net/ipv4/netfilter/nf_nat_h323.c

   1 /*
   2  * H.323 extension for NAT alteration.
   3  *
   4  * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
   5  * Copyright (c) 2006-2012 Patrick McHardy <kaber@trash.net>
   6  *
   7  * This source code is licensed under General Public License version 2.
   8  *
   9  * Based on the 'brute force' H.323 NAT module by
  10  * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/tcp.h>
  15 #include <net/tcp.h>
  16
  17 #include <net/netfilter/nf_nat.h>
  18 #include <net/netfilter/nf_nat_helper.h>
  19 #include <net/netfilter/nf_conntrack_helper.h>
  20 #include <net/netfilter/nf_conntrack_expect.h>
  21 #include <linux/netfilter/nf_conntrack_h323.h>
  22
  23 /****************************************************************************/
  24 static int set_addr(struct sk_buff *skb, unsigned int protoff,
  25                     unsigned char **data, int dataoff,
  26                     unsigned int addroff, __be32 ip, __be16 port)
  27 {
  28         enum ip_conntrack_info ctinfo;
  29         struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  30         struct {
  31                 __be32 ip;
  32                 __be16 port;
  33         } __attribute__ ((__packed__)) buf;
  34         const struct tcphdr *th;
  35         struct tcphdr _tcph;
  36
  37         buf.ip = ip;
  38         buf.port = port;
  39         addroff += dataoff;
  40
  41         if (ip_hdr(skb)->protocol == IPPROTO_TCP) {
  42                 if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
  43                                               protoff, addroff, sizeof(buf),
  44                                               (char *) &buf, sizeof(buf))) {
  45                         net_notice_ratelimited("nf_nat_h323: nf_nat_mangle_tcp_packet error\n");
  46                         return -1;
  47                 }
  48
  49                 /* Relocate data pointer */
  50                 th = skb_header_pointer(skb, ip_hdrlen(skb),
  51                                         sizeof(_tcph), &_tcph);
  52                 if (th == NULL)
  53                         return -1;
  54                 *data = skb->data + ip_hdrlen(skb) + th->doff * 4 + dataoff;
  55         } else {
  56                 if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
  57                                               protoff, addroff, sizeof(buf),
  58                                               (char *) &buf, sizeof(buf))) {
  59                         net_notice_ratelimited("nf_nat_h323: nf_nat_mangle_udp_packet error\n");
  60                         return -1;
  61                 }
  62                 /* nf_nat_mangle_udp_packet uses skb_make_writable() to copy
  63                  * or pull everything in a linear buffer, so we can safely
  64                  * use the skb pointers now */
  65                 *data = skb->data + ip_hdrlen(skb) + sizeof(struct udphdr);
  66         }
  67
  68         return 0;
  69 }
  70
  71 /****************************************************************************/
  72 static int set_h225_addr(struct sk_buff *skb, unsigned int protoff,
  73                          unsigned char **data, int dataoff,
  74                          TransportAddress *taddr,
  75                          union nf_inet_addr *addr, __be16 port)
  76 {
  77         return set_addr(skb, protoff, data, dataoff, taddr->ipAddress.ip,
  78                         addr->ip, port);
  79 }
  80
  81 /****************************************************************************/
  82 static int set_h245_addr(struct sk_buff *skb, unsigned protoff,
  83                          unsigned char **data, int dataoff,
  84                          H245_TransportAddress *taddr,
  85                          union nf_inet_addr *addr, __be16 port)
  86 {
  87         return set_addr(skb, protoff, data, dataoff,
  88                         taddr->unicastAddress.iPAddress.network,
  89                         addr->ip, port);
  90 }
  91
  92 /****************************************************************************/
  93 static int set_sig_addr(struct sk_buff *skb, struct nf_conn *ct,
  94                         enum ip_conntrack_info ctinfo,
  95                         unsigned int protoff, unsigned char **data,
  96                         TransportAddress *taddr, int count)
  97 {
  98         const struct nf_ct_h323_master *info = nfct_help_data(ct);
  99         int dir = CTINFO2DIR(ctinfo);
 100         int i;
 101         __be16 port;
 102         union nf_inet_addr addr;
 103
 104         for (i = 0; i < count; i++) {
 105                 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port)) {
 106                         if (addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
 107                             port == info->sig_port[dir]) {
 108                                 /* GW->GK */
 109
 110                                 /* Fix for Gnomemeeting */
 111                                 if (i > 0 &&
 112                                     get_h225_addr(ct, *data, &taddr[0],
 113                                                   &addr, &port) &&
 114                                     (ntohl(addr.ip) & 0xff000000) == 0x7f000000)
 115                                         i = 0;
 116
 117                                 pr_debug("nf_nat_ras: set signal address %pI4:%hu->%pI4:%hu\n",
 118                                          &addr.ip, port,
 119                                          &ct->tuplehash[!dir].tuple.dst.u3.ip,
 120                                          info->sig_port[!dir]);
 121                                 return set_h225_addr(skb, protoff, data, 0,
 122                                                      &taddr[i],
 123                                                      &ct->tuplehash[!dir].
