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![Patrick McHardy](/assets/img/avatar_default.png)
Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
534 lines
16 KiB
C
534 lines
16 KiB
C
/*
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* H.323 extension for NAT alteration.
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*
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* Copyright (c) 2006 Jing Min Zhao <zhaojingmin@users.sourceforge.net>
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*
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* This source code is licensed under General Public License version 2.
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*
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* Based on the 'brute force' H.323 NAT module by
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* Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
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*/
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#include <linux/module.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/netfilter.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/moduleparam.h>
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#include <net/tcp.h>
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/netfilter_ipv4/ip_conntrack_tuple.h>
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#include <linux/netfilter_ipv4/ip_conntrack_h323.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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/****************************************************************************/
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static int set_addr(struct sk_buff **pskb,
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unsigned char **data, int dataoff,
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unsigned int addroff, u_int32_t ip, u_int16_t port)
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{
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enum ip_conntrack_info ctinfo;
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struct ip_conntrack *ct = ip_conntrack_get(*pskb, &ctinfo);
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struct {
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u_int32_t ip;
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u_int16_t port;
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} __attribute__ ((__packed__)) buf;
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struct tcphdr _tcph, *th;
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buf.ip = ip;
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buf.port = htons(port);
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addroff += dataoff;
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if ((*pskb)->nh.iph->protocol == IPPROTO_TCP) {
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if (!ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
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addroff, sizeof(buf),
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(char *) &buf, sizeof(buf))) {
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if (net_ratelimit())
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printk("ip_nat_h323: ip_nat_mangle_tcp_packet"
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" error\n");
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return -1;
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}
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/* Relocate data pointer */
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th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl * 4,
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sizeof(_tcph), &_tcph);
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if (th == NULL)
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return -1;
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*data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
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th->doff * 4 + dataoff;
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} else {
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if (!ip_nat_mangle_udp_packet(pskb, ct, ctinfo,
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addroff, sizeof(buf),
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(char *) &buf, sizeof(buf))) {
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if (net_ratelimit())
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printk("ip_nat_h323: ip_nat_mangle_udp_packet"
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" error\n");
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return -1;
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}
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/* ip_nat_mangle_udp_packet uses skb_make_writable() to copy
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* or pull everything in a linear buffer, so we can safely
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* use the skb pointers now */
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*data = (*pskb)->data + (*pskb)->nh.iph->ihl * 4 +
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sizeof(struct udphdr);
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}
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return 0;
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}
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/****************************************************************************/
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static int set_h225_addr(struct sk_buff **pskb,
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unsigned char **data, int dataoff,
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TransportAddress * addr,
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u_int32_t ip, u_int16_t port)
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{
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return set_addr(pskb, data, dataoff, addr->ipAddress.ip, ip, port);
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}
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/****************************************************************************/
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static int set_h245_addr(struct sk_buff **pskb,
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unsigned char **data, int dataoff,
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H245_TransportAddress * addr,
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u_int32_t ip, u_int16_t port)
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{
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return set_addr(pskb, data, dataoff,
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addr->unicastAddress.iPAddress.network, ip, port);
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}
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/****************************************************************************/
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static int set_sig_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data,
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TransportAddress * addr, int count)
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{
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struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
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int dir = CTINFO2DIR(ctinfo);
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int i;
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u_int32_t ip;
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u_int16_t port;
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for (i = 0; i < count; i++) {
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if (get_h225_addr(*data, &addr[i], &ip, &port)) {
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if (ip == ct->tuplehash[dir].tuple.src.ip &&
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port == info->sig_port[dir]) {
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/* GW->GK */
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/* Fix for Gnomemeeting */
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if (i > 0 &&
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get_h225_addr(*data, &addr[0],
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&ip, &port) &&
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(ntohl(ip) & 0xff000000) == 0x7f000000)
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i = 0;
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DEBUGP
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("ip_nat_ras: set signal address "
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"%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(ip), port,
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NIPQUAD(ct->tuplehash[!dir].tuple.dst.
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ip), info->sig_port[!dir]);
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return set_h225_addr(pskb, data, 0, &addr[i],
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ct->tuplehash[!dir].
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tuple.dst.ip,
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info->sig_port[!dir]);
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} else if (ip == ct->tuplehash[dir].tuple.dst.ip &&
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port == info->sig_port[dir]) {
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/* GK->GW */
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DEBUGP
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("ip_nat_ras: set signal address "
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"%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(ip), port,
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NIPQUAD(ct->tuplehash[!dir].tuple.src.
