utils: add htlc & swap related helpers

Author: GeorgeTsagk

client.go

@@ -17,6 +17,7 @@ import (
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
 	"github.com/lightninglabs/loop/sweep"
+	"github.com/lightninglabs/loop/utils"
 	"github.com/lightningnetwork/lnd/lntypes"
 	"github.com/lightningnetwork/lnd/routing/route"
 	"google.golang.org/grpc"
@@ -232,7 +233,7 @@ func (s *Client) FetchSwaps(ctx context.Context) ([]*SwapInfo, error) {
 			LastUpdate:    swp.LastUpdateTime(),
 		}
 
-		htlc, err := GetHtlc(
+		htlc, err := utils.GetHtlc(
 			swp.Hash, &swp.Contract.SwapContract,
 			s.lndServices.ChainParams,
 		)
@@ -265,7 +266,7 @@ func (s *Client) FetchSwaps(ctx context.Context) ([]*SwapInfo, error) {
 			LastUpdate:    swp.LastUpdateTime(),
 		}
 
-		htlc, err := GetHtlc(
+		htlc, err := utils.GetHtlc(
 			swp.Hash, &swp.Contract.SwapContract,
 			s.lndServices.ChainParams,
 		)
@@ -540,7 +541,7 @@ func (s *Client) getLoopOutSweepFee(ctx context.Context, confTarget int32) (
 		return 0, err
 	}
 
-	scriptVersion := GetHtlcScriptVersion(
+	scriptVersion := utils.GetHtlcScriptVersion(
 		loopdb.CurrentProtocolVersion(),
 	)
 
@@ -731,7 +732,7 @@ func (s *Client) estimateFee(ctx context.Context, amt btcutil.Amount,
 	// Generate a dummy address for fee estimation.
 	witnessProg := [32]byte{}
 
-	scriptVersion := GetHtlcScriptVersion(
+	scriptVersion := utils.GetHtlcScriptVersion(
 		loopdb.CurrentProtocolVersion(),
 	)
 

loopd/view.go

@@ -8,6 +8,7 @@ import (
 	"github.com/lightninglabs/lndclient"
 	"github.com/lightninglabs/loop"
 	"github.com/lightninglabs/loop/loopdb"
+	"github.com/lightninglabs/loop/utils"
 )
 
 // view prints all swaps currently in the database.
@@ -56,7 +57,7 @@ func viewOut(swapClient *loop.Client, chainParams *chaincfg.Params) error {
 	for _, s := range swaps {
 		s := s
 
-		htlc, err := loop.GetHtlc(
+		htlc, err := utils.GetHtlc(
 			s.Hash, &s.Contract.SwapContract, chainParams,
 		)
 		if err != nil {
@@ -107,7 +108,7 @@ func viewIn(swapClient *loop.Client, chainParams *chaincfg.Params) error {
 	for _, s := range swaps {
 		s := s
 
-		htlc, err := loop.GetHtlc(
+		htlc, err := utils.GetHtlc(
 			s.Hash, &s.Contract.SwapContract, chainParams,
 		)
 		if err != nil {

loopin.go

@@ -18,6 +18,7 @@ import (
 	"github.com/lightninglabs/loop/labels"
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
+	"github.com/lightninglabs/loop/utils"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	invpkg "github.com/lightningnetwork/lnd/invoices"
 	"github.com/lightningnetwork/lnd/keychain"
@@ -442,7 +443,7 @@ func validateLoopInContract(height int32, response *newLoopInResponse) error {
 // initHtlcs creates and updates the native and nested segwit htlcs of the
 // loopInSwap.
 func (s *loopInSwap) initHtlcs() error {
-	htlc, err := GetHtlc(
+	htlc, err := utils.GetHtlc(
 		s.hash, &s.SwapContract, s.swapKit.lnd.ChainParams,
 	)
 	if err != nil {

loopout.go

@@ -22,12 +22,12 @@ import (
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
 	"github.com/lightninglabs/loop/sweep"
+	"github.com/lightninglabs/loop/utils"
 	"github.com/lightningnetwork/lnd/chainntnfs"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/input"
 	"github.com/lightningnetwork/lnd/lnrpc"
 	"github.com/lightningnetwork/lnd/lntypes"
-	"github.com/lightningnetwork/lnd/zpay32"
 )
 
 const (
@@ -207,7 +207,7 @@ func newLoopOutSwap(globalCtx context.Context, cfg *swapConfig,
 	swapKit.lastUpdateTime = initiationTime
 
