 	// derive the proper private key which corresponds to the revoke public
 	// key.
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		ToLocalScriptSize + LeaseWitnessScriptSizeOverhead,
+	))
 
 	builder.AddOp(txscript.OP_IF)
 
@@ -1199,7 +1222,9 @@ func CommitSpendNoDelay(signer Signer, signDesc *SignDescriptor,
 // p2wkh output spendable immediately, requiring no contestation period.
 func CommitScriptUnencumbered(key *btcec.PublicKey) ([]byte, error) {
 	// This script goes to the "other" party, and is spendable immediately.
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		P2WPKHSize,
+	))
 	builder.AddOp(txscript.OP_0)
 	builder.AddData(btcutil.Hash160(key.SerializeCompressed()))
 
@@ -1219,7 +1244,9 @@ func CommitScriptUnencumbered(key *btcec.PublicKey) ([]byte, error) {
 //	<key> OP_CHECKSIGVERIFY
 //	1 OP_CHECKSEQUENCEVERIFY
 func CommitScriptToRemoteConfirmed(key *btcec.PublicKey) ([]byte, error) {
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		ToRemoteConfirmedScriptSize,
+	))
 
 	// Only the given key can spend the output.
 	builder.AddData(key.SerializeCompressed())
@@ -1248,7 +1275,7 @@ func CommitScriptToRemoteConfirmed(key *btcec.PublicKey) ([]byte, error) {
 func LeaseCommitScriptToRemoteConfirmed(key *btcec.PublicKey,
 	leaseExpiry uint32) ([]byte, error) {
 
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(45))
 
 	// Only the given key can spend the output.
 	builder.AddData(key.SerializeCompressed())
@@ -1310,7 +1337,9 @@ func CommitSpendToRemoteConfirmed(signer Signer, signDesc *SignDescriptor,
 //	  OP_16 OP_CSV
 //	OP_ENDIF
 func CommitScriptAnchor(key *btcec.PublicKey) ([]byte, error) {
-	builder := txscript.NewScriptBuilder()
+	builder := txscript.NewScriptBuilder(txscript.WithScriptAllocSize(
+		AnchorScriptSize,
+	))
 
 	// Spend immediately with key.
 	builder.AddData(key.SerializeCompressed())

