T_RCVUDERR(3NSL) Networking Services Library Functions T_RCVUDERR(3NSL)


t_rcvuderr - receive a unit data error indication


#include <xti.h>

int t_rcvuderr(int fd, struct t_uderr *uderr);


This routine is part of the XTI interfaces which evolved from the TLI
interfaces. XTI represents the future evolution of these interfaces.
However, TLI interfaces are supported for compatibility. When using a TLI
routine that has the same name as an XTI routine, the tiuser.h header
file must be used. Refer to the TLI COMPATIBILITY section for a
description of differences between the two interfaces.

This function is used in connectionless-mode to receive information
concerning an error on a previously sent data unit, and should only be
issued following a unit data error indication. It informs the transport
user that a data unit with a specific destination address and protocol
options produced an error. The argument fd identifies the local transport
endpoint through which the error report will be received, and uderr
points to a t_uderr structure containing the following members:

struct netbuf addr;
struct netbuf opt;
t_scalar_t error;

The maxlen field of addr and opt must be set before calling this function
to indicate the maximum size of the buffer for each. If this field is set
to zero for addr or opt, no information is returned in the buf field
of this parameter.

On return from this call, the addr structure specifies the destination
protocol address of the erroneous data unit, the opt structure identifies
options that were associated with the data unit, and error specifies a
protocol-dependent error code.

If the user does not care to identify the data unit that produced an
error, uderr may be set to a null pointer, and t_rcvuderr() will simply
clear the error indication without reporting any information to the user.


Upon successful completion, a value of 0 is returned. Otherwise, a
value of -1 is returned and t_errno is set to indicate an error.




On failure, t_errno is set to one of the following:

The specified file descriptor does not refer to a
transport endpoint.

The number of bytes allocated for the incoming protocol
address or options (maxlen) is greater than 0 but not
sufficient to store the information. The unit data error
information to be returned in uderr will be discarded.

This function is not supported by the underlying transport

No unit data error indication currently exists on the
specified transport endpoint.

The communications endpoint referenced by fd is not in one
of the states in which a call to this function is valid.

This error indicates that a communication problem has been
detected between XTI and the transport provider for which
there is no other suitable XTI error (t_errno).

A system error has occurred during execution of this


The XTI and TLI interface definitions have common names but use different
header files. This, and other semantic differences between the two
interfaces are described in the subsections below.

Interface Header

The XTI interfaces use the header file, xti.h. TLI interfaces should not
use this header. They should use the header:
#include <tiuser.h>

Error Description Values

The t_errno values TPROTO and TOUTSTATE can be set by the XTI interface
but not by the TLI interface.

A t_errno value that this routine can return under different
circumstances than its XTI counterpart is TBUFOVFLW. It can be returned
even when the maxlen field of the corresponding buffer has been set to

Option Buffers

The format of the options in an opt buffer is dictated by the transport
provider. Unlike the XTI interface, the TLI interface does not fix the
buffer format.


See attributes(7) for descriptions of the following attributes:

|MT Level | Safe |


t_rcvudata(3NSL), t_sndudata(3NSL), attributes(7)

May 7, 1998 T_RCVUDERR(3NSL)