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openwrt/package/network/utils/xtables-addons/patches-1.x/100-add-rtsp-conntrack.patch
Jo-Philipp Wich 3b798d819d xtables-addons: move to package/, add myself as maintainer 
SVN-Revision: 35193
2013-01-17 12:29:26 +00:00

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--- /dev/null
+++ b/extensions/rtsp/Kbuild
@@ -0,0 +1,4 @@
+# -*- Makefile -*-
+
+obj-m += nf_nat_rtsp.o
+obj-m += nf_conntrack_rtsp.o
--- /dev/null
+++ b/extensions/rtsp/netfilter_helpers.h
@@ -0,0 +1,133 @@
+/*
+ * Helpers for netfiler modules. This file provides implementations for basic
+ * functions such as strncasecmp(), etc.
+ *
+ * gcc will warn for defined but unused functions, so we only include the
+ * functions requested. The following macros are used:
+ * NF_NEED_STRNCASECMP nf_strncasecmp()
+ * NF_NEED_STRTOU16 nf_strtou16()
+ * NF_NEED_STRTOU32 nf_strtou32()
+ */
+#ifndef _NETFILTER_HELPERS_H
+#define _NETFILTER_HELPERS_H
+
+/* Only include these functions for kernel code. */
+#ifdef __KERNEL__
+
+#include <linux/ctype.h>
+#define iseol(c) ( (c) == '\r' || (c) == '\n' )
+
+/*
+ * The standard strncasecmp()
+ */
+#ifdef NF_NEED_STRNCASECMP
+static int
+nf_strncasecmp(const char* s1, const char* s2, u_int32_t len)
+{
+ if (s1 == NULL || s2 == NULL)
+ {
+ if (s1 == NULL && s2 == NULL)
+ {
+ return 0;
+ }
+ return (s1 == NULL) ? -1 : 1;
+ }
+ while (len > 0 && tolower(*s1) == tolower(*s2))
+ {
+ len--;
+ s1++;
+ s2++;
+ }
+ return ( (len == 0) ? 0 : (tolower(*s1) - tolower(*s2)) );
+}
+#endif /* NF_NEED_STRNCASECMP */
+
+/*
+ * Parse a string containing a 16-bit unsigned integer.
+ * Returns the number of chars used, or zero if no number is found.
+ */
+#ifdef NF_NEED_STRTOU16
+static int
+nf_strtou16(const char* pbuf, u_int16_t* pval)
+{
+ int n = 0;
+
+ *pval = 0;
+ while (isdigit(pbuf[n]))
+ {
+ *pval = (*pval * 10) + (pbuf[n] - '0');
+ n++;
+ }
+
+ return n;
+}
+#endif /* NF_NEED_STRTOU16 */
+
+/*
+ * Parse a string containing a 32-bit unsigned integer.
+ * Returns the number of chars used, or zero if no number is found.
+ */
+#ifdef NF_NEED_STRTOU32
+static int
+nf_strtou32(const char* pbuf, u_int32_t* pval)
+{
+ int n = 0;
+
+ *pval = 0;
+ while (pbuf[n] >= '0' && pbuf[n] <= '9')
+ {
+ *pval = (*pval * 10) + (pbuf[n] - '0');
+ n++;
+ }
+
+ return n;
+}
+#endif /* NF_NEED_STRTOU32 */
+
+/*
+ * Given a buffer and length, advance to the next line and mark the current
+ * line.
+ */
+#ifdef NF_NEED_NEXTLINE
+static int
+nf_nextline(char* p, uint len, uint* poff, uint* plineoff, uint* plinelen)
+{
+ uint off = *poff;
+ uint physlen = 0;
+
+ if (off >= len)
+ {
+ return 0;
+ }
+
+ while (p[off] != '\n')
+ {
+ if (len-off <= 1)
+ {
+ return 0;
+ }
+
+ physlen++;
+ off++;
+ }
+
+ /* if we saw a crlf, physlen needs adjusted */
+ if (physlen > 0 && p[off] == '\n' && p[off-1] == '\r')
+ {
+ physlen--;
+ }
+
+ /* advance past the newline */
+ off++;
+
+ *plineoff = *poff;
+ *plinelen = physlen;
+ *poff = off;
+
+ return 1;
+}
+#endif /* NF_NEED_NEXTLINE */
+
+#endif /* __KERNEL__ */
+
+#endif /* _NETFILTER_HELPERS_H */
--- /dev/null
+++ b/extensions/rtsp/netfilter_mime.h
@@ -0,0 +1,89 @@
+/*
+ * MIME functions for netfilter modules. This file provides implementations
+ * for basic MIME parsing. MIME headers are used in many protocols, such as
+ * HTTP, RTSP, SIP, etc.
