Refactored ARP related code.

.gitignore

@@ -1,2 +1,2 @@
-
 __pycache__/
+venv/

.vscode/settings.json

@@ -2,5 +2,8 @@
     "python.analysis.extraPaths": [
         "./pytcp"
     ],
-    "python.formatting.provider": "black"
+    "python.formatting.provider": "none",
+    "[python]": {
+        "editor.defaultFormatter": "ms-python.black-formatter"
+    }
 }

pytcp/config.py

@@ -73,22 +73,6 @@
 }
 LOG_DEBUG = False
 
-# Packet integrity sanity check, if enabled it protects the protocol parsers
-# from being exposed to malformed or malicious packets that could cause them
-# to crash during packet parsing. It progessively check appropriate length
-# fields and ensure they are set within sane boundaries. It also checks
-# packet's actual header/options/data lengths against above values and default
-# minimum/maximum lengths for given protocol. Also packet options (if any) are
-# checked in similar fashion to ensure they will not exploit or crash parser.
-PACKET_INTEGRITY_CHECK = True
-
-# Packet sanity check, if enabled it validates packet's fields to detect invalid
-# values or invalid combinations of values. For example in TCP/UDP it drops
-# packets with port set to 0, in TCP it drop packet with SYN and FIN flags set
-# simultaneously, for ICMPv6 it provides very detailed check of messages
-# integrity.
-PACKET_SANITY_CHECK = True
-
 # Drop IPv4 packets containing options - this seems to be widely adopted
 # security feature. Stack parses but doesn't support IPv4 options as they are
 # mostly useless anyway.
@@ -144,3 +128,6 @@
 # Native support for UDP Echo (used for packet flow unit testing only and should
 # always be disabled).
 UDP_ECHO_NATIVE_DISABLE = True
+
+# LRU cache size, used by packet parsers to cache parsed field values.
+LRU_CACHE_SIZE = 16

pytcp/lib/errors.py

@@ -0,0 +1,79 @@
+#!/usr/bin/env python3
+
+############################################################################
+#                                                                          #
+#  PyTCP - Python TCP/IP stack                                             #
+#  Copyright (C) 2020-present Sebastian Majewski                           #
+#                                                                          #
+#  This program is free software: you can redistribute it and/or modify    #
+#  it under the terms of the GNU General Public License as published by    #
+#  the Free Software Foundation, either version 3 of the License, or       #
+#  (at your option) any later version.                                     #
+#                                                                          #
+#  This program is distributed in the hope that it will be useful,         #
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of          #
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
+#  GNU General Public License for more details.                            #
+#                                                                          #
+#  You should have received a copy of the GNU General Public License       #
+#  along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#                                                                          #
+#  Author's email: [email protected]                                     #
+#  Github repository: https://github.com/ccie18643/PyTCP                   #
+#                                                                          #
+############################################################################
+
+
+"""
+Module contains methods supporting errors.
+
+pytcp/lib/errors.py
+
+ver 2.7
+"""
+
+
+from __future__ import annotations
+
+
+class PyTcpError(Exception):
+    """
+    Base class for all PyTCP exceptions.
+    """
+
+    ...
+
+
+class UnsupportedCaseError(PyTcpError):
+    """
+    Exception raised when the not supposed to be reached
+    'match' case is being reached for whatever reason.
+    """
+
+    ...
+
+
+class PacketValidationError(PyTcpError):
+    """
+    Exception raised when packet validation fails.
+    """
+
+    ...
+
+
+class PacketIntegrityError(PacketValidationError):
+    """
+    Exception raised when integrity check fails.
+    """
+
+    def __init__(self, message: str):
+        super().__init__("[INTEGRITY]" + message)
+
+
+class PacketSanityError(PacketValidationError):
+    """
+    Exception raised when sanity check fails.
+    """
+
+    def __init__(self, message: str):
+        super().__init__("[SANITY]" + message)

