Skip to content

protocols: bind FTP-DATA, HTTP-alt, OSPF, L2TP and the 802.1ad S-Tag, and fix four dispatch defects #436

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
JarryShaw merged 7 commits into from
Sep 17, 2026
Merged

protocols: bind FTP-DATA, HTTP-alt, OSPF, L2TP and the 802.1ad S-Tag, and fix four dispatch defects #436

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
7 commits
Select commit Hold shift + click to select a range
c1f8440
protocols: bind the S-Tag, FTP-DATA, HTTP-alt, OSPF and L2TP to the t…
JarryShaw Sep 17, 2026
70c6ebb
Merge remote-tracking branch 'origin/main' into feat/protocol-binding…
JarryShaw Sep 17, 2026
cf7f0f2
docs: name VLAN as the shared-ABC precedent for an identical-layout pair
JarryShaw Sep 17, 2026
9262afb
docs: count the port bindings and the port numbers separately, since …
JarryShaw Sep 17, 2026
55dfd11
Merge branch 'main' into feat/protocol-bindings-and-stag
JarryShaw Sep 17, 2026
15a91cd
protocols: one module per registry index -- split the VLAN tags and t…
JarryShaw Sep 17, 2026
c8b2f68
protocols: centre the new module headings on their rules, align the Q…
JarryShaw Sep 17, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
10 changes: 8 additions & 2 deletions docs/source/ext.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -30,11 +30,17 @@ The following table shows all available protocol classes in :mod:`pcapkit`:
+ Link Layer +----------------+-----------------------+-------------------------------------------------------------+
| (:class:`~pcapkit.protocols.link.link.Link` subclasses) | :class:`pcapkit.protocols.link.ethernet.Ethernet` |
+ +----------------+-----------------------+-------------------------------------------------------------+
| | :class:`pcapkit.protocols.link.l2tp.L2TP` |
| | | :class:`pcapkit.protocols.link.l2tp.L2TP` |
+ + +-----------------------+-------------------------------------------------------------+
| | L2TP Family | :class:`pcapkit.protocols.link.l2tpv2.L2TPv2` |
+ +----------------+-----------------------+-------------------------------------------------------------+
| | :class:`pcapkit.protocols.link.ospf.OSPF` |
+ +----------------+-----------------------+-------------------------------------------------------------+
| | :class:`pcapkit.protocols.link.vlan.VLAN` |
| | | :class:`pcapkit.protocols.link.vlan.VLAN` |
+ + +-----------------------+-------------------------------------------------------------+
| | VLAN Family | :class:`pcapkit.protocols.link.c_tag.C_Tag` |
+ + +-----------------------+-------------------------------------------------------------+
| | | :class:`pcapkit.protocols.link.s_tag.S_Tag` |
+------------------------------------------------------------------+----------------+-----------------------+-------------------------------------------------------------+
| | | :class:`pcapkit.protocols.internet.ip.IP` |
+ + +-----------------------+-------------------------------------------------------------+
Expand Down
11 changes: 11 additions & 0 deletions docs/source/pcapkit/protocols/index.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -38,6 +38,14 @@ diagram of the class hierarchy of :mod:`pcapkit.protocols`:
RARP --> DRARP
end
end

subgraph vlan [VLAN Family]
VLAN --> C_Tag & S_Tag
end

subgraph l2tp [L2TP Family]
L2TP --> L2TPv2
end
end

subgraph internet [Internet Layer]
Expand Down Expand Up @@ -100,8 +108,11 @@ diagram of the class hierarchy of :mod:`pcapkit.protocols`:
click Link "/pcapkit/protocols/link/link.html#pcapkit.protocols.link.Link"
click Ethernet "/pcapkit/protocols/link/ethernet.html#pcapkit.protocols.link.ethernet.Ethernet"
click L2TP "/pcapkit/protocols/link/l2tp.html#pcapkit.protocols.link.l2tp.L2TP"
click L2TPv2 "/pcapkit/protocols/link/l2tpv2.html#pcapkit.protocols.link.l2tpv2.L2TPv2"
click OSPF "/pcapkit/protocols/link/ospf.html#pcapkit.protocols.link.ospf.OSPF"
click VLAN "/pcapkit/protocols/link/vlan.html#pcapkit.protocols.link.vlan.VLAN"
click C_Tag "/pcapkit/protocols/link/c_tag.html#pcapkit.protocols.link.c_tag.C_Tag"
click S_Tag "/pcapkit/protocols/link/s_tag.html#pcapkit.protocols.link.s_tag.S_Tag"
click ARP "/pcapkit/protocols/link/arp.html#pcapkit.protocols.link.arp.ARP"
click InARP "/pcapkit/protocols/link/arp.html#pcapkit.protocols.link.arp.InARP"
click RARP "/pcapkit/protocols/link/rarp.html#pcapkit.protocols.link.rarp.RARP"
Expand Down
39 changes: 39 additions & 0 deletions docs/source/pcapkit/protocols/link/c_tag.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
C_Tag - 802.1Q Customer VLAN Tag Type
=====================================