+ *
+ * gcc will warn for defined but unused functions, so we only include the
+ * functions requested. The following macros are used:
+ * NF_NEED_MIME_NEXTLINE nf_mime_nextline()
+ */
+#ifndef _NETFILTER_MIME_H
+#define _NETFILTER_MIME_H
+
+/* Only include these functions for kernel code. */
+#ifdef __KERNEL__
+
+#include <linux/ctype.h>
+
+/*
+ * Given a buffer and length, advance to the next line and mark the current
+ * line. If the current line is empty, *plinelen will be set to zero. If
+ * not, it will be set to the actual line length (including CRLF).
+ *
+ * 'line' in this context means logical line (includes LWS continuations).
+ * Returns 1 on success, 0 on failure.
+ */
+#ifdef NF_NEED_MIME_NEXTLINE
+static int
+nf_mime_nextline(char* p, uint len, uint* poff, uint* plineoff, uint* plinelen)
+{
+ uint off = *poff;
+ uint physlen = 0;
+ int is_first_line = 1;
+
+ if (off >= len)
+ {
+ return 0;
+ }
+
+ do
+ {
+ while (p[off] != '\n')
+ {
+ if (len-off <= 1)
+ {
+ return 0;
+ }
+
+ physlen++;
+ off++;
+ }
+
+ /* if we saw a crlf, physlen needs adjusted */
+ if (physlen > 0 && p[off] == '\n' && p[off-1] == '\r')
+ {
+ physlen--;
+ }
+
+ /* advance past the newline */
+ off++;
+
+ /* check for an empty line */
+ if (physlen == 0)
+ {
+ break;
+ }
+
+ /* check for colon on the first physical line */
+ if (is_first_line)
+ {
+ is_first_line = 0;
+ if (memchr(p+(*poff), ':', physlen) == NULL)
+ {
+ return 0;
+ }
+ }
+ }
+ while (p[off] == ' ' || p[off] == '\t');
+
+ *plineoff = *poff;
+ *plinelen = (physlen == 0) ? 0 : (off - *poff);
+ *poff = off;
+
+ return 1;
+}
+#endif /* NF_NEED_MIME_NEXTLINE */
+
+#endif /* __KERNEL__ */
+
+#endif /* _NETFILTER_MIME_H */
--- /dev/null
+++ b/extensions/rtsp/nf_conntrack_rtsp.c
@@ -0,0 +1,519 @@
+/*
+ * RTSP extension for IP connection tracking
+ * (C) 2003 by Tom Marshall <tmarshall at 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 nf_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 at netfilter.org>
+ * - port to 2.6
+ * - update to recent post-2.6.11 api changes
+ * 2006-09-14: Steven Van Acker <deepstar at singularity.be>
+ * - removed calls to NAT code from conntrack helper: NAT no longer needed to use rtsp-conntrack
+ * 2007-04-18: Michael Guntsche <mike at it-loops.com>
+ * - Port to new NF API
+ */
+
+#include <linux/module.h>
+#include <linux/netfilter.h>
+#include <linux/ip.h>
+#include <linux/inet.h>
+#include <net/tcp.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include "nf_conntrack_rtsp.h"
+
+#define NF_NEED_STRNCASECMP
+#define NF_NEED_STRTOU16
+#define NF_NEED_STRTOU32
+#define NF_NEED_NEXTLINE
+#include "netfilter_helpers.h"
+#define NF_NEED_MIME_NEXTLINE
+#include "netfilter_mime.h"
+
+#include <linux/ctype.h>
