Ok, after finding out rather late that the rtsp patch did not work with 2.6.22, I downloaded 2.6.23-rc2 and ported it yet again. As always you can find the code here. I really hope that this patch will survive 2.6.23-final.
NB: As always, this code works for me, if you find any bugs or have fixes please contact me.
Discussion
i have used your two rtsp's patches and notice they don't work with mythtv (on freebox in france). I can't change url (channel in this case) since i have opened one first.
The last patche i know to work is this one for 2.6.19.2 :
diff -Naur linux-2.6.19.2/include/linux/netfilter_ipv4/ip_conntrack_rtsp.h linux-2.6.19.2-rtsp/include/linux/netfilter_ipv4/ip_conntrack_rtsp.h
--- linux-2.6.19.2/include/linux/netfilter_ipv4/ip_conntrack_rtsp.h 1970-01-01 01:00:00.000000000 0100
linux-2.6.19.2-rtsp/include/linux/netfilter_ipv4/ip_conntrack_rtsp.h 2007-01-27 18:18:35.000000000 0100
@@ -0,0 1,60 @@
/*
* RTSP extension for IP connection tracking.
* (C) 2003 by Tom Marshall <tmarshall@real.com>
* based on ip_conntrack_irc.h
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#ifndef _IP_CONNTRACK_RTSP_H
#define _IP_CONNTRACK_RTSP_H
//#define IP_NF_RTSP_DEBUG 1
#define IP_NF_RTSP_VERSION "0.6.21"
#ifdef _KERNEL_
/* port block types */
typedef enum {
pb_single, /* client_port=x */
pb_range, /* client_port=x-y */
pb_discon /* client_port=x/y (rtspbis) */
} portblock_t;
/* We record seq number and length of rtsp headers here, all in host order. */
/*
* This structure is per expected connection. It is a member of struct
* ip_conntrack_expect. The TCP SEQ for the conntrack expect is stored
* there and we are expected to only store the length of the data which
* needs replaced. If a packet contains multiple RTSP messages, we create
* one expected connection per message.
*
* We use these variables to mark the entire header block. This may seem
* like overkill, but the nature of RTSP requires it. A header may appear
* multiple times in a message. We must treat two Transport headers the
* same as one Transport header with two entries.
*/
struct ip_ct_rtsp_expect
{
u_int32_t len; /* length of header block */
portblock_t pbtype; /* Type of port block that was requested */
u_int16_t loport; /* Port that was requested, low or first */
u_int16_t hiport; /* Port that was requested, high or second */
#if 0
uint method; /* RTSP method */
uint cseq; /* CSeq from request */
#endif
};
extern unsigned int (ip_nat_rtsp_hook)(struct sk_buff *pskb,
enum ip_conntrack_info ctinfo,
unsigned int matchoff, unsigned int matchlen,
struct ip_ct_rtsp_expect *expinfo,
struct ip_conntrack_expect *exp);
#define RTSP_PORT 554
#endif /* _KERNEL_ */
#endif /* _IP_CONNTRACK_RTSP_H */
diff -Naur linux-2.6.19.2/net/ipv4/netfilter/ip_conntrack_rtsp.c linux-2.6.19.2-rtsp/net/ipv4/netfilter/ip_conntrack_rtsp.c
--- linux-2.6.19.2/net/ipv4/netfilter/ip_conntrack_rtsp.c 1970-01-01 01:00:00.000000000 0100
linux-2.6.19.2-rtsp/net/ipv4/netfilter/ip_conntrack_rtsp.c 2007-01-27 18:22:32.000000000 0100
@@ -0,0 1,537 @@
/*
* RTSP extension for IP connection tracking
* (C) 2003 by Tom Marshall <tmarshall@real.com>
* based on ip_conntrack_irc.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Module load syntax:
* insmod ip_conntrack_rtsp.o ports=port1,port2,...port<MAX_PORTS>
* max_outstanding=n setup_timeout=secs
*
* If no ports are specified, the default will be port 554.
*
* With max_outstanding you can define the maximum number of not yet
* answered SETUP requests per RTSP session (default 8).
* With setup_timeout you can specify how long the system waits for
* an expected data channel (default 300 seconds).
*
* 2005-02-13: Harald Welte <laforge@netfilter.org>
* - port to 2.6
* - update to recent post-2.6.11 api changes
*/
/* #include <linux/config.h>
*/
#include <linux/module.h>
#include <linux/netfilter.h>
#include <linux/ip.h>
#include <linux/inet.h>
#include <net/checksum.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/netfilter_ipv4/ip_conntrack_rtsp.h>
#include <linux/ctype.h>
#define NF_NEED_STRNCASECMP
#define NF_NEED_STRTOU16
#define NF_NEED_STRTOU32
#define NF_NEED_NEXTLINE
#include <linux/netfilter_helpers.h>
#define NF_NEED_MIME_NEXTLINE
#include <linux/netfilter_mime.h>
#define MAX_SIMUL_SETUP 8 /* XXX: use max_outstanding */
#define IP_NF_RTSP_DEBUG
#define INFOP(fmt, args...) printk(KERN_INFO "%s: %s: " fmt, _FILE_, _FUNCTION_ , ## args)
#ifdef IP_NF_RTSP_DEBUG
#define DEBUGP(fmt, args...) printk(KERN_DEBUG "%s: %s: " fmt, _FILE_, _FUNCTION_ , ## args)
#else
#define DEBUGP(fmt, args...)