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ip), info->sig_port[!dir]);
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return set_h225_addr(pskb, data, 0, &addr[i],
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ct->tuplehash[!dir].
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tuple.src.ip,
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info->sig_port[!dir]);
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}
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}
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}
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return 0;
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}
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/****************************************************************************/
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static int set_ras_addr(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data,
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TransportAddress * addr, int count)
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{
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int dir = CTINFO2DIR(ctinfo);
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int i;
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u_int32_t ip;
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u_int16_t port;
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for (i = 0; i < count; i++) {
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if (get_h225_addr(*data, &addr[i], &ip, &port) &&
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ip == ct->tuplehash[dir].tuple.src.ip &&
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port == ntohs(ct->tuplehash[dir].tuple.src.u.udp.port)) {
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DEBUGP("ip_nat_ras: set rasAddress "
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"%u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(ip), port,
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NIPQUAD(ct->tuplehash[!dir].tuple.dst.ip),
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ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.
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port));
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return set_h225_addr(pskb, data, 0, &addr[i],
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ct->tuplehash[!dir].tuple.dst.ip,
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ntohs(ct->tuplehash[!dir].tuple.
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dst.u.udp.port));
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}
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}
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return 0;
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}
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/****************************************************************************/
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static int nat_rtp_rtcp(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data, int dataoff,
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H245_TransportAddress * addr,
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u_int16_t port, u_int16_t rtp_port,
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struct ip_conntrack_expect *rtp_exp,
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struct ip_conntrack_expect *rtcp_exp)
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{
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struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
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int dir = CTINFO2DIR(ctinfo);
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int i;
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u_int16_t nated_port;
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/* Set expectations for NAT */
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rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
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rtp_exp->expectfn = ip_nat_follow_master;
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rtp_exp->dir = !dir;
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rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
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rtcp_exp->expectfn = ip_nat_follow_master;
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rtcp_exp->dir = !dir;
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/* Lookup existing expects */
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for (i = 0; i < H323_RTP_CHANNEL_MAX; i++) {
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if (info->rtp_port[i][dir] == rtp_port) {
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/* Expected */
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/* Use allocated ports first. This will refresh
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* the expects */
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rtp_exp->tuple.dst.u.udp.port =
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htons(info->rtp_port[i][dir]);
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rtcp_exp->tuple.dst.u.udp.port =
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htons(info->rtp_port[i][dir] + 1);
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break;
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} else if (info->rtp_port[i][dir] == 0) {
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/* Not expected */
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break;
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}
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}
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/* Run out of expectations */
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if (i >= H323_RTP_CHANNEL_MAX) {
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if (net_ratelimit())
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printk("ip_nat_h323: out of expectations\n");
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return 0;
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}
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/* Try to get a pair of ports. */
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for (nated_port = ntohs(rtp_exp->tuple.dst.u.udp.port);
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nated_port != 0; nated_port += 2) {
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rtp_exp->tuple.dst.u.udp.port = htons(nated_port);
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if (ip_conntrack_expect_related(rtp_exp) == 0) {
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rtcp_exp->tuple.dst.u.udp.port =
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htons(nated_port + 1);
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if (ip_conntrack_expect_related(rtcp_exp) == 0)
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break;
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ip_conntrack_unexpect_related(rtp_exp);
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}
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}
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if (nated_port == 0) { /* No port available */
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if (net_ratelimit())
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printk("ip_nat_h323: out of RTP ports\n");
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return 0;
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}
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/* Modify signal */
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if (set_h245_addr(pskb, data, dataoff, addr,
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ct->tuplehash[!dir].tuple.dst.ip,
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(port & 1) ? nated_port + 1 : nated_port) == 0) {
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/* Save ports */
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info->rtp_port[i][dir] = rtp_port;
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info->rtp_port[i][!dir] = nated_port;
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} else {
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ip_conntrack_unexpect_related(rtp_exp);
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ip_conntrack_unexpect_related(rtcp_exp);
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return -1;
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}
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/* Success */
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DEBUGP("ip_nat_h323: expect RTP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(rtp_exp->tuple.src.ip),