+#define MAX_SIMUL_SETUP 8 /* XXX: use max_outstanding */
+
+#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 at 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);
+
+static struct nf_conntrack_expect_policy rtsp_exp_policy;
+
+unsigned int (*nf_nat_rtsp_hook)(struct sk_buff *skb,
+ enum ip_conntrack_info ctinfo,
+ unsigned int matchoff, unsigned int matchlen,struct ip_ct_rtsp_expect* prtspexp,
+ struct nf_conntrack_expect *exp);
+void (*nf_nat_rtsp_hook_expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
+
+EXPORT_SYMBOL_GPL(nf_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) {
+ pr_info("!! 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) {
+ pr_info("sanity check failed\n");
+ return 0;
+ }
+
+ pr_debug("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)
+ pr_debug("multiple ports found, port %hu ignored\n", port);
+ else {
+ pr_debug("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) {
+ pr_debug("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 nf_conn *ct, struct nf_conntrack_expect *exp)
+{
+ typeof(nf_nat_rtsp_hook_expectfn) nf_nat_rtsp_expectfn;
+ nf_nat_rtsp_expectfn = rcu_dereference(nf_nat_rtsp_hook_expectfn);
+ if(nf_nat_rtsp_expectfn && ct->master->status & IPS_NAT_MASK) {
+ nf_nat_rtsp_expectfn(ct,exp);
+ }
+}
+
+/*** conntrack functions ***/
+
+/* outbound packet: client->server */
+
+static inline int
+help_out(struct sk_buff *skb, unsigned char *rb_ptr, unsigned int datalen,
+ struct nf_conn *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 nf_conntrack_expect *exp;
+
+ __be16 be_loport;
+
+ typeof(nf_nat_rtsp_hook) nf_nat_rtsp;
+
+ 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 */
+ pr_debug("found a setup message\n");
+
+ off = 0;
+ if(translen) {
+ rtsp_parse_transport(pdata+transoff, translen, &expinfo);
+ }
+
+ if (expinfo.loport == 0) {
+ pr_debug("no udp transports found\n");
+ continue; /* no udp transports found */
+ }
+
+ pr_debug("udp transport found, ports=(%d,%hu,%hu)\n",
+ (int)expinfo.pbtype, expinfo.loport, expinfo.hiport);
+
+ exp = nf_ct_expect_alloc(ct);
+ if (!exp) {
+ ret = NF_DROP;
+ goto out;
+ }
+
+ be_loport = htons(expinfo.loport);
+
+ nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
+ &ct->tuplehash[!dir].tuple.src.u3, &ct->tuplehash[!dir].tuple.dst.u3,
+ IPPROTO_UDP, NULL, &be_loport);
+
+ exp->master = ct;
+
+ exp->expectfn = expected;
+ exp->flags = 0;
+
+ if (expinfo.pbtype == pb_range) {
+ pr_debug("Changing expectation mask to handle multiple ports\n");
+ //exp->mask.dst.u.udp.port = 0xfffe;
+ }
+
+ pr_debug("expect_related %pI4:%u-%pI4:%u\n",
+ &exp->tuple.src.u3.ip,
+ ntohs(exp->tuple.src.u.udp.port),
+ &exp->tuple.dst.u3.ip,
+ ntohs(exp->tuple.dst.u.udp.port));
+
+ nf_nat_rtsp = rcu_dereference(nf_nat_rtsp_hook);
