[PATCH 15/25] netfilter: nf_nat: support IPv6 in SIP NAT helper

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From: Patrick McHardy <kaber@xxxxxxxxx>

Add IPv6 support to the SIP NAT helper. There are no functional differences
to IPv4 NAT, just different formats for addresses.

Signed-off-by: Patrick McHardy <kaber@xxxxxxxxx>
---
 include/linux/netfilter/nf_conntrack_sip.h |    9 +-
 net/ipv4/netfilter/Kconfig                 |    5 -
 net/ipv4/netfilter/Makefile                |    1 -
 net/ipv4/netfilter/nf_nat_sip.c            |  580 --------------------------
 net/netfilter/Kconfig                      |    5 +
 net/netfilter/Makefile                     |    1 +
 net/netfilter/nf_conntrack_sip.c           |   68 ++--
 net/netfilter/nf_nat_sip.c                 |  609 ++++++++++++++++++++++++++++
 8 files changed, 653 insertions(+), 625 deletions(-)
 delete mode 100644 net/ipv4/netfilter/nf_nat_sip.c
 create mode 100644 net/netfilter/nf_nat_sip.c

diff --git a/include/linux/netfilter/nf_conntrack_sip.h b/include/linux/netfilter/nf_conntrack_sip.h
index 1afc669..387bdd0 100644
--- a/include/linux/netfilter/nf_conntrack_sip.h
+++ b/include/linux/netfilter/nf_conntrack_sip.h
@@ -99,10 +99,8 @@ enum sip_header_types {
 enum sdp_header_types {
 	SDP_HDR_UNSPEC,
 	SDP_HDR_VERSION,
-	SDP_HDR_OWNER_IP4,
-	SDP_HDR_CONNECTION_IP4,
-	SDP_HDR_OWNER_IP6,
-	SDP_HDR_CONNECTION_IP6,
+	SDP_HDR_OWNER,
+	SDP_HDR_CONNECTION,
 	SDP_HDR_MEDIA,
 };
 
@@ -111,7 +109,8 @@ extern unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb,
 				       unsigned int dataoff,
 				       const char **dptr,
 				       unsigned int *datalen);
-extern void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, s16 off);
+extern void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb,
+					  unsigned int protoff, s16 off);
 extern unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
 					      unsigned int protoff,
 					      unsigned int dataoff,
diff --git a/net/ipv4/netfilter/Kconfig b/net/ipv4/netfilter/Kconfig
index 52c4a87..30197f8 100644
--- a/net/ipv4/netfilter/Kconfig
+++ b/net/ipv4/netfilter/Kconfig
@@ -242,11 +242,6 @@ config NF_NAT_H323
 	depends on NF_CONNTRACK && NF_NAT_IPV4
 	default NF_NAT_IPV4 && NF_CONNTRACK_H323
 
-config NF_NAT_SIP
-	tristate
-	depends on NF_CONNTRACK && NF_NAT_IPV4
-	default NF_NAT_IPV4 && NF_CONNTRACK_SIP
-
 # mangle + specific targets
 config IP_NF_MANGLE
 	tristate "Packet mangling"
diff --git a/net/ipv4/netfilter/Makefile b/net/ipv4/netfilter/Makefile
index 8baa496..8914abf 100644
--- a/net/ipv4/netfilter/Makefile
+++ b/net/ipv4/netfilter/Makefile
@@ -23,7 +23,6 @@ obj-$(CONFIG_NF_DEFRAG_IPV4) += nf_defrag_ipv4.o
 obj-$(CONFIG_NF_NAT_H323) += nf_nat_h323.o
 obj-$(CONFIG_NF_NAT_IRC) += nf_nat_irc.o
 obj-$(CONFIG_NF_NAT_PPTP) += nf_nat_pptp.o
-obj-$(CONFIG_NF_NAT_SIP) += nf_nat_sip.o
 obj-$(CONFIG_NF_NAT_SNMP_BASIC) += nf_nat_snmp_basic.o
 obj-$(CONFIG_NF_NAT_TFTP) += nf_nat_tftp.o
 
