net/netfilter/nf_conntrack_h323_main.c

/*
 * H.323 connection tracking helper
 *
 * Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
 * Copyright (c) 2006-2012 Patrick McHardy <kaber@trash.net>
 *
 * This source code is licensed under General Public License version 2.
 *
 * Based on the 'brute force' H.323 connection tracking module by
 * Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
 *
 * For more information, please see http://nath323.sourceforge.net/
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/ctype.h>
#include <linux/inet.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/slab.h>
#include <linux/udp.h>
#include <linux/tcp.h>
#include <linux/skbuff.h>
#include <net/route.h>
#include <net/ip6_route.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_zones.h>
#include <linux/netfilter/nf_conntrack_h323.h>

/* Parameters */
static unsigned int default_rrq_ttl __read_mostly = 300;
module_param(default_rrq_ttl, uint, 0600);
MODULE_PARM_DESC(default_rrq_ttl, "use this TTL if it's missing in RRQ");

static int gkrouted_only __read_mostly = 1;
module_param(gkrouted_only, int, 0600);
MODULE_PARM_DESC(gkrouted_only, "only accept calls from gatekeeper");

static bool callforward_filter __read_mostly = true;
module_param(callforward_filter, bool, 0600);
MODULE_PARM_DESC(callforward_filter, "only create call forwarding expectations "
				     "if both endpoints are on different sides "
				     "(determined by routing information)");

/* Hooks for NAT */
int (*set_h245_addr_hook) (struct sk_buff *skb, unsigned int protoff,
			   unsigned char **data, int dataoff,
			   H245_TransportAddress *taddr,
			   union nf_inet_addr *addr, __be16 port)
			   __read_mostly;
int (*set_h225_addr_hook) (struct sk_buff *skb, unsigned int protoff,
			   unsigned char **data, int dataoff,
			   TransportAddress *taddr,
			   union nf_inet_addr *addr, __be16 port)
			   __read_mostly;
int (*set_sig_addr_hook) (struct sk_buff *skb,
			  struct nf_conn *ct,
			  enum ip_conntrack_info ctinfo,
			  unsigned int protoff, unsigned char **data,
			  TransportAddress *taddr, int count) __read_mostly;
int (*set_ras_addr_hook) (struct sk_buff *skb,
			  struct nf_conn *ct,
			  enum ip_conntrack_info ctinfo,
			  unsigned int protoff, unsigned char **data,
			  TransportAddress *taddr, int count) __read_mostly;
int (*nat_rtp_rtcp_hook) (struct sk_buff *skb,
			  struct nf_conn *ct,
			  enum ip_conntrack_info ctinfo,
			  unsigned int protoff,
			  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) __read_mostly;
int (*nat_t120_hook) (struct sk_buff *skb,
		      struct nf_conn *ct,
		      enum ip_conntrack_info ctinfo,
		      unsigned int protoff,
		      unsigned char **data, int dataoff,
		      H245_TransportAddress *taddr, __be16 port,
		      struct nf_conntrack_expect *exp) __read_mostly;
int (*nat_h245_hook) (struct sk_buff *skb,
		      struct nf_conn *ct,
		      enum ip_conntrack_info ctinfo,
		      unsigned int protoff,
		      unsigned char **data, int dataoff,
		      TransportAddress *taddr, __be16 port,
		      struct nf_conntrack_expect *exp) __read_mostly;
int (*nat_callforwarding_hook) (struct sk_buff *skb,
				struct nf_conn *ct,
				enum ip_conntrack_info ctinfo,
				unsigned int protoff,
				unsigned char **data, int dataoff,
				TransportAddress *taddr, __be16 port,
				struct nf_conntrack_expect *exp) __read_mostly;
int (*nat_q931_hook) (struct sk_buff *skb,
		      struct nf_conn *ct,
		      enum ip_conntrack_info ctinfo,
		      unsigned int protoff,
		      unsigned char **data, TransportAddress *taddr, int idx,
		      __be16 port, struct nf_conntrack_expect *exp)
		      __read_mostly;

static DEFINE_SPINLOCK(nf_h323_lock);
static char *h323_buffer;

static struct nf_conntrack_helper nf_conntrack_helper_h245;
static struct nf_conntrack_helper nf_conntrack_helper_q931[];
static struct nf_conntrack_helper nf_conntrack_helper_ras[];

/****************************************************************************/
static int get_tpkt_data(struct sk_buff *skb, unsigned int protoff,
			 struct nf_conn *ct, enum ip_conntrack_info ctinfo,
			 unsigned char **data, int *datalen, int *dataoff)
{
	struct nf_ct_h323_master *info = nfct_help_data(ct);
	int dir = CTINFO2DIR(ctinfo);
	const struct tcphdr *th;
	struct tcphdr _tcph;
	int tcpdatalen;
	int tcpdataoff;
	unsigned char *tpkt;
	int tpktlen;
	int tpktoff;

	/* Get TCP header */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return 0;

	/* Get TCP data offset */
	tcpdataoff = protoff + th->doff * 4;

	/* Get TCP data length */
	tcpdatalen = skb->len - tcpdataoff;
	if (tcpdatalen <= 0)	/* No TCP data */
		goto clear_out;

	if (*data == NULL) {	/* first TPKT */
		/* Get first TPKT pointer */
		tpkt = skb_header_pointer(skb, tcpdataoff, tcpdatalen,
					  h323_buffer);
		BUG_ON(tpkt == NULL);

		/* Validate TPKT identifier */
		if (tcpdatalen < 4 || tpkt[0] != 0x03 || tpkt[1] != 0) {
			/* Netmeeting sends TPKT header and data separately */
			if (info->tpkt_len[dir] > 0) {
				pr_debug("nf_ct_h323: previous packet "
					 "indicated separate TPKT data of %hu "
					 "bytes\n", info->tpkt_len[dir]);
				if (info->tpkt_len[dir] <= tcpdatalen) {
					/* Yes, there was a TPKT header
					 * received */
					*data = tpkt;
					*datalen = info->tpkt_len[dir];
					*dataoff = 0;
					goto out;
				}

				/* Fragmented TPKT */
				pr_debug("nf_ct_h323: fragmented TPKT\n");
				goto clear_out;
			}

			/* It is not even a TPKT */
			return 0;
		}
		tpktoff = 0;
	} else {		/* Next TPKT */
		tpktoff = *dataoff + *datalen;
		tcpdatalen -= tpktoff;
		if (tcpdatalen <= 4)	/* No more TPKT */
			goto clear_out;
		tpkt = *data + *datalen;

		/* Validate TPKT identifier */
		if (tpkt[0] != 0x03 || tpkt[1] != 0)
			goto clear_out;
	}