 124                                                      tuple.dst.u3,
 125                                                      info->sig_port[!dir]);
 126                         } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
 127                                    port == info->sig_port[dir]) {
 128                                 /* GK->GW */
 129                                 pr_debug("nf_nat_ras: set signal address %pI4:%hu->%pI4:%hu\n",
 130                                          &addr.ip, port,
 131                                          &ct->tuplehash[!dir].tuple.src.u3.ip,
 132                                          info->sig_port[!dir]);
 133                                 return set_h225_addr(skb, protoff, data, 0,
 134                                                      &taddr[i],
 135                                                      &ct->tuplehash[!dir].
 136                                                      tuple.src.u3,
 137                                                      info->sig_port[!dir]);
 138                         }
 139                 }
 140         }
 141
 142         return 0;
 143 }
 144
 145 /****************************************************************************/
 146 static int set_ras_addr(struct sk_buff *skb, struct nf_conn *ct,
 147                         enum ip_conntrack_info ctinfo,
 148                         unsigned int protoff, unsigned char **data,
 149                         TransportAddress *taddr, int count)
 150 {
 151         int dir = CTINFO2DIR(ctinfo);
 152         int i;
 153         __be16 port;
 154         union nf_inet_addr addr;
 155
 156         for (i = 0; i < count; i++) {
 157                 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
 158                     addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
 159                     port == ct->tuplehash[dir].tuple.src.u.udp.port) {
 160                         pr_debug("nf_nat_ras: set rasAddress %pI4:%hu->%pI4:%hu\n",
 161                                  &addr.ip, ntohs(port),
 162                                  &ct->tuplehash[!dir].tuple.dst.u3.ip,
 163                                  ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port));
 164                         return set_h225_addr(skb, protoff, data, 0, &taddr[i],
 165                                              &ct->tuplehash[!dir].tuple.dst.u3,
 166                                              ct->tuplehash[!dir].tuple.
 167                                                                 dst.u.udp.port);
 168                 }
 169         }
 170
 171         return 0;
 172 }
 173
 174 /****************************************************************************/
 175 static int nat_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
 176                         enum ip_conntrack_info ctinfo,
 177                         unsigned int protoff, unsigned char **data, int dataoff,
 178                         H245_TransportAddress *taddr,
 179                         __be16 port, __be16 rtp_port,
 180                         struct nf_conntrack_expect *rtp_exp,
 181                         struct nf_conntrack_expect *rtcp_exp)
 182 {
 183         struct nf_ct_h323_master *info = nfct_help_data(ct);
 184         int dir = CTINFO2DIR(ctinfo);
 185         int i;
 186         u_int16_t nated_port;
 187
 188         /* Set expectations for NAT */
 189         rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
 190         rtp_exp->expectfn = nf_nat_follow_master;
 191         rtp_exp->dir = !dir;
 192         rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
 193         rtcp_exp->expectfn = nf_nat_follow_master;
 194         rtcp_exp->dir = !dir;
 195
 196         /* Lookup existing expects */
 197         for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
 198                 if (info->rtp_port[i][dir] == rtp_port) {
 199                         /* Expected */
 200
 201                         /* Use allocated ports first. This will refresh
