Release v0.3.0

vendor/github.com/muun/libwallet/swaps/v1.go

@@ -0,0 +1,151 @@
+package swaps
+
+import (
+	"bytes"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+
+	"github.com/btcsuite/btcd/txscript"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/btcsuite/btcutil"
+	"github.com/lightningnetwork/lnd/zpay32"
+	"github.com/muun/libwallet/addresses"
+)
+
+func (swap *SubmarineSwap) validateV1(rawInvoice string, userPublicKey, muunPublicKey *KeyDescriptor, network *chaincfg.Params) error {
+
+	invoice, err := zpay32.Decode(rawInvoice, network)
+	if err != nil {
+		return fmt.Errorf("failed to decode invoice: %w", err)
+	}
+
+	// Check the payment hash matches
+
+	serverPaymentHash, err := hex.DecodeString(swap.FundingOutput.ServerPaymentHashInHex)
+	if err != nil {
+		return fmt.Errorf("server payment hash is not valid hex: %w", err)
+	}
+
+	if !bytes.Equal(invoice.PaymentHash[:], serverPaymentHash) {
+		return fmt.Errorf("payment hash doesn't match %v != %v", hex.EncodeToString(invoice.PaymentHash[:]), swap.FundingOutput.ServerPaymentHashInHex)
+	}
+
+	// TODO: check that timelock is acceptable
+
+	// Validate that the refund address is one we can derive
+
+	swapRefundAddress := swap.FundingOutput.UserRefundAddress
+	derivedUserKey, err := userPublicKey.DeriveTo(swapRefundAddress.DerivationPath())
+	if err != nil {
+		return fmt.Errorf("failed to derive user key: %w", err)
+	}
+	derivedMuunKey, err := muunPublicKey.DeriveTo(swapRefundAddress.DerivationPath())
+	if err != nil {
+		return fmt.Errorf("failed to derive muun key: %w", err)
+	}
+
+	refundAddress, err := addresses.Create(
+		swapRefundAddress.Version(),
+		derivedUserKey,
+		derivedMuunKey,
+		swapRefundAddress.DerivationPath(),
+		network,
+	)
+	if err != nil {
+		return fmt.Errorf("failed to generate refund address: %w", err)
+	}
+
+	if refundAddress.Address() != swapRefundAddress.Address() {
+		return fmt.Errorf("refund address doesn't match generated (%v != %v)", swapRefundAddress.Address(), refundAddress.Address())
+	}
+
+	// Check the swap's witness script is a valid swap script
+
+	serverPubKey, err := hex.DecodeString(swap.FundingOutput.ServerPublicKeyInHex)
+	if err != nil {
+		return fmt.Errorf("server pub key is not hex: %w", err)
+	}
+
+	witnessScript, err := CreateWitnessScriptSubmarineSwapV1(
+		swapRefundAddress.Address(),
+		serverPaymentHash,
+		serverPubKey,
+		swap.FundingOutput.UserLockTime,
+		network)
+	if err != nil {
+		return fmt.Errorf("failed to compute witness script: %w", err)
+	}
+
+	redeemScript, err := createNonNativeSegwitRedeemScript(witnessScript)
+	if err != nil {
+		return fmt.Errorf("failed to build redeem script: %w", err)
+	}
+
+	address, err := btcutil.NewAddressScriptHash(redeemScript, network)
+	if err != nil {
+		return fmt.Errorf("failed to build address for swap script: %w", err)
+	}
+
+	if address.EncodeAddress() != swap.FundingOutput.OutputAddress {
+		return fmt.Errorf("address for swap script mismatch (%v != %v)", address.EncodeAddress(), swap.FundingOutput.OutputAddress)
+	}
+
+	if len(swap.PreimageInHex) > 0 {
+		preimage, err := hex.DecodeString(swap.PreimageInHex)
+		if err != nil {
+			return fmt.Errorf("preimagehex is not actually hex: %w", err)
+		}
+
+		calculatedPaymentHash := sha256.Sum256(preimage)
+		if !bytes.Equal(invoice.PaymentHash[:], calculatedPaymentHash[:]) {
+			return fmt.Errorf("payment hash doesn't match preimage (%v != hash(%v)", invoice.PaymentHash, swap.PreimageInHex)
+		}
+	}
+
+	return nil
+}
+
+func CreateWitnessScriptSubmarineSwapV1(refundAddress string, paymentHash []byte, swapServerPubKey []byte, lockTime int64, network *chaincfg.Params) ([]byte, error) {
+
+	// It turns out that the payment hash present in an invoice is just the SHA256 of the
+	// payment preimage, so we still have to do a pass of RIPEMD160 before pushing it to the
+	// script
+	paymentHash160 := ripemd160(paymentHash)
+	decodedRefundAddress, err := btcutil.DecodeAddress(refundAddress, network)
+	if err != nil {
+		return nil, fmt.Errorf("refund address is invalid: %w", err)
+	}
+
+	refundAddressHash := decodedRefundAddress.ScriptAddress()
+
+	builder := txscript.NewScriptBuilder()
+	builder.AddOp(txscript.OP_DUP)
+
+	// Condition to decide which branch to follow:
+	builder.AddOp(txscript.OP_HASH160).
+		AddData(paymentHash160).
+		AddOp(txscript.OP_EQUAL)
+
+	// SubmarineSwap service spending script, for successful LN payments:
+	builder.AddOp(txscript.OP_IF).
+		AddOp(txscript.OP_DROP).
+		AddData(swapServerPubKey)
+
+	// User spending script, for failed LN payments:
+	builder.AddOp(txscript.OP_ELSE).
+		AddInt64(lockTime).
+		AddOp(txscript.OP_CHECKLOCKTIMEVERIFY).
+		AddOp(txscript.OP_DROP).
+		AddOp(txscript.OP_DUP).
+		AddOp(txscript.OP_HASH160).
+		AddData(refundAddressHash).
+		AddOp(txscript.OP_EQUALVERIFY)
+
+	// Final verification for both branches:
+	builder.AddOp(txscript.OP_ENDIF).
+		AddOp(txscript.OP_CHECKSIG)
+
+	return builder.Script()
+}