'\" te
.\" Copyright (C) 2008, Sun Microsystems, Inc. All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH NET_EVENT_NOTIFY_REGISTER 9F "Oct 30, 2008"
.SH NAME
net_event_notify_register, net_event_notify_unregister \- add/delete a function
to be called for changes to a event
.SH SYNOPSIS
.nf
#include <sys/hook.h>
#include <sys/neti.h>

\fBint\fR \fBnet_event_notify_register\fR(\fBnet_handle_t\fR \fIfamily\fR, \fBchar\fR
     *\fIevent\fR, \fBhook_notify_fn_t\fR *\fIcallback\fR, \fBvoid\fR *\fIarg\fR);

\fBint\fR \fBnet_event_notify_unregister\fR(\fBnet_handle_t\fR \fIfamily\fR, \fBchar\fR
     *\fIevent\fR, \fBhook_notify_fn_t\fR *\fIcallback\fR);

\fBtypedef int\fR (* \fBhook_notify_fn_t\fR)(\fBhook_notify_cmd_t command,\fR
     \fBvoid\fR *\fIarg\fR, \fBconst char\fR *\fIname1\fR, \fBconst char\fR *\fIname2\fR, \fBconst char\fR
     *\fIname3\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI).
.SH PARAMETERS
.ne 2
.na
\fB\fIfamily\fR\fR
.ad
.RS 12n
value returned from a successful call to \fBnet_protocol_lookup()\fR.
.RE

.sp
.ne 2
.na
\fB\fIcallback\fR\fR
.ad
.RS 12n
function to call when a change occurs.
.RE

.sp
.ne 2
.na
\fB\fIevent\fR\fR
.ad
.RS 12n
name of the event for which notification of change is desired.
.RE

.sp
.ne 2
.na
\fB\fIarg\fR\fR
.ad
.RS 12n
pointer to pass into the \fBcallback()\fR function when a change occurs.
.RE

.SH DESCRIPTION
The \fBnet_event_notify_register()\fR function registers a function represented
by the pointer \fIcallback\fR to be called when there is a change to the event
represented by \fIfamily\fR. The types of changes for which notifications are
available for is currently limited to the addition and removal of hooks.
.sp
.LP
The \fBnet_event_notify_unregister()\fR function indicates that there is no
longer any desire to receive notification of changes to the event through
function calls to the specified \fIcallback\fR.
.sp
.LP
The name of a hook should be considered a private interface unless otherwise
specified. The hook names used by \fBIPFilter\fR in illumos are a public, but
uncommitted, interface.
.sp
.LP
Multiple \fIcallback\fR functions may be registered through this interface. The
same set of parameters is passed to each \fIcallback\fR function. The memory
referenced through the pointers passed to  the  \fIcallback\fR should be
treated as pointing to read-only memory. Changing this data is strictly
prohibited.
.sp
.LP
The function that is called when the \fIevent\fR occurs must not block any
other events.
.sp
.LP
The arguments passed through to the \fBcallback\fR are as follows (the command
is either \fBHN_REGISTER\fR or \fBHN_UNREGISTER\fR):
.sp
.ne 2
.na
\fB\fIname1\fR\fR
.ad
.RS 9n
is the name of the protocol.
.RE

.sp
.ne 2
.na
\fB\fIname2\fR\fR
.ad
.RS 9n
is the name of the event
.RE

.sp
.ne 2
.na
\fB\fIname3\fR\fR
.ad
.RS 9n
is the name of the hook being added/removed
.RE

.SH RETURN VALUES
If these functions succeed, 0 is returned. Otherwise, the following error is
returned:
.sp
.ne 2
.na
\fBEEXIST\fR
.ad
.RS 10n
the given callback function is already registered.
.RE

.SH CONTEXT
These functions may be called from user or kernel context.
.SH ATTRIBUTES
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
.TE

.SH SEE ALSO
.BR attributes (7),
.BR net_hook_register (9F),
.BR net_hook_unregister (9F),
.BR net_protocol_lookup (9F)