text: 
  /*
   * ng_vjc.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: Archie Cobbs <archie@freebsd.org>
   *
   * $FreeBSD: src/sys/netgraph/ng_vjc.c,v 1.9.2.5 2002/07/02 23:44:03 archie Exp $
   * $Whistle: ng_vjc.c,v 1.17 1999/11/01 09:24:52 julian Exp $
   */
  
  /*
   * This node performs Van Jacobson IP header (de)compression.
   * You must have included net/slcompress.c in your kernel compilation.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/errno.h>
  #include <sys/kernel.h>
  #include <sys/mbuf.h>
  #include <sys/malloc.h>
  #include <sys/errno.h>
  
  #include <netgraph/ng_message.h>
  #include <netgraph/netgraph.h>
  #include <netgraph/ng_parse.h>
  #include "ng_vjc.h"
  
  #include <netinet/in.h>
  #include <netinet/in_systm.h>
  #include <netinet/ip.h>
  #include <netinet/tcp.h>
  
  #include <net/slcompress.h>
  
  /* Check agreement with slcompress.c */
  #if MAX_STATES != NG_VJC_MAX_CHANNELS
  #error NG_VJC_MAX_CHANNELS must be the same as MAX_STATES
  #endif
  
  /* Maximum length of a compressed TCP VJ header */
  #define MAX_VJHEADER		19
  
  /* Node private data */
  struct ng_vjc_private {
  	struct	ngm_vjc_config conf;
  	struct	slcompress slc;
  	hook_p	ip;
  	hook_p	vjcomp;
  	hook_p	vjuncomp;
  	hook_p	vjip;
  };
  typedef struct ng_vjc_private *priv_p;
  
  #define ERROUT(x)	do { error = (x); goto done; } while (0)
  
  /* Netgraph node methods */
  static ng_constructor_t	ng_vjc_constructor;
  static ng_rcvmsg_t	ng_vjc_rcvmsg;
  static ng_shutdown_t	ng_vjc_rmnode;
  static ng_newhook_t	ng_vjc_newhook;
  static ng_rcvdata_t	ng_vjc_rcvdata;
  static ng_disconnect_t	ng_vjc_disconnect;
  
  /* Helper stuff */
  static struct mbuf *ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP);
  
  /* Parse type for struct ngm_vjc_config */
  static const struct ng_parse_struct_field ng_vjc_config_type_fields[]
  	= NG_VJC_CONFIG_TYPE_INFO;
  static const struct ng_parse_type ng_vjc_config_type = {
  	&ng_parse_struct_type,
  	&ng_vjc_config_type_fields
  };
  
  /* Parse type for the 'last_cs' and 'cs_next' fields in struct slcompress,
     which are pointers converted to integer indices, so parse them that way. */
  #ifndef __LP64__
  #define NG_VJC_TSTATE_PTR_TYPE	&ng_parse_uint32_type
  #else
  #define NG_VJC_TSTATE_PTR_TYPE	&ng_parse_uint64_type
  #endif
  
  /* Parse type for the 'cs_hdr' field in a struct cstate. Ideally we would
     like to use a 'struct ip' type instead of a simple array of bytes. */
  static const struct ng_parse_fixedarray_info ng_vjc_cs_hdr_type_info = {
  	&ng_parse_hint8_type,
  	MAX_HDR
  };
  static const struct ng_parse_type ng_vjc_cs_hdr_type = {
  	&ng_parse_fixedarray_type,
  	&ng_vjc_cs_hdr_type_info
  };
  
  /* Parse type for a struct cstate */
  static const struct ng_parse_struct_field ng_vjc_cstate_type_fields[] = {
  	{ "cs_next",		NG_VJC_TSTATE_PTR_TYPE		},
  	{ "cs_hlen",		&ng_parse_uint16_type		},
  	{ "cs_id",		&ng_parse_uint8_type		},
  	{ "cs_filler",		&ng_parse_uint8_type		},
  	{ "cs_hdr",		&ng_vjc_cs_hdr_type		},
  	{ NULL }
  };
  static const struct ng_parse_type ng_vjc_cstate_type = {
  	&ng_parse_struct_type,
  	&ng_vjc_cstate_type_fields
  };
  
