xti_sctp.3

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If the negotiated number of outgoing streams is not acceptable, it is the
responsibility of the XTI user to disconnect the transport connection.
.TP 12
.I T_SCTP_ECN
sets whether explicit congestion notification is to be supported for the
transport connection.
.TP 12
.I T_SCTP_ALI
sets which adaptation layer information is to be communicated and negotiated
for the connection.  If the negotiated adaptation layer information is less
than the capabilities sent on connection request, it is the XTI user's
responsibility to check the adaptation layer information returned in the
.I rcvcall->opt
response or in the
.I call->opt
response from a call to
.BR t_rcvconnect (3).
If the negotiated capabilities is not acceptable, it is the responsibility of
the XTI user to disconnect the transport connection.
.PP
The options of local significance that can be included in this XTI call
include (other options of local significance may also be included):
.TP 12
.I T_SCTP_HEARTBEAT_ITVL
sets the heartbeat interval to be used on all destination addresses during the
connection.
This value can be changed during the transport connection for specific
destinations using the
.I T_SCTP_HB
option to
.BR t_optmgmt (3).
.TP 12
.I T_SCTP_RTO_INITIAL
sets the initial retransmission timeout for all destinations.
This value can be changed during the transport connection for specific
destinations using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP 12
.I T_SCTP_RTO_MIN
sets the minimum retransmission timeout interval for all destinations.
This value can be changed during the transport connection for specific
destinations using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP 12
.I T_SCTP_RTO_MAX
sets the maximum retransmission timeout interval for all destinations.
This value can be changed during the transport connection for specific
destinations using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP 12
.I T_SCTP_PATH_MAX_RETRANS
sets the maximum number of times that a retransmission will be directed at a
destination adress until the destination address is deemed inactive.
This value can be changed during the transport connection for specific
destinations using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP 12
.I T_SCTP_MAX_INIT_RETRIES
sets the maximum number of INIT retransmissions that will be performed until
the destination transport address is abandoned.  When multiple transport
endpoint addresses are provided to
.BR t_connect (3),
each destination transport address will be tried this many times in turn.
.PP
If the provider indicates that connection data can be included in the response
to
.BR t_getinfo (3),
the XTI user can provide connection data in the
.I sndcall->udata
parameter.
.PP
For information that may be returned in the
.I rcvcall
argument to
.BR t_connect (3),
see the considerations for the
.I call
argument to
.I \(lqt_rcvconnect\(rq
XTI library call, below.
.\"
.\"
.SS t_getinfo\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_connect (3)
with the additional considerations described here.
.PP
.TP 12
.I addr
For compatibility with the
.BR sockets (3)
library,
.B SCTP
uses a
.B sockaddr_in
structured address.  However, a number of XTI library calls support multiple
.B sockaddr_in
address to be specified in a single call.  This size will be an integer multiple of the
size of the
.B sockaddr_in
structure size, indicating how many
.B sockaddr_in
structures can be included in a single address specification.
.TP 12
.I options
The maximum size of options is provider specific.  The
.B OpenSS7
SCTP implementation
.RB ( sctp (4))
returns the maximum size of an options structure containing all SCTP options.
.TP 12
.I tsdu
The maximum size of a transport service data unit.  For SCTP this is the
maximum size of a message, considering that it may be fragmented and sent in
multiple DATA chunks.  For
.BR sctp (4)
this value could be
.BR T_INFINITE .
SCTP
.[
RFC 2960
.]
has some limitations resulting from stream blockage due to large messages that
need to be fragmented and sent in multiple chunks.  Some implementations may
want to restrict the maximum size of a TSDU to something smaller for this
purpose.
.TP 12
.I etsdu
.B SCTP
supports the concept of expedited data as data that is sent unordered.  SCTP
conforming transport provides will not return
.B T_INVALID
for this field.  The maximum ETSDU size is subject to the same considerations
as the TSDU size above.  Some implementations may wish to restrict the size of
the ETSDU to smaller than the TSDU because unordered data causes more problems
with stream blocking due to fragmentation in SCTP.
.[
RFC 2960
.]
.TP 12
.I connect
SCTP supports the concept of connection data.  Although SCTP also supports
sending the first fragments of a TSDU or ETSDU with the COOKIE-ECHO or
COOKIE-ACK chunks, and subsequent fragements later, this value represents the
maximum size of a TSDU that can be completely contained in the COOKIE-ECHO or
COOKIE-ACK chunks.  This value will typically be substantially less than the
TSDU size above.  Implementations that do not support sending of DATA chunks
bundled with the COOKIE-ECHO or COOKIE-ACK may return
.B T_INVALID
for this field.