diff --git a/net/ipv4/netfilter/nf_nat_sip.c b/net/ipv4/netfilter/nf_nat_sip.c
deleted file mode 100644
index 47a4718..0000000
--- a/net/ipv4/netfilter/nf_nat_sip.c
+++ /dev/null
@@ -1,580 +0,0 @@
-/* SIP extension for NAT alteration.
- *
- * (C) 2005 by Christian Hentschel <chentschel@xxxxxxxxxxxx>
- * based on RR's ip_nat_ftp.c and other modules.
- * (C) 2007 United Security Providers
- * (C) 2007, 2008 Patrick McHardy <kaber@xxxxxxxxx>
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 as
- * published by the Free Software Foundation.
- */
-
-#include <linux/module.h>
-#include <linux/skbuff.h>
-#include <linux/ip.h>
-#include <net/ip.h>
-#include <linux/udp.h>
-#include <linux/tcp.h>
-
-#include <net/netfilter/nf_nat.h>
-#include <net/netfilter/nf_nat_helper.h>
-#include <net/netfilter/nf_conntrack_helper.h>
-#include <net/netfilter/nf_conntrack_expect.h>
-#include <linux/netfilter/nf_conntrack_sip.h>
-
-MODULE_LICENSE("GPL");
-MODULE_AUTHOR("Christian Hentschel <chentschel@xxxxxxxxxxxx>");
-MODULE_DESCRIPTION("SIP NAT helper");
-MODULE_ALIAS("ip_nat_sip");
-
-
-static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff,
-				  unsigned int dataoff,
-				  const char **dptr, unsigned int *datalen,
-				  unsigned int matchoff, unsigned int matchlen,
-				  const char *buffer, unsigned int buflen)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	struct tcphdr *th;
-	unsigned int baseoff;
-
-	if (nf_ct_protonum(ct) == IPPROTO_TCP) {
-		th = (struct tcphdr *)(skb->data + ip_hdrlen(skb));
-		baseoff = ip_hdrlen(skb) + th->doff * 4;
-		matchoff += dataoff - baseoff;
-
-		if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
-						protoff, matchoff, matchlen,
-						buffer, buflen, false))
-			return 0;
-	} else {
-		baseoff = ip_hdrlen(skb) + sizeof(struct udphdr);
-		matchoff += dataoff - baseoff;
-
-		if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
-					      protoff, matchoff, matchlen,
-					      buffer, buflen))
-			return 0;
-	}
-
-	/* Reload data pointer and adjust datalen value */
-	*dptr = skb->data + dataoff;
-	*datalen += buflen - matchlen;
-	return 1;
-}
-
-static int map_addr(struct sk_buff *skb, unsigned int protoff,
-		    unsigned int dataoff,
-		    const char **dptr, unsigned int *datalen,
-		    unsigned int matchoff, unsigned int matchlen,
-		    union nf_inet_addr *addr, __be16 port)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
-	unsigned int buflen;
-	__be32 newaddr;
-	__be16 newport;
-
-	if (ct->tuplehash[dir].tuple.src.u3.ip == addr->ip &&
-	    ct->tuplehash[dir].tuple.src.u.udp.port == port) {
-		newaddr = ct->tuplehash[!dir].tuple.dst.u3.ip;
-		newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
-	} else if (ct->tuplehash[dir].tuple.dst.u3.ip == addr->ip &&
-		   ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
-		newaddr = ct->tuplehash[!dir].tuple.src.u3.ip;
-		newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
-	} else
-		return 1;
-
-	if (newaddr == addr->ip && newport == port)
-		return 1;
-
-	buflen = sprintf(buffer, "%pI4:%u", &newaddr, ntohs(newport));
-
-	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
-			     matchoff, matchlen, buffer, buflen);
-}
-
-static int map_sip_addr(struct sk_buff *skb, unsigned int protoff,
-			unsigned int dataoff,
-			const char **dptr, unsigned int *datalen,
-			enum sip_header_types type)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchlen, matchoff;
-	union nf_inet_addr addr;
-	__be16 port;
-
-	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL,
-				    &matchoff, &matchlen, &addr, &port) <= 0)
-		return 1;
-	return map_addr(skb, protoff, dataoff, dptr, datalen,
-			matchoff, matchlen, &addr, port);
-}
-
-static unsigned int ip_nat_sip(struct sk_buff *skb, unsigned int protoff,
-			       unsigned int dataoff,
-			       const char **dptr, unsigned int *datalen)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	unsigned int coff, matchoff, matchlen;
-	enum sip_header_types hdr;
-	union nf_inet_addr addr;
-	__be16 port;
-	int request, in_header;
-
-	/* Basic rules: requests and responses. */
-	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
-		if (ct_sip_parse_request(ct, *dptr, *datalen,
-					 &matchoff, &matchlen,
-					 &addr, &port) > 0 &&
-		    !map_addr(skb, protoff, dataoff, dptr, datalen,
-			      matchoff, matchlen, &addr, port))
-			return NF_DROP;
-		request = 1;
-	} else
-		request = 0;
-
-	if (nf_ct_protonum(ct) == IPPROTO_TCP)
-		hdr = SIP_HDR_VIA_TCP;
-	else
-		hdr = SIP_HDR_VIA_UDP;
-
-	/* Translate topmost Via header and parameters */
-	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
-				    hdr, NULL, &matchoff, &matchlen,
-				    &addr, &port) > 0) {
-		unsigned int olen, matchend, poff, plen, buflen, n;
-		char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
-
-		/* We're only interested in headers related to this
-		 * connection */
-		if (request) {
-			if (addr.ip != ct->tuplehash[dir].tuple.src.u3.ip ||
-			    port != ct->tuplehash[dir].tuple.src.u.udp.port)
-				goto next;
-		} else {
-			if (addr.ip != ct->tuplehash[dir].tuple.dst.u3.ip ||
-			    port != ct->tuplehash[dir].tuple.dst.u.udp.port)
-				goto next;
-		}
-
-		olen = *datalen;
-		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
-			      matchoff, matchlen, &addr, port))
-			return NF_DROP;
-
-		matchend = matchoff + matchlen + *datalen - olen;
-
-		/* The maddr= parameter (RFC 2361) specifies where to send
-		 * the reply. */
-		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
-					       "maddr=", &poff, &plen,
-					       &addr, true) > 0 &&
-		    addr.ip == ct->tuplehash[dir].tuple.src.u3.ip &&
-		    addr.ip != ct->tuplehash[!dir].tuple.dst.u3.ip) {
-			buflen = sprintf(buffer, "%pI4",
-					&ct->tuplehash[!dir].tuple.dst.u3.ip);
-			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-					   poff, plen, buffer, buflen))
-				return NF_DROP;
-		}
-
-		/* The received= parameter (RFC 2361) contains the address
-		 * from which the server received the request. */
-		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
-					       "received=", &poff, &plen,
-					       &addr, false) > 0 &&
-		    addr.ip == ct->tuplehash[dir].tuple.dst.u3.ip &&
-		    addr.ip != ct->tuplehash[!dir].tuple.src.u3.ip) {
-			buflen = sprintf(buffer, "%pI4",
-					&ct->tuplehash[!dir].tuple.src.u3.ip);
-			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-					   poff, plen, buffer, buflen))
-				return NF_DROP;
-		}
-
-		/* The rport= parameter (RFC 3581) contains the port number
-		 * from which the server received the request. */
-		if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
-						 "rport=", &poff, &plen,
-						 &n) > 0 &&
-		    htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
-		    htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
-			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
-			buflen = sprintf(buffer, "%u", ntohs(p));
-			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-					   poff, plen, buffer, buflen))
-				return NF_DROP;
-		}
-	}
-
-next:
-	/* Translate Contact headers */
-	coff = 0;
-	in_header = 0;
-	while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
-				       SIP_HDR_CONTACT, &in_header,
-				       &matchoff, &matchlen,
-				       &addr, &port) > 0) {
-		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
-			      matchoff, matchlen,
-			      &addr, port))
-			return NF_DROP;
-	}
-
-	if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||
-	    !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO))
-		return NF_DROP;
-
-	return NF_ACCEPT;
-}
-
-static void ip_nat_sip_seq_adjust(struct sk_buff *skb, s16 off)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	const struct tcphdr *th;
-
-	if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0)
-		return;
-
-	th = (struct tcphdr *)(skb->data + ip_hdrlen(skb));
-	nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off);
-}
-
-/* Handles expected signalling connections and media streams */
-static void ip_nat_sip_expected(struct nf_conn *ct,
-				struct nf_conntrack_expect *exp)
-{
-	struct nf_nat_range range;
-
-	/* This must be a fresh one. */
-	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
-
-	/* For DST manip, map port here to where it's expected. */
-	range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
-	range.min_proto = range.max_proto = exp->saved_proto;
-	range.min_addr = range.max_addr = exp->saved_addr;
-	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
-
-	/* Change src to where master sends to, but only if the connection
-	 * actually came from the same source. */
-	if (ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip ==
-	    ct->master->tuplehash[exp->dir].tuple.src.u3.ip) {
-		range.flags = NF_NAT_RANGE_MAP_IPS;
-		range.min_addr = range.max_addr
-			= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
-		nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
-	}
-}
-
-static unsigned int ip_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,
-				      unsigned int dataoff,
-				      const char **dptr, unsigned int *datalen,