  /* Parse type for an array of MAX_STATES struct cstate's, ie, tstate & rstate */
  static const struct ng_parse_fixedarray_info ng_vjc_cstatearray_type_info = {
  	&ng_vjc_cstate_type,
  	MAX_STATES
  };
  static const struct ng_parse_type ng_vjc_cstatearray_type = {
  	&ng_parse_fixedarray_type,
  	&ng_vjc_cstatearray_type_info
  };
  
  /* Parse type for struct slcompress. Keep this in sync with the
     definition of struct slcompress defined in <net/slcompress.h> */
  static const struct ng_parse_struct_field ng_vjc_slcompress_type_fields[] = {
  	{ "last_cs",		NG_VJC_TSTATE_PTR_TYPE		},
  	{ "last_recv",		&ng_parse_uint8_type		},
  	{ "last_xmit",		&ng_parse_uint8_type		},
  	{ "flags",		&ng_parse_hint16_type		},
  #ifndef SL_NO_STATS
  	{ "sls_packets",	&ng_parse_uint32_type		},
  	{ "sls_compressed",	&ng_parse_uint32_type		},
  	{ "sls_searches",	&ng_parse_uint32_type		},
  	{ "sls_misses",		&ng_parse_uint32_type		},
  	{ "sls_uncompressedin",	&ng_parse_uint32_type		},
  	{ "sls_compressedin",	&ng_parse_uint32_type		},
  	{ "sls_errorin",	&ng_parse_uint32_type		},
  	{ "sls_tossed",		&ng_parse_uint32_type		},
  #endif
  	{ "tstate",		&ng_vjc_cstatearray_type	},
  	{ "rstate",		&ng_vjc_cstatearray_type	},
  	{ NULL }
  };
  static const struct ng_parse_type ng_vjc_slcompress_type = {
  	&ng_parse_struct_type,
  	&ng_vjc_slcompress_type_fields
  };
  
  /* List of commands and how to convert arguments to/from ASCII */
  static const struct ng_cmdlist ng_vjc_cmds[] = {
  	{
  	  NGM_VJC_COOKIE,
  	  NGM_VJC_SET_CONFIG,
  	  "setconfig",
  	  &ng_vjc_config_type,
  	  NULL
  	},
  	{
  	  NGM_VJC_COOKIE,
  	  NGM_VJC_GET_CONFIG,
  	  "getconfig",
  	  NULL,
  	  &ng_vjc_config_type,
  	},
  	{
  	  NGM_VJC_COOKIE,
  	  NGM_VJC_GET_STATE,
  	  "getstate",
  	  NULL,
  	  &ng_vjc_slcompress_type,
  	},
  	{
  	  NGM_VJC_COOKIE,
  	  NGM_VJC_CLR_STATS,
  	  "clrstats",
  	  NULL,
  	  NULL,
  	},
  	{
  	  NGM_VJC_COOKIE,
  	  NGM_VJC_RECV_ERROR,
  	  "recverror",
  	  NULL,
  	  NULL,
  	},
  	{ 0 }
  };
  
  /* Node type descriptor */
  static struct ng_type ng_vjc_typestruct = {
  	NG_VERSION,
  	NG_VJC_NODE_TYPE,
  	NULL,
  	ng_vjc_constructor,
  	ng_vjc_rcvmsg,
  	ng_vjc_rmnode,
  	ng_vjc_newhook,
  	NULL,
  	NULL,
  	ng_vjc_rcvdata,
  	ng_vjc_rcvdata,
  	ng_vjc_disconnect,
  	ng_vjc_cmds
  };
  NETGRAPH_INIT(vjc, &ng_vjc_typestruct);
  
  /************************************************************************
  			NETGRAPH NODE METHODS
   ************************************************************************/
  
  /*
   * Create a new node
   */
  static int
  ng_vjc_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(&ng_vjc_typestruct, nodep))) {
  		kfree(priv, M_NETGRAPH);
  		return (error);
  	}
  	(*nodep)->private = priv;
  