.sp
(Note that there is no way in TPI
.[
TPI Revision 2.0.0
.]
to send a
.BR T_CONNECT_REQ (7)
indicated expedited data.  Therefore, it is only possible to send a TSDU with
.BR t_connect (3)
in
.BR xti (3).
.TP 12
.I discon
Although SCTP supports orderly release, SCTP does not support the concept of
disconnection data.  SCTP conforming transport providers will always return
.B T_INVALID
in this field.
.TP 12
.I servtype
SCTP supports only connection-oriented modes with orderly release.  SCTP
conforming transport service providers will return
.B T_COTS_ORD
whenever the SCTP implementation supports orderly release (i.e. SHUTDOWN and
SHUTDOWN-ACK).
SCTP conforming transport service providers may return
.B T_COTS
if the SCTP implementation does not support orderly release.
SCTP conforming transport service providers will not return
.BR T_CLTS .
.TP 12
.I flags
SCTP support orderly release but does not support orderly release data and
does not support sending null data.  SCTP conforming transport providers will
not return
.BR T_ORDRELDATA " or " T_SNDZERO
flags.
SCTP conforming transport service providers may return the
.B XPG4_1
flag.
.\"
.\"
.SS t_listen\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_listen (3)
with the additional considerations described here.
.PP
Some SCTP options of end-to-end significance should be set before a call to
.BR t_listen (3),
using
.BR t_optmgmt (3),
are as follows:
.TP 12
.I T_SCTP_CKSUM_TYPE
set the type of checksum to be performed on all packets for all connections
indicated on this transport endpoint.  This option is useful if the listening
XTI user is aware that the connecting transport endpoints only support the
older Adler 32 checksum.
.TP 12
.I T_SCTP_MAC_TYPE
sets the message authentication digest algorithm that will be used when
signing cookies that are returned to transport endpoints generating connection
indications on this transport endpoint.  This option is useful if the
listening XTI user wishes to forego or select the security/performance
trade-off associated with the generation of cookies on the transport endpoint.
.TP 12
.I T_SCTP_COOKIE_LIFE
sets the lifetime of cookies generated by the listening transport endpoint.
This also sets the interval of re-keying of message authentication digests.
This is useful if the listening transport endpoint is aware of the transit
delays associated with forming connections to the listening transport endpoint
and wishes to tighten or loosen the security associated with cookie lifetimes
and re-keying of message authentication digests.
.TP 12
.I T_SCTP_COOKIE_INC
sets the cookie increment that will be applied to connecting transport
endpoints requesting cookie preservation.
.TP 12
.I T_SCTP_THROTTLE_ITVL
sets the throttle interval for throttling connection attempts on the listening
transport endpoint.
.PP
In addition, any of the options described under
.BR t_accept (3),
above, may be set with
.BR t_optmgmt (3)
before the call to
.BR t_listen (3).
.PP
When an incoming connection is indicated, the calling address indicated in the
.I call->addr
argument can contain multiple
.B sockaddr_in
structures, each representing a multi-homed IP transport address from which
the connection is requested.  This first address in the list is always the
source address of the COOKIE-ECHO packet.  Each address in the array will have
the same
.I call->addr[i].sin_family
and
.I call->addr[i].sin_port
fields.
.PP
When an incoming connection is indicated, the options indicated in the
.I call->opt
argument that are of end-to-end significance are as follows:
.TP 12
.I T_SCTP_CKSUM_TYPE
indicates the checksum type that was used for the COOKIE-ECHO packet.  This
value is auto-detected.  If this checksum type is unacceptable to the XTI user,
the XTI user should refuse the connection indication using
.BR t_snddis (3),
with the indicated sequence number.
.TP 12
.I T_SCTP_ISTREAMS
indicates the number of incoming streams requested by the peer.  If this value
is too high, it may be adjusted using this option to the
.BR t_accept (3)
call.  This value cannot be adjusted upward.  If the value is too low, the
XTI user should refuse the connection indication using
.BR t_snddis (3),
with the indicated sequence number.
.TP 12
.I T_SCTP_OSTREAMS
indicates the maximum number of outgoing streams supported by the peer.  If
this value is too high, it may be adjusted downward using this option to the
.BR t_accept (3)
call.  This value cannot be adjusted upward.  If the value is too low, the
XTI user should refuse the connection indication using
.BR t_snddis (3),
with the indicated sequence number.
