This commit was manufactured by cvs2svn to create branch 'vserver'.
[linux-2.6.git] / net / ipv4 / netfilter / nf_nat_h323.c
diff --git a/net/ipv4/netfilter/nf_nat_h323.c b/net/ipv4/netfilter/nf_nat_h323.c
new file mode 100644 (file)
index 0000000..fb9ab01
--- /dev/null
@@ -0,0 +1,596 @@
+/*
+ * H.323 extension for NAT alteration.
+ *
+ * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
+ *
+ * This source code is licensed under General Public License version 2.
+ *
+ * Based on the 'brute force' H.323 NAT module by
+ * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/tcp.h>
+#include <net/tcp.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_h323.h>
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/****************************************************************************/
+static int set_addr(struct sk_buff **pskb,
+                   unsigned char **data, int dataoff,
+                   unsigned int addroff, __be32 ip, __be16 port)
+{
+       enum ip_conntrack_info ctinfo;
+       struct nf_conn *ct = ip_conntrack_get(*pskb, &ctinfo);
+       struct {
+               __be32 ip;
+               __be16 port;
+       } __attribute__ ((__packed__)) buf;
+       struct tcphdr _tcph, *th;
+
+       buf.ip = ip;
+       buf.port = port;
+       addroff += dataoff;
+
+       if ((*pskb)->nh.iph->protocol == IPPROTO_TCP) {
+               if (!nf_nat_mangle_tcp_packet(pskb, ct, ctinfo,
+                                             addroff, sizeof(buf),
+                                             (char *) &buf, sizeof(buf))) {
+                       if (net_ratelimit())
+                               printk("nf_nat_h323: nf_nat_mangle_tcp_packet"
+                                      " error\n");
+                       return -1;
+               }
+
+               /* Relocate data pointer */
+               th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl * 4,
+                                       sizeof(_tcph), &_tcph);
+               if (th == NULL)
+                       return -1;
+               *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+                   th->doff * 4 + dataoff;
+       } else {
+               if (!nf_nat_mangle_udp_packet(pskb, ct, ctinfo,
+                                             addroff, sizeof(buf),
+                                             (char *) &buf, sizeof(buf))) {
+                       if (net_ratelimit())
+                               printk("nf_nat_h323: nf_nat_mangle_udp_packet"
+                                      " error\n");
+                       return -1;
+               }
+               /* nf_nat_mangle_udp_packet uses skb_make_writable() to copy
+                * or pull everything in a linear buffer, so we can safely
+                * use the skb pointers now */
+               *data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
+                   sizeof(struct udphdr);
+       }
+
+       return 0;
+}
+
+/****************************************************************************/
+static int set_h225_addr(struct sk_buff **pskb,
+                        unsigned char **data, int dataoff,
+                        TransportAddress *taddr,
+                        union nf_conntrack_address *addr, __be16 port)
+{
+       return set_addr(pskb, data, dataoff, taddr->ipAddress.ip,
+                       addr->ip, port);
+}
+
+/****************************************************************************/
+static int set_h245_addr(struct sk_buff **pskb,
+                        unsigned char **data, int dataoff,
+                        H245_TransportAddress *taddr,
+                        union nf_conntrack_address *addr, __be16 port)
+{
+       return set_addr(pskb, data, dataoff,
+                       taddr->unicastAddress.iPAddress.network,
+                       addr->ip, port);
+}
+
+/****************************************************************************/
+static int set_sig_addr(struct sk_buff **pskb, struct nf_conn *ct,
+                       enum ip_conntrack_info ctinfo,
+                       unsigned char **data,
+                       TransportAddress *taddr, int count)
+{
+       struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+       int dir = CTINFO2DIR(ctinfo);
+       int i;
+       __be16 port;
+       union nf_conntrack_address addr;
+
+       for (i = 0; i < count; i++) {
+               if (get_h225_addr(ct, *data, &taddr[i], &addr, &port)) {
+                       if (addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
+                           port == info->sig_port[dir]) {
+                               /* GW->GK */
+
+                               /* Fix for Gnomemeeting */
+                               if (i > 0 &&
+                                   get_h225_addr(ct, *data, &taddr[0],
+                                                 &addr, &port) &&
+                                   (ntohl(addr.ip) & 0xff000000) == 0x7f000000)
+                                       i = 0;
+
+                               DEBUGP
+                                   ("nf_nat_ras: set signal address "
+                                    "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+                                    NIPQUAD(ip), port,
+                                    NIPQUAD(ct->tuplehash[!dir].tuple.dst.