  	/* Done */
  	return (0);
  }
  
  /*
   * Add a new hook
   */
  static int
  ng_vjc_newhook(node_p node, hook_p hook, const char *name)
  {
  	const priv_p priv = (priv_p) node->private;
  	hook_p *hookp;
  
  	/* Get hook */
  	if (strcmp(name, NG_VJC_HOOK_IP) == 0)
  		hookp = &priv->ip;
  	else if (strcmp(name, NG_VJC_HOOK_VJCOMP) == 0)
  		hookp = &priv->vjcomp;
  	else if (strcmp(name, NG_VJC_HOOK_VJUNCOMP) == 0)
  		hookp = &priv->vjuncomp;
  	else if (strcmp(name, NG_VJC_HOOK_VJIP) == 0)
  		hookp = &priv->vjip;
  	else
  		return (EINVAL);
  
  	/* See if already connected */
  	if (*hookp)
  		return (EISCONN);
  
  	/* OK */
  	*hookp = hook;
  	return (0);
  }
  
  /*
   * Receive a control message
   */
  static int
  ng_vjc_rcvmsg(node_p node, struct ng_mesg *msg,
  	      const char *raddr, struct ng_mesg **rptr)
  {
  	const priv_p priv = (priv_p) node->private;
  	struct ng_mesg *resp = NULL;
  	int error = 0;
  
  	/* Check type cookie */
  	switch (msg->header.typecookie) {
  	case NGM_VJC_COOKIE:
  		switch (msg->header.cmd) {
  		case NGM_VJC_SET_CONFIG:
  		    {
  			struct ngm_vjc_config *const c =
  				(struct ngm_vjc_config *) msg->data;
  
  			if (msg->header.arglen != sizeof(*c))
  				ERROUT(EINVAL);
  			if ((priv->conf.enableComp || priv->conf.enableDecomp)
  			    && (c->enableComp || c->enableDecomp))
  				ERROUT(EALREADY);
  			if (c->enableComp) {
  				if (c->maxChannel > NG_VJC_MAX_CHANNELS - 1
  				    || c->maxChannel < NG_VJC_MIN_CHANNELS - 1)
  					ERROUT(EINVAL);
  			} else
  				c->maxChannel = NG_VJC_MAX_CHANNELS - 1;
  			if (c->enableComp != 0 || c->enableDecomp != 0) {
  				bzero(&priv->slc, sizeof(priv->slc));
  				sl_compress_init(&priv->slc, c->maxChannel);
  			}
  			priv->conf = *c;
  			break;
  		    }
  		case NGM_VJC_GET_CONFIG:
  		    {
  			struct ngm_vjc_config *conf;
  
  			NG_MKRESPONSE(resp, msg, sizeof(*conf), M_NOWAIT);
  			if (resp == NULL)
  				ERROUT(ENOMEM);
  			conf = (struct ngm_vjc_config *)resp->data;
  			*conf = priv->conf;
  			break;
  		    }
  		case NGM_VJC_GET_STATE:
  		    {
  			const struct slcompress *const sl0 = &priv->slc;
  			struct slcompress *sl;
  			u_int16_t index;
  			int i;
  
  			/* Get response structure */
  			NG_MKRESPONSE(resp, msg, sizeof(*sl), M_NOWAIT);
  			if (resp == NULL)
  				ERROUT(ENOMEM);
  			sl = (struct slcompress *)resp->data;
  			*sl = *sl0;
  
  			/* Replace pointers with integer indicies */
  			if (sl->last_cs != NULL) {
  				index = sl0->last_cs - sl0->tstate;
  				bzero(&sl->last_cs, sizeof(sl->last_cs));
  				*((u_int16_t *)&sl->last_cs) = index;
  			}
  			for (i = 0; i < MAX_STATES; i++) {
  				struct cstate *const cs = &sl->tstate[i];
  
