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update this a bit.

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mrg 1997-04-13 13:48:51 +00:00
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share/man/man9/pfil.9
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@ -1,4 +1,4 @@
.\" $NetBSD: pfil.9,v 1.3 1996/12/02 01:00:50 tls Exp $
.\" $NetBSD: pfil.9,v 1.4 1997/04/13 13:48:51 mrg Exp $
.\"
.\" Copyright (c) 1996 Matthew R. Green.
.\" All rights reserved.
@ -49,17 +49,20 @@
.\"(void *, int, struct ifnet *, int, struct mbuf **)
.Sh DESCRIPTION
The
.Fn pfil
interface allows a function to be called on every incoming, outgoing or
bad packet. The hooks for these are embedded in the ip_input and ip_output
.Nm
interface allows a function to be called on every incoming or outgoing
packets. The hooks for these are embedded in the
.Fn ip_input
and
.Fn ip_output
routines. The
.Fn pfil_hook_get
function returns the first member of a particular hook, either the in, out
or bad list. The
function returns the first member of a particular hook, either the in or out
list. The
.Fn pfil_add_hook
function takes a function of the form below as it's first argument, and the
flags for which lists to add the function to. The possible values for these
flags are some combination of PFIL_IN, PFIL_OUT and PFIL_BAD. The
flags are some combination of PFIL_IN and PFIL_OUT. The
.Fn pfil_remove_hook
removes a hook from the specified lists.
.Pp
@ -78,10 +81,13 @@ and
arguments describe the network interface and the mbuf holding data for this
packet. The
.Va dir
is the direction; 0 for incoming packets and 1 for outgoing packets.
is the direction; 0 for incoming packets and 1 for outgoing packets. if the function
returns non-zero, this signals an error and no further processing of this packet is
performed. The function should set errno to indicate the nature of the error.
It is the hook's responsibiliy to free the chain if the packet is being dropped.
.Pp
The
.Fn pfil
.Nm
interface is enabled in the kernel via the
.Sy PFIL_HOOKS
option.
@ -94,6 +100,13 @@ and
.Fn pfil_remove_hook
are expected to always succeed.
.Sh HISTORY
The pfil interface first appeared in NetBSD 1.2A.
The
.Nm
interface first appeared in
.Nx 1.3
.Sh BUGS
The current
.Nm
implementation will need changes to suit a threaded kernel model.
.Sh SEE ALSO
.Xr bpf 4
.Xr bpf 4 .