-				      struct nf_conntrack_expect *exp,
-				      unsigned int matchoff,
-				      unsigned int matchlen)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	__be32 newip;
-	u_int16_t port;
-	char buffer[sizeof("nnn.nnn.nnn.nnn:nnnnn")];
-	unsigned int buflen;
-
-	/* Connection will come from reply */
-	if (ct->tuplehash[dir].tuple.src.u3.ip == ct->tuplehash[!dir].tuple.dst.u3.ip)
-		newip = exp->tuple.dst.u3.ip;
-	else
-		newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
-
-	/* If the signalling port matches the connection's source port in the
-	 * original direction, try to use the destination port in the opposite
-	 * direction. */
-	if (exp->tuple.dst.u.udp.port ==
-	    ct->tuplehash[dir].tuple.src.u.udp.port)
-		port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
-	else
-		port = ntohs(exp->tuple.dst.u.udp.port);
-
-	exp->saved_addr = exp->tuple.dst.u3;
-	exp->tuple.dst.u3.ip = newip;
-	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
-	exp->dir = !dir;
-	exp->expectfn = ip_nat_sip_expected;
-
-	for (; port != 0; port++) {
-		int ret;
-
-		exp->tuple.dst.u.udp.port = htons(port);
-		ret = nf_ct_expect_related(exp);
-		if (ret == 0)
-			break;
-		else if (ret != -EBUSY) {
-			port = 0;
-			break;
-		}
-	}
-
-	if (port == 0)
-		return NF_DROP;
-
-	if (exp->tuple.dst.u3.ip != exp->saved_addr.ip ||
-	    exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
-		buflen = sprintf(buffer, "%pI4:%u", &newip, port);
-		if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-				   matchoff, matchlen, buffer, buflen))
-			goto err;
-	}
-	return NF_ACCEPT;
-
-err:
-	nf_ct_unexpect_related(exp);
-	return NF_DROP;
-}
-
-static int mangle_content_len(struct sk_buff *skb, unsigned int protoff,
-			      unsigned int dataoff,
-			      const char **dptr, unsigned int *datalen)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchoff, matchlen;
-	char buffer[sizeof("65536")];
-	int buflen, c_len;
-
-	/* Get actual SDP length */
-	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
-				  SDP_HDR_VERSION, SDP_HDR_UNSPEC,
-				  &matchoff, &matchlen) <= 0)
-		return 0;
-	c_len = *datalen - matchoff + strlen("v=");
-
-	/* Now, update SDP length */
-	if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
-			      &matchoff, &matchlen) <= 0)
-		return 0;
-
-	buflen = sprintf(buffer, "%u", c_len);
-	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
-			     matchoff, matchlen, buffer, buflen);
-}
-
-static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff,
-			     unsigned int dataoff,
-			     const char **dptr, unsigned int *datalen,
-			     unsigned int sdpoff,
-			     enum sdp_header_types type,
-			     enum sdp_header_types term,
-			     char *buffer, int buflen)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	unsigned int matchlen, matchoff;
-
-	if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term,
-				  &matchoff, &matchlen) <= 0)
-		return -ENOENT;
-	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
-			     matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL;
-}
-
-static unsigned int ip_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff,
-				    unsigned int dataoff,
-				    const char **dptr, unsigned int *datalen,
-				    unsigned int sdpoff,
-				    enum sdp_header_types type,
-				    enum sdp_header_types term,
-				    const union nf_inet_addr *addr)
-{
-	char buffer[sizeof("nnn.nnn.nnn.nnn")];
-	unsigned int buflen;
-
-	buflen = sprintf(buffer, "%pI4", &addr->ip);
-	if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen,
-			      sdpoff, type, term, buffer, buflen))
-		return 0;
-
-	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
-}
-
-static unsigned int ip_nat_sdp_port(struct sk_buff *skb, unsigned int protoff,
-				    unsigned int dataoff,
-				    const char **dptr, unsigned int *datalen,
-				    unsigned int matchoff,
-				    unsigned int matchlen,
-				    u_int16_t port)
-{
-	char buffer[sizeof("nnnnn")];
-	unsigned int buflen;
-
-	buflen = sprintf(buffer, "%u", port);
-	if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
-			   matchoff, matchlen, buffer, buflen))
-		return 0;
-
-	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
-}
-
-static unsigned int ip_nat_sdp_session(struct sk_buff *skb, unsigned int protoff,
-				       unsigned int dataoff,
-				       const char **dptr, unsigned int *datalen,
-				       unsigned int sdpoff,
-				       const union nf_inet_addr *addr)
-{
-	char buffer[sizeof("nnn.nnn.nnn.nnn")];
-	unsigned int buflen;
-
-	/* Mangle session description owner and contact addresses */
-	buflen = sprintf(buffer, "%pI4", &addr->ip);
-	if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
-			       SDP_HDR_OWNER_IP4, SDP_HDR_MEDIA,
-			       buffer, buflen))
-		return 0;
-
-	switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
-				  SDP_HDR_CONNECTION_IP4, SDP_HDR_MEDIA,
-				  buffer, buflen)) {
-	case 0:
-	/*
-	 * RFC 2327:
-	 *
-	 * Session description
-	 *
-	 * c=* (connection information - not required if included in all media)
-	 */
-	case -ENOENT:
-		break;
-	default:
-		return 0;
-	}
-
-	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
-}
-
-/* So, this packet has hit the connection tracking matching code.
-   Mangle it, and change the expectation to match the new version. */
-static unsigned int ip_nat_sdp_media(struct sk_buff *skb, unsigned int protoff,
-				     unsigned int dataoff,
-				     const char **dptr, unsigned int *datalen,
-				     struct nf_conntrack_expect *rtp_exp,
-				     struct nf_conntrack_expect *rtcp_exp,
-				     unsigned int mediaoff,
-				     unsigned int medialen,
-				     union nf_inet_addr *rtp_addr)
-{
-	enum ip_conntrack_info ctinfo;
-	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
-	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
-	u_int16_t port;
-
-	/* Connection will come from reply */
-	if (ct->tuplehash[dir].tuple.src.u3.ip ==
-	    ct->tuplehash[!dir].tuple.dst.u3.ip)
-		rtp_addr->ip = rtp_exp->tuple.dst.u3.ip;
-	else
-		rtp_addr->ip = ct->tuplehash[!dir].tuple.dst.u3.ip;
-
-	rtp_exp->saved_addr = rtp_exp->tuple.dst.u3;
-	rtp_exp->tuple.dst.u3.ip = rtp_addr->ip;
-	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
-	rtp_exp->dir = !dir;
-	rtp_exp->expectfn = ip_nat_sip_expected;
-
-	rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3;
-	rtcp_exp->tuple.dst.u3.ip = rtp_addr->ip;
-	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
-	rtcp_exp->dir = !dir;
-	rtcp_exp->expectfn = ip_nat_sip_expected;
-
-	/* Try to get same pair of ports: if not, try to change them. */
-	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
-	     port != 0; port += 2) {
-		int ret;
-
-		rtp_exp->tuple.dst.u.udp.port = htons(port);
-		ret = nf_ct_expect_related(rtp_exp);
-		if (ret == -EBUSY)
-			continue;
-		else if (ret < 0) {
-			port = 0;
-			break;
-		}
-		rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
-		ret = nf_ct_expect_related(rtcp_exp);
-		if (ret == 0)
-			break;
-		else if (ret != -EBUSY) {
-			nf_ct_unexpect_related(rtp_exp);
-			port = 0;
-			break;
-		}
-	}
-
-	if (port == 0)
-		goto err1;
-
-	/* Update media port. */
-	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
-	    !ip_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
-			     mediaoff, medialen, port))
-		goto err2;
-
-	return NF_ACCEPT;
-
-err2:
-	nf_ct_unexpect_related(rtp_exp);
-	nf_ct_unexpect_related(rtcp_exp);
-err1:
-	return NF_DROP;
-}
-
-static struct nf_ct_helper_expectfn sip_nat = {
-        .name           = "sip",
-        .expectfn       = ip_nat_sip_expected,
-};
-
-static void __exit nf_nat_sip_fini(void)
-{
-	RCU_INIT_POINTER(nf_nat_sip_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sip_expect_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL);
-	RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL);
-	nf_ct_helper_expectfn_unregister(&sip_nat);
-	synchronize_rcu();
-}
-
-static int __init nf_nat_sip_init(void)
-{
-	BUG_ON(nf_nat_sip_hook != NULL);
-	BUG_ON(nf_nat_sip_seq_adjust_hook != NULL);
-	BUG_ON(nf_nat_sip_expect_hook != NULL);
-	BUG_ON(nf_nat_sdp_addr_hook != NULL);
-	BUG_ON(nf_nat_sdp_port_hook != NULL);
-	BUG_ON(nf_nat_sdp_session_hook != NULL);
-	BUG_ON(nf_nat_sdp_media_hook != NULL);
-	RCU_INIT_POINTER(nf_nat_sip_hook, ip_nat_sip);
-	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, ip_nat_sip_seq_adjust);
-	RCU_INIT_POINTER(nf_nat_sip_expect_hook, ip_nat_sip_expect);
-	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, ip_nat_sdp_addr);
-	RCU_INIT_POINTER(nf_nat_sdp_port_hook, ip_nat_sdp_port);
-	RCU_INIT_POINTER(nf_nat_sdp_session_hook, ip_nat_sdp_session);
-	RCU_INIT_POINTER(nf_nat_sdp_media_hook, ip_nat_sdp_media);
-	nf_ct_helper_expectfn_register(&sip_nat);
-	return 0;
-}
-
-module_init(nf_nat_sip_init);
-module_exit(nf_nat_sip_fini);
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index 2eee9f1..bf3e464 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -390,6 +390,11 @@ config NF_NAT_FTP
 	depends on NF_CONNTRACK && NF_NAT
 	default NF_NAT && NF_CONNTRACK_FTP
 
