Manual page for T_OPEN(3N)
t_open - establish a transport endpoint
SYNOPSIS
#include <tiuser.h>
int t_open(path, oflag, info)
char *path;
int oflag;
struct t_info *info;
DESCRIPTION
t_open()
must be called as the first step in the initialization of a
transport endpoint.
It establishes a transport endpoint by opening a
file that identifies a particular transport provider
(such as a transport protocol) and returning a file descriptor that
identifies that endpoint.
For example, opening the file
/dev/tcp
identifies an
OSI
connection-oriented transport layer protocol
as the transport provider.
Currently,
/dev/tcp
is the only transport protocol available to
t_open().
path
points to the pathname of the file to open, and
oflag
identifies any open flags (as in
open.2v
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 pointed to by
info.
t_info
is defined in
<nettli/tiuser.h>
as:
-
struct t_info {
long addr; /* size of protocol address */
long options; /* size of protocol options */
long tsdu; /* size of max transport service data unit */
long etsdu; /* size of max expedited tsdu */
long connect; /* max data for connection primitives */
long discon; /* max data for disconnect primitives */
long servtype; /* provider service type */
};
The fields of this structure have the following values:
- 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; and 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; and 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;
and a value of -2 specifies that the transfer of normal data is
not supported by the transport provider.
- etdsu
-
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;
and 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
connection establishment functions;
a value of -1 specifies that there is no limit on the amount of data
sent during connection establishment;
and 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
t_snddis.3n
and
t_rcvdis.3n
functions;
a value of -1 specifies that there is no limit on the amount of data
sent with these abortive release functions;
and 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.
The
servtype
field of
info
may specify 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
NULL
by the transport user, no protocol information is
returned by
t_open().
If a transport user is concerned with protocol independence, the above
sizes may be accessed to determine how large the buffers must be
to hold each piece of information.
Alternatively, the
t_alloc.3n
function may be used to allocate these
buffers.
An error will result if a transport user exceeds the allowed
data size on any function.
RETURN VALUES
t_open()
returns
a non-negative file descriptor
on success.
On failure,
it returns
-1
and sets
t_errno
to indicate the error.
ERRORS
- TSYSERR
-
The function failed due to a system error and set
errno
to indicate the error.
SEE ALSO
open.2v
tcp.4p
[a manual with the abbreviation NETP]
Created by unroff & hp-tools.
© somebody (See intro for details). All Rights Reserved.
Last modified 11/5/97