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 provider.
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 function.
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.
The XTI interfaces use the header file, xti.h. TLI interfaces should not use this header. They should use the header:
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 zero.
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: