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Initial revision

/*	$NetBSD: nattraversal.c,v 1.14 2011/03/14 17:18:13 tteras Exp $	*/

/*
 * Copyright (C) 2004 SuSE Linux AG, Nuernberg, Germany.
 * Contributed by: Michal Ludvig <mludvig@suse.cz>, SUSE Labs
 * 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.
 */

#include "config.h"

#include <sys/types.h>
#include <sys/param.h>

#ifdef __linux__
#include <linux/udp.h>
#endif
#if defined(__NetBSD__) || defined (__FreeBSD__)
#include <netinet/udp.h>
#endif

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <ctype.h>

#include "var.h"
#include "misc.h"
#include "vmbuf.h"
#include "plog.h"
#include "debug.h"

#include "localconf.h"
#include "remoteconf.h"
#include "sockmisc.h"
#include "isakmp_var.h"
#include "isakmp.h"
#include "oakley.h"
#include "ipsec_doi.h"
#include "vendorid.h"
#include "handler.h"
#include "crypto_openssl.h"
#include "schedule.h"
#include "nattraversal.h"
#include "grabmyaddr.h"

struct natt_ka_addrs {
  struct sockaddr	*src;
  struct sockaddr	*dst;
  unsigned		in_use;

  TAILQ_ENTRY(natt_ka_addrs) chain;
};

static TAILQ_HEAD(_natt_ka_addrs, natt_ka_addrs) ka_tree;
static struct sched sc_natt = SCHED_INITIALIZER();

/*
 * check if the given vid is NAT-T.
 */
int
natt_vendorid (int vid)
{
  return (
#ifdef ENABLE_NATT_00
	  vid == VENDORID_NATT_00 ||
#endif
#ifdef ENABLE_NATT_01
	  vid == VENDORID_NATT_01 ||
#endif
#ifdef ENABLE_NATT_02
	  vid == VENDORID_NATT_02 ||
	  vid == VENDORID_NATT_02_N ||
#endif
#ifdef ENABLE_NATT_03
	  vid == VENDORID_NATT_03 ||
#endif
#ifdef ENABLE_NATT_04
	  vid == VENDORID_NATT_04 ||
#endif
#ifdef ENABLE_NATT_05
	  vid == VENDORID_NATT_05 ||
#endif
#ifdef ENABLE_NATT_06
	  vid == VENDORID_NATT_06 ||
#endif
#ifdef ENABLE_NATT_07
	  vid == VENDORID_NATT_07 ||
#endif
#ifdef ENABLE_NATT_08
	  vid == VENDORID_NATT_08 ||
#endif
	  /* Always enable NATT RFC if ENABLE_NATT
	   */
	  vid == VENDORID_NATT_RFC);
}

vchar_t *
natt_hash_addr (struct ph1handle *iph1, struct sockaddr *addr)
{
  vchar_t *natd;
  vchar_t *buf;
  char *ptr;
  void *addr_ptr, *addr_port;
  size_t buf_size, addr_size;
  int natt_force = 0;

  if (iph1->rmconf != NULL && iph1->rmconf->nat_traversal == NATT_FORCE)
	  natt_force = 1;

  plog (LLV_INFO, LOCATION, addr, "Hashing %s with algo #%d %s\n",
	saddr2str(addr), iph1->approval->hashtype, 
	natt_force?"(NAT-T forced)":"");
  
  if (addr->sa_family == AF_INET) {
    addr_size = sizeof (struct in_addr);	/* IPv4 address */
    addr_ptr = &((struct sockaddr_in *)addr)->sin_addr;
    addr_port = &((struct sockaddr_in *)addr)->sin_port;
  }
  else if (addr->sa_family == AF_INET6) {
    addr_size = sizeof (struct in6_addr);	/* IPv6 address */
    addr_ptr = &((struct sockaddr_in6 *)addr)->sin6_addr;
    addr_port = &((struct sockaddr_in6 *)addr)->sin6_port;
  }
  else {
    plog (LLV_ERROR, LOCATION, addr, "Unsupported address family #0x%x\n", addr->sa_family);
    return NULL;
  }

  buf_size = 2 * sizeof (cookie_t);	/* CKY-I + CKY+R */
  buf_size += addr_size + 2;	/* Address + Port */
  
  if ((buf = vmalloc (buf_size)) == NULL)
    return NULL;

  ptr = buf->v;
  
  /* Copy-in CKY-I */
  memcpy (ptr, iph1->index.i_ck, sizeof (cookie_t));
  ptr += sizeof (cookie_t);
  