+ if (nf_nat_rtsp && ct->status & IPS_NAT_MASK)
+ /* pass the request off to the nat helper */
+ ret = nf_nat_rtsp(skb, ctinfo, hdrsoff, hdrslen, &expinfo, exp);
+ else if (nf_ct_expect_related(exp) != 0) {
+ pr_info("nf_conntrack_expect_related failed\n");
+ ret = NF_DROP;
+ }
+ nf_ct_expect_put(exp);
+ goto out;
+ }
+out:
+
+ return ret;
+}
+
+
+static inline int
+help_in(struct sk_buff *skb, size_t pktlen,
+ struct nf_conn* ct, enum ip_conntrack_info ctinfo)
+{
+ return NF_ACCEPT;
+}
+
+static int help(struct sk_buff *skb, unsigned int protoff,
+ struct nf_conn *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) {
+ pr_debug("conntrackinfo = %u\n", ctinfo);
+ return NF_ACCEPT;
+ }
+
+ /* Not whole TCP header? */
+ th = skb_header_pointer(skb,protoff, sizeof(_tcph), &_tcph);
+
+ if (!th)
+ return NF_ACCEPT;
+
+ /* No data ? */
+ dataoff = protoff + th->doff*4;
+ datalen = skb->len - dataoff;
+ if (dataoff >= skb->len)
+ return NF_ACCEPT;
+
+ spin_lock_bh(&rtsp_buffer_lock);
+ rb_ptr = skb_header_pointer(skb, dataoff,
+ skb->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(skb, rb_ptr, datalen, ct, ctinfo);
+ break;
+ case IP_CT_DIR_REPLY:
+ pr_debug("IP_CT_DIR_REPLY\n");
+ /* inbound packet: server->client */
+ ret = NF_ACCEPT;
+ break;
+ }
+
+ spin_unlock_bh(&rtsp_buffer_lock);
+
+ return ret;
+}
+
+static struct nf_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++) {
+ pr_debug("unregistering port %d\n", ports[i]);
+ nf_conntrack_helper_unregister(&rtsp_helpers[i]);
+ }
+ kfree(rtsp_buffer);
+}
+
+static int __init
+init(void)
+{
+ int i, ret;
+ struct nf_conntrack_helper *hlpr;
+ char *tmpname;
+
+ printk("nf_conntrack_rtsp v" IP_NF_RTSP_VERSION " loading\n");
+
+ if (max_outstanding < 1) {
+ printk("nf_conntrack_rtsp: max_outstanding must be a positive integer\n");
+ return -EBUSY;
+ }
+ if (setup_timeout < 0) {
+ printk("nf_conntrack_rtsp: setup_timeout must be a positive integer\n");
+ return -EBUSY;
+ }
+
+ rtsp_exp_policy.max_expected = max_outstanding;
+ rtsp_exp_policy.timeout = setup_timeout;
+
+ 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 nf_conntrack_helper));
+ hlpr->tuple.src.l3num = AF_INET;
+ 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->expect_policy = &rtsp_exp_policy;
+ 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;
+
+ pr_debug("port #%d: %d\n", i, ports[i]);
+
+ ret = nf_conntrack_helper_register(hlpr);
+
+ if (ret) {
+ printk("nf_conntrack_rtsp: ERROR registering port %d\n", ports[i]);
+ fini();
+ return -EBUSY;
+ }
+ num_ports++;
+ }
+ return 0;
+}
+
+module_init(init);
+module_exit(fini);
+
+EXPORT_SYMBOL(nf_nat_rtsp_hook_expectfn);
+
--- /dev/null
+++ b/extensions/rtsp/nf_conntrack_rtsp.h
@@ -0,0 +1,63 @@
+/*
+ * RTSP extension for IP connection tracking.
