Update simple_tcp_server_v1.go (#353)

all with go1.8

eBook/examples/chapter_15/simple_tcp_server_v1.go

@@ -23,10 +23,10 @@ func main() {
 		go connectionHandler(conn)
 	}
 }
-func initServer(hostAndPort string) *net.TCPListener {
+func initServer(hostAndPort string) net.Listener {
 	serverAddr, err := net.ResolveTCPAddr("tcp", hostAndPort)
 	checkError(err, "Resolving address:port failed: '"+hostAndPort+"'")
-	listener, err := net.Listen("tcp", serverAddr)
+	listener, err := net.Listen("tcp", serverAddr.String())
 	checkError(err, "ListenTCP: ")
 	println("Listening to: ", listener.Addr().String())
 	return listener
@@ -42,7 +42,7 @@ func connectionHandler(conn net.Conn) {
 		switch err {
 		case nil:
 			handleMsg(length, err, ibuf)
-		case syscall.Errno(0xb): // try again
+		case syscall.EAGAIN: // try again
 			continue
 		default:
 			goto DISCONNECT