  /* Copy-in CKY-I */
  memcpy (ptr, iph1->index.r_ck, sizeof (cookie_t));
  ptr += sizeof (cookie_t);
  
  /* Copy-in Address (or zeroes if NATT_FORCE) */
  if (natt_force)
    memset (ptr, 0, addr_size);
  else
    memcpy (ptr, addr_ptr, addr_size);
  ptr += addr_size;

  /* Copy-in Port number */
  memcpy (ptr, addr_port, 2);

  natd = oakley_hash (buf, iph1);
  vfree(buf);

  return natd;
}

int 
natt_compare_addr_hash (struct ph1handle *iph1, vchar_t *natd_received,
			int natd_seq)
{
  vchar_t *natd_computed;
  u_int32_t flag;
  int verified = 0;

  if (iph1->rmconf != NULL &&
      iph1->rmconf->nat_traversal == NATT_FORCE)
    return verified;

  if (natd_seq == 0) {
    natd_computed = natt_hash_addr (iph1, iph1->local);
    flag = NAT_DETECTED_ME;
  }
  else {
    natd_computed = natt_hash_addr (iph1, iph1->remote);
    flag = NAT_DETECTED_PEER;
  }

  if (natd_computed == NULL) {
	plog(LLV_ERROR, LOCATION, NULL, "natd_computed allocation failed\n");
	return verified; /* XXX should abort */
  }

  if (natd_received->l == natd_computed->l &&
      memcmp (natd_received->v, natd_computed->v, natd_received->l) == 0) {
    iph1->natt_flags &= ~flag;
    verified = 1;
  }

  vfree (natd_computed);

  return verified;
}

int
natt_udp_encap (int encmode)
{
  return (encmode == IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_RFC || 
	  encmode == IPSECDOI_ATTR_ENC_MODE_UDPTRNS_RFC ||
	  encmode == IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_DRAFT ||
	  encmode == IPSECDOI_ATTR_ENC_MODE_UDPTRNS_DRAFT);
}

int
natt_fill_options (struct ph1natt_options *opts, int version)
{
  if (! opts)
    return -1;

  opts->version = version;

  switch (version) {
    case VENDORID_NATT_00:
    case VENDORID_NATT_01:
      opts->float_port = 0; /* No port floating for those drafts */
      opts->payload_nat_d = ISAKMP_NPTYPE_NATD_DRAFT;
      opts->payload_nat_oa = ISAKMP_NPTYPE_NATOA_DRAFT;
      opts->mode_udp_tunnel = IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_DRAFT;
      opts->mode_udp_transport = IPSECDOI_ATTR_ENC_MODE_UDPTRNS_DRAFT;
      opts->encaps_type = UDP_ENCAP_ESPINUDP_NON_IKE;
		break;

    case VENDORID_NATT_02:
    case VENDORID_NATT_02_N:
    case VENDORID_NATT_03:
      opts->float_port = lcconf->port_isakmp_natt;
      opts->payload_nat_d = ISAKMP_NPTYPE_NATD_DRAFT;
      opts->payload_nat_oa = ISAKMP_NPTYPE_NATOA_DRAFT;
      opts->mode_udp_tunnel = IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_DRAFT;
      opts->mode_udp_transport = IPSECDOI_ATTR_ENC_MODE_UDPTRNS_DRAFT;
      opts->encaps_type = UDP_ENCAP_ESPINUDP;
      break;
    case VENDORID_NATT_04:
    case VENDORID_NATT_05:
    case VENDORID_NATT_06:
    case VENDORID_NATT_07:
    case VENDORID_NATT_08:
      opts->float_port = lcconf->port_isakmp_natt;
      opts->payload_nat_d = ISAKMP_NPTYPE_NATD_BADDRAFT;
      opts->payload_nat_oa = ISAKMP_NPTYPE_NATOA_BADDRAFT;
      opts->mode_udp_tunnel = IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_RFC;
      opts->mode_udp_transport = IPSECDOI_ATTR_ENC_MODE_UDPTRNS_RFC;
      opts->encaps_type = UDP_ENCAP_ESPINUDP;
      break;
    case VENDORID_NATT_RFC:
      opts->float_port = lcconf->port_isakmp_natt;
      opts->payload_nat_d = ISAKMP_NPTYPE_NATD_RFC;
      opts->payload_nat_oa = ISAKMP_NPTYPE_NATOA_RFC;
      opts->mode_udp_tunnel = IPSECDOI_ATTR_ENC_MODE_UDPTUNNEL_RFC;
      opts->mode_udp_transport = IPSECDOI_ATTR_ENC_MODE_UDPTRNS_RFC;
      opts->encaps_type = UDP_ENCAP_ESPINUDP;
	  break;
    default:
      plog(LLV_ERROR, LOCATION, NULL, 
	   "unsupported NAT-T version: %s\n",
	   vid_string_by_id(version));
      return -1;
  }
 