.. module:: pcapkit.protocols.link.c_tag

:mod:`pcapkit.protocols.link.c_tag` contains
:class:`~pcapkit.protocols.link.c_tag.C_Tag` only, which implements extractor for
the 802.1Q Customer VLAN Tag Type (C-Tag, formerly the Q-Tag) [*]_, EtherType
``0x8100``.

Its structure, and all of its parsing and construction, come from
:class:`~pcapkit.protocols.link.vlan.VLAN`; this class adds only the tag's own
identity -- :attr:`~pcapkit.protocols.link.c_tag.C_Tag.name`,
:attr:`~pcapkit.protocols.link.c_tag.C_Tag.alias`,
:attr:`~pcapkit.protocols.link.c_tag.C_Tag.info_name` -- and its registry index.

It lives in a module of its own rather than beside
:class:`~pcapkit.protocols.link.s_tag.S_Tag` because the two are reached through
*different* registry indices, ``0x8100`` against ``0x88A8``, which is the
project's rule for when protocols share a module. Contrast
:class:`~pcapkit.protocols.link.arp.InARP`, which shares
:mod:`~pcapkit.protocols.link.arp` with :class:`~pcapkit.protocols.link.arp.ARP`
precisely because it inherits its index.

.. autoclass:: pcapkit.protocols.link.c_tag.C_Tag
:no-members:
:show-inheritance:

.. autoproperty:: name
.. autoproperty:: alias
.. autoproperty:: info_name

.. automethod:: id

.. automethod:: __index__

.. rubric:: Footnotes

.. [*] https://en.wikipedia.org/wiki/IEEE_802.1Q
3 changes: 3 additions & 0 deletions docs/source/pcapkit/protocols/link/index.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -16,8 +16,11 @@ link layer, with detailed implementation and methods.
arp
rarp
l2tp
l2tpv2
ospf
vlan
c_tag
s_tag

.. todo::

Expand Down
138 changes: 60 additions & 78 deletions docs/source/pcapkit/protocols/link/l2tp.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -4,93 +4,75 @@ L2TP - Layer Two Tunnelling Protocol
.. module:: pcapkit.protocols.link.l2tp

:mod:`pcapkit.protocols.link.l2tp` contains
:class:`~pcapkit.protocols.link.l2tp.L2TP` only,
which implements extractor for Layer Two Tunnelling
Protocol (L2TP) [*]_, whose structure is described
as below:

.. table::

======= ===== ===================== ==========================================
Octets Bits Name Description
======= ===== ===================== ==========================================
0 0 ``l2tp.flags`` Flags and Version Info
------- ----- --------------------- ------------------------------------------
0 0 ``l2tp.flags.type`` Type (control / data)
------- ----- --------------------- ------------------------------------------
0 1 ``l2tp.flags.len`` Length
------- ----- --------------------- ------------------------------------------
0 2 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
0 4 ``l2tp.flags.seq`` Sequence
------- ----- --------------------- ------------------------------------------
0 5 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
0 6 ``l2tp.flags.offset`` Offset
------- ----- --------------------- ------------------------------------------
0 7 ``l2tp.flags.prio`` Priority
------- ----- --------------------- ------------------------------------------
1 8 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
1 12 ``l2tp.version`` Version (``2``)
------- ----- --------------------- ------------------------------------------
2 16 ``l2tp.length`` Length (optional by ``len``)
------- ----- --------------------- ------------------------------------------
4 32 ``l2tp.tunnelid`` Tunnel ID
------- ----- --------------------- ------------------------------------------
6 48 ``l2tp.sessionid`` Session ID
------- ----- --------------------- ------------------------------------------
8 64 ``l2tp.ns`` Sequence Number (optional by ``seq``)
------- ----- --------------------- ------------------------------------------
10 80 ``l2tp.nr`` Next Sequence Number (optional by ``seq``)
------- ----- --------------------- ------------------------------------------
12 96 ``l2tp.offset`` Offset Size (optional by ``offset``)
======= ===== ===================== ==========================================
:class:`~pcapkit.protocols.link.l2tp.L2TP` only, an abstract base class for the
Layer Two Tunnelling Protocol family [*]_. The concrete versions live in modules
of their own:

