Module _sctp.sctp¶

IP addresses¶

The format of IPv4 addresses is identical to that of the standard Python socket module. Thus, such an address is a 2-tuple (host, port).

Unlike the standard Python socket module (where IPv6 addresses can be 2-tuples), IPv6 addresses here are necessarily 4-tuples of the form (host, port, flowinfo, scope_id). For example, the address ('::1', 2000) will be interpreted as an IPv4 address, which will trigger an error.

For instance, we must be able to distinguish between ('localhost', 2000) and ('localhost', 2000, 0, 0), as shown in the following example:

>>> sock = sctp_socket(AF_INET6, SOCK_STREAM)
>>> sock.sctp_bindx((('localhost', 2000), ('localhost', 2000, 0, 0)),\
             SCTP_BINDX_ADD_ADDR)

Functions¶

Creating SCTP sockets¶

class _sctp.sctp.sctp_socket(family, type, proto=IPPROTO_SCTP)¶

Create a new SCTP socket object using the given address family, socket type and protocol number. Address family must be AF_INET or AF_INET6. Socket type must be SOCK_STREAM or SOCK_SEQPACKET and protocol number must be IPPROTO_SCTP.

Raises SCTPError when one of the arguments is invalid.

Note

Newly created SCTP sockets inherit all methods and attributes from sockets in the standard Python socket module.

Other functions¶

Two utility functions (not defined in RFC 6458):

_sctp.sctp.ipaddr_to_sockaddr_storage(ip_addr)¶

Parameters:: ip_addr – an IPv4 address (host, port) or an IPv6 address (host, port, flowinfo, scope_id)
Returns:: a struct sockaddr_storage (See RFC 3493 – section-3.10) as a bytes object
Raise:: TypeError if ip_addr is not a valid IPv4/v6 address.

_sctp.sctp.sockaddr_storage_to_ipaddr(bytes)¶

Parameters:: bytes – a struct sockaddr_storage (see RFC 3493 – section-3.10) as a bytes object
Returns:: an IPv4 address (host, port) or an IPv6 address (host, port, flowinfo, scope_id)

If bytes cannnot be interpreted as struct sockaddr_storage, function sockaddr_storage_to_ipaddr() returns ('???', 0) or ('???', 0, 0, 0) (no exception raised).

SCTP Socket Objects¶

Attributes¶

sctp_socket.sctp_type¶: Is either 'one-to-one' or 'one-to-many' depending on whether the socket type is SOCK_STREAM or SOCK_SEQPACKET.

sctp_socket.sock¶: The underlying socket.socket.

Note

This read-only attribute is for internal use only.

Methods¶

Note

In all methods that take an iterable of IPv4/IPv6 addresses as an argument, the TypeError exception is thrown if the socket is an IPv4 socket and there are one or more IPv6 addresses among the addresses.

sctp_socket.sctp_bindx(addrs, flags)¶

Parameters:

addrs – an iterable of IPv4/IPv6 addresses
flags – must be SCTP_BINDX_ADD_ADDR or SCTP_BINDX_REM_ADDR

Returns:

None

Raise:

TypeError, ValueError or OSError

This method is a wrapper for function sctp_bindx() described in RFC 6458 – section-9.1.

sctp_socket.sctp_connectx(addrs, *, assoc_id=False)¶

Parameters:

addrs – an iterable of IPv4/IPv6 addresses
assoc_id – boolean

Returns:

None if assoc_id is False or “association identifier” otherwise

Raise:

TypeError, ValueError or OSError

This method is a wrapper for function sctp_connectx() described in RFC 6458 – section-9.9.

sctp_socket.sctp_getladdrs([assoc_id])¶

Parameters:: assoc_id – identifier of the association to query (int32_t)
Returns:: a tuple of IPv4/IPv6 addresses or None

This method is a wrapper for function sctp_getladdrs() described in RFC 6458 – section-9.5.

sctp_socket.sctp_getpaddrs([assoc_id])¶

Parameters:: assoc_id – identifier of the association to query (int32_t)
Returns:: a tuple of IPv4/IPv6 addresses or None

This method is a wrapper for function sctp_getpaddrs() described in RFC 6458 – section-9.3.

