Wait for connect to finish sending all data

Goroutines created in connect, transfer data from a handler to telnet
client. However, as there's no synchronization between the goroutines
and the telnet server, there's a case where the server sends a prompt
before the goroutines finishsed all transmissions.

This fix assure that the telnet server waits until all data are sent to
the client, before sending a prompt.

telsh/telnet_handler.go

@@ -229,27 +229,35 @@ func (telnetHandler *ShellHandler) ServeTELNET(ctx telnet.Context, writer telnet
 
 //@TODO: Wire up the stdin, stdout, stderr of the handler.
 
+			var stdoutDone chan bool
 			if stdoutPipe, err := handler.StdoutPipe(); nil != err {
 //@TODO:                              
 			} else if nil == stdoutPipe {
 //@TODO:                              
 			} else {
-				connect(ctx, writer, stdoutPipe)
+				stdoutDone = connect(ctx, writer, stdoutPipe)
 			}
 
 
+			var stderrDone chan bool
 			if stderrPipe, err := handler.StderrPipe(); nil != err {
 //@TODO:                              
 			} else if nil == stderrPipe {
 //@TODO:                              
 			} else {
-				connect(ctx, writer, stderrPipe)
+				stderrDone = connect(ctx, writer, stderrPipe)
 			}
 
 
 			if err := handler.Run(); nil != err {
 //@TODO:                                    
 			}
+			if stdoutDone != nil {
+				<-stdoutDone
+			}
+			if stderrDone != nil {
+				<-stderrDone
+			}
 			line.Reset()
 			if _, err := oi.LongWrite(writer, promptBytes); nil != err {
 				return
@@ -270,10 +278,13 @@ func (telnetHandler *ShellHandler) ServeTELNET(ctx telnet.Context, writer telnet
 
 
 
-func connect(ctx telnet.Context, writer io.Writer, reader io.Reader) {
+func connect(ctx telnet.Context, writer io.Writer, reader io.Reader) chan bool {
 
 	logger := ctx.Logger()
 
+	// Create a buffer to avoid the goroutine to be blocked.
+	// The goroutine may leave whenever its job is done.
+	done := make(chan bool, 1)
 	go func(logger telnet.Logger){
 
 		var buffer [1]byte // Seems like the length of the buffer needs to be small, otherwise will have to wait for buffer to fill up.
@@ -293,5 +304,7 @@ func connect(ctx telnet.Context, writer io.Writer, reader io.Reader) {
 			oi.LongWrite(writer, p)
 			//logger.Tracef("Sent: %q.", p)
 		}
+		done <- true
 	}(logger)
+	return done
 }