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  *
   6  * This source code is licensed under General Public License version 2.
   7  *
   8  * Based on the 'brute force' H.323 NAT module by
   9  * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/tcp.h>
  14 #include <net/tcp.h>
  15
  16 #include <net/netfilter/nf_nat.h>
  17 #include <net/netfilter/nf_nat_helper.h>
  18 #include <net/netfilter/nf_nat_rule.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,
  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                                               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                                               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,
  73                          unsigned char **data, int dataoff,
  74                          TransportAddress *taddr,
  75                          union nf_inet_addr *addr, __be16 port)
  76 {
  77         return set_addr(skb, data, dataoff, taddr->ipAddress.ip,
  78                         addr->ip, port);
  79 }
  80
  81 /****************************************************************************/
  82 static int set_h245_addr(struct sk_buff *skb,
  83                          unsigned char **data, int dataoff,
  84                          H245_TransportAddress *taddr,
  85                          union nf_inet_addr *addr, __be16 port)
  86 {
  87         return set_addr(skb, 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 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, data, 0, &taddr[i],
 122                                                      &ct->tuplehash[!dir].
 123                                                      tuple.dst.u3,
 124                                                      info->sig_port[!dir]);
 125                         } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
 126                                    port == info->sig_port[dir]) {
 127                                 /* GK->GW */
 128                                 pr_debug("nf_nat_ras: set signal address %pI4:%hu->%pI4:%hu\n",
 129                                          &addr.ip, port,
 130                                          &ct->tuplehash[!dir].tuple.src.u3.ip,
 131                                          info->sig_port[!dir]);
 132                                 return set_h225_addr(skb, data, 0, &taddr[i],
 133                                                      &ct->tuplehash[!dir].
 134                                                      tuple.src.u3,
 135                                                      info->sig_port[!dir]);
 136                         }
 137                 }
 138         }
 139
 140         return 0;
 141 }
 142
 143 /****************************************************************************/
 144 static int set_ras_addr(struct sk_buff *skb, struct nf_conn *ct,
 145                         enum ip_conntrack_info ctinfo,
 146                         unsigned char **data,
 147                         TransportAddress *taddr, int count)
 148 {
 149         int dir = CTINFO2DIR(ctinfo);
 150         int i;
 151         __be16 port;
 152         union nf_inet_addr addr;
 153
 154         for (i = 0; i < count; i++) {
 155                 if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
 156                     addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
 157                     port == ct->tuplehash[dir].tuple.src.u.udp.port) {
 158                         pr_debug("nf_nat_ras: set rasAddress %pI4:%hu->%pI4:%hu\n",
 159                                  &addr.ip, ntohs(port),
 160                                  &ct->tuplehash[!dir].tuple.dst.u3.ip,
 161                                  ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port));
 162                         return set_h225_addr(skb, data, 0, &taddr[i],
 163                                              &ct->tuplehash[!dir].tuple.dst.u3,
 164                                              ct->tuplehash[!dir].tuple.
 165                                                                 dst.u.udp.port);
 166                 }
 167         }
 168
 169         return 0;
 170 }
 171
 172 /****************************************************************************/
 173 static int nat_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
 174                         enum ip_conntrack_info ctinfo,
 175                         unsigned char **data, int dataoff,
