path: root/usr/src/man/man3nsl/t_optmgmt.3nsl

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.TH T_OPTMGMT 3NSL "May 7, 1998"
.SH NAME
t_optmgmt \- manage options for a transport endpoint
.SH SYNOPSIS
.LP
.nf
#include <xti.h>



\fBint\fR \fBt_optmgmt\fR(\fBint\fR \fIfd\fR, \fBconst struct t_optmgmt *\fR\fIreq\fR, \fBstruct t_optmgmt *\fR\fIret\fR);
.fi

.SH DESCRIPTION
.sp
.LP
This routine is part of the \fBXTI\fR interfaces which evolved from the
\fBTLI\fR interfaces. \fBXTI\fR represents the future evolution of these
interfaces. However, \fBTLI\fR interfaces are supported for compatibility. When
using a \fBTLI\fR routine that has the same name as an \fBXTI\fR routine, the
\fBtiuser.h\fR header file must be used.  Refer to the  \fBTLI\fR
\fBCOMPATIBILITY\fR section for a description of differences between the two
interfaces.
.sp
.LP
The \fBt_optmgmt()\fR function enables a transport user to retrieve, verify or
negotiate protocol options with the transport provider. The argument \fIfd\fR
identifies a transport endpoint.
.sp
.LP
The \fIreq\fR and \fIret\fR arguments point to a \fBt_optmgmt\fR structure
containing the following members:
.sp
.in +2
.nf
\fBstruct netbuf opt;
t_scalar_t    flags;\fR
.fi
.in -2

.sp
.LP
The \fIopt\fR field identifies protocol options and the \fIflags\fR field is
used to specify the action to take with those options.
.sp
.LP
The options are represented by a \fBnetbuf\fR structure in a manner similar to
the address in \fBt_bind\fR(3NSL). The argument \fIreq\fR is used to request a
specific action of the provider and to send options to the provider.  The
argument \fIlen\fR specifies the number of bytes in the options, \fIbuf\fR
points to the options buffer, and \fImaxlen\fR has no meaning for the \fIreq\fR
argument. The transport provider may return options and flag values to the user
through \fIret\fR. For \fIret\fR, \fImaxlen\fR specifies the maximum size of
the options buffer and \fIbuf\fR points to the buffer where the options are to
be placed. If  \fImaxlen\fR in  \fIret\fR is set to zero, no options values are
returned. On return, \fIlen\fR specifies the number of bytes of options
returned. The value in \fImaxlen\fR has no meaning for the \fIreq\fR argument,
but must be set in the \fIret\fR argument to specify the maximum number of
bytes the options buffer can hold.
.sp
.LP
Each option in the options buffer is of the form \fBstruct t_opthdr\fR possibly
followed by an option value.
.sp
.LP
The \fIlevel\fR field of \fBstruct t_opthdr\fR identifies the XTI level or a
protocol of the transport provider. The \fIname\fR field identifies the option
within the level, and \fIlen\fR contains its total length; that is, the length
of the option header \fBt_opthdr\fR plus the length of the option value.  If
\fBt_optmgmt()\fR is called with the action  \fBT_NEGOTIATE\fR set, the
\fIstatus\fR field of the returned options contains information about the
success or failure of a negotiation.
.sp
.LP
Several options can be concatenated. The option user has, however to ensure
that each options header and value part starts at a boundary appropriate for
the architecture\(hyspecific alignment rules. The macros
\fBT_OPT_FIRSTHDR\fR(nbp), \fBT_OPT_NEXTHDR\fR (nbp,tohp),
\fBT_OPT_DATA\fR(tohp) are provided for that purpose.
.sp
.ne 2
.na
\fB\fBT_OPT_DATA(nhp)\fR \fR
.ad
.RS 29n
If argument is a pointer to a \fBt_opthdr\fR structure, this macro returns an
unsigned character pointer to the data associated with the \fBt_opthdr\fR.
.RE

.sp
.ne 2
.na
\fB\fBT_OPT_NEXTHDR(nbp,\fR \fBtohp)\fR \fR
.ad
.RS 29n
If the first argument is a pointer to a netbuf structure associated with an
option buffer and second argument is a pointer to a \fBt_opthdr\fR structure
within that option buffer, this macro returns a pointer to the next
\fBt_opthdr\fR structure or a null pointer if this \fBt_opthdr\fR is the last
\fBt_opthdr\fR in the option buffer.
.RE