+ * (C) 2003 by Tom Marshall <tmarshall at 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 (*nf_nat_rtsp_hook)(struct sk_buff *skb,
+ enum ip_conntrack_info ctinfo,
+ unsigned int matchoff, unsigned int matchlen,
+ struct ip_ct_rtsp_expect *prtspexp,
+ struct nf_conntrack_expect *exp);
+
+extern void (*nf_nat_rtsp_hook_expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp);
+
+#define RTSP_PORT 554
+
+#endif /* __KERNEL__ */
+
+#endif /* _IP_CONNTRACK_RTSP_H */
--- /dev/null
+++ b/extensions/rtsp/nf_nat_rtsp.c
@@ -0,0 +1,491 @@
+/*
+ * RTSP extension for TCP NAT alteration
+ * (C) 2003 by Tom Marshall <tmarshall at 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 nf_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 <net/tcp.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include "nf_conntrack_rtsp.h"
+#include <net/netfilter/nf_conntrack_expect.h>
+
+#include <linux/inet.h>
+#include <linux/ctype.h>
+#define NF_NEED_STRNCASECMP
+#define NF_NEED_STRTOU16
+#include "netfilter_helpers.h"
+#define NF_NEED_MIME_NEXTLINE
+#include "netfilter_mime.h"
+
+#include "../compat_xtables.h"
+
+#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 at 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 = ip_hdr(skb);
+ struct tcphdr* tcph = (void *)iph + ip_hdrlen(skb);
+
+ *pptcpdata = (char*)tcph + tcph->doff*4;
+ *ptcpdatalen = ((char*)skb_transport_header(skb) + skb->len) - *pptcpdata;
+}
+
+/*** nat functions ***/
+
+/*
+ * Mangle the "Transport:" header:
+ * - Replace all occurences of "client_port=<spec>"
+ * - Handle destination parameter
+ *
+ * In:
+ * ct, ctinfo = conntrack context
+ * skb = 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 nf_conntrack_expect* exp,
+ struct ip_ct_rtsp_expect* prtspexp,
+ struct sk_buff* skb, 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 nf_conn *ct = exp->master;
+ struct nf_conntrack_tuple *t;
+
+ char szextaddr[15+1];
+ uint extaddrlen;
+ int is_stun;
+
+ get_skb_tcpdata(skb, &ptcp, &tcplen);
+ ptran = ptcp+tranoff;
+
+ if (tranoff+tranlen > tcplen || tcplen-tranoff < tranlen ||
+ tranlen < 10 || !iseol(ptran[tranlen-1]) ||
+ nf_strncasecmp(ptran, "Transport:", 10) != 0)
+ {
+ pr_info("sanity check failed\n");
+ return 0;
+ }
+ off += 10;
+ SKIP_WSPACE(ptcp+tranoff, tranlen, off);
+
+ newip = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip;
+ t = &exp->tuple;
+ t->dst.u3.ip = newip;
+
+ extaddrlen = extip ? sprintf(szextaddr, "%pI4", &extip)
+ : sprintf(szextaddr, "%pI4", &newip);
+ pr_debug("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 (nf_ct_expect_related(exp) == 0)
+ {
+ pr_debug("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 (nf_ct_expect_related(exp) == 0)
+ {
+ hiport = loport + 1; //~exp->mask.dst.u.udp.port;
+ pr_debug("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 (nf_ct_expect_related(exp) == 0)
+ {
+ pr_debug("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 (nf_ct_expect_related(exp) == 0)
+ {
+ pr_debug("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 (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
+ off, diff, NULL, 0))
+ {
+ /* mangle failed, all we can do is bail */
+ nf_ct_unexpect_related(exp);
+ return 0;
+ }
+ get_skb_tcpdata(skb, &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)
+ {
+ pr_debug("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 (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
+ origoff, origlen, rbuf, rbuflen))
+ {
+ /* mangle failed, all we can do is bail */
+ nf_ct_unexpect_related(exp);
+ return 0;
+ }