 202                          * the expects */
 203                         rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
 204                         rtcp_exp->tuple.dst.u.udp.port =
 205                             htons(ntohs(info->rtp_port[i][dir]) + 1);
 206                         break;
 207                 } else if (info->rtp_port[i][dir] == 0) {
 208                         /* Not expected */
 209                         break;
 210                 }
 211         }
 212
 213         /* Run out of expectations */
 214         if (i >= H323_RTP_CHANNEL_MAX) {
 215                 net_notice_ratelimited("nf_nat_h323: out of expectations\n");
 216                 return 0;
 217         }
 218
 219         /* Try to get a pair of ports. */
 220         for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
 221              nated_port != 0; nated_port += 2) {
 222                 int ret;
 223
 224                 rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
 225                 ret = nf_ct_expect_related(rtp_exp);
 226                 if (ret == 0) {
 227                         rtcp_exp->tuple.dst.u.udp.port =
 228                             htons(nated_port + 1);
 229                         ret = nf_ct_expect_related(rtcp_exp);
 230                         if (ret == 0)
 231                                 break;
 232                         else if (ret != -EBUSY) {
 233                                 nf_ct_unexpect_related(rtp_exp);
 234                                 nated_port = 0;
 235                                 break;
 236                         }
 237                 } else if (ret != -EBUSY) {
 238                         nated_port = 0;
 239                         break;
 240                 }
 241         }
 242
 243         if (nated_port == 0) {  /* No port available */
 244                 net_notice_ratelimited("nf_nat_h323: out of RTP ports\n");
 245                 return 0;
 246         }
 247
 248         /* Modify signal */
 249         if (set_h245_addr(skb, protoff, data, dataoff, taddr,
 250                           &ct->tuplehash[!dir].tuple.dst.u3,
 251                           htons((port & htons(1)) ? nated_port + 1 :
 252                                                     nated_port)) == 0) {
 253                 /* Save ports */
 254                 info->rtp_port[i][dir] = rtp_port;
 255                 info->rtp_port[i][!dir] = htons(nated_port);
 256         } else {
 257                 nf_ct_unexpect_related(rtp_exp);
 258                 nf_ct_unexpect_related(rtcp_exp);
 259                 return -1;
 260         }
 261
 262         /* Success */
 263         pr_debug("nf_nat_h323: expect RTP %pI4:%hu->%pI4:%hu\n",
 264                  &rtp_exp->tuple.src.u3.ip,
 265                  ntohs(rtp_exp->tuple.src.u.udp.port),
 266                  &rtp_exp->tuple.dst.u3.ip,
 267                  ntohs(rtp_exp->tuple.dst.u.udp.port));
 268         pr_debug("nf_nat_h323: expect RTCP %pI4:%hu->%pI4:%hu\n",
 269                  &rtcp_exp->tuple.src.u3.ip,
 270                  ntohs(rtcp_exp->tuple.src.u.udp.port),
 271                  &rtcp_exp->tuple.dst.u3.ip,
 272                  ntohs(rtcp_exp->tuple.dst.u.udp.port));
 273
 274         return 0;
 275 }
 276
 277 /****************************************************************************/
 278 static int nat_t120(struct sk_buff *skb, struct nf_conn *ct,
 279                     enum ip_conntrack_info ctinfo,
 280                     unsigned int protoff, unsigned char **data, int dataoff,
 281                     H245_TransportAddress *taddr, __be16 port,
 282                     struct nf_conntrack_expect *exp)
 283 {
 284         int dir = CTINFO2DIR(ctinfo);
 285         u_int16_t nated_port = ntohs(port);
 286
 287         /* Set expectations for NAT */
 288         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 289         exp->expectfn = nf_nat_follow_master;
 290         exp->dir = !dir;