sctp_socket.sctp_recvv(bufsize)¶

Parameters:

bufsize – size of the bytes object receiving the data

Returns:

a 5-tuple (data, addr, info, infotype, flags) where:

data is a bytes object holding the data received (up to bufsize)
addr: sender address
info is either a sctp_rcvinfo or a sctp_nxtinfo or a sctp_recvv_rn object
infotype is either the constant SCTP_RECVV_NOINFO or SCTP_RECVV_RCVINFO or SCTP_RECVV_NXTINFO or SCTP_RECVV_RN
flags: received message flags (e.g., MSG_NOTIFICATION)

Raise:

TypeError, ValueError or OSError

This method is a wrapper for function sctp_recvv() described in RFC 6458 – section-9.13.

In order to receive attribures sctp_rcvinfo and sctp_nxtinfo, you must first activate socket options SCTP_RECVRCVINFO and SCTP_RECVNXTINFO respectively as shown below:

>>> sock = sctp_socket(AF_INET SOCK_STREAM)
>>> sock.setsockopt(IPPROTO_SCTP, SCTP_RECVRCVINFO, 1)
... # waiting for data
>>> sock.sctp_recvv(1024)
>>> _, _, info, infotype, _ = s.sctp_recvv(1024)
>>> print(infotype == SCTP_RECVV_RCVINFO)
True
>>> print(info)
{'rcv_sid': 0, 'rcv_ssn': 0, 'rcv_flags': 0, 'rcv_ppid': 0, 'rcv_tsn': 188475,
 'rcv_cumtsn': 0, 'rcv_context': 0, 'rcv_assoc_id': 955}

An other example with both options:

>>> sock = sctp_socket(AF_INET SOCK_STREAM)
>>> sock.setsockopt(IPPROTO_SCTP, SCTP_RECVRCVINFO, 1)
>>> sock.setsockopt(IPPROTO_SCTP, SCTP_RECVNXTINFO, 1)
... # waiting for data
>>> sock.sctp_recvv(1024)
>>> _, _, info, infotype, _ = s.sctp_recvv(1024)
>>> print(infotype == SCTP_RECVV_RN)
True
>>> print(info.nxtinfo)
{'nxt_sid': 1, 'nxt_flags': 0, 'nxt_ppid': 0, 'nxt_length': 68,
 'nxt_assoc_id': 23}

Note

An option may have been requested but not received.

sctp_socket.sctp_sendv(data[, addrs[, info[, flags]]])¶

Parameters:

data – data to send: an iterable of bytes object
addrs – destination addresses: an iterable of IPv4/v6 addresses or None
info – attributes that can be used to describe a message to be sent or None. The info parameter can be either a sctp_sndinfo or a sctp_prinfo or a sctp_authinfo or a sctp_sendv_spa object
flags – the same flags as used by the sendmsg() call flags (e.g., MSG_DONTROUTE). Default value is 0

Returns:

number of bytes sent

Raise:

TypeError, ValueError or OSError

This method is a wrapper for function sctp_sendv() described in RFC 6458 – section-9.12.

Two examples showing how to use the info parameter:

sending data on stream number 5,

>>> sock = sctp_socket(AF_INET6 SOCK_STREAM)
...
>>> info = sctp_sndinfo(snd_sid=5)
>>> noc = sock.sctp_sendv((b'some data',), None, info)
>>> print(noc)
9

sending data on stream number 5 and setting lifetime to 1 second,

>>> sock = sctp_socket(AF_INET6 SOCK_STREAM)
...
>>> sndinfo = sctp_sndinfo(snd_sid=5)
>>> prinfo = sctp_prinfo(pr_policy=SCTP_PR_SCTP_TTL, pr_value=1000)
>>> spa = sctp_sendv_spa((sndinfo, prinfo))
>>> noc = sock.sctp_sendv((b'some data',), None, spa)

sctp_socket._getsockopt(level, optname, optval)¶

Parameters:

level (int) – option level
optname (int) – option name
optval (bytes) – option value

For example, when the level is IPPROTO_SCTP and the option is SCTP_PEER_ADDR_PARAMS, you need to pass a partially pre-filled bytes object as the option value. However, the method getsockopt() provided by the standard Python socket module takes an integer (optional) as its last argument. Hence the need to introduce this auxiliary method.

Note

This method is intended for internal use only.

