funding+server: update switch after sending channel update

With this commit we give the funding manager the ability to inform the
switch about custom channel policies, right after we've announced the
channel to the network.
This change is necessary because before #6753 a channel could only be
opened with the default forwarding policies, so the switch automatically
had the "correct" default values. Since #6753 added the ability to
specify forwarding policies at channel open time, we announced those
policies to the network but never updated the switch to inform it about
the changed policies (previously changing the policies was only possible
through the UpdateChannelPolicy RPC which did call the switch).

funding/manager.go

@@ -488,6 +488,11 @@ type Config struct {
 	// transition from pending open to open.
 	NotifyOpenChannelEvent func(wire.OutPoint)
 
+	// UpdateForwardingPolicies is used by the manager to update active
+	// links with a new policy.
+	UpdateForwardingPolicies func(
+		chanPolicies map[wire.OutPoint]htlcswitch.ForwardingPolicy)
+
 	// 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.
@@ -3159,6 +3164,28 @@ func (f *Manager) addToRouterGraph(completeChan *channeldb.OpenChannel,
 		return ErrFundingManagerShuttingDown
 	}
 
+	// The user can define non-default channel policies when opening a
+	// channel. They are stored in the database to be persisted from the
+	// moment of funding the channel to it being confirmed. We just
+	// announced those policies to the network, but we also need to update
+	// our local policy in the switch to make sure we can forward payments
+	// with the correct fees. We can't do this when creating the link
+	// initially as that only takes the static channel parameters.
+	updatedPolicy := map[wire.OutPoint]htlcswitch.ForwardingPolicy{
+		completeChan.FundingOutpoint: {
+			MinHTLCOut: ann.chanUpdateAnn.HtlcMinimumMsat,
+			MaxHTLC:    ann.chanUpdateAnn.HtlcMaximumMsat,
+			BaseFee: lnwire.MilliSatoshi(
+				ann.chanUpdateAnn.BaseFee,
+			),
+			FeeRate: lnwire.MilliSatoshi(
+				ann.chanUpdateAnn.FeeRate,
+			),
+			TimeLockDelta: uint32(ann.chanUpdateAnn.TimeLockDelta),
+		},
+	}
+	f.cfg.UpdateForwardingPolicies(updatedPolicy)
+
 	return nil
 }
 
@@ -3729,7 +3756,7 @@ func (f *Manager) newChanAnnouncement(localPubKey,
 		chanUpdateAnn.FeeRate = uint32(storedFwdingPolicy.FeeRate)
 
 	default:
-		log.Infof("No channel forwaring policy specified for channel "+
+		log.Infof("No channel forwarding policy specified for channel "+
 			"announcement of ChannelID(%v). "+
 			"Assuming default fee parameters.", chanID)
 		chanUpdateAnn.BaseFee = uint32(

funding/manager_test.go

@@ -250,6 +250,7 @@ type testNode struct {
 	testDir         string
 	shutdownChannel chan struct{}
 	reportScidChan  chan struct{}
+	updatedPolicies chan map[wire.OutPoint]htlcswitch.ForwardingPolicy
 	localFeatures   []lnwire.FeatureBit
 	remoteFeatures  []lnwire.FeatureBit
 
@@ -368,6 +369,9 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 	publTxChan := make(chan *wire.MsgTx, 1)
 	shutdownChan := make(chan struct{})
 	reportScidChan := make(chan struct{})
+	updatedPolicies := make(
+		chan map[wire.OutPoint]htlcswitch.ForwardingPolicy, 1,
+	)
 
 	wc := &mock.WalletController{
 		RootKey: alicePrivKey,
@@ -524,6 +528,11 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 			return nil, nil
 		},
 		AliasManager: aliasMgr,
+		UpdateForwardingPolicies: func(
+			p map[wire.OutPoint]htlcswitch.ForwardingPolicy) {
+
+			updatedPolicies <- p
+		},
 	}
 
 	for _, op := range options {
@@ -548,6 +557,7 @@ func createTestFundingManager(t *testing.T, privKey *btcec.PrivateKey,
 		testDir:         tempTestDir,
 		shutdownChannel: shutdownChan,
 		reportScidChan:  reportScidChan,
+		updatedPolicies: updatedPolicies,
 		addr:            addr,
 	}
 