#endif
#define MAX_PORTS 8
static int ports[MAX_PORTS];
static int num_ports = 0;
static int max_outstanding = 8;
static unsigned int setup_timeout = 300;
MODULE_AUTHOR("Tom Marshall <tmarshall@real.com>");
MODULE_DESCRIPTION("RTSP connection tracking module");
MODULE_LICENSE("GPL");
module_param_array(ports, int, &num_ports, 0400);
MODULE_PARM_DESC(ports, "port numbers of RTSP servers");
module_param(max_outstanding, int, 0400);
MODULE_PARM_DESC(max_outstanding, "max number of outstanding SETUP requests per RTSP session");
module_param(setup_timeout, int, 0400);
MODULE_PARM_DESC(setup_timeout, "timeout on for unestablished data channels");
static char *rtsp_buffer;
static DEFINE_SPINLOCK(rtsp_buffer_lock);
unsigned int (ip_nat_rtsp_hook)(struct sk_buff *pskb,
enum ip_conntrack_info ctinfo,
unsigned int matchoff, unsigned int matchlen,struct ip_ct_rtsp_expect* prtspexp,
struct ip_conntrack_expect *exp);
EXPORT_SYMBOL_GPL(ip_nat_rtsp_hook);
/*
* Max mappings we will allow for one RTSP connection (for RTP, the number
* of allocated ports is twice this value). Note that SMIL burns a lot of
* ports so keep this reasonably high. If this is too low, you will see a
* lot of "no free client map entries" messages.
*/
#define MAX_PORT_MAPS 16
/*** default port list was here in the masq code: 554, 3030, 4040 ***/
#define SKIP_WSPACE(ptr,len,off) while(off < len && isspace(*(ptr off))) { off ; }
/*
* Parse an RTSP packet.
*
* Returns zero if parsing failed.
*
* Parameters:
* IN ptcp tcp data pointer
* IN tcplen tcp data len
* IN/OUT ptcpoff points to current tcp offset
* OUT phdrsoff set to offset of rtsp headers
* OUT phdrslen set to length of rtsp headers
* OUT pcseqoff set to offset of CSeq header
* OUT pcseqlen set to length of CSeq header
*/
static int
rtsp_parse_message(char* ptcp, uint tcplen, uint* ptcpoff,
uint* phdrsoff, uint* phdrslen,
uint* pcseqoff, uint* pcseqlen,
uint* transoff, uint* translen)
{
uint entitylen = 0;
uint lineoff;
uint linelen;
if (!nf_nextline(ptcp, tcplen, ptcpoff, &lineoff, &linelen))
return 0;
phdrsoff = ptcpoff;
while (nf_mime_nextline(ptcp, tcplen, ptcpoff, &lineoff, &linelen)) {
if (linelen == 0) {
if (entitylen > 0)
ptcpoff = min(entitylen, tcplen - ptcpoff);
break;
}
if (lineoff linelen > tcplen) {
INFOP("!! overrun !!\n");
break;
}
if (nf_strncasecmp(ptcp lineoff, "CSeq:", 5) == 0) {
*pcseqoff = lineoff;
*pcseqlen = linelen;
}
if (nf_strncasecmp(ptcp lineoff, "Transport:", 10) == 0) {
*transoff = lineoff;
*translen = linelen;
}
if (nf_strncasecmp(ptcp lineoff, "Content-Length:", 15) == 0) {
uint off = lineoff 15;
SKIP_WSPACE(ptcp lineoff, linelen, off);
nf_strtou32(ptcp off, &entitylen);
}
}
phdrslen = (ptcpoff) - (*phdrsoff);
return 1;
}
/*
* Find lo/hi client ports (if any) in transport header
* In:
* ptcp, tcplen = packet
* tranoff, tranlen = buffer to search
*
* Out:
* pport_lo, pport_hi = lo/hi ports (host endian)
*
* Returns nonzero if any client ports found
*
* Note: it is valid (and expected) for the client to request multiple
* transports, so we need to parse the entire line.
