JarryShaw · Nov 2, 2026 · Nov 1, 2026
diff --git a/docs/source/contributing/pep.rst b/docs/source/contributing/pep.rst
@@ -42,7 +42,7 @@ the ones outstanding are,
 
 * Link Layer: DSL, EAPOL, FDDI, ISDN, NDP, PPP
 * Internet Layer: ECN, Shim6
-* Transport Layer: DCCP, RSVP
+* Transport Layer: RSVP
 * Application Layer: BGP, DHCP, DHCPv6, DNS, IMAP, LDAP, MQTT, NNTP,
   NTP, ONC/RPC, POP, QUIC, RIP, RTP, SIP, SMTP, SNMP, SSH, Telnet,
   XMPP
@@ -818,12 +818,13 @@ These protocols parse a checksum or CRC field —
 :class:`~pcapkit.protocols.internet.ipx.IPX`,
 :class:`~pcapkit.protocols.internet.mh.MH`,
 :class:`~pcapkit.protocols.application.ospf.OSPF`,
+:class:`~pcapkit.protocols.transport.dccp.DCCP`,
 :class:`~pcapkit.protocols.transport.sctp.SCTP`,
 :class:`~pcapkit.protocols.transport.tcp.TCP` and
 :class:`~pcapkit.protocols.transport.udp.UDP` — and SCTP was the first to
 check whether the value is *right*, through
 :attr:`SCTP.checksum_valid <pcapkit.protocols.transport.sctp.SCTP.checksum_valid>`.
-IPv4, OSPF, TCP and UDP check it too, as do ICMP and ICMPv6, as the
+IPv4, OSPF, TCP, UDP and DCCP check it too, as do ICMP and ICMPv6, as the
 one's-complement half below describes. For HIP, HOPOPT, IPv6-Opts, IPX and MH the
 field is recorded and never questioned, so a corrupted capture parses as cleanly
 as an intact one.
@@ -832,9 +833,9 @@ as an intact one.
 of them is cryptographic and the distinction decides what is actually hard.
 
 **The one's-complement Internet checksum**, which covers IPv4's header, TCP, UDP,
-ICMP/ICMPv6 and OSPF, needs no cryptography at all — it is sixteen-bit addition
+DCCP, ICMP/ICMPv6 and OSPF, needs no cryptography at all — it is sixteen-bit addition
 with end-around carry, and implementing it is an afternoon. What blocks it is the
-**IP pseudo-header**: the TCP, UDP and ICMPv6 checksums are computed over source
+**IP pseudo-header**: the TCP, UDP, DCCP and ICMPv6 checksums are computed over source
 and destination addresses, the protocol number and the payload length, all of
 which live in the *enclosing* layer. So verification needs a parsed protocol to
 reach back to its parent, which is a structural question about
@@ -924,6 +925,20 @@ offload heuristic on :issue:`2470`.
   checksum covers, so it is verified when the fragment holds that much, and
   :attr:`~pcapkit.corekit.checksum.internet.ChecksumStatus.TRUNCATED`
   otherwise.
+* **DCCP covers what its Checksum Coverage gives** (:rfc:`4340#section-9.2`), over
+  a pseudo-header that carries the whole packet's length, as TCP's does, so a
+  fragment is
+  :attr:`~pcapkit.corekit.checksum.internet.ChecksumStatus.NO_PSEUDO_HEADER`
+  too. A coverage running past the packet, which the RFC forbids and has the
+  receiver ignore, is
+  :attr:`~pcapkit.corekit.checksum.internet.ChecksumStatus.INVALID` and
+  warns. Linux, until it dropped DCCP in 6.16, never sent one: its
+  ``dccp_csum_outgoing`` wrote a CsCov of 0 wherever the coverage reached the
+  end of the packet, and ``make()`` does the same when it computes the
+  checksum. No value is
+  :attr:`~pcapkit.corekit.checksum.internet.ChecksumStatus.NOT_COMPUTED`:
+  DCCP has no checksum to leave out, and Linux computed it in software rather
+  than offloading it. Settled at implementation (:issue:`2489`).
 
 The cryptographic half is sequenced for **wave 2 or 3**, and could be done sooner
 since ESP has already laid the groundwork.
@@ -1123,9 +1138,15 @@ Steps`_ above.
 **Wave 2 — the protocol pairs that want a shared abstract base**, per `More
 Protocols, More!!!`_ above: **TLS/SSL with DTLS** and **IGMP** and **DCCP** on
 their own. These are grouped because the shared-base question is the design work
-and doing either half of a pair alone would answer it twice. **DCCP** is the
-transport-layer implementation, tracked by :issue:`2489`, and blocked on
-:issue:`2479` for its pseudo-header checksum.
+and doing either half of a pair alone would answer it twice.
+
+**DCCP — done within wave 2** (:issue:`2489`).
+:class:`~pcapkit.protocols.transport.dccp.DCCP` dissects every :rfc:`4340` packet
+type and DCCP-Listen (:rfc:`5596`), with short and long sequence numbers, and the
+options :rfc:`4340` defines; its checksum is verified and computed over
+:class:`~pcapkit.protocols.misc.checksum.ip_pseudo.IP_Pseudo`, as `Checksum and
+Integrity Verification`_ above describes. The Data Checksum option's CRC-32c is
+recorded and not checked.
 