	/* Validate TPKT length */
	tpktlen = tpkt[2] * 256 + tpkt[3];
	if (tpktlen < 4)
		goto clear_out;
	if (tpktlen > tcpdatalen) {
		if (tcpdatalen == 4) {	/* Separate TPKT header */
			/* Netmeeting sends TPKT header and data separately */
			pr_debug("nf_ct_h323: separate TPKT header indicates "
				 "there will be TPKT data of %hu bytes\n",
				 tpktlen - 4);
			info->tpkt_len[dir] = tpktlen - 4;
			return 0;
		}

		pr_debug("nf_ct_h323: incomplete TPKT (fragmented?)\n");
		goto clear_out;
	}

	/* This is the encapsulated data */
	*data = tpkt + 4;
	*datalen = tpktlen - 4;
	*dataoff = tpktoff + 4;

      out:
	/* Clear TPKT length */
	info->tpkt_len[dir] = 0;
	return 1;

      clear_out:
	info->tpkt_len[dir] = 0;
	return 0;
}

/****************************************************************************/
static int get_h245_addr(struct nf_conn *ct, const unsigned char *data,
			 H245_TransportAddress *taddr,
			 union nf_inet_addr *addr, __be16 *port)
{
	const unsigned char *p;
	int len;

	if (taddr->choice != eH245_TransportAddress_unicastAddress)
		return 0;

	switch (taddr->unicastAddress.choice) {
	case eUnicastAddress_iPAddress:
		if (nf_ct_l3num(ct) != AF_INET)
			return 0;
		p = data + taddr->unicastAddress.iPAddress.network;
		len = 4;
		break;
	case eUnicastAddress_iP6Address:
		if (nf_ct_l3num(ct) != AF_INET6)
			return 0;
		p = data + taddr->unicastAddress.iP6Address.network;
		len = 16;
		break;
	default:
		return 0;
	}

	memcpy(addr, p, len);
	memset((void *)addr + len, 0, sizeof(*addr) - len);
	memcpy(port, p + len, sizeof(__be16));

	return 1;
}

/****************************************************************************/
static int expect_rtp_rtcp(struct sk_buff *skb, struct nf_conn *ct,
			   enum ip_conntrack_info ctinfo,
			   unsigned int protoff,
			   unsigned char **data, int dataoff,
			   H245_TransportAddress *taddr)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	__be16 rtp_port, rtcp_port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *rtp_exp;
	struct nf_conntrack_expect *rtcp_exp;
	typeof(nat_rtp_rtcp_hook) nat_rtp_rtcp;

	/* Read RTP or RTCP address */
	if (!get_h245_addr(ct, *data, taddr, &addr, &port) ||
	    memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) ||
	    port == 0)
		return 0;

	/* RTP port is even */
	rtp_port = port & ~htons(1);
	rtcp_port = port | htons(1);

	/* Create expect for RTP */
	if ((rtp_exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(rtp_exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  IPPROTO_UDP, NULL, &rtp_port);

	/* Create expect for RTCP */
	if ((rtcp_exp = nf_ct_expect_alloc(ct)) == NULL) {
		nf_ct_expect_put(rtp_exp);
		return -1;
	}
	nf_ct_expect_init(rtcp_exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  IPPROTO_UDP, NULL, &rtcp_port);

	if (memcmp(&ct->tuplehash[dir].tuple.src.u3,
		   &ct->tuplehash[!dir].tuple.dst.u3,
		   sizeof(ct->tuplehash[dir].tuple.src.u3)) &&
		   (nat_rtp_rtcp = rcu_dereference(nat_rtp_rtcp_hook)) &&
		   nf_ct_l3num(ct) == NFPROTO_IPV4 &&
		   ct->status & IPS_NAT_MASK) {
		/* NAT needed */
		ret = nat_rtp_rtcp(skb, ct, ctinfo, protoff, data, dataoff,
				   taddr, port, rtp_port, rtp_exp, rtcp_exp);
	} else {		/* Conntrack only */
		if (nf_ct_expect_related(rtp_exp) == 0) {
			if (nf_ct_expect_related(rtcp_exp) == 0) {
				pr_debug("nf_ct_h323: expect RTP ");
				nf_ct_dump_tuple(&rtp_exp->tuple);
				pr_debug("nf_ct_h323: expect RTCP ");
				nf_ct_dump_tuple(&rtcp_exp->tuple);
			} else {
				nf_ct_unexpect_related(rtp_exp);
				ret = -1;
			}
		} else
			ret = -1;
	}

	nf_ct_expect_put(rtp_exp);
	nf_ct_expect_put(rtcp_exp);

	return ret;
}

/****************************************************************************/
static int expect_t120(struct sk_buff *skb,
		       struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, int dataoff,
		       H245_TransportAddress *taddr)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;
	typeof(nat_t120_hook) nat_t120;

	/* Read T.120 address */
	if (!get_h245_addr(ct, *data, taddr, &addr, &port) ||
	    memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) ||
	    port == 0)
		return 0;

	/* Create expect for T.120 connections */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  IPPROTO_TCP, NULL, &port);
	exp->flags = NF_CT_EXPECT_PERMANENT;	/* Accept multiple channels */

	if (memcmp(&ct->tuplehash[dir].tuple.src.u3,
		   &ct->tuplehash[!dir].tuple.dst.u3,
		   sizeof(ct->tuplehash[dir].tuple.src.u3)) &&
	    (nat_t120 = rcu_dereference(nat_t120_hook)) &&
	    nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		/* NAT needed */
		ret = nat_t120(skb, ct, ctinfo, protoff, data, dataoff, taddr,
			       port, exp);
	} else {		/* Conntrack only */
		if (nf_ct_expect_related(exp) == 0) {
			pr_debug("nf_ct_h323: expect T.120 ");
			nf_ct_dump_tuple(&exp->tuple);
		} else
			ret = -1;
	}

	nf_ct_expect_put(exp);

	return ret;
}

/****************************************************************************/
static int process_h245_channel(struct sk_buff *skb,
				struct nf_conn *ct,
				enum ip_conntrack_info ctinfo,
				unsigned int protoff,
				unsigned char **data, int dataoff,
				H2250LogicalChannelParameters *channel)
{
	int ret;

	if (channel->options & eH2250LogicalChannelParameters_mediaChannel) {
		/* RTP */
		ret = expect_rtp_rtcp(skb, ct, ctinfo, protoff, data, dataoff,
				      &channel->mediaChannel);
		if (ret < 0)
			return -1;
	}

	if (channel->
	    options & eH2250LogicalChannelParameters_mediaControlChannel) {
		/* RTCP */
		ret = expect_rtp_rtcp(skb, ct, ctinfo, protoff, data, dataoff,
				      &channel->mediaControlChannel);
		if (ret < 0)
			return -1;
	}

	return 0;
}

/****************************************************************************/
static int process_olc(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, int dataoff,
		       OpenLogicalChannel *olc)
{
	int ret;

	pr_debug("nf_ct_h323: OpenLogicalChannel\n");

	if (olc->forwardLogicalChannelParameters.multiplexParameters.choice ==
	    eOpenLogicalChannel_forwardLogicalChannelParameters_multiplexParameters_h2250LogicalChannelParameters)
	{
		ret = process_h245_channel(skb, ct, ctinfo,
					   protoff, data, dataoff,
					   &olc->
					   forwardLogicalChannelParameters.
					   multiplexParameters.
					   h2250LogicalChannelParameters);
		if (ret < 0)
			return -1;
	}

	if ((olc->options &
	     eOpenLogicalChannel_reverseLogicalChannelParameters) &&
	    (olc->reverseLogicalChannelParameters.options &
	     eOpenLogicalChannel_reverseLogicalChannelParameters_multiplexParameters)
	    && (olc->reverseLogicalChannelParameters.multiplexParameters.
		choice ==
		eOpenLogicalChannel_reverseLogicalChannelParameters_multiplexParameters_h2250LogicalChannelParameters))
	{
		ret =
		    process_h245_channel(skb, ct, ctinfo,
					 protoff, data, dataoff,
					 &olc->
					 reverseLogicalChannelParameters.
					 multiplexParameters.
					 h2250LogicalChannelParameters);
		if (ret < 0)
			return -1;
	}