*/
static int
rtsp_parse_transport(char* ptran, uint tranlen,
struct ip_ct_rtsp_expect* prtspexp)
{
int rc = 0;
uint off = 0;
if (tranlen < 10 || !iseol(ptran[tranlen-1]) ||
nf_strncasecmp(ptran, "Transport:", 10) != 0) {
INFOP("sanity check failed\n");
return 0;
}
DEBUGP("tran='%.*s'\n", (int)tranlen, ptran);
off = 10;
SKIP_WSPACE(ptran, tranlen, off);
/* Transport: tran;field;field=val,tran;field;field=val,... */
while (off < tranlen) {
const char* pparamend;
uint nextparamoff;
pparamend = memchr(ptran off, ',', tranlen-off);
pparamend = (pparamend == NULL) ? ptran tranlen : pparamend 1;
nextparamoff = pparamend-ptran;
while (off < nextparamoff) {
const char* pfieldend;
uint nextfieldoff;
pfieldend = memchr(ptran off, ';', nextparamoff-off);
nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran 1;
if (strncmp(ptran off, "client_port=", 12) == 0) {
u_int16_t port;
uint numlen;
off = 12;
numlen = nf_strtou16(ptran off, &port);
off = numlen;
if (prtspexp->loport != 0 && prtspexp->loport != port)
DEBUGP("multiple ports found, port %hu ignored\n", port);
else {
DEBUGP("lo port found : %hu\n", port);
prtspexp->loport = prtspexp->hiport = port;
if (ptran[off] == '-') {
off ;
numlen = nf_strtou16(ptran off, &port);
off = numlen;
prtspexp->pbtype = pb_range;
prtspexp->hiport = port;
// If we have a range, assume rtp:
// loport must be even, hiport must be loport 1
if ((prtspexp->loport & 0x0001) != 0 ||
prtspexp->hiport != prtspexp->loport 1) {
DEBUGP("incorrect range: %hu-%hu, correcting\n",
prtspexp->loport, prtspexp->hiport);
prtspexp->loport &= 0xfffe;
prtspexp->hiport = prtspexp->loport 1;
}
} else if (ptran[off] == '/') {
off ;
numlen = nf_strtou16(ptran off, &port);
off = numlen;
prtspexp->pbtype = pb_discon;
prtspexp->hiport = port;
}
rc = 1;
}
}
/*
* Note we don't look for the destination parameter here.
* If we are using NAT, the NAT module will handle it. If not,
* and the client is sending packets elsewhere, the expectation
* will quietly time out.
*/
off = nextfieldoff;
}
off = nextparamoff;
}
return rc;
}
void expected(struct ip_conntrack* ct, struct ip_conntrack_expect *exp)
{
struct ip_nat_multi_range_compat mr;
u_int32_t newdstip, newsrcip, newip;
struct ip_conntrack *master = master_ct(ct);
newdstip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
newsrcip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.ip;
//FIXME (how to port that ?)
//code from 2.4 : newip = (HOOK2MANIP(hooknum) == IP_NAT_MANIP_SRC) ? newsrcip : newdstip;
newip = newdstip;
DEBUGP("newsrcip=%u.%u.%u.%u, newdstip=%u.%u.%u.%u, newip=%u.%u.%u.%u\n",
NIPQUAD(newsrcip), NIPQUAD(newdstip), NIPQUAD(newip));
mr.rangesize = 1;
// We don't want to manip the per-protocol, just the IPs.
mr.range[0].flags = IP_NAT_RANGE_MAP_IPS;
mr.range[0].min_ip = mr.range[0].max_ip = newip;
ip_nat_setup_info(ct, &mr.range[0], NF_IP_PRE_ROUTING);
}
/*** conntrack functions ***/
/* outbound packet: client->server */
static inline int
help_out(struct sk_buff *pskb, unsigned char rb_ptr, unsigned int datalen,
struct ip_conntrack* ct, enum ip_conntrack_info ctinfo)
{
struct ip_ct_rtsp_expect expinfo;
int dir = CTINFO2DIR(ctinfo); /* = IP_CT_DIR_ORIGINAL */
//struct tcphdr* tcph = (void*)iph iph->ihl * 4;
//uint tcplen = pktlen - iph->ihl * 4;
char* pdata = rb_ptr;
//uint datalen = tcplen - tcph->doff * 4;
uint dataoff = 0;
int ret = NF_ACCEPT;
struct ip_conntrack_expect *exp;
memset(&expinfo, 0, sizeof(expinfo));
while (dataoff < datalen) {
uint cmdoff = dataoff;
uint hdrsoff = 0;
uint hdrslen = 0;
uint cseqoff = 0;
uint cseqlen = 0;
uint transoff = 0;
uint translen = 0;