  				index = sl0->tstate[i].cs_next - sl0->tstate;
  				bzero(&cs->cs_next, sizeof(cs->cs_next));
  				*((u_int16_t *)&cs->cs_next) = index;
  			}
  			break;
  		    }
  		case NGM_VJC_CLR_STATS:
  			priv->slc.sls_packets = 0;
  			priv->slc.sls_compressed = 0;
  			priv->slc.sls_searches = 0;
  			priv->slc.sls_misses = 0;
  			priv->slc.sls_uncompressedin = 0;
  			priv->slc.sls_compressedin = 0;
  			priv->slc.sls_errorin = 0;
  			priv->slc.sls_tossed = 0;
  			break;
  		case NGM_VJC_RECV_ERROR:
  			sl_uncompress_tcp(NULL, 0, TYPE_ERROR, &priv->slc);
  			break;
  		default:
  			error = EINVAL;
  			break;
  		}
  		break;
  	default:
  		error = EINVAL;
  		break;
  	}
  	if (rptr)
  		*rptr = resp;
  	else if (resp)
  		kfree(resp, M_NETGRAPH);
  
  done:
  	kfree(msg, M_NETGRAPH);
  	return (error);
  }
  
  /*
   * Receive data
   */
  static int
  ng_vjc_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  {
  	const node_p node = hook->node;
  	const priv_p priv = (priv_p) node->private;
  	int error = 0;
  
  	if (hook == priv->ip) {			/* outgoing packet */
  		u_int type = TYPE_IP;
  
  		/* Compress packet if enabled and proto is TCP */
  		if (priv->conf.enableComp) {
  			struct ip *ip;
  
  			if ((m = ng_vjc_pulluphdrs(m, 0)) == NULL) {
  				NG_FREE_META(meta);
  				return (ENOBUFS);
  			}
  			ip = mtod(m, struct ip *);
  			if (ip->ip_p == IPPROTO_TCP) {
  				const int origLen = m->m_len;
  
  				type = sl_compress_tcp(m, ip,
  				    &priv->slc, priv->conf.compressCID);
  				m->m_pkthdr.len += m->m_len - origLen;
  			}
  		}
  
  		/* Dispatch to the appropriate outgoing hook */
  		switch (type) {
  		case TYPE_IP:
  			hook = priv->vjip;
  			break;
  		case TYPE_UNCOMPRESSED_TCP:
  			hook = priv->vjuncomp;
  			break;
  		case TYPE_COMPRESSED_TCP:
  			hook = priv->vjcomp;
  			break;
  		default:
  			panic("%s: type=%d", __func__, type);
  		}
  	} else if (hook == priv->vjcomp) {	/* incoming compressed packet */
  		int vjlen, need2pullup;
  		struct mbuf *hm;
  		u_char *hdr;
  		u_int hlen;
  
  		/* Are we decompressing? */
  		if (!priv->conf.enableDecomp) {
  			NG_FREE_DATA(m, meta);
  			return (ENXIO);
  		}
  
  		/* Pull up the necessary amount from the mbuf */
  		need2pullup = MAX_VJHEADER;
  		if (need2pullup > m->m_pkthdr.len)
  			need2pullup = m->m_pkthdr.len;
  		if (m->m_len < need2pullup
  		    && (m = m_pullup(m, need2pullup)) == NULL) {
  			priv->slc.sls_errorin++;
  			NG_FREE_META(meta);
  			return (ENOBUFS);
  		}
  
  		/* Uncompress packet to reconstruct TCP/IP header */
  		vjlen = sl_uncompress_tcp_core(mtod(m, u_char *),
  		    m->m_len, m->m_pkthdr.len, TYPE_COMPRESSED_TCP,
  		    &priv->slc, &hdr, &hlen);
  		if (vjlen <= 0) {
  			NG_FREE_DATA(m, meta);
  			return (EINVAL);
  		}
  		m_adj(m, vjlen);
  
  		/* Copy the reconstructed TCP/IP headers into a new mbuf */
  		MGETHDR(hm, MB_DONTWAIT, MT_DATA);
  		if (hm == NULL) {
  			priv->slc.sls_errorin++;
  			NG_FREE_DATA(m, meta);
  			return (ENOBUFS);
  		}
  		hm->m_len = 0;
  		hm->m_pkthdr.rcvif = NULL;
  		if (hlen > MHLEN) {		/* unlikely, but can happen */
  			MCLGET(hm, MB_DONTWAIT);
  			if ((hm->m_flags & M_EXT) == 0) {
  				m_freem(hm);
  				priv->slc.sls_errorin++;
  				NG_FREE_DATA(m, meta);
  				return (ENOBUFS);
  			}
  		}
  		bcopy(hdr, mtod(hm, u_char *), hlen);
  		hm->m_len = hlen;
  
