From 4d02100e128d8c929e5a13ecdab8ab7342e1e009 Mon Sep 17 00:00:00 2001
From: nsa <elzeigel@gmail.com>
Date: Wed, 7 Aug 2019 22:18:23 -0400
Subject: [PATCH] fundingmanager+server: adding ChannelAcceptor to the
 fundingmanager

---
 fundingmanager.go      | 24 +++++++++++++++++++++++-
 fundingmanager_test.go |  7 +++++++
 lnd.go                 |  2 +-
 server.go              |  6 +++++-
 4 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/fundingmanager.go b/fundingmanager.go
index db159fae3..f2a321eff 100644
--- a/fundingmanager.go
+++ b/fundingmanager.go
@@ -15,6 +15,7 @@ import (
 	"github.com/davecgh/go-spew/spew"
 	"github.com/go-errors/errors"
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/chanacceptor"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/htlcswitch"
@@ -338,6 +339,11 @@ type fundingConfig struct {
 	// NotifyOpenChannelEvent informs the ChannelNotifier when channels
 	// transition from pending open to open.
 	NotifyOpenChannelEvent func(wire.OutPoint)
+
+	// OpenChannelPredicate is a predicate on the lnwire.OpenChannel message
+	// and on the requesting node's public key that returns a bool which tells
+	// the funding manager whether or not to accept the channel.
+	OpenChannelPredicate chanacceptor.ChannelAcceptor
 }
 
 // fundingManager acts as an orchestrator/bridge between the wallet's
@@ -1057,7 +1063,23 @@ func (f *fundingManager) handleFundingOpen(fmsg *fundingOpenMsg) {
 	if f.cfg.RejectPush && msg.PushAmount > 0 {
 		f.failFundingFlow(
 			fmsg.peer, fmsg.msg.PendingChannelID,
-			lnwallet.ErrNonZeroPushAmount())
+			lnwallet.ErrNonZeroPushAmount(),
+		)
+		return
+	}
+
+	// Send the OpenChannel request to the ChannelAcceptor to determine whether
+	// this node will accept the channel.
+	chanReq := &chanacceptor.ChannelAcceptRequest{
+		Node:        fmsg.peer.IdentityKey(),
+		OpenChanMsg: fmsg.msg,
+	}
+
+	if !f.cfg.OpenChannelPredicate.Accept(chanReq) {
+		f.failFundingFlow(
+			fmsg.peer, fmsg.msg.PendingChannelID,
+			fmt.Errorf("open channel request rejected"),
+		)
 		return
 	}
 
diff --git a/fundingmanager_test.go b/fundingmanager_test.go
index 4fb31ee88..f5e3fa5bc 100644
--- a/fundingmanager_test.go
+++ b/fundingmanager_test.go
@@ -23,6 +23,7 @@ import (
 	"github.com/btcsuite/btcutil"
 
 	"github.com/lightningnetwork/lnd/chainntnfs"
+	"github.com/lightningnetwork/lnd/chanacceptor"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/discovery"
 	"github.com/lightningnetwork/lnd/htlcswitch"
@@ -281,6 +282,8 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 
 	var chanIDSeed [32]byte
 
+	chainedAcceptor := chanacceptor.NewChainedAcceptor()
+
 	fundingCfg := fundingConfig{
 		IDKey:        privKey.PubKey(),
 		Wallet:       lnw,
@@ -364,6 +367,7 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 		ReservationTimeout:     1 * time.Nanosecond,
 		MaxPendingChannels:     DefaultMaxPendingChannels,
 		NotifyOpenChannelEvent: func(wire.OutPoint) {},
+		OpenChannelPredicate:   chainedAcceptor,
 	}
 
 	for _, op := range options {
@@ -414,6 +418,8 @@ func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 
 	oldCfg := alice.fundingMgr.cfg
 
+	chainedAcceptor := chanacceptor.NewChainedAcceptor()
+
 	f, err := newFundingManager(fundingConfig{
 		IDKey:        oldCfg.IDKey,
 		Wallet:       oldCfg.Wallet,
@@ -458,6 +464,7 @@ func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 		},
 		ZombieSweeperInterval: oldCfg.ZombieSweeperInterval,
 		ReservationTimeout:    oldCfg.ReservationTimeout,
+		OpenChannelPredicate:  chainedAcceptor,
 	})
 	if err != nil {
 		t.Fatalf("failed recreating aliceFundingManager: %v", err)
diff --git a/lnd.go b/lnd.go
index ee260bfdb..0d5ab7f11 100644
--- a/lnd.go
+++ b/lnd.go
@@ -496,7 +496,7 @@ func Main(lisCfg ListenerCfg) error {
 	// connections.
 	server, err := newServer(
 		cfg.Listeners, chanDB, towerClientDB, activeChainControl,
-		idPrivKey, walletInitParams.ChansToRestore,
+		idPrivKey, walletInitParams.ChansToRestore, chainedAcceptor,
 	)
 	if err != nil {
 		err := fmt.Errorf("Unable to create server: %v", err)
diff --git a/server.go b/server.go
index cba866875..05d8bed5b 100644
--- a/server.go
+++ b/server.go
@@ -28,6 +28,7 @@ import (
 	sphinx "github.com/lightningnetwork/lightning-onion"
 	"github.com/lightningnetwork/lnd/autopilot"
 	"github.com/lightningnetwork/lnd/brontide"
+	"github.com/lightningnetwork/lnd/chanacceptor"
 	"github.com/lightningnetwork/lnd/chanbackup"
 	"github.com/lightningnetwork/lnd/channeldb"
 	"github.com/lightningnetwork/lnd/channelnotifier"
@@ -297,7 +298,8 @@ func noiseDial(idPriv *btcec.PrivateKey) func(net.Addr) (net.Conn, error) {
 func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 	towerClientDB *wtdb.ClientDB, cc *chainControl,
 	privKey *btcec.PrivateKey,
-	chansToRestore walletunlocker.ChannelsToRecover) (*server, error) {
+	chansToRestore walletunlocker.ChannelsToRecover,
+	chanPredicate chanacceptor.ChannelAcceptor) (*server, error) {
 
 	var err error
 
@@ -908,6 +910,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 	if _, err := rand.Read(chanIDSeed[:]); err != nil {
 		return nil, err
 	}
+
 	s.fundingMgr, err = newFundingManager(fundingConfig{
 		IDKey:              privKey.PubKey(),
 		Wallet:             cc.wallet,
@@ -1069,6 +1072,7 @@ func newServer(listenAddrs []net.Addr, chanDB *channeldb.DB,
 		MaxPendingChannels:     cfg.MaxPendingChannels,
 		RejectPush:             cfg.RejectPush,
 		NotifyOpenChannelEvent: s.channelNotifier.NotifyOpenChannelEvent,
+		OpenChannelPredicate:   chanPredicate,
 	})
 	if err != nil {
 		return nil, err