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                                 continue;
 235                         } else if (ret < 0) {
 236                                 nf_ct_unexpect_related(rtp_exp);
 237                                 nated_port = 0;
 238                                 break;
 239                         }
 240                 } else if (ret != -EBUSY) {
 241                         nated_port = 0;
 242                         break;
 243                 }
 244         }
 245
 246         if (nated_port == 0) {  /* No port available */
 247                 net_notice_ratelimited("nf_nat_h323: out of RTP ports\n");
 248                 return 0;
 249         }
 250
 251         /* Modify signal */
 252         if (set_h245_addr(skb, protoff, data, dataoff, taddr,
 253                           &ct->tuplehash[!dir].tuple.dst.u3,
 254                           htons((port & htons(1)) ? nated_port + 1 :
 255                                                     nated_port))) {
 256                 nf_ct_unexpect_related(rtp_exp);
 257                 nf_ct_unexpect_related(rtcp_exp);
 258                 return -1;
 259         }
 260
 261         /* Save ports */
 262         info->rtp_port[i][dir] = rtp_port;
 263         info->rtp_port[i][!dir] = htons(nated_port);
 264
 265         /* Success */
 266         pr_debug("nf_nat_h323: expect RTP %pI4:%hu->%pI4:%hu\n",
 267                  &rtp_exp->tuple.src.u3.ip,
 268                  ntohs(rtp_exp->tuple.src.u.udp.port),
 269                  &rtp_exp->tuple.dst.u3.ip,
 270                  ntohs(rtp_exp->tuple.dst.u.udp.port));
 271         pr_debug("nf_nat_h323: expect RTCP %pI4:%hu->%pI4:%hu\n",
 272                  &rtcp_exp->tuple.src.u3.ip,
 273                  ntohs(rtcp_exp->tuple.src.u.udp.port),
 274                  &rtcp_exp->tuple.dst.u3.ip,
 275                  ntohs(rtcp_exp->tuple.dst.u.udp.port));
 276
 277         return 0;
 278 }
 279
 280 /****************************************************************************/
 281 static int nat_t120(struct sk_buff *skb, struct nf_conn *ct,
 282                     enum ip_conntrack_info ctinfo,
 283                     unsigned int protoff, unsigned char **data, int dataoff,
 284                     H245_TransportAddress *taddr, __be16 port,
 285                     struct nf_conntrack_expect *exp)
 286 {
 287         int dir = CTINFO2DIR(ctinfo);
 288         u_int16_t nated_port = ntohs(port);
 289
 290         /* Set expectations for NAT */
 291         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 292         exp->expectfn = nf_nat_follow_master;
 293         exp->dir = !dir;
 294
 295         /* Try to get same port: if not, try to change it. */
 296         for (; nated_port != 0; nated_port++) {
 297                 int ret;
 298
 299                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 300                 ret = nf_ct_expect_related(exp);
 301                 if (ret == 0)
 302                         break;
 303                 else if (ret != -EBUSY) {
 304                         nated_port = 0;
 305                         break;
 306                 }
 307         }
 308
 309         if (nated_port == 0) {  /* No port available */
 310                 net_notice_ratelimited("nf_nat_h323: out of TCP ports\n");
 311                 return 0;
 312         }
 313
 314         /* Modify signal */
 315         if (set_h245_addr(skb, protoff, data, dataoff, taddr,
 316                           &ct->tuplehash[!dir].tuple.dst.u3,
 317                           htons(nated_port)) < 0) {
 318                 nf_ct_unexpect_related(exp);
 319                 return -1;
 320         }
 321
 322         pr_debug("nf_nat_h323: expect T.120 %pI4:%hu->%pI4:%hu\n",
 323                  &exp->tuple.src.u3.ip,
 324                  ntohs(exp->tuple.src.u.tcp.port),
 325                  &exp->tuple.dst.u3.ip,
 326                  ntohs(exp->tuple.dst.u.tcp.port));
 327
 328         return 0;
 329 }
 330
 331 /****************************************************************************/
 332 static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
 333                     enum ip_conntrack_info ctinfo,