	if ((olc->options & eOpenLogicalChannel_separateStack) &&
	    olc->forwardLogicalChannelParameters.dataType.choice ==
	    eDataType_data &&
	    olc->forwardLogicalChannelParameters.dataType.data.application.
	    choice == eDataApplicationCapability_application_t120 &&
	    olc->forwardLogicalChannelParameters.dataType.data.application.
	    t120.choice == eDataProtocolCapability_separateLANStack &&
	    olc->separateStack.networkAddress.choice ==
	    eNetworkAccessParameters_networkAddress_localAreaAddress) {
		ret = expect_t120(skb, ct, ctinfo, protoff, data, dataoff,
				  &olc->separateStack.networkAddress.
				  localAreaAddress);
		if (ret < 0)
			return -1;
	}

	return 0;
}

/****************************************************************************/
static int process_olca(struct sk_buff *skb, struct nf_conn *ct,
			enum ip_conntrack_info ctinfo,
			unsigned int protoff, unsigned char **data, int dataoff,
			OpenLogicalChannelAck *olca)
{
	H2250LogicalChannelAckParameters *ack;
	int ret;

	pr_debug("nf_ct_h323: OpenLogicalChannelAck\n");

	if ((olca->options &
	     eOpenLogicalChannelAck_reverseLogicalChannelParameters) &&
	    (olca->reverseLogicalChannelParameters.options &
	     eOpenLogicalChannelAck_reverseLogicalChannelParameters_multiplexParameters)
	    && (olca->reverseLogicalChannelParameters.multiplexParameters.
		choice ==
		eOpenLogicalChannelAck_reverseLogicalChannelParameters_multiplexParameters_h2250LogicalChannelParameters))
	{
		ret = process_h245_channel(skb, ct, ctinfo,
					   protoff, data, dataoff,
					   &olca->
					   reverseLogicalChannelParameters.
					   multiplexParameters.
					   h2250LogicalChannelParameters);
		if (ret < 0)
			return -1;
	}

	if ((olca->options &
	     eOpenLogicalChannelAck_forwardMultiplexAckParameters) &&
	    (olca->forwardMultiplexAckParameters.choice ==
	     eOpenLogicalChannelAck_forwardMultiplexAckParameters_h2250LogicalChannelAckParameters))
	{
		ack = &olca->forwardMultiplexAckParameters.
		    h2250LogicalChannelAckParameters;
		if (ack->options &
		    eH2250LogicalChannelAckParameters_mediaChannel) {
			/* RTP */
			ret = expect_rtp_rtcp(skb, ct, ctinfo,
					      protoff, data, dataoff,
					      &ack->mediaChannel);
			if (ret < 0)
				return -1;
		}

		if (ack->options &
		    eH2250LogicalChannelAckParameters_mediaControlChannel) {
			/* RTCP */
			ret = expect_rtp_rtcp(skb, ct, ctinfo,
					      protoff, data, dataoff,
					      &ack->mediaControlChannel);
			if (ret < 0)
				return -1;
		}
	}

	if ((olca->options & eOpenLogicalChannelAck_separateStack) &&
		olca->separateStack.networkAddress.choice ==
		eNetworkAccessParameters_networkAddress_localAreaAddress) {
		ret = expect_t120(skb, ct, ctinfo, protoff, data, dataoff,
				  &olca->separateStack.networkAddress.
				  localAreaAddress);
		if (ret < 0)
			return -1;
	}

	return 0;
}

/****************************************************************************/
static int process_h245(struct sk_buff *skb, struct nf_conn *ct,
			enum ip_conntrack_info ctinfo,
			unsigned int protoff, unsigned char **data, int dataoff,
			MultimediaSystemControlMessage *mscm)
{
	switch (mscm->choice) {
	case eMultimediaSystemControlMessage_request:
		if (mscm->request.choice ==
		    eRequestMessage_openLogicalChannel) {
			return process_olc(skb, ct, ctinfo,
					   protoff, data, dataoff,
					   &mscm->request.openLogicalChannel);
		}
		pr_debug("nf_ct_h323: H.245 Request %d\n",
			 mscm->request.choice);
		break;
	case eMultimediaSystemControlMessage_response:
		if (mscm->response.choice ==
		    eResponseMessage_openLogicalChannelAck) {
			return process_olca(skb, ct, ctinfo,
					    protoff, data, dataoff,
					    &mscm->response.
					    openLogicalChannelAck);
		}
		pr_debug("nf_ct_h323: H.245 Response %d\n",
			 mscm->response.choice);
		break;
	default:
		pr_debug("nf_ct_h323: H.245 signal %d\n", mscm->choice);
		break;
	}

	return 0;
}

/****************************************************************************/
static int h245_help(struct sk_buff *skb, unsigned int protoff,
		     struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	static MultimediaSystemControlMessage mscm;
	unsigned char *data = NULL;
	int datalen;
	int dataoff;
	int ret;

	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	pr_debug("nf_ct_h245: skblen = %u\n", skb->len);

	spin_lock_bh(&nf_h323_lock);

	/* Process each TPKT */
	while (get_tpkt_data(skb, protoff, ct, ctinfo,
			     &data, &datalen, &dataoff)) {
		pr_debug("nf_ct_h245: TPKT len=%d ", datalen);
		nf_ct_dump_tuple(&ct->tuplehash[CTINFO2DIR(ctinfo)].tuple);

		/* Decode H.245 signal */
		ret = DecodeMultimediaSystemControlMessage(data, datalen,
							   &mscm);
		if (ret < 0) {
			pr_debug("nf_ct_h245: decoding error: %s\n",
				 ret == H323_ERROR_BOUND ?
				 "out of bound" : "out of range");
			/* We don't drop when decoding error */
			break;
		}

		/* Process H.245 signal */
		if (process_h245(skb, ct, ctinfo, protoff,
				 &data, dataoff, &mscm) < 0)
			goto drop;
	}

	spin_unlock_bh(&nf_h323_lock);
	return NF_ACCEPT;

      drop:
	spin_unlock_bh(&nf_h323_lock);
	nf_ct_helper_log(skb, ct, "cannot process H.245 message");
	return NF_DROP;
}

/****************************************************************************/
static const struct nf_conntrack_expect_policy h245_exp_policy = {
	.max_expected	= H323_RTP_CHANNEL_MAX * 4 + 2 /* T.120 */,
	.timeout	= 240,
};

static struct nf_conntrack_helper nf_conntrack_helper_h245 __read_mostly = {
	.name			= "H.245",
	.me			= THIS_MODULE,
	.data_len		= sizeof(struct nf_ct_h323_master),
	.tuple.src.l3num	= AF_UNSPEC,
	.tuple.dst.protonum	= IPPROTO_UDP,
	.help			= h245_help,
	.expect_policy		= &h245_exp_policy,
};

/****************************************************************************/
int get_h225_addr(struct nf_conn *ct, unsigned char *data,
		  TransportAddress *taddr,
		  union nf_inet_addr *addr, __be16 *port)
{
	const unsigned char *p;
	int len;

	switch (taddr->choice) {
	case eTransportAddress_ipAddress:
		if (nf_ct_l3num(ct) != AF_INET)
			return 0;
		p = data + taddr->ipAddress.ip;
		len = 4;
		break;
	case eTransportAddress_ip6Address:
		if (nf_ct_l3num(ct) != AF_INET6)
			return 0;
		p = data + taddr->ip6Address.ip;
		len = 16;
		break;
	default:
		return 0;
	}

	memcpy(addr, p, len);
	memset((void *)addr + len, 0, sizeof(*addr) - len);
	memcpy(port, p + len, sizeof(__be16));

	return 1;
}

/****************************************************************************/
static int expect_h245(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff, unsigned char **data, int dataoff,
		       TransportAddress *taddr)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;
	typeof(nat_h245_hook) nat_h245;