 	// Create the htlc.
-	htlc, err := GetHtlc(
+	htlc, err := utils.GetHtlc(
 		swapKit.hash, swapKit.contract, swapKit.lnd.ChainParams,
 	)
 	if err != nil {
@@ -220,7 +220,9 @@ func newLoopOutSwap(globalCtx context.Context, cfg *swapConfig,
 
 	// Obtain the payment addr since we'll need it later for routing plugin
 	// recommendation and possibly for cancel.
-	paymentAddr, err := obtainSwapPaymentAddr(contract.SwapInvoice, cfg)
+	paymentAddr, err := utils.ObtainSwapPaymentAddr(
+		contract.SwapInvoice, cfg.lnd.ChainParams,
+	)
 	if err != nil {
 		return nil, err
 	}
@@ -263,7 +265,7 @@ func resumeLoopOutSwap(cfg *swapConfig, pend *loopdb.LoopOut,
 	)
 
 	// Create the htlc.
-	htlc, err := GetHtlc(
+	htlc, err := utils.GetHtlc(
 		swapKit.hash, swapKit.contract, swapKit.lnd.ChainParams,
 	)
 	if err != nil {
@@ -275,8 +277,8 @@ func resumeLoopOutSwap(cfg *swapConfig, pend *loopdb.LoopOut,
 
 	// Obtain the payment addr since we'll need it later for routing plugin
 	// recommendation and possibly for cancel.
-	paymentAddr, err := obtainSwapPaymentAddr(
-		pend.Contract.SwapInvoice, cfg,
+	paymentAddr, err := utils.ObtainSwapPaymentAddr(
+		pend.Contract.SwapInvoice, cfg.lnd.ChainParams,
 	)
 	if err != nil {
 		return nil, err
@@ -302,24 +304,6 @@ func resumeLoopOutSwap(cfg *swapConfig, pend *loopdb.LoopOut,
 	return swap, nil
 }
 
-// obtainSwapPaymentAddr will retrieve the payment addr from the passed invoice.
-func obtainSwapPaymentAddr(swapInvoice string, cfg *swapConfig) (
-	*[32]byte, error) {
-
-	swapPayReq, err := zpay32.Decode(
-		swapInvoice, cfg.lnd.ChainParams,
-	)
-	if err != nil {
-		return nil, err
-	}
-
-	if swapPayReq.PaymentAddr == nil {
-		return nil, fmt.Errorf("expected payment address for invoice")
-	}
-
-	return swapPayReq.PaymentAddr, nil
-}
-
 // sendUpdate reports an update to the swap state.
 func (s *loopOutSwap) sendUpdate(ctx context.Context) error {
 	info := s.swapInfo()

swap.go

@@ -4,11 +4,10 @@ import (
 	"context"
 	"time"
 
-	"github.com/btcsuite/btcd/chaincfg"
 	"github.com/lightninglabs/lndclient"
 	"github.com/lightninglabs/loop/loopdb"
 	"github.com/lightninglabs/loop/swap"
-	"github.com/lightningnetwork/lnd/input"
+	"github.com/lightninglabs/loop/utils"
 	"github.com/lightningnetwork/lnd/lntypes"
 )
 
@@ -50,59 +49,10 @@ func newSwapKit(hash lntypes.Hash, swapType swap.Type, cfg *swapConfig,
 	}
 }
 
