Fix for issue #108 - Make sure the buffer is large enough before every send

Author: dgnuff

adafruit_wiznet5k/adafruit_wiznet5k_dhcp.py

@@ -86,7 +86,8 @@
 _OPT_END = 255
 
 # Packet buffer
-_BUFF = bytearray(318)
+_BUFF_SIZE = const(318)
+_BUFF = bytearray(_BUFF_SIZE)
 
 
 class DHCP:
@@ -166,7 +167,7 @@ def send_dhcp_message(
         :param float time_elapsed: Number of seconds elapsed since DHCP process started
         :param bool renew: Set True for renew and rebind, defaults to False
         """
-        _BUFF[:] = b"\x00" * len(_BUFF)
+        _BUFF = bytearray(_BUFF_SIZE)
         # OP
         _BUFF[0] = _DHCP_BOOT_REQUEST
         # HTYPE