uint off;
if (!rtsp_parse_message(pdata, datalen, &dataoff,
&hdrsoff, &hdrslen,
&cseqoff, &cseqlen,
&transoff, &translen))
break; /* not a valid message */
if (strncmp(pdata cmdoff, "SETUP ", 6) != 0)
continue; /* not a SETUP message */
DEBUGP("found a setup message\n");
off = 0;
if(translen) {
rtsp_parse_transport(pdata transoff, translen, &expinfo);
}
if (expinfo.loport == 0) {
DEBUGP("no udp transports found\n");
continue; /* no udp transports found */
}
DEBUGP("udp transport found, ports=(%d,%hu,%hu)\n",
(int)expinfo.pbtype, expinfo.loport, expinfo.hiport);
exp = ip_conntrack_expect_alloc(ct);
if (!exp) {
ret = NF_DROP;
goto out;
}
exp->master = ct;
exp->expectfn = expected;
exp->flags = 0;
exp->tuple = ((struct ip_conntrack_tuple)
{
{ ct->tuplehash[!dir].tuple.src.ip,
{ 0 }
},
{
ct->tuplehash[!dir].tuple.dst.ip,
{ .udp = { htons(expinfo.loport) } },
IPPROTO_UDP
}
});
exp->mask = ((struct ip_conntrack_tuple)
{
{ 0,
{ 0 }
},
{
0xFFFFFFFF,
{ .udp = { 0xFFFF } }, 0xFF
}
});
if (expinfo.pbtype == pb_range) {
DEBUGP("Changing expectation mask to handle multiple ports\n");
exp->mask.dst.u.udp.port = 0xfffe;
}
DEBUGP("expect_related %u.%u.%u.%u:%u-%u.%u.%u.%u:%u\n",
NIPQUAD(exp->tuple.src.ip),
ntohs(exp->tuple.src.u.udp.port),
NIPQUAD(exp->tuple.dst.ip),
ntohs(exp->tuple.dst.u.udp.port));
if (ip_nat_rtsp_hook)
/* pass the request off to the nat helper */
ret = ip_nat_rtsp_hook(pskb, ctinfo, hdrsoff, hdrslen, &expinfo, exp);
else if (ip_conntrack_expect_related(exp) != 0) {
INFOP("ip_conntrack_expect_related failed\n");
ret = NF_DROP;
}
ip_conntrack_expect_put(exp);
goto out;
}
out:
return ret;
}
/* inbound packet: server->client */
static inline int
help_in(struct sk_buff **pskb, size_t pktlen,
struct ip_conntrack* ct, enum ip_conntrack_info ctinfo)
{
return NF_ACCEPT;
}
static int help(struct sk_buff *pskb, struct ip_conntrack ct, enum
ip_conntrack_info ctinfo)
{
struct tcphdr _tcph, *th;
unsigned int dataoff, datalen;
char *rb_ptr;
int ret = NF_DROP;
/* Until there's been traffic both ways, don't look in packets. */
if (ctinfo != IP_CT_ESTABLISHED &&
ctinfo != IP_CT_ESTABLISHED IP_CT_IS_REPLY) {
DEBUGP("conntrackinfo = %u\n", ctinfo);
return NF_ACCEPT;
}
/* Not whole TCP header? */
th = skb_header_pointer(pskb, (pskb)->nh.iph->ihl*4,
sizeof(_tcph), &_tcph);
if (!th)
return NF_ACCEPT;
/* No data ? */
dataoff = (pskb)->nh.iph->ihl4 th->doff*4;
datalen = (*pskb)->len - dataoff;
if (dataoff >= (*pskb)->len)
return NF_ACCEPT;
spin_lock_bh(&rtsp_buffer_lock);
rb_ptr = skb_header_pointer(*pskb, dataoff,
(*pskb)->len - dataoff, rtsp_buffer);
BUG_ON(rb_ptr == NULL);
#if 0
/* Checksum invalid? Ignore. */
/* FIXME: Source route IP option packets --RR */
if (tcp_v4_check(tcph, tcplen, iph->saddr, iph->daddr,
csum_partial((char*)tcph, tcplen, 0)))
{
DEBUGP("bad csum: %p %u %u.%u.%u.%u %u.%u.%u.%u\n",
tcph, tcplen, NIPQUAD(iph->saddr), NIPQUAD(iph->daddr));
return NF_ACCEPT;
}
#endif
switch (CTINFO2DIR(ctinfo)) {
case IP_CT_DIR_ORIGINAL:
ret = help_out(pskb, rb_ptr, datalen, ct, ctinfo);
break;
case IP_CT_DIR_REPLY:
DEBUGP("IP_CT_DIR_REPLY\n");
/* inbound packet: server->client */
ret = NF_ACCEPT;
break;
}
spin_unlock_bh(&rtsp_buffer_lock);
return ret;
}
static struct ip_conntrack_helper rtsp_helpers[MAX_PORTS];
static char rtsp_names[MAX_PORTS][10];
/* This function is intentionally NOT defined as __exit */
static void
fini(void)
{
int i;
for (i = 0; i < num_ports; i ) {
DEBUGP("unregistering port %d\n", ports[i]);
ip_conntrack_helper_unregister(&rtsp_helpers[i]);
}
kfree(rtsp_buffer);
}
static int __init
init(void)
{
int i, ret;