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ntohs(rtp_exp->tuple.src.u.udp.port),
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NIPQUAD(rtp_exp->tuple.dst.ip),
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ntohs(rtp_exp->tuple.dst.u.udp.port));
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DEBUGP("ip_nat_h323: expect RTCP %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(rtcp_exp->tuple.src.ip),
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ntohs(rtcp_exp->tuple.src.u.udp.port),
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NIPQUAD(rtcp_exp->tuple.dst.ip),
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ntohs(rtcp_exp->tuple.dst.u.udp.port));
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return 0;
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}
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/****************************************************************************/
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static int nat_t120(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data, int dataoff,
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H245_TransportAddress * addr, u_int16_t port,
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struct ip_conntrack_expect *exp)
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{
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int dir = CTINFO2DIR(ctinfo);
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u_int16_t nated_port = port;
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/* Set expectations for NAT */
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exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
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exp->expectfn = ip_nat_follow_master;
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exp->dir = !dir;
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/* Try to get same port: if not, try to change it. */
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for (; nated_port != 0; nated_port++) {
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exp->tuple.dst.u.tcp.port = htons(nated_port);
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if (ip_conntrack_expect_related(exp) == 0)
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break;
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}
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if (nated_port == 0) { /* No port available */
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if (net_ratelimit())
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printk("ip_nat_h323: out of TCP ports\n");
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return 0;
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}
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/* Modify signal */
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if (set_h245_addr(pskb, data, dataoff, addr,
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ct->tuplehash[!dir].tuple.dst.ip, nated_port) < 0) {
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ip_conntrack_unexpect_related(exp);
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return -1;
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}
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DEBUGP("ip_nat_h323: expect T.120 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
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NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
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return 0;
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}
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/****************************************************************************
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* This conntrack expect function replaces ip_conntrack_h245_expect()
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* which was set by ip_conntrack_helper_h323.c. It calls both
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* ip_nat_follow_master() and ip_conntrack_h245_expect()
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****************************************************************************/
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static void ip_nat_h245_expect(struct ip_conntrack *new,
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struct ip_conntrack_expect *this)
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{
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ip_nat_follow_master(new, this);
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ip_conntrack_h245_expect(new, this);
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}
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/****************************************************************************/
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static int nat_h245(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data, int dataoff,
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TransportAddress * addr, u_int16_t port,
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struct ip_conntrack_expect *exp)
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{
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struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
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int dir = CTINFO2DIR(ctinfo);
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u_int16_t nated_port = port;
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/* Set expectations for NAT */
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exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
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exp->expectfn = ip_nat_h245_expect;
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exp->dir = !dir;
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/* Check existing expects */
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if (info->sig_port[dir] == port)
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nated_port = info->sig_port[!dir];
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/* Try to get same port: if not, try to change it. */
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for (; nated_port != 0; nated_port++) {
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exp->tuple.dst.u.tcp.port = htons(nated_port);
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if (ip_conntrack_expect_related(exp) == 0)
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break;
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}
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if (nated_port == 0) { /* No port available */
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if (net_ratelimit())
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printk("ip_nat_q931: out of TCP ports\n");
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return 0;
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}
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/* Modify signal */
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if (set_h225_addr(pskb, data, dataoff, addr,
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ct->tuplehash[!dir].tuple.dst.ip,
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nated_port) == 0) {
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/* Save ports */
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info->sig_port[dir] = port;
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info->sig_port[!dir] = nated_port;
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} else {
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ip_conntrack_unexpect_related(exp);
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return -1;
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}
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DEBUGP("ip_nat_q931: expect H.245 %u.%u.%u.%u:%hu->%u.%u.%u.%u:%hu\n",
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NIPQUAD(exp->tuple.src.ip), ntohs(exp->tuple.src.u.tcp.port),
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NIPQUAD(exp->tuple.dst.ip), ntohs(exp->tuple.dst.u.tcp.port));
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return 0;
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}
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/****************************************************************************
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* This conntrack expect function replaces ip_conntrack_q931_expect()
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* which was set by ip_conntrack_helper_h323.c.