	/* Read h245Address */
	if (!get_h225_addr(ct, *data, taddr, &addr, &port) ||
	    memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) ||
	    port == 0)
		return 0;

	/* Create expect for h245 connection */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  IPPROTO_TCP, NULL, &port);
	exp->helper = &nf_conntrack_helper_h245;

	if (memcmp(&ct->tuplehash[dir].tuple.src.u3,
		   &ct->tuplehash[!dir].tuple.dst.u3,
		   sizeof(ct->tuplehash[dir].tuple.src.u3)) &&
	    (nat_h245 = rcu_dereference(nat_h245_hook)) &&
	    nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		/* NAT needed */
		ret = nat_h245(skb, ct, ctinfo, protoff, data, dataoff, taddr,
			       port, exp);
	} else {		/* Conntrack only */
		if (nf_ct_expect_related(exp) == 0) {
			pr_debug("nf_ct_q931: expect H.245 ");
			nf_ct_dump_tuple(&exp->tuple);
		} else
			ret = -1;
	}

	nf_ct_expect_put(exp);

	return ret;
}

/* If the calling party is on the same side of the forward-to party,
 * we don't need to track the second call */
static int callforward_do_filter(struct net *net,
				 const union nf_inet_addr *src,
				 const union nf_inet_addr *dst,
				 u_int8_t family)
{
	const struct nf_afinfo *afinfo;
	int ret = 0;

	/* rcu_read_lock()ed by nf_hook_slow() */
	afinfo = nf_get_afinfo(family);
	if (!afinfo)
		return 0;

	switch (family) {
	case AF_INET: {
		struct flowi4 fl1, fl2;
		struct rtable *rt1, *rt2;

		memset(&fl1, 0, sizeof(fl1));
		fl1.daddr = src->ip;

		memset(&fl2, 0, sizeof(fl2));
		fl2.daddr = dst->ip;
		if (!afinfo->route(net, (struct dst_entry **)&rt1,
				   flowi4_to_flowi(&fl1), false)) {
			if (!afinfo->route(net, (struct dst_entry **)&rt2,
					   flowi4_to_flowi(&fl2), false)) {
				if (rt_nexthop(rt1, fl1.daddr) ==
				    rt_nexthop(rt2, fl2.daddr) &&
				    rt1->dst.dev  == rt2->dst.dev)
					ret = 1;
				dst_release(&rt2->dst);
			}
			dst_release(&rt1->dst);
		}
		break;
	}
#if IS_ENABLED(CONFIG_NF_CONNTRACK_IPV6)
	case AF_INET6: {
		struct flowi6 fl1, fl2;
		struct rt6_info *rt1, *rt2;

		memset(&fl1, 0, sizeof(fl1));
		fl1.daddr = src->in6;

		memset(&fl2, 0, sizeof(fl2));
		fl2.daddr = dst->in6;
		if (!afinfo->route(net, (struct dst_entry **)&rt1,
				   flowi6_to_flowi(&fl1), false)) {
			if (!afinfo->route(net, (struct dst_entry **)&rt2,
					   flowi6_to_flowi(&fl2), false)) {
				if (ipv6_addr_equal(rt6_nexthop(rt1, &fl1.daddr),
						    rt6_nexthop(rt2, &fl2.daddr)) &&
				    rt1->dst.dev == rt2->dst.dev)
					ret = 1;
				dst_release(&rt2->dst);
			}
			dst_release(&rt1->dst);
		}
		break;
	}
#endif
	}
	return ret;

}

/****************************************************************************/
static int expect_callforwarding(struct sk_buff *skb,
				 struct nf_conn *ct,
				 enum ip_conntrack_info ctinfo,
				 unsigned int protoff,
				 unsigned char **data, int dataoff,
				 TransportAddress *taddr)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;
	struct net *net = nf_ct_net(ct);
	typeof(nat_callforwarding_hook) nat_callforwarding;

	/* Read alternativeAddress */
	if (!get_h225_addr(ct, *data, taddr, &addr, &port) || port == 0)
		return 0;

	/* If the calling party is on the same side of the forward-to party,
	 * we don't need to track the second call */
	if (callforward_filter &&
	    callforward_do_filter(net, &addr, &ct->tuplehash[!dir].tuple.src.u3,
				  nf_ct_l3num(ct))) {
		pr_debug("nf_ct_q931: Call Forwarding not tracked\n");
		return 0;
	}

	/* Create expect for the second call leg */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3, &addr,
			  IPPROTO_TCP, NULL, &port);
	exp->helper = nf_conntrack_helper_q931;

	if (memcmp(&ct->tuplehash[dir].tuple.src.u3,
		   &ct->tuplehash[!dir].tuple.dst.u3,
		   sizeof(ct->tuplehash[dir].tuple.src.u3)) &&
	    (nat_callforwarding = rcu_dereference(nat_callforwarding_hook)) &&
	    nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		/* Need NAT */
		ret = nat_callforwarding(skb, ct, ctinfo,
					 protoff, data, dataoff,
					 taddr, port, exp);
	} else {		/* Conntrack only */
		if (nf_ct_expect_related(exp) == 0) {
			pr_debug("nf_ct_q931: expect Call Forwarding ");
			nf_ct_dump_tuple(&exp->tuple);
		} else
			ret = -1;
	}

	nf_ct_expect_put(exp);

	return ret;
}

/****************************************************************************/
static int process_setup(struct sk_buff *skb, struct nf_conn *ct,
			 enum ip_conntrack_info ctinfo,
			 unsigned int protoff,
			 unsigned char **data, int dataoff,
			 Setup_UUIE *setup)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret;
	int i;
	__be16 port;
	union nf_inet_addr addr;
	typeof(set_h225_addr_hook) set_h225_addr;

	pr_debug("nf_ct_q931: Setup\n");

	if (setup->options & eSetup_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &setup->h245Address);
		if (ret < 0)
			return -1;
	}

	set_h225_addr = rcu_dereference(set_h225_addr_hook);
	if ((setup->options & eSetup_UUIE_destCallSignalAddress) &&
	    (set_h225_addr) && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK &&
	    get_h225_addr(ct, *data, &setup->destCallSignalAddress,
			  &addr, &port) &&
	    memcmp(&addr, &ct->tuplehash[!dir].tuple.src.u3, sizeof(addr))) {
		pr_debug("nf_ct_q931: set destCallSignalAddress %pI6:%hu->%pI6:%hu\n",
			 &addr, ntohs(port), &ct->tuplehash[!dir].tuple.src.u3,
			 ntohs(ct->tuplehash[!dir].tuple.src.u.tcp.port));
		ret = set_h225_addr(skb, protoff, data, dataoff,
				    &setup->destCallSignalAddress,
				    &ct->tuplehash[!dir].tuple.src.u3,
				    ct->tuplehash[!dir].tuple.src.u.tcp.port);
		if (ret < 0)
			return -1;
	}

