Tribblix: manual page: t

T_SNDUDATA(3NSL) Networking Services Library Functions T_SNDUDATA(3NSL)

NAME

t_sndudata - send a data unit

SYNOPSIS

#include <xti.h>

int t_sndudata(int fd, const struct t_unitdata *unitdata);

DESCRIPTION

This routine is part of the XTI interfaces which evolved from the TLI
interfaces. XTI represents the future evolution of these interfaces.
However, TLI interfaces are supported for compatibility. When using a
TLI routine that has the same name as an XTI routine, the tiuser.h
header file must be used. Refer to the TLI COMPATIBILITY section
for a description of differences between the two interfaces.

This function is used in connectionless-mode to send a data unit to
another transport user. The argument fd identifies the local
transport endpoint through which data will be sent, and unitdata
points to a t_unitdata structure containing the following members:

struct netbuf addr;
struct netbuf opt;
struct netbuf udata;

In unitdata, addr specifies the protocol address of the destination
user, opt identifies options that the user wants associated with this
request, and udata specifies the user data to be sent. The user may
choose not to specify what protocol options are associated with the
transfer by setting the len field of opt to zero. In this case, the
provider uses the option values currently set for the communications
endpoint.

If the len field of udata is zero, and sending of zero octets is not
supported by the underlying transport service, the t_sndudata() will
return -1 with t_errno set to TBADDATA.

By default, t_sndudata() operates in synchronous mode and may wait if
flow control restrictions prevent the data from being accepted by the
local transport provider at the time the call is made. However, if
O_NONBLOCK is set by means of t_open(3NSL) or fcntl(2), t_sndudata()
will execute in asynchronous mode and will fail under such
conditions. The process can arrange to be notified of the clearance
of a flow control restriction by means of either t_look(3NSL) or the
EM interface.

If the amount of data specified in udata exceeds the TSDU size as
returned in the tsdu field of the info argument of t_open(3NSL) or
t_getinfo(3NSL), a TBADDATA error will be generated. If t_sndudata()
is called before the destination user has activated its transport
endpoint (see t_bind(3NSL)), the data unit may be discarded.

If it is not possible for the transport provider to immediately
detect the conditions that cause the errors TBADADDR and TBADOPT,
these errors will alternatively be returned by t_rcvuderr. Therefore,
an application must be prepared to receive these errors in both of
these ways.

If the call is interrupted, t_sndudata() will return EINTR and the
datagram will not be sent.

RETURN VALUES

Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned and t_errno is set to indicate an error.

VALID STATES

T_IDLE.

ERRORS

On failure, t_errno is set to one of the following:

TBADADDR
The specified protocol address was in an incorrect
format or contained illegal information.

TBADDATA
Illegal amount of data. A single send was attempted
specifying a TSDU greater than that specified in the
info argument, or a send of a zero byte TSDU is not
supported by the provider.

TBADF
The specified file descriptor does not refer to a
transport endpoint.

TBADOPT
The specified options were in an incorrect format or
contained illegal information.

TFLOW
O_NONBLOCK was set, but the flow control mechanism
prevented the transport provider from accepting any
data at this time.

TLOOK
An asynchronous event has occurred on this transport
endpoint.

TNOTSUPPORT
This function is not supported by the underlying
transport provider.

TOUTSTATE
The communications endpoint referenced by fd is not
in one of the states in which a call to this function
is valid.

TPROTO
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
(t_errno).

TSYSERR
A system error has occurred during execution of this
function.

TLI COMPATIBILITY

The XTI and TLI 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.

Interface Header

The XTI interfaces use the header file, xti.h. TLI interfaces should
not use this header. They should use the header:
#include <tiuser.h>

Error Description Values

The t_errno values that can be set by the XTI interface and cannot be
set by the TLI interface are:
TPROTO
TBADADDR
TBADOPT
TLOOK
TOUTSTATE

Notes

Whenever this function fails with t_error set to TFLOW, O_NONBLOCK
must have been set.

Option Buffers

The format of the options in an opt buffer is dictated by the
transport provider. Unlike the XTI interface, the TLI interface does
not fix the buffer format.

ATTRIBUTES