t_optmgmt(3) Library Functions Manual t_optmgmt(3)
NAME
t_optmgmt - Manages protocol options for a transport endpoint
LIBRARY
XTI Library (libxti.a)
SYNOPSIS
#include <xti.h>
int t_optmgmt(
int fd,
struct t_optmgmt *req,
struct t_optmgmt *ret) ;
STANDARDS
Interfaces documented on this reference page conform to industry standards as follows:
t_optmgmt(): XNS4.0
Refer to the standards(5) reference page for more information about industry standards and associated tags.
PARAMETERS
The following table summarizes the relevance of input and output parameters before and after t_optmgmt() is called:
Parameter Before Call After Call
-------------------------------------------
fd y n
req->opt.maxlen n n
req->opt.len y n
req->opt.buf y(y) n
req->flags y n
ret->opt.maxlen y n
ret->opt.len n y
ret->opt.buf o (o)
ret->flags n y
-------------------------------------------
Table Notes: This a meaningful parameter. The content of the object pointed to by y is meaningful. This is not a meaningful parameter.
This is an optional parameter. The content of the object pointed to by o is optional. Specifies a file descriptor returned by t_open()
function that identifies the local transport endpoint. The argument req is used to request a specific action of the provider and to send
options to the provider. The argument ret is used by the transport provider to return options and flag values to the user.
Both arguments point to a type t_optmgmt structure. This structure is used to reserve space for a transport-user options data buf-
fer that stores negotiable protocol options. The type t_optmgmt structure has the following members: Specifies a buffer for protocol
options associated with the referenced transport endpoint. The type netbuf structure pointed to by this member is defined in the
xti.h include file. This structure, which is used to define buffer parameters, has the following members: For the req argument, this
has no meaning. For the ret argument, it specifies the maximum byte length of the options buffer.
For the req argument, this specifies the number of bytes in the options. For the ret argument, it specifies the number of bytes of
options returned. For the req argument, this points to the options buffer. For the ret argument, it points to the buffer where the
options are placed.
Each option in the options buffer is of the form struct t_opthdr, possibly followed by an option value. The t_opthdr structure,
which is defined in the xti.h file, has the following members: Contains its total length (the length of the option header t_opthdr
plus the length of the option value). Identifies the XTI level or a protocol of the transport provider. Identifies the option
within the level. If t_optmgmt() is called with the action T_NEGOTIATE set, the status field of the returned options contains
information about the success or failure of the negotiation.
Each option in the input or output option buffer must start at a longword boundary. The macro OPT_NEXTHDR(pbuf, buflen, poption)
can be used for that purpose. This macro is defined in the xti.h file.
If the transport user specifies several options on input, all the options must address the same level. If any option in the options
buffer does not indicate the same level as the first option, or the level specified is unsupported, the t_optmgmt() request will
fail with the error [TBADOPT]. Some options may have been successfully negotiated when this error is detected. The transport user
can check the current status by calling t_optmgmt() with the T_CURRENT flag set. A longword (least significant bit rightmost) that
specifies the response action that must be taken by a transport provider when the t_optmgmt() function is processed. The symbolic
names for indicating various actions are defined in the xti.h include file. The flags field of req must specify one of the symbolic
names shown in the following table.
Symbolic Name Meaning
-----------------------------------------------
T_NEGOTIATE The transport user wants to
negotiate the values of the
options stored in the options
buffer. In response, the
transport provider evaluates
the options and writes accept-
able (negotiated) values to
the data buffer pointed to by
ret->opt.buf.
T_CHECK The transport user wants to
verify that the options speci-
fied in the data buffer
pointed to by req->opt.buf are
supported by the transport
provider. On return, the
transport provider writes a
ret->flags> value, which is
either T_SUCCESS or T_FAILURE.
T_DEFAULT The transport user wants to
know what the default options
supported by the transport
provider are. The transport
provider writes default data
into the options data buffer
pointed to by ret->opt.buf.
The req->opt.len parameter
must be set to 0 (zero). The
req->opt.buf member may be set
to its null value.
T_CURRENT The transport user wants to
retrieve the currently effec-
tive option values, for
options specified in
req->opt.buf. It is suffi-
cient to specify only the
t_opthdr part of an option.
The currently effective values
are then returned in
ret->opt.buf.
-----------------------------------------------
The option T_ALLOPT can only be used with t_optmgmt() and the actions T_NEGOTIATE, T_DEFAULT, and T_CURRENT. It can be used with any
supported level, and it addresses all supported options of this level. The option has no value; it consists only of a t_opthdr. In a
t_optmgmt() call, only options of one level may be addressed, so this option should not be requested together with other options.
The function returns as soon as this option has been processed.
Options are processed independently in the order they appear in the input option buffer. If an option is input multiple times, it
may be output multiple times or only once, depending on the implementation.
If the transport provider is not able to provide an interface that can support the T_NEGOTIATE or T_CHECK functions, the error
[TNOTSUPPORT] is returned.
XTI-LEVEL OPTIONS
XTI-level options are not specific for a particular transport provider. This operating system's XTI implementation supports all of the
options defined in this section.
The options described in this section are association-related. They may be negotiated in all XTI states except T_UNINIT.
The protocol level is XTI_GENERIC. The options defined for this level are listed in the following table.
