t_accept() — Accept a connect request

Standards

Standards / Extensions C or C++ Dependencies
XPG4.2 both  

Format

#define _XOPEN_SOURCE_EXTENDED 1
#include <xti.h>

int t_accept(int fd, int resfd, struct t_call *call);

General description

t_accept() is issued by a transport user to accept a connect request. The parameter fd identifies the local transport endpoint where the connect 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 contains 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() that uniquely associates the response with a previously received connect 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 connect indication arrived. Before the connection can be accepted on the same endpoint (resfd==fd), the user must have responded to any previous connect indications received on that transport endpoint (using t_accept() or t_snddis() ). Otherwise, t_accept() fails and sets 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 before the t_accept() , then the transport provider will automatically bind it to the same protocol address fd is bound to. If the transport 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.

The call to t_accept() will fail with t_errno set to TLOOK if there are indications (for example, connect or disconnect) waiting to be received on the endpoint fd.

Return of user data over a connection accept is not supported under TCP, so the udata field is always meaningless.

When the user does not indicate any option (call->opt.len == 0) it is assumed that the connection is to be accepted unconditionally. The transport provider may choose options other than the defaults to ensure that the connection is accepted successfully.

Due to implementation restrictions, behavior is undefined if a different process accepts a connection pending on an endpoint than obtained it (with t_listen).

Valid states: fd: T_INCON resfd (fd!=resfd): T_IDLE

Returned value

If successful, t_accept() returns 0.

If unsuccessful, t_accept() returns -1 and sets t_errno to one of the following values:
Error Code
Description
TACCES
The user does not have permission to accept a connection 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
An invalid sequence number was specified.
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 using t_snddis (3) or accepting them on a different endpoint using t_accept (3).
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 function was called in the wrong sequence on the transport endpoint referenced by fd, or the transport endpoint referred to by resfd is not in the appropriate state.
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 (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 0.
TSYSERR
A system error has occurred during execution of this function.

Related information

Parent topic: Library functions