From 44384a1b5be314f6a2b0275f2cb367e3cffaca9b Mon Sep 17 00:00:00 2001
From: "Johan T. Halseth" <johanth@gmail.com>
Date: Thu, 11 Jul 2019 13:14:36 +0200
Subject: [PATCH] lnwallet: move coin selection before ChannelReservation

Now that coin selection is independent of creating the channel
reservation, we can move it first, in preparation for doing custom coin
selection.
---
 lnwallet/interface_test.go |  8 +++----
 lnwallet/wallet.go         | 44 +++++++++++++++++++++++---------------
 2 files changed, 31 insertions(+), 21 deletions(-)

diff --git a/lnwallet/interface_test.go b/lnwallet/interface_test.go
index 866e79e4..ac650778 100644
--- a/lnwallet/interface_test.go
+++ b/lnwallet/interface_test.go
@@ -753,9 +753,9 @@ func testCancelNonExistentReservation(miner *rpctest.Harness,
 func testReservationInitiatorBalanceBelowDustCancel(miner *rpctest.Harness,
 	alice, _ *lnwallet.LightningWallet, t *testing.T) {
 
-	// We'll attempt to create a new reservation with an extremely high fee
-	// rate. This should push our balance into the negative and result in a
-	// failure to create the reservation.
+	// We'll attempt to create a new reservation with an extremely high
+	// commitment fee rate. This should push our balance into the negative
+	// and result in a failure to create the reservation.
 	const numBTC = 4
 	fundingAmount, err := btcutil.NewAmount(numBTC)
 	if err != nil {
@@ -772,7 +772,7 @@ func testReservationInitiatorBalanceBelowDustCancel(miner *rpctest.Harness,
 		LocalFundingAmt:  fundingAmount,
 		RemoteFundingAmt: 0,
 		CommitFeePerKw:   feePerKw,
-		FundingFeePerKw:  feePerKw,
+		FundingFeePerKw:  1000,
 		PushMSat:         0,
 		Flags:            lnwire.FFAnnounceChannel,
 	}
diff --git a/lnwallet/wallet.go b/lnwallet/wallet.go
index 57fa5b21..122c7a2e 100644
--- a/lnwallet/wallet.go
+++ b/lnwallet/wallet.go
@@ -453,6 +453,29 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 	capacity := req.LocalFundingAmt + req.RemoteFundingAmt
 	localFundingAmt := req.LocalFundingAmt
 
+	var (
+		selected *coinSelection
+		err      error
+	)
+
+	// If we're on the receiving end of a single funder channel then we
+	// don't need to perform any coin selection, and the remote contributes
+	// all funds. Otherwise, attempt to obtain enough coins to meet the
+	// required funding amount.
+	if req.LocalFundingAmt != 0 {
+		// Coin selection is done on the basis of sat/kw, so we'll use
+		// the fee rate passed in to perform coin selection.
+		var err error
+		selected, err = l.selectCoinsAndChange(
+			req.FundingFeePerKw, req.LocalFundingAmt, req.MinConfs,
+		)
+		if err != nil {
+			req.err <- err
+			req.resp <- nil
+			return
+		}
+	}
+
 	id := atomic.AddUint64(&l.nextFundingID, 1)
 	reservation, err := NewChannelReservation(
 		capacity, localFundingAmt, req.CommitFeePerKw, l, id,
@@ -468,27 +491,14 @@ func (l *LightningWallet) handleFundingReserveRequest(req *InitFundingReserveMsg
 	reservation.Lock()
 	defer reservation.Unlock()
 
-	reservation.nodeAddr = req.NodeAddr
-	reservation.partialState.IdentityPub = req.NodeID
-
-	// If we're on the receiving end of a single funder channel then we
-	// don't need to perform any coin selection. Otherwise, attempt to
-	// obtain enough coins to meet the required funding amount.
-	if req.LocalFundingAmt != 0 {
-		// Coin selection is done on the basis of sat/kw, so we'll use
-		// the fee rate passed in to perform coin selection.
-		selected, err := l.selectCoinsAndChange(
-			req.FundingFeePerKw, req.LocalFundingAmt, req.MinConfs,
-		)
-		if err != nil {
-			req.err <- err
-			req.resp <- nil
-			return
-		}
+	if selected != nil {
 		reservation.ourContribution.Inputs = selected.coins
 		reservation.ourContribution.ChangeOutputs = selected.change
 	}
 
+	reservation.nodeAddr = req.NodeAddr
+	reservation.partialState.IdentityPub = req.NodeID
+
 	// Next, we'll grab a series of keys from the wallet which will be used
 	// for the duration of the channel. The keys include: our multi-sig
 	// key, the base revocation key, the base htlc key,the base payment