.TP 12
.I T_SCTP_ECN
indicates whether the peer supports explicit congestion notification.  The
peer cannot be compelled to use explicit congestion notification.  If explicit
congestion notification is required but not indicated, it is the XTI user's
responsibility to refuse the transport connection using
.BR t_snddis (3)
with the indicated sequence number.  Whether this transport endpoint supports
explicit congestion notification or not can be specified using this option to
the
.BR t_accept (3)
call accepting the connection indication.
.TP 12
.I T_SCTP_ALI
indicates whether the peer supports adaptation layer information and extension
capabilities to the SCTP protocol.  If capabilities are required that are not
indicated, it is the XTI user's responsibility to refuse the transport
connection using
.BR t_snddis (3)
with the indicated sequence number.  Whether this transport endpoint supports
adaptation layer information and which capabilities it supports can be
specified using this option to the
.BR t_accept (3)
call accepting the connection indication.
.PP
If the SCTP peer provided connection data bundled with the COOKIE-ECHO, the
data will be indicated in the
.I call->udata
parameter.
.\"
.\"
.SS t_open\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_open (3)
with the additional considerations described here.
The information returned in the
.I info
parameter to this XTI call has the same considerations as the
.I info
parameter returned in the call to
.BR t_getinfo (3),
described above.
.\"
.\"
.SS t_optmgmt\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_optmgmt (3)
with the additional considerations described here.
The options that may be set, retrieved or negotiated using this XTI library
call are described under
.IR \(lqOPTIONS\(rq ,
above.
.\"
.\"
.SS t_rcvconnect\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_rcvconnect (3)
with the additional considerations described here.
.PP
Multiple addresses.
.PP
.IR T_SCTP_HEARTBEAT_ITVL ,
.IR T_SCTP_RTO_INITIAL ,
.IR T_SCTP_RTO_MIN ,
.IR T_SCTP_RTO_MAX ,
.IR T_SCTP_PATH_MAX_RETRANS ,
.IR T_SCTP_CKSUM_TYPE ,
.IR T_SCTP_MAC_TYPE ,
.IR T_SCTP_COOKIE_LIFE ,
.IR T_SCTP_COOKIE_INC ,
.IR T_SCTP_THROTTLE_ITVL ,
.IR T_SCTP_ISTREAMS ,
.IR T_SCTP_OSTREAMS ,
.IR T_SCTP_ECN ,
.IR T_SCTP_ALI ,
.IR T_SCTP_MAX_INIT_RETRIES ,
.\"
.\"
.SS t_rcvdis\fR(3)
.PP
SCTP supports this XTI library call as described in
.BR t_rcvdis (3)
with the additional considerations described here.
.PP
SCTP does not support disconnection data and the
.I dis->udata
parameter will always be empty.
.PP
.I dis->reason
will either be a negative UNIX\(rg error code, or an SCTP protocol-specific error code
as follows:
.TP 12
.I T_SCTP_CAUSE_INVALID_STR
a DATA chunk was received that contained an invalid stream identifier.
.TP 12
.I T_SCTP_CAUSE_MISSING_PARM
a control chunk was missing a mandatory parameter.
.TP 12
.I T_SCTP_CAUSE_STALE_COOKIE
the cookie went stale before a transport connection could be formed.
.TP 12
.I T_SCTP_CAUSE_NO_RESOURCE
there was insufficient resource to form the transport connection.
.TP 12
.I T_SCTP_CAUSE_BAD_ADDRESS
a provided destination transport address was invalid.
.TP 12
.I T_SCTP_CAUSE_BAD_CHUNK_TYPE
an unrecognized chunk type was received.
.TP 12
.I T_SCTP_CAUSE_INVALID_PARM
an invalid parameter type was received.
.TP 12
.I T_SCTP_CAUSE_BAD_PARM
a parameter containing an invalid value was received.
.TP 12
.I T_SCTP_CAUSE_NO_DATA
a DATA chunk was received that contained no data.
.TP 12
.I T_SCTP_CAUSE_SHUTDOWN
a cookie was received while shutting down.
.TP 12
.I T_SCTP_CAUSE_NEW_ADDR
restart of an association with a new address.
.TP 12
.I T_SCTP_CAUSE_USER_INITIATED
user initiated abort.
.TP 12
.I T_SCTP_CAUSE_PROTO_VIOLATION
protocol violation.
.TP 12
.I T_SCTP_CAUSE_LAST_ADDR
request to delete last IP address for the transport connection.
.TP 12
.I T_SCTP_CAUSE_RES_SHORTAGE
operation was refused due to resource shortage.
.TP 12
.I T_SCTP_CAUSE_SOURCE_ADDR
request to delete a source IP address.
.TP 12
.I T_SCTP_CAUSE_ILLEGAL_ASCONF
association aborted due to illegal ASCONF