 291
 292         /* Try to get same port: if not, try to change it. */
 293         for (; nated_port != 0; nated_port++) {
 294                 int ret;
 295
 296                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 297                 ret = nf_ct_expect_related(exp);
 298                 if (ret == 0)
 299                         break;
 300                 else if (ret != -EBUSY) {
 301                         nated_port = 0;
 302                         break;
 303                 }
 304         }
 305
 306         if (nated_port == 0) {  /* No port available */
 307                 net_notice_ratelimited("nf_nat_h323: out of TCP ports\n");
 308                 return 0;
 309         }
 310
 311         /* Modify signal */
 312         if (set_h245_addr(skb, protoff, data, dataoff, taddr,
 313                           &ct->tuplehash[!dir].tuple.dst.u3,
 314                           htons(nated_port)) < 0) {
 315                 nf_ct_unexpect_related(exp);
 316                 return -1;
 317         }
 318
 319         pr_debug("nf_nat_h323: expect T.120 %pI4:%hu->%pI4:%hu\n",
 320                  &exp->tuple.src.u3.ip,
 321                  ntohs(exp->tuple.src.u.tcp.port),
 322                  &exp->tuple.dst.u3.ip,
 323                  ntohs(exp->tuple.dst.u.tcp.port));
 324
 325         return 0;
 326 }
 327
 328 /****************************************************************************/
 329 static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
 330                     enum ip_conntrack_info ctinfo,
 331                     unsigned int protoff, unsigned char **data, int dataoff,
 332                     TransportAddress *taddr, __be16 port,
 333                     struct nf_conntrack_expect *exp)
 334 {
 335         struct nf_ct_h323_master *info = nfct_help_data(ct);
 336         int dir = CTINFO2DIR(ctinfo);
 337         u_int16_t nated_port = ntohs(port);
 338
 339         /* Set expectations for NAT */
 340         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 341         exp->expectfn = nf_nat_follow_master;
 342         exp->dir = !dir;
 343
 344         /* Check existing expects */
 345         if (info->sig_port[dir] == port)
 346                 nated_port = ntohs(info->sig_port[!dir]);
 347
 348         /* Try to get same port: if not, try to change it. */
 349         for (; nated_port != 0; nated_port++) {
 350                 int ret;
 351
 352                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 353                 ret = nf_ct_expect_related(exp);
 354                 if (ret == 0)
 355                         break;
 356                 else if (ret != -EBUSY) {
 357                         nated_port = 0;
 358                         break;
 359                 }
 360         }
 361
 362         if (nated_port == 0) {  /* No port available */
 363                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 364                 return 0;
 365         }
 366
 367         /* Modify signal */
 368         if (set_h225_addr(skb, protoff, data, dataoff, taddr,
 369                           &ct->tuplehash[!dir].tuple.dst.u3,
 370                           htons(nated_port)) == 0) {
 371                 /* Save ports */
 372                 info->sig_port[dir] = port;
 373                 info->sig_port[!dir] = htons(nated_port);
 374         } else {
 375                 nf_ct_unexpect_related(exp);
 376                 return -1;
 377         }
 378
 379         pr_debug("nf_nat_q931: expect H.245 %pI4:%hu->%pI4:%hu\n",
 380                  &exp->tuple.src.u3.ip,
 381                  ntohs(exp->tuple.src.u.tcp.port),
 382                  &exp->tuple.dst.u3.ip,
 383                  ntohs(exp->tuple.dst.u.tcp.port));
 384
 385         return 0;
 386 }
 387
 388 /****************************************************************************
 389  * This conntrack expect function replaces nf_conntrack_q931_expect()
 390  * which was set by nf_conntrack_h323.c.
