t_open() — Establish a transport endpoint

Standards

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

Format

#define _XOPEN_SOURCE_EXTENDED 1
#include <xti.h>

int t_open(char *name, int oflag, struct t_info *info);

General description

t_open() must be called as the first step in the initialization of a transport endpoint. This function establishes a transport endpoint by supplying a transport provider identifier that indicates a particular transport provider (that is, transport protocol) and returning a file descriptor that identifies that endpoint.
Note: There must be at least one available file descriptor less than 65536.

The argument name points to a transport provider identifier. The only supported transport provider is "/dev/tcp", indicating a TCP transport provider. No device by that name actually exists in the file system. It is purely used to follow historical convention. The argument oflag identifies any open flags (as in open() ). It is constructed from O_RDWR optionally bitwise inclusive-OR'ed with O_NONBLOCK. These flags are defined by the header <fcntl.h>. The file descriptor returned by t_open() will be used by all subsequent functions to identify the particular local transport endpoint.

This function also returns various default characteristics of the underlying transport protocol by setting fields in the info structure. This argument points to a t_info structure which contains the following members: 
long addr;      /* max size of the transport protocol address  */
long options;   /* max number of bytes of                      */
                /* protocol-specific options                   */
long tsdu;      /* max size of a transport service data        */
                /* unit (TSDU)                                 */
long etsdu;     /* max size of an expedited transport          */
                /* service data unit (ETSDU)                   */
long connect;   /* max amount of data allowed on               */
                /* connection establishment functions          */
long discon;    /* max amount of data allowed on               */
                /* t_snddis() and t_rcvdis() functions         */
long servtype;  /* service type supported by the               */
                /* transport provider                          */
long flags;     /* other info about the transport provider     */
The fields take on the following values:
addr
The size of a struct sockaddr_in is returned.
options
The value 304, which is the maximum number of bytes of options which can possibly be specified or requested, is returned.
tsdu
Zero is returned, indicating that the TCP transport provider does not support the concept of TSDUs.
etsdu
A value of -1 is returned, indicating that there is no limit on the size of an ETSDU.
connect
A value of -2 is returned, indicating that the TCP transport provider does not allow data to be sent with connection establishment functions.
discon
A value of -2 is returned, indicating that the transport provider does not allow data to be sent with the abortive release functions.
servtype
T_COTS is always returned, since this is the only service type supported.
flags
The T_SENDZERO bit is always set in this field, indicating that the TCP transport provider supports the sending of zero-length TSDUs.

If info is set to a NULL pointer by the transport user, no protocol information is returned by t_open().

Valid states: T_UNINIT

Returned value

If successful, t_open() returns a valid file descriptor.

If unsuccessful, t_open() returns -1 and sets errno to one of the following values:
Error Code
Description
TBADFLAG
An invalid flag is specified.
TBADNAME
Invalid transport provider name.
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).
TSYSERR
A system error has occurred during execution of this function.

Related information

Parent topic: Library functions