+config NF_NAT_SIP
+	tristate
+	depends on NF_CONNTRACK && NF_NAT
+	default NF_NAT && NF_CONNTRACK_SIP
+
 endif # NF_CONNTRACK
 
 # transparent proxy support
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index 7d6e1ea..7d6d1a0 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -57,6 +57,7 @@ obj-$(CONFIG_NF_NAT_PROTO_SCTP) += nf_nat_proto_sctp.o
 # NAT helpers
 obj-$(CONFIG_NF_NAT_AMANDA) += nf_nat_amanda.o
 obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o
+obj-$(CONFIG_NF_NAT_SIP) += nf_nat_sip.o
 
 # transparent proxy support
 obj-$(CONFIG_NETFILTER_TPROXY) += nf_tproxy_core.o
diff --git a/net/netfilter/nf_conntrack_sip.c b/net/netfilter/nf_conntrack_sip.c
index d517490..df8f4f2 100644
--- a/net/netfilter/nf_conntrack_sip.c
+++ b/net/netfilter/nf_conntrack_sip.c
@@ -57,7 +57,8 @@ unsigned int (*nf_nat_sip_hook)(struct sk_buff *skb, unsigned int protoff,
 				unsigned int *datalen) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sip_hook);
 
-void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, s16 off) __read_mostly;
+void (*nf_nat_sip_seq_adjust_hook)(struct sk_buff *skb, unsigned int protoff,
+				   s16 off) __read_mostly;
 EXPORT_SYMBOL_GPL(nf_nat_sip_seq_adjust_hook);
 
 unsigned int (*nf_nat_sip_expect_hook)(struct sk_buff *skb,
@@ -742,13 +743,18 @@ static int sdp_addr_len(const struct nf_conn *ct, const char *dptr,
  * be tolerant and also accept records terminated with a single newline
  * character". We handle both cases.
  */
-static const struct sip_header ct_sdp_hdrs[] = {
-	[SDP_HDR_VERSION]		= SDP_HDR("v=", NULL, digits_len),
-	[SDP_HDR_OWNER_IP4]		= SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
-	[SDP_HDR_CONNECTION_IP4]	= SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
-	[SDP_HDR_OWNER_IP6]		= SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
-	[SDP_HDR_CONNECTION_IP6]	= SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
-	[SDP_HDR_MEDIA]			= SDP_HDR("m=", NULL, media_len),
+static const struct sip_header ct_sdp_hdrs_v4[] = {
+	[SDP_HDR_VERSION]	= SDP_HDR("v=", NULL, digits_len),
+	[SDP_HDR_OWNER]		= SDP_HDR("o=", "IN IP4 ", sdp_addr_len),
+	[SDP_HDR_CONNECTION]	= SDP_HDR("c=", "IN IP4 ", sdp_addr_len),
+	[SDP_HDR_MEDIA]		= SDP_HDR("m=", NULL, media_len),
+};
+
+static const struct sip_header ct_sdp_hdrs_v6[] = {
+	[SDP_HDR_VERSION]	= SDP_HDR("v=", NULL, digits_len),
+	[SDP_HDR_OWNER]		= SDP_HDR("o=", "IN IP6 ", sdp_addr_len),
+	[SDP_HDR_CONNECTION]	= SDP_HDR("c=", "IN IP6 ", sdp_addr_len),
+	[SDP_HDR_MEDIA]		= SDP_HDR("m=", NULL, media_len),
 };
 
 /* Linear string search within SDP header values */
@@ -774,11 +780,14 @@ int ct_sip_get_sdp_header(const struct nf_conn *ct, const char *dptr,
 			  enum sdp_header_types term,
 			  unsigned int *matchoff, unsigned int *matchlen)
 {
-	const struct sip_header *hdr = &ct_sdp_hdrs[type];
-	const struct sip_header *thdr = &ct_sdp_hdrs[term];
+	const struct sip_header *hdrs, *hdr, *thdr;
 	const char *start = dptr, *limit = dptr + datalen;
 	int shift = 0;
 
+	hdrs = nf_ct_l3num(ct) == NFPROTO_IPV4 ? ct_sdp_hdrs_v4 : ct_sdp_hdrs_v6;
+	hdr = &hdrs[type];
+	thdr = &hdrs[term];
+
 	for (dptr += dataoff; dptr < limit; dptr++) {
 		/* Find beginning of line */
 		if (*dptr != '\r' && *dptr != '\n')
@@ -945,12 +954,12 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
 		    exp->class != class)
 			break;
 #ifdef CONFIG_NF_NAT_NEEDED
-		if (exp->tuple.src.l3num == AF_INET && !direct_rtp &&
-		    (exp->saved_addr.ip != exp->tuple.dst.u3.ip ||
+		if (!direct_rtp &&
+		    (!nf_inet_addr_cmp(&exp->saved_addr, &exp->tuple.dst.u3) ||
 		     exp->saved_proto.udp.port != exp->tuple.dst.u.udp.port) &&
 		    ct->status & IPS_NAT_MASK) {
-			daddr->ip		= exp->saved_addr.ip;
-			tuple.dst.u3.ip		= exp->saved_addr.ip;
+			*daddr			= exp->saved_addr;
+			tuple.dst.u3		= exp->saved_addr;
 			tuple.dst.u.udp.port	= exp->saved_proto.udp.port;
 			direct_rtp = 1;
 		} else
@@ -987,8 +996,7 @@ static int set_expected_rtp_rtcp(struct sk_buff *skb, unsigned int protoff,
 			  IPPROTO_UDP, NULL, &rtcp_port);
 
