t_getinfo(3N) (Networking Support Utilities) t_getinfo(3N)
NAME
tgetinfo - get protocol-specific service information
SYNOPSIS
#include <tiuser.h>
int tgetinfo(fd, info)
int fd;
struct tinfo *info;
DESCRIPTION
This function returns the current characteristics of the underlying
transport protocol associated with file descriptor fd. The info
structure is used to return the same information returned by topen.
This function enables a transport user to access this information
during any phase of communication.
This argument points to a tinfo 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 tsnddis and trcvdis functions */
long servtype;/* service type supported by 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; 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
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t_getinfo(3N) (Networking Support Utilities) t_getinfo(3N)
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; 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
tsnddis and trcvdis 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, as described below.
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 talloc
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 value of each field may change as a result of option negotiation,
and tgetinfo enables a user to retrieve the current characteristics.
The servtype field of info may specify one of the following values on
return:
TCOTS The transport provider supports a connection-mode
service but does not support the optional orderly
release facility.
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t_getinfo(3N) (Networking Support Utilities) t_getinfo(3N)
TCOTSORD The transport provider supports a connection-mode
service with the optional orderly release facility.
TCLTS The transport provider supports a connectionless-mode
service. For this service type, topen will return -2
for etsdu, connect, and discon.
On failure, terrno may be set to one of the following:
[TBADF] The specified file descriptor does not refer to a
transport endpoint.
[TSYSERR] A system error has occurred during execution of this
function.
SEE ALSO
topen(3N).
Programmer's Guide: Networking Interfaces.
DIAGNOSTICS
tgetinfo returns 0 on success and -1 on failure and terrno is set
to indicate the error.
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