+                                            ip), info->sig_port[!dir]);
+                               return set_h225_addr(pskb, data, 0, &taddr[i],
+                                                    &ct->tuplehash[!dir].
+                                                    tuple.dst.u3,
+                                                    info->sig_port[!dir]);
+                       } else if (addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
+                                  port == info->sig_port[dir]) {
+                               /* GK->GW */
+                               DEBUGP
+                                   ("nf_nat_ras: set signal address "
+                                    "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+                                    NIPQUAD(ip), port,
+                                    NIPQUAD(ct->tuplehash[!dir].tuple.src.
+                                            ip), info->sig_port[!dir]);
+                               return set_h225_addr(pskb, data, 0, &taddr[i],
+                                                    &ct->tuplehash[!dir].
+                                                    tuple.src.u3,
+                                                    info->sig_port[!dir]);
+                       }
+               }
+       }
+
+       return 0;
+}
+
+/****************************************************************************/
+static int set_ras_addr(struct sk_buff **pskb, struct nf_conn *ct,
+                       enum ip_conntrack_info ctinfo,
+                       unsigned char **data,
+                       TransportAddress *taddr, int count)
+{
+       int dir = CTINFO2DIR(ctinfo);
+       int i;
+       __be16 port;
+       union nf_conntrack_address addr;
+
+       for (i = 0; i < count; i++) {
+               if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
+                   addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
+                   port == ct->tuplehash[dir].tuple.src.u.udp.port) {
+                       DEBUGP("nf_nat_ras: set rasAddress "
+                              "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+                              NIPQUAD(ip), ntohs(port),
+                              NIPQUAD(ct->tuplehash[!dir].tuple.dst.u3.ip),
+                              ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.
+                                    port));
+                       return set_h225_addr(pskb, data, 0, &taddr[i],
+                                            &ct->tuplehash[!dir].tuple.dst.u3,
+                                            ct->tuplehash[!dir].tuple.
+                                                               dst.u.udp.port);
+               }
+       }
+
+       return 0;
+}
+
+/****************************************************************************/
+static int nat_rtp_rtcp(struct sk_buff **pskb, struct nf_conn *ct,
+                       enum ip_conntrack_info ctinfo,
+                       unsigned char **data, int dataoff,
+                       H245_TransportAddress *taddr,
+                       __be16 port, __be16 rtp_port,
+                       struct nf_conntrack_expect *rtp_exp,
+                       struct nf_conntrack_expect *rtcp_exp)
+{
+       struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+       int dir = CTINFO2DIR(ctinfo);
+       int i;
+       u_int16_t nated_port;
+
+       /* Set expectations for NAT */
+       rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
+       rtp_exp->expectfn = nf_nat_follow_master;
+       rtp_exp->dir = !dir;
+       rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
+       rtcp_exp->expectfn = nf_nat_follow_master;
+       rtcp_exp->dir = !dir;
+
+       /* Lookup existing expects */
+       for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
+               if (info->rtp_port[i][dir] == rtp_port) {
+                       /* Expected */
+
+                       /* Use allocated ports first. This will refresh
+                        * the expects */
+                       rtp_exp->tuple.dst.u.udp.port = info->rtp_port[i][dir];
+                       rtcp_exp->tuple.dst.u.udp.port =
+                           htons(ntohs(info->rtp_port[i][dir]) + 1);
+                       break;
+               } else if (info->rtp_port[i][dir] == 0) {
+                       /* Not expected */
+                       break;
+               }
+       }
+
+       /* Run out of expectations */
+       if (i >= H323_RTP_CHANNEL_MAX) {
+               if (net_ratelimit())
+                       printk("nf_nat_h323: out of expectations\n");
+               return 0;
+       }
+
+       /* Try to get a pair of ports. */
+       for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
+            nated_port != 0; nated_port += 2) {
+               rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
+               if (nf_conntrack_expect_related(rtp_exp) == 0) {
+                       rtcp_exp->tuple.dst.u.udp.port =
+                           htons(nated_port + 1);
+                       if (nf_conntrack_expect_related(rtcp_exp) == 0)