  opts->mode_udp_diff = opts->mode_udp_tunnel - IPSECDOI_ATTR_ENC_MODE_TUNNEL;

  return 0;
}

void
natt_float_ports (struct ph1handle *iph1)
{
	if (! (iph1->natt_flags & NAT_DETECTED) )
		return;
	if (! iph1->natt_options->float_port){
		/* Drafts 00 / 01, just schedule keepalive */
		natt_keepalive_add_ph1 (iph1);
		return;
	}
	
	set_port (iph1->local, iph1->natt_options->float_port);
	set_port (iph1->remote, iph1->natt_options->float_port);
	iph1->natt_flags |= NAT_PORTS_CHANGED | NAT_ADD_NON_ESP_MARKER;
	
	natt_keepalive_add_ph1 (iph1);
}

static int
natt_is_enabled (struct remoteconf *rmconf, void *args)
{
  if (rmconf->nat_traversal)
    return 1;
  return 0;
}

void
natt_handle_vendorid (struct ph1handle *iph1, int vid_numeric)
{
  if (iph1->rmconf == NULL) {
    /* Check if any candidate remote conf allows nat-t */
    struct rmconfselector rmconf;
    rmconf_selector_from_ph1(&rmconf, iph1);
    if (enumrmconf(&rmconf, natt_is_enabled, NULL) == 0)
      return;
  } else {
    if (!iph1->rmconf->nat_traversal)
      return;
  }

  if (! iph1->natt_options)
    iph1->natt_options = racoon_calloc (1, sizeof (*iph1->natt_options));

  if (! iph1->natt_options) {
    plog (LLV_ERROR, LOCATION, NULL,
	  "Allocating memory for natt_options failed!\n");
    return;
  }
  
  if (iph1->natt_options->version < vid_numeric)
    if (natt_fill_options (iph1->natt_options, vid_numeric) == 0)
      iph1->natt_flags |= NAT_ANNOUNCED;
}

static void
natt_keepalive_delete (struct natt_ka_addrs *ka)
{
  TAILQ_REMOVE (&ka_tree, ka, chain);
  racoon_free (ka->src);
  racoon_free (ka->dst);
  racoon_free (ka);
}

/* NAT keepalive functions */
static void
natt_keepalive_send (struct sched *param)
{
  struct natt_ka_addrs	*ka, *next = NULL;
  char keepalive_packet[] = { 0xff };
  size_t len;
  int s;

  for (ka = TAILQ_FIRST(&ka_tree); ka; ka = next) {
    next = TAILQ_NEXT(ka, chain);
    
    s = myaddr_getfd(ka->src);
    if (s == -1) {
      natt_keepalive_delete(ka);
      continue;
    }
    plog (LLV_DEBUG, LOCATION, NULL, "KA: %s\n", 
	  saddr2str_fromto("%s->%s", ka->src, ka->dst));
    len = sendfromto(s, keepalive_packet, sizeof (keepalive_packet),
		     ka->src, ka->dst, 1);
    if (len == -1)
      plog(LLV_ERROR, LOCATION, NULL, "KA: sendfromto failed: %s\n",
	   strerror (errno));
  }
  
  sched_schedule (&sc_natt, lcconf->natt_ka_interval, natt_keepalive_send);
}

void
natt_keepalive_init (void)
{
  TAILQ_INIT(&ka_tree);

  /* To disable sending KAs set natt_ka_interval=0 */
  if (lcconf->natt_ka_interval > 0)
    sched_schedule (&sc_natt, lcconf->natt_ka_interval, natt_keepalive_send);
}

int
natt_keepalive_add (struct sockaddr *src, struct sockaddr *dst)
{
  struct natt_ka_addrs *ka = NULL, *new_addr;
  