	if ((setup->options & eSetup_UUIE_sourceCallSignalAddress) &&
	    (set_h225_addr) && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK &&
	    get_h225_addr(ct, *data, &setup->sourceCallSignalAddress,
			  &addr, &port) &&
	    memcmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3, sizeof(addr))) {
		pr_debug("nf_ct_q931: set sourceCallSignalAddress %pI6:%hu->%pI6:%hu\n",
			 &addr, ntohs(port), &ct->tuplehash[!dir].tuple.dst.u3,
			 ntohs(ct->tuplehash[!dir].tuple.dst.u.tcp.port));
		ret = set_h225_addr(skb, protoff, data, dataoff,
				    &setup->sourceCallSignalAddress,
				    &ct->tuplehash[!dir].tuple.dst.u3,
				    ct->tuplehash[!dir].tuple.dst.u.tcp.port);
		if (ret < 0)
			return -1;
	}

	if (setup->options & eSetup_UUIE_fastStart) {
		for (i = 0; i < setup->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &setup->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_callproceeding(struct sk_buff *skb,
				  struct nf_conn *ct,
				  enum ip_conntrack_info ctinfo,
				  unsigned int protoff,
				  unsigned char **data, int dataoff,
				  CallProceeding_UUIE *callproc)
{
	int ret;
	int i;

	pr_debug("nf_ct_q931: CallProceeding\n");

	if (callproc->options & eCallProceeding_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &callproc->h245Address);
		if (ret < 0)
			return -1;
	}

	if (callproc->options & eCallProceeding_UUIE_fastStart) {
		for (i = 0; i < callproc->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &callproc->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_connect(struct sk_buff *skb, struct nf_conn *ct,
			   enum ip_conntrack_info ctinfo,
			   unsigned int protoff,
			   unsigned char **data, int dataoff,
			   Connect_UUIE *connect)
{
	int ret;
	int i;

	pr_debug("nf_ct_q931: Connect\n");

	if (connect->options & eConnect_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &connect->h245Address);
		if (ret < 0)
			return -1;
	}

	if (connect->options & eConnect_UUIE_fastStart) {
		for (i = 0; i < connect->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &connect->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_alerting(struct sk_buff *skb, struct nf_conn *ct,
			    enum ip_conntrack_info ctinfo,
			    unsigned int protoff,
			    unsigned char **data, int dataoff,
			    Alerting_UUIE *alert)
{
	int ret;
	int i;

	pr_debug("nf_ct_q931: Alerting\n");

	if (alert->options & eAlerting_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &alert->h245Address);
		if (ret < 0)
			return -1;
	}

	if (alert->options & eAlerting_UUIE_fastStart) {
		for (i = 0; i < alert->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &alert->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_facility(struct sk_buff *skb, struct nf_conn *ct,
			    enum ip_conntrack_info ctinfo,
			    unsigned int protoff,
			    unsigned char **data, int dataoff,
			    Facility_UUIE *facility)
{
	int ret;
	int i;

	pr_debug("nf_ct_q931: Facility\n");

	if (facility->reason.choice == eFacilityReason_callForwarded) {
		if (facility->options & eFacility_UUIE_alternativeAddress)
			return expect_callforwarding(skb, ct, ctinfo,
						     protoff, data, dataoff,
						     &facility->
						     alternativeAddress);
		return 0;
	}

	if (facility->options & eFacility_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &facility->h245Address);
		if (ret < 0)
			return -1;
	}

	if (facility->options & eFacility_UUIE_fastStart) {
		for (i = 0; i < facility->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &facility->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_progress(struct sk_buff *skb, struct nf_conn *ct,
			    enum ip_conntrack_info ctinfo,
			    unsigned int protoff,
			    unsigned char **data, int dataoff,
			    Progress_UUIE *progress)
{
	int ret;
	int i;

	pr_debug("nf_ct_q931: Progress\n");

	if (progress->options & eProgress_UUIE_h245Address) {
		ret = expect_h245(skb, ct, ctinfo, protoff, data, dataoff,
				  &progress->h245Address);
		if (ret < 0)
			return -1;
	}

	if (progress->options & eProgress_UUIE_fastStart) {
		for (i = 0; i < progress->fastStart.count; i++) {
			ret = process_olc(skb, ct, ctinfo,
					  protoff, data, dataoff,
					  &progress->fastStart.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int process_q931(struct sk_buff *skb, struct nf_conn *ct,
			enum ip_conntrack_info ctinfo,
			unsigned int protoff, unsigned char **data, int dataoff,
			Q931 *q931)
{
	H323_UU_PDU *pdu = &q931->UUIE.h323_uu_pdu;
	int i;
	int ret = 0;

	switch (pdu->h323_message_body.choice) {
	case eH323_UU_PDU_h323_message_body_setup:
		ret = process_setup(skb, ct, ctinfo, protoff, data, dataoff,
				    &pdu->h323_message_body.setup);
		break;
	case eH323_UU_PDU_h323_message_body_callProceeding:
		ret = process_callproceeding(skb, ct, ctinfo,
					     protoff, data, dataoff,
					     &pdu->h323_message_body.
					     callProceeding);
		break;
	case eH323_UU_PDU_h323_message_body_connect:
		ret = process_connect(skb, ct, ctinfo, protoff, data, dataoff,
				      &pdu->h323_message_body.connect);
		break;
	case eH323_UU_PDU_h323_message_body_alerting:
		ret = process_alerting(skb, ct, ctinfo, protoff, data, dataoff,
				       &pdu->h323_message_body.alerting);
		break;
	case eH323_UU_PDU_h323_message_body_facility:
		ret = process_facility(skb, ct, ctinfo, protoff, data, dataoff,
				       &pdu->h323_message_body.facility);
		break;
	case eH323_UU_PDU_h323_message_body_progress:
		ret = process_progress(skb, ct, ctinfo, protoff, data, dataoff,
				       &pdu->h323_message_body.progress);
		break;
	default:
		pr_debug("nf_ct_q931: Q.931 signal %d\n",
			 pdu->h323_message_body.choice);
		break;
	}

	if (ret < 0)
		return -1;

	if (pdu->options & eH323_UU_PDU_h245Control) {
		for (i = 0; i < pdu->h245Control.count; i++) {
			ret = process_h245(skb, ct, ctinfo,
					   protoff, data, dataoff,
					   &pdu->h245Control.item[i]);
			if (ret < 0)
				return -1;
		}
	}

	return 0;
}

/****************************************************************************/
static int q931_help(struct sk_buff *skb, unsigned int protoff,
		     struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	static Q931 q931;
	unsigned char *data = NULL;
	int datalen;
	int dataoff;
	int ret;

	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED && ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	pr_debug("nf_ct_q931: skblen = %u\n", skb->len);

	spin_lock_bh(&nf_h323_lock);

	/* Process each TPKT */
	while (get_tpkt_data(skb, protoff, ct, ctinfo,
			     &data, &datalen, &dataoff)) {
		pr_debug("nf_ct_q931: TPKT len=%d ", datalen);
		nf_ct_dump_tuple(&ct->tuplehash[CTINFO2DIR(ctinfo)].tuple);

		/* Decode Q.931 signal */
		ret = DecodeQ931(data, datalen, &q931);
		if (ret < 0) {
			pr_debug("nf_ct_q931: decoding error: %s\n",
				 ret == H323_ERROR_BOUND ?
				 "out of bound" : "out of range");
			/* We don't drop when decoding error */
			break;
		}

		/* Process Q.931 signal */
		if (process_q931(skb, ct, ctinfo, protoff,
				 &data, dataoff, &q931) < 0)
			goto drop;
	}

	spin_unlock_bh(&nf_h323_lock);
	return NF_ACCEPT;

      drop:
	spin_unlock_bh(&nf_h323_lock);
	nf_ct_helper_log(skb, ct, "cannot process Q.931 message");
	return NF_DROP;
}