+                               break;
+                       nf_conntrack_unexpect_related(rtp_exp);
+               }
+       }
+
+       if (nated_port == 0) {  /* No port available */
+               if (net_ratelimit())
+                       printk("nf_nat_h323: out of RTP ports\n");
+               return 0;
+       }
+
+       /* Modify signal */
+       if (set_h245_addr(pskb, data, dataoff, taddr,
+                         &ct->tuplehash[!dir].tuple.dst.u3,
+                         htons((port & htons(1)) ? nated_port + 1 :
+                                                   nated_port)) == 0) {
+               /* Save ports */
+               info->rtp_port[i][dir] = rtp_port;
+               info->rtp_port[i][!dir] = htons(nated_port);
+       } else {
+               nf_conntrack_unexpect_related(rtp_exp);
+               nf_conntrack_unexpect_related(rtcp_exp);
+               return -1;
+       }
+
+       /* Success */
+       DEBUGP("nf_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(rtp_exp->tuple.src.ip),
+              ntohs(rtp_exp->tuple.src.u.udp.port),
+              NIPQUAD(rtp_exp->tuple.dst.ip),
+              ntohs(rtp_exp->tuple.dst.u.udp.port));
+       DEBUGP("nf_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(rtcp_exp->tuple.src.ip),
+              ntohs(rtcp_exp->tuple.src.u.udp.port),
+              NIPQUAD(rtcp_exp->tuple.dst.ip),
+              ntohs(rtcp_exp->tuple.dst.u.udp.port));
+
+       return 0;
+}
+
+/****************************************************************************/
+static int nat_t120(struct sk_buff **pskb, struct nf_conn *ct,
+                   enum ip_conntrack_info ctinfo,
+                   unsigned char **data, int dataoff,
+                   H245_TransportAddress *taddr, __be16 port,
+                   struct nf_conntrack_expect *exp)
+{
+       int dir = CTINFO2DIR(ctinfo);
+       u_int16_t nated_port = ntohs(port);
+
+       /* Set expectations for NAT */
+       exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+       exp->expectfn = nf_nat_follow_master;
+       exp->dir = !dir;
+
+       /* Try to get same port: if not, try to change it. */
+       for (; nated_port != 0; nated_port++) {
+               exp->tuple.dst.u.tcp.port = htons(nated_port);
+               if (nf_conntrack_expect_related(exp) == 0)
+                       break;
+       }
+
+       if (nated_port == 0) {  /* No port available */
+               if (net_ratelimit())
+                       printk("nf_nat_h323: out of TCP ports\n");
+               return 0;
+       }
+
+       /* Modify signal */
+       if (set_h245_addr(pskb, data, dataoff, taddr,
+                         &ct->tuplehash[!dir].tuple.dst.u3,
+                         htons(nated_port)) < 0) {
+               nf_conntrack_unexpect_related(exp);
+               return -1;
+       }
+
+       DEBUGP("nf_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+              NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+       return 0;
+}
+
+/****************************************************************************/
+static int nat_h245(struct sk_buff **pskb, struct nf_conn *ct,
+                   enum ip_conntrack_info ctinfo,
+                   unsigned char **data, int dataoff,
+                   TransportAddress *taddr, __be16 port,
+                   struct nf_conntrack_expect *exp)
+{
+       struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+       int dir = CTINFO2DIR(ctinfo);
+       u_int16_t nated_port = ntohs(port);
+
+       /* Set expectations for NAT */
+       exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+       exp->expectfn = nf_nat_follow_master;
+       exp->dir = !dir;
+
+       /* Check existing expects */
+       if (info->sig_port[dir] == port)
+               nated_port = ntohs(info->sig_port[!dir]);
+
+       /* Try to get same port: if not, try to change it. */
+       for (; nated_port != 0; nated_port++) {
+               exp->tuple.dst.u.tcp.port = htons(nated_port);
+               if (nf_conntrack_expect_related(exp) == 0)
+                       break;
+       }
+
+       if (nated_port == 0) {  /* No port available */
+               if (net_ratelimit())
+                       printk("nf_nat_q931: out of TCP ports\n");
+               return 0;
+       }
+
+       /* Modify signal */
+       if (set_h225_addr(pskb, data, dataoff, taddr,
+                         &ct->tuplehash[!dir].tuple.dst.u3,
+                         htons(nated_port)) == 0) {
+               /* Save ports */
+               info->sig_port[dir] = port;
+               info->sig_port[!dir] = htons(nated_port);
+       } else {
+               nf_conntrack_unexpect_related(exp);
+               return -1;
+       }
+
+       DEBUGP("nf_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+              NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+       return 0;
+}
+
+/****************************************************************************
+ * This conntrack expect function replaces nf_conntrack_q931_expect()
+ * which was set by nf_conntrack_h323.c.