.. list-table::
:header-rows: 1

* - Version
- Class
- Specification
* - L2TPv2
- :class:`~pcapkit.protocols.link.l2tpv2.L2TPv2`
- :rfc:`2661`

Only L2TPv2 is implemented.

The base deliberately carries **no header parsing at all**, in the way
:class:`~pcapkit.protocols.internet.ip.IP` carries none for its family. That is
not tidiness: the versions genuinely do not share a header. All that is common
across them is the *first 16-bit word carrying a version nibble at bits 12-15*;
everything after it differs, so a base that parsed further would be assuming one
version's layout for all of them.

What the family still wants
---------------------------

**L2TPv3** [:rfc:`3931`] has a different session header and a different control
message header from v2, and is reachable two ways -- over UDP port 1701 like v2,
and directly over IP as **protocol number 115**. That second route is why
:attr:`Internet.__proto__ <pcapkit.protocols.internet.internet.Internet.__proto__>`
leaves 115 unbound today: the binding waits on an ``L2TPv3`` class, not on a
different framing decision. It also means v3 is the first member of this family
to have a real :meth:`~pcapkit.protocols.protocol.ProtocolBase.__index__`, and so
the first that must have a module of its own under the project's one-module-per-index
rule.

**L2F** [:rfc:`2341`] is reached when the version nibble reads ``1``. It is *not*
an earlier version of L2TP: :rfc:`2661` §3.1 requires ``Ver`` to be 2 and reserves
the value 1 "to permit detection of L2F packets should they arrive intermixed with
L2TP packets". L2F is a separate protocol with its own header. It is therefore to
be implemented as ``L2F``, the canonical name, carrying ``L2TPv1`` only as an
alias in its :meth:`~pcapkit.protocols.protocol.ProtocolBase.id` -- the same
relationship HTTP/3 has to QUIC. c.f.
:meth:`HTTPv1.id <pcapkit.protocols.application.httpv1.HTTP.id>` for how a
version-flavoured alias is spelled: canonical name first, alias second, since
callers take element zero as canonical.

Selecting a version
-------------------

Nothing dispatches on the version nibble yet, because only one version exists.
When a second lands, the mechanism it wants already has a precedent in
:class:`~pcapkit.protocols.application.http.HTTP`, which reads a version and
delegates to a per-version class. L2TP is the easier case:
:meth:`HTTP._guess_version <pcapkit.protocols.application.http.HTTP._guess_version>`
has to *trial-parse* each candidate because the wire format carries no version
field, whereas L2TP states its version explicitly in those four bits. So a
deterministic switch on ``Ver`` is enough, and no new registry is needed.

.. autoclass:: pcapkit.protocols.link.l2tp.L2TP
:no-members:
:show-inheritance:

.. autoproperty:: name
.. autoproperty:: length
.. autoproperty:: type
.. autoproperty:: info_name

.. automethod:: read
.. automethod:: make

.. automethod:: _make_data
.. automethod:: id

.. automethod:: __index__

Header Schemas
--------------

.. module:: pcapkit.protocols.schema.link.l2tp

.. autoclass:: pcapkit.protocols.schema.link.l2tp.L2TP
:members:
:show-inheritance:

