From 8540a7f088e7e44c931a597e4d961d2e801072bd Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Sat, 10 Nov 2018 16:03:40 +0100
Subject: [PATCH] rpc, signer: implement jsonrpc2.0 notifications
 (responseless)

---
 rpc/client.go          | 36 ++++++++++++++++++++++++++++++++++++
 rpc/http.go            |  6 ++++++
 signer/core/stdioui.go | 19 ++++++++++++++-----
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/rpc/client.go b/rpc/client.go
index 6254c95ffd..a7fe0a181d 100644
--- a/rpc/client.go
+++ b/rpc/client.go
@@ -245,6 +245,28 @@ func (c *Client) Call(result interface{}, method string, args ...interface{}) er
 	return c.CallContext(ctx, result, method, args...)
 }
 
+// Notify sends a JSON-RPC notification with the given arguments, and does not wait for a response,
+// effectively ignoring any responses sent
+//
+// https://www.jsonrpc.org/specification#request_object:
+// A Notification is a Request object without an "id" member.
+// A Request object that is a Notification signifies the Client's lack of interest in the
+// corresponding Response object, and as such no Response object needs to be returned to the client.
+// The Server MUST NOT reply to a Notification, including those that are within a batch request.
+func (c *Client) Notify(method string, args ...interface{}) error {
+	ctx := context.Background()
+	msg, err := c.newNotification(method, args...)
+	if err != nil {
+		return err
+	}
+	if c.isHTTP {
+		err = c.sendHTTP(ctx, nil, msg)
+	} else {
+		err = c.send(ctx, nil, msg)
+	}
+	return err
+}
+
 // CallContext performs a JSON-RPC call with the given arguments. If the context is
 // canceled before the call has successfully returned, CallContext returns immediately.
 //
@@ -416,9 +438,23 @@ func (c *Client) newMessage(method string, paramsIn ...interface{}) (*jsonrpcMes
 	return &jsonrpcMessage{Version: "2.0", ID: c.nextID(), Method: method, Params: params}, nil
 }
 
+func (c *Client) newNotification(method string, paramsIn ...interface{}) (*jsonrpcMessage, error) {
+	params, err := json.Marshal(paramsIn)
+	if err != nil {
+		return nil, err
+	}
+	return &jsonrpcMessage{Version: "2.0", Method: method, Params: params}, nil
+}
+
 // send registers op with the dispatch loop, then sends msg on the connection.
 // if sending fails, op is deregistered.
 func (c *Client) send(ctx context.Context, op *requestOp, msg interface{}) error {
+	if jsonrequest, ok := msg.(jsonrpcMessage); ok {
+		if jsonrequest.isNotification() {
+			// If we send a json-rpc notification, we expect no response
+			return c.write(ctx, msg)
+		}
+	}
 	select {
 	case c.requestOp <- op:
 		log.Trace("", "msg", log.Lazy{Fn: func() string {
diff --git a/rpc/http.go b/rpc/http.go
index af79858e2b..f00a7e5a3c 100644
--- a/rpc/http.go
+++ b/rpc/http.go
@@ -136,6 +136,12 @@ func (c *Client) sendHTTP(ctx context.Context, op *requestOp, msg interface{}) e
 		}
 		return err
 	}
+	if jsonrequest, ok := msg.(jsonrpcMessage); ok {
+		if jsonrequest.isNotification() {
+			// If we send a json-rpc notification, we expect no response
+			return nil
+		}
+	}
 	var respmsg jsonrpcMessage
 	if err := json.NewDecoder(respBody).Decode(&respmsg); err != nil {
 		return err
diff --git a/signer/core/stdioui.go b/signer/core/stdioui.go
index 64032386fc..4445565186 100644
--- a/signer/core/stdioui.go
+++ b/signer/core/stdioui.go
@@ -49,6 +49,15 @@ func (ui *StdIOUI) dispatch(serviceMethod string, args interface{}, reply interf
 	return err
 }
 
+// notify sends a request over the stdio, and does not listen for a response
+func (ui *StdIOUI) notify(serviceMethod string, args interface{}) error {
+	err := ui.client.Notify(serviceMethod, args)
+	if err != nil {
+		log.Info("Error", "exc", err.Error())
+	}
+	return err
+}
+
 func (ui *StdIOUI) ApproveTx(request *SignTxRequest) (SignTxResponse, error) {
 	var result SignTxResponse
 	err := ui.dispatch("ApproveTx", request, &result)
@@ -86,34 +95,34 @@ func (ui *StdIOUI) ApproveNewAccount(request *NewAccountRequest) (NewAccountResp
 }
 
 func (ui *StdIOUI) ShowError(message string) {
-	err := ui.dispatch("ShowError", &Message{message}, nil)
+	err := ui.notify("ShowError", &Message{message})
 	if err != nil {
 		log.Info("Error calling 'ShowError'", "exc", err.Error(), "msg", message)
 	}
 }
 
 func (ui *StdIOUI) ShowInfo(message string) {
-	err := ui.dispatch("ShowInfo", Message{message}, nil)
+	err := ui.notify("ShowInfo", Message{message})
 	if err != nil {
 		log.Info("Error calling 'ShowInfo'", "exc", err.Error(), "msg", message)
 	}
 }
 func (ui *StdIOUI) OnApprovedTx(tx ethapi.SignTransactionResult) {
-	err := ui.dispatch("OnApprovedTx", tx, nil)
+	err := ui.notify("OnApprovedTx", tx)
 	if err != nil {
 		log.Info("Error calling 'OnApprovedTx'", "exc", err.Error(), "tx", tx)
 	}
 }
 
 func (ui *StdIOUI) OnSignerStartup(info StartupInfo) {
-	err := ui.dispatch("OnSignerStartup", info, nil)
+	err := ui.notify("OnSignerStartup", info)
 	if err != nil {
 		log.Info("Error calling 'OnSignerStartup'", "exc", err.Error(), "info", info)
 	}
 }
 func (ui *StdIOUI) OnInputRequired(info UserInputRequest) (UserInputResponse, error) {
 	var result UserInputResponse
-	err := ui.dispatch("OnInputRequired", info, &result)
+	err := ui.notify("OnInputRequired", info)
 	if err != nil {
 		log.Info("Error calling 'OnInputRequired'", "exc", err.Error(), "info", info)
 	}