/****************************************************************************/
static const struct nf_conntrack_expect_policy q931_exp_policy = {
	/* T.120 and H.245 */
	.max_expected		= H323_RTP_CHANNEL_MAX * 4 + 4,
	.timeout		= 240,
};

static struct nf_conntrack_helper nf_conntrack_helper_q931[] __read_mostly = {
	{
		.name			= "Q.931",
		.me			= THIS_MODULE,
		.data_len		= sizeof(struct nf_ct_h323_master),
		.tuple.src.l3num	= AF_INET,
		.tuple.src.u.tcp.port	= cpu_to_be16(Q931_PORT),
		.tuple.dst.protonum	= IPPROTO_TCP,
		.help			= q931_help,
		.expect_policy		= &q931_exp_policy,
	},
	{
		.name			= "Q.931",
		.me			= THIS_MODULE,
		.tuple.src.l3num	= AF_INET6,
		.tuple.src.u.tcp.port	= cpu_to_be16(Q931_PORT),
		.tuple.dst.protonum	= IPPROTO_TCP,
		.help			= q931_help,
		.expect_policy		= &q931_exp_policy,
	},
};

/****************************************************************************/
static unsigned char *get_udp_data(struct sk_buff *skb, unsigned int protoff,
				   int *datalen)
{
	const struct udphdr *uh;
	struct udphdr _uh;
	int dataoff;

	uh = skb_header_pointer(skb, protoff, sizeof(_uh), &_uh);
	if (uh == NULL)
		return NULL;
	dataoff = protoff + sizeof(_uh);
	if (dataoff >= skb->len)
		return NULL;
	*datalen = skb->len - dataoff;
	return skb_header_pointer(skb, dataoff, *datalen, h323_buffer);
}

/****************************************************************************/
static struct nf_conntrack_expect *find_expect(struct nf_conn *ct,
					       union nf_inet_addr *addr,
					       __be16 port)
{
	struct net *net = nf_ct_net(ct);
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple tuple;

	memset(&tuple.src.u3, 0, sizeof(tuple.src.u3));
	tuple.src.u.tcp.port = 0;
	memcpy(&tuple.dst.u3, addr, sizeof(tuple.dst.u3));
	tuple.dst.u.tcp.port = port;
	tuple.dst.protonum = IPPROTO_TCP;

	exp = __nf_ct_expect_find(net, nf_ct_zone(ct), &tuple);
	if (exp && exp->master == ct)
		return exp;
	return NULL;
}

/****************************************************************************/
static int set_expect_timeout(struct nf_conntrack_expect *exp,
			      unsigned int timeout)
{
	if (!exp || !del_timer(&exp->timeout))
		return 0;

	exp->timeout.expires = jiffies + timeout * HZ;
	add_timer(&exp->timeout);

	return 1;
}

/****************************************************************************/
static int expect_q931(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff, unsigned char **data,
		       TransportAddress *taddr, int count)
{
	struct nf_ct_h323_master *info = nfct_help_data(ct);
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	int i;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;
	typeof(nat_q931_hook) nat_q931;

	/* Look for the first related address */
	for (i = 0; i < count; i++) {
		if (get_h225_addr(ct, *data, &taddr[i], &addr, &port) &&
		    memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3,
			   sizeof(addr)) == 0 && port != 0)
			break;
	}

	if (i >= count)		/* Not found */
		return 0;

	/* Create expect for Q.931 */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  gkrouted_only ? /* only accept calls from GK? */
				&ct->tuplehash[!dir].tuple.src.u3 : NULL,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  IPPROTO_TCP, NULL, &port);
	exp->helper = nf_conntrack_helper_q931;
	exp->flags = NF_CT_EXPECT_PERMANENT;	/* Accept multiple calls */

	nat_q931 = rcu_dereference(nat_q931_hook);
	if (nat_q931 && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {	/* Need NAT */
		ret = nat_q931(skb, ct, ctinfo, protoff, data,
			       taddr, i, port, exp);
	} else {		/* Conntrack only */
		if (nf_ct_expect_related(exp) == 0) {
			pr_debug("nf_ct_ras: expect Q.931 ");
			nf_ct_dump_tuple(&exp->tuple);

			/* Save port for looking up expect in processing RCF */
			info->sig_port[dir] = port;
		} else
			ret = -1;
	}

	nf_ct_expect_put(exp);

	return ret;
}

/****************************************************************************/
static int process_grq(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, GatekeeperRequest *grq)
{
	typeof(set_ras_addr_hook) set_ras_addr;

	pr_debug("nf_ct_ras: GRQ\n");

	set_ras_addr = rcu_dereference(set_ras_addr_hook);
	if (set_ras_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK)	/* NATed */
		return set_ras_addr(skb, ct, ctinfo, protoff, data,
				    &grq->rasAddress, 1);
	return 0;
}

/****************************************************************************/
static int process_gcf(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, GatekeeperConfirm *gcf)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;

	pr_debug("nf_ct_ras: GCF\n");

	if (!get_h225_addr(ct, *data, &gcf->rasAddress, &addr, &port))
		return 0;

	/* Registration port is the same as discovery port */
	if (!memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) &&
	    port == ct->tuplehash[dir].tuple.src.u.udp.port)
		return 0;

	/* Avoid RAS expectation loops. A GCF is never expected. */
	if (test_bit(IPS_EXPECTED_BIT, &ct->status))
		return 0;

	/* Need new expect */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3, &addr,
			  IPPROTO_UDP, NULL, &port);
	exp->helper = nf_conntrack_helper_ras;

	if (nf_ct_expect_related(exp) == 0) {
		pr_debug("nf_ct_ras: expect RAS ");
		nf_ct_dump_tuple(&exp->tuple);
	} else
		ret = -1;

	nf_ct_expect_put(exp);

	return ret;
}

/****************************************************************************/
static int process_rrq(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, RegistrationRequest *rrq)
{
	struct nf_ct_h323_master *info = nfct_help_data(ct);
	int ret;
	typeof(set_ras_addr_hook) set_ras_addr;

	pr_debug("nf_ct_ras: RRQ\n");

	ret = expect_q931(skb, ct, ctinfo, protoff, data,
			  rrq->callSignalAddress.item,
			  rrq->callSignalAddress.count);
	if (ret < 0)
		return -1;

	set_ras_addr = rcu_dereference(set_ras_addr_hook);
	if (set_ras_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		ret = set_ras_addr(skb, ct, ctinfo, protoff, data,
				   rrq->rasAddress.item,
				   rrq->rasAddress.count);
		if (ret < 0)
			return -1;
	}

	if (rrq->options & eRegistrationRequest_timeToLive) {
		pr_debug("nf_ct_ras: RRQ TTL = %u seconds\n", rrq->timeToLive);
		info->timeout = rrq->timeToLive;
	} else
		info->timeout = default_rrq_ttl;

	return 0;
}

/****************************************************************************/
static int process_rcf(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, RegistrationConfirm *rcf)
{
	struct nf_ct_h323_master *info = nfct_help_data(ct);
	int dir = CTINFO2DIR(ctinfo);
	int ret;
	struct nf_conntrack_expect *exp;
	typeof(set_sig_addr_hook) set_sig_addr;

	pr_debug("nf_ct_ras: RCF\n");

	set_sig_addr = rcu_dereference(set_sig_addr_hook);
	if (set_sig_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		ret = set_sig_addr(skb, ct, ctinfo, protoff, data,
					rcf->callSignalAddress.item,
					rcf->callSignalAddress.count);
		if (ret < 0)
			return -1;
	}

	if (rcf->options & eRegistrationConfirm_timeToLive) {
		pr_debug("nf_ct_ras: RCF TTL = %u seconds\n", rcf->timeToLive);
		info->timeout = rcf->timeToLive;
	}

	if (info->timeout > 0) {
		pr_debug("nf_ct_ras: set RAS connection timeout to "
			 "%u seconds\n", info->timeout);
		nf_ct_refresh(ct, skb, info->timeout * HZ);

