t_listen(3)

NAME

t_listen() — listen for a connect request

SYNOPSIS

#include <xti.h>            /* for X/OPEN Transport Interface - XTI */
/* or */
#include <tiuser.h>         /* for Transport Layer Interface - TLI  */

int t_listen (fd, call);
int fd;
struct t_call *call;

DESCRIPTION

The t_listen() function listens for a connect request from a calling transport user. fd identifies the local transport endpoint where connect indications arrive. On return, call contains information describing the connect indication. 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; 

The type netbuf structure is defined in the <xti.h> or <tiuser.h> header file. This structure, which is used to define buffer parameters, has the following members:

unsigned int maxlen: maximum byte length of the data buffer
unsigned int len: actual byte length of data written to buffer
char *buf: points to buffer location

In call, addr returns the protocol address of the calling transport user. This address is in a format usable in future calls to t_connect(). Note, however that t_connect() may fail for other reasons, for example [TADDRBUSY].

opt returns protocol-specific parameters associated with the connect request. For XTI over the OSI transport provider, struct isoco_options should be used. For TLI, see the documentation for the transport provider being used.

udata returns any user data sent by the caller on the connect request.

sequence is a number that uniquely identifies the returned connect indication. The value of sequence enables the user to listen for multiple connect indications before responding to any of them.

Since this function returns values for the addr, opt, and udata fields of call, the maxlen field of each must be set before issuing the t_listen to indicate the maximum size of the buffer for each.

By default, t_listen executes in synchronous mode and waits for a connect indication to arrive before returning to the user. However, if O_NONBLOCK is set (via t_open() or fcntl()), t_listen() executes asynchronously, reducing to a poll for existing connect indications. If none are available, it returns -1 and sets t_errno to [TNODATA].

Valid States

T_IDLE, T_INCON

Caveats

Some transport providers do not differentiate between a connect indication and the connection itself. If this is the case, a successful return of t_listen() indicates an existing connection (see Appendix B, "Internet Protocol-specific Information," of the CAE Specification X/Open Transport Interface (XTI) manual).

Fork Safety

t_listen is not fork-safe.

RETURN VALUE

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

ERRORS

On failure, t_errno is set to the following:

[TBADF]: The specified identifier does not refer to a transport endpoint.
[TBADQLEN]: The argument qlen of the endpoint referenced by fd is zero.
[TBUFOVFLW]: The number of bytes allocated for an incoming argument ( maxlen) is not sufficient to store the value of that argument. The provider's state, as seen by the user, changes to T_INCON, and the connect indication information to be returned in call is discarded. For XTI only, the value of sequence returned can be used to do a t_snddis().
[TNODATA]: O_NONBLOCK was set, but no connect indication has been queued.
[TLOOK]: An asynchronous event has occurred on this transport endpoint and requires immediate attention.
[TOUTSTATE]: This function was issued in the wrong sequence on the transport endpoint referenced by fd.
[TSYSERR]: A system error has occurred during execution of this function.
[TQFULL]: The maximum number of outstanding indications has been reached for the endpoint referenced by fd.
[TPROTO]: (XTI only) This error indicates that a communication problem has been detected between XTI and the transport provider for which there is no suitable XTI (t_errno).

FILES

/usr/include/xti.h: XTI data structures
/usr/include/tiuser.h: TLI data structures

STANDARDS CONFORMANCE

t_listen(): SVID2, XPG3, XPG4