adafruit · FoamyGuy · Mar 20, 2023 · Feb 16, 2023 · Feb 16, 2023 · Mar 20, 2023
diff --git a/adafruit_wiznet5k/adafruit_wiznet5k.py b/adafruit_wiznet5k/adafruit_wiznet5k.py
@@ -45,11 +45,13 @@
 
 from random import randint
 import time
+import gc
 from micropython import const
 
 from adafruit_bus_device.spi_device import SPIDevice
 import adafruit_wiznet5k.adafruit_wiznet5k_dhcp as dhcp
 import adafruit_wiznet5k.adafruit_wiznet5k_dns as dns
+from adafruit_wiznet5k.adafruit_wiznet5k_debug import debug_msg
 
 # Wiznet5k Registers
 _REG_MR = const(0x0000)  # Mode
@@ -144,6 +146,8 @@ class WIZNET5K:  # pylint: disable=too-many-public-methods, too-many-instance-at
     _UDP_MODE = const(0x02)
     _TLS_MODE = const(0x03)  # This is NOT currently implemented
 
+    _sockets_reserved = []
+
     # pylint: disable=too-many-arguments
     def __init__(
         self,
@@ -189,6 +193,13 @@ def __init__(
         self._ch_base_msb = 0
         if self._w5xxx_init() != 1:
             raise RuntimeError("Failed to initialize WIZnet module.")
+        if self._chip_type == "w5100s":
+            WIZNET5K._sockets_reserved = [False] * (_W5100_MAX_SOCK_NUM - 1)
+        elif self._chip_type == "w5500":
+            WIZNET5K._sockets_reserved = [False] * (_W5200_W5500_MAX_SOCK_NUM - 1)
+        else:
+            raise RuntimeError("Unrecognized chip type.")
+
         # Set MAC address
         self.mac_address = mac
         self.src_port = 0
@@ -722,26 +733,61 @@ def _send_socket_cmd(self, socket: int, cmd: int) -> None:
             if self._debug:
                 print("waiting for sncr to clear...")
 
-    def get_socket(self) -> int:
-        """Request, allocate and return a socket from the W5k chip.
+    def get_socket(self, *, reserve_socket=False) -> int:
+        """
+        Request, allocate and return a socket from the W5k chip.
+
+        Cycle through the sockets to find the first available one. If the called with
+        reserve_socket=True, update the list of reserved sockets (intended to be used with
+        socket.socket()). Note that reserved sockets must be released by calling
+        cancel_reservation() once they are no longer needed.
+
+        If all sockets are reserved, no sockets are available for DNS calls, etc. Therefore,
+        one socket cannot be reserved. Since socket 0 is the only socket that is capable of
+        operating in MacRAW mode, it is the non-reservable socket.
+
+        :param bool reserve_socket: Whether to reserve the socket.
 
-        Cycle through the sockets to find the first available one, if any.
+        :returns int: The first available socket.
 
-        :return int: The first available socket. Returns 0xFF if no sockets are free.
+        :raises RuntimeError: If no socket is available.
         """
-        if self._debug:
-            print("*** Get socket")
+        debug_msg("*** Get socket.", self._debug)
+        # Prefer socket zero for none reserved calls as it cannot be reserved.
+        if not reserve_socket and self.socket_status(0)[0] == SNSR_SOCK_CLOSED:
+            debug_msg("Allocated socket # 0", self._debug)
+            return 0
+        # Then check the other sockets.
 