 176                         H245_TransportAddress *taddr,
 177                         __be16 port, __be16 rtp_port,
 178                         struct nf_conntrack_expect *rtp_exp,
 179                         struct nf_conntrack_expect *rtcp_exp)
 180 {
 181         struct nf_ct_h323_master *info = nfct_help_data(ct);
 182         int dir = CTINFO2DIR(ctinfo);
 183         int i;
 184         u_int16_t nated_port;
 185
 186         /* Set expectations for NAT */
 187         rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
 188         rtp_exp->expectfn = nf_nat_follow_master;
 189         rtp_exp->dir = !dir;
 190         rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
 191         rtcp_exp->expectfn = nf_nat_follow_master;
 192         rtcp_exp->dir = !dir;
 193
 194         /* Lookup existing expects */
 195         for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
 196                 if (info->rtp_port[i][dir] == rtp_port) {
 197                         /* Expected */
 198
 199                         /* Use allocated ports first. This will refresh
 200                          * the expects */
 201                         rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
 202                         rtcp_exp->tuple.dst.u.udp.port =
 203                             htons(ntohs(info->rtp_port[i][dir]) + 1);
 204                         break;
 205                 } else if (info->rtp_port[i][dir] == 0) {
 206                         /* Not expected */
 207                         break;
 208                 }
 209         }
 210
 211         /* Run out of expectations */
 212         if (i >= H323_RTP_CHANNEL_MAX) {
 213                 net_notice_ratelimited("nf_nat_h323: out of expectations\n");
 214                 return 0;
 215         }
 216
 217         /* Try to get a pair of ports. */
 218         for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
 219              nated_port != 0; nated_port += 2) {
 220                 int ret;
 221
 222                 rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
 223                 ret = nf_ct_expect_related(rtp_exp);
 224                 if (ret == 0) {
 225                         rtcp_exp->tuple.dst.u.udp.port =
 226                             htons(nated_port + 1);
 227                         ret = nf_ct_expect_related(rtcp_exp);
 228                         if (ret == 0)
 229                                 break;
 230                         else if (ret != -EBUSY) {
 231                                 nf_ct_unexpect_related(rtp_exp);
 232                                 nated_port = 0;
 233                                 break;
 234                         }
 235                 } else if (ret != -EBUSY) {
 236                         nated_port = 0;
 237                         break;
 238                 }
 239         }
 240
 241         if (nated_port == 0) {  /* No port available */
 242                 net_notice_ratelimited("nf_nat_h323: out of RTP ports\n");
 243                 return 0;
 244         }
 245
 246         /* Modify signal */
 247         if (set_h245_addr(skb, data, dataoff, taddr,
 248                           &ct->tuplehash[!dir].tuple.dst.u3,
 249                           htons((port & htons(1)) ? nated_port + 1 :
 250                                                     nated_port)) == 0) {
 251                 /* Save ports */
 252                 info->rtp_port[i][dir] = rtp_port;
 253                 info->rtp_port[i][!dir] = htons(nated_port);
 254         } else {
 255                 nf_ct_unexpect_related(rtp_exp);
 256                 nf_ct_unexpect_related(rtcp_exp);
 257                 return -1;
 258         }
 259
 260         /* Success */
 261         pr_debug("nf_nat_h323: expect RTP %pI4:%hu->%pI4:%hu\n",
 262                  &rtp_exp->tuple.src.u3.ip,
 263                  ntohs(rtp_exp->tuple.src.u.udp.port),
 264                  &rtp_exp->tuple.dst.u3.ip,
 265                  ntohs(rtp_exp->tuple.dst.u.udp.port));
 266         pr_debug("nf_nat_h323: expect RTCP %pI4:%hu->%pI4:%hu\n",
 267                  &rtcp_exp->tuple.src.u3.ip,
 268                  ntohs(rtcp_exp->tuple.src.u.udp.port),
 269                  &rtcp_exp->tuple.dst.u3.ip,
 270                  ntohs(rtcp_exp->tuple.dst.u.udp.port));
 271
 272         return 0;
 273 }
 274
 275 /****************************************************************************/
 276 static int nat_t120(struct sk_buff *skb, struct nf_conn *ct,