+ ****************************************************************************/
+static void ip_nat_q931_expect(struct nf_conn *new,
+                              struct nf_conntrack_expect *this)
+{
+       struct ip_nat_range range;
+
+       if (this->tuple.src.u3.ip != 0) {       /* Only accept calls from GK */
+               nf_nat_follow_master(new, this);
+               return;
+       }
+
+       /* This must be a fresh one. */
+       BUG_ON(new->status & IPS_NAT_DONE_MASK);
+
+       /* Change src to where master sends to */
+       range.flags = IP_NAT_RANGE_MAP_IPS;
+       range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
+
+       /* hook doesn't matter, but it has to do source manip */
+       nf_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
+
+       /* For DST manip, map port here to where it's expected. */
+       range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+       range.min = range.max = this->saved_proto;
+       range.min_ip = range.max_ip =
+           new->master->tuplehash[!this->dir].tuple.src.u3.ip;
+
+       /* hook doesn't matter, but it has to do destination manip */
+       nf_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
+}
+
+/****************************************************************************/
+static int nat_q931(struct sk_buff **pskb, struct nf_conn *ct,
+                   enum ip_conntrack_info ctinfo,
+                   unsigned char **data, TransportAddress *taddr, int idx,
+                   __be16 port, struct nf_conntrack_expect *exp)
+{
+       struct nf_ct_h323_master *info = &nfct_help(ct)->help.ct_h323_info;
+       int dir = CTINFO2DIR(ctinfo);
+       u_int16_t nated_port = ntohs(port);
+       union nf_conntrack_address addr;
+
+       /* Set expectations for NAT */
+       exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+       exp->expectfn = ip_nat_q931_expect;
+       exp->dir = !dir;
+
+       /* Check existing expects */
+       if (info->sig_port[dir] == port)
+               nated_port = ntohs(info->sig_port[!dir]);
+
+       /* Try to get same port: if not, try to change it. */
+       for (; nated_port != 0; nated_port++) {
+               exp->tuple.dst.u.tcp.port = htons(nated_port);
+               if (nf_conntrack_expect_related(exp) == 0)
+                       break;
+       }
+
+       if (nated_port == 0) {  /* No port available */
+               if (net_ratelimit())
+                       printk("nf_nat_ras: out of TCP ports\n");
+               return 0;
+       }
+
+       /* Modify signal */
+       if (set_h225_addr(pskb, data, 0, &taddr[idx],
+                         &ct->tuplehash[!dir].tuple.dst.u3,
+                         htons(nated_port)) == 0) {
+               /* Save ports */
+               info->sig_port[dir] = port;
+               info->sig_port[!dir] = htons(nated_port);
+
+               /* Fix for Gnomemeeting */
+               if (idx > 0 &&
+                   get_h225_addr(ct, *data, &taddr[0], &addr, &port) &&
+                   (ntohl(addr.ip) & 0xff000000) == 0x7f000000) {
+                       set_h225_addr_hook(pskb, data, 0, &taddr[0],
+                                          &ct->tuplehash[!dir].tuple.dst.u3,
+                                          info->sig_port[!dir]);
+               }
+       } else {
+               nf_conntrack_unexpect_related(exp);
+               return -1;
+       }
+
+       /* Success */
+       DEBUGP("nf_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+              NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+       return 0;
+}
+
+/****************************************************************************/
+static void ip_nat_callforwarding_expect(struct nf_conn *new,
+                                        struct nf_conntrack_expect *this)
+{
+       struct nf_nat_range range;
+
+       /* This must be a fresh one. */
+       BUG_ON(new->status & IPS_NAT_DONE_MASK);
+
+       /* Change src to where master sends to */
+       range.flags = IP_NAT_RANGE_MAP_IPS;
+       range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.u3.ip;
+
+       /* hook doesn't matter, but it has to do source manip */
+       nf_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
+
+       /* For DST manip, map port here to where it's expected. */