		/* Set expect timeout */
		spin_lock_bh(&nf_conntrack_expect_lock);
		exp = find_expect(ct, &ct->tuplehash[dir].tuple.dst.u3,
				  info->sig_port[!dir]);
		if (exp) {
			pr_debug("nf_ct_ras: set Q.931 expect "
				 "timeout to %u seconds for",
				 info->timeout);
			nf_ct_dump_tuple(&exp->tuple);
			set_expect_timeout(exp, info->timeout);
		}
		spin_unlock_bh(&nf_conntrack_expect_lock);
	}

	return 0;
}

/****************************************************************************/
static int process_urq(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, UnregistrationRequest *urq)
{
	struct nf_ct_h323_master *info = nfct_help_data(ct);
	int dir = CTINFO2DIR(ctinfo);
	int ret;
	typeof(set_sig_addr_hook) set_sig_addr;

	pr_debug("nf_ct_ras: URQ\n");

	set_sig_addr = rcu_dereference(set_sig_addr_hook);
	if (set_sig_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		ret = set_sig_addr(skb, ct, ctinfo, protoff, data,
				   urq->callSignalAddress.item,
				   urq->callSignalAddress.count);
		if (ret < 0)
			return -1;
	}

	/* Clear old expect */
	nf_ct_remove_expectations(ct);
	info->sig_port[dir] = 0;
	info->sig_port[!dir] = 0;

	/* Give it 30 seconds for UCF or URJ */
	nf_ct_refresh(ct, skb, 30 * HZ);

	return 0;
}

/****************************************************************************/
static int process_arq(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, AdmissionRequest *arq)
{
	const struct nf_ct_h323_master *info = nfct_help_data(ct);
	int dir = CTINFO2DIR(ctinfo);
	__be16 port;
	union nf_inet_addr addr;
	typeof(set_h225_addr_hook) set_h225_addr;

	pr_debug("nf_ct_ras: ARQ\n");

	set_h225_addr = rcu_dereference(set_h225_addr_hook);
	if ((arq->options & eAdmissionRequest_destCallSignalAddress) &&
	    get_h225_addr(ct, *data, &arq->destCallSignalAddress,
			  &addr, &port) &&
	    !memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) &&
	    port == info->sig_port[dir] &&
	    nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    set_h225_addr && ct->status & IPS_NAT_MASK) {
		/* Answering ARQ */
		return set_h225_addr(skb, protoff, data, 0,
				     &arq->destCallSignalAddress,
				     &ct->tuplehash[!dir].tuple.dst.u3,
				     info->sig_port[!dir]);
	}

	if ((arq->options & eAdmissionRequest_srcCallSignalAddress) &&
	    get_h225_addr(ct, *data, &arq->srcCallSignalAddress,
			  &addr, &port) &&
	    !memcmp(&addr, &ct->tuplehash[dir].tuple.src.u3, sizeof(addr)) &&
	    set_h225_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		/* Calling ARQ */
		return set_h225_addr(skb, protoff, data, 0,
				     &arq->srcCallSignalAddress,
				     &ct->tuplehash[!dir].tuple.dst.u3,
				     port);
	}

	return 0;
}

/****************************************************************************/
static int process_acf(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, AdmissionConfirm *acf)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;
	typeof(set_sig_addr_hook) set_sig_addr;

	pr_debug("nf_ct_ras: ACF\n");

	if (!get_h225_addr(ct, *data, &acf->destCallSignalAddress,
			   &addr, &port))
		return 0;

	if (!memcmp(&addr, &ct->tuplehash[dir].tuple.dst.u3, sizeof(addr))) {
		/* Answering ACF */
		set_sig_addr = rcu_dereference(set_sig_addr_hook);
		if (set_sig_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
		    ct->status & IPS_NAT_MASK)
			return set_sig_addr(skb, ct, ctinfo, protoff, data,
					    &acf->destCallSignalAddress, 1);
		return 0;
	}

	/* Need new expect */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3, &addr,
			  IPPROTO_TCP, NULL, &port);
	exp->flags = NF_CT_EXPECT_PERMANENT;
	exp->helper = nf_conntrack_helper_q931;

	if (nf_ct_expect_related(exp) == 0) {
		pr_debug("nf_ct_ras: expect Q.931 ");
		nf_ct_dump_tuple(&exp->tuple);
	} else
		ret = -1;

	nf_ct_expect_put(exp);

	return ret;
}

/****************************************************************************/
static int process_lrq(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, LocationRequest *lrq)
{
	typeof(set_ras_addr_hook) set_ras_addr;

	pr_debug("nf_ct_ras: LRQ\n");

	set_ras_addr = rcu_dereference(set_ras_addr_hook);
	if (set_ras_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK)
		return set_ras_addr(skb, ct, ctinfo, protoff, data,
				    &lrq->replyAddress, 1);
	return 0;
}

/****************************************************************************/
static int process_lcf(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, LocationConfirm *lcf)
{
	int dir = CTINFO2DIR(ctinfo);
	int ret = 0;
	__be16 port;
	union nf_inet_addr addr;
	struct nf_conntrack_expect *exp;

	pr_debug("nf_ct_ras: LCF\n");

	if (!get_h225_addr(ct, *data, &lcf->callSignalAddress,
			   &addr, &port))
		return 0;

	/* Need new expect for call signal */
	if ((exp = nf_ct_expect_alloc(ct)) == NULL)
		return -1;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &ct->tuplehash[!dir].tuple.src.u3, &addr,
			  IPPROTO_TCP, NULL, &port);
	exp->flags = NF_CT_EXPECT_PERMANENT;
	exp->helper = nf_conntrack_helper_q931;

	if (nf_ct_expect_related(exp) == 0) {
		pr_debug("nf_ct_ras: expect Q.931 ");
		nf_ct_dump_tuple(&exp->tuple);
	} else
		ret = -1;

	nf_ct_expect_put(exp);

