/*      $NetBSD: nattraversal.c,v 1.16 2025/03/07 15:55:29 christos 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;
  uint32_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);
}

/*ARGSUSED*/
static int
natt_is_enabled(struct remoteconf *rmconf, void *args __unused)
{
        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 */
/*ARGSUSED*/
static void
natt_keepalive_send (struct sched *param __unused)
{
  struct natt_ka_addrs  *ka, *next = NULL;
  char keepalive_packet[] = { (char)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 == (size_t)-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... */
    }
  }
}

/*ARGSUSED*/
static int
natt_enabled_in_rmconf_stub (struct remoteconf *rmconf, void *data __unused)
{
  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;
}