 **Done within wave 2 — ICMP/ICMPv6 shared base.** :class:`~pcapkit.protocols.internet.icmp.ICMP`
 is the abstract base :class:`~pcapkit.protocols.internet.icmpv4.ICMPv4` and
@@ -1311,7 +1332,7 @@ and its signature parameters could start whenever, since
 :class:`~pcapkit.protocols.internet.esp.ESP` has already established both the
 keying-context channel and the report-rather-than-raise policy. The
 one's-complement half (IPv4, TCP, UDP, ICMP/ICMPv6, OSPF) is **done**
-(:issue:`2470`, :issue:`2472` to :issue:`2475`).
+(:issue:`2470`, :issue:`2472` to :issue:`2475`), and DCCP's with it (:issue:`2489`).
 
 **IP pseudo-header — done** (:issue:`2471`).
 :class:`~pcapkit.protocols.misc.checksum.ip_pseudo.IP_Pseudo` is the

diff --git a/docs/source/ext.rst b/docs/source/ext.rst
@@ -91,6 +91,8 @@ The protocol classes :mod:`pcapkit` ships:
 | subclasses)                                                      | :class:`pcapkit.protocols.transport.udp.UDP`                                                         |
 +                                                                  +----------------+-----------------------+-------------------------------------------------------------+
 |                                                                  | :class:`pcapkit.protocols.transport.sctp.SCTP`                                                       |
++                                                                  +----------------+-----------------------+-------------------------------------------------------------+
+|                                                                  | :class:`pcapkit.protocols.transport.dccp.DCCP`                                                       |
 +------------------------------------------------------------------+----------------+-----------------------+-------------------------------------------------------------+
 |                                                                  |                | :class:`pcapkit.protocols.application.ftp.FTP`                                      |
 +                                                                  + FTP Family     +-----------------------+-------------------------------------------------------------+
@@ -194,6 +196,8 @@ The registry function per protocol type:
 |                   |                                                                   | :func:`~pcapkit.foundation.registry.protocols.register_udp`    | new protocols.     |
 +                   +-------------------------------------------------------------------+----------------------------------------------------------------+                    +
 |                   |                                                                   | :func:`~pcapkit.foundation.registry.protocols.register_sctp`   |                    |
++                   +-------------------------------------------------------------------+----------------------------------------------------------------+                    +
+|                   |                                                                   | :func:`~pcapkit.foundation.registry.protocols.register_dccp`   |                    |
 +-------------------+-------------------------------------------------------------------+----------------------------------------------------------------+--------------------+
 
 A protocol carried over IPX is keyed by IPX Packet Type rather than by IP protocol
@@ -405,6 +409,8 @@ writes them:
 |                   | :class:`~pcapkit.protocols.transport.sctp.SCTP`            | :attr:`SCTP.__parameter__ <pcapkit.protocols.transport.sctp.SCTP.__parameter__>`              | :func:`~pcapkit.foundation.registry.protocols.register_sctp_parameter`     |
 +                   +                                                            +-----------------------------------------------------------------------------------------------+----------------------------------------------------------------------------+
 |                   |                                                            | :attr:`SCTP.__cause__ <pcapkit.protocols.transport.sctp.SCTP.__cause__>`                      | :func:`~pcapkit.foundation.registry.protocols.register_sctp_cause`         |
++                   +------------------------------------------------------------+-----------------------------------------------------------------------------------------------+----------------------------------------------------------------------------+
+|                   | :class:`~pcapkit.protocols.transport.dccp.DCCP`            | :attr:`DCCP.__option__ <pcapkit.protocols.transport.dccp.DCCP.__option__>`                    | :func:`~pcapkit.foundation.registry.protocols.register_dccp_option`        |
 +-------------------+------------------------------------------------------------+-----------------------------------------------------------------------------------------------+----------------------------------------------------------------------------+
 | Application Layer | :class:`~pcapkit.protocols.application.httpv2.HTTPv2`      | :attr:`HTTPv2.__frame__ <pcapkit.protocols.application.httpv2.HTTPv2.__frame__>`              | :func:`~pcapkit.foundation.registry.protocols.register_http_frame`         |
 +-------------------+------------------------------------------------------------+-----------------------------------------------------------------------------------------------+----------------------------------------------------------------------------+