 334                     unsigned int protoff, unsigned char **data, int dataoff,
 335                     TransportAddress *taddr, __be16 port,
 336                     struct nf_conntrack_expect *exp)
 337 {
 338         struct nf_ct_h323_master *info = nfct_help_data(ct);
 339         int dir = CTINFO2DIR(ctinfo);
 340         u_int16_t nated_port = ntohs(port);
 341
 342         /* Set expectations for NAT */
 343         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 344         exp->expectfn = nf_nat_follow_master;
 345         exp->dir = !dir;
 346
 347         /* Check existing expects */
 348         if (info->sig_port[dir] == port)
 349                 nated_port = ntohs(info->sig_port[!dir]);
 350
 351         /* Try to get same port: if not, try to change it. */
 352         for (; nated_port != 0; nated_port++) {
 353                 int ret;
 354
 355                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 356                 ret = nf_ct_expect_related(exp);
 357                 if (ret == 0)
 358                         break;
 359                 else if (ret != -EBUSY) {
 360                         nated_port = 0;
 361                         break;
 362                 }
 363         }
 364
 365         if (nated_port == 0) {  /* No port available */
 366                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 367                 return 0;
 368         }
 369
 370         /* Modify signal */
 371         if (set_h225_addr(skb, protoff, data, dataoff, taddr,
 372                           &ct->tuplehash[!dir].tuple.dst.u3,
 373                           htons(nated_port))) {
 374                 nf_ct_unexpect_related(exp);
 375                 return -1;
 376         }
 377
 378         /* Save ports */
 379         info->sig_port[dir] = port;
 380         info->sig_port[!dir] = htons(nated_port);
 381
 382         pr_debug("nf_nat_q931: expect H.245 %pI4:%hu->%pI4:%hu\n",
 383                  &exp->tuple.src.u3.ip,
 384                  ntohs(exp->tuple.src.u.tcp.port),
 385                  &exp->tuple.dst.u3.ip,
 386                  ntohs(exp->tuple.dst.u.tcp.port));
 387
 388         return 0;
 389 }
 390
 391 /****************************************************************************
 392  * This conntrack expect function replaces nf_conntrack_q931_expect()
 393  * which was set by nf_conntrack_h323.c.
 394  ****************************************************************************/
 395 static void ip_nat_q931_expect(struct nf_conn *new,
 396                                struct nf_conntrack_expect *this)
 397 {
 398         struct nf_nat_range range;
 399
 400         if (this->tuple.src.u3.ip != 0) {       /* Only accept calls from GK */
 401                 nf_nat_follow_master(new, this);
 402                 return;
 403         }
 404
 405         /* This must be a fresh one. */
 406         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 407
 408         /* Change src to where master sends to */
 409         range.flags = NF_NAT_RANGE_MAP_IPS;
 410         range.min_addr = range.max_addr =
 411             new->tuplehash[!this->dir].tuple.src.u3;
 412         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 413
 414         /* For DST manip, map port here to where it's expected. */
 415         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 416         range.min_proto = range.max_proto = this->saved_proto;
 417         range.min_addr = range.max_addr =
 418             new->master->tuplehash[!this->dir].tuple.src.u3;
 419         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 420 }
 421
 422 /****************************************************************************/
 423 static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
 424                     enum ip_conntrack_info ctinfo,
 425                     unsigned int protoff, unsigned char **data,
 426                     TransportAddress *taddr, int idx,
 427                     __be16 port, struct nf_conntrack_expect *exp)
 428 {
 429         struct nf_ct_h323_master *info = nfct_help_data(ct);
 430         int dir = CTINFO2DIR(ctinfo);
 431         u_int16_t nated_port = ntohs(port);
 432         union nf_inet_addr addr;
