K2.6 patches and update.

[tomato.git] / release / src-rt / linux / linux-2.6 / net / netfilter / nf_conntrack_rtsp.c

/*
 * 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 <linux/netfilter/nf_conntrack_rtsp.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>

#include <linux/ctype.h>
#define MAX_SIMUL_SETUP 8 /* XXX: use max_outstanding */
#define INFOP(fmt, args...) printk(KERN_INFO "%s: %s: " fmt, __FILE__, __FUNCTION__ , ## args)
#if 0
#define DEBUGP(fmt, args...) printk(KERN_DEBUG "%s: %s: " fmt, __FILE__, __FUNCTION__ , ## args)
#else
#define DEBUGP(fmt, args...)
#endif

#define MAX_PORTS 8
static unsigned short ports[MAX_PORTS];
static int num_ports = 0;
static unsigned int max_outstanding __read_mostly = 8;
static unsigned int setup_timeout __read_mostly = 300;

MODULE_AUTHOR("Tom Marshall <tmarshall at real.com>");
MODULE_DESCRIPTION("RTSP connection tracking module");
MODULE_LICENSE("GPL");
module_param_array(ports, ushort, &num_ports, 0400);
MODULE_PARM_DESC(ports, "port numbers of RTSP servers");
module_param(max_outstanding, uint, 0400);
MODULE_PARM_DESC(max_outstanding, "max number of outstanding SETUP requests per RTSP session");
module_param(setup_timeout, uint, 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) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_rtsp_hook);

void (*nf_nat_rtsp_hook_expectfn)(struct nf_conn *ct, struct nf_conntrack_expect *exp) __read_mostly;
EXPORT_SYMBOL_GPL(nf_nat_rtsp_hook_expectfn);

/*
 * 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) {
                        DEBUGP("!! 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) {
                DEBUGP("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 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;
        typeof(nf_nat_rtsp_hook) nf_nat_rtsp;

        __be16 be_loport;

        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 = nf_conntrack_expect_alloc(ct);
                if (!exp) {
                        ret = NF_DROP;
                        goto out;
                }

                be_loport = htons(expinfo.loport);

                nf_conntrack_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, ct->tuplehash[!dir].tuple.src.l3num,
                        /* media stream source can be different from the RTSP server address */
                        // &ct->tuplehash[!dir].tuple.src.u3, &ct->tuplehash[!dir].tuple.dst.u3,
                        NULL, &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) {
                        DEBUGP("Changing expectation mask to handle multiple ports\n");
                        exp->mask.dst.u.udp.port  = 0xfffe;
                        //exp->mask.src.u.udp.port  = 0xfffe;
                }

                DEBUGP("expect_related %u.%u.%u.%u:%u-%u.%u.%u.%u:%u\n",
                       NIPQUAD(exp->tuple.src.u3.ip),
                       ntohs(exp->tuple.src.u.udp.port),
                       NIPQUAD(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_conntrack_expect_related(exp) != 0) {
                        DEBUGP("nf_conntrack_expect_related failed\n");
                        ret  = NF_DROP;
                }
                nf_conntrack_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) {
                DEBUGP("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:
                DEBUGP("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] __read_mostly;
static char rtsp_names[MAX_PORTS][sizeof("rtsp-65535")] __read_mostly;

/* This function is intentionally _NOT_ defined as __exit */
static void
fini(void)
{
        int i;
        for (i = 0; i < num_ports; i++) {
                if (rtsp_helpers[i].me == NULL)
                        continue;
                DEBUGP("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;
        }

        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.l3num = 0xFFFF;
                hlpr->mask.src.u.tcp.port = htons(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;

                DEBUGP("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);