  		/* Glue TCP/IP headers and rest of packet together */
  		hm->m_next = m;
  		hm->m_pkthdr.len = hlen + m->m_pkthdr.len;
  		m = hm;
  		hook = priv->ip;
  	} else if (hook == priv->vjuncomp) {	/* incoming uncompressed pkt */
  		u_char *hdr;
  		u_int hlen;
  
  		/* Are we decompressing? */
  		if (!priv->conf.enableDecomp) {
  			NG_FREE_DATA(m, meta);
  			return (ENXIO);
  		}
  
  		/* Pull up IP+TCP headers */
  		if ((m = ng_vjc_pulluphdrs(m, 1)) == NULL) {
  			NG_FREE_META(meta);
  			return (ENOBUFS);
  		}
  
  		/* Run packet through uncompressor */
  		if (sl_uncompress_tcp_core(mtod(m, u_char *),
  		    m->m_len, m->m_pkthdr.len, TYPE_UNCOMPRESSED_TCP,
  		    &priv->slc, &hdr, &hlen) < 0) {
  			NG_FREE_DATA(m, meta);
  			return (EINVAL);
  		}
  		hook = priv->ip;
  	} else if (hook == priv->vjip)	/* incoming regular packet (bypass) */
  		hook = priv->ip;
  	else
  		panic("%s: unknown hook", __func__);
  
  	/* Send result back out */
  	NG_SEND_DATA(error, hook, m, meta);
  	return (error);
  }
  
  /*
   * Shutdown node
   */
  static int
  ng_vjc_rmnode(node_p node)
  {
  	const priv_p priv = (priv_p) node->private;
  
  	node->flags |= NG_INVALID;
  	ng_cutlinks(node);
  	ng_unname(node);
  	bzero(priv, sizeof(*priv));
  	kfree(priv, M_NETGRAPH);
  	node->private = NULL;
  	ng_unref(node);
  	return (0);
  }
  
  /*
   * Hook disconnection
   */
  static int
  ng_vjc_disconnect(hook_p hook)
  {
  	const node_p node = hook->node;
  	const priv_p priv = node->private;
  
  	/* Zero out hook pointer */
  	if (hook == priv->ip)
  		priv->ip = NULL;
  	else if (hook == priv->vjcomp)
  		priv->vjcomp = NULL;
  	else if (hook == priv->vjuncomp)
  		priv->vjuncomp = NULL;
  	else if (hook == priv->vjip)
  		priv->vjip = NULL;
  	else
  		panic("%s: unknown hook", __func__);
  
  	/* Go away if no hooks left */
  	if (node->numhooks == 0)
  		ng_rmnode(node);
  	return (0);
  }
  
  /************************************************************************
  			HELPER STUFF
   ************************************************************************/
  
  /*
   * Pull up the full IP and TCP headers of a packet. If packet is not
   * a TCP packet, just pull up the IP header.
   */
  static struct mbuf *
  ng_vjc_pulluphdrs(struct mbuf *m, int knownTCP)
  {
  	struct ip *ip;
  	struct tcphdr *tcp;
  	int ihlen, thlen;
  
  	if (m->m_len < sizeof(*ip) && (m = m_pullup(m, sizeof(*ip))) == NULL)
  		return (NULL);
  	ip = mtod(m, struct ip *);
  	if (!knownTCP && ip->ip_p != IPPROTO_TCP)
  		return (m);
  	ihlen = ip->ip_hl << 2;
  	if (m->m_len < ihlen + sizeof(*tcp)) {
  		if ((m = m_pullup(m, ihlen + sizeof(*tcp))) == NULL)
  			return (NULL);
  		ip = mtod(m, struct ip *);
  	}
  	tcp = (struct tcphdr *)((u_char *)ip + ihlen);
  	thlen = tcp->th_off << 2;
  	if (m->m_len < ihlen + thlen)
  		m = m_pullup(m, ihlen + thlen);
  	return (m);
  }
  
  