t_open(3)
NAME
t_open() − establish a transport endpoint
SYNOPSIS
#include <fcntl.h>
#include <xti.h> (for X/OPEN Transport Interface - XTI)
or
#include <tiuser.h> (for Transport Layer Interface - TLI)
int t_open (name, oflag, info)
char *name;
int oflag;
struct t_info *info;
DESCRIPTION
The t_open() function must be called as the first step in the initialization of a transport endpoint. This function establishes a transport endpoint by opening a file that identifies a particular transport provider and returning a file descriptor that identifies that endpoint.
The argument name points to a file name that identifies a transport provider. When using HP XTI to connect to the OSI protocol stack, name must be /dev/ositpi for the connection-mode service, or /dev/osicltpi for the connectionless service. When using HP XTI to connect to the TCP protocol stack, name must be /dev/inet_cots. For UDP, name must be /dev/inet_clts. For TLI, use the device file name of the transport provider desired. Note that HP TCP/UDP/IP and HP OSI COTS and CLTS only support XTI.
oflag identifies any open flags (as in open()) and is constructed from O_RDWR optionally or-ed with O_NONBLOCK. These flags are defined by the header file <fcntl.h>. t_open() returns a file descriptor that 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 t_info structure. This argument points to a t_info 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 values of the fields have the following meanings:
addr A value greater than or equal to zero indicates the maximum size of a transport protocol address.
A value of -1 specifies that there is no limit on the address size.
A value of -2 specifies that the transport provider does not provide user access to transport protocol addresses.
options A value greater than or equal to zero indicates the maximum number of bytes of protocol-specific options supported by the provider.
A value of -1 specifies that there is no limit on the option size.
A value of -2 specifies that the transport provider does not support user-settable options.
tsdu A value greater than zero specifies the maximum size of a transport service data unit (TSDU).
A value of zero specifies that the transport provider does not support the concept of TSDU, although it does support the sending of a data stream with no logical boundaries preserved across a connection.
A value of -1 specifies that there is no limit on the size of a TSDU.
A value of -2 specifies that the transfer of normal data is not supported by the transport provider.
etsdu A value greater than zero specifies the maximum size of an expedited transport service data unit (ETSDU).
A value of zero specifies that the transport provider does not support the concept of ETSDU, although it does support the sending of an expedited data stream with no logical boundaries preserved across a connection.
A value of -1 specifies that there is no limit on the size of an ETSDU.
A value of -2 specifies that the transfer of expedited data is not supported by the transport provider.
connect A value greater than or equal to zero specifies the maximum amount of data that may be associated with the connection establishment functions t_connect() and t_rcvconnect().
A value of -1 specifies that there is no limit on the amount of data sent during connection establishment.
A value of -2 specifies that the transport provider does not allow data to be sent with connection establishment functions.
discon A value greater than or equal to zero specifies the maximum amount of data that may be associated with the and functions.
A value of -1 specifies that there is no limit on the amount of data sent with these abortive release functions.
A value of -2 specifies that the transport provider does not allow data to be sent with the abortive release functions.
servtype This field specifies the service type supported by the transport provider, as described below.
flags This is a bit field used to specify other information about the transport provider. If the T_SENDZERO bit is set in flags, this indicates the underlying transport provider supports the sending of zero-length TSDUs. See Appendix A, "ISO Transport Protocol Information," of the CAE Specification X/Open Transport Interface (XTI) manual from X/Open Company Limited for a discussion of the separate issue of zero-length fragments within a TSDU.
If a transport user is concerned with protocol independence, the above sizes may be accessed to determine how large the buffer must be to hold each piece of information. Alternatively, the t_alloc() function may be used to allocate these buffers. An error will result if a transport user exceeds the allowed data size on any function.
The servtype field of info specifies one of the following values on return:
T_COTS The transport provider supports a connection-mode service but does not support the optional orderly release facility.
T_COTS_ORD The transport provider supports a connection-mode service with the optional orderly release facility.
T_CLTS The transport provider supports a connectionless-mode service. For this service type, t_open() will return -2 for etsdu, connect, and discon.
A single transport endpoint may support only one of the above services at one time.
If info is set to a null pointer by the transport user, no protocol information is returned by t_open().
RETURN VALUE
A valid endpoint identifier is returned upon successful completion. Otherwise, a value of -1 is returned and t_errno is set to indicate an error.
HP OSI does not support the T_COTS_ORD servtype.
ERRORS
On error, t_errno is set to one of the following:
[TBADFLAG] An invalid flag is specified.
[TBADNAME] Invalid transport provider name.
[TSYSERR] A system error has occurred during execution of this function.
[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).
SEE ALSO
STANDARDS CONFORMANCE
t_open(): SVID2, XPG3, XPG4
Hewlett-Packard Company — HP-UX Release 10.20: July 1996