text: /*	$FreeBSD: src/sys/netinet6/ipcomp_output.c,v 1.1.2.4 2003/04/29 08:33:50 suz Exp $	*/
  /*	$KAME: ipcomp_output.c,v 1.25 2002/06/09 14:44:00 itojun Exp $	*/
  
  /*
   * Copyright (C) 1999 WIDE Project.
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the project nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON 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 ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  /*
   * RFC2393 IP payload compression protocol (IPComp).
   */
  
  #include "opt_inet.h"
  #include "opt_inet6.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/domain.h>
  #include <sys/protosw.h>
  #include <sys/socket.h>
  #include <sys/errno.h>
  #include <sys/time.h>
  #include <sys/syslog.h>
  
  #include <net/if.h>
  #include <net/route.h>
  #include <net/netisr.h>
  #include <machine/cpu.h>
  
  #include <netinet/in.h>
  #include <netinet/in_systm.h>
  #include <netinet/in_var.h>
  #include <netinet/ip.h>
  #include <netinet/ip_var.h>
  #include <netinet/ip_ecn.h>
  
  #ifdef INET6
  #include <netinet/ip6.h>
  #include <netinet6/ip6_var.h>
  #endif
  #include <netinet6/ipcomp.h>
  #ifdef INET6
  #include <netinet6/ipcomp6.h>
  #endif
  
  #include <netinet6/ipsec.h>
  #ifdef INET6
  #include <netinet6/ipsec6.h>
  #endif
  #include <netproto/key/key.h>
  #include <netproto/key/keydb.h>
  
  #include <machine/stdarg.h>
  
  #include <net/net_osdep.h>
  
  static int ipcomp_output (struct mbuf *, u_char *, struct mbuf *,
  	struct ipsecrequest *, int);
  
  /*
   * Modify the packet so that the payload is compressed.
   * The mbuf (m) must start with IPv4 or IPv6 header.
   * On failure, free the given mbuf and return non-zero.
   *
   * on invocation:
   *	m   nexthdrp md
   *	v   v        v
   *	IP ......... payload
   * during the encryption:
   *	m   nexthdrp mprev md
   *	v   v        v     v
   *	IP ............... ipcomp payload
   *	                   <-----><----->
   *	                   complen  plen
   *	<-> hlen
   *	<-----------------> compoff
   */
  static int
  ipcomp_output(struct mbuf *m, u_char *nexthdrp, struct mbuf *md,
  	      struct ipsecrequest *isr, int af)
  {
  	struct mbuf *n;
  	struct mbuf *md0;
  	struct mbuf *mcopy;
  	struct mbuf *mprev;
  	struct ipcomp *ipcomp;
  	struct secasvar *sav = isr->sav;
  	const struct ipcomp_algorithm *algo;
  	u_int16_t cpi;		/* host order */
  	size_t plen0, plen;	/* payload length to be compressed */
  	size_t compoff;
  	int afnumber;
  	int error = 0;
  	struct ipsecstat *stat;
  
  	switch (af) {
  #ifdef INET
  	case AF_INET:
  		afnumber = 4;
  		stat = &ipsecstat;
  		break;
  #endif
  #ifdef INET6
  	case AF_INET6:
  		afnumber = 6;
  		stat = &ipsec6stat;
  		break;
  #endif
  	default:
  		ipseclog((LOG_ERR, "ipcomp_output: unsupported af %d\n", af));
  		return 0;	/* no change at all */
  	}
  
  	/* grab parameters */
  	algo = ipcomp_algorithm_lookup(sav->alg_enc);
  	if ((ntohl(sav->spi) & ~0xffff) != 0 || !algo) {
  		stat->out_inval++;
  		m_freem(m);
  		return EINVAL;
  	}
  	if ((sav->flags & SADB_X_EXT_RAWCPI) == 0)
  		cpi = sav->alg_enc;
  	else
  		cpi = ntohl(sav->spi) & 0xffff;
  
  	/* compute original payload length */
  	plen = 0;
  	for (n = md; n; n = n->m_next)
  		plen += n->m_len;
  
  	/* if the payload is short enough, we don't need to compress */
  	if (plen < algo->minplen)
  		return 0;
  
  	/*
  	 * retain the original packet for two purposes:
  	 * (1) we need to backout our changes when compression is not necessary.
  	 * (2) byte lifetime computation should use the original packet.
  	 *     see RFC2401 page 23.
  	 * compromise two m_copym().  we will be going through every byte of
  	 * the payload during compression process anyways.
  	 */
  	mcopy = m_copym(m, 0, M_COPYALL, M_NOWAIT);
  	if (mcopy == NULL) {
  		error = ENOBUFS;
  		return 0;
  	}
  	md0 = m_copym(md, 0, M_COPYALL, M_NOWAIT);
  	if (md0 == NULL) {
  		m_freem(mcopy);
  		error = ENOBUFS;
  		return 0;
  	}
  	plen0 = plen;
  