 433
 434         /* Set expectations for NAT */
 435         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 436         exp->expectfn = ip_nat_q931_expect;
 437         exp->dir = !dir;
 438
 439         /* Check existing expects */
 440         if (info->sig_port[dir] == port)
 441                 nated_port = ntohs(info->sig_port[!dir]);
 442
 443         /* Try to get same port: if not, try to change it. */
 444         for (; nated_port != 0; nated_port++) {
 445                 int ret;
 446
 447                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 448                 ret = nf_ct_expect_related(exp);
 449                 if (ret == 0)
 450                         break;
 451                 else if (ret != -EBUSY) {
 452                         nated_port = 0;
 453                         break;
 454                 }
 455         }
 456
 457         if (nated_port == 0) {  /* No port available */
 458                 net_notice_ratelimited("nf_nat_ras: out of TCP ports\n");
 459                 return 0;
 460         }
 461
 462         /* Modify signal */
 463         if (set_h225_addr(skb, protoff, data, 0, &taddr[idx],
 464                           &ct->tuplehash[!dir].tuple.dst.u3,
 465                           htons(nated_port))) {
 466                 nf_ct_unexpect_related(exp);
 467                 return -1;
 468         }
 469
 470         /* Save ports */
 471         info->sig_port[dir] = port;
 472         info->sig_port[!dir] = htons(nated_port);
 473
 474         /* Fix for Gnomemeeting */
 475         if (idx > 0 &&
 476             get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
 477             (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
 478                 if (set_h225_addr(skb, protoff, data, 0, &taddr[0],
 479                                   &ct->tuplehash[!dir].tuple.dst.u3,
 480                                   info->sig_port[!dir])) {
 481                         nf_ct_unexpect_related(exp);
 482                         return -1;
 483                 }
 484         }
 485
 486         /* Success */
 487         pr_debug("nf_nat_ras: expect Q.931 %pI4:%hu->%pI4:%hu\n",
 488                  &exp->tuple.src.u3.ip,
 489                  ntohs(exp->tuple.src.u.tcp.port),
 490                  &exp->tuple.dst.u3.ip,
 491                  ntohs(exp->tuple.dst.u.tcp.port));
 492
 493         return 0;
 494 }
 495
 496 /****************************************************************************/
 497 static void ip_nat_callforwarding_expect(struct nf_conn *new,
 498                                          struct nf_conntrack_expect *this)
 499 {
 500         struct nf_nat_range range;
 501
 502         /* This must be a fresh one. */
 503         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 504
 505         /* Change src to where master sends to */
 506         range.flags = NF_NAT_RANGE_MAP_IPS;
 507         range.min_addr = range.max_addr =
 508             new->tuplehash[!this->dir].tuple.src.u3;
 509         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 510
 511         /* For DST manip, map port here to where it's expected. */
 512         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 513         range.min_proto = range.max_proto = this->saved_proto;
 514         range.min_addr = range.max_addr = this->saved_addr;
 515         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 516 }
 517
 518 /****************************************************************************/
 519 static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 520                               enum ip_conntrack_info ctinfo,
 521                               unsigned int protoff,
 522                               unsigned char **data, int dataoff,
 523                               TransportAddress *taddr, __be16 port,
 524                               struct nf_conntrack_expect *exp)
 525 {
 526         int dir = CTINFO2DIR(ctinfo);
 527         u_int16_t nated_port;
 528
 529         /* Set expectations for NAT */
 530         exp->saved_addr = exp->tuple.dst.u3;
 531         exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