+       range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
+       range.min = range.max = this->saved_proto;
+       range.min_ip = range.max_ip = this->saved_ip;
+
+       /* hook doesn't matter, but it has to do destination manip */
+       nf_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
+}
+
+/****************************************************************************/
+static int nat_callforwarding(struct sk_buff **pskb, struct nf_conn *ct,
+                             enum ip_conntrack_info ctinfo,
+                             unsigned char **data, int dataoff,
+                             TransportAddress *taddr, __be16 port,
+                             struct nf_conntrack_expect *exp)
+{
+       int dir = CTINFO2DIR(ctinfo);
+       u_int16_t nated_port;
+
+       /* Set expectations for NAT */
+       exp->saved_ip = exp->tuple.dst.u3.ip;
+       exp->tuple.dst.u3.ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
+       exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+       exp->expectfn = ip_nat_callforwarding_expect;
+       exp->dir = !dir;
+
+       /* Try to get same port: if not, try to change it. */
+       for (nated_port = ntohs(port); nated_port != 0; nated_port++) {
+               exp->tuple.dst.u.tcp.port = htons(nated_port);
+               if (nf_conntrack_expect_related(exp) == 0)
+                       break;
+       }
+
+       if (nated_port == 0) {  /* No port available */
+               if (net_ratelimit())
+                       printk("nf_nat_q931: out of TCP ports\n");
+               return 0;
+       }
+
+       /* Modify signal */
+       if (!set_h225_addr(pskb, data, dataoff, taddr,
+                          &ct->tuplehash[!dir].tuple.dst.u3,
+                          htons(nated_port)) == 0) {
+               nf_conntrack_unexpect_related(exp);
+               return -1;
+       }
+
+       /* Success */
+       DEBUGP("nf_nat_q931: expect Call Forwarding "
+              "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
+              NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
+              NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
+
+       return 0;
+}
+
+/****************************************************************************/
+static int __init init(void)
+{
+       BUG_ON(rcu_dereference(set_h245_addr_hook) != NULL);
+       BUG_ON(rcu_dereference(set_h225_addr_hook) != NULL);
+       BUG_ON(rcu_dereference(set_sig_addr_hook) != NULL);
+       BUG_ON(rcu_dereference(set_ras_addr_hook) != NULL);
+       BUG_ON(rcu_dereference(nat_rtp_rtcp_hook) != NULL);
+       BUG_ON(rcu_dereference(nat_t120_hook) != NULL);
+       BUG_ON(rcu_dereference(nat_h245_hook) != NULL);
+       BUG_ON(rcu_dereference(nat_callforwarding_hook) != NULL);
+       BUG_ON(rcu_dereference(nat_q931_hook) != NULL);
+
+       rcu_assign_pointer(set_h245_addr_hook, set_h245_addr);
+       rcu_assign_pointer(set_h225_addr_hook, set_h225_addr);
+       rcu_assign_pointer(set_sig_addr_hook, set_sig_addr);
+       rcu_assign_pointer(set_ras_addr_hook, set_ras_addr);
+       rcu_assign_pointer(nat_rtp_rtcp_hook, nat_rtp_rtcp);
+       rcu_assign_pointer(nat_t120_hook, nat_t120);
+       rcu_assign_pointer(nat_h245_hook, nat_h245);
+       rcu_assign_pointer(nat_callforwarding_hook, nat_callforwarding);
+       rcu_assign_pointer(nat_q931_hook, nat_q931);
+
+       DEBUGP("nf_nat_h323: init success\n");
+       return 0;
+}
+
+/****************************************************************************/
+static void __exit fini(void)
+{
+       rcu_assign_pointer(set_h245_addr_hook, NULL);
+       rcu_assign_pointer(set_h225_addr_hook, NULL);
+       rcu_assign_pointer(set_sig_addr_hook, NULL);
+       rcu_assign_pointer(set_ras_addr_hook, NULL);
+       rcu_assign_pointer(nat_rtp_rtcp_hook, NULL);
+       rcu_assign_pointer(nat_t120_hook, NULL);
+       rcu_assign_pointer(nat_h245_hook, NULL);
+       rcu_assign_pointer(nat_callforwarding_hook, NULL);
+       rcu_assign_pointer(nat_q931_hook, NULL);
+       synchronize_rcu();
+}
+
+/****************************************************************************/
+module_init(init);
+module_exit(fini);
+
+MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
+MODULE_DESCRIPTION("H.323 NAT helper");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ip_nat_h323");