 277                     enum ip_conntrack_info ctinfo,
 278                     unsigned char **data, int dataoff,
 279                     H245_TransportAddress *taddr, __be16 port,
 280                     struct nf_conntrack_expect *exp)
 281 {
 282         int dir = CTINFO2DIR(ctinfo);
 283         u_int16_t nated_port = ntohs(port);
 284
 285         /* Set expectations for NAT */
 286         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 287         exp->expectfn = nf_nat_follow_master;
 288         exp->dir = !dir;
 289
 290         /* Try to get same port: if not, try to change it. */
 291         for (; nated_port != 0; nated_port++) {
 292                 int ret;
 293
 294                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 295                 ret = nf_ct_expect_related(exp);
 296                 if (ret == 0)
 297                         break;
 298                 else if (ret != -EBUSY) {
 299                         nated_port = 0;
 300                         break;
 301                 }
 302         }
 303
 304         if (nated_port == 0) {  /* No port available */
 305                 net_notice_ratelimited("nf_nat_h323: out of TCP ports\n");
 306                 return 0;
 307         }
 308
 309         /* Modify signal */
 310         if (set_h245_addr(skb, data, dataoff, taddr,
 311                           &ct->tuplehash[!dir].tuple.dst.u3,
 312                           htons(nated_port)) < 0) {
 313                 nf_ct_unexpect_related(exp);
 314                 return -1;
 315         }
 316
 317         pr_debug("nf_nat_h323: expect T.120 %pI4:%hu->%pI4:%hu\n",
 318                  &exp->tuple.src.u3.ip,
 319                  ntohs(exp->tuple.src.u.tcp.port),
 320                  &exp->tuple.dst.u3.ip,
 321                  ntohs(exp->tuple.dst.u.tcp.port));
 322
 323         return 0;
 324 }
 325
 326 /****************************************************************************/
 327 static int nat_h245(struct sk_buff *skb, struct nf_conn *ct,
 328                     enum ip_conntrack_info ctinfo,
 329                     unsigned char **data, int dataoff,
 330                     TransportAddress *taddr, __be16 port,
 331                     struct nf_conntrack_expect *exp)
 332 {
 333         struct nf_ct_h323_master *info = nfct_help_data(ct);
 334         int dir = CTINFO2DIR(ctinfo);
 335         u_int16_t nated_port = ntohs(port);
 336
 337         /* Set expectations for NAT */
 338         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 339         exp->expectfn = nf_nat_follow_master;
 340         exp->dir = !dir;
 341
 342         /* Check existing expects */
 343         if (info->sig_port[dir] == port)
 344                 nated_port = ntohs(info->sig_port[!dir]);
 345
 346         /* Try to get same port: if not, try to change it. */
 347         for (; nated_port != 0; nated_port++) {
 348                 int ret;
 349
 350                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 351                 ret = nf_ct_expect_related(exp);
 352                 if (ret == 0)
 353                         break;
 354                 else if (ret != -EBUSY) {
 355                         nated_port = 0;
 356                         break;
 357                 }
 358         }
 359
 360         if (nated_port == 0) {  /* No port available */
 361                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 362                 return 0;
 363         }
 364
 365         /* Modify signal */
 366         if (set_h225_addr(skb, data, dataoff, taddr,
 367                           &ct->tuplehash[!dir].tuple.dst.u3,
 368                           htons(nated_port)) == 0) {
 369                 /* Save ports */
 370                 info->sig_port[dir] = port;
 371                 info->sig_port[!dir] = htons(nated_port);
 372         } else {
 373                 nf_ct_unexpect_related(exp);
 374                 return -1;
 375         }
 376
 377         pr_debug("nf_nat_q931: expect H.245 %pI4:%hu->%pI4:%hu\n",
 378                  &exp->tuple.src.u3.ip,
 379                  ntohs(exp->tuple.src.u.tcp.port),
 380                  &exp->tuple.dst.u3.ip,
 381                  ntohs(exp->tuple.dst.u.tcp.port));
 382
 383         return 0;
 384 }
 385
 386 /****************************************************************************
 387  * This conntrack expect function replaces nf_conntrack_q931_expect()
 388  * which was set by nf_conntrack_h323.c.