pytcp/lib/protocol_enum.py

@@ -0,0 +1,59 @@
+#!/usr/bin/env python3
+
+############################################################################
+#                                                                          #
+#  PyTCP - Python TCP/IP stack                                             #
+#  Copyright (C) 2020-present Sebastian Majewski                           #
+#                                                                          #
+#  This program is free software: you can redistribute it and/or modify    #
+#  it under the terms of the GNU General Public License as published by    #
+#  the Free Software Foundation, either version 3 of the License, or       #
+#  (at your option) any later version.                                     #
+#                                                                          #
+#  This program is distributed in the hope that it will be useful,         #
+#  but WITHOUT ANY WARRANTY; without even the implied warranty of          #
+#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the           #
+#  GNU General Public License for more details.                            #
+#                                                                          #
+#  You should have received a copy of the GNU General Public License       #
+#  along with this program.  If not, see <https://www.gnu.org/licenses/>.  #
+#                                                                          #
+#  Author's email: [email protected]                                     #
+#  Github repository: https://github.com/ccie18643/PyTCP                   #
+#                                                                          #
+############################################################################
+
+
+"""
+Module contains the ProtocolEnum class.
+
+pytcp/lib/protocol_enum.py
+
+ver 2.7
+"""
+
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import Self
+
+
+class ProtocolEnum(Enum):
+    def __int__(self) -> int:
+        return int(self.value)
+
+    def __str__(self) -> str:
+        return str(self.value)
+
+    @staticmethod
+    def _extract(frame: bytes) -> int:
+        raise NotImplementedError
+
+    @classmethod
+    def from_frame(cls, /, frame: bytes) -> Self:
+        return cls(cls._extract(frame))
+
+    @classmethod
+    def sanity_check(cls, /, frame: bytes) -> bool:
+        return cls._extract(frame) in cls

pytcp/protocols/arp/fpa.py

@@ -41,87 +41,77 @@
 from pytcp.lib.ip4_address import Ip4Address
 from pytcp.lib.mac_address import MacAddress
 from pytcp.lib.tracker import Tracker
-from pytcp.protocols.arp.ps import ARP_HEADER_LEN, ARP_OP_REPLY, ARP_OP_REQUEST
-from pytcp.protocols.ether.ps import ETHER_TYPE_ARP
-
-
-class ArpAssembler:
+from pytcp.protocols.arp.ps import (
+    ARP_HEADER_LEN,
+    Arp,
+    ArpHardwareLength,
+    ArpHardwareType,
+    ArpOperation,
+    ArpProtocolLength,
+    ArpProtocolType,
+)
+
+
+class ArpAssembler(Arp):
     """
     ARP packet assembler support class.
     """
 
-    ether_type = ETHER_TYPE_ARP
-
     def __init__(
         self,
         *,
         sha: MacAddress = MacAddress(0),
         spa: Ip4Address = Ip4Address(0),
         tha: MacAddress = MacAddress(0),
         tpa: Ip4Address = Ip4Address(0),
-        oper: int = ARP_OP_REQUEST,
+        oper: ArpOperation = ArpOperation.REQUEST,
         echo_tracker: Tracker | None = None,
     ) -> None:
         """
         Class constructor.
         """
 
-        assert oper in (ARP_OP_REQUEST, ARP_OP_REPLY), f"{oper=}"
-
         self._tracker = Tracker(prefix="TX", echo_tracker=echo_tracker)
 
-        self._hrtype: int = 1
-        self._prtype: int = 0x0800
-        self._hrlen: int = 6
-        self._prlen: int = 4
-        self._oper: int = oper
-        self._sha: MacAddress = sha
-        self._spa: Ip4Address = spa
-        self._tha: MacAddress = tha
-        self._tpa: Ip4Address = tpa
+        self._hrtype = ArpHardwareType.ETHERNET
+        self._prtype = ArpProtocolType.IP4
+        self._hrlen = ArpHardwareLength.ETHERNET
+        self._prlen = ArpProtocolLength.IP4
+        self._oper = oper
+        self._sha = sha
+        self._spa = spa
+        self._tha = tha
+        self._tpa = tpa
 
     def __len__(self) -> int:
         """
         Length of the packet.
         """
-        return ARP_HEADER_LEN
 
-    def __str__(self) -> str:
-        """
-        Packet log string.
-        """
-        if self._oper == ARP_OP_REQUEST:
-            return (
-                f"ARP request {self._spa} / {self._sha}"
-                f" > {self._tpa} / {self._tha}"
-            )
-        if self._oper == ARP_OP_REPLY:
-            return (
-                f"ARP reply {self._spa} / {self._sha}"
-                f" > {self._tpa} / {self._tha}"
-            )
-        return f"ARP request unknown operation {self._oper}"
+        return ARP_HEADER_LEN
 
     @property
     def tracker(self) -> Tracker:
         """
         Getter for the '_tracker' property.
         """
+
         return self._tracker
 
-    def assemble(self, frame: memoryview) -> None:
+    def assemble(self, /, frame: memoryview) -> None:
         """
         Assemble packet into the raw form.
         """
+
         struct.pack_into(
             "!HH BBH 6s 4s 6s 4s",
             frame,
             0,
-            self._hrtype,
-            self._prtype,
-            self._hrlen,
-            self._prlen,
-            self._oper,
+            int(self._hrtype),
+            int(self._prtype),
+            int(self._hrlen),
+            int(self._prlen),
+            int(self._oper),
             bytes(self._sha),
             bytes(self._spa),
             bytes(self._tha),