Remove extraneous empty struct returns from RPC interface

go/cmd/entrypoint/host.go

@@ -116,8 +116,7 @@ var subCmdHostRemove = subCmd{
 			return errors.New("--hostname is required")
 		}
 
-		_, err := ctx.daemonRPC.RemoveHost(ctx, hostName.V)
+		if err := ctx.daemonRPC.RemoveHost(ctx, hostName.V); err != nil {
-		if err != nil {
 			return fmt.Errorf("calling RemoveHost: %w", err)
 		}
 

go/cmd/entrypoint/network.go

@@ -51,7 +51,7 @@ var subCmdNetworkCreate = subCmd{
 			return errors.New("--name, --domain, --ip-net, and --hostname are required")
 		}
 
-		_, err := ctx.daemonRPC.CreateNetwork(
+		err := ctx.daemonRPC.CreateNetwork(
 			ctx, *name, *domain, ipNet.V, hostName.V,
 		)
 		if err != nil {
@@ -88,8 +88,7 @@ var subCmdNetworkJoin = subCmd{
 			)
 		}
 
-		_, err := ctx.daemonRPC.JoinNetwork(ctx, newBootstrap)
+		return ctx.daemonRPC.JoinNetwork(ctx, newBootstrap)
-		return err
 	},
 }
 

go/daemon/client.go

@@ -44,11 +44,10 @@ func (c *rpcClient) CreateNebulaCertificate(ctx context.Context, hostName nebula
 	return
 }
 
-func (c *rpcClient) CreateNetwork(ctx context.Context, name string, domain string, ipNet nebula.IPNet, hostName nebula.HostName) (st1 struct {
+func (c *rpcClient) CreateNetwork(ctx context.Context, name string, domain string, ipNet nebula.IPNet, hostName nebula.HostName) (err error) {
-}, err error) {
 	err = c.client.Call(
 		ctx,
-		&st1,
+		nil,
 		"CreateNetwork",
 		name,
 		domain,
@@ -85,22 +84,20 @@ func (c *rpcClient) GetNebulaCAPublicCredentials(ctx context.Context) (c2 nebula
 	return
 }
 
-func (c *rpcClient) JoinNetwork(ctx context.Context, req JoiningBootstrap) (st1 struct {
+func (c *rpcClient) JoinNetwork(ctx context.Context, req JoiningBootstrap) (err error) {
-}, err error) {
 	err = c.client.Call(
 		ctx,
-		&st1,
+		nil,
 		"JoinNetwork",
 		req,
 	)
 	return
 }
 
-func (c *rpcClient) RemoveHost(ctx context.Context, hostName nebula.HostName) (st1 struct {
+func (c *rpcClient) RemoveHost(ctx context.Context, hostName nebula.HostName) (err error) {
-}, err error) {
 	err = c.client.Call(
 		ctx,
-		&st1,
+		nil,
 		"RemoveHost",
 		hostName,
 	)

go/daemon/jsonrpc2/client_gen.tpl

@@ -17,11 +17,21 @@ func {{.Interface.Name}}FromClient(client jsonrpc2.Client) {{.Interface.Name}} {
 {{range $method := .Interface.Methods}}
 func (c *{{$t}}) {{$method.Declaration}} {
     {{- $ctx := (index $method.Params 0).Name}}
-    {{- $rcv := (index $method.Results 0).Name}}
+
-    {{- $err := (index $method.Results 1).Name}}
+    {{- $rcv := ""}}
+    {{- $err := ""}}
+
+    {{- if (eq (len $method.Results) 1)}}
+    {{- $rcv = "nil" }}
+    {{- $err = (index $method.Results 0).Name}}
+    {{- else}}
+    {{- $rcv = printf "&%s" (index $method.Results 0).Name}}
+    {{- $err = (index $method.Results 1).Name}}
+    {{- end}}
+
     {{- $err}} = c.client.Call(
         {{$ctx}},
-        &{{$rcv}},
+        {{$rcv}},
         "{{$method.Name}}",
         {{- range $param := (slice $method.Params 1)}}
         {{$param.Name}},

go/daemon/jsonrpc2/dispatcher.go

@@ -49,15 +49,25 @@ func newMethodDispatchFunc(
 
 		var (
 			callResV   = method.Call(callVals)
-			resV     = callResV[0]
+			resV, errV reflect.Value
-			errV     = callResV[1]
 		)
 
-		if errV.IsNil() {
+		if len(callResV) == 1 {
+			errV = callResV[0]
+		} else {
+			resV = callResV[0]
+			errV = callResV[1]
+		}
+
+		if !errV.IsNil() {
+			return nil, errV.Interface().(error)
+		}
+
+		if resV.IsValid() {
 			return resV.Interface(), nil
 		}
 