 389  ****************************************************************************/
 390 static void ip_nat_q931_expect(struct nf_conn *new,
 391                                struct nf_conntrack_expect *this)
 392 {
 393         struct nf_nat_ipv4_range range;
 394
 395         if (this->tuple.src.u3.ip != 0) {       /* Only accept calls from GK */
 396                 nf_nat_follow_master(new, this);
 397                 return;
 398         }
 399
 400         /* This must be a fresh one. */
 401         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 402
 403         /* Change src to where master sends to */
 404         range.flags = NF_NAT_RANGE_MAP_IPS;
 405         range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
 406         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 407
 408         /* For DST manip, map port here to where it's expected. */
 409         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 410         range.min = range.max = this->saved_proto;
 411         range.min_ip = range.max_ip =
 412             new->master->tuplehash[!this->dir].tuple.src.u3.ip;
 413         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 414 }
 415
 416 /****************************************************************************/
 417 static int nat_q931(struct sk_buff *skb, struct nf_conn *ct,
 418                     enum ip_conntrack_info ctinfo,
 419                     unsigned char **data, TransportAddress *taddr, int idx,
 420                     __be16 port, struct nf_conntrack_expect *exp)
 421 {
 422         struct nf_ct_h323_master *info = nfct_help_data(ct);
 423         int dir = CTINFO2DIR(ctinfo);
 424         u_int16_t nated_port = ntohs(port);
 425         union nf_inet_addr addr;
 426
 427         /* Set expectations for NAT */
 428         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 429         exp->expectfn = ip_nat_q931_expect;
 430         exp->dir = !dir;
 431
 432         /* Check existing expects */
 433         if (info->sig_port[dir] == port)
 434                 nated_port = ntohs(info->sig_port[!dir]);
 435
 436         /* Try to get same port: if not, try to change it. */
 437         for (; nated_port != 0; nated_port++) {
 438                 int ret;
 439
 440                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 441                 ret = nf_ct_expect_related(exp);
 442                 if (ret == 0)
 443                         break;
 444                 else if (ret != -EBUSY) {
 445                         nated_port = 0;
 446                         break;
 447                 }
 448         }
 449
 450         if (nated_port == 0) {  /* No port available */
 451                 net_notice_ratelimited("nf_nat_ras: out of TCP ports\n");
 452                 return 0;
 453         }
 454
 455         /* Modify signal */
 456         if (set_h225_addr(skb, data, 0, &taddr[idx],
 457                           &ct->tuplehash[!dir].tuple.dst.u3,
 458                           htons(nated_port)) == 0) {
 459                 /* Save ports */
 460                 info->sig_port[dir] = port;
 461                 info->sig_port[!dir] = htons(nated_port);
 462
 463                 /* Fix for Gnomemeeting */
 464                 if (idx > 0 &&
 465                     get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
 466                     (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
 467                         set_h225_addr(skb, data, 0, &taddr[0],
 468                                       &ct->tuplehash[!dir].tuple.dst.u3,
 469                                       info->sig_port[!dir]);
 470                 }
 471         } else {
 472                 nf_ct_unexpect_related(exp);
 473                 return -1;
 474         }
 475
 476         /* Success */
 477         pr_debug("nf_nat_ras: expect Q.931 %pI4:%hu->%pI4:%hu\n",
 478                  &exp->tuple.src.u3.ip,
 479                  ntohs(exp->tuple.src.u.tcp.port),
 480                  &exp->tuple.dst.u3.ip,
 481                  ntohs(exp->tuple.dst.u.tcp.port));
 482
 483         return 0;
 484 }
 485
 486 /****************************************************************************/
 487 static void ip_nat_callforwarding_expect(struct nf_conn *new,
 488                                          struct nf_conntrack_expect *this)
 489 {
 490         struct nf_nat_ipv4_range range;
 491
 492         /* This must be a fresh one. */
 493         BUG_ON(new->status & IPS_NAT_DONE_MASK);
 494
 495         /* Change src to where master sends to */
 496         range.flags = NF_NAT_RANGE_MAP_IPS;
 497         range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
 498         nf_nat_setup_info(new, &range, NF_NAT_MANIP_SRC);
 499
 500         /* For DST manip, map port here to where it's expected. */
 501         range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
 502         range.min = range.max = this->saved_proto;
 503         range.min_ip = range.max_ip = this->saved_ip;