diff --git a/docs/source/pcapkit/const/dccp.rst b/docs/source/pcapkit/const/dccp.rst
@@ -0,0 +1,111 @@
+=====================================================================
+:class:`~pcapkit.protocols.transport.dccp.DCCP` Constant Enumerations
+=====================================================================
+
+.. module:: pcapkit.const.dccp
+
+This module contains all constant enumerations of
+:class:`~pcapkit.protocols.transport.dccp.DCCP` implementations. Available
+enumerations include:
+
+.. list-table::
+
+   * - :class:`DCCP_PacketType <pcapkit.const.dccp.packet_type.PacketType>`
+     - DCCP Packet Types [*]_
+   * - :class:`DCCP_ResetCode <pcapkit.const.dccp.reset_code.ResetCode>`
+     - DCCP Reset Codes [*]_
+   * - :class:`DCCP_Option <pcapkit.const.dccp.option.Option>`
+     - DCCP Option Types [*]_
+   * - :class:`DCCP_Feature <pcapkit.const.dccp.feature.Feature>`
+     - DCCP Feature Numbers [*]_
+   * - :class:`DCCP_AckVectorState <pcapkit.const.dccp.ack_vector_state.AckVectorState>`
+     - DCCP Ack Vector States [*]_
+   * - :class:`DCCP_DropCode <pcapkit.const.dccp.drop_code.DropCode>`
+     - DCCP Drop Codes [*]_
+
+DCCP Packet Types
+=================
+
+.. module:: pcapkit.const.dccp.packet_type
+
+This module contains the constant enumeration for **DCCP Packet Types**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.packet_type.PacketType`.
+
+.. autoclass:: pcapkit.const.dccp.packet_type.PacketType
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+DCCP Reset Codes
+================
+
+.. module:: pcapkit.const.dccp.reset_code
+
+This module contains the constant enumeration for **DCCP Reset Codes**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.reset_code.ResetCode`.
+
+.. autoclass:: pcapkit.const.dccp.reset_code.ResetCode
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+DCCP Option Types
+=================
+
+.. module:: pcapkit.const.dccp.option
+
+This module contains the constant enumeration for **DCCP Option Types**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.option.Option`.
+
+.. autoclass:: pcapkit.const.dccp.option.Option
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+DCCP Feature Numbers
+====================
+
+.. module:: pcapkit.const.dccp.feature
+
+This module contains the constant enumeration for **DCCP Feature Numbers**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.feature.Feature`.
+
+.. autoclass:: pcapkit.const.dccp.feature.Feature
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+DCCP Ack Vector States
+======================
+
+.. module:: pcapkit.const.dccp.ack_vector_state
+
+This module contains the constant enumeration for **DCCP Ack Vector States**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.ack_vector_state.AckVectorState`.
+
+.. autoclass:: pcapkit.const.dccp.ack_vector_state.AckVectorState
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+DCCP Drop Codes
+===============
+
+.. module:: pcapkit.const.dccp.drop_code
+
+This module contains the constant enumeration for **DCCP Drop Codes**,
+which is automatically generated from :class:`pcapkit.vendor.dccp.drop_code.DropCode`.
+
+.. autoclass:: pcapkit.const.dccp.drop_code.DropCode
+   :members:
+   :undoc-members:
+   :show-inheritance:
+
+.. rubric:: Footnotes
+
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-1
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-3
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-5
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-7
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-10
+.. [*] https://www.iana.org/assignments/dccp-parameters/dccp-parameters.xhtml#dccp-parameters-11
diff --git a/docs/source/pcapkit/const/index.rst b/docs/source/pcapkit/const/index.rst
@@ -95,6 +95,7 @@ Transport Layer
 .. toctree::
    :maxdepth: 2
 
+   dccp
    sctp
    tcp
 

diff --git a/docs/source/pcapkit/foundation/registry.rst b/docs/source/pcapkit/foundation/registry.rst
@@ -137,6 +137,10 @@ Transport Layer Registries
 
 .. autofunction:: pcapkit.foundation.registry.protocols.register_sctp_cause
 
+.. autofunction:: pcapkit.foundation.registry.protocols.register_dccp
+
+.. autofunction:: pcapkit.foundation.registry.protocols.register_dccp_option
+
 Application Layer Registries
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

diff --git a/docs/source/pcapkit/protocols/index.rst b/docs/source/pcapkit/protocols/index.rst
@@ -111,7 +111,7 @@ from given information. The class hierarchy of :mod:`pcapkit.protocols`:
        end
 
        subgraph transport [Transport Layer]
-           Transport --> TCP & UDP & SCTP
+           Transport --> TCP & UDP & SCTP & DCCP
        end
 
        B --> Link & Internet & Transport & Application
@@ -171,6 +171,7 @@ from given information. The class hierarchy of :mod:`pcapkit.protocols`:
        click TCP "transport/tcp.html#pcapkit.protocols.transport.tcp.TCP"
        click UDP "transport/udp.html#pcapkit.protocols.transport.udp.UDP"
        click SCTP "transport/sctp.html#pcapkit.protocols.transport.sctp.SCTP"
+       click DCCP "transport/dccp.html#pcapkit.protocols.transport.dccp.DCCP"
 
        click Application "application/application.html#pcapkit.protocols.application.application.Application"
        click HTTP "application/http.html#pcapkit.protocols.application.http.HTTP"
-Original file line number
+Diff line change
@@ Expand Up / @@ -95,6 +95,7 @@ Transport Layer @@
     .. toctree::
        :maxdepth: 2
+       dccp
        sctp
        tcp
@@ Expand Down @@