xti_sctp.3.man

This a separate release of the OpenSS7 X/Open XTI/TLI library, TLI modules (timod, tirdwr) and the I

.TP
.I XTI_SNDLOWAT
.TP
.I T_IP_REUSEADDR
.TP
.I T_IP_DONTROUTE
.TP
.I T_IP_BROADCAST
.TP
.I T_SCTP_HEARTBEAT_ITVL
sets the heartbeat interval to be used on all destination addresses during the
connection.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
This value may be changed during the transport connection using the
.I T_SCTP_HB
option to
.BR t_optmgmt (3).
.TP
.I T_SCTP_RTO_INITIAL
sets the initial retransmission timeout for all destinations.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
This value may be changed during the transport connection using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP
.I T_SCTP_RTO_MIN
sets the minimum retransmission timeout interval for all destinations.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
This value may be changed during the transport connection using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP
.I T_SCTP_RTO_MAX
sets the maximum retransmission timeout interval for all destinations.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
This value may be changed during the transport connection using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.TP
.I T_SCTP_PATH_MAX_RETRANS
sets the maximum number of times that a retransmission will be directed at a
destination address until the destination address is deemed inactive.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
This value may be changed during the transport connection using the
.I T_SCTP_RTO
option to
.BR t_optmgmt (3).
.I T_SCTP_MAX_INIT_RETRIES
sets the maximum number of COOKIE-ACK retransmissions that will be performed
until the destination transport address is abandoned.
This value is
.I read-only
in other than the
.BR T_IDLE " or " T_OUTCON
states.
This value can be changed for specific connection by providing this option to the
.BR t_accept (3).
.PP
If the provider indicates that connect data can be included in the response to
.BR t_getinfo (3),
the XTI/TLI user can provide connection data in the
.I call->udata
parameter.
.\"
.\"
.SS t_bind\fR(3)
.PP
SCTP supports this XTI/TLI library call as described in
.BR t_bind (3),
with the additional considerations described here.
.PP
When the XTI/TLI user provides a transport endpoint address in
.IR req->addr ,
the address to bind can contain multiple
.B sockaddr_in
structures, each representing a local IP address to which to bind a multi-homed
SCTP transport endpoint.
Each address in the array must have the same
.I req->addr[i].sin_family
and
.I req->addr[i].sin_port
value.
.PP
When the SCTP transport service provider returns the bound address in
.IR ret->addr ,
the address bound can contain multiple
.B sockaddr_in
structures, each representing a bound local IP address.  The SCTP conforming
transport service provider will return the same values in each
.I ret->addr[i].sin_family
and
.I ret->addr[i].sin_port
fields.
.PP
The
.BR INET (4)
implementation treats port number zero (0) as a request to bind to any
unused port.  Other than that value, the
.I req->addr.sin_port
part of the binding is specific.  The
.I req->addr.sin_addr.in_addr
part of the binding can represent a single IP address or a wildcard binding to
an address that could represent multiple IP addresses that are legal for the
host
.RB ( INADDR_ANY ).
.PP
Under recent versions of
.BR INET (4),
.BR t_bind (3)
called with a
.B NULL
.I req
argument is equivalent to binding to a wildcard port number with a wildcard IP
address.
.PP
Under
.BR INET (4),
when bound to a wildcard port or IP address, assignment of a specific port
number and IP address can be deferred until an incoming or outgoing connection
is initiated.  Under these situations, any address returned in the
.I ret
argument to
.BR t_bind (3)
or the
.I loc
argument to
.BR t_getprotaddr (3)
will return the wildcard address and port number instead of an assigned
list of addresses and port number.
Only once a connection has been established will the local address returned by
.BR t_getprotaddr (3)
be assured to be an assigned address list rather than a wildcard address.
.\"
.\"
.SS t_close\fR(3)
.PP
SCTP supports this XTI/TLI library call as described in
.BR t_close (3)
without modifications.