Option Name Type of Option Value Legal Option Value Meaning
--------------------------------------------------------------------------------------------
XTI_DEBUG array of unsigned longs See text enable debugging
XTI_LINGER struct linger See text linger on close if data is
present
XTI_RCVBUF unsigned long size in octets receive buffer size
XTI_RCVLOWAT unsigned long size in octets receive low-water mark
XTI_SNDBUF unsigned long size in octets send buffer size
XTI_SNDLOWAT unsigned long size in octets send low-water mark
--------------------------------------------------------------------------------------------
A request for XTI_DEBUG is an absolute requirement. A request to activate XTI_LINGER is also an absolute requirement; the timeout value for
this option is not. XTI_RCVBUF, XTI_RCVLOWAT, XTI_SNDBUF, and XTI_SNDLOWAT are not absolute requirements. This option controls debugging.
Debugging is disabled if the option is specified with "no value", that is, with only an option header. Tru64 UNIX accepts a single value
for this option. A non-zero value enables socket level debugging and a zero value disables it.
The actual effects of the debugging depend upon the underlying transport provider. For example, you can set the XTI_DEBUG option
for any transport endpoint in the TCP/IP family. However, TCP is the only protocol that looks at the option. trpt can be used to
report the trace records for TCP. Other transport providers may supply utilities to process the traces. The system supplies utili-
ties to process the traces. Lingers the execution of a t_close() or close() if send data is still queued in the send buffer. The
option value specifies the linger period. If a close() or a t_close() is issued and the send buffer is not empty, the system
attempts to send the pending data within the linger period before closing the endpoint. Data still pending after the linger period
has elapsed is discarded.
Depending on the transport, t_close() or close() either block for, at maximum, the linger period, or immediately return, whereupon
the system holds the connection in existence for, at most, the linger period.
The option value consists of a structure t_linger, which is declared as shown here: struct t_linger {
long l_onoff; /* switch option on/off */
long l_linger; /* linger period in seconds */ }
The value for l_onoff is an absolute requirement. The legal values for this field are as follows: switch option off activate option
The field l_linger determines the linger period in seconds. The transport user can request the default value by setting the field to
T_UNSPEC. The default timeout value depends on the underlying transport provider; the value is often T_INFINITE. Legal values for
this field are as follows: T_UNSPEC, T_INFINITE, and all non-negative numbers.
The l_linger value is not an absolute requirement. The implementation may place upper and lower limits on this value. Requests that
fall short of the lower limit are negotiated to the lower limit.
Note that this option does not linger the execution of t_snddis(). Adjusts the internal buffer size allocated for the receive buf-
fer. The buffer size may be increased for high volume connections or decreased to limit the possible backlog of incoming data.
This request is not an absolute requirement. The implementation may place upper and lower limits on the option value. Requests that
fall short of the lower limit are negotiated to the lower limit. Sets a low-water mark in the receive buffer. The option value
gives the minimal number of bytes that must have accumulated in the receive buffer before they become visible to the transport user.
If and when the amount of accumulated receive data exceeds the low-water mark, a T_DATA event is created, an event mechanism, for
example poll( or select(, indicates the data, and the data can be read by t_rcv( or t_rcvdata().
Legal values for this field are all positive numbers.
This request is not an absolute requirement. The implementation may place upper and lower limits on the option value. Requests that
fall short of the lower limit are negotiated to the lower limit. Adjusts the internal buffer size allocated for the send buffer.
Legal values for this field are all positive numbers.
This request is not an absolute requirement. The implementation may place upper and lower limits on the option value. Requests that
fall short of the lower limit are negotiated to the lower limit. Sets a low-water mark in the send buffer. The option value gives
the minimal number of bytes that must have accumulated in the send buffer before they are sent.
Legal values for this field are all positive numbers.
This request is not an absolute requirement. The implementation may place upper and lower limits on the option value. Requests that
fall short of the lower limit are negotiated to the lower limit.
VALID STATES
The t_optmgmt() function can be called in all the transport provider states, except T_UNINIT.
DESCRIPTION
The t_optmgmt() XTI function is used in connectionless and connection-oriented transport service. The t_optmgmt() function associates spe-
cific optional parameters with a bound transport endpoint previously defined by a file descriptor returned by the t_open() function. The
t_optmgmt() function permits a transport user to retrieve, verify, or negotiate desired options with a transport provider.
A type t_optmgmt structure defined in the xti.h include file is used to specify options.
RETURN VALUE
Upon successful completion, a value of 0 (zero) is returned. Otherwise, a value of -1 is returned and t_errno is set to indicate the
error.
ERRORS
If the t_optmgmt() function fails, t_errno may be set to one of the following values: File descriptor fd does not refer to a valid trans-
port endpoint. This function was called in the wrong sequence. The specified protocol options are either of an incorrect format or con-
tain illegal information. The specified flag is invalid. The transport user does not have permission to negotiate the specified options.
The number of bytes allowed for an incoming argument is not sufficient to store the value of that argument. The information intended for
the data buffer pointed to by the ret parameter is discarded. A system error occurred during execution of the t_optmgmt() function. This
function is not supported by the underlying transport provider. This error indicates that a communication problem has been detected
between XTI and the transport provider for which there is no other suitable XTI (t_errno).
RELATED INFORMATION
Functions: t_accept(3), t_alloc(3), t_connect(3), t_getinfo(3), t_listen(3), t_open(3), t_rcvconnect(3) delim off delim off
t_optmgmt(3)