lnd: remove deprecated endpoints sendpayment, sendtoroute, sendtoroutesync, and sendpaymentsync.

This pull request removes the deprecated endpoints `sendpayment`, `sendtoroute`, `sendtoroutesync`,
and `sendpaymentsync` in `lightning.proto`, `rpcserver.go`, `lntest/rpc/lnd.go`, and its related test cases in `itest/lnd_routing_test.go` and `itest/lnd_channel_policy_test.go`.

docs: Update release notes for 0.18.0

Added release note in version 0.18.0 to notify about the upcoming removal of deprecated endpoints (`sendpayment`, `sendtoroute`, `sendtoroutesync`, and `sendpaymentsync`). Referenced PR (#8348) for more details.

Author: mohamedawnallah

docs/release-notes/release-notes-0.18.0.md

@@ -207,6 +207,8 @@
 * [Remove database pointers](https://github.com/lightningnetwork/lnd/pull/8117) 
   from channeldb schema structs.
 
+* Deprecated Endpoints Removal Preparation: In preparation for the next release (0.19.0), deprecated endpoints (`sendpayment`, `sendtoroute`, `sendtoroutesync`, and `sendpaymentsync`) will be removed. Developers are encouraged to update their implementations accordingly (if any). See PR (https://github.com/lightningnetwork/lnd/pull/8348) for more details.
+
 ## Tooling and Documentation
 
 # Contributors (Alphabetical Order)

itest/lnd_channel_policy_test.go

@@ -172,29 +172,12 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 	routes.Routes[0].Hops[1].AmtToForward = amtSat
 	routes.Routes[0].Hops[1].AmtToForwardMsat = amtMSat
 
-	// Send the payment with the modified value.
-	alicePayStream := alice.RPC.SendToRoute()
-
-	sendReq := &lnrpc.SendToRouteRequest{
+	sendReq := &routerrpc.SendToRouteRequest{
 		PaymentHash: resp.RHash,
 		Route:       routes.Routes[0],
 	}
-	err := alicePayStream.Send(sendReq)
-	require.NoError(ht, err, "unable to send payment")
-
-	// We expect this payment to fail, and that the min_htlc value is
-	// communicated back to us, since the attempted HTLC value was too low.
-	sendResp, err := ht.ReceiveSendToRouteUpdate(alicePayStream)
-	require.NoError(ht, err, "unable to receive payment stream")
-
-	// Expected as part of the error message.
-	substrs := []string{
-		"AmountBelowMinimum",
-		"HtlcMinimumMsat: (lnwire.MilliSatoshi) 5000 mSAT",
-	}
-	for _, s := range substrs {
-		require.Contains(ht, sendResp.PaymentError, s)
-	}
+	aliceHTLCAttempt := alice.RPC.SendToRouteV2(sendReq)
+	require.NotNil(ht, aliceHTLCAttempt.Failure)
 
 	// Make sure sending using the original value succeeds.
 	payAmt = btcutil.Amount(5)
@@ -215,17 +198,12 @@ func testUpdateChannelPolicy(ht *lntest.HarnessTest) {
 		TotalAmtMsat: amtMSat,
 	}
 
-	sendReq = &lnrpc.SendToRouteRequest{
+	sendReq = &routerrpc.SendToRouteRequest{
 		PaymentHash: resp.RHash,
 		Route:       route,
 	}
-
-	err = alicePayStream.Send(sendReq)
-	require.NoError(ht, err, "unable to send payment")
-
-	sendResp, err = ht.ReceiveSendToRouteUpdate(alicePayStream)
-	require.NoError(ht, err, "unable to receive payment stream")
-	require.Empty(ht, sendResp.PaymentError, "expected payment to succeed")
+	aliceHTLCAttempt = alice.RPC.SendToRouteV2(sendReq)
+	require.Nil(ht, aliceHTLCAttempt.Failure, "received payment error")
 
 	// With our little cluster set up, we'll update the fees and the max
 	// htlc size for the Bob side of the Alice->Bob channel, and make sure

itest/lnd_routing_test.go

@@ -22,34 +22,16 @@ import (
 type singleHopSendToRouteCase struct {
 	name string
 
-	// streaming tests streaming SendToRoute if true, otherwise tests
-	// synchronous SenToRoute.
-	streaming bool
-
 	// routerrpc submits the request to the routerrpc subserver if true,
 	// otherwise submits to the main rpc server.
 	routerrpc bool
 }
 
 var singleHopSendToRouteCases = []singleHopSendToRouteCase{
-	{
-		name: "regular main sync",
-	},
-	{
-		name:      "regular main stream",
-		streaming: true,
-	},
 	{
 		name:      "regular routerrpc sync",
 		routerrpc: true,
 	},
-	{
-		name: "mpp main sync",
-	},
-	{
-		name:      "mpp main stream",
-		streaming: true,
-	},
 	{
 		name:      "mpp routerrpc sync",
 		routerrpc: true,
@@ -144,43 +126,7 @@ func testSingleHopSendToRouteCase(ht *lntest.HarnessTest,
 	}
 
 	// Construct closures for each of the payment types covered:
-	//  - main rpc server sync
-	//  - main rpc server streaming
 	//  - routerrpc server sync
-	sendToRouteSync := func() {
-		for i, rHash := range rHashes {
-			setMPPFields(i)
-
-			sendReq := &lnrpc.SendToRouteRequest{
-				PaymentHash: rHash,
-				Route:       r,
-			}
-			resp := carol.RPC.SendToRouteSync(sendReq)
-			require.Emptyf(ht, resp.PaymentError,
-				"received payment error from %s: %v",
-				carol.Name(), resp.PaymentError)
-		}
-	}
-	sendToRouteStream := func() {
-		alicePayStream := carol.RPC.SendToRoute()
-
-		for i, rHash := range rHashes {
-			setMPPFields(i)
-
-			sendReq := &lnrpc.SendToRouteRequest{
-				PaymentHash: rHash,
-				Route:       routes.Routes[0],
-			}
-			err := alicePayStream.Send(sendReq)
-			require.NoError(ht, err, "unable to send payment")
-
-			resp, err := ht.ReceiveSendToRouteUpdate(alicePayStream)
-			require.NoError(ht, err, "unable to receive stream")
-			require.Emptyf(ht, resp.PaymentError,
-				"received payment error from %s: %v",
-				carol.Name(), resp.PaymentError)
-		}
-	}
 	sendToRouteRouterRPC := func() {
 		for i, rHash := range rHashes {
 			setMPPFields(i)
@@ -196,18 +142,9 @@ func testSingleHopSendToRouteCase(ht *lntest.HarnessTest,
 	}
 
 	// Using Carol as the node as the source, send the payments
-	// synchronously via the routerrpc's SendToRoute, or via the main RPC
-	// server's SendToRoute streaming or sync calls.
-	switch {
-	case !test.routerrpc && test.streaming:
-		sendToRouteStream()
-	case !test.routerrpc && !test.streaming:
-		sendToRouteSync()
-	case test.routerrpc && !test.streaming:
+	// synchronously via the routerrpc's SendToRoute.
+	if test.routerrpc {
 		sendToRouteRouterRPC()
-	default:
-		require.Fail(ht, "routerrpc does not support "+
-			"streaming send_to_route")
 	}
 
 	// Verify that the payment's from Carol's PoV have the correct payment
@@ -457,22 +394,12 @@ func testSendToRouteErrorPropagation(ht *lntest.HarnessTest) {
 	resp := bob.RPC.AddInvoice(invoice)
 	rHash := resp.RHash
 