.sp
.ne 2
.na
\fB\fBT_OPT_FIRSTHDR(tohp)\fR \fR
.ad
.RS 29n
If the argument is a pointer to a \fBnetbuf\fR structure associated with an
option buffer, this macro returns the pointer to the first \fBt_opthdr\fR
structure in the associated option buffer, or a null pointer if there is no
option buffer associated with this \fBnetbuf\fR or if it is not possible or the
associated option buffer is too small to accommodate even the first aligned
option header.
.sp
\fBT_OPT_FIRSTHDR\fR is useful for finding an appropriately aligned start of
the option buffer. \fBT_OPT_NEXTHDR\fR is useful for moving to the start of the
next appropriately aligned option in the option buffer. Note that
\fBOPT_NEXTHDR\fR is also available for backward compatibility requirements.
\fBT_OPT_DATA\fR is useful for finding the start of the data part in the option
buffer where the contents of its values start on an appropriately aligned
boundary.
.sp
If the transport user specifies several options on input, all options must
address the same level.
.sp
If any option in the options buffer does not indicate the same level as the
first option, or the level specified is unsupported, then the \fBt_optmgmt()\fR
request will fail with \fBTBADOPT\fR. If the error is detected, some options
have possibly been successfully negotiated. The transport user can check the
current status by calling \fBt_optmgmt()\fR with the  \fBT_CURRENT\fR flag set.
.sp
The \fIflags\fR field of \fIreq\fR must specify one of the following actions:
.RE

.sp
.ne 2
.na
\fB\fBT_NEGOTIATE\fR \fR
.ad
.RS 29n
This action enables the transport user to negotiate option values.
.sp
The user specifies the options of interest and their values in the buffer
specified by \fIreq\(->opt.buf\fR and \fIreq\(->opt.len\fR. The negotiated
option values are returned in the buffer pointed to by \fIret->opt.buf\fR. The
\fIstatus\fR field of each returned option is set to indicate the result of the
negotiation. The value is  \fBT_SUCCESS\fR if the proposed value was
negotiated, \fBT_PARTSUCCESS\fR if a degraded value was negotiated,
\fBT_FAILURE\fR if the negotiation failed (according to the negotiation rules),
\fBT_NOTSUPPORT\fR if the transport provider does not support this option or
illegally requests negotiation of a privileged option, and  \fBT_READONLY\fR if
modification of a read-only option was requested. If the status is
\fBT_SUCCESS,\fR \fBT_FAILURE,\fR \fBT_NOTSUPPORT\fR or  \fBT_READONLY,\fR the
returned option value is the same as the one requested on input.
.sp
The overall result of the negotiation is returned in \fIret\(->flags\fR.
.sp
This field contains the worst single result, whereby the rating is done
according to the order  \fBT_NOTSUPPORT,\fR \fBT_READONLY,\fR \fBT_FAILURE,\fR
\fBT_PARTSUCCESS,\fR \fBT_SUCCESS.\fR The value  \fBT_NOTSUPPORT\fR is the
worst result and  \fBT_SUCCESS\fR is the best.
.sp
For each level, the option  \fBT_ALLOPT\fR can be requested on input. No value
is given with this option; only the \fBt_opthdr\fR part is specified. This
input requests to negotiate all supported options of this level to their
default values. The result is returned option by option in
\fIret\(->opt.buf\fR. Note that depending on the state of the transport
endpoint, not all requests to negotiate the default value may be successful.
.RE

.sp
.ne 2
.na
\fB\fBT_CHECK\fR \fR
.ad
.RS 29n
This action enables the user to verify whether the options specified in
\fIreq\fR are supported by the transport provider.If an option is specified
with no option value (it consists only of a \fBt_opthdr\fR structure), the
option is returned with its \fIstatus\fR field set to  \fBT_SUCCESS\fR if it is
supported,  \fBT_NOTSUPPORT\fR if it is not or needs additional user
privileges, and  \fBT_READONLY\fR if it is read-only (in the current XTI
state). No option value is returned.
.sp
If an option is specified with an option value, the \fIstatus\fR field of the
returned option has the same value, as if the user had tried to negotiate this
value with  \fBT_NEGOTIATE.\fR If the status is  \fBT_SUCCESS\fR,
\fBT_FAILURE\fR, \fBT_NOTSUPPORT\fR or  \fBT_READONLY\fR, the returned option
value is the same as the one requested on input.
.sp
The overall result of the option checks is returned in \fIret\(->flags\fR. This
field contains the worst single result of the option checks, whereby the rating
is the same as for  \fBT_NEGOTIATE\fR .
.sp
Note that no negotiation takes place. All currently effective option values
remain unchanged.
.RE

