/*
 * 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>
 * $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/errno.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 <netgraph/ng_parse.h>
#include <netgraph/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

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

/* Encapsulation methods we understand */
enum {
	NG_RFC1490_ENCAP_IETF_IP = 1,	/* see RFC2427, chapter 7, table 1 */
	NG_RFC1490_ENCAP_IETF_SNAP,	/* see RFC2427, chapter 7, table 2 */
	NG_RFC1490_ENCAP_CISCO,		/* Cisco's proprietary encapsulation */
};

struct ng_rfc1490_encap_t {
	u_int8_t	method;
	const char	*name;
};

static const struct ng_rfc1490_encap_t ng_rfc1490_encaps[] = {
	{ NG_RFC1490_ENCAP_IETF_IP,	"ietf-ip" },
	{ NG_RFC1490_ENCAP_IETF_SNAP,	"ietf-snap" },
	{ NG_RFC1490_ENCAP_CISCO,	"cisco" },
	{ 0, NULL},
};

/* Node private data */
struct ng_rfc1490_private {
	hook_p  downlink;
	hook_p  ppp;
	hook_p  inet;
	hook_p  ethernet;
	const struct ng_rfc1490_encap_t *enc;
};
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_shutdown;
static ng_newhook_t	ng_rfc1490_newhook;
static ng_rcvdata_t	ng_rfc1490_rcvdata;
static ng_disconnect_t	ng_rfc1490_disconnect;

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_rfc1490_cmds[] = {
	{
	  NGM_RFC1490_COOKIE,
	  NGM_RFC1490_SET_ENCAP,
	  "setencap",
	  &ng_parse_string_type,
	  NULL
	},
	{
	  NGM_RFC1490_COOKIE,
	  NGM_RFC1490_GET_ENCAP,
	  "getencap",
	  NULL,
	  &ng_parse_string_type
	},
	{ 0 }
};

/* Node type descriptor */
static struct ng_type typestruct = {
	.version =	NG_ABI_VERSION,
	.name =		NG_RFC1490_NODE_TYPE,
	.constructor =	ng_rfc1490_constructor,
	.rcvmsg =	ng_rfc1490_rcvmsg,
	.shutdown =	ng_rfc1490_shutdown,
	.newhook =	ng_rfc1490_newhook,
	.rcvdata =	ng_rfc1490_rcvdata,
	.disconnect =	ng_rfc1490_disconnect,
	.cmdlist =	ng_rfc1490_cmds,
};
NETGRAPH_INIT(rfc1490, &typestruct);

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

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

	/* Allocate private structure */
	priv = malloc(sizeof(*priv), M_NETGRAPH, M_WAITOK | M_ZERO);

	/* Initialize to default encapsulation method - ietf-ip */
	priv->enc = ng_rfc1490_encaps;

	NG_NODE_SET_PRIVATE(node, 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 = NG_NODE_PRIVATE(node);

	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 if (!strcmp(name, NG_RFC1490_HOOK_ETHERNET)) {
		if (priv->ethernet)
			return (EISCONN);
		priv->ethernet = hook;
	} else
		return (EINVAL);
	return (0);
}

/*
 * Receive a control message.
 */
static int
ng_rfc1490_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
	const priv_p priv = NG_NODE_PRIVATE(node);
	struct ng_mesg *msg;
	struct ng_mesg *resp = NULL;
	int error = 0;

	NGI_GET_MSG(item, msg);

	if (msg->header.typecookie == NGM_RFC1490_COOKIE) {
		switch (msg->header.cmd) {
		case NGM_RFC1490_SET_ENCAP:
		{
			const struct ng_rfc1490_encap_t *enc;
			char *s;
			size_t len;

			if (msg->header.arglen == 0)
				ERROUT(EINVAL);

			s = (char *)msg->data;
			len = msg->header.arglen - 1;

			/* Search for matching encapsulation method */
			for (enc = ng_rfc1490_encaps; enc->method != 0; enc++ )
				if ((strlen(enc->name) == len) &&
				    !strncmp(enc->name, s, len))
					break;	/* found */

			if (enc->method != 0)
				priv->enc = enc;
			else
				error = EINVAL;
			break;
		}
		case NGM_RFC1490_GET_ENCAP:

			NG_MKRESPONSE(resp, msg, strlen(priv->enc->name) + 1, M_NOWAIT);
			if (resp == NULL)
				ERROUT(ENOMEM);

			strlcpy((char *)resp->data, priv->enc->name,
			    strlen(priv->enc->name) + 1);
			break;

		default:
			error = EINVAL;
			break;
		}
	} else
		error = EINVAL;

done:
	NG_RESPOND_MSG(error, node, item, resp);
	NG_FREE_MSG(msg);
	return (error);
}

/*
 * 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                   Cisco
 *            |                                          |                  Encapsulation
 *      ---------------------------------         --------------                  |
 *      | 0x08  | 0x81  |0xCC   |0xCF   | 0x00    |..01....    |..10....   --------------
 *      |       |       |       |       | 0x80    |            |           |0x800       |
 *     Q.933   CLNP    IP(*)   PPP(*)  SNAP     ISO 8208    ISO 8208       |            |
 *      |                    (rfc1973)  |       Modulo 8    Modulo 128     IP(*)     Others
 *      |                               |
 *      --------------------           OUI
 *      |                  |            |
 *     L2 ID              L3 ID      -------------------------
 *      |               User         |00-80-C2               |00-00-00
 *      |               specified    |                       |
 *      |               0x70        PID                     Ethertype
 *      |                            |                       |
 *      -------------------        -----------------...     ----------
 *      |0x51 |0x4E |     |0x4C    |0x7      |0xB  |        |0x806   |
 *      |     |     |     |        |         |     |        |        |
 *     7776  Q.922 Others 802.2   802.3(*)  802.6 Others    IP(*)   Others
 *
 *
 */

