check recv size

adafruit_wiznet5k/adafruit_wiznet5k.py

@@ -175,6 +175,7 @@ def __init__(
         self.mac_address = mac
         self._src_port = 0
         self._dns = 0
+
         # Set DHCP
         if is_dhcp:
             ret = self.set_dhcp(hostname, dhcp_timeout)
@@ -190,6 +191,17 @@ def set_dhcp(self, hostname=None, response_timeout=3):
         """
         if self._debug:
             print("* Initializing DHCP")
+
+        # First, wait link status is on
+        # to avoid the code during DHCP - assert self.link_status, "Ethernet cable disconnected!"
+        start_time = time.monotonic()
+        while True:
+            if self.link_status or ((time.monotonic() - start_time) > 5) :
+                break
+            time.sleep(1)
+            if self._debug:
+                print("My Link is:", self.link_status)
+
         self._src_port = 68
         # Return IP assigned by DHCP
         _dhcp_client = dhcp.DHCP(

adafruit_wiznet5k/adafruit_wiznet5k_dhcp.py

@@ -127,6 +127,10 @@ def send_dhcp_message(self, state, time_elapsed):
         :param float time_elapsed: Number of seconds elapsed since renewal.
 
         """
+        # before making send packet, shoule init _BUFF. 
+        # if not, DHCP sometimes fails, wrong padding, garbage bytes, ...
+        _BUFF[:] = b'\x00' * len(_BUFF)
+
         # OP
         _BUFF[0] = DHCP_BOOT_REQUEST
         # HTYPE
@@ -361,18 +365,15 @@ def request_dhcp_lease(
                     print("* DHCP: Parsing OFFER")
                 msg_type, xid = self.parse_dhcp_response(self._response_timeout)
                 if msg_type == DHCP_OFFER:
-                    # use the _transaction_id the offer returned,
-                    # rather than the current one
-                    self._transaction_id = self._transaction_id.from_bytes(xid, "l")
                     if self._debug:
-                        print("* DHCP: Request")
+                        print("* DHCP: Request", xid)
                     self.send_dhcp_message(
                         DHCP_REQUEST, ((time.monotonic() - start_time) / 1000)
                     )
                     self._dhcp_state = STATE_DHCP_REQUEST
                 else:
                     print("* Received DHCP Message is not OFFER")
-            elif STATE_DHCP_REQUEST:
+            elif self._dhcp_state == STATE_DHCP_REQUEST:
                 if self._debug:
                     print("* DHCP: Parsing ACK")
                 msg_type, xid = self.parse_dhcp_response(self._response_timeout)

examples/wiznet5k_simpleserver.py

@@ -31,6 +31,8 @@
 while True:
     conn, addr = server.accept()  # Wait for a connection from a client.
     with conn:
-        data = conn.recv()
-        print(data)
-        conn.send(data)  # Echo message back to client
+        while True:
+            data = conn.recv() 
+            if data: # Wait for receiving data
+                print(data)
+                conn.send(data)  # Echo message back to client