nf_nat_h323.c

linux 内核源代码

			printk("nf_nat_h323: out of TCP ports\n");
		return 0;
	}

	/* Modify signal */
	if (set_h245_addr(skb, data, dataoff, taddr,
			  &ct->tuplehash[!dir].tuple.dst.u3,
			  htons(nated_port)) < 0) {
		nf_ct_unexpect_related(exp);
		return -1;
	}

	pr_debug("nf_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
		 NIPQUAD(exp->tuple.src.u3.ip),
		 ntohs(exp->tuple.src.u.tcp.port),
		 NIPQUAD(exp->tuple.dst.u3.ip),
		 ntohs(exp->tuple.dst.u.tcp.port));

	return 0;
}

/****************************************************************************/
static int nat_h245(struct sk_buff *skb, 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_ct_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(skb, 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_ct_unexpect_related(exp);
		return -1;
	}

	pr_debug("nf_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
		 NIPQUAD(exp->tuple.src.u3.ip),
		 ntohs(exp->tuple.src.u.tcp.port),
		 NIPQUAD(exp->tuple.dst.u3.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 nf_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 *skb, 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_ct_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(skb, 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(skb, data, 0, &taddr[0],
				      &ct->tuplehash[!dir].tuple.dst.u3,
				      info->sig_port[!dir]);
		}
	} else {
		nf_ct_unexpect_related(exp);
		return -1;
	}

	/* Success */
	pr_debug("nf_nat_ras: expect Q.931 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
		 NIPQUAD(exp->tuple.src.u3.ip),
		 ntohs(exp->tuple.src.u.tcp.port),
		 NIPQUAD(exp->tuple.dst.u3.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 *skb, 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_ct_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(skb, data, dataoff, taddr,
			   &ct->tuplehash[!dir].tuple.dst.u3,
			   htons(nated_port)) == 0) {
		nf_ct_unexpect_related(exp);
		return -1;
	}

	/* Success */
	pr_debug("nf_nat_q931: expect Call Forwarding "
		 "%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
		 NIPQUAD(exp->tuple.src.u3.ip),
		 ntohs(exp->tuple.src.u.tcp.port),
		 NIPQUAD(exp->tuple.dst.u3.ip),
		 ntohs(exp->tuple.dst.u.tcp.port));

	return 0;
}

/****************************************************************************/
static int __init init(void)
{
	BUG_ON(set_h245_addr_hook != NULL);
	BUG_ON(set_h225_addr_hook != NULL);
	BUG_ON(set_sig_addr_hook != NULL);
	BUG_ON(set_ras_addr_hook != NULL);
	BUG_ON(nat_rtp_rtcp_hook != NULL);
	BUG_ON(nat_t120_hook != NULL);
	BUG_ON(nat_h245_hook != NULL);
	BUG_ON(nat_callforwarding_hook != NULL);
	BUG_ON(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);
	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 <[e-mail]>");
MODULE_DESCRIPTION("H.323 NAT helper");
MODULE_LICENSE("GPL");
MODULE_ALIAS("ip_nat_h323");