 504         nf_nat_setup_info(new, &range, NF_NAT_MANIP_DST);
 505 }
 506
 507 /****************************************************************************/
 508 static int nat_callforwarding(struct sk_buff *skb, struct nf_conn *ct,
 509                               enum ip_conntrack_info ctinfo,
 510                               unsigned char **data, int dataoff,
 511                               TransportAddress *taddr, __be16 port,
 512                               struct nf_conntrack_expect *exp)
 513 {
 514         int dir = CTINFO2DIR(ctinfo);
 515         u_int16_t nated_port;
 516
 517         /* Set expectations for NAT */
 518         exp->saved_ip = exp->tuple.dst.u3.ip;
 519         exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
 520         exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
 521         exp->expectfn = ip_nat_callforwarding_expect;
 522         exp->dir = !dir;
 523
 524         /* Try to get same port: if not, try to change it. */
 525         for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
 526                 int ret;
 527
 528                 exp->tuple.dst.u.tcp.port = htons(nated_port);
 529                 ret = nf_ct_expect_related(exp);
 530                 if (ret == 0)
 531                         break;
 532                 else if (ret != -EBUSY) {
 533                         nated_port = 0;
 534                         break;
 535                 }
 536         }
 537
 538         if (nated_port == 0) {  /* No port available */
 539                 net_notice_ratelimited("nf_nat_q931: out of TCP ports\n");
 540                 return 0;
 541         }
 542
 543         /* Modify signal */
 544         if (!set_h225_addr(skb, data, dataoff, taddr,
 545                            &ct->tuplehash[!dir].tuple.dst.u3,
 546                            htons(nated_port)) == 0) {
 547                 nf_ct_unexpect_related(exp);
 548                 return -1;
 549         }
 550
 551         /* Success */
 552         pr_debug("nf_nat_q931: expect Call Forwarding %pI4:%hu->%pI4:%hu\n",
 553                  &exp->tuple.src.u3.ip,
 554                  ntohs(exp->tuple.src.u.tcp.port),
 555                  &exp->tuple.dst.u3.ip,
 556                  ntohs(exp->tuple.dst.u.tcp.port));
 557
 558         return 0;
 559 }
 560
 561 static struct nf_ct_helper_expectfn q931_nat = {
 562         .name           = "Q.931",
 563         .expectfn       = ip_nat_q931_expect,
 564 };
 565
 566 static struct nf_ct_helper_expectfn callforwarding_nat = {
 567         .name           = "callforwarding",
 568         .expectfn       = ip_nat_callforwarding_expect,
 569 };
 570
 571 /****************************************************************************/
 572 static int __init init(void)
 573 {
 574         BUG_ON(set_h245_addr_hook != NULL);
 575         BUG_ON(set_h225_addr_hook != NULL);
 576         BUG_ON(set_sig_addr_hook != NULL);
 577         BUG_ON(set_ras_addr_hook != NULL);
 578         BUG_ON(nat_rtp_rtcp_hook != NULL);
 579         BUG_ON(nat_t120_hook != NULL);
 580         BUG_ON(nat_h245_hook != NULL);
 581         BUG_ON(nat_callforwarding_hook != NULL);
 582         BUG_ON(nat_q931_hook != NULL);
 583
 584         RCU_INIT_POINTER(set_h245_addr_hook, set_h245_addr);
 585         RCU_INIT_POINTER(set_h225_addr_hook, set_h225_addr);
 586         RCU_INIT_POINTER(set_sig_addr_hook, set_sig_addr);
 587         RCU_INIT_POINTER(set_ras_addr_hook, set_ras_addr);
 588         RCU_INIT_POINTER(nat_rtp_rtcp_hook, nat_rtp_rtcp);
 589         RCU_INIT_POINTER(nat_t120_hook, nat_t120);
 590         RCU_INIT_POINTER(nat_h245_hook, nat_h245);
 591         RCU_INIT_POINTER(nat_callforwarding_hook, nat_callforwarding);
 592         RCU_INIT_POINTER(nat_q931_hook, nat_q931);
 593         nf_ct_helper_expectfn_register(&q931_nat);
 594         nf_ct_helper_expectfn_register(&callforwarding_nat);
 595         return 0;
 596 }
 597
 598 /****************************************************************************/
 599 static void __exit fini(void)
 600 {
 601         RCU_INIT_POINTER(set_h245_addr_hook, NULL);
 602         RCU_INIT_POINTER(set_h225_addr_hook, NULL);
 603         RCU_INIT_POINTER(set_sig_addr_hook, NULL);
 604         RCU_INIT_POINTER(set_ras_addr_hook, NULL);
 605         RCU_INIT_POINTER(nat_rtp_rtcp_hook, NULL);
 606         RCU_INIT_POINTER(nat_t120_hook, NULL);
 607         RCU_INIT_POINTER(nat_h245_hook, NULL);
 608         RCU_INIT_POINTER(nat_callforwarding_hook, NULL);
 609         RCU_INIT_POINTER(nat_q931_hook, NULL);
 610         nf_ct_helper_expectfn_unregister(&q931_nat);
 611         nf_ct_helper_expectfn_unregister(&callforwarding_nat);
 612         synchronize_rcu();
 613 }
 614
 615 /****************************************************************************/
 616 module_init(init);
 617 module_exit(fini);
 618
 619 MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
 620 MODULE_DESCRIPTION("H.323 NAT helper");
 621 MODULE_LICENSE("GPL");
 622 MODULE_ALIAS("ip_nat_h323");