  	/* make the packet over-writable */
  	for (mprev = m; mprev && mprev->m_next != md; mprev = mprev->m_next)
  		;
  	if (mprev == NULL || mprev->m_next != md) {
  		ipseclog((LOG_DEBUG, "ipcomp%d_output: md is not in chain\n",
  		    afnumber));
  		stat->out_inval++;
  		m_freem(m);
  		m_freem(md0);
  		m_freem(mcopy);
  		return EINVAL;
  	}
  	mprev->m_next = NULL;
  	if ((md = ipsec_copypkt(md)) == NULL) {
  		m_freem(m);
  		m_freem(md0);
  		m_freem(mcopy);
  		error = ENOBUFS;
  		goto fail;
  	}
  	mprev->m_next = md;
  
  	/* compress data part */
  	if ((*algo->compress)(m, md, &plen) || mprev->m_next == NULL) {
  		ipseclog((LOG_ERR, "packet compression failure\n"));
  		m = NULL;
  		m_freem(md0);
  		m_freem(mcopy);
  		stat->out_inval++;
  		error = EINVAL;
  		goto fail;
  	}
  	stat->out_comphist[sav->alg_enc]++;
  	md = mprev->m_next;
  
  	/*
  	 * if the packet became bigger, meaningless to use IPComp.
  	 * we've only wasted our cpu time.
  	 */
  	if (plen0 < plen) {
  		m_freem(md);
  		m_freem(mcopy);
  		mprev->m_next = md0;
  		return 0;
  	}
  
  	/*
  	 * no need to backout change beyond here.
  	 */
  	m_freem(md0);
  	md0 = NULL;
  
  	m->m_pkthdr.len -= plen0;
  	m->m_pkthdr.len += plen;
  
      {
  	/*
  	 * insert IPComp header.
  	 */
  #ifdef INET
  	struct ip *ip = NULL;
  #endif
  	size_t complen = sizeof(struct ipcomp);
  
  	switch (af) {
  #ifdef INET
  	case AF_INET:
  		ip = mtod(m, struct ip *);
  		break;
  #endif
  #ifdef INET6
  	case AF_INET6:
  		break;
  #endif
  	}
  
  	compoff = m->m_pkthdr.len - plen;
  
  	/*
  	 * grow the mbuf to accomodate ipcomp header.
  	 * before: IP ... payload
  	 * after:  IP ... ipcomp payload
  	 */
  	if (M_LEADINGSPACE(md) < complen) {
  		MGET(n, M_NOWAIT, MT_DATA);
  		if (!n) {
  			m_freem(m);
  			error = ENOBUFS;
  			goto fail;
  		}
  		n->m_len = complen;
  		mprev->m_next = n;
  		n->m_next = md;
  		m->m_pkthdr.len += complen;
  		ipcomp = mtod(n, struct ipcomp *);
  	} else {
  		md->m_len += complen;
  		md->m_data -= complen;
  		m->m_pkthdr.len += complen;
  		ipcomp = mtod(md, struct ipcomp *);
  	}
  
  	bzero(ipcomp, sizeof(*ipcomp));
  	ipcomp->comp_nxt = *nexthdrp;
  	*nexthdrp = IPPROTO_IPCOMP;
  	ipcomp->comp_cpi = htons(cpi);
  	switch (af) {
  #ifdef INET
  	case AF_INET:
  		if (compoff + complen + plen < IP_MAXPACKET)
  			ip->ip_len = htons(compoff + complen + plen);
  		else {
  			ipseclog((LOG_ERR,
  			    "IPv4 ESP output: size exceeds limit\n"));
  			ipsecstat.out_inval++;
  			m_freem(m);
  			error = EMSGSIZE;
  			goto fail;
  		}
  		break;
  #endif
  #ifdef INET6
  	case AF_INET6:
  		/* total packet length will be computed in ip6_output() */
  		break;
  #endif
  	}
      }
  
  	if (!m) {
  		ipseclog((LOG_DEBUG,
  		    "NULL mbuf after compression in ipcomp%d_output",
  		    afnumber));
  		stat->out_inval++;
  	}
  		stat->out_success++;
  
  	/* compute byte lifetime against original packet */
  	key_sa_recordxfer(sav, mcopy);
  	m_freem(mcopy);
  
  	return 0;
  
  fail:
  #if 1
  	return error;
  #else
  	panic("something bad in ipcomp_output");
  #endif
  }
  
  #ifdef INET
  int
  ipcomp4_output(struct mbuf *m, struct ipsecrequest *isr)
  {
  	struct ip *ip;
  	if (m->m_len < sizeof(struct ip)) {
  		ipseclog((LOG_DEBUG, "ipcomp4_output: first mbuf too short\n"));
  		ipsecstat.out_inval++;
  		m_freem(m);
  		return 0;
  	}
  	ip = mtod(m, struct ip *);
  	/* XXX assumes that m->m_next points to payload */
  	return ipcomp_output(m, &ip->ip_p, m->m_next, isr, AF_INET);
  }
  #endif /* INET */
  
  #ifdef INET6
  int
  ipcomp6_output(struct mbuf *m, u_char *nexthdrp, struct mbuf *md,
  	       struct ipsecrequest *isr)
  {
  	if (m->m_len < sizeof(struct ip6_hdr)) {
  		ipseclog((LOG_DEBUG, "ipcomp6_output: first mbuf too short\n"));
  		ipsec6stat.out_inval++;
  		m_freem(m);
  		return 0;
  	}
  	return ipcomp_output(m, nexthdrp, md, isr, AF_INET6);
  }
  #endif /* INET6 */
  