#define MAX_ENCAPS_HDR	8
#define OUICMP(P,A,B,C)	((P)[0]==(A) && (P)[1]==(B) && (P)[2]==(C))

static int
ng_rfc1490_rcvdata(hook_p hook, item_p item)
{
	const node_p node = NG_HOOK_NODE(hook);
	const priv_p priv = NG_NODE_PRIVATE(node);
	int error = 0;
	struct mbuf *m;

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

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

		if (priv->enc->method == NG_RFC1490_ENCAP_CISCO)
			goto switch_on_etype;

		/* 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;
switch_on_etype:		etype = ntohs(*((const u_int16_t *)ptr));
				ptr += 2;
				m_adj(m, ptr - start);
				switch (etype) {
				case ETHERTYPE_IP:
					NG_FWD_NEW_DATA(error, item,
					    priv->inet, m);
					break;
				case ETHERTYPE_ARP:
				case ETHERTYPE_REVARP:
				default:
					ERROUT(0);
				}
			} else if (OUICMP(ptr, 0x00, 0x80, 0xc2)) {
				/* 802.1 bridging */
				ptr += 3;
				if (*ptr++ != 0x00)
					ERROUT(0);	/* unknown PID octet 0 */
				if (*ptr++ != 0x07)
					ERROUT(0);	/* not FCS-less 802.3 */
				m_adj(m, ptr - start);
				NG_FWD_NEW_DATA(error, item, priv->ethernet, m);
			} else	/* Other weird stuff... */
				ERROUT(0);
			break;
		case NLPID_IP:
			m_adj(m, ptr - start);
			NG_FWD_NEW_DATA(error, item, priv->inet, m);
			break;
		case NLPID_PPP:
			m_adj(m, ptr - start);
			NG_FWD_NEW_DATA(error, item, priv->ppp, m);
			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_FWD_NEW_DATA(error, item, priv->ppp, m);
			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_FWD_NEW_DATA(error, item, priv->downlink, m);
	} else if (hook == priv->inet) {
		switch (priv->enc->method) {
		case NG_RFC1490_ENCAP_IETF_IP:
			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;
			break;
		case NG_RFC1490_ENCAP_IETF_SNAP:
			/*
			 *  According to RFC2427 frame should begin with
			 *  HDLC_UI  PAD  NLIPID  OUI      PID
			 *  03      00   80      00 00 00  08 00
			 */
			M_PREPEND(m, 8, M_NOWAIT);
			if (!m)
				ERROUT(ENOBUFS);
			mtod(m, u_char *)[0] = HDLC_UI;
			mtod(m, u_char *)[1] = 0x00;			/* PAD */
			mtod(m, u_char *)[2] = NLPID_SNAP;
			bzero((char *)(mtod(m, u_char *) + 3), 3);	/* OUI 0-0-0 */
			*((u_int16_t *)mtod(m, u_int16_t *) + 6/sizeof(u_int16_t))
			    = htons(ETHERTYPE_IP);  /* PID */
			break;
		case NG_RFC1490_ENCAP_CISCO:
			M_PREPEND(m, 2, M_NOWAIT);	/* Prepend IP ethertype */
			if (!m)
				ERROUT(ENOBUFS);
			*((u_int16_t *)mtod(m, u_int16_t *)) = htons(ETHERTYPE_IP);
			break;
		}
		NG_FWD_NEW_DATA(error, item, priv->downlink, m);
	} else if (hook == priv->ethernet) {
		M_PREPEND(m, 8, M_NOWAIT);	/* Prepend NLPID, OUI, PID */
		if (!m)
			ERROUT(ENOBUFS);
		mtod(m, u_char *)[0] = HDLC_UI;
		mtod(m, u_char *)[1] = 0x00;		/* pad */
		mtod(m, u_char *)[2] = NLPID_SNAP;
		mtod(m, u_char *)[3] = 0x00;		/* OUI */
		mtod(m, u_char *)[4] = 0x80;
		mtod(m, u_char *)[5] = 0xc2;
		mtod(m, u_char *)[6] = 0x00;		/* PID */
		mtod(m, u_char *)[7] = 0x07;
		NG_FWD_NEW_DATA(error, item, priv->downlink, m);
	} else
		panic("%s", __func__);

done:
	if (item)
		NG_FREE_ITEM(item);
	NG_FREE_M(m);
	return (error);
}

/*
 * Nuke node
 */
static int
ng_rfc1490_shutdown(node_p node)
{
	const priv_p priv = NG_NODE_PRIVATE(node);

	/* Take down netgraph node */
	bzero(priv, sizeof(*priv));
	free(priv, M_NETGRAPH);
	NG_NODE_SET_PRIVATE(node, NULL);
	NG_NODE_UNREF(node);		/* let the node escape */
	return (0);
}

/*
 * Hook disconnection
 */
static int
ng_rfc1490_disconnect(hook_p hook)
{
	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
		ng_rmnode_self(NG_HOOK_NODE(hook));
	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 if (hook == priv->ethernet)
		priv->ethernet = NULL;
	else
		panic("%s", __func__);
	return (0);
}