	/* Ignore rasAddress */

	return ret;
}

/****************************************************************************/
static int process_irr(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, InfoRequestResponse *irr)
{
	int ret;
	typeof(set_ras_addr_hook) set_ras_addr;
	typeof(set_sig_addr_hook) set_sig_addr;

	pr_debug("nf_ct_ras: IRR\n");

	set_ras_addr = rcu_dereference(set_ras_addr_hook);
	if (set_ras_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		ret = set_ras_addr(skb, ct, ctinfo, protoff, data,
				   &irr->rasAddress, 1);
		if (ret < 0)
			return -1;
	}

	set_sig_addr = rcu_dereference(set_sig_addr_hook);
	if (set_sig_addr && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
	    ct->status & IPS_NAT_MASK) {
		ret = set_sig_addr(skb, ct, ctinfo, protoff, data,
					irr->callSignalAddress.item,
					irr->callSignalAddress.count);
		if (ret < 0)
			return -1;
	}

	return 0;
}

/****************************************************************************/
static int process_ras(struct sk_buff *skb, struct nf_conn *ct,
		       enum ip_conntrack_info ctinfo,
		       unsigned int protoff,
		       unsigned char **data, RasMessage *ras)
{
	switch (ras->choice) {
	case eRasMessage_gatekeeperRequest:
		return process_grq(skb, ct, ctinfo, protoff, data,
				   &ras->gatekeeperRequest);
	case eRasMessage_gatekeeperConfirm:
		return process_gcf(skb, ct, ctinfo, protoff, data,
				   &ras->gatekeeperConfirm);
	case eRasMessage_registrationRequest:
		return process_rrq(skb, ct, ctinfo, protoff, data,
				   &ras->registrationRequest);
	case eRasMessage_registrationConfirm:
		return process_rcf(skb, ct, ctinfo, protoff, data,
				   &ras->registrationConfirm);
	case eRasMessage_unregistrationRequest:
		return process_urq(skb, ct, ctinfo, protoff, data,
				   &ras->unregistrationRequest);
	case eRasMessage_admissionRequest:
		return process_arq(skb, ct, ctinfo, protoff, data,
				   &ras->admissionRequest);
	case eRasMessage_admissionConfirm:
		return process_acf(skb, ct, ctinfo, protoff, data,
				   &ras->admissionConfirm);
	case eRasMessage_locationRequest:
		return process_lrq(skb, ct, ctinfo, protoff, data,
				   &ras->locationRequest);
	case eRasMessage_locationConfirm:
		return process_lcf(skb, ct, ctinfo, protoff, data,
				   &ras->locationConfirm);
	case eRasMessage_infoRequestResponse:
		return process_irr(skb, ct, ctinfo, protoff, data,
				   &ras->infoRequestResponse);
	default:
		pr_debug("nf_ct_ras: RAS message %d\n", ras->choice);
		break;
	}

	return 0;
}

/****************************************************************************/
static int ras_help(struct sk_buff *skb, unsigned int protoff,
		    struct nf_conn *ct, enum ip_conntrack_info ctinfo)
{
	static RasMessage ras;
	unsigned char *data;
	int datalen = 0;
	int ret;

	pr_debug("nf_ct_ras: skblen = %u\n", skb->len);

	spin_lock_bh(&nf_h323_lock);

	/* Get UDP data */
	data = get_udp_data(skb, protoff, &datalen);
	if (data == NULL)
		goto accept;
	pr_debug("nf_ct_ras: RAS message len=%d ", datalen);
	nf_ct_dump_tuple(&ct->tuplehash[CTINFO2DIR(ctinfo)].tuple);

	/* Decode RAS message */
	ret = DecodeRasMessage(data, datalen, &ras);
	if (ret < 0) {
		pr_debug("nf_ct_ras: decoding error: %s\n",
			 ret == H323_ERROR_BOUND ?
			 "out of bound" : "out of range");
		goto accept;
	}

	/* Process RAS message */
	if (process_ras(skb, ct, ctinfo, protoff, &data, &ras) < 0)
		goto drop;

      accept:
	spin_unlock_bh(&nf_h323_lock);
	return NF_ACCEPT;

      drop:
	spin_unlock_bh(&nf_h323_lock);
	nf_ct_helper_log(skb, ct, "cannot process RAS message");
	return NF_DROP;
}

/****************************************************************************/
static const struct nf_conntrack_expect_policy ras_exp_policy = {
	.max_expected		= 32,
	.timeout		= 240,
};

static struct nf_conntrack_helper nf_conntrack_helper_ras[] __read_mostly = {
	{
		.name			= "RAS",
		.me			= THIS_MODULE,
		.data_len		= sizeof(struct nf_ct_h323_master),
		.tuple.src.l3num	= AF_INET,
		.tuple.src.u.udp.port	= cpu_to_be16(RAS_PORT),
		.tuple.dst.protonum	= IPPROTO_UDP,
		.help			= ras_help,
		.expect_policy		= &ras_exp_policy,
	},
	{
		.name			= "RAS",
		.me			= THIS_MODULE,
		.data_len		= sizeof(struct nf_ct_h323_master),
		.tuple.src.l3num	= AF_INET6,
		.tuple.src.u.udp.port	= cpu_to_be16(RAS_PORT),
		.tuple.dst.protonum	= IPPROTO_UDP,
		.help			= ras_help,
		.expect_policy		= &ras_exp_policy,
	},
};

/****************************************************************************/
static void __exit nf_conntrack_h323_fini(void)
{
	nf_conntrack_helper_unregister(&nf_conntrack_helper_ras[1]);
	nf_conntrack_helper_unregister(&nf_conntrack_helper_ras[0]);
	nf_conntrack_helper_unregister(&nf_conntrack_helper_q931[1]);
	nf_conntrack_helper_unregister(&nf_conntrack_helper_q931[0]);
	nf_conntrack_helper_unregister(&nf_conntrack_helper_h245);
	kfree(h323_buffer);
	pr_debug("nf_ct_h323: fini\n");
}

/****************************************************************************/
static int __init nf_conntrack_h323_init(void)
{
	int ret;

	h323_buffer = kmalloc(65536, GFP_KERNEL);
	if (!h323_buffer)
		return -ENOMEM;
	ret = nf_conntrack_helper_register(&nf_conntrack_helper_h245);
	if (ret < 0)
		goto err1;
	ret = nf_conntrack_helper_register(&nf_conntrack_helper_q931[0]);
	if (ret < 0)
		goto err2;
	ret = nf_conntrack_helper_register(&nf_conntrack_helper_q931[1]);
	if (ret < 0)
		goto err3;
	ret = nf_conntrack_helper_register(&nf_conntrack_helper_ras[0]);
	if (ret < 0)
		goto err4;
	ret = nf_conntrack_helper_register(&nf_conntrack_helper_ras[1]);
	if (ret < 0)
		goto err5;
	pr_debug("nf_ct_h323: init success\n");
	return 0;

err5:
	nf_conntrack_helper_unregister(&nf_conntrack_helper_ras[0]);
err4:
	nf_conntrack_helper_unregister(&nf_conntrack_helper_q931[1]);
err3:
	nf_conntrack_helper_unregister(&nf_conntrack_helper_q931[0]);
err2:
	nf_conntrack_helper_unregister(&nf_conntrack_helper_h245);
err1:
	kfree(h323_buffer);
	return ret;
}

/****************************************************************************/
module_init(nf_conntrack_h323_init);
module_exit(nf_conntrack_h323_fini);

EXPORT_SYMBOL_GPL(get_h225_addr);
EXPORT_SYMBOL_GPL(set_h245_addr_hook);
EXPORT_SYMBOL_GPL(set_h225_addr_hook);
EXPORT_SYMBOL_GPL(set_sig_addr_hook);
EXPORT_SYMBOL_GPL(set_ras_addr_hook);
EXPORT_SYMBOL_GPL(nat_rtp_rtcp_hook);
EXPORT_SYMBOL_GPL(nat_t120_hook);
EXPORT_SYMBOL_GPL(nat_h245_hook);
EXPORT_SYMBOL_GPL(nat_callforwarding_hook);
EXPORT_SYMBOL_GPL(nat_q931_hook);

MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
MODULE_DESCRIPTION("H.323 connection tracking helper");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_conntrack_h323");
MODULE_ALIAS_NFCT_HELPER("RAS");
MODULE_ALIAS_NFCT_HELPER("Q.931");
MODULE_ALIAS_NFCT_HELPER("H.245");