HP X.25/9000 Programmer's Guide

Chapter 5 85
Receiving and Transmitting Out-of-band Information
Transmitting Out-of-band Events
The X.25 subsystem sends a RESET CONFIRMATION packet when the
application reads the RESET out-of-band event without the MSG_PEEK
flag set.
If nonblocking I/O is in effect, the ioctl(X25_RESET_VC) call does not
block the caller. If a RESET CONFIRMATION packet arrives and the
socket is in the nonblocking state, an out-of-band event
(OOB_RESET_CONF) is placed in the socket’s out-of-band queue. Also,
SIGURG is sent to the process, which must have a signal handler
installed for the SIGURG signal and enabled the socket to transmit
SIGURG signals.
Syntax for ioctl(X25_RESET_VC)
The ioctl(X25_RESET_VC) and its parameters are described below.
int err;
int sd;
err = ioctl(sd, X25_RESET_VC, 0);
sd Socket descriptor for an VC socket.
X25_RESET_VC Definition for the request which cause a RESET packet to be sent on the
VC.
0 Dummy parameter for the system call.
err On successful completion, err is set to 0. Otherwise, a value of –1 is
returned and errno is set to indicate the error.
CAUTION All X.25 applications should be designed to handle out-of-band
information. Failure to do so can cause SVCs to be cleared and PVCs to
become unusable until your application process is terminated.
Sending Interrupts on a VC
An INTERRUPT packet can be sent at any time by either side of a VC
after call connection has been established.
X.25 supports sending up to 32 bytes of interrupt data in an
INTERRUPT packet.
36960-90061.bk Page 85 Friday, November 10, 2000 3:42 PM