lnd: remove deprecated endpoints `sendpayment` and `sendtoroute`

[yyforyongyu]

The endpoints sendpayment and sendtoroute have been deprecated more than 3 years(#4147), and now should be safe to remove them,

lnd/lnrpc/lightning.proto

Lines 265 to 267 in e02fd39

	rpc SendPayment (stream SendRequest) returns (stream SendResponse) {
	option deprecated = true;
	}

lnd/lnrpc/lightning.proto

Lines 284 to 286 in e02fd39

	rpc SendToRoute (stream SendToRouteRequest) returns (stream SendResponse) {
	option deprecated = true;
	}

To properly remove them:

1. update the test framework by removing SendToRoute and replace all the old calls with the newer SendToRouteV2.
2. remove the endpoints, which includes rpcserver.go, lightning.proto and other unit test files.

[sidkhuntia]

Hey, I would like to work on it. Can you help me get started, I am kinda new to Go.

[yyforyongyu]

@sidkhuntia check the contribution guidelines.

[daviogg]

@yyforyongyu also need to remove SendToRouteSync and SendPaymentSync?

[yyforyongyu]

@daviogg yep

[mohamedawnallah]

Hey, @daviogg @yyforyongyu! I'm excited to contribute to lnd and have reviewed the contribution guidelines. As a first-timer, I might have some basic questions. Thanks in advance for your patience!

Questions:

In itest/lnd_routing_test.go and itest/lnd_channel_policy_test.go, unsure how to replace alice.RPC.SendToRoute() with alice.RPC.SendToRouteV2(sendReq). The former returns SendToRouteClient, while the latter returns HTLCAttempt. Unsure about conversion (if needed) from HTLCAttempt to SendToRouteClient because later ReceiveSendToRouteUpdate is called with an input of type SendToRouteClient that's returned from alice.RPC.SendToRoute() .

How I'm gonna address this issue (apart from the previous question):

1. Update lightning.proto:

   • Remove SendPayment, SendPaymentSync, SendToRoute, and SendToRouteSync from lightning.proto.

2. Adjust MainRPCServerPermissions:

   • In rpcserver.go, remove permissions associated with the deprecated endpoints:

     func MainRPCServerPermissions() map[string][]bakery.Op {
         // Existing permissions...
	"/lnrpc.Lightning/SendPayment": {{
		Entity: "offchain",
		Action: "write",
	}},
	"/lnrpc.Lightning/SendPaymentSync": {{
		Entity: "offchain",
		Action: "write",
	}},
	"/lnrpc.Lightning/SendToRoute": {{
		Entity: "offchain",
		Action: "write",
	}},
	"/lnrpc.Lightning/SendToRouteSync": {{
		Entity: "offchain",
		Action: "write",
	}},
     }

3. Update rpcserver.go:

   • Remove the following functions:
     • SendPayment
     • SendToRoute
     • unmarshallSendToRouteRequest
     • SendPaymentSync
     • SendToRouteSync

4. Adjust lntest/rpc/lnd.go:

   • Remove SendToRoute and SendToRouteSync from lntest/rpc/lnd.go.

5. Update itest/lnd_routing_test.go:

   • Remove sendToRouteSync and sendToRouteStream.
   • Update the switch cases to if statements:

     if test.routerrpc && !test.streaming {
         sendToRouteRouterRPC()
     } else if test.routerrpc && test.streaming {
         require.Fail(ht, "routerrpc does not support streaming send_to_route")
     }

6. Validation:

   • To ensure stability, running test cases via make check to verify all tests pass and to avoid any potential codebase regressions.

Please let me know if anything I'm missing, Thanks 🙏

[yyforyongyu]

@mohamedawnallah Thank you for taking a detailed look at this issue🙏

unsure how to replace alice.RPC.SendToRoute() with alice.RPC.SendToRouteV2(sendReq). The former returns SendToRouteClient

You can view SendToRouteV2 as a combination of two calls, stream := SendToRoute() and stream.Send(req), and there's no need to assert updates in ReceiveSendToRouteUpdate anymore.

How I'm gonna address this issue (apart from the previous question):

This is really a nice breakup of the task! Feel free to implement it, and, just to be extra safe, I think we can aim at finishing it in 0.19.0, and give a notice about the incoming removal in 0.18 first.

[mohamedawnallah]

Thank you, @yyforyongyu, for unblocking me regarding the removal of ReceiveSendToRouteUpdate. I've just submitted PR #8348 for this issue, which addresses the removal of those deprecated endpoints and updates the release notes in preparation for the 0.19.0 release. I would appreciate any feedback. Thanks! 🙏