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.TH T_CONNECT 3NSL "May 7, 1998"
.SH NAME
t_connect \- establish a connection with another transport user
.SH SYNOPSIS
.LP
.nf
#include <xti.h>

\fBint\fR \fBt_connect\fR(\fBint\fR \fIfd\fR, \fBconst struct t_call *\fR\fIsndcall\fR,
     \fBstruct t_call *\fR\fIrcvcall\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. This function enables a transport user to request a connection to
the specified destination transport user.
.sp
.LP
This function can only be issued in the  \fBT_IDLE\fR state. The parameter
\fIfd\fR identifies the local transport endpoint where communication will be
established, while \fIsndcall\fR and \fIrcvcall\fR point to a \fBt_call\fR
structure which contains the following members:
.sp
.in +2
.nf
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
int sequence;
.fi
.in -2

.sp
.LP
The parameter \fIsndcall\fR specifies information needed by the transport
provider to establish a connection and \fIrcvcall\fR specifies information that
is associated with the newly established connection.
.sp
.LP
In \fIsndcall\fR, \fIaddr\fR specifies the protocol address of the destination
transport user, \fIopt\fR presents any protocol-specific information that might
be needed by the transport provider, \fIudata\fR points to optional user data
that may be passed to the destination transport user during connection
establishment, and \fIsequence\fR has no meaning for this function.
.sp
.LP
On return, in \fIrcvcall\fR, \fIaddr\fR contains the protocol address
associated with the responding transport endpoint, \fIopt\fR represents any
protocol-specific information associated with the connection, \fIudata\fR
points to optional user data that may be returned by the destination transport
user during connection establishment, and \fIsequence\fR has no meaning for
this function.
.sp
.LP
The \fIopt\fR argument permits users to define the options that may be passed
to the transport provider. The user may choose not to negotiate protocol
options by setting the \fIlen\fR field of \fIopt\fR to zero. In this case, the
provider uses the option values currently set for the communications endpoint.
.sp
.LP
If used, \fIsndcall\(->opt.buf\fR must point to a buffer with the corresponding
options, and  \fIsndcall\(->opt.len\fR must specify its length. The
\fImaxlen\fR and \fIbuf\fR fields of the \fBnetbuf\fR structure pointed by
\fIrcvcall\(->addr\fR and \fIrcvcall\(->opt\fR must be set before the call.
.sp
.LP
The \fIudata\fR argument enables the caller to pass user data to the
destination transport user and receive user data from the destination user
during connection establishment. However, the amount of user data must not
exceed the limits supported by the transport provider as returned in the
\fIconnect\fR field of the \fIinfo\fR argument of \fBt_open\fR(3NSL) or
\fBt_getinfo\fR(3NSL). If the \fIlen\fR of \fIudata\fR is zero in
\fIsndcall\fR, no data will be sent to the destination transport user.
.sp
.LP
On return, the \fIaddr\fR, \fIopt\fR and \fIudata\fR fields of \fIrcvcall\fR
will be updated to reflect values associated with the connection. Thus, the
\fImaxlen\fR field of each argument must be set before issuing this function to
indicate the maximum size of the buffer for each. However, \fImaxlen\fR can be
set to zero, in which case no information to this specific argument is given to
the user on the return from  \fBt_connect()\fR. If maxlen is greater than zero
and less than the length of the value,  \fBt_connect()\fR fails with
\fBt_errno\fR set to \fBTBUFOVFLW\fR. If  \fIrcvcall\fR is set to  \fINULL,\fR
no information at all is returned.
.sp
.LP
By default, \fBt_connect()\fR executes in synchronous mode, and will wait for
the destination user's response before returning control to the local user. A
successful return (that is, return value of zero) indicates that the requested
connection has been established. However, if  \fBO_NONBLOCK\fR is set  by means
of \fBt_open\fR(3NSL) or \fBfcntl\fR(2), \fBt_connect()\fR executes in
asynchronous mode. In this case, the call will not wait for the remote user's
response, but will return control immediately to the local user and return  -1
with \fBt_errno\fR set to \fBTNODATA\fR to indicate that the connection has not
yet been established. In this way, the function simply initiates the connection
establishment procedure by sending a connection request to the destination
transport user. The \fBt_rcvconnect\fR(3NSL) function is used in conjunction
with \fBt_connect()\fR to determine the status of the requested connection.
.sp
.LP
When a synchronous \fBt_connect()\fR call is interrupted by the arrival of a
signal, the state of the corresponding transport endpoint is  \fBT_OUTCON,\fR
allowing a further call to either \fBt_rcvconnect\fR(3NSL),
\fBt_rcvdis\fR(3NSL) or \fBt_snddis\fR(3NSL). When an asynchronous
\fBt_connect()\fR call is interrupted by the arrival of a signal,  the state of
the corresponding transport endpoint is  \fBT_IDLE.\fR
.SH RETURN VALUES
.sp
.LP
Upon successful completion, a value of  \fB0\fR is returned.  Otherwise, a
value of  -1 is returned and \fBt_errno\fR is set to indicate an error.
.SH VALID STATES
.sp
.LP
\fBT_IDLE\fR
.SH ERRORS
.sp
.LP
On failure, \fBt_errno\fR is set to one of the following:
.sp
.ne 2
.na
\fB\fBTACCES\fR\fR
.ad
.RS 15n
The user does not have permission to use the specified address or options.
.RE