Type Stubs
~~~~~~~~~~

.. autoclass:: pcapkit.protocols.schema.link.l2tp.FlagsType
:members:
:show-inheritance:

Data Models
-----------

.. module:: pcapkit.protocols.data.link.l2tp

.. autoclass:: pcapkit.protocols.data.link.l2tp.L2TP
:members:
:show-inheritance:

.. autoclass:: pcapkit.protocols.data.link.l2tp.Flags
:members:
:show-inheritance:

.. rubric:: Footnotes

.. [*] https://en.wikipedia.org/wiki/Layer_2_Tunneling_Protocol
114 changes: 114 additions & 0 deletions docs/source/pcapkit/protocols/link/l2tpv2.rst
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,114 @@
L2TPv2 - Layer Two Tunnelling Protocol version 2
================================================

.. module:: pcapkit.protocols.link.l2tpv2

:mod:`pcapkit.protocols.link.l2tpv2` contains
:class:`~pcapkit.protocols.link.l2tpv2.L2TPv2` only, which implements extractor
for the Layer Two Tunnelling Protocol version 2 (L2TPv2) [*]_ as specified by
:rfc:`2661` -- a 16-bit tunnel ID and a 16-bit session ID, with the version nibble
reading ``2``. It is dispatched from
:attr:`UDP.__proto__ <pcapkit.protocols.transport.udp.UDP.__proto__>` at port
1701. Its structure is described as below:

.. table::

======= ===== ===================== ==========================================
Octets Bits Name Description
======= ===== ===================== ==========================================
0 0 ``l2tp.flags`` Flags and Version Info
------- ----- --------------------- ------------------------------------------
0 0 ``l2tp.flags.type`` Type (control / data)
------- ----- --------------------- ------------------------------------------
0 1 ``l2tp.flags.len`` Length
------- ----- --------------------- ------------------------------------------
0 2 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
0 4 ``l2tp.flags.seq`` Sequence
------- ----- --------------------- ------------------------------------------
0 5 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
0 6 ``l2tp.flags.offset`` Offset
------- ----- --------------------- ------------------------------------------
0 7 ``l2tp.flags.prio`` Priority
------- ----- --------------------- ------------------------------------------
1 8 Reserved (must be zero ``x00``)
------- ----- --------------------- ------------------------------------------
1 12 ``l2tp.version`` Version (``2``)
------- ----- --------------------- ------------------------------------------
2 16 ``l2tp.length`` Length (optional by ``len``)
------- ----- --------------------- ------------------------------------------
4 32 ``l2tp.tunnelid`` Tunnel ID
------- ----- --------------------- ------------------------------------------
6 48 ``l2tp.sessionid`` Session ID
------- ----- --------------------- ------------------------------------------
8 64 ``l2tp.ns`` Sequence Number (optional by ``seq``)
------- ----- --------------------- ------------------------------------------
10 80 ``l2tp.nr`` Next Sequence Number (optional by ``seq``)
------- ----- --------------------- ------------------------------------------
12 96 ``l2tp.offset`` Offset Size (optional by ``offset``)
======= ===== ===================== ==========================================

.. note::

The parsed datagram appears under ``l2tp``, not ``l2tpv2``:
:attr:`~pcapkit.protocols.link.l2tp.L2TP.info_name` is declared on the
version-agnostic base so that a consumer finds the data at the same key
whichever version was on the wire. The version is reported by
:attr:`~pcapkit.protocols.link.l2tpv2.L2TPv2.alias` instead.

IANA protocol number 115 (``L2TP``) is deliberately left unbound. It
references :rfc:`3931`, i.e. **L2TPv3**, whose session and control message
headers are a different shape -- so the binding waits on an ``L2TPv3`` class
rather than on this one. See :mod:`pcapkit.protocols.link.l2tp`.

.. autoclass:: pcapkit.protocols.link.l2tpv2.L2TPv2
:no-members:
:show-inheritance:

.. autoproperty:: name
.. autoproperty:: alias
.. autoproperty:: version
.. autoproperty:: length
.. autoproperty:: type

.. automethod:: id
.. automethod:: read
.. automethod:: make

.. automethod:: _make_data

.. automethod:: __index__

Header Schemas
--------------

.. module:: pcapkit.protocols.schema.link.l2tp

.. autoclass:: pcapkit.protocols.schema.link.l2tp.L2TP
:members:
:show-inheritance:

Type Stubs
~~~~~~~~~~

.. autoclass:: pcapkit.protocols.schema.link.l2tp.FlagsType
:members:
:show-inheritance:

Data Models
-----------

.. module:: pcapkit.protocols.data.link.l2tp

.. autoclass:: pcapkit.protocols.data.link.l2tp.L2TP
:members:
:show-inheritance:

.. autoclass:: pcapkit.protocols.data.link.l2tp.Flags
:members:
:show-inheritance:

.. rubric:: Footnotes

.. [*] https://en.wikipedia.org/wiki/Layer_2_Tunneling_Protocol
Loading