T_ACCEPT(3NSL)T_ACCEPT(3NSL)NAMEt_accept - accept a connection request
SYNOPSIS
#include <xti.h>
int t_accept(int fd, int resfd, const struct t_call *call);
DESCRIPTION
This routine is part of the XTI interfaces that 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, a different
header file, tiuser.h, must be used. Refer to the TLI COMPATIBILITY
section for a description of differences between the two interfaces.
This function is issued by a transport user to accept a connection
request. The parameter fd identifies the local transport endpoint
where the connection indication arrived; resfd specifies the local
transport endpoint where the connection is to be established, and call
contains information required by the transport provider to complete the
connection. The parameter call points to a t_call structure which con‐
tains the following members:
struct netbuf addr;
struct netbuf opt;
struct netbuf udata;
int sequence;
In call, addr is the protocol address of the calling transport user,
opt indicates any options associated with the connection, udata points
to any user data to be returned to the caller, and sequence is the
value returned by t_listen(3NSL) that uniquely associates the response
with a previously received connection indication. The address of the
caller, addr may be null (length zero). Where addr is not null then it
may optionally be checked by XTI.
A transport user may accept a connection on either the same, or on a
different, local transport endpoint than the one on which the connec‐
tion indication arrived. Before the connection can be accepted on the
same endpoint (resfd==fd), the user must have responded to any previous
connection indications received on that transport endpoint by means of
t_accept() or t_snddis(3NSL). Otherwise, t_accept() will fail and set
t_errno to TINDOUT.
If a different transport endpoint is specified (resfd!=fd), then the
user may or may not choose to bind the endpoint before the t_accept()
is issued. If the endpoint is not bound prior to the t_accept(), the
endpoint must be in the T_UNBND state before the t_accept() is
issued, and the transport provider will automatically bind it to an
address that is appropriate for the protocol concerned. If the trans‐
port user chooses to bind the endpoint it must be bound to a protocol
address with a qlen of zero and must be in the T_IDLE state before the
t_accept() is issued.
Responding endpoints should be supplied to t_accept() in the state
T_UNBND.
The call to t_accept() may fail with t_errno set to TLOOK if there are
indications (for example connect or disconnect) waiting to be received
on endpoint fd. Applications should be prepared for such a failure.
The udata argument enables the called transport user to send user data
to the caller and the amount of user data must not exceed the limits
supported by the transport provider as returned in the connect field of
the info argument of t_open(3NSL) or t_getinfo(3NSL). If the len field
of udata is zero, no data will be sent to the caller. All the maxlen
fields are meaningless.
When the user does not indicate any option (call→opt.len = 0) the con‐
nection shall be accepted with the option values currently set for the
responding endpoint resfd.
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
fd: T_INCON
resfd (fd!=resfd): T_IDLE, T_UNBND
ERRORS
On failure, t_errno is set to one of the following:
TACCES
The user does not have permission to accept a connec‐
tion on the responding transport endpoint or to use
the specified options.
TBADADDR
The specified protocol address was in an incorrect
format or contained illegal information.
TBADDATA
The amount of user data specified was not within the
bounds allowed by the transport provider.
TBADF
The file descriptor fd or resfd does not refer to a
transport endpoint.
TBADOPT
The specified options were in an incorrect format or
contained illegal information.
TBADSEQ
Either an invalid sequence number was specified, or a
valid sequence number was specified but the connection
request was aborted by the peer. In the latter case,
its T_DISCONNECT event will be received on the lis‐
tening endpoint.
TINDOUT
The function was called with fd==resfd but there are
outstanding connection indications on the endpoint.
Those other connection indications must be handled
either by rejecting them by means of t_snddis(3NSL)
or accepting them on a different endpoint by means of
t_accept.
TLOOK
An asynchronous event has occurred on the transport
endpoint referenced by fd and requires immediate
attention.
TNOTSUPPORT
This function is not supported by the underlying
transport provider.
TOUTSTATE
The communications endpoint referenced by fd or
resfd 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).
TPROVMISMATCH
The file descriptors fd and resfd do not refer to the
same transport provider.
TRESADDR
This transport provider requires both fd and resfd to
be bound to the same address. This error results if
they are not.
TRESQLEN
The endpoint referenced by resfd (where resfd != fd)
was bound to a protocol address with a qlen that is
greater than zero.
TSYSERR
A system error has occurred during execution of this
function.
TLI COMPATIBILITY
The XTI and TLI interface definitions have common names but use differ‐
ent 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
TINDOUT
TPROVMISMATCH
TRESADDR
TRESQLEN
Option Buffer
The format of the options in an opt buffer is dictated by the transport
provider. Unlike the XTI interface, the TLI interface does not specify
the buffer format.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌───────────────┬─────────────────┐
│ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├───────────────┼─────────────────┤
│MT Level │ Safe │
└───────────────┴─────────────────┘
SEE ALSOt_connect(3NSL), t_getinfo(3NSL), t_getstate(3NSL), t_listen(3NSL),
t_open(3NSL), t_optmgmt(3NSL), t_rcvconnect(3NSL), t_snddis(3NSL),
attributes(5)WARNINGS
There may be transport provider-specific restrictions on address bind‐
ing.
Some transport providers do not differentiate between a connection
indication and the connection itself. If the connection has already
been established after a successful return of t_listen(3NSL),
t_accept() will assign the existing connection to the transport end‐
point specified by resfd.
May 1, 1998 T_ACCEPT(3NSL)