+ get_skb_tcpdata(skb, &ptcp, &tcplen);
+ ptran = ptcp+tranoff;
+ tranlen -= diff;
+ nextparamoff -= diff;
+ nextfieldoff -= diff;
+ }
+ }
+
+ off = nextfieldoff;
+ }
+
+ off = nextparamoff;
+ }
+
+ return 1;
+}
+
+static uint
+help_out(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
+ unsigned int matchoff, unsigned int matchlen, struct ip_ct_rtsp_expect* prtspexp,
+ struct nf_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(skb, &ptcp, &tcplen);
+ hdrsoff = matchoff;//exp->seq - ntohl(tcph->seq);
+ hdrslen = matchlen;
+ off = hdrsoff;
+ pr_debug("NAT rtsp help_out\n");
+
+ while (nf_mime_nextline(ptcp, hdrsoff+hdrslen, &off, &lineoff, &linelen))
+ {
+ if (linelen == 0)
+ {
+ break;
+ }
+ if (off > hdrsoff+hdrslen)
+ {
+ pr_info("!! overrun !!");
+ break;
+ }
+ pr_debug("hdr: len=%u, %.*s", linelen, (int)linelen, ptcp+lineoff);
+
+ if (nf_strncasecmp(ptcp+lineoff, "Transport:", 10) == 0)
+ {
+ uint oldtcplen = tcplen;
+ pr_debug("hdr: Transport\n");
+ if (!rtsp_mangle_tran(ctinfo, exp, prtspexp, skb, lineoff, linelen))
+ {
+ pr_debug("hdr: Transport mangle failed");
+ break;
+ }
+ get_skb_tcpdata(skb, &ptcp, &tcplen);
+ hdrslen -= (oldtcplen-tcplen);
+ off -= (oldtcplen-tcplen);
+ lineoff -= (oldtcplen-tcplen);
+ linelen -= (oldtcplen-tcplen);
+ pr_debug("rep: len=%u, %.*s", linelen, (int)linelen, ptcp+lineoff);
+ }
+ }
+
+ return NF_ACCEPT;
+}
+
+static unsigned int
+help(struct sk_buff *skb, enum ip_conntrack_info ctinfo,
+ unsigned int matchoff, unsigned int matchlen, struct ip_ct_rtsp_expect* prtspexp,
+ struct nf_conntrack_expect* exp)
+{
+ int dir = CTINFO2DIR(ctinfo);
+ int rc = NF_ACCEPT;
+
+ switch (dir)
+ {
+ case IP_CT_DIR_ORIGINAL:
+ rc = help_out(skb, ctinfo, matchoff, matchlen, prtspexp, exp);
+ break;
+ case IP_CT_DIR_REPLY:
+ pr_debug("unmangle ! %u\n", ctinfo);
+ /* XXX: unmangle */
+ rc = NF_ACCEPT;
+ break;
+ }
+ //UNLOCK_BH(&ip_rtsp_lock);
+
+ return rc;
+}
+
+static void expected(struct nf_conn* ct, struct nf_conntrack_expect *exp)
+{
+ struct nf_nat_ipv4_multi_range_compat mr;
+ u_int32_t newdstip, newsrcip, newip;
+
+ struct nf_conn *master = ct->master;
+
+ newdstip = master->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
+ newsrcip = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
+ //FIXME (how to port that ?)
+ //code from 2.4 : newip = (HOOK2MANIP(hooknum) == NF_NAT_MANIP_SRC) ? newsrcip : newdstip;
+ newip = newdstip;
+
+ pr_debug("newsrcip=%pI4, newdstip=%pI4, newip=%pI4\n",
+ &newsrcip, &newdstip, &newip);
+
+ mr.rangesize = 1;
+ // We don't want to manip the per-protocol, just the IPs.
+ mr.range[0].flags = NF_NAT_RANGE_MAP_IPS;
+ mr.range[0].min_ip = mr.range[0].max_ip = newip;
+
+ nf_nat_setup_info(ct, &mr.range[0], NF_NAT_MANIP_DST);
+}
+
+
+static void __exit fini(void)
+{
+ nf_nat_rtsp_hook = NULL;
+ nf_nat_rtsp_hook_expectfn = NULL;
+ synchronize_net();
+}
+
+static int __init init(void)
+{
+ printk("nf_nat_rtsp v" IP_NF_RTSP_VERSION " loading\n");
+
+ BUG_ON(nf_nat_rtsp_hook);
+ nf_nat_rtsp_hook = help;
+ nf_nat_rtsp_hook_expectfn = &expected;
+
+ 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);
--- a/extensions/Kbuild
+++ b/extensions/Kbuild
@@ -35,6 +35,7 @@ obj-${build_lscan} += xt_lscan.o
obj-${build_pknock} += pknock/
obj-${build_psd} += xt_psd.o
obj-${build_quota2} += xt_quota2.o
+obj-${build_rtsp} += rtsp/
-include ${M}/*.Kbuild
-include ${M}/Kbuild.*
--- a/mconfig
+++ b/mconfig
@@ -26,3 +26,4 @@ build_lscan=m
build_pknock=m
build_psd=m
build_quota2=m
+build_rtsp=m
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