IPv6 Datagram Reassembly¶

pcapkit.foundation.reassembly.ipv6 contains IPv6 only, which reconstructs fragmented IPv6 packets back to origin. Please refer to Base Class for more information.

class pcapkit.foundation.reassembly.ipv6.IPv6(*, strict=True, store=True)[source]¶

Bases: IP

Reassembly for IPv6 payload.

Parameters:

strict (bool) – if return all datagrams (including those not implemented) when submit
store (bool) – if store reassembled datagram in memory, i.e., self._dtgram (if not, datagram will be discarded after callback)

Example

>>> from pcapkit.foundation.reassembly import IPv6
# Initialise instance:
>>> ipv6_reassembly = IPv6()
# Call reassembly:
>>> ipv6_reassembly(packet_dict)
# Fetch result:
>>> result = ipv6_reassembly.datagram

__protocol_name__: str = 'IPv6'¶: Protocol name of current reassembly object.

__protocol_type__(file=None, length=None, **kwargs): Type[Protocol] = <class 'pcapkit.protocols.internet.ipv6.IPv6'>¶: Protocol of current reassembly object.

Terminology¶

reasm.ipv6.packet¶

Data structure for IPv6 datagram reassembly (IPv6.reassembly) is as following:

packet_dict = dict(
  bufid = tuple(
      ipv6.src,                   # source IP address
      ipv6.dst,                   # destination IP address
      ipv6.label,                 # label
      ipv6_frag.next,             # next header field in IPv6 Fragment Header
  ),
  num = frame.number,             # original packet range number
  fo = ipv6_frag.offset,          # fragment offset
  ihl = ipv6.hdr_len,             # header length, only headers before IPv6-Frag
  mf = ipv6_frag.mf,              # more fragment flag
  tl = ipv6.len,                  # total length, header includes
  header = ipv6.header,           # raw bytes type header before IPv6-Frag
  payload = ipv6.payload,         # raw bytearray type payload after IPv6-Frag
)

reasm.ipv6.datagram¶

Data structure for reassembled IPv6 datagram (element from IPv6.datagram tuple) is as following:

(tuple) datagram
 |--> (Info) data
 |     |--> 'completed' : (bool) True --> implemented
 |     |--> 'id' : (Info) original packet identifier
 |     |            |--> 'src' --> (IPv6Address) ipv6.src
 |     |            |--> 'dst' --> (IPv6Address) ipv6.dst
 |     |            |--> 'id' --> (int) ipv6.label
 |     |            |--> 'proto' --> (EtherType) ipv6_frag.next
 |     |--> 'index' : (tuple) packet numbers
 |     |               |--> (int) original packet range number
 |     |--> 'payload' : (bytes) reassembled IPv4 packet
 |     |--> 'packet' : (Protocol) parsed reassembled payload
 |--> (Info) data
 |     |--> 'completed' : (bool) False --> not implemented
 |     |--> 'id' : (Info) original packet identifier
 |     |            |--> 'src' --> (IPv6Address) ipv6.src
 |     |            |--> 'dst' --> (IPv6Address) ipv6.dst
 |     |            |--> 'id' --> (int) ipv6.id
 |     |            |--> 'proto' --> (EtherType) ipv6_frag.next
 |     |--> '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 ...

reasm.ipv6.buffer¶

Data structure for internal buffering when performing reassembly algorithms (IPv6._buffer) is as following:

(dict) buffer --> memory buffer for reassembly
 |--> (tuple) BUFID : (dict)
 |     |--> ipv6.src       |
 |     |--> ipc6.dst       |
 |     |--> ipv6.label     |
 |     |--> ipv6_frag.next |
 |                         |--> '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 ...