Shows an error with usocket' datagram socket sending userial buffers on SBCL 1.2.1 Windows 8.1

udp-userial-test

;; using userial with usocket's datagram socket causes an intermittent error.

(ql:quickload "usocket")
(ql:quickload "userial")

(defun server-main ()
  (let ((socket (usocket:socket-connect nil 
					nil
					:protocol :datagram
					:element-type '(unsigned-byte 8)
					:local-host "127.0.0.1"
					:local-port 2448)))
    (unwind-protect
	 (multiple-value-bind (buffer size remote-host remote-port)
	     (usocket:socket-receive socket (make-array 32768 :element-type '(unsigned-byte 8) :fill-pointer t) nil)
	   (format t "received buffer from client~%")
	   (finish-output)
	   (loop 
	      (format t "sending data to client~%")
	      (finish-output)
	      (usocket:socket-send socket 
				   (userial:make-buffer)
				   32768
				   :host remote-host
				   :port remote-port)
	      (sleep 1)))
      (usocket:socket-close socket))))

(defun client-main ()
  (let ((socket (usocket:socket-connect "127.0.0.1" 
					2448
					:protocol :datagram
					:element-type '(unsigned-byte 8))))
    (unwind-protect
	 (progn
	   (format t "sending data to server~%")
	   (finish-output)
	   (usocket:socket-send socket (make-array 32768 :element-type '(unsigned-byte 8) :fill-pointer t) 32768)
	   (loop 
	      (usocket:socket-receive socket (make-array 32768 :element-type '(unsigned-byte 8) :fill-pointer t) nil)
	      (format t "received buffer from server~%")))
      (usocket:socket-close socket))))

;; To test for yourself you need two REPLs - one for the server and one for the client.
;; Load this file in both REPLs.

;; Run the server in the first REPL with (server-main)

;; Run the client in the second REPL with (client-main)

;;
;; After a short time (maybe 500 packets) the server crashes with the following error:
;;
;;Socket error in "sendto": 10014 (The system detected an invalid pointer address in attempting to use a pointer argument in a call.)
;;   [Condition of type SB-BSD-SOCKETS:SOCKET-ERROR]


;; Replace (userial:make-buffer) with a (make-array) will remove the error and will run all day.