 391  ****************************************************************************/
 392 static void ip_nat_q931_expect(struct nf_conn *new,
 393                                struct nf_conntrack_expect *this)
 394 {
 395         struct nf_nat_range range;
 396
 397         if (this->tuple.src.u3.ip != 0) {       /* Only accept calls from GK */
 398                 nf_nat_follow_master(new, this);
 399                 return;
 400         }
 401
 402         /* This must be a fresh one. */
 403         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 404
 405         /* Change src to where master sends to */
 406         range.flags = NF_NAT_RANGE_MAP_IPS;
 407         range.min_addr = range.max_addr =
 408             new->tuplehash[!this->dir].tuple.src.u3;
 409         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 410
 411         /* For DST manip, map port here to where it's expected. */
 412         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 413         range.min_proto = range.max_proto = this->saved_proto;
 414         range.min_addr = range.max_addr =
 415             new->master->tuplehash[!this->dir].tuple.src.u3;
 416         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 417 }
 418
 419 /****************************************************************************/
 420 static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
 421                     enum ip_conntrack_info ctinfo,
 422                     unsigned int protoff, unsigned char **data,
 423                     TransportAddress *taddr, int idx,
 424                     __be16 port, struct nf_conntrack_expect *exp)
 425 {
 426         struct nf_ct_h323_master *info = nfct_help_data(ct);
 427         int dir = CTINFO2DIR(ctinfo);
 428         u_int16_t nated_port = ntohs(port);
 429         union nf_inet_addr addr;
 430
 431         /* Set expectations for NAT */
 432         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 433         exp->expectfn = ip_nat_q931_expect;
 434         exp->dir = !dir;
 435
 436         /* Check existing expects */
 437         if (info->sig_port[dir] == port)
 438                 nated_port = ntohs(info->sig_port[!dir]);
 439
 440         /* Try to get same port: if not, try to change it. */
 441         for (; nated_port != 0; nated_port++) {
 442                 int ret;
 443
 444                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 445                 ret = nf_ct_expect_related(exp);
 446                 if (ret == 0)
 447                         break;
 448                 else if (ret != -EBUSY) {
 449                         nated_port = 0;
 450                         break;
 451                 }
 452         }
 453
 454         if (nated_port == 0) {  /* No port available */
 455                 net_notice_ratelimited("nf_nat_ras: out of TCP ports\n");
 456                 return 0;
 457         }
 458
 459         /* Modify signal */
 460         if (set_h225_addr(skb, protoff, data, 0, &taddr[idx],
 461                           &ct->tuplehash[!dir].tuple.dst.u3,
 462                           htons(nated_port)) == 0) {
 463                 /* Save ports */
 464                 info->sig_port[dir] = port;
 465                 info->sig_port[!dir] = htons(nated_port);
 466
 467                 /* Fix for Gnomemeeting */
 468                 if (idx > 0 &&
 469                     get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
 470                     (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
 471                         set_h225_addr(skb, protoff, data, 0, &taddr[0],
 472                                       &ct->tuplehash[!dir].tuple.dst.u3,
 473                                       info->sig_port[!dir]);
 474                 }
 475         } else {
 476                 nf_ct_unexpect_related(exp);
 477                 return -1;
 478         }
 479
 480         /* Success */
 481         pr_debug("nf_nat_ras: expect Q.931 %pI4:%hu->%pI4:%hu\n",
 482                  &exp->tuple.src.u3.ip,
 483                  ntohs(exp->tuple.src.u.tcp.port),
 484                  &exp->tuple.dst.u3.ip,
 485                  ntohs(exp->tuple.dst.u.tcp.port));
 486
 487         return 0;
 488 }
 489
 490 /****************************************************************************/
 491 static void ip_nat_callforwarding_expect(struct nf_conn *new,
 492                                          struct nf_conntrack_expect *this)
 493 {
 494         struct nf_nat_range range;
 495
 496         /* This must be a fresh one. */
 497         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 498
 499         /* Change src to where master sends to */
 500         range.flags = NF_NAT_RANGE_MAP_IPS;
 501         range.min_addr = range.max_addr =
 502             new->tuplehash[!this->dir].tuple.src.u3;
 503         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 504
 505         /* For DST manip, map port here to where it's expected. */
 506         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 507         range.min_proto = range.max_proto = this->saved_proto;