 	nf_nat_sdp_media = rcu_dereference(nf_nat_sdp_media_hook);
-	if (nf_nat_sdp_media && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
-	    ct->status & IPS_NAT_MASK && !direct_rtp)
+	if (nf_nat_sdp_media && ct->status & IPS_NAT_MASK && !direct_rtp)
 		ret = nf_nat_sdp_media(skb, protoff, dataoff, dptr, datalen,
 				       rtp_exp, rtcp_exp,
 				       mediaoff, medialen, daddr);
@@ -1044,15 +1052,12 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 	unsigned int i;
 	union nf_inet_addr caddr, maddr, rtp_addr;
 	unsigned int port;
-	enum sdp_header_types c_hdr;
 	const struct sdp_media_type *t;
 	int ret = NF_ACCEPT;
 	typeof(nf_nat_sdp_addr_hook) nf_nat_sdp_addr;
 	typeof(nf_nat_sdp_session_hook) nf_nat_sdp_session;
 
 	nf_nat_sdp_addr = rcu_dereference(nf_nat_sdp_addr_hook);
-	c_hdr = nf_ct_l3num(ct) == AF_INET ? SDP_HDR_CONNECTION_IP4 :
-					     SDP_HDR_CONNECTION_IP6;
 
 	/* Find beginning of session description */
 	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
@@ -1066,7 +1071,7 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 	 * the end of the session description. */
 	caddr_len = 0;
 	if (ct_sip_parse_sdp_addr(ct, *dptr, sdpoff, *datalen,
-				  c_hdr, SDP_HDR_MEDIA,
+				  SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
 				  &matchoff, &matchlen, &caddr) > 0)
 		caddr_len = matchlen;
 
@@ -1096,7 +1101,7 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 		/* The media description overrides the session description. */
 		maddr_len = 0;
 		if (ct_sip_parse_sdp_addr(ct, *dptr, mediaoff, *datalen,
-					  c_hdr, SDP_HDR_MEDIA,
+					  SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
 					  &matchoff, &matchlen, &maddr) > 0) {
 			maddr_len = matchlen;
 			memcpy(&rtp_addr, &maddr, sizeof(rtp_addr));
@@ -1113,11 +1118,10 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 			return ret;
 
 		/* Update media connection address if present */
-		if (maddr_len && nf_nat_sdp_addr &&
-		    nf_ct_l3num(ct) == NFPROTO_IPV4 && ct->status & IPS_NAT_MASK) {
+		if (maddr_len && nf_nat_sdp_addr && ct->status & IPS_NAT_MASK) {
 			ret = nf_nat_sdp_addr(skb, protoff, dataoff,
-					      dptr, datalen,
-					      mediaoff, c_hdr, SDP_HDR_MEDIA,
+					      dptr, datalen, mediaoff,
+					      SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
 					      &rtp_addr);
 			if (ret != NF_ACCEPT)
 				return ret;
@@ -1127,8 +1131,7 @@ static int process_sdp(struct sk_buff *skb, unsigned int protoff,
 
 	/* Update session connection and owner addresses */
 	nf_nat_sdp_session = rcu_dereference(nf_nat_sdp_session_hook);
-	if (nf_nat_sdp_session && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
-	    ct->status & IPS_NAT_MASK)
+	if (nf_nat_sdp_session && ct->status & IPS_NAT_MASK)
 		ret = nf_nat_sdp_session(skb, protoff, dataoff,
 					 dptr, datalen, sdpoff, &rtp_addr);
 
@@ -1293,8 +1296,7 @@ static int process_register_request(struct sk_buff *skb, unsigned int protoff,
 	exp->flags = NF_CT_EXPECT_PERMANENT | NF_CT_EXPECT_INACTIVE;
 
 	nf_nat_sip_expect = rcu_dereference(nf_nat_sip_expect_hook);
-	if (nf_nat_sip_expect && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
-	    ct->status & IPS_NAT_MASK)
+	if (nf_nat_sip_expect && ct->status & IPS_NAT_MASK)
 		ret = nf_nat_sip_expect(skb, protoff, dataoff, dptr, datalen,
 					exp, matchoff, matchlen);
 	else {
@@ -1476,8 +1478,7 @@ static int process_sip_msg(struct sk_buff *skb, struct nf_conn *ct,
 	else
 		ret = process_sip_response(skb, protoff, dataoff, dptr, datalen);
 
-	if (ret == NF_ACCEPT && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
-	    ct->status & IPS_NAT_MASK) {
+	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
 		nf_nat_sip = rcu_dereference(nf_nat_sip_hook);
 		if (nf_nat_sip && !nf_nat_sip(skb, protoff, dataoff,
 					      dptr, datalen))
@@ -1560,11 +1561,10 @@ static int sip_help_tcp(struct sk_buff *skb, unsigned int protoff,
 		datalen  = datalen + diff - msglen;
 	}
 
-	if (ret == NF_ACCEPT && nf_ct_l3num(ct) == NFPROTO_IPV4 &&
-	    ct->status & IPS_NAT_MASK) {
+	if (ret == NF_ACCEPT && ct->status & IPS_NAT_MASK) {
 		nf_nat_sip_seq_adjust = rcu_dereference(nf_nat_sip_seq_adjust_hook);
 		if (nf_nat_sip_seq_adjust)
-			nf_nat_sip_seq_adjust(skb, tdiff);
+			nf_nat_sip_seq_adjust(skb, protoff, tdiff);
 	}
 