struct ip_conntrack_helper *hlpr;
char *tmpname;
printk("ip_conntrack_rtsp v" IP_NF_RTSP_VERSION " loading\n");
if (max_outstanding < 1) {
printk("ip_conntrack_rtsp: max_outstanding must be a positive integer\n");
return -EBUSY;
}
if (setup_timeout < 0) {
printk("ip_conntrack_rtsp: setup_timeout must be a positive integer\n");
return -EBUSY;
}
rtsp_buffer = kmalloc(65536, GFP_KERNEL);
if (!rtsp_buffer)
return -ENOMEM;
/* If no port given, default to standard rtsp port */
if (ports[0] == 0) {
ports[0] = RTSP_PORT;
}
for (i = 0; (i < MAX_PORTS) && ports[i]; i ) {
hlpr = &rtsp_helpers[i];
memset(hlpr, 0, sizeof(struct ip_conntrack_helper));
hlpr->tuple.src.u.tcp.port = htons(ports[i]);
hlpr->tuple.dst.protonum = IPPROTO_TCP;
hlpr->mask.src.u.tcp.port = 0xFFFF;
hlpr->mask.dst.protonum = 0xFF;
hlpr->max_expected = max_outstanding;
hlpr->timeout = setup_timeout;
hlpr->me = THIS_MODULE;
hlpr->help = help;
tmpname = &rtsp_names[i][0];
if (ports[i] == RTSP_PORT) {
sprintf(tmpname, "rtsp");
} else {
sprintf(tmpname, "rtsp-%d", i);
}
hlpr->name = tmpname;
DEBUGP("port #%d: %d\n", i, ports[i]);
ret = ip_conntrack_helper_register(hlpr);
if (ret) {
printk("ip_conntrack_rtsp: ERROR registering port %d\n", ports[i]);
fini();
return -EBUSY;
}
num_ports ;
}
return 0;
}
module_init(init);
module_exit(fini);
diff -Naur linux-2.6.19.2/net/ipv4/netfilter/ip_nat_rtsp.c linux-2.6.19.2-rtsp/net/ipv4/netfilter/ip_nat_rtsp.c
--- linux-2.6.19.2/net/ipv4/netfilter/ip_nat_rtsp.c 1970-01-01 01:00:00.000000000 0100
linux-2.6.19.2-rtsp/net/ipv4/netfilter/ip_nat_rtsp.c 2007-01-27 18:18:35.000000000 0100
@@ -0,0 1,475 @@
/*
* RTSP extension for TCP NAT alteration
* (C) 2003 by Tom Marshall <tmarshall@real.com>
* based on ip_nat_irc.c
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Module load syntax:
* insmod ip_nat_rtsp.o ports=port1,port2,...port<MAX_PORTS>
* stunaddr=<address>
* destaction=[auto|strip|none]
*
* If no ports are specified, the default will be port 554 only.
*
* stunaddr specifies the address used to detect that a client is using STUN.
* If this address is seen in the destination parameter, it is assumed that
* the client has already punched a UDP hole in the firewall, so we don't
* mangle the client_port. If none is specified, it is autodetected. It
* only needs to be set if you have multiple levels of NAT. It should be
* set to the external address that the STUN clients detect. Note that in
* this case, it will not be possible for clients to use UDP with servers
* between the NATs.
*
* If no destaction is specified, auto is used.
* destaction=auto: strip destination parameter if it is not stunaddr.
* destaction=strip: always strip destination parameter (not recommended).
* destaction=none: do not touch destination parameter (not recommended).
*/
#include <linux/module.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/kernel.h>
#include <net/tcp.h>
#include <linux/netfilter_ipv4/ip_nat.h>
#include <linux/netfilter_ipv4/ip_nat_helper.h>
#include <linux/netfilter_ipv4/ip_nat_rule.h>
#include <linux/netfilter_ipv4/ip_conntrack_rtsp.h>
#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
#include <linux/inet.h>
#include <linux/ctype.h>
#define NF_NEED_STRNCASECMP
#define NF_NEED_STRTOU16
#include <linux/netfilter_helpers.h>
#define NF_NEED_MIME_NEXTLINE
#include <linux/netfilter_mime.h>
#define INFOP(fmt, args...) printk(KERN_INFO "%s: %s: " fmt, _FILE_, _FUNCTION_ , ## args)
#define IP_NF_RTSP_DEBUG
#ifdef IP_NF_RTSP_DEBUG
#define DEBUGP(fmt, args...) printk(KERN_DEBUG "%s: %s: " fmt, _FILE_, _FUNCTION_ , ## args)
#else
#define DEBUGP(fmt, args...)