.sp
.ne 2
.na
\fB\fBT_DEFAULT\fR \fR
.ad
.RS 29n
This action enables the transport user to retrieve the default option values.
The user specifies the options of interest in \fIreq\(->opt.buf\fR. The option
values are irrelevant and will be ignored; it is sufficient to specify the
\fBt_opthdr\fR part of an option only. The default values are then returned in
\fIret\(->opt.buf\fR.
.sp
The \fIstatus\fR field returned is  \fBT_NOTSUPPORT\fR if the protocol level
does not support this option or the transport user illegally requested a
privileged option,  \fBT_READONLY\fR if the option is read-only, and set to
\fBT_SUCCESS\fR in all other cases. The overall result of the request is
returned in \fIret\(->flags\fR. This field contains the worst single result,
whereby the rating is the same as for  \fBT_NEGOTIATE.\fR
.sp
For each level, the option  \fBT_ALLOPT\fR can be requested on input. All
supported options of this level with their default values are then returned. In
this case, \fIret\(->opt.maxlen\fR must be given at least the value
\fIinfo\(->options\fR before the call. See \fBt_getinfo\fR(3NSL) and
\fBt_open\fR(3NSL).
.RE

.sp
.ne 2
.na
\fB\fBT_CURRENT\fR\fR
.ad
.RS 29n
This action enables the transport user to retrieve the currently effective
option values. The user specifies the options of interest in
\fIreq\(->opt.buf\fR. The option values are irrelevant and will be ignored; it
is sufficient to specifiy the \fBt_opthdr\fR part of an option only. The
currently effective values are then returned in \fIreq\(->opt.buf\fR.
.sp
The \fIstatus\fR field returned is  \fBT_NOTSUPPORT\fR if the protocol level
does not support this option or the transport user illegally requested a
privileged option, T_READONLY if the option is read-only, and set to
\fBT_SUCCESS\fR in all other cases. The overall result of the request is
returned in \fIret\(->flags\fR. This field contains the worst single result,
whereby the rating is the same as for  \fBT_NEGOTIATE.\fR
.sp
For each level, the option  \fBT_ALLOPT\fR can be requested on input. All
supported options of this level with their currently effective values are then
returned.
.sp
The option  \fBT_ALLOPT\fR can only be used with \fBt_optmgmt()\fR and the
actions  \fBT_NEGOTIATE,\fR \fBT_DEFAULT\fR and  \fBT_CURRENT.\fR It can be
used with any supported level and addresses all supported options of this
level.  The option has no value; it consists of a \fBt_opthdr\fR only.  Since
in a \fBt_optmgmt()\fR call only options of one level may be addressed, this
option should not be requested together with other options. The function
returns as soon as this option has been processed.
.sp
Options are independently processed in the order they appear in the input
option buffer. If an option is multiply input, it depends on the implementation
whether it is multiply output or whether it is returned only once.
.sp
Transport providers may not be able to provide an interface capable of
supporting  \fBT_NEGOTIATE\fR and/or  \fBT_CHECK\fR functionalities. When this
is the case, the error \fBTNOTSUPPORT\fR is returned.
.sp
The function \fBt_optmgmt()\fR may block under various circumstances and
depending on the implementation. The function will block, for instance, if the
protocol addressed by the call resides on a separate controller. It may also
block due to flow control constraints; that is, if data sent previously across
this transport endpoint has not yet been fully processed. If the function is
interrupted by a signal, the option negotiations that have been done so far may
remain valid. The behavior of the function is not changed if  \fBO_NONBLOCK\fR
is set.
.RE

.SH RETURN VALUES
.sp
.LP
Upon successful completion, a value of  \fB0\fR is returned. Otherwise, a value
of \(mi1 is returned and \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
.sp
.LP
ALL - apart from \fBT_UNINIT\fR.
.SH ERRORS
.sp
.LP
On failure, \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTBADF\fR\fR
.ad
.RS 15n
The specified file descriptor does not refer to a transport endpoint.
.RE

.sp
.ne 2
.na
\fB\fBTBADFLAG\fR\fR
.ad
.RS 15n
An invalid flag was specified.
.RE

.sp
.ne 2
.na
\fB\fBTBADOPT\fR\fR
.ad
.RS 15n
The specified options were in an incorrect format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTBUFOVFLW\fR\fR
.ad
.RS 15n
The number of bytes allowed for an incoming argument \fI(maxlen)\fR is greater
than  \fB0\fR but not sufficient to store the value of that argument. The
information to be returned in \fIret\fR will be discarded.
.RE

.sp
.ne 2
.na
\fB\fBTNOTSUPPORT\fR\fR
.ad
.RS 15n
This action is not supported by the transport provider.
.RE

