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 Copyright (C) 2012, Joyent, Inc. All Rights Reserved.
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 NET_HOOK_REGISTER 9F "Mar 5, 2012"
 NAME
net_hook_register - add a hook to be called in event processing

 SYNOPSIS
#include <sys/neti.h>

int net_hook_register(net_handle_t info, char *event, hook_t *hook);




 INTERFACE LEVEL
illumos DDI specific (illumos DDI).

 PARAMETERS
info


value returned from a successful call to net_protocol_register().



name


unique name for this hook.



hook


pointer to a hook_t structure.




 DESCRIPTION
The net_hook_register() function uses hooks that allow callbacks to be
registered with events that belong to a network protocol. A successful call to
net_hook_register() requires that a valid handle for a network protocol be
provided (the info parameter), along with a unique name and a hook
description that includes a reference to an available event. No two hooks on the
same netstack may share a name.


While it is possible to use the same hook_t structure with multiple calls
to net_hook_register(), it is not encouraged.


The hook_t structure passed in with this function is described by
hook_t(9S). The following describes how this structure is used.
h_func


Must be non-NULL and represent a function that fits the specified interface.



h_name


Gives the hook a name that represents its owner. No duplication of h_name
among the hooks present for an event is allowed.



h_flags


Currently unused and must be set to 0.



h_hint, h_hintvalue


Specify a hint to net_hook_register() on how to insert this hook. If the
hint cannot be specified, then an error is returned.



h_arg;


May take any value that the consumer wishes to have passed back when the hook
is activated.




 RETURN VALUES
If the net_hook_register() function succeeds, 0 is returned. Otherwise,
one of the following errors is returned:
ENOMEM


The system cannot allocate any more memory to support registering this hook.



ENXIO


A hook cannot be found among the given family of events.



EEXIST


A hook with the given h_name already exists on that event.



ESRCH


A before or after dependency cannot be satisfied due to the hook with



EBUSY


The h_hint field specifies a hint that cannot currently be satisfied
because it conflicts with another hook. An example of this might be specifying
HH_FIRST or HH_LAST when another hook has already been registered
with this value.



ESHUTDOWN


The netstack corresponding to info is condemned or no longer exists.


 CONTEXT
The net_hook_register() function may be called from user or kernel
context.

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






ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Committed



 SEE ALSO
 net_hook_unregister (9F),  hook_t (9S)