-		return nil, errV.Interface().(error)
+		return nil, nil
 	}
 }
 
@@ -96,8 +106,9 @@ func NewDispatchHandler(i any) Handler {
 		if !method.IsExported() ||
 			methodT.NumIn() < 1 ||
 			methodT.In(0) != ctxT ||
-			methodT.NumOut() != 2 ||
+			(methodT.NumOut() == 1 && methodT.Out(0) != errT) ||
-			methodT.Out(1) != errT {
+			(methodT.NumOut() == 2 && methodT.Out(1) != errT) ||
+			methodT.NumOut() > 2 {
 			continue
 		}
 

go/daemon/jsonrpc2/jsonrpc2_test.go

@@ -36,12 +36,16 @@ func (dividerImpl) Divide2(ctx context.Context, top, bottom int) (int, error) {
 	return top / bottom, nil
 }
 
-func (i dividerImpl) Noop(ctx context.Context) (int, error) {
+func (i dividerImpl) Divide(ctx context.Context, p DivideParams) (int, error) {
+	return i.Divide2(ctx, p.Top, p.Bottom)
+}
+
+func (i dividerImpl) One(ctx context.Context) (int, error) {
 	return 1, nil
 }
 
-func (i dividerImpl) Divide(ctx context.Context, p DivideParams) (int, error) {
+func (i dividerImpl) Noop(ctx context.Context) error {
-	return i.Divide2(ctx, p.Top, p.Bottom)
+	return nil
 }
 
 func (dividerImpl) Hidden(ctx context.Context, p struct{}) (int, error) {
@@ -49,9 +53,10 @@ func (dividerImpl) Hidden(ctx context.Context, p struct{}) (int, error) {
 }
 
 type divider interface {
-	Noop(ctx context.Context) (int, error)
 	Divide2(ctx context.Context, top, bottom int) (int, error)
 	Divide(ctx context.Context, p DivideParams) (int, error)
+	One(ctx context.Context) (int, error)
+	Noop(ctx context.Context) error
 }
 
 var testHandler = func() Handler {
@@ -104,7 +109,7 @@ func testClient(t *testing.T, client Client) {
 
 	t.Run("success/no_params", func(t *testing.T) {
 		var res int
-		err := client.Call(ctx, &res, "Noop")
+		err := client.Call(ctx, &res, "One")
 		if err != nil {
 			t.Fatal(err)
 		} else if res != 1 {
@@ -112,6 +117,13 @@ func testClient(t *testing.T, client Client) {
 		}
 	})
 
+	t.Run("success/no_results", func(t *testing.T) {
+		err := client.Call(ctx, nil, "Noop")
+		if err != nil {
+			t.Fatal(err)
+		}
+	})
+
 	t.Run("err/application", func(t *testing.T) {
 		err := client.Call(ctx, nil, "Divide", DivideParams{})
 		if !errors.Is(err, ErrDivideByZero) {

go/daemon/rpc.go

@@ -45,16 +45,10 @@ type RPC interface {
 		domain string,
 		ipNet nebula.IPNet,
 		hostName nebula.HostName,
-	) (
+	) error
-		struct{}, error,
-	)
 
 	// JoinNetwork passes through to the Daemon method of the same name.
-	JoinNetwork(
+	JoinNetwork(ctx context.Context, req JoiningBootstrap) error
-		ctx context.Context, req JoiningBootstrap,
-	) (
-		struct{}, error,
-	)
 
 	// GetHosts returns all hosts known to the network, sorted by their name.
 	GetHosts(ctx context.Context) (GetHostsResult, error)
@@ -72,11 +66,7 @@ type RPC interface {
 	)
 
 	// RemoveHost passes the call through to the Daemon method of the same name.
-	RemoveHost(
+	RemoveHost(ctx context.Context, hostName nebula.HostName) error
-		ctx context.Context, hostName nebula.HostName,
-	) (
-		struct{}, error,
-	)
 
 	// CreateHost passes the call through to the Daemon method of the same name.
 	CreateHost(
@@ -111,20 +101,16 @@ func (r *rpcImpl) CreateNetwork(
 	domain string,
 	ipNet nebula.IPNet,
 	hostName nebula.HostName,
-) (
+) error {
-	struct{}, error,
+	return r.daemon.CreateNetwork(
-) {
-	return struct{}{}, r.daemon.CreateNetwork(
 		ctx, name, domain, ipNet, hostName,
 	)
 }
 
 func (r *rpcImpl) JoinNetwork(
 	ctx context.Context, req JoiningBootstrap,
-) (
+) error {
-	struct{}, error,
+	return r.daemon.JoinNetwork(ctx, req)
-) {
-	return struct{}{}, r.daemon.JoinNetwork(ctx, req)
 }
 
 func (r *rpcImpl) GetHosts(ctx context.Context) (GetHostsResult, error) {
@@ -166,10 +152,8 @@ func (r *rpcImpl) GetNebulaCAPublicCredentials(
 
 func (r *rpcImpl) RemoveHost(
 	ctx context.Context, hostName nebula.HostName,
-) (
+) error {
-	struct{}, error,
+	return r.daemon.RemoveHost(ctx, hostName)
-) {
-	return struct{}{}, r.daemon.RemoveHost(ctx, hostName)
 }
 
 func (r *rpcImpl) CreateHost(