-        sock = _SOCKET_INVALID
-        for _sock in range(self.max_sockets):
-            status = self.socket_status(_sock)[0]
-            if status == SNSR_SOCK_CLOSED:
-                sock = _sock
-                break
+        #  Call garbage collection to encourage socket.__del__() be called to on any
+        #  destroyed instances. Not at all guaranteed to work!
+        gc.collect()
+        debug_msg(
+            "Reserved sockets: {}".format(WIZNET5K._sockets_reserved), self._debug
+        )
 
-        if self._debug:
-            print("Allocated socket #{}".format(sock))
-        return sock
+        for socket_number, reserved in enumerate(WIZNET5K._sockets_reserved, start=1):
+            if (
+                not reserved
+                and self.socket_status(socket_number)[0] == SNSR_SOCK_CLOSED
+            ):
+                if reserve_socket:
+                    WIZNET5K._sockets_reserved[socket_number - 1] = True
+                    debug_msg(
+                        "Allocated socket # {}.".format(socket_number),
+                        self._debug,
+                    )
+                return socket_number
+        raise RuntimeError("Out of sockets.")
+
+    @staticmethod
+    def release_socket(socket_number):
+        """
+        Update the socket reservation list when a socket is no longer reserved.
+
+        :param int socket_number: The socket to release.
+        """
+        WIZNET5K._sockets_reserved[socket_number - 1] = False
 
     def socket_listen(
         self, socket_num: int, port: int, conn_mode: int = _SNMR_TCP

diff --git a/adafruit_wiznet5k/adafruit_wiznet5k_debug.py b/adafruit_wiznet5k/adafruit_wiznet5k_debug.py
@@ -0,0 +1,49 @@
+# SPDX-FileCopyrightText: 2023 Martin Stephens
+#
+# SPDX-License-Identifier: MIT
+
+"""Makes a debug message function available to all modules."""
+try:
+    from typing import TYPE_CHECKING, Union
+
+    if TYPE_CHECKING:
+        from adafruit_wiznet5k.adafruit_wiznet5k import WIZNET5K
+except ImportError:
+    pass
+
+import gc
+
+
+def debug_msg(
+    message: Union[Exception, str, bytes, bytearray], debugging: bool
+) -> None:
+    """
+    Helper function to print debugging messages. If the message is a bytes type
+    object, create a hexdump.
+
+    :param Union[Exception, str, bytes, bytearray] message: The message to print.
+    :param bool debugging: Only print if debugging is True.
+    """
+    if debugging:
+        if isinstance(message, (bytes, bytearray)):
+            message = _hexdump(message)
+        print(message)
+        del message
+        gc.collect()
+
+
+def _hexdump(src: bytes):
+    """
+    Create a 16 column hexdump of a bytes object.
+
+    :param bytes src: The bytes object to hexdump.
+
+    :returns str: The hexdump.
+    """
+    result = []
+    for i in range(0, len(src), 16):
+        chunk = src[i : i + 16]
+        hexa = " ".join(("{:02x}".format(x) for x in chunk))
+        text = "".join((chr(x) if 0x20 <= x < 0x7F else "." for x in chunk))
+        result.append("{:04x}   {:<48}   {}".format(i, hexa, text))
+    return "\n".join(result)
diff --git a/adafruit_wiznet5k/adafruit_wiznet5k_socket.py b/adafruit_wiznet5k/adafruit_wiznet5k_socket.py
@@ -232,14 +232,18 @@ def __init__(
         self._timeout = _default_socket_timeout
         self._listen_port = None
 
-        self._socknum = _the_interface.get_socket()
+        self._socknum = _the_interface.get_socket(reserve_socket=True)
         if self._socknum == _SOCKET_INVALID:
             raise RuntimeError("Failed to allocate socket.")
 
+    def __del__(self):
+        _the_interface.release_socket(self._socknum)
+
     def __enter__(self):
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb) -> None:
+        _the_interface.release_socket(self._socknum)
         if self._sock_type == SOCK_STREAM:
             self._disconnect()
             stamp = time.monotonic()
@@ -625,8 +629,9 @@ def close(self) -> None:
         Mark the socket closed. Once that happens, all future operations on the socket object
         will fail. The remote end will receive no more data.
         """
-        self._socket_closed = True
+        _the_interface.release_socket(self._socknum)
         _the_interface.socket_close(self._socknum)
+        self._socket_closed = True
 
     def _available(self) -> int:
         """