 532         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 533         exp->expectfn = ip_nat_callforwarding_expect;
 534         exp->dir = !dir;
 535
 536         /* Try to get same port: if not, try to change it. */
 537         for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
 538                 int ret;
 539
 540                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 541                 ret = nf_ct_expect_related(exp);
 542                 if (ret == 0)
 543                         break;
 544                 else if (ret != -EBUSY) {
 545                         nated_port = 0;
 546                         break;
 547                 }
 548         }
 549
 550         if (nated_port == 0) {  /* No port available */
 551                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 552                 return 0;
 553         }
 554
 555         /* Modify signal */
 556         if (set_h225_addr(skb, protoff, data, dataoff, taddr,
 557                           &ct->tuplehash[!dir].tuple.dst.u3,
 558                           htons(nated_port))) {
 559                 nf_ct_unexpect_related(exp);
 560                 return -1;
 561         }
 562
 563         /* Success */
 564         pr_debug("nf_nat_q931: expect Call Forwarding %pI4:%hu->%pI4:%hu\n",
 565                  &exp->tuple.src.u3.ip,
 566                  ntohs(exp->tuple.src.u.tcp.port),
 567                  &exp->tuple.dst.u3.ip,
 568                  ntohs(exp->tuple.dst.u.tcp.port));
 569
 570         return 0;
 571 }
 572
 573 static struct nf_ct_helper_expectfn q931_nat = {
 574         .name           = "Q.931",
 575         .expectfn       = ip_nat_q931_expect,
 576 };
 577
 578 static struct nf_ct_helper_expectfn callforwarding_nat = {
 579         .name           = "callforwarding",
 580         .expectfn       = ip_nat_callforwarding_expect,
 581 };
 582
 583 /****************************************************************************/
 584 static int __init init(void)
 585 {
 586         BUG_ON(set_h245_addr_hook != NULL);
 587         BUG_ON(set_h225_addr_hook != NULL);
 588         BUG_ON(set_sig_addr_hook != NULL);
 589         BUG_ON(set_ras_addr_hook != NULL);
 590         BUG_ON(nat_rtp_rtcp_hook != NULL);
 591         BUG_ON(nat_t120_hook != NULL);
 592         BUG_ON(nat_h245_hook != NULL);
 593         BUG_ON(nat_callforwarding_hook != NULL);
 594         BUG_ON(nat_q931_hook != NULL);
 595
 596         RCU_INIT_POINTER(set_h245_addr_hook, set_h245_addr);
 597         RCU_INIT_POINTER(set_h225_addr_hook, set_h225_addr);
 598         RCU_INIT_POINTER(set_sig_addr_hook, set_sig_addr);
 599         RCU_INIT_POINTER(set_ras_addr_hook, set_ras_addr);
 600         RCU_INIT_POINTER(nat_rtp_rtcp_hook, nat_rtp_rtcp);
 601         RCU_INIT_POINTER(nat_t120_hook, nat_t120);
 602         RCU_INIT_POINTER(nat_h245_hook, nat_h245);
 603         RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
 604         RCU_INIT_POINTER(nat_q931_hook, nat_q931);
 605         nf_ct_helper_expectfn_register(&q931_nat);
 606         nf_ct_helper_expectfn_register(&callforwarding_nat);
 607         return 0;
 608 }
 609
 610 /****************************************************************************/
 611 static void __exit fini(void)
 612 {
 613         RCU_INIT_POINTER(set_h245_addr_hook, NULL);
 614         RCU_INIT_POINTER(set_h225_addr_hook, NULL);
 615         RCU_INIT_POINTER(set_sig_addr_hook, NULL);
 616         RCU_INIT_POINTER(set_ras_addr_hook, NULL);
 617         RCU_INIT_POINTER(nat_rtp_rtcp_hook, NULL);
 618         RCU_INIT_POINTER(nat_t120_hook, NULL);
 619         RCU_INIT_POINTER(nat_h245_hook, NULL);
 620         RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
 621         RCU_INIT_POINTER(nat_q931_hook, NULL);
 622         nf_ct_helper_expectfn_unregister(&q931_nat);
 623         nf_ct_helper_expectfn_unregister(&callforwarding_nat);
 624         synchronize_rcu();
 625 }
 626
 627 /****************************************************************************/
 628 module_init(init);
 629 module_exit(fini);
 630
 631 MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
 632 MODULE_DESCRIPTION("H.323 NAT helper");
 633 MODULE_LICENSE("GPL");
 634 MODULE_ALIAS("ip_nat_h323");