  TAILQ_FOREACH (ka, &ka_tree, chain) {
    if (cmpsaddr(ka->src, src) == CMPSADDR_MATCH &&
	cmpsaddr(ka->dst, dst) == CMPSADDR_MATCH) {
      ka->in_use++;
      plog (LLV_INFO, LOCATION, NULL, "KA found: %s (in_use=%u)\n",
	    saddr2str_fromto("%s->%s", src, dst), ka->in_use);
      return 0;
    }
  }

  plog (LLV_INFO, LOCATION, NULL, "KA list add: %s\n", saddr2str_fromto("%s->%s", src, dst));

  new_addr = (struct natt_ka_addrs *)racoon_malloc(sizeof(*new_addr));
  if (! new_addr) {
    plog (LLV_ERROR, LOCATION, NULL, "Can't allocate new KA list item\n");
    return -1;
  }

  if ((new_addr->src = dupsaddr(src)) == NULL) {
	racoon_free(new_addr);
    	plog (LLV_ERROR, LOCATION, NULL, "Can't allocate new KA list item\n");
	return -1;
  }
  if ((new_addr->dst = dupsaddr(dst)) == NULL) {
	racoon_free(new_addr);
    	plog (LLV_ERROR, LOCATION, NULL, "Can't allocate new KA list item\n");
	return -1;
  }
  new_addr->in_use = 1;
  TAILQ_INSERT_TAIL(&ka_tree, new_addr, chain);

  return 0;
}

int
natt_keepalive_add_ph1 (struct ph1handle *iph1)
{
  int ret = 0;
  
  /* Should only the NATed host send keepalives?
     If yes, add '(iph1->natt_flags & NAT_DETECTED_ME)'
     to the following condition. */
  if (iph1->natt_flags & NAT_DETECTED &&
      ! (iph1->natt_flags & NAT_KA_QUEUED)) {
    ret = natt_keepalive_add (iph1->local, iph1->remote);
    if (ret == 0)
      iph1->natt_flags |= NAT_KA_QUEUED;
  }

  return ret;
}

void
natt_keepalive_remove (struct sockaddr *src, struct sockaddr *dst)
{
  struct natt_ka_addrs *ka, *next = NULL;

  plog (LLV_INFO, LOCATION, NULL, "KA remove: %s\n", saddr2str_fromto("%s->%s", src, dst));

  for (ka = TAILQ_FIRST(&ka_tree); ka; ka = next) {
    next = TAILQ_NEXT(ka, chain);
 
    plog (LLV_DEBUG, LOCATION, NULL, "KA tree dump: %s (in_use=%u)\n",
	  saddr2str_fromto("%s->%s", src, dst), ka->in_use);

    if (cmpsaddr(ka->src, src) == CMPSADDR_MATCH &&
	cmpsaddr(ka->dst, dst) == CMPSADDR_MATCH &&
	-- ka->in_use <= 0) {

      plog (LLV_DEBUG, LOCATION, NULL, "KA removing this one...\n");

      natt_keepalive_delete (ka);
      /* Should we break here? Every pair of addresses should 
         be inserted only once, but who knows :-) Lets traverse 
	 the whole list... */
    }
  }
}

static int
natt_enabled_in_rmconf_stub (struct remoteconf *rmconf, void *data)
{
  return rmconf->nat_traversal ? 1 : 0;
}

int
natt_enabled_in_rmconf ()
{
  return enumrmconf(NULL, natt_enabled_in_rmconf_stub, NULL) != 0;
}


struct payload_list *
isakmp_plist_append_natt_vids (struct payload_list *plist, vchar_t *vid_natt[MAX_NATT_VID_COUNT]){
	int i, vid_natt_i = 0;

	if(vid_natt == NULL)
		return NULL;

	for (i = 0; i < MAX_NATT_VID_COUNT; i++)
		vid_natt[i]=NULL;
	
	/* Puts the olders VIDs last, as some implementations may choose the first
	 * NATT VID given
	 */

	/* Always set RFC VID
	 */
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_RFC)) != NULL)
		vid_natt_i++;
#ifdef ENABLE_NATT_08
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_08)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_07
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_07)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_06
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_06)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_05
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_05)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_04
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_04)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_03
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_03)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_02
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_02)) != NULL)
		vid_natt_i++;
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_02_N)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_01
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_01)) != NULL)
		vid_natt_i++;
#endif
#ifdef ENABLE_NATT_00
	if ((vid_natt[vid_natt_i] = set_vendorid(VENDORID_NATT_00)) != NULL)
		vid_natt_i++;
#endif
	/* set VID payload for NAT-T */
	for (i = 0; i < vid_natt_i; i++)
		plist = isakmp_plist_append(plist, vid_natt[i], ISAKMP_NPTYPE_VID);
	
	return plist;
}