Avoid crash when sending from inactive keyper

Previously keypers would crash, when trying to send a batch config to
shuttermint ahead of time, with the crash log

```
Error: remote error: checktx: not a keyper set member
remote error: checktx: not a keyper set member
```

With these changes, keypers will

a) check, if they are known to shuttermint, and therefore allowed to
send messages.

b) keep messages that failed to send in the outgoing message queue.

This is part of #465

Author: konradkonrad

rolling-shutter/keyper/fx/messagesender.go

@@ -74,9 +74,10 @@ type MessageSender interface {
 
 // RPCMessageSender signs messages and sends them via RPC to shuttermint.
 type RPCMessageSender struct {
-	rpcclient  client.Client
-	chainID    string
-	signingKey *ecdsa.PrivateKey
+	rpcclient     client.Client
+	chainID       string
+	signingKey    *ecdsa.PrivateKey
+	AllowedToSend bool
 }
 
 var _ MessageSender = &RPCMessageSender{}
@@ -93,14 +94,19 @@ var mockMessageSenderBufferSize = 0x10000
 // NewRPCMessageSender creates a new RPCMessageSender.
 func NewRPCMessageSender(cl client.Client, signingKey *ecdsa.PrivateKey) RPCMessageSender {
 	return RPCMessageSender{
-		rpcclient:  cl,
-		chainID:    "",
-		signingKey: signingKey,
+		rpcclient:     cl,
+		chainID:       "",
+		signingKey:    signingKey,
+		AllowedToSend: false,
 	}
 }
 
 // SendMessage signs the given shmsg.Message and sends the message to shuttermint.
 func (ms *RPCMessageSender) SendMessage(ctx context.Context, msg *shmsg.Message) error {
+	if !ms.AllowedToSend {
+		log.Info().Str("msg", msg.String()).Msg("not allowed to send")
+		return nil
+	}
 	if err := ms.maybeFetchChainID(ctx); err != nil {
 		return err
 	}

rolling-shutter/keyper/fx/send.go

@@ -31,7 +31,13 @@ func SendShutterMessages(
 		}
 		err = messageSender.SendMessage(ctx, msg)
 		if err != nil {
-			return err // XXX retry
+			if !isRetrieable(msg) {
+				log.Err(err).Str("msg", msg.String()).Msg("sending non-retrieable msg failed")
+				return err
+			} else {
+				log.Info().Str("msg", msg.String()).Msg("msg not accepted, will be retried")
+				return nil
+			}
 		}
 		log.Info().Int32("id", outgoing.ID).
 			Str("description", outgoing.Description).
@@ -42,3 +48,8 @@ func SendShutterMessages(
 		}
 	}
 }
+
+// isRetrieable is a no-op so far
+func isRetrieable(msg *shmsg.Message) bool {
+	return true
+}

rolling-shutter/keyper/keyper.go

@@ -358,7 +358,9 @@ func (kpr *KeyperCore) operateShuttermint(ctx context.Context, _ service.Runner)
 		if err != nil {
 			return err
 		}
-
+		if !kpr.messageSender.AllowedToSend {
+			allowSendIfInKeyperSet(ctx, database.New(kpr.dbpool), syncBlockNumber, kpr)
+		}
 		err = fx.SendShutterMessages(ctx, database.New(kpr.dbpool), &kpr.messageSender)
 		if err != nil {
 			return err
@@ -370,3 +372,18 @@ func (kpr *KeyperCore) operateShuttermint(ctx context.Context, _ service.Runner)
 		}
 	}
 }
+
+func allowSendIfInKeyperSet(ctx context.Context, queries *database.Queries, syncBlockNumber uint64, kpr *KeyperCore) {
+	count, err := queries.CountBatchConfigsInBlockRangeWithKeyper(ctx,
+		database.CountBatchConfigsInBlockRangeWithKeyperParams{
+			KeyperAddress: []string{kpr.config.GetAddress().String()},
+			StartBlock:    0,
+			EndBlock:      int64(syncBlockNumber),
+		})
+	if err != nil {
+		log.Err(err).Msg("could not query if in keyper set")
+	}
+	if count > 0 {
+		kpr.messageSender.AllowedToSend = true
+	}
+}