-// GetHtlcScriptVersion returns the correct HTLC script version for the passed
-// protocol version.
-func GetHtlcScriptVersion(
-	protocolVersion loopdb.ProtocolVersion) swap.ScriptVersion {
-
-	// If the swap was initiated before we had our v3 script, use v2.
-	if protocolVersion < loopdb.ProtocolVersionHtlcV3 ||
-		protocolVersion == loopdb.ProtocolVersionUnrecorded {
-
-		return swap.HtlcV2
-	}
-
-	return swap.HtlcV3
-}
-
 // IsTaproot returns true if the swap referenced by the passed swap contract
 // uses the v3 (taproot) htlc.
 func IsTaprootSwap(swapContract *loopdb.SwapContract) bool {
-	return GetHtlcScriptVersion(swapContract.ProtocolVersion) == swap.HtlcV3
-}
-
-// GetHtlc composes and returns the on-chain swap script.
-func GetHtlc(hash lntypes.Hash, contract *loopdb.SwapContract,
-	chainParams *chaincfg.Params) (*swap.Htlc, error) {
-
-	switch GetHtlcScriptVersion(contract.ProtocolVersion) {
-	case swap.HtlcV2:
-		return swap.NewHtlcV2(
-			contract.CltvExpiry, contract.HtlcKeys.SenderScriptKey,
-			contract.HtlcKeys.ReceiverScriptKey, hash,
-			chainParams,
-		)
-
-	case swap.HtlcV3:
-		// Swaps that implement the new MuSig2 protocol will be expected
-		// to use the 1.0RC2 MuSig2 key derivation scheme.
-		muSig2Version := input.MuSig2Version040
-		if contract.ProtocolVersion >= loopdb.ProtocolVersionMuSig2 {
-			muSig2Version = input.MuSig2Version100RC2
-		}
-
-		return swap.NewHtlcV3(
-			muSig2Version,
-			contract.CltvExpiry,
-			contract.HtlcKeys.SenderInternalPubKey,
-			contract.HtlcKeys.ReceiverInternalPubKey,
-			contract.HtlcKeys.SenderScriptKey,
-			contract.HtlcKeys.ReceiverScriptKey,
-			hash, chainParams,
-		)
-	}
-
-	return nil, swap.ErrInvalidScriptVersion
+	return utils.GetHtlcScriptVersion(swapContract.ProtocolVersion) == swap.HtlcV3
 }
 
 // swapInfo constructs and returns a filled SwapInfo from

utils/htlc_utils.go

@@ -0,0 +1,77 @@
+package utils
+
+import (
+	"fmt"
+
+	"github.com/btcsuite/btcd/chaincfg"
+	"github.com/lightninglabs/loop/loopdb"
+	"github.com/lightninglabs/loop/swap"
+	"github.com/lightningnetwork/lnd/input"
+	"github.com/lightningnetwork/lnd/lntypes"
+	"github.com/lightningnetwork/lnd/zpay32"
+)
+
+// GetHtlc composes and returns the on-chain swap script.
+func GetHtlc(hash lntypes.Hash, contract *loopdb.SwapContract,
+	chainParams *chaincfg.Params) (*swap.Htlc, error) {
+
+	switch GetHtlcScriptVersion(contract.ProtocolVersion) {
+	case swap.HtlcV2:
+		return swap.NewHtlcV2(
+			contract.CltvExpiry, contract.HtlcKeys.SenderScriptKey,
+			contract.HtlcKeys.ReceiverScriptKey, hash,
+			chainParams,
+		)
+
+	case swap.HtlcV3:
+		// Swaps that implement the new MuSig2 protocol will be expected
+		// to use the 1.0RC2 MuSig2 key derivation scheme.
+		muSig2Version := input.MuSig2Version040
+		if contract.ProtocolVersion >= loopdb.ProtocolVersionMuSig2 {
+			muSig2Version = input.MuSig2Version100RC2
+		}
+
+		return swap.NewHtlcV3(
+			muSig2Version,
+			contract.CltvExpiry,
+			contract.HtlcKeys.SenderInternalPubKey,
+			contract.HtlcKeys.ReceiverInternalPubKey,
+			contract.HtlcKeys.SenderScriptKey,
+			contract.HtlcKeys.ReceiverScriptKey,
+			hash, chainParams,
+		)
+	}
+
+	return nil, swap.ErrInvalidScriptVersion
+}
+
+// GetHtlcScriptVersion returns the correct HTLC script version for the passed
+// protocol version.
+func GetHtlcScriptVersion(
+	protocolVersion loopdb.ProtocolVersion) swap.ScriptVersion {
+
+	// If the swap was initiated before we had our v3 script, use v2.
+	if protocolVersion < loopdb.ProtocolVersionHtlcV3 ||
+		protocolVersion == loopdb.ProtocolVersionUnrecorded {
+
+		return swap.HtlcV2
+	}
+
+	return swap.HtlcV3
+}
+
+// ObtainSwapPaymentAddr will retrieve the payment addr from the passed invoice.
+func ObtainSwapPaymentAddr(swapInvoice string, chainParams *chaincfg.Params) (
+	*[32]byte, error) {
+
+	swapPayReq, err := zpay32.Decode(swapInvoice, chainParams)
+	if err != nil {
+		return nil, err
+	}
+
+	if swapPayReq.PaymentAddr == nil {
+		return nil, fmt.Errorf("expected payment address for invoice")
+	}
+
+	return swapPayReq.PaymentAddr, nil
+}