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****************************************************************************/
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static void ip_nat_q931_expect(struct ip_conntrack *new,
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struct ip_conntrack_expect *this)
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{
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struct ip_nat_range range;
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if (this->tuple.src.ip != 0) { /* Only accept calls from GK */
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ip_nat_follow_master(new, this);
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goto out;
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}
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/* This must be a fresh one. */
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BUG_ON(new->status & IPS_NAT_DONE_MASK);
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/* Change src to where master sends to */
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range.flags = IP_NAT_RANGE_MAP_IPS;
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range.min_ip = range.max_ip = new->tuplehash[!this->dir].tuple.src.ip;
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/* hook doesn't matter, but it has to do source manip */
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ip_nat_setup_info(new, &range, NF_IP_POST_ROUTING);
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/* For DST manip, map port here to where it's expected. */
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range.flags = (IP_NAT_RANGE_MAP_IPS | IP_NAT_RANGE_PROTO_SPECIFIED);
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range.min = range.max = this->saved_proto;
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range.min_ip = range.max_ip =
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new->master->tuplehash[!this->dir].tuple.src.ip;
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/* hook doesn't matter, but it has to do destination manip */
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ip_nat_setup_info(new, &range, NF_IP_PRE_ROUTING);
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out:
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ip_conntrack_q931_expect(new, this);
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}
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/****************************************************************************/
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static int nat_q931(struct sk_buff **pskb, struct ip_conntrack *ct,
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enum ip_conntrack_info ctinfo,
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unsigned char **data, TransportAddress * addr, int idx,
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u_int16_t port, struct ip_conntrack_expect *exp)
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{
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struct ip_ct_h323_master *info = &ct->help.ct_h323_info;
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int dir = CTINFO2DIR(ctinfo);
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u_int16_t nated_port = port;
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u_int32_t ip;
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/* Set expectations for NAT */
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exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
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exp->expectfn = ip_nat_q931_expect;
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exp->dir = !dir;
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/* Check existing expects */
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if (info->sig_port[dir] == port)
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nated_port = info->sig_port[!dir];
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/* Try to get same port: if not, try to change it. */
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for (; nated_port != 0; nated_port++) {
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exp->tuple.dst.u.tcp.port = htons(nated_port);
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if (ip_conntrack_expect_related(exp) == 0)
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break;
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}
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if (nated_port == 0) { /* No port available */
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|
if (net_ratelimit())
|
|
printk("ip_nat_ras: out of TCP ports\n");
|
|
return 0;
|
|
}
|
|
|
|
/* Modify signal */
|
|
if (set_h225_addr(pskb, data, 0, &addr[idx],
|
|
ct->tuplehash[!dir].tuple.dst.ip,
|
|
nated_port) == 0) {
|
|
/* Save ports */
|
|
info->sig_port[dir] = port;
|
|
info->sig_port[!dir] = nated_port;
|
|
|
|
/* Fix for Gnomemeeting */
|
|
if (idx > 0 &&
|
|
get_h225_addr(*data, &addr[0], &ip, &port) &&
|
|
(ntohl(ip) & 0xff000000) == 0x7f000000) {
|
|
set_h225_addr_hook(pskb, data, 0, &addr[0],
|
|
ct->tuplehash[!dir].tuple.dst.ip,
|
|
info->sig_port[!dir]);
|
|
}
|
|
} else {
|
|
ip_conntrack_unexpect_related(exp);
|
|
return -1;
|
|
}
|
|
|
|
/* Success */
|
|
DEBUGP("ip_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 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_q931_hook != NULL);
|
|
|
|
set_h245_addr_hook = set_h245_addr;
|
|
set_h225_addr_hook = set_h225_addr;
|
|
set_sig_addr_hook = set_sig_addr;
|
|
set_ras_addr_hook = set_ras_addr;
|
|
nat_rtp_rtcp_hook = nat_rtp_rtcp;
|
|
nat_t120_hook = nat_t120;
|
|
nat_h245_hook = nat_h245;
|
|
nat_q931_hook = nat_q931;
|
|
|
|
DEBUGP("ip_nat_h323: init success\n");
|
|
return 0;
|
|
}
|
|
|
|
/****************************************************************************/
|
|
static void __exit fini(void)
|
|
{
|
|
set_h245_addr_hook = NULL;
|
|
set_h225_addr_hook = NULL;
|
|
set_sig_addr_hook = NULL;
|
|
set_ras_addr_hook = NULL;
|
|
nat_rtp_rtcp_hook = NULL;
|
|
nat_t120_hook = NULL;
|
|
nat_h245_hook = NULL;
|
|
nat_q931_hook = NULL;
|
|
synchronize_net();
|
|
}
|
|
|
|
/****************************************************************************/
|
|
module_init(init);
|
|
module_exit(fini);
|
|
|
|
MODULE_AUTHOR("Jing Min Zhao <zhaojingmin@users.sourceforge.net>");
|
|
MODULE_DESCRIPTION("H.323 NAT helper");
|
|
MODULE_LICENSE("GPL");
|