#endif
#define MAX_PORTS 8
#define DSTACT_AUTO 0
#define DSTACT_STRIP 1
#define DSTACT_NONE 2
static char* stunaddr = NULL;
static char* destaction = NULL;
static u_int32_t extip = 0;
static int dstact = 0;
MODULE_AUTHOR("Tom Marshall <tmarshall@real.com>");
MODULE_DESCRIPTION("RTSP network address translation module");
MODULE_LICENSE("GPL");
module_param(stunaddr, charp, 0644);
MODULE_PARM_DESC(stunaddr, "Address for detecting STUN");
module_param(destaction, charp, 0644);
MODULE_PARM_DESC(destaction, "Action for destination parameter (auto/strip/none)");
#define SKIP_WSPACE(ptr,len,off) while(off < len && isspace(*(ptr off))) { off ; }
/*** helper functions ***/
static void
get_skb_tcpdata(struct sk_buff* skb, char** pptcpdata, uint* ptcpdatalen)
{
struct iphdr* iph = (struct iphdr*)skb->nh.iph;
struct tcphdr* tcph = (struct tcphdr*)((char*)iph iph->ihl*4);
pptcpdata = (char)tcph tcph->doff*4;
ptcpdatalen = ((char)skb->h.raw skb->len) - *pptcpdata;
}
/*** nat functions ***/
/*
* Mangle the "Transport:" header:
* - Replace all occurences of "client_port=<spec>"
* - Handle destination parameter
*
* In:
* ct, ctinfo = conntrack context
* pskb = packet
* tranoff = Transport header offset from TCP data
* tranlen = Transport header length (incl. CRLF)
* rport_lo = replacement low port (host endian)
* rport_hi = replacement high port (host endian)
*
* Returns packet size difference.
*
* Assumes that a complete transport header is present, ending with CR or LF
*/
static int
rtsp_mangle_tran(enum ip_conntrack_info ctinfo,
struct ip_conntrack_expect* exp,
struct ip_ct_rtsp_expect* prtspexp,
struct sk_buff** pskb, uint tranoff, uint tranlen)
{
char* ptcp;
uint tcplen;
char* ptran;
char rbuf1[16]; /* Replacement buffer (one port) */
uint rbuf1len; /* Replacement len (one port) */
char rbufa[16]; /* Replacement buffer (all ports) */
uint rbufalen; /* Replacement len (all ports) */
u_int32_t newip;
u_int16_t loport, hiport;
uint off = 0;
uint diff; /* Number of bytes we removed */
struct ip_conntrack *ct = exp->master;
struct ip_conntrack_tuple t;
char szextaddr[15 1];
uint extaddrlen;
int is_stun;
get_skb_tcpdata(*pskb, &ptcp, &tcplen);
ptran = ptcp tranoff;
if (tranoff tranlen > tcplen || tcplen-tranoff < tranlen ||
tranlen < 10 || !iseol(ptran[tranlen-1]) ||
nf_strncasecmp(ptran, "Transport:", 10) != 0)
{
INFOP("sanity check failed\n");
return 0;
}
off = 10;
SKIP_WSPACE(ptcp tranoff, tranlen, off);
newip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip;
t = exp->tuple;
t.dst.ip = newip;
extaddrlen = extip ? sprintf(szextaddr, "%u.%u.%u.%u", NIPQUAD(extip))
: sprintf(szextaddr, "%u.%u.%u.%u", NIPQUAD(newip));
DEBUGP("stunaddr=%s (%s)\n", szextaddr, (extip?"forced":"auto"));
rbuf1len = rbufalen = 0;
switch (prtspexp->pbtype)
{
case pb_single:
for (loport = prtspexp->loport; loport != 0; loport ) /* XXX: improper wrap? */
{
t.dst.u.udp.port = htons(loport);
if (ip_conntrack_expect_related(exp) == 0)
{
DEBUGP("using port %hu\n", loport);
break;
}
}
if (loport != 0)
{
rbuf1len = sprintf(rbuf1, "%hu", loport);
rbufalen = sprintf(rbufa, "%hu", loport);
}
break;
case pb_range:
for (loport = prtspexp->loport; loport != 0; loport = 2) /* XXX: improper wrap? */
{
t.dst.u.udp.port = htons(loport);
if (ip_conntrack_expect_related(exp) == 0)
{
hiport = loport ~exp->mask.dst.u.udp.port;
DEBUGP("using ports %hu-%hu\n", loport, hiport);
break;
}
}
if (loport != 0)
{
rbuf1len = sprintf(rbuf1, "%hu", loport);
rbufalen = sprintf(rbufa, "%hu-%hu", loport, loport 1);
}
break;
case pb_discon:
for (loport = prtspexp->loport; loport != 0; loport ) /* XXX: improper wrap? */
{
t.dst.u.udp.port = htons(loport);
if (ip_conntrack_expect_related(exp) == 0)
{
DEBUGP("using port %hu (1 of 2)\n", loport);
break;
}
}
for (hiport = prtspexp->hiport; hiport != 0; hiport ) /* XXX: improper wrap? */
{
t.dst.u.udp.port = htons(hiport);
if (ip_conntrack_expect_related(exp) == 0)
{
DEBUGP("using port %hu (2 of 2)\n", hiport);
break;
}
}
if (loport != 0 && hiport != 0)
{
rbuf1len = sprintf(rbuf1, "%hu", loport);
if (hiport == loport 1)
{
rbufalen = sprintf(rbufa, "%hu-%hu", loport, hiport);
}
else
{
rbufalen = sprintf(rbufa, "%hu/%hu", loport, hiport);
}
}
break;
}
if (rbuf1len == 0)
{
return 0; /* cannot get replacement port(s) */
}
/* Transport: tran;field;field=val,tran;field;field=val,... */
while (off < tranlen)
{
uint saveoff;
const char* pparamend;
uint nextparamoff;
pparamend = memchr(ptran off, ',', tranlen-off);
pparamend = (pparamend == NULL) ? ptran tranlen : pparamend 1;
nextparamoff = pparamend-ptcp;
/*
* We pass over each param twice. On the first pass, we look for a
* destination= field. It is handled by the security policy. If it
* is present, allowed, and equal to our external address, we assume
* that STUN is being used and we leave the client_port= field alone.
