/*
 * ng_UI.c
 */

/*-
 * Copyright (c) 1996-1999 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Author: Julian Elischer <julian@freebsd.org>
 * $Whistle: ng_UI.c,v 1.14 1999/11/01 09:24:51 julian Exp $
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_UI.h>

/*
 * DEFINITIONS
 */

/* Everything, starting with sdlc on has defined UI as 0x03 */
#define HDLC_UI 0x03

/* Node private data */
struct ng_UI_private {
        hook_p  downlink;
        hook_p  uplink;
};
typedef struct ng_UI_private *priv_p;

/* Netgraph node methods */
static ng_constructor_t ng_UI_constructor;
static ng_rcvmsg_t      ng_UI_rcvmsg;
static ng_shutdown_t    ng_UI_shutdown;
static ng_newhook_t     ng_UI_newhook;
static ng_rcvdata_t     ng_UI_rcvdata;
static ng_disconnect_t  ng_UI_disconnect;

/* Node type descriptor */
static struct ng_type typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_UI_NODE_TYPE,
        .constructor =  ng_UI_constructor,
        .rcvmsg =       ng_UI_rcvmsg,
        .shutdown =     ng_UI_shutdown,
        .newhook =      ng_UI_newhook,
        .rcvdata =      ng_UI_rcvdata,
        .disconnect =   ng_UI_disconnect,
};
NETGRAPH_INIT(UI, &typestruct);

/************************************************************************
                        NETGRAPH NODE STUFF
 ************************************************************************/

/*
 * Create a newborn node. We start with an implicit reference.
 */

static int
ng_UI_constructor(node_p node)
{
        priv_p  priv;

        /* Allocate private structure */
        priv = malloc(sizeof(*priv), M_NETGRAPH, M_WAITOK | M_ZERO);
        NG_NODE_SET_PRIVATE(node, priv);
        return (0);
}

/*
 * Give our ok for a hook to be added
 */
static int
ng_UI_newhook(node_p node, hook_p hook, const char *name)
{
        const priv_p priv = NG_NODE_PRIVATE(node);

        if (!strcmp(name, NG_UI_HOOK_DOWNSTREAM)) {
                if (priv->downlink)
                        return (EISCONN);
                priv->downlink = hook;
        } else if (!strcmp(name, NG_UI_HOOK_UPSTREAM)) {
                if (priv->uplink)
                        return (EISCONN);
                priv->uplink = hook;
        } else
                return (EINVAL);
        return (0);
}

/*
 * Receive a control message
 */
static int
ng_UI_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        int     error;
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ng_mesg *msg;

        msg = NGI_MSG(item); /* only peeking */
        if ((msg->header.typecookie == NGM_FLOW_COOKIE) && lasthook)  {
                if (lasthook == priv->downlink) {
                        if (priv->uplink) {
                                NG_FWD_ITEM_HOOK(error, item, priv->uplink);
                                return (error);
                        }
                } else {
                        if (priv->downlink) {
                                NG_FWD_ITEM_HOOK(error, item, priv->downlink);
                                return (error);
                        }
                }
        }
                
        NG_FREE_ITEM(item);
        return (EINVAL);
}

#define MAX_ENCAPS_HDR  1
#define ERROUT(x)       do { error = (x); goto done; } while (0)

/*
 * Receive a data frame
 */
static int
ng_UI_rcvdata(hook_p hook, item_p item)
{
        const node_p node = NG_HOOK_NODE(hook);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct mbuf *m;
        int error = 0;

        NGI_GET_M(item, m);
        if (hook == priv->downlink) {
                u_char *start, *ptr;

                if (m->m_len < MAX_ENCAPS_HDR
                    && !(m = m_pullup(m, MAX_ENCAPS_HDR)))
                        ERROUT(ENOBUFS);
                ptr = start = mtod(m, u_char *);

                /* Must be UI frame */
                if (*ptr++ != HDLC_UI)
                        ERROUT(0);

                m_adj(m, ptr - start);
                NG_FWD_NEW_DATA(error, item, priv->uplink, m);  /* m -> NULL */
        } else if (hook == priv->uplink) {
                M_PREPEND(m, 1, M_NOWAIT);      /* Prepend IP NLPID */
                if (!m)
                        ERROUT(ENOBUFS);
                mtod(m, u_char *)[0] = HDLC_UI;
                NG_FWD_NEW_DATA(error, item, priv->downlink, m);        /* m -> NULL */
        } else
                panic("%s", __func__);

done:
        NG_FREE_M(m);   /* does nothing if m == NULL */
        if (item)
                NG_FREE_ITEM(item);
        return (error);
}

/*
 * Shutdown node
 */
static int
ng_UI_shutdown(node_p node)
{
        const priv_p priv = NG_NODE_PRIVATE(node);

        /* Take down netgraph node */
        free(priv, M_NETGRAPH);
        NG_NODE_SET_PRIVATE(node, NULL);
        NG_NODE_UNREF(node);
        return (0);
}

/*
 * Hook disconnection
 */
static int
ng_UI_disconnect(hook_p hook)
{
        const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

        if (hook == priv->downlink)
                priv->downlink = NULL;
        else if (hook == priv->uplink)
                priv->uplink = NULL;
        else
                panic("%s", __func__);
        /*
         * If we are not already shutting down,
         * and we have no more hooks, then DO shut down.
         */
        if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
        && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
                        ng_rmnode_self(NG_HOOK_NODE(hook));
        }
        return (0);
}