/*-
 * Copyright (c) 1993-1994 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Berkeley and the Network Research Group at
 *      Lawrence Berkeley Laboratory.
 * 4. Neither the name of the University nor of the Laboratory may be used
 *    to endorse or promote products derived from this software without
 *    specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
static const char rcsid[] =
    "@(#) $Header: session.cc,v 1.100 96/04/01 15:45:56 mccanne Exp $ (LBL)";

#include "config.h"
#include <math.h>
#include <errno.h>
#include <string.h>
#ifdef WIN32
extern "C" int getpid();
#endif
#include "source.h"
#include "Tcl.h"
#include "media-timer.h"
#include "crypt.h"
#include "timer.h"
#include "ntp-time.h"
#include "session.h"

static class SessionMatcher : public Matcher {
    public:
	SessionMatcher() : Matcher("session") {}
	TclObject* match(const char* id) {
		if (strcmp(id, "audio/rtp") == 0)
			return (new AudioSessionManager);
		else if (strcmp(id, "video/rtp") == 0)
			return (new VideoSessionManager);
		return (0);
	}
} session_matcher;

int VideoSessionManager::check_format(int fmt) const
{
	switch(fmt) {
	case RTP_PT_CELLB:
	case RTP_PT_JPEG:
	case RTP_PT_CUSEEME:
	case RTP_PT_NV:
	case RTP_PT_CPV:
	case RTP_PT_H261:
	case RTP_PT_BVC:
	case RTP_PT_H261_COMPAT:/*XXX*/
		return (1);
	}
	return (0);
}

int AudioSessionManager::check_format(int fmt) const
{
	switch (fmt) {
	case RTP_PT_PCMU:
	case RTP_PT_CELP:
	case RTP_PT_GSM:
	case RTP_PT_DVI:
	case RTP_PT_LPC:
		return (1);
	}
	return (0);
}

static SessionManager* manager;

void
adios()
{
	if (SourceManager::instance().localsrc() != 0)
		manager->send_bye();
	exit(0);
}

void ReportTimer::timeout()
{
	sm_.send_report();
}

void DataHandler::dispatch(int)
{
	sm_.recv(this);
}

void CtrlHandler::dispatch(int)
{
	sm_.recv(this);
}

SessionManager::SessionManager()
	: dh_(*this), ch_(*this), rt_(*this),
	  badversion_(0), badoptions_(0), badfmt_(0), badext_(0), nrunt_(0),
	  last_np_(0),
	  sdes_seq_(0),
	  rtcp_inv_bw_(0.),
	  rtcp_avg_size_(128.),
	  confid_(-1)
{
	/*XXX*/
	manager = this;

	/*XXX*/
	pktbuf_ = new u_char[2 * RTP_MTU];

	/*
	 * schedule a timer for our first report using half the
	 * min rtcp interval.  This gives us some time before
	 * our first report to learn about other sources so our
	 * next report interval will account for them.  The avg
	 * rtcp size was initialized to 128 bytes which is
	 * conservative (it assumes everyone else is generating
	 * SRs instead of RRs).
	 */
	double rint = rtcp_avg_size_ * rtcp_inv_bw_;
	if (rint < RTCP_MIN_RPT_TIME / 2. * 1000.)
		rint = RTCP_MIