t_open(3) t_open(3)
NAME [Toc] [Back]
t_open() - establish a transport endpoint
SYNOPSIS [Toc] [Back]
#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 [Toc] [Back]
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 should be /dev/tcp. For UDP,
name should be /dev/udp. (See also the OBSOLESCENT INTERFACES
section.) 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:
t_scalar_t addr; /* max size of the transport protocol */
/* address */
t_scalar_t options; /* max number of bytes of */
/* protocol-specific options */
t_scalar_t tsdu; /* max size of a transport service data */
/* unit (TSDU) */
t_scalar_t etsdu; /* max size of an expedited transport */
/* service data unit (ETSDU) */
t_scalar_t connect; /* max amount of data allowed on */
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/* connection establishment functions */
t_scalar_t discon; /* max amount of data allowed on */
/* t_snddis and t_rcvdis functions */
t_scalar_t servtype; /* service type supported by the */
/* transport provider */
t_scalar_t 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.
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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:
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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().
Thread-Safeness [Toc] [Back]
The t_open() function is safe to be called by multithreaded
applications, and it is thread-safe for both POSIX Threads and DCE
User Threads. It has a cancellation point. It is neither asynccancel
safe nor async-signal safe. Finally, it is not fork-safe.
Obsolescent Interfaces [Toc] [Back]
When using TCP and UDP through HP XTI, name can be /dev/inet_cots and
/dev/inet_clts, respectively. These names are supported for
backward-compatibility purposes. They might not be supported in
future releases, and they should be replaced with /dev/tcp and
/dev/udp, respectively.
RETURN VALUE [Toc] [Back]
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 [Toc] [Back]
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).
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SEE ALSO [Toc] [Back]
open(2), t_sync(3).
STANDARDS CONFORMANCE [Toc] [Back]
t_open(): SVID2, XPG3, XPG4
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