*/
is_stun = 0;
saveoff = off;
while (off < nextparamoff)
{
const char* pfieldend;
uint nextfieldoff;
pfieldend = memchr(ptran off, ';', nextparamoff-off);
nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran 1;
if (dstact != DSTACT_NONE && strncmp(ptran off, "destination=", 12) == 0)
{
if (strncmp(ptran off 12, szextaddr, extaddrlen) == 0)
{
is_stun = 1;
}
if (dstact == DSTACT_STRIP || (dstact == DSTACT_AUTO && !is_stun))
{
diff = nextfieldoff-off;
if (!ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
off, diff, NULL, 0))
{
/* mangle failed, all we can do is bail */
ip_conntrack_unexpect_related(exp);
return 0;
}
get_skb_tcpdata(*pskb, &ptcp, &tcplen);
ptran = ptcp tranoff;
tranlen -= diff;
nextparamoff -= diff;
nextfieldoff -= diff;
}
}
off = nextfieldoff;
}
if (is_stun)
{
continue;
}
off = saveoff;
while (off < nextparamoff)
{
const char* pfieldend;
uint nextfieldoff;
pfieldend = memchr(ptran off, ';', nextparamoff-off);
nextfieldoff = (pfieldend == NULL) ? nextparamoff : pfieldend-ptran 1;
if (strncmp(ptran off, "client_port=", 12) == 0)
{
u_int16_t port;
uint numlen;
uint origoff;
uint origlen;
char* rbuf = rbuf1;
uint rbuflen = rbuf1len;
off = 12;
origoff = (ptran-ptcp) off;
origlen = 0;
numlen = nf_strtou16(ptran off, &port);
off = numlen;
origlen = numlen;
if (port != prtspexp->loport)
{
DEBUGP("multiple ports found, port %hu ignored\n", port);
}
else
{
if (ptran[off] == '-' || ptran[off] == '/')
{
off ;
origlen ;
numlen = nf_strtou16(ptran off, &port);
off = numlen;
origlen = numlen;
rbuf = rbufa;
rbuflen = rbufalen;
}
/*
* note we cannot just memcpy() if the sizes are the same.
* the mangle function does skb resizing, checks for a
* cloned skb, and updates the checksums.
*
* parameter 4 below is offset from start of tcp data.