 508         range.min_addr = range.max_addr = this->saved_addr;
 509         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 510 }
 511
 512 /****************************************************************************/
 513 static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 514                               enum ip_conntrack_info ctinfo,
 515                               unsigned int protoff,
 516                               unsigned char **data, int dataoff,
 517                               TransportAddress *taddr, __be16 port,
 518                               struct nf_conntrack_expect *exp)
 519 {
 520         int dir = CTINFO2DIR(ctinfo);
 521         u_int16_t nated_port;
 522
 523         /* Set expectations for NAT */
 524         exp->saved_addr = exp->tuple.dst.u3;
 525         exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
 526         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 527         exp->expectfn = ip_nat_callforwarding_expect;
 528         exp->dir = !dir;
 529
 530         /* Try to get same port: if not, try to change it. */
 531         for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
 532                 int ret;
 533
 534                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 535                 ret = nf_ct_expect_related(exp);
 536                 if (ret == 0)
 537                         break;
 538                 else if (ret != -EBUSY) {
 539                         nated_port = 0;
 540                         break;
 541                 }
 542         }
 543
 544         if (nated_port == 0) {  /* No port available */
 545                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 546                 return 0;
 547         }
 548
 549         /* Modify signal */
 550         if (!set_h225_addr(skb, protoff, data, dataoff, taddr,
 551                            &ct->tuplehash[!dir].tuple.dst.u3,
 552                            htons(nated_port)) == 0) {
 553                 nf_ct_unexpect_related(exp);
 554                 return -1;
 555         }
 556
 557         /* Success */
 558         pr_debug("nf_nat_q931: expect Call Forwarding %pI4:%hu->%pI4:%hu\n",
 559                  &exp->tuple.src.u3.ip,
 560                  ntohs(exp->tuple.src.u.tcp.port),
 561                  &exp->tuple.dst.u3.ip,
 562                  ntohs(exp->tuple.dst.u.tcp.port));
 563
 564         return 0;
 565 }
 566
 567 static struct nf_ct_helper_expectfn q931_nat = {
 568         .name           = "Q.931",
 569         .expectfn       = ip_nat_q931_expect,
 570 };
 571
 572 static struct nf_ct_helper_expectfn callforwarding_nat = {
 573         .name           = "callforwarding",
 574         .expectfn       = ip_nat_callforwarding_expect,
 575 };
 576
 577 /****************************************************************************/
 578 static int __init init(void)
 579 {
 580         BUG_ON(set_h245_addr_hook != NULL);
 581         BUG_ON(set_h225_addr_hook != NULL);
 582         BUG_ON(set_sig_addr_hook != NULL);
 583         BUG_ON(set_ras_addr_hook != NULL);
 584         BUG_ON(nat_rtp_rtcp_hook != NULL);
 585         BUG_ON(nat_t120_hook != NULL);
 586         BUG_ON(nat_h245_hook != NULL);
 587         BUG_ON(nat_callforwarding_hook != NULL);
 588         BUG_ON(nat_q931_hook != NULL);
 589
 590         RCU_INIT_POINTER(set_h245_addr_hook, set_h245_addr);
 591         RCU_INIT_POINTER(set_h225_addr_hook, set_h225_addr);
 592         RCU_INIT_POINTER(set_sig_addr_hook, set_sig_addr);
 593         RCU_INIT_POINTER(set_ras_addr_hook, set_ras_addr);
 594         RCU_INIT_POINTER(nat_rtp_rtcp_hook, nat_rtp_rtcp);
 595         RCU_INIT_POINTER(nat_t120_hook, nat_t120);
 596         RCU_INIT_POINTER(nat_h245_hook, nat_h245);
 597         RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
 598         RCU_INIT_POINTER(nat_q931_hook, nat_q931);
 599         nf_ct_helper_expectfn_register(&q931_nat);
 600         nf_ct_helper_expectfn_register(&callforwarding_nat);
 601         return 0;
 602 }
 603
 604 /****************************************************************************/
 605 static void __exit fini(void)
 606 {
 607         RCU_INIT_POINTER(set_h245_addr_hook, NULL);
 608         RCU_INIT_POINTER(set_h225_addr_hook, NULL);
 609         RCU_INIT_POINTER(set_sig_addr_hook, NULL);
 610         RCU_INIT_POINTER(set_ras_addr_hook, NULL);
 611         RCU_INIT_POINTER(nat_rtp_rtcp_hook, NULL);
 612         RCU_INIT_POINTER(nat_t120_hook, NULL);
 613         RCU_INIT_POINTER(nat_h245_hook, NULL);
 614         RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
 615         RCU_INIT_POINTER(nat_q931_hook, NULL);
 616         nf_ct_helper_expectfn_unregister(&q931_nat);
 617         nf_ct_helper_expectfn_unregister(&callforwarding_nat);
 618         synchronize_rcu();
 619 }
 620
 621 /****************************************************************************/
 622 module_init(init);
 623 module_exit(fini);
 624
 625 MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
 626 MODULE_DESCRIPTION("H.323 NAT helper");
 627 MODULE_LICENSE("GPL");
 628 MODULE_ALIAS("ip_nat_h323");