 	return ret;
diff --git a/net/netfilter/nf_nat_sip.c b/net/netfilter/nf_nat_sip.c
new file mode 100644
index 0000000..f4db3a7
--- /dev/null
+++ b/net/netfilter/nf_nat_sip.c
@@ -0,0 +1,609 @@
+/* SIP extension for NAT alteration.
+ *
+ * (C) 2005 by Christian Hentschel <chentschel@xxxxxxxxxxxx>
+ * based on RR's ip_nat_ftp.c and other modules.
+ * (C) 2007 United Security Providers
+ * (C) 2007, 2008, 2011, 2012 Patrick McHardy <kaber@xxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/inet.h>
+#include <linux/udp.h>
+#include <linux/tcp.h>
+
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_sip.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Christian Hentschel <chentschel@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("SIP NAT helper");
+MODULE_ALIAS("ip_nat_sip");
+
+
+static unsigned int mangle_packet(struct sk_buff *skb, unsigned int protoff,
+				  unsigned int dataoff,
+				  const char **dptr, unsigned int *datalen,
+				  unsigned int matchoff, unsigned int matchlen,
+				  const char *buffer, unsigned int buflen)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	struct tcphdr *th;
+	unsigned int baseoff;
+
+	if (nf_ct_protonum(ct) == IPPROTO_TCP) {
+		th = (struct tcphdr *)(skb->data + protoff);
+		baseoff = protoff + th->doff * 4;
+		matchoff += dataoff - baseoff;
+
+		if (!__nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
+						protoff, matchoff, matchlen,
+						buffer, buflen, false))
+			return 0;
+	} else {
+		baseoff = protoff + sizeof(struct udphdr);
+		matchoff += dataoff - baseoff;
+
+		if (!nf_nat_mangle_udp_packet(skb, ct, ctinfo,
+					      protoff, matchoff, matchlen,
+					      buffer, buflen))
+			return 0;
+	}
+
+	/* Reload data pointer and adjust datalen value */
+	*dptr = skb->data + dataoff;
+	*datalen += buflen - matchlen;
+	return 1;
+}
+
+static int sip_sprintf_addr(const struct nf_conn *ct, char *buffer,
+			    const union nf_inet_addr *addr, bool delim)
+{
+	if (nf_ct_l3num(ct) == NFPROTO_IPV4)
+		return sprintf(buffer, "%pI4", &addr->ip);
+	else {
+		if (delim)
+			return sprintf(buffer, "[%pI6c]", &addr->ip6);
+		else
+			return sprintf(buffer, "%pI6c", &addr->ip6);
+	}
+}
+
+static int sip_sprintf_addr_port(const struct nf_conn *ct, char *buffer,
+				 const union nf_inet_addr *addr, u16 port)
+{
+	if (nf_ct_l3num(ct) == NFPROTO_IPV4)
+		return sprintf(buffer, "%pI4:%u", &addr->ip, port);
+	else
+		return sprintf(buffer, "[%pI6c]:%u", &addr->ip6, port);
+}
+
+static int map_addr(struct sk_buff *skb, unsigned int protoff,
+		    unsigned int dataoff,
+		    const char **dptr, unsigned int *datalen,
+		    unsigned int matchoff, unsigned int matchlen,
+		    union nf_inet_addr *addr, __be16 port)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
+	unsigned int buflen;
+	union nf_inet_addr newaddr;
+	__be16 newport;
+
+	if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3, addr) &&
+	    ct->tuplehash[dir].tuple.src.u.udp.port == port) {
+		newaddr = ct->tuplehash[!dir].tuple.dst.u3;
+		newport = ct->tuplehash[!dir].tuple.dst.u.udp.port;
+	} else if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.dst.u3, addr) &&
+		   ct->tuplehash[dir].tuple.dst.u.udp.port == port) {
+		newaddr = ct->tuplehash[!dir].tuple.src.u3;
+		newport = ct->tuplehash[!dir].tuple.src.u.udp.port;
+	} else
+		return 1;
+
+	if (nf_inet_addr_cmp(&newaddr, addr) && newport == port)
+		return 1;
+
+	buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, ntohs(newport));
+	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
+			     matchoff, matchlen, buffer, buflen);
+}
+
+static int map_sip_addr(struct sk_buff *skb, unsigned int protoff,
+			unsigned int dataoff,
+			const char **dptr, unsigned int *datalen,
+			enum sip_header_types type)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	unsigned int matchlen, matchoff;
+	union nf_inet_addr addr;
+	__be16 port;
+
+	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen, type, NULL,
+				    &matchoff, &matchlen, &addr, &port) <= 0)
+		return 1;
+	return map_addr(skb, protoff, dataoff, dptr, datalen,
+			matchoff, matchlen, &addr, port);
+}
+
+static unsigned int nf_nat_sip(struct sk_buff *skb, unsigned int protoff,
+			       unsigned int dataoff,
+			       const char **dptr, unsigned int *datalen)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	unsigned int coff, matchoff, matchlen;
+	enum sip_header_types hdr;
+	union nf_inet_addr addr;
+	__be16 port;
+	int request, in_header;
+
+	/* Basic rules: requests and responses. */
+	if (strnicmp(*dptr, "SIP/2.0", strlen("SIP/2.0")) != 0) {
+		if (ct_sip_parse_request(ct, *dptr, *datalen,
+					 &matchoff, &matchlen,
+					 &addr, &port) > 0 &&
+		    !map_addr(skb, protoff, dataoff, dptr, datalen,
+			      matchoff, matchlen, &addr, port))
+			return NF_DROP;
+		request = 1;
+	} else
+		request = 0;
+
+	if (nf_ct_protonum(ct) == IPPROTO_TCP)
+		hdr = SIP_HDR_VIA_TCP;
+	else
+		hdr = SIP_HDR_VIA_UDP;
+
+	/* Translate topmost Via header and parameters */
+	if (ct_sip_parse_header_uri(ct, *dptr, NULL, *datalen,
+				    hdr, NULL, &matchoff, &matchlen,
+				    &addr, &port) > 0) {
+		unsigned int olen, matchend, poff, plen, buflen, n;
+		char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
+
+		/* We're only interested in headers related to this
+		 * connection */
+		if (request) {
+			if (!nf_inet_addr_cmp(&addr,
+					&ct->tuplehash[dir].tuple.src.u3) ||
+			    port != ct->tuplehash[dir].tuple.src.u.udp.port)
+				goto next;
+		} else {
+			if (!nf_inet_addr_cmp(&addr,
+					&ct->tuplehash[dir].tuple.dst.u3) ||
+			    port != ct->tuplehash[dir].tuple.dst.u.udp.port)
+				goto next;
+		}
+
+		olen = *datalen;
+		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
+			      matchoff, matchlen, &addr, port))
+			return NF_DROP;
+
+		matchend = matchoff + matchlen + *datalen - olen;
+
+		/* The maddr= parameter (RFC 2361) specifies where to send
+		 * the reply. */
+		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
+					       "maddr=", &poff, &plen,
+					       &addr, true) > 0 &&
+		    nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.src.u3) &&
+		    !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.dst.u3)) {
+			buflen = sip_sprintf_addr(ct, buffer,
+					&ct->tuplehash[!dir].tuple.dst.u3,