input/script_utils_test.go

@@ -2034,3 +2034,215 @@ func TestSpecificationKeyDerivation(t *testing.T) {
 			actualRevocationPrivKeyHex)
 	}
 }
+
+// BenchmarkScriptBuilderAlloc benchmarks the script builder's default
+// allocation.
+func BenchmarkScriptBuilderAlloc(t *testing.B) {
+	dummyData := []byte("dummy data")
+	randomPriv, err := btcec.NewPrivateKey()
+	require.NoError(t, err)
+	randomPub := randomPriv.PubKey()
+	randomPubBytes := randomPub.SerializeCompressed()
+
+	t.ReportAllocs()
+	t.ResetTimer()
+
+	// We run each iteration 1000 times to make the script allocation stand
+	// out a bit more vs. the overhead of the rest of the function calls.
+	for i := 0; i < t.N*1000; i++ {
+		err := runScriptAllocTest(dummyData, randomPubBytes, randomPub)
+		if err != nil {
+			t.Fatal(err)
+		}
+	}
+}
+
+// TestScriptBuilderAlloc makes sure the scripts generated by the utils have the
+// correct length.
+func TestScriptBuilderAlloc(t *testing.T) {
+	t.Parallel()
+
+	dummyData := []byte("dummy data")
+	randomPriv, err := btcec.NewPrivateKey()
+	require.NoError(t, err)
+	randomPub := randomPriv.PubKey()
+	randomPubBytes := randomPub.SerializeCompressed()
+
+	err = runScriptAllocTest(dummyData, randomPubBytes, randomPub)
+	require.NoError(t, err)
+}
+
+// runScriptAllocTest runs the script size test. We don't use the "require"
+// library to assert the length to not influence the benchmark too much.
+func runScriptAllocTest(dummyData, randomPubBytes []byte,
+	randomPub *btcec.PublicKey) error {
+
+	const (
+		maxCLTV = 500000000
+		maxCSV  = (1 << 31) - 1
+	)
+	script, err := WitnessScriptHash(dummyData)
+	if err != nil {
+		return err
+	}
+	if len(script) != P2WSHSize {
+		return fmt.Errorf("expected script size of %d", P2WSHSize)
+	}
+
+	script, err = WitnessPubKeyHash(randomPubBytes)
+	if err != nil {
+		return err
+	}
+	if len(script) != P2WPKHSize {
+		return fmt.Errorf("expected script size of %d", P2WPKHSize)
+	}
+
+	script, err = GenerateP2SH(dummyData)
+	if err != nil {
+		return err
+	}
+	if len(script) != NestedP2WPKHSize {
+		return fmt.Errorf("expected script size of %d",
+			NestedP2WPKHSize)
+	}
+
+	script, err = GenerateP2PKH(dummyData)
+	if err != nil {
+		return err
+	}
+	if len(script) != P2PKHSize {
+		return fmt.Errorf("expected script size of %d", P2PKHSize)
+	}
+
+	script, err = GenMultiSigScript(randomPubBytes, randomPubBytes)
+	if err != nil {
+		return err
+	}
+	if len(script) != MultiSigSize {
+		return fmt.Errorf("expected script size of %d", MultiSigSize)
+	}
+
+	script, err = SenderHTLCScript(
+		randomPub, randomPub, randomPub, dummyData, false,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != OfferedHtlcScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			OfferedHtlcScriptSize)
+	}
+
+	script, err = SenderHTLCScript(
+		randomPub, randomPub, randomPub, dummyData, true,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != OfferedHtlcScriptSizeConfirmed {
+		return fmt.Errorf("expected script size of %d",
+			OfferedHtlcScriptSizeConfirmed)
+	}
+
+	script, err = ReceiverHTLCScript(
+		maxCLTV, randomPub, randomPub, randomPub, dummyData, false,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != AcceptedHtlcScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			AcceptedHtlcScriptSize)
+	}
+
+	script, err = ReceiverHTLCScript(
+		maxCLTV, randomPub, randomPub, randomPub, dummyData, true,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != AcceptedHtlcScriptSizeConfirmed {
+		return fmt.Errorf("expected script size of %d",
+			AcceptedHtlcScriptSizeConfirmed)
+	}
+
+	script, err = SecondLevelHtlcScript(randomPub, randomPub, maxCSV)
+	if err != nil {
+		return err
+	}
+	if len(script) != ToLocalScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			ToLocalScriptSize)
+	}
+
+	script, err = LeaseSecondLevelHtlcScript(
+		randomPub, randomPub, maxCSV, maxCLTV,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != ToLocalScriptSize+LeaseWitnessScriptSizeOverhead {
+		return fmt.Errorf("expected script size of %d",
+			ToLocalScriptSize+LeaseWitnessScriptSizeOverhead)
+	}
+
+	script, err = CommitScriptToSelf(maxCSV, randomPub, randomPub)
+	if err != nil {
+		return err
+	}
+	if len(script) != ToLocalScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			ToLocalScriptSize)
+	}
+
+	script, err = LeaseCommitScriptToSelf(
+		randomPub, randomPub, maxCSV, maxCLTV,
+	)
+	if err != nil {
+		return err
+	}
+	if len(script) != ToLocalScriptSize+LeaseWitnessScriptSizeOverhead {
+		return fmt.Errorf("expected script size of %d",
+			ToLocalScriptSize+LeaseWitnessScriptSizeOverhead)
+	}
+
+	script, err = CommitScriptUnencumbered(randomPub)
+	if err != nil {
+		return err
+	}
+	if len(script) != P2WPKHSize {
+		return fmt.Errorf("expected script size of %d", P2WPKHSize)
+	}
+
+	script, err = CommitScriptToRemoteConfirmed(randomPub)
+	if err != nil {
+		return err
+	}
+	if len(script) != ToRemoteConfirmedScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			ToRemoteConfirmedScriptSize)
+	}
+
+	script, err = LeaseCommitScriptToRemoteConfirmed(randomPub, maxCSV)
+	if err != nil {
+		return err
+	}
+	if len(script) !=
+		ToRemoteConfirmedScriptSize+LeaseWitnessScriptSizeOverhead {
+
+		return fmt.Errorf("expected script size of %d",
+			ToRemoteConfirmedScriptSize+
+				LeaseWitnessScriptSizeOverhead)
+	}
+
+	script, err = CommitScriptAnchor(randomPub)
+	if err != nil {
+		return err
+	}
+	if len(script) != AnchorScriptSize {
+		return fmt.Errorf("expected script size of %d",
+			AnchorScriptSize)
+	}
+
+	return nil
+}