*/
diff = origlen-rbuflen;
if (!ip_nat_mangle_tcp_packet(pskb, ct, ctinfo,
origoff, origlen, rbuf, rbuflen))
{
/* mangle failed, all we can do is bail */
ip_conntrack_unexpect_related(exp);
return 0;
}
get_skb_tcpdata(*pskb, &ptcp, &tcplen);
ptran = ptcp tranoff;
tranlen -= diff;
nextparamoff -= diff;
nextfieldoff -= diff;
}
}
off = nextfieldoff;
}
off = nextparamoff;
}
return 1;
}
static uint
help_out(struct sk_buff **pskb, enum ip_conntrack_info ctinfo,
unsigned int matchoff, unsigned int matchlen,struct ip_ct_rtsp_expect* prtspexp,
struct ip_conntrack_expect* exp)
{
char* ptcp;
uint tcplen;
uint hdrsoff;
uint hdrslen;
uint lineoff;
uint linelen;
uint off;
struct iphdr* iph = (struct iphdr*)(*pskb)->nh.iph;
struct tcphdr* tcph = (struct tcphdr*)((void*)iph iph->ihl*4);
get_skb_tcpdata(*pskb, &ptcp, &tcplen);
hdrsoff = matchoff;//exp->seq - ntohl(tcph->seq);
hdrslen = matchlen;
off = hdrsoff;
DEBUGP("NAT rtsp help_out\n");
while (nf_mime_nextline(ptcp, hdrsoff hdrslen, &off, &lineoff, &linelen))
{
if (linelen == 0)
{
break;
}
if (off > hdrsoff hdrslen)
{
INFOP("!! overrun !!");
break;
}
DEBUGP("hdr: len=%u, %.*s", linelen, (int)linelen, ptcp lineoff);
if (nf_strncasecmp(ptcp lineoff, "Transport:", 10) == 0)
{
uint oldtcplen = tcplen;
DEBUGP("hdr: Transport\n");
if (!rtsp_mangle_tran(ctinfo, exp, prtspexp, pskb, lineoff, linelen))
{
DEBUGP("hdr: Transport mangle failed");
break;
}
get_skb_tcpdata(*pskb, &ptcp, &tcplen);
hdrslen -= (oldtcplen-tcplen);
off -= (oldtcplen-tcplen);
lineoff -= (oldtcplen-tcplen);
linelen -= (oldtcplen-tcplen);
DEBUGP("rep: len=%u, %.*s", linelen, (int)linelen, ptcp lineoff);
}
}
return NF_ACCEPT;
}
static unsigned int
help(struct sk_buff **pskb, enum ip_conntrack_info ctinfo,
unsigned int matchoff, unsigned int matchlen,struct ip_ct_rtsp_expect* prtspexp,
struct ip_conntrack_expect* exp)
{
int dir = CTINFO2DIR(ctinfo);
int rc = NF_ACCEPT;
switch (dir)
{
case IP_CT_DIR_ORIGINAL:
rc = help_out(pskb, ctinfo, matchoff, matchlen, prtspexp, exp);
break;
case IP_CT_DIR_REPLY:
DEBUGP("unmangle ! %u\n", ctinfo);
/* XXX: unmangle */
rc = NF_ACCEPT;
break;
}
//UNLOCK_BH(&ip_rtsp_lock);
return rc;
}
static void __exit fini(void)
{
ip_nat_rtsp_hook = NULL;
synchronize_net();
}
static int __init init(void)
{
printk("ip_nat_rtsp v" IP_NF_RTSP_VERSION " loading\n");
BUG_ON(ip_nat_rtsp_hook);
ip_nat_rtsp_hook = help;
if (stunaddr != NULL)
extip = in_aton(stunaddr);
if (destaction != NULL) {
if (strcmp(destaction, "auto") == 0)
dstact = DSTACT_AUTO;
if (strcmp(destaction, "strip") == 0)
dstact = DSTACT_STRIP;
if (strcmp(destaction, "none") == 0)
dstact = DSTACT_NONE;
}
return 0;
}
module_init(init);
module_exit(fini);
diff -Naur linux-2.6.19.2/net/ipv4/netfilter/Kconfig linux-2.6.19.2-rtsp/net/ipv4/netfilter/Kconfig
--- linux-2.6.19.2/net/ipv4/netfilter/Kconfig 2007-01-10 20:10:37.000000000 0100
linux-2.6.19.2-rtsp/net/ipv4/netfilter/Kconfig 2007-09-05 20:44:49.000000000 0200
@@ -623,5 623,21 @@
Allows altering the ARP packet payload: source and destination
hardware and network addresses.
config IP_NF_NAT_RTSP
tristate
depends on IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
default IP_NF_NAT if IP_NF_RTSP=y
default m if IP_NF_RTSP=m
config IP_NF_RTSP
tristate ' RTSP protocol support'
depends on IP_NF_CONNTRACK
help
Support the RTSP protocol. This allows UDP transports to be setup
properly, including RTP and RDT.
If you want to compile it as a module, say 'M' here and read
Documentation/modules.txt. If unsure, say 'Y'.
endmenu
diff -Naur linux-2.6.19.2/net/ipv4/netfilter/Makefile linux-2.6.19.2-rtsp/net/ipv4/netfilter/Makefile
--- linux-2.6.19.2/net/ipv4/netfilter/Makefile 2007-01-10 20:10:37.000000000 0100
linux-2.6.19.2-rtsp/net/ipv4/netfilter/Makefile 2007-09-05 20:44:48.000000000 0200
@@ -26,6 26,11 @@
# connection tracking helpers
obj-$(CONFIG_IP_NF_H323) = ip_conntrack_h323.o
# rtsp protocol support
obj-$(CONFIG_IP_NF_RTSP) = ip_conntrack_rtsp.o
obj-$(CONFIG_IP_NF_NAT_RTSP) = ip_nat_rtsp.o
obj-$(CONFIG_IP_NF_PPTP) = ip_conntrack_pptp.o
obj-$(CONFIG_IP_NF_AMANDA) = ip_conntrack_amanda.o
obj-$(CONFIG_IP_NF_TFTP) = ip_conntrack_tftp.o