lnrpc+routerrpc+lncli: add amt and fee limit msat fields

lnrpc/marshall_utils.go

@@ -1,10 +1,20 @@
 package lnrpc
 
 import (
+	"errors"
+
 	"github.com/btcsuite/btcutil"
 	"github.com/lightningnetwork/lnd/lnwire"
 )
 
+var (
+	// ErrSatMsatMutualExclusive is returned when both a sat and an msat
+	// amount are set.
+	ErrSatMsatMutualExclusive = errors.New(
+		"sat and msat arguments are mutually exclusive",
+	)
+)
+
 // CalculateFeeLimit returns the fee limit in millisatoshis. If a percentage
 // based fee limit has been requested, we'll factor in the ratio provided with
 // the amount of the payment.
@@ -18,6 +28,9 @@ func CalculateFeeLimit(feeLimit *FeeLimit,
 			btcutil.Amount(feeLimit.GetFixed()),
 		)
 
+	case *FeeLimit_FixedMsat:
+		return lnwire.MilliSatoshi(feeLimit.GetFixedMsat())
+
 	case *FeeLimit_Percent:
 		return amount * lnwire.MilliSatoshi(feeLimit.GetPercent()) / 100
 
@@ -28,3 +41,16 @@ func CalculateFeeLimit(feeLimit *FeeLimit,
 		return amount
 	}
 }
+
+// UnmarshallAmt returns a strong msat type for a sat/msat pair of rpc fields.
+func UnmarshallAmt(amtSat, amtMsat int64) (lnwire.MilliSatoshi, error) {
+	if amtSat != 0 && amtMsat != 0 {
+		return 0, ErrSatMsatMutualExclusive
+	}
+
+	if amtSat != 0 {
+		return lnwire.NewMSatFromSatoshis(btcutil.Amount(amtSat)), nil
+	}
+
+	return lnwire.MilliSatoshi(amtMsat), nil
+}