rpc: proper error code for GetChanInfo

When a channel edge is not found, return `NotFound` instead of the
generic `Unknown` error code.

Author: torkelrogstad

docs/release-notes/release-notes-0.19.0.md

@@ -131,6 +131,9 @@ when running LND with an aux component injected (custom channels).
 * [Fix a bug](https://github.com/lightningnetwork/lnd/pull/9798) that could
   result in a new topology client missing a channel-close notifications. 
 
+* [Fix a bug](https://github.com/lightningnetwork/lnd/pull/9810) where the
+  `GetChanInfo` RPC returned a bad status code for unknown channel edges. 
+
 # New Features
 
 * Add support for [archiving channel backup](https://github.com/lightningnetwork/lnd/pull/9232)

itest/list_on_test.go

@@ -563,6 +563,10 @@ var allTestCases = []*lntest.TestCase{
 		Name:     "query blinded route",
 		TestFunc: testQueryBlindedRoutes,
 	},
+	{
+		Name:     "query not-found channel info",
+		TestFunc: testGetChannelInfoNotFound,
+	},
 	{
 		Name:     "route blinding invoices",
 		TestFunc: testBlindedRouteInvoices,

itest/lnd_channel_graph_test.go

@@ -1,6 +1,7 @@
 package itest
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"testing"
@@ -15,7 +16,10 @@ import (
 	"github.com/lightningnetwork/lnd/lntest/node"
 	"github.com/lightningnetwork/lnd/lntest/wait"
 	"github.com/lightningnetwork/lnd/lnwire"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 // testUpdateChanStatus checks that calls to the UpdateChanStatus RPC update
@@ -420,6 +424,22 @@ func testNodeAnnouncement(ht *lntest.HarnessTest) {
 	assertAddrs(nodeUpdate.Addresses, advertisedAddrs...)
 }
 
+func testGetChannelInfoNotFound(ht *lntest.HarnessTest) {
+	ctx, cancel := context.WithTimeout(ht.Context(), lntest.DefaultTimeout)
+	defer cancel()
+
+	alice := ht.NewNode("Alice", nil)
+	_, err := alice.RPC.LN.GetChanInfo(ctx, &lnrpc.ChanInfoRequest{
+		ChanId: 949807622323240961,
+	})
+
+	ht.Logf("err: %s", err)
+	assert.Equal(
+		ht, codes.NotFound.String(), status.Code(err).String(),
+		"unknown channels should return a proper status code",
+	)
+}
+
 // testUpdateNodeAnnouncement ensures that the RPC endpoint validates
 // the requests correctly and that the new node announcement is broadcast
 // with the right information after updating our node.

lntest/rpc/harness_rpc.go

@@ -84,6 +84,11 @@ func NewHarnessRPC(ctxt context.Context, t *testing.T, c *grpc.ClientConn,
 	return h
 }
 
+// Context returns the context of the RPC harness.
+func (h *HarnessRPC) Context() context.Context {
+	return h.runCtx
+}
+
 // MakeOutpoint returns the outpoint of the channel's funding transaction.
 func (h *HarnessRPC) MakeOutpoint(cp *lnrpc.ChannelPoint) wire.OutPoint {
 	fundingTxID, err := lnrpc.GetChanPointFundingTxid(cp)

rpcserver.go

@@ -6913,7 +6913,10 @@ func (r *rpcServer) GetChanInfo(_ context.Context,
 	default:
 		return nil, fmt.Errorf("specify either chan_id or chan_point")
 	}
-	if err != nil {
+	switch {
+	case errors.Is(err, graphdb.ErrEdgeNotFound):
+		return nil, status.Error(codes.NotFound, err.Error())
+	case err != nil:
 		return nil, err
 	}