@@ -627,11 +637,12 @@ func recreateAliceFundingManager(t *testing.T, alice *testNode) {
 		UpdateLabel: func(chainhash.Hash, string) error {
 			return nil
 		},
-		ZombieSweeperInterval: oldCfg.ZombieSweeperInterval,
-		ReservationTimeout:    oldCfg.ReservationTimeout,
-		OpenChannelPredicate:  chainedAcceptor,
-		DeleteAliasEdge:       oldCfg.DeleteAliasEdge,
-		AliasManager:          oldCfg.AliasManager,
+		ZombieSweeperInterval:    oldCfg.ZombieSweeperInterval,
+		ReservationTimeout:       oldCfg.ReservationTimeout,
+		OpenChannelPredicate:     chainedAcceptor,
+		DeleteAliasEdge:          oldCfg.DeleteAliasEdge,
+		AliasManager:             oldCfg.AliasManager,
+		UpdateForwardingPolicies: oldCfg.UpdateForwardingPolicies,
 	})
 	require.NoError(t, err, "failed recreating aliceFundingManager")
 
@@ -1119,6 +1130,21 @@ func assertChannelAnnouncements(t *testing.T, alice, bob *testNode,
 			}
 		}
 
+		// At this point we should also have gotten a policy update that
+		// was sent to the switch subsystem. Make sure it contains the
+		// same values.
+		var policyUpdate htlcswitch.ForwardingPolicy
+		select {
+		case policyUpdateMap := <-node.updatedPolicies:
+			require.Len(t, policyUpdateMap, 1)
+			for _, policy := range policyUpdateMap {
+				policyUpdate = policy
+			}
+
+		case <-time.After(time.Second * 5):
+			t.Fatalf("node didn't send policy update")
+		}
+
 		gotChannelAnnouncement := false
 		gotChannelUpdate := false
 		for _, msg := range announcements {
@@ -1147,24 +1173,34 @@ func assertChannelAnnouncements(t *testing.T, alice, bob *testNode,
 					minHtlc = customMinHtlc[j]
 				}
 				require.Equal(t, minHtlc, m.HtlcMinimumMsat)
+				require.Equal(
+					t, minHtlc, policyUpdate.MinHTLCOut,
+				)
 
 				// We might expect a custom MaxHltc value.
 				if len(customMaxHtlc) > 0 {
 					maxHtlc = customMaxHtlc[j]
 				}
 				require.Equal(t, maxHtlc, m.HtlcMaximumMsat)
+				require.Equal(t, maxHtlc, policyUpdate.MaxHTLC)
 
 				// We might expect a custom baseFee value.
 				if len(baseFees) > 0 {
 					baseFee = baseFees[j]
 				}
 				require.EqualValues(t, baseFee, m.BaseFee)
+				require.EqualValues(
+					t, baseFee, policyUpdate.BaseFee,
+				)
 
 				// We might expect a custom feeRate value.
 				if len(feeRates) > 0 {
 					feeRate = feeRates[j]
 				}
 				require.EqualValues(t, feeRate, m.FeeRate)
+				require.EqualValues(
+					t, feeRate, policyUpdate.FeeRate,
+				)
 
 				gotChannelUpdate = true
 			}

server.go

@@ -1439,8 +1439,9 @@ func newServer(cfg *Config, listenAddrs []net.Addr,
 		RegisteredChains:              cfg.registeredChains,
 		MaxAnchorsCommitFeeRate: chainfee.SatPerKVByte(
 			s.cfg.MaxCommitFeeRateAnchors * 1000).FeePerKWeight(),
-		DeleteAliasEdge: deleteAliasEdge,
-		AliasManager:    s.aliasMgr,
+		DeleteAliasEdge:          deleteAliasEdge,
+		AliasManager:             s.aliasMgr,
+		UpdateForwardingPolicies: s.htlcSwitch.UpdateForwardingPolicies,
 	})
 	if err != nil {
 		return nil, err