+					true);
+			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
+					   poff, plen, buffer, buflen))
+				return NF_DROP;
+		}
+
+		/* The received= parameter (RFC 2361) contains the address
+		 * from which the server received the request. */
+		if (ct_sip_parse_address_param(ct, *dptr, matchend, *datalen,
+					       "received=", &poff, &plen,
+					       &addr, false) > 0 &&
+		    nf_inet_addr_cmp(&addr, &ct->tuplehash[dir].tuple.dst.u3) &&
+		    !nf_inet_addr_cmp(&addr, &ct->tuplehash[!dir].tuple.src.u3)) {
+			buflen = sip_sprintf_addr(ct, buffer,
+					&ct->tuplehash[!dir].tuple.src.u3,
+					false);
+			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
+					   poff, plen, buffer, buflen))
+				return NF_DROP;
+		}
+
+		/* The rport= parameter (RFC 3581) contains the port number
+		 * from which the server received the request. */
+		if (ct_sip_parse_numerical_param(ct, *dptr, matchend, *datalen,
+						 "rport=", &poff, &plen,
+						 &n) > 0 &&
+		    htons(n) == ct->tuplehash[dir].tuple.dst.u.udp.port &&
+		    htons(n) != ct->tuplehash[!dir].tuple.src.u.udp.port) {
+			__be16 p = ct->tuplehash[!dir].tuple.src.u.udp.port;
+			buflen = sprintf(buffer, "%u", ntohs(p));
+			if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
+					   poff, plen, buffer, buflen))
+				return NF_DROP;
+		}
+	}
+
+next:
+	/* Translate Contact headers */
+	coff = 0;
+	in_header = 0;
+	while (ct_sip_parse_header_uri(ct, *dptr, &coff, *datalen,
+				       SIP_HDR_CONTACT, &in_header,
+				       &matchoff, &matchlen,
+				       &addr, &port) > 0) {
+		if (!map_addr(skb, protoff, dataoff, dptr, datalen,
+			      matchoff, matchlen,
+			      &addr, port))
+			return NF_DROP;
+	}
+
+	if (!map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_FROM) ||
+	    !map_sip_addr(skb, protoff, dataoff, dptr, datalen, SIP_HDR_TO))
+		return NF_DROP;
+
+	return NF_ACCEPT;
+}
+
+static void nf_nat_sip_seq_adjust(struct sk_buff *skb, unsigned int protoff,
+				  s16 off)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	const struct tcphdr *th;
+
+	if (nf_ct_protonum(ct) != IPPROTO_TCP || off == 0)
+		return;
+
+	th = (struct tcphdr *)(skb->data + protoff);
+	nf_nat_set_seq_adjust(ct, ctinfo, th->seq, off);
+}
+
+/* Handles expected signalling connections and media streams */
+static void nf_nat_sip_expected(struct nf_conn *ct,
+				struct nf_conntrack_expect *exp)
+{
+	struct nf_nat_range range;
+
+	/* This must be a fresh one. */
+	BUG_ON(ct->status & IPS_NAT_DONE_MASK);
+
+	/* For DST manip, map port here to where it's expected. */
+	range.flags = (NF_NAT_RANGE_MAP_IPS | NF_NAT_RANGE_PROTO_SPECIFIED);
+	range.min_proto = range.max_proto = exp->saved_proto;
+	range.min_addr = range.max_addr = exp->saved_addr;
+	nf_nat_setup_info(ct, &range, NF_NAT_MANIP_DST);
+
+	/* Change src to where master sends to, but only if the connection
+	 * actually came from the same source. */
+	if (nf_inet_addr_cmp(&ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3,
+			     &ct->master->tuplehash[exp->dir].tuple.src.u3)) {
+		range.flags = NF_NAT_RANGE_MAP_IPS;
+		range.min_addr = range.max_addr
+			= ct->master->tuplehash[!exp->dir].tuple.dst.u3;
+		nf_nat_setup_info(ct, &range, NF_NAT_MANIP_SRC);
+	}
+}
+
+static unsigned int nf_nat_sip_expect(struct sk_buff *skb, unsigned int protoff,
+				      unsigned int dataoff,
+				      const char **dptr, unsigned int *datalen,
+				      struct nf_conntrack_expect *exp,
+				      unsigned int matchoff,
+				      unsigned int matchlen)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	union nf_inet_addr newaddr;
+	u_int16_t port;
+	char buffer[INET6_ADDRSTRLEN + sizeof("[]:nnnnn")];
+	unsigned int buflen;
+
+	/* Connection will come from reply */
+	if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
+			     &ct->tuplehash[!dir].tuple.dst.u3))
+		newaddr = exp->tuple.dst.u3;
+	else
+		newaddr = ct->tuplehash[!dir].tuple.dst.u3;
+
+	/* If the signalling port matches the connection's source port in the
+	 * original direction, try to use the destination port in the opposite
+	 * direction. */
+	if (exp->tuple.dst.u.udp.port ==
+	    ct->tuplehash[dir].tuple.src.u.udp.port)
+		port = ntohs(ct->tuplehash[!dir].tuple.dst.u.udp.port);
+	else
+		port = ntohs(exp->tuple.dst.u.udp.port);
+
+	exp->saved_addr = exp->tuple.dst.u3;
+	exp->tuple.dst.u3 = newaddr;
+	exp->saved_proto.udp.port = exp->tuple.dst.u.udp.port;
+	exp->dir = !dir;
+	exp->expectfn = nf_nat_sip_expected;
+
+	for (; port != 0; port++) {
+		int ret;
+
+		exp->tuple.dst.u.udp.port = htons(port);
+		ret = nf_ct_expect_related(exp);
+		if (ret == 0)
+			break;
+		else if (ret != -EBUSY) {
+			port = 0;
+			break;
+		}
+	}
+
+	if (port == 0)
+		return NF_DROP;
+
+	if (!nf_inet_addr_cmp(&exp->tuple.dst.u3, &exp->saved_addr) ||
+	    exp->tuple.dst.u.udp.port != exp->saved_proto.udp.port) {
+		buflen = sip_sprintf_addr_port(ct, buffer, &newaddr, port);
+		if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
+				   matchoff, matchlen, buffer, buflen))
+			goto err;
+	}
+	return NF_ACCEPT;
+
+err:
+	nf_ct_unexpect_related(exp);
+	return NF_DROP;
+}
+
+static int mangle_content_len(struct sk_buff *skb, unsigned int protoff,
+			      unsigned int dataoff,
+			      const char **dptr, unsigned int *datalen)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	unsigned int matchoff, matchlen;
+	char buffer[sizeof("65536")];
+	int buflen, c_len;
+
+	/* Get actual SDP length */
+	if (ct_sip_get_sdp_header(ct, *dptr, 0, *datalen,
+				  SDP_HDR_VERSION, SDP_HDR_UNSPEC,
+				  &matchoff, &matchlen) <= 0)
+		return 0;
+	c_len = *datalen - matchoff + strlen("v=");
+
+	/* Now, update SDP length */
+	if (ct_sip_get_header(ct, *dptr, 0, *datalen, SIP_HDR_CONTENT_LENGTH,
+			      &matchoff, &matchlen) <= 0)
+		return 0;
+
+	buflen = sprintf(buffer, "%u", c_len);
+	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
+			     matchoff, matchlen, buffer, buflen);
+}
+
+static int mangle_sdp_packet(struct sk_buff *skb, unsigned int protoff,
+			     unsigned int dataoff,
+			     const char **dptr, unsigned int *datalen,
+			     unsigned int sdpoff,
+			     enum sdp_header_types type,
+			     enum sdp_header_types term,
+			     char *buffer, int buflen)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	unsigned int matchlen, matchoff;
+
+	if (ct_sip_get_sdp_header(ct, *dptr, sdpoff, *datalen, type, term,
+				  &matchoff, &matchlen) <= 0)
+		return -ENOENT;
+	return mangle_packet(skb, protoff, dataoff, dptr, datalen,
+			     matchoff, matchlen, buffer, buflen) ? 0 : -EINVAL;
+}
+
+static unsigned int nf_nat_sdp_addr(struct sk_buff *skb, unsigned int protoff,
+				    unsigned int dataoff,
+				    const char **dptr, unsigned int *datalen,
+				    unsigned int sdpoff,
+				    enum sdp_header_types type,
+				    enum sdp_header_types term,
+				    const union nf_inet_addr *addr)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	char buffer[INET6_ADDRSTRLEN];
+	unsigned int buflen;
+
+	buflen = sip_sprintf_addr(ct, buffer, addr, false);
+	if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen,
+			      sdpoff, type, term, buffer, buflen))
+		return 0;
+
+	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
+}
+
+static unsigned int nf_nat_sdp_port(struct sk_buff *skb, unsigned int protoff,
+				    unsigned int dataoff,
+				    const char **dptr, unsigned int *datalen,
+				    unsigned int matchoff,
+				    unsigned int matchlen,
+				    u_int16_t port)
+{
+	char buffer[sizeof("nnnnn")];
+	unsigned int buflen;
+
+	buflen = sprintf(buffer, "%u", port);
+	if (!mangle_packet(skb, protoff, dataoff, dptr, datalen,
+			   matchoff, matchlen, buffer, buflen))
+		return 0;
+
+	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
+}
+
+static unsigned int nf_nat_sdp_session(struct sk_buff *skb, unsigned int protoff,
+				       unsigned int dataoff,
+				       const char **dptr, unsigned int *datalen,
+				       unsigned int sdpoff,
+				       const union nf_inet_addr *addr)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	char buffer[INET6_ADDRSTRLEN];
+	unsigned int buflen;
+
+	/* Mangle session description owner and contact addresses */
+	buflen = sip_sprintf_addr(ct, buffer, addr, false);
+	if (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
+			      SDP_HDR_OWNER, SDP_HDR_MEDIA, buffer, buflen))
+		return 0;
+
+	switch (mangle_sdp_packet(skb, protoff, dataoff, dptr, datalen, sdpoff,
+				  SDP_HDR_CONNECTION, SDP_HDR_MEDIA,
+				  buffer, buflen)) {
+	case 0:
+	/*
+	 * RFC 2327:
+	 *
+	 * Session description
+	 *
+	 * c=* (connection information - not required if included in all media)
+	 */
+	case -ENOENT:
+		break;
+	default:
+		return 0;
+	}
+
+	return mangle_content_len(skb, protoff, dataoff, dptr, datalen);
+}
+
+/* So, this packet has hit the connection tracking matching code.
+   Mangle it, and change the expectation to match the new version. */
+static unsigned int nf_nat_sdp_media(struct sk_buff *skb, unsigned int protoff,
+				     unsigned int dataoff,
+				     const char **dptr, unsigned int *datalen,
+				     struct nf_conntrack_expect *rtp_exp,
+				     struct nf_conntrack_expect *rtcp_exp,
+				     unsigned int mediaoff,
+				     unsigned int medialen,
+				     union nf_inet_addr *rtp_addr)
+{
+	enum ip_conntrack_info ctinfo;
+	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
+	enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
+	u_int16_t port;
+
+	/* Connection will come from reply */
+	if (nf_inet_addr_cmp(&ct->tuplehash[dir].tuple.src.u3,
+			     &ct->tuplehash[!dir].tuple.dst.u3))
+		*rtp_addr = rtp_exp->tuple.dst.u3;
+	else
+		*rtp_addr = ct->tuplehash[!dir].tuple.dst.u3;
+
+	rtp_exp->saved_addr = rtp_exp->tuple.dst.u3;
+	rtp_exp->tuple.dst.u3 = *rtp_addr;
+	rtp_exp->saved_proto.udp.port = rtp_exp->tuple.dst.u.udp.port;
+	rtp_exp->dir = !dir;
+	rtp_exp->expectfn = nf_nat_sip_expected;
+
+	rtcp_exp->saved_addr = rtcp_exp->tuple.dst.u3;
+	rtcp_exp->tuple.dst.u3 = *rtp_addr;
+	rtcp_exp->saved_proto.udp.port = rtcp_exp->tuple.dst.u.udp.port;
+	rtcp_exp->dir = !dir;
+	rtcp_exp->expectfn = nf_nat_sip_expected;
+
+	/* Try to get same pair of ports: if not, try to change them. */
+	for (port = ntohs(rtp_exp->tuple.dst.u.udp.port);
+	     port != 0; port += 2) {
+		int ret;
+
+		rtp_exp->tuple.dst.u.udp.port = htons(port);
+		ret = nf_ct_expect_related(rtp_exp);
+		if (ret == -EBUSY)
+			continue;
+		else if (ret < 0) {
+			port = 0;
+			break;
+		}
+		rtcp_exp->tuple.dst.u.udp.port = htons(port + 1);
+		ret = nf_ct_expect_related(rtcp_exp);
+		if (ret == 0)
+			break;
+		else if (ret != -EBUSY) {
+			nf_ct_unexpect_related(rtp_exp);
+			port = 0;
+			break;
+		}
+	}
+
+	if (port == 0)
+		goto err1;
+
+	/* Update media port. */
+	if (rtp_exp->tuple.dst.u.udp.port != rtp_exp->saved_proto.udp.port &&
+	    !nf_nat_sdp_port(skb, protoff, dataoff, dptr, datalen,
+			     mediaoff, medialen, port))
+		goto err2;
+
+	return NF_ACCEPT;
+
+err2:
+	nf_ct_unexpect_related(rtp_exp);
+	nf_ct_unexpect_related(rtcp_exp);
+err1:
+	return NF_DROP;
+}
+
+static struct nf_ct_helper_expectfn sip_nat = {
+	.name		= "sip",
+	.expectfn	= nf_nat_sip_expected,
+};
+
+static void __exit nf_nat_sip_fini(void)
+{
+	RCU_INIT_POINTER(nf_nat_sip_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sip_expect_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sdp_port_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sdp_session_hook, NULL);
+	RCU_INIT_POINTER(nf_nat_sdp_media_hook, NULL);
+	nf_ct_helper_expectfn_unregister(&sip_nat);
+	synchronize_rcu();
+}
+
+static int __init nf_nat_sip_init(void)
+{
+	BUG_ON(nf_nat_sip_hook != NULL);
+	BUG_ON(nf_nat_sip_seq_adjust_hook != NULL);
+	BUG_ON(nf_nat_sip_expect_hook != NULL);
+	BUG_ON(nf_nat_sdp_addr_hook != NULL);
+	BUG_ON(nf_nat_sdp_port_hook != NULL);
+	BUG_ON(nf_nat_sdp_session_hook != NULL);
+	BUG_ON(nf_nat_sdp_media_hook != NULL);
+	RCU_INIT_POINTER(nf_nat_sip_hook, nf_nat_sip);
+	RCU_INIT_POINTER(nf_nat_sip_seq_adjust_hook, nf_nat_sip_seq_adjust);
+	RCU_INIT_POINTER(nf_nat_sip_expect_hook, nf_nat_sip_expect);
+	RCU_INIT_POINTER(nf_nat_sdp_addr_hook, nf_nat_sdp_addr);
+	RCU_INIT_POINTER(nf_nat_sdp_port_hook, nf_nat_sdp_port);
+	RCU_INIT_POINTER(nf_nat_sdp_session_hook, nf_nat_sdp_session);
+	RCU_INIT_POINTER(nf_nat_sdp_media_hook, nf_nat_sdp_media);
+	nf_ct_helper_expectfn_register(&sip_nat);
+	return 0;
+}
+
+module_init(nf_nat_sip_init);
+module_exit(nf_nat_sip_fini);
-- 
1.7.10.4

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