An overview of the Python SCTP module ===================================== Description ----------- This module is a wrapper for libraries implementing the SCTP protocol and available on *Linux* and *FreeBSD*. This module strictly implements the API described in `RFC 6458 `__. It consists of a pure Python module :py:mod:`sctp` and three C-modules :py:mod:`_sctp.sctp`, :py:mod:`_sctp.sctp_info` and :py:mod:`_sctp.sctp_event`. .. note:: The SCTP module does not implement everything marked as **deprecated** in `RFC 6458 `__ (e.g., :Py:`SCTP_USE_EXT_RCVINFO` socket option, :Py:`sctp_sendmsg()` function,...). The core class is the :py:class:`~sctp.sctp_socket` class. It inherits all attributes and methods from the :py:class:`socket.socket` class in the Python :py:mod:`socket` module (except for the method :py:meth:`~socket.socket.accept` - see note below). To create such a class: .. code-block:: Python >>> from socket import * >>> from sctp import * >>> sock = sctp_socket(AF_INET, SOCK_STREAM) >>> sock.connect(('localhost', 20000)) # method inherited >>> data, addr, info, infotype, flags = sock.sctp_recvv(1024) # new method ... >>> sock.close() # method inherited .. note:: Method :Py:`accept()` of class :py:class:`~sctp.sctp_socket` behaves in the same way as the standard method :py:meth:`~socket.socket.accept`, i.e., it takes no arguments and returns a pair :Py:`(conn, address)`. The only difference is that :Py:`conn` is a :py:class:`~sctp.sctp_socket` object and not a :py:class:`socket.socket` object. `RFC 6458 `__ defines a number of socket options and, where applicable, the corresponding C structures, the latter being available as classes, with the same name, inheriting from :py:class:`dict`. The same applies to SCTP events and notifications, which are also implemented as classes inheriting from :py:class:`dict`. .. warning:: Unlike the standard Python module :py:mod:`socket` module, IPv6 addresses are **necessarily** 4-tuples of the form :Py:`(host, port, flowinfo, scope_id)`, see :ref:`ip-addresses` for details. Class diagrams -------------- Module :py:mod:`sctp` ^^^^^^^^^^^^^^^^^^^^^ .. graphviz:: digraph { rankdir=LR edge [arrowhead="vee", color="#5a6062"] node [shape="box", style=filled, fillcolor="#ffe7d4", color="#5a6062"] a [label="sctp.sctp_socket"] b [ style=none shape = none label = <

Methods

getsockopt()

setsockopt()

sctp_opt_info()

> ] a -> b:m0 c [label="_sctp.sctp.sctp_socket"] d [ style=none shape = none label = <

Properties

sctp_type

sock

Methods

sctp_bindx()

sctp_connectx()

sctp_getladdrs()

sctp_getpaddrs()

sctp_recvv()

sctp_sendv()

sctp_peeloff()

> ] c -> d:m0 o [label="object"] { edge [constraint=false] a -> c -> o } } .. graphviz:: digraph { rankdir=LR edge [arrowhead="vee", arrowtail="vee", color="#5a6062"] node [shape="box", style=filled, fillcolor="#ffe7d4", color="#5a6062"] g [label="sctp.sctp_*"] h [ style=none shape = none label = <

sctp_initmsg

sctp_paddrparams

sctp_paddrinfo

sctp_rtoinfo

sctp_assocparams

sctp_setprim

sctp_setadaptation

sctp_assoc_value

sctp_authkeyid

sctp_sack_info

sctp_default_sndinfo

sctp_default_prinfo

sctp_status

sctp_setpeerprim

sctp_authchunk

sctp_authkey

sctp_event

> ] g -> h [dir=both] a [label="sctp.sctp_generic"] b [ style=none shape = none label = <

Properties

fmt

size

to_bytes

Methods

set_value()

> ] a -> b:m0 { edge [constraint=false] c [label="dict"] g -> a -> c } } Module :py:mod:`~_sctp.sctp_info` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. graphviz:: digraph { rankdir=LR edge [arrowhead="vee", arrowtail="vee", color="#5a6062"] node [shape="box", style=filled, fillcolor="#ffe7d4", color="#5a6062"] g [label="_sctp.sctp_info.sctp_*"] h [ style=none shape = none label = <

sctp_sndinfo

sctp_prinfo

sctp_authinfo

sctp_sendv_spa

sctp_rcvinfo

sctp_nxtinfo

sctp_recvv_rn

> ] g -> h [dir=both] { edge [constraint=false] a [label="dict"] g -> a } } Module :py:mod:`~_sctp.sctp_event` ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. graphviz:: digraph { rankdir=LR edge [arrowhead="vee", color="#5a6062"] node [shape="box", style=filled, fillcolor="#ffe7d4", color="#5a6062"] a [label="_sctp.sctp_event"] b [ style=none shape = none label = <

Methods

parse_notification()

> ] a -> b:m0 } .. _examples: Some examples ------------- A simple *echo* client/server ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ This is the *echo* client/server revisited. Here, both the client and the server use different streams for sending and receiving data. .. literalinclude:: code/echo_client.py :language: Python :caption: echo_client.py The client sends data on stream :Py:`Streams.OUT` (:Py:`1`) and receives it on stream :Py:`Streams.IN` (:Py:`0`). .. literalinclude:: code/echo_server.py :language: Python :caption: echo_server.py The server sends data on stream :Py:`Streams.OUT` (:Py:`0`) and receives it on stream :Py:`Streams.IN` (:Py:`1`). The Python version of the example shown in `Appendix A `__ of RFC 6458 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. literalinclude:: code/one-to-one.py :language: Python :caption: one-to-one.py To test this script with *discard* server on *Linux*, you must first start this server. This requires two steps (as root): #. Edit file :Bash:`/etc/xinetd.d/discard` and set :Bash:`disable=no` for TCP protocol. #. Start *discard* server with command :Bash:`withsctp`: .. code-block:: console # withsctp xinetd And finally, run the script as a non-privileged user: .. code-block:: console $ python3 one_to_one.py The Python version of the example shown in `Appendix B `__ of RFC 6458 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ .. literalinclude:: code/one-to-many.py :language: Python :caption: one-to-many.py To test this script, first run it as root (port=9 is a priviliged one): .. code-block:: console :caption: root window # python3 one-to-many.py In another window, run :Bash:`one_to_one.py` as a non-privileged user: .. code-block:: console :caption: user window $ python3 one_to_one.py In root window, you will see something like that: .. code-block:: console :caption: root window # python3 one-to-many.py Communication up (streams (in/out)=(2048/10)). ^^^ Adaptation indication 01020304 received. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=0 , unordered, tsn=3093043390, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=1 , unordered, tsn=3093043391, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=2 , unordered, tsn=3093043392, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=3 , unordered, tsn=3093043393, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=4 , unordered, tsn=3093043394, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=5 , unordered, tsn=3093043395, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=6 , unordered, tsn=3093043396, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=7 , unordered, tsn=3093043397, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=8 , unordered, tsn=3093043398, ppid=1234. Message received from ::ffff:127.0.0.1:52378: len=1000, sid=9 , unordered, tsn=3093043399, ppid=1234. ^^^ Shutdown received. Communication completed. .. _rfc6458: https://datatracker.ietf.org/doc/html/rfc6458 .. _rfc6458appA: https://datatracker.ietf.org/doc/html/rfc6458#appendix-A .. _rfc6458appB: https://datatracker.ietf.org/doc/html/rfc6458#appendix-B