Constants¶

This module export the following constants:

_sctp.sctp.IPPROTO_SCTP¶

sctp_sendv() – sctp_recvv() attributes:

_sctp.sctp.SCTP_RECVRCVINFO¶
_sctp.sctp.SCTP_RECVNXTINFO¶
_sctp.sctp.SCTP_SENDV_NOINFO¶
_sctp.sctp.SCTP_SENDV_SNDINFO¶
_sctp.sctp.SCTP_SENDV_PRINFO¶
_sctp.sctp.SCTP_SENDV_AUTHINFO¶
_sctp.sctp.SCTP_SENDV_SPA¶
_sctp.sctp.SCTP_SEND_SNDINFO_VALID¶
_sctp.sctp.SCTP_SEND_PRINFO_VALID¶
_sctp.sctp.SCTP_SEND_AUTHINFO_VALID¶
_sctp.sctp.SCTP_RECVV_NOINFO¶
_sctp.sctp.SCTP_RECVV_RCVINFO¶
_sctp.sctp.SCTP_RECVV_NXTINFO¶
_sctp.sctp.SCTP_RECVV_RN¶

SCTP Socket Options¶

Initialization Parameters (see RFC 6458 – section-8.1.3):

_sctp.sctp.SCTP_INIT¶
_sctp.sctp.SCTP_INITMSG¶

sctp_bindx() flags (see RFC 6458 – section-9.1):

_sctp.sctp.SCTP_BINDX_ADD_ADDR¶
_sctp.sctp.SCTP_BINDX_REM_ADDR¶

Retransmission Timeout Parameters (see RFC 6458 – section-8.1.1):

_sctp.sctp.SCTP_RTOINFO¶

Association Parameters (see RFC 6458 – section-8.1.2):

_sctp.sctp.SCTP_ASSOCINFO¶

Peer address parameters (see RFC 6458 – section-8.1.12):

_sctp.sctp.SCTP_PEER_ADDR_PARAMS¶
SPP_*

field spp_flags of struct sctp_paddrparams

Peer address information (see RFC 6458 – section-8.2.2):

_sctp.sctp.SCTP_GET_PEER_ADDR_INFO¶
_sctp.sctp.SCTP_UNCONFIRMED¶
_sctp.sctp.SCTP_ACTIVE¶
_sctp.sctp.SCTP_INACTIVE¶

Set Primary Address (see RFC 6458 – section-8.1.9):

_sctp.sctp.SCTP_PRIMARY_ADDR¶

Set Adaptation Layer Indicator (see RFC 6458 – section-8.1.10):

_sctp.sctp.SCTP_ADAPTATION_LAYER¶

Get or Set the Maximum Fragmentation Size (see RFC 6458 – section-8.1.16):

_sctp.sctp.SCTP_MAXSEG¶

Get or Set the List of Supported HMAC Identifiers (see RFC 6458 – section-8.1.17):

_sctp.sctp.SCTP_HMAC_IDENT¶

Get or Set the Active Shared Key (see RFC 6458 – section-8.1.18):

_sctp.sctp.SCTP_AUTH_ACTIVE_KEY¶

Get or Set Delayed SACK Timer (see RFC 6458 – section-8.1.19):

_sctp.sctp.SCTP_DELAYED_SACK¶

Get or Set Fragmented Interleave (see RFC 6458 – section-8.1.20):

_sctp.sctp.SCTP_FRAGMENT_INTERLEAVE¶

Set or Get the Maximum Burst (see RFC 6458 – section-8.1.24):

_sctp.sctp.SCTP_MAX_BURST¶

Set or Get the Default Context (see RFC 6458 – section-8.1.25):

_sctp.sctp.SCTP_CONTEXT¶

Set Default Send Parameters (see RFC 6458 – section-8.1.31):

_sctp.sctp.SCTP_DEFAULT_SNDINFO¶

Set Default PR-SCTP Parameters (see RFC 6458 – section-8.1.32):

_sctp.sctp.SCTP_DEFAULT_PRINFO¶

Association Status (see RFC 6458 – section-8.2.1):

