(CWC-670) Add check for shell instantiation (#43)

* Add check for shell instantiation

We want to catch the situation where the shell isn't instantiated and throw that as a keysplitting error.

* update version file

Author: lgmugnier

VERSION

@@ -1 +1 @@
-3.0.732.17
+3.0.732.18

agent/keysplitting/contracts/model.go

@@ -131,4 +131,5 @@ const (
 	ChannelClosed                KeysplittingErrorType = "ChannelClosed"
 	OutdatedHPointer             KeysplittingErrorType = "OutdatedHPointer"
 	BZECertExpiredInitialIdToken KeysplittingErrorType = "BZECertExpiredInitialIdToken"
+	HandlerNotReady              KeysplittingErrorType = "HandlerNotReady"
 )

agent/session/plugins/interactivecommands/interactivecommands.go

@@ -193,7 +193,13 @@ func (p *InteractiveCommandsPlugin) forwardMessage(log log.T, streamDataMessage
 			Payload:     []byte(payload.Payload), // a string for Output or a json {cols: x, rows: y} for Size
 			PayloadType: uint32(payloadtype),     // either Output or Size
 		}
-		return p.shell.InputStreamMessageHandler(log, agentMessage)
+
+		if p.shell.Ready() {
+			return p.shell.InputStreamMessageHandler(log, agentMessage)
+		} else {
+			message := "Shell not yet ready for incoming messages"
+			return p.ksHelper.BuildError(message, kysplContracts.HandlerNotReady)
+		}
 	} else {
 		message := fmt.Sprintf("[Keysplitting] Keysplitting Handshake is required to communicate with shell")
 		return p.ksHelper.BuildError(message, kysplContracts.ChannelClosed)

agent/session/shell/shell.go

@@ -72,6 +72,11 @@ type logger struct {
 type IShellPlugin interface {
 	Execute(config agentContracts.Configuration, cancelFlag task.CancelFlag, output iohandler.IOHandler, dataChannel datachannel.IDataChannel, shellProps mgsContracts.ShellProperties)
 	InputStreamMessageHandler(log log.T, streamDataMessage mgsContracts.AgentMessage) error
+	Ready() bool
+}
+
+func (p *ShellPlugin) Ready() bool {
+	return !(p.stdin == nil || p.stdout == nil)
 }
 
 // NewPlugin returns a new instance of the Shell Plugin