IPv4 Datagram Reassembly
========================

.. module:: pcapkit.foundation.reassembly.ipv4

:mod:`pcapkit.foundation.reassembly.ipv4` contains
:class:`~pcapkit.foundation.reassembly.ipv4.IPv4_Reassembly`
only, which reconstructs fragmented IPv4 packets back to
origin. Please refer to :doc:`ip` for more information.

.. autoclass:: pcapkit.foundation.reassembly.ipv4.IPv4_Reassembly
   :no-members:
   :show-inheritance:

   :param \*args: Arbitrary positional arguments.
   :param \*\*kwargs: Arbitrary keyword arguments.

   .. autoproperty:: name
   .. autoproperty:: protocol

Terminology
-----------

.. glossary::

   ipv4.packet
       Data structure for **IPv4 datagram reassembly**
       (:meth:`IPv4_Reassembly.reassembly <pcapkit.foundation.reassembly.reassembly.Reassembly.reassembly>`)
       is as following:

       .. code-block:: python

          packet_dict = dict(
            bufid = tuple(
                ipv4.src,                   # source IP address
                ipv4.dst,                   # destination IP address
                ipv4.id,                    # identification
                ipv4.proto,                 # payload protocol type
            ),
            num = frame.number,             # original packet range number
            fo = ipv4.frag_offset,          # fragment offset
            ihl = ipv4.hdr_len,             # internet header length
            mf = ipv4.flags.mf,             # more fragment flag
            tl = ipv4.len,                  # total length, header includes
            header = ipv4.header,           # raw bytes type header
            payload = ipv4.payload,         # raw bytearray type payload
          )

   ipv4.datagram
       Data structure for **reassembled IPv4 datagram** (element from
       :attr:`IPv4_Reassembly.datagram <pcapkit.foundation.reassembly.reassembly.Reassembly.datagram>`
       *tuple*) is as following:

       .. code-block:: text

          (tuple) datagram
           |--> (Info) data
           |     |--> 'completed' : (bool) True --> implemented
           |     |--> 'id' : (Info) original packet identifier
           |     |            |--> 'src' --> (IPv4Address) ipv4.src
           |     |            |--> 'dst' --> (IPv4Address) ipv4.dst
           |     |            |--> 'id' --> (int) ipv4.id
           |     |            |--> 'proto' --> (EtherType) ipv4.proto
           |     |--> 'index' : (tuple) packet numbers
           |     |               |--> (int) original packet range number
           |     |--> 'header' : (bytes) IPv4 header
           |     |--> 'payload' : (bytes) reassembled IPv4 payload
           |     |--> 'packet' : (Protocol) parsed reassembled payload
           |--> (Info) data
           |     |--> 'completed' : (bool) False --> not implemented
           |     |--> 'id' : (Info) original packet identifier
           |     |            |--> 'src' --> (IPv4Address) ipv4.src
           |     |            |--> 'dst' --> (IPv4Address) ipv4.dst
           |     |            |--> 'id' --> (int) ipv4.id
           |     |            |--> 'proto' --> (EtherType) ipv4.proto
           |     |--> 'index' : (tuple) packet numbers
           |     |               |--> (int) original packet range number
           |     |--> 'header' : (bytes) IPv4 header
           |     |--> 'payload' : (tuple) partially reassembled IPv4 payload
           |     |                 |--> (bytes) IPv4 payload fragment
           |     |                 |--> ...
           |     |--> 'packet' : (None)
           |--> (Info) data ...

   ipv4.buffer
       Data structure for internal buffering when performing reassembly algorithms
       (:attr:`IPv4_Reassembly._buffer <pcapkit.foundation.reassembly.reassembly.Reassembly._buffer>`)
       is as following:

       .. code-block:: text

          (dict) buffer --> memory buffer for reassembly
           |--> (tuple) BUFID : (dict)
           |     |--> ipv4.src       |
           |     |--> ipv4.dst       |
           |     |--> ipv4.id        |
           |     |--> ipv4.proto     |
           |                         |--> 'TDL' : (int) total data length
           |                         |--> 'RCVBT' : (bytearray) fragment received bit table
           |                         |               |--> (bytes) b'\\x00' -> not received
           |                         |               |--> (bytes) b'\\x01' -> received
           |                         |               |--> (bytes) ...
           |                         |--> 'index' : (list) list of reassembled packets
           |                         |               |--> (int) packet range number
           |                         |--> 'header' : (bytes) header buffer
           |                         |--> 'datagram' : (bytearray) data buffer, holes set to b'\\x00'
           |--> (tuple) BUFID ...