.PP
The
.BR t_close (3)
call will result in a
.BR close (2)
call on the descriptor of this XTI/TLI communication endpoint.  If there are no
other descriptors in this process which reference the communications endpoint,
the
.BR close (2)
call will perform an orderly connection termination according to the rules of
a TCP CLOSE call on this transport endpoint as specified in the standards
.I RFC 793
.[
rfc 793
.]
and
.IR "RFC 1122" .
.[
rfc 1122
.]
If the
.B XTI_LINGER
option is supported and is used to enable the linger option, the linger time
will affect the time an implementation lingers in the execution of
.BR t_close (3)
or
.BR close (2).
A linger time of zero (0) specified with the
.B XTI_LINGER
option may cause an abortive release of a TCP connection, resulting in lost
data.
.\"
.\"
.SS t_connect\fR(3)
.PP
SCTP supports this XTI/TLI library call as described in
.BR t_connect (3),
with the additional considerations described here.
.PP
The
.I sndcall->addr
structure specifies the remote socket.  In the present version, the returned
address set in
.I rcvcall->addr
will have the same value.  Note that the peer SCTP, and not the peer transport
user, confirms the connection.
.PP
When the XTI/TLI user provides a transport endpoint address to which to connect in
.IR sndcall->addr ,
the address can be an array of
.B sockaddr_in
structures, each indicating a remote address for the endpoint to which to
connect.
Only one address is necessary to successfully form a multi-homed transport
connection; however, if additional addresses are provided, the transport
connection is initialized in a more secure and reliable fashion.
.PP
SCTP provides a number of options, described in
.IR \(lqOPTIONS\(rq ,
above, that may be included in this XTI/TLI call
in the
.I sndcall->opt
parameter to change local ad end-to-end characteristics of the transport
endpoint accepting the connection.
The options of end-to-end significance that can be included in this XTI/TLI library
call are:
.TP
.I T_SCTP_CKSUM_TYPE
set the type of checksum to be performed on all packets for the connection.
This option is useful if the connecting XTI/TLI user is aware that the destination
transport endpoint only supports the older Adler 32 checksum.
.TP
.I T_SCTP_ISTREAMS
set the maximum number of incoming streams for the connection.  The peer must
respect this value and negotiate the number of incoming streams to be less
than or equal to this value or the transport connection will fail.
.TP
.I T_SCTP_OSTREAMS
set the requested number of outgoing streams for the connection.  The peer may
negotiate a smaller number of outgoing streams depending on its maximum
incoming stream requirements.  It is the XTI/TLI user's responsibility to check
the number of outgoing streams in the
.I rcvcall->opt
response or in the
.I call->opt
response from a call to
.BR t_rcvconnect (3).
If the negotiated number of outgoing streams is not acceptable, it is the
responsibility of the XTI/TLI user to disconnect the transport connection.
.TP
.I T_SCTP_ECN
sets whether explicit congestion notification is to be supported for the
transport connection.
.TP
.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/TLI 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/TLI user to disconnect the transport connection.
.PP
The options of local significance that can be included in this XTI/TLI call
include (other options of local significance may also be included):
.TP
.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
.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
.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
.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
.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
.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/TLI 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/TLI library call, below.
.\"
.\"
.SS t_getinfo\fR(3)
.PP
SCTP supports this XTI/TLI library call as described in
.BR t_connect (3)
with the additional considerations described here.
.PP
.TP \w'servtype\(em'u
.I addr
For compatibility with the
.BR sockets (3)
library,
.B SCTP
uses a
.B sockaddr_in
structured address.  However, a number of XTI/TLI 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
.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
.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
.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
.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
.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
.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
.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/TLI library call as described in
.BR t_listen (3)
with the additional considerations described here.
.PP
Upon successful return
.BR t_listen (3)
indicates an existing connection and not a connection indication.  Since user
data cannot be exchanged during the connection establishment phase,
.I call->udata.maxlen
must be set to zero (0) before the call to
.BR t_listen (3).
The
.I call->addr
structure contains the remote calling socket.
.PP
.B XTI-SCTP
does not support the same semantics with regard to indication of
connections, acceptance of indicated connections, and ne