_sctp.sctp.SCTP_STATUS¶

field sstat_state:
- _sctp.sctp.SCTP_CLOSED¶
- _sctp.sctp.SCTP_COOKIE_WAIT¶
- _sctp.sctp.SCTP_COOKIE_ECHOED¶
- _sctp.sctp.SCTP_ESTABLISHED¶
- _sctp.sctp.SCTP_SHUTDOWN_PENDING¶
- _sctp.sctp.SCTP_SHUTDOWN_SENT¶
- _sctp.sctp.SCTP_SHUTDOWN_RECEIVED¶
- _sctp.sctp.SCTP_SHUTDOWN_ACK_SENT¶

Get the List of Chunks the Peer Requires to Be Authenticated (see RFC 6458 – section-8.2.3):

_sctp.sctp.SCTP_PEER_AUTH_CHUNKS¶

Get the List of Chunks the Local Endpoint Requires to Be Authenticated (see RFC 6458 – section-8.2.4):

_sctp.sctp.SCTP_LOCAL_AUTH_CHUNKS¶

Get the Current Number/List of Associations (see RFC 6458 – section-8.2.5/6):

_sctp.sctp.SCTP_GET_ASSOC_NUMBER¶
_sctp.sctp.SCTP_GET_ASSOC_ID_LIST¶

Set Peer Primary Address (see RFC 6458 – section-8.3.1):

_sctp.sctp.SCTP_SET_PEER_PRIMARY_ADDR¶

Add a Chunk That Must Be Authenticated (see RFC 6458 – section-8.3.2):

_sctp.sctp.SCTP_AUTH_CHUNK¶

Set a Shared Key (see RFC 6458 – section-8.3.3):

_sctp.sctp.SCTP_AUTH_KEY¶

Deactivate/Delete a Shared Key (see RFC 6458 – section-8.3.4/5):

_sctp.sctp.SCTP_AUTH_DEACTIVATE_KEY¶
_sctp.sctp.SCTP_AUTH_DELETE_KEY¶

Sizes (sizeof()) of various structures (struct sctp_*)

_sctp.sctp.SCTP_INITMSG_CSIZE¶
_sctp.sctp.SCTP_PADDRPARAMS_CSIZE¶
_sctp.sctp.SCTP_PADDRINFO_CSIZE¶
_sctp.sctp.SCTP_RTOINFO_CSIZE¶
_sctp.sctp.SCTP_ASSOCPARAMS_CSIZE¶
_sctp.sctp.SCTP_SETPRIM_CSIZE¶
_sctp.sctp.SCTP_SETADAPTATION_CSIZE¶
_sctp.sctp.SCTP_MAXSEG_CSIZE¶
_sctp.sctp.SCTP_DELAYED_SACK_CSIZE¶
_sctp.sctp.SCTP_SNDINFO_CSIZE¶
_sctp.sctp.SCTP_DEFAULT_PRINFO_CSIZE¶
_sctp.sctp.SCTP_STATUS_CSIZE¶
_sctp.sctp.SCTP_SET_PEER_PRIMARY_ADDR_CSIZE¶
_sctp.sctp.SOCKADDR_STORAGE_CSIZE¶

Note

The C structures defined in <netinet/sctp.h> are aligned differently depending on the implementation. For example, on FreeBSD they have attribute __attribute__((packed)), while on Linux they have attribute __attribute__((packed, aligned(4))). Knowing these sizes allows module sctp to calculate the possible padding required when using module struct (see fmt property). These constants are intended for internal use only.

Miscellaneous:

_sctp.sctp.SCTP_NODELAY¶
_sctp.sctp.SCTP_AUTOCLOSE¶
_sctp.sctp.SCTP_DISABLE_FRAGMENTS¶
_sctp.sctp.SCTP_I_WANT_MAPPED_V4_ADDR¶
_sctp.sctp.SCTP_PARTIAL_DELIVERY_POINT¶
_sctp.sctp.SCTP_AUTO_ASCONF¶
_sctp.sctp.SCTP_REUSE_PORT¶
_sctp.sctp.SCTP_AUTH_HMAC_ID_SHA1¶
_sctp.sctp.SCTP_AUTH_HMAC_ID_SHA256¶

Exceptions¶

exception _sctp.sctp.SCTPError¶

Module _sctp.sctp¶

IP addresses¶

Functions¶

Creating SCTP sockets¶

Other functions¶

SCTP Socket Objects¶

Attributes¶

Methods¶

Constants¶

SCTP Socket Options¶

Exceptions¶

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