.sp
.ne 2
.na
\fB\fBTADDRBUSY\fR\fR
.ad
.RS 15n
This transport provider does not support multiple connections with the same
local and remote addresses. This error indicates that a connection already
exists.
.RE

.sp
.ne 2
.na
\fB\fBTBADADDR\fR\fR
.ad
.RS 15n
The specified protocol address was in an incorrect format or contained illegal
information.
.RE

.sp
.ne 2
.na
\fB\fBTBADDATA\fR\fR
.ad
.RS 15n
The amount of user data specified was not within the bounds allowed by the
transport provider.
.RE

.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\fBTBADOPT\fR\fR
.ad
.RS 15n
The specified protocol 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 allocated for an incoming argument \fI(maxlen)\fR is
greater than 0 but not sufficient to store the value of that argument. If
executed in synchronous mode, the provider's state, as seen by the user,
changes to \fBT_DATAXFER,\fR and the information to be returned in
\fIrcvcall\fR is discarded.
.RE

.sp
.ne 2
.na
\fB\fBTLOOK\fR\fR
.ad
.RS 15n
An asynchronous event has occurred on this transport endpoint and requires
immediate attention.
.RE

.sp
.ne 2
.na
\fB\fBTNODATA\fR\fR
.ad
.RS 15n
\fBO_NONBLOCK\fR was set, so the function successfully initiated the connection
establishment procedure, but did not wait for a response from the remote user.
.RE

.sp
.ne 2
.na
\fB\fBTNOTSUPPORT\fR\fR
.ad
.RS 15n
This function is not supported by the underlying 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 \fBTPROTO\fR and \fBTADDRBUSY\fR \fBt_errno\fR values can be set by the
\fBXTI\fR interface but not by the \fBTLI\fR interface.
.sp
.LP
A \fBt_errno\fR value that this routine can return under different
circumstances than its \fBXTI\fR counterpart is \fBTBUFOVFLW\fR. It can be
returned even when the \fBmaxlen\fR field of the corresponding buffer has been
set to zero.
.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.
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5)  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
\fBfcntl\fR(2), \fBt_accept\fR(3NSL), \fBt_alloc\fR(3NSL),
\fBt_getinfo\fR(3NSL), \fBt_listen\fR(3NSL), \fBt_open\fR(3NSL),
\fBt_optmgmt\fR(3NSL), \fBt_rcvconnect\fR(3NSL), \fBt_rcvdis\fR(3NSL),
\fBt_snddis\fR(3NSL), \fBattributes\fR