/*
 * ng_rfc1490.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>
 *
 * $FreeBSD: src/sys/netgraph/ng_rfc1490.c,v 1.6.2.4 2002/07/02 22:17:18 archie Exp $
 * $Whistle: ng_rfc1490.c,v 1.22 1999/11/01 09:24:52 julian Exp $
 */

/*
 * This node does RFC 1490 multiplexing.
 *
 * NOTE: RFC 1490 is updated by RFC 2427.
 */

#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/socket.h>

#include <net/if.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include "ng_rfc1490.h"

/*
 * DEFINITIONS
 */

/* Q.922 stuff -- see RFC 1490 */
#define HDLC_UI         0x03

#define NLPID_IP        0xCC
#define NLPID_PPP       0xCF
#define NLPID_SNAP      0x80
#define NLPID_Q933      0x08
#define NLPID_CLNP      0x81
#define NLPID_ESIS      0x82
#define NLPID_ISIS      0x83

/* Node private data */
struct ng_rfc1490_private {
        hook_p  downlink;
        hook_p  ppp;
        hook_p  inet;
};
typedef struct ng_rfc1490_private *priv_p;

/* Netgraph node methods */
static ng_constructor_t ng_rfc1490_constructor;
static ng_rcvmsg_t      ng_rfc1490_rcvmsg;
static ng_shutdown_t    ng_rfc1490_rmnode;
static ng_newhook_t     ng_rfc1490_newhook;
static ng_rcvdata_t     ng_rfc1490_rcvdata;
static ng_disconnect_t  ng_rfc1490_disconnect;

/* Node type descriptor */
static struct ng_type typestruct = {
        NG_VERSION,
        NG_RFC1490_NODE_TYPE,
        NULL,
        ng_rfc1490_constructor,
        ng_rfc1490_rcvmsg,
        ng_rfc1490_rmnode,
        ng_rfc1490_newhook,
        NULL,
        NULL,
        ng_rfc1490_rcvdata,
        ng_rfc1490_rcvdata,
        ng_rfc1490_disconnect,
        NULL
};
NETGRAPH_INIT(rfc1490, &typestruct);

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

/*
 * Node constructor
 */
static int
ng_rfc1490_constructor(node_p *nodep)
{
        priv_p priv;
        int error;

        /* Allocate private structure */
        priv = kmalloc(sizeof(*priv), M_NETGRAPH, M_NOWAIT | M_ZERO);
        if (priv == NULL)
                return (ENOMEM);

        /* Call generic node constructor */
        if ((error = ng_make_node_common(&typestruct, nodep))) {
                kfree(priv, M_NETGRAPH);
                return (error);
        }
        (*nodep)->private = priv;

        /* Done */
        return (0);
}

/*
 * Give our ok for a hook to be added
 */
static int
ng_rfc1490_newhook(node_p node, hook_p hook, const char *name)
{
        const priv_p priv = node->private;

        if (!strcmp(name, NG_RFC1490_HOOK_DOWNSTREAM)) {
                if (priv->downlink)
                        return (EISCONN);
                priv->downlink = hook;
        } else if (!strcmp(name, NG_RFC1490_HOOK_PPP)) {
                if (priv->ppp)
                        return (EISCONN);
                priv->ppp = hook;
        } else if (!strcmp(name, NG_RFC1490_HOOK_INET)) {
                if (priv->inet)
                        return (EISCONN);
                priv->inet = hook;
        } else
                return (EINVAL);
        return (0);
}

/*
 * Receive a control message. We don't support any special ones.
 */
static int
ng_rfc1490_rcvmsg(node_p node, struct ng_mesg *msg,
                  const char *raddr, struct ng_mesg **rp)
{
        kfree(msg, M_NETGRAPH);
        return (EINVAL);
}

/*
 * Receive data on a hook and encapsulate according to RFC 1490.
 * Only those nodes marked (*) are supported by this routine so far.
 *
 *                            Q.922 control
 *                                 |
 *                                 |
 *            --------------------------------------------
 *            | 0x03                                     |
 *           UI                                       I Frame
 *            |                                          |
 *      ---------------------------------         --------------
 *      | 0x08  | 0x81  |0xCC   |0xCF   | 0x00    |..01....    |..10....
 *      |       |       |       |       | 0x80    |            |
 *     Q.933   CLNP    IP(*)   PPP(*)  SNAP     ISO 8208    ISO 8208
 *      |                    (rfc1973)  |       Modulo 8    Modulo 128
 *      |                               |
 *      --------------------           OUI
 *      |                  |            |
 *     L2 ID              L3 ID      -------------------------
 *      |               User         |00-80-C2               |00-00-00
 *      |               specified    |                       |
 *      |               0x70        PID                     Ethertype
 *      |                            |                       |
 *      -------------------        --------------...        ----------
 *      |0x51 |0x4E |     |0x4C    |0x1   |0xB  |           |0x806   |
 *      |     |     |     |        |      |     |           |        |
 *     7776  Q.922 Others 802.2   802.3  802.6 Others       ARP(*)  Others
 *
 *
 */