-	// Using Alice as the source, pay to the invoice from Bob.
-	alicePayStream := alice.RPC.SendToRoute()
-
-	sendReq := &lnrpc.SendToRouteRequest{
+	sendReq := &routerrpc.SendToRouteRequest{
 		PaymentHash: rHash,
 		Route:       fakeRoute.Routes[0],
 	}
-	err := alicePayStream.Send(sendReq)
-	require.NoError(ht, err, "unable to send payment")
-
-	// At this place we should get an rpc error with notification
-	// that edge is not found on hop(0)
-	event, err := ht.ReceiveSendToRouteUpdate(alicePayStream)
-	require.NoError(ht, err, "payment stream has been closed but fake "+
-		"route has consumed")
-	require.Contains(ht, event.PaymentError, "UnknownNextPeer")
+	aliceHTLCAttempt := alice.RPC.SendToRouteV2(sendReq)
+	require.NotNil(ht, aliceHTLCAttempt.Failure)
 
 	ht.CloseChannel(alice, chanPointAlice)
 }

lnrpc/lightning.proto

@@ -255,42 +255,6 @@ service Lightning {
     */
     rpc AbandonChannel (AbandonChannelRequest) returns (AbandonChannelResponse);
 
-    /* lncli: `sendpayment`
-    Deprecated, use routerrpc.SendPaymentV2. SendPayment dispatches a
-    bi-directional streaming RPC for sending payments through the Lightning
-    Network. A single RPC invocation creates a persistent bi-directional
-    stream allowing clients to rapidly send payments through the Lightning
-    Network with a single persistent connection.
-    */
-    rpc SendPayment (stream SendRequest) returns (stream SendResponse) {
-        option deprecated = true;
-    }
-
-    /*
-    SendPaymentSync is the synchronous non-streaming version of SendPayment.
-    This RPC is intended to be consumed by clients of the REST proxy.
-    Additionally, this RPC expects the destination's public key and the payment
-    hash (if any) to be encoded as hex strings.
-    */
-    rpc SendPaymentSync (SendRequest) returns (SendResponse);
-
-    /* lncli: `sendtoroute`
-    Deprecated, use routerrpc.SendToRouteV2. SendToRoute is a bi-directional
-    streaming RPC for sending payment through the Lightning Network. This
-    method differs from SendPayment in that it allows users to specify a full
-    route manually. This can be used for things like rebalancing, and atomic
-    swaps.
-    */
-    rpc SendToRoute (stream SendToRouteRequest) returns (stream SendResponse) {
-        option deprecated = true;
-    }
-
-    /*
-    SendToRouteSync is a synchronous version of SendToRoute. It Will block
-    until the payment either fails or succeeds.
-    */
-    rpc SendToRouteSync (SendToRouteRequest) returns (SendResponse);
-
     /* lncli: `addinvoice`
     AddInvoice attempts to add a new invoice to the invoice database. Any
     duplicated invoices are rejected, therefore all invoices *must* have a

lntest/rpc/lnd.go

@@ -487,30 +487,6 @@ func (h *HarnessRPC) QueryRoutes(
 
 type SendToRouteClient lnrpc.Lightning_SendToRouteClient
 
-// SendToRoute makes a RPC call to SendToRoute and asserts.
-func (h *HarnessRPC) SendToRoute() SendToRouteClient {
-	// SendToRoute needs to have the context alive for the entire test case
-	// as the returned client will be used for send and receive payment
-	// stream. Thus we use runCtx here instead of a timeout context.
-	client, err := h.LN.SendToRoute(h.runCtx)
-	h.NoError(err, "SendToRoute")
-
-	return client
-}
-
-// SendToRouteSync makes a RPC call to SendToRouteSync and asserts.
-func (h *HarnessRPC) SendToRouteSync(
-	req *lnrpc.SendToRouteRequest) *lnrpc.SendResponse {
-
-	ctxt, cancel := context.WithTimeout(h.runCtx, DefaultTimeout)
-	defer cancel()
-
-	resp, err := h.LN.SendToRouteSync(ctxt, req)
-	h.NoError(err, "SendToRouteSync")
-
-	return resp
-}
-
 // UpdateChannelPolicy makes a RPC call to UpdateChannelPolicy and asserts.
 func (h *HarnessRPC) UpdateChannelPolicy(
 	req *lnrpc.PolicyUpdateRequest) *lnrpc.PolicyUpdateResponse {