.sp
.ne 2
.na
\fB\fBTOUTSTATE\fR\fR
.ad
.RS 15n
The communications endpoint referenced by  \fIfd\fR is not in one of the states
in which a call to this function is valid.
.RE

.sp
.ne 2
.na
\fB\fBTPROTO\fR\fR
.ad
.RS 15n
This error indicates that a communication problem has been detected between XTI
and the transport provider for which there is no other suitable XTI error
\fB(t_errno)\fR.
.RE

.sp
.ne 2
.na
\fB\fBTSYSERR\fR\fR
.ad
.RS 15n
A system error has occurred during execution of this function.
.RE

.SH TLI COMPATIBILITY
.sp
.LP
The \fBXTI\fR and \fBTLI\fR interface definitions have common names but use
different header files. This, and other semantic differences between the two
interfaces are described in the subsections below.
.SS "Interface Header"
.sp
.LP
The \fBXTI\fR interfaces use the header file, \fBxti.h\fR. \fBTLI\fR interfaces
should \fInot\fR use this header.  They should use the header:
.sp
.in +2
.nf
#include <tiuser.h>
.fi
.in -2

.SS "Error Description Values"
.sp
.LP
The \fBt_errno\fR value \fBTPROTO\fR can be set by the \fBXTI\fR interface but
not by the \fBTLI\fR interface.
.sp
.LP
The \fBt_errno\fR values that this routine can return under different
circumstances than its \fBXTI\fR counterpart are \fBTACCES\fR and
\fBTBUFOVFLW\fR.
.sp
.ne 2
.na
\fB\fBTACCES\fR \fR
.ad
.RS 14n
can be returned to indicate that the user does not have permission to negotiate
the specified options.
.RE

.sp
.ne 2
.na
\fB\fBTBUFOVFLW\fR \fR
.ad
.RS 14n
can be returned even when the \fBmaxlen\fR field of the corresponding buffer
has been set to zero.
.RE

.SS "Option Buffers"
.sp
.LP
The format of the options in an \fBopt\fR buffer is dictated by the transport
provider. Unlike the \fBXTI\fR interface, the \fBTLI\fR interface does not fix
the buffer format. The macros \fBT_OPT_DATA,\fR \fBT_OPT_NEXTHDR,\fR and
\fBT_OPT_FIRSTHDR\fR described for \fBXTI\fR are not available for use by TLI
interfaces.
.SS "Actions"
.sp
.LP
The semantic meaning of various action values for the \fBflags\fR field of
\fIreq\fR differs between the \fBTLI\fR and \fBXTI\fR interfaces. \fBTLI\fR
interface users should heed the following descriptions of the actions:
.sp
.ne 2
.na
\fB\fBT_NEGOTIATE\fR \fR
.ad
.RS 16n
This action enables the user to negotiate the values of the options specified
in \fIreq\fR with the transport provider. The provider will evaluate the
requested options and negotiate the values, returning the negotiated values
through \fIret\fR.
.RE

.sp
.ne 2
.na
\fB\fBT_CHECK\fR \fR
.ad
.RS 16n
This action enables the user to verify whether the options specified in
\fIreq\fR are supported by the transport provider. On return, the \fBflags\fR
field of \fIret\fR will have either \fBT_SUCCESS\fR or \fBT_FAILURE\fR set to
indicate to the user whether the options are supported. These flags are only
meaningful for the \fBT_CHECK\fR request.
.RE

.sp
.ne 2
.na
\fB\fBT_DEFAULT\fR \fR
.ad
.RS 16n
This action enables a user to retrieve the default options supported by the
transport provider into the \fBopt\fR field of \fIret\fR. In \fIreq\fR, the
\fBlen\fR field of \fBopt\fR must be zero and the \fBbuf\fR field may be
\fINULL\fR.
.RE

.SS "Connectionless Mode"
.sp
.LP
If issued as part of the connectionless mode service, \fBt_optmgmt()\fR may
block due to flow control constraints. The function will not complete until the
transport provider has processed all previously sent data units.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7)  for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
MT Level	Safe
.TE

.SH SEE ALSO
.sp
.LP
.BR close (2),
.BR poll (2),
.BR select (3C),
.BR t_accept (3NSL),
.BR t_alloc (3NSL),
.BR t_bind (3NSL),
.BR t_close (3NSL),
.BR t_connect (3NSL),
.BR t_getinfo (3NSL),
.BR t_listen (3NSL),
.BR t_open (3NSL),
.BR t_rcv (3NSL),
.BR t_rcvconnect (3NSL),
.BR t_rcvudata (3NSL),
.BR t_snddis (3NSL),
.BR attributes (7)