#define MAX_ENCAPS_HDR  8
#define ERROUT(x)       do { error = (x); goto done; } while (0)
#define OUICMP(P,A,B,C) ((P)[0]==(A) && (P)[1]==(B) && (P)[2]==(C))

static int
ng_rfc1490_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
{
        const node_p node = hook->node;
        const priv_p priv = node->private;
        int error = 0;

        if (hook == priv->downlink) {
                const u_char *start;
                const u_char *ptr;

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

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

                /* Eat optional zero pad byte */
                if (*ptr == 0x00)
                        ptr++;

                /* Multiplex on NLPID */
                switch (*ptr++) {
                case NLPID_SNAP:
                        if (OUICMP(ptr, 0, 0, 0)) {     /* It's an ethertype */
                                u_int16_t etype;

                                ptr += 3;
                                etype = ntohs(*((const u_int16_t *)ptr));
                                ptr += 2;
                                m_adj(m, ptr - start);
                                switch (etype) {
                                case ETHERTYPE_IP:
                                        NG_SEND_DATA(error,
                                            priv->inet, m, meta);
                                        break;
                                case ETHERTYPE_ARP:
                                case ETHERTYPE_REVARP:
                                default:
                                        ERROUT(0);
                                }
                        } else if (OUICMP(ptr, 0x00, 0x80, 0xc2))       /* 802.1 bridging */
                                ERROUT(0);
                        else    /* Other weird stuff... */
                                ERROUT(0);
                        break;
                case NLPID_IP:
                        m_adj(m, ptr - start);
                        NG_SEND_DATA(error, priv->inet, m, meta);
                        break;
                case NLPID_PPP:
                        m_adj(m, ptr - start);
                        NG_SEND_DATA(error, priv->ppp, m, meta);
                        break;
                case NLPID_Q933:
                case NLPID_CLNP:
                case NLPID_ESIS:
                case NLPID_ISIS:
                        ERROUT(0);
                default:        /* Try PPP (see RFC 1973) */
                        ptr--;  /* NLPID becomes PPP proto */
                        if ((*ptr & 0x01) == 0x01)
                                ERROUT(0);
                        m_adj(m, ptr - start);
                        NG_SEND_DATA(error, priv->ppp, m, meta);
                        break;
                }
        } else if (hook == priv->ppp) {
                M_PREPEND(m, 2, M_NOWAIT);      /* Prepend PPP NLPID */
                if (!m)
                        ERROUT(ENOBUFS);
                mtod(m, u_char *)[0] = HDLC_UI;
                mtod(m, u_char *)[1] = NLPID_PPP;
                NG_SEND_DATA(error, priv->downlink, m, meta);
        } else if (hook == priv->inet) {
                M_PREPEND(m, 2, M_NOWAIT);      /* Prepend IP NLPID */
                if (!m)
                        ERROUT(ENOBUFS);
                mtod(m, u_char *)[0] = HDLC_UI;
                mtod(m, u_char *)[1] = NLPID_IP;
                NG_SEND_DATA(error, priv->downlink, m, meta);
        } else
                panic(__func__);

done:
        NG_FREE_DATA(m, meta);
        return (error);
}

/*
 * Nuke node
 */
static int
ng_rfc1490_rmnode(node_p node)
{
        const priv_p priv = node->private;

        /* Take down netgraph node */
        node->flags |= NG_INVALID;
        ng_cutlinks(node);
        ng_unname(node);
        bzero(priv, sizeof(*priv));
        node->private = NULL;
        kfree(priv, M_NETGRAPH);
        ng_unref(node);         /* let the node escape */
        return (0);
}

/*
 * Hook disconnection
 */
static int
ng_rfc1490_disconnect(hook_p hook)
{
        const priv_p priv = hook->node->private;

        if (hook->node->numhooks == 0)
                ng_rmnode(hook->node);
        else if (hook == priv->downlink)
                priv->downlink = NULL;
        else if (hook == priv->inet)
                priv->inet = NULL;
        else if (hook == priv->ppp)
                priv->ppp = NULL;
        else
                panic(__func__);
        return (0);
}