.\"
.\" Copyright (c) 2004
.\"	Hartmut Brandt.
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.\" Author: Hartmut Brandt <harti@FreeBSD.org>
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.\" $FreeBSD$
.\"
.\" ngatmbase(4) man page
.\"
.Dd August 24, 2004
.Dt NGATMBASE 4
.Os
.Sh NAME
.Nm ngatmbase
.Nd netgraph ATM utility module
.Sh SYNOPSIS
.In netnatm/unimsg.h
.In netgraph/atm/ngatmbase.h
.Ft "struct mbuf *"
.Fn uni_msg_pack_mbuf "struct uni_msg *msg" "void *hdr" "size_t len"
.Ft "struct uni_msg *"
.Fn uni_msg_alloc "size_t len"
.Ft "struct uni_msg *"
.Fn uni_msg_build "void *buf" ...
.Ft void
.Fn uni_msg_destroy "struct uni_msg *msg"
.Ft int
.Fn uni_msg_unpack_mbuf "struct mbuf *m" "struct uni_msg *msgp"
.Sh DESCRIPTION
This module provides utility functions for the handling of signalling
messages to the NgATM modules.
.Pp
The
.Fn uni_msg_pack_mbuf
function
packs a message into one or several
.Vt mbuf Ns s
optionally prepending a header.
The header is given by its address
.Fa hdr
and length
.Fa len .
If
.Fa hdr
is
.Dv NULL
or
.Fa len
equals 0, no header is prepended.
Either
.Fa msg
or
.Fa hdr
may be
.Dv NULL
but not both.
The
.Fn uni_msg_pack_mbuf
function
returns a pointer to the allocated
.Vt mbuf
chain or
.Dv NULL
in the case of an error.
.Pp
The
.Fn uni_msg_alloc
function
allocates a new message with space for at least
.Fa len
bytes.
In the case of an error
.Dv NULL
is returned.
.Pp
The
.Fn uni_msg_build
function constructs a message from pieces.
Each piece is given by a pair of
arguments, the first of type
.Vt "void *"
and the second a
.Vt size_t .
The list of pieces must be terminated by
.Po Vt "void *" Pc Ns Dv NULL .
.Pp
The
.Fn uni_msg_destroy
function
destroys the messages and frees all the messages's memory.
.Pp
The
.Fn uni_msg_unpack_mbuf
function
unpacks an
.Vt mbuf
chain info a
.Vt uni_msg .
A pointer to the newly allocated message is stored in
.Fa msgp
and 0 is returned.
In the case of an error (either when no packet header is found
in the first mbuf or memory cannot be allocated) the function
returns an appropriate error code.
.Sh SEE ALSO
.Xr ng_ccatm 4 ,
.Xr ng_sscfu 4 ,
.Xr ng_sscop 4 ,
.Xr ng_uni 4
.Sh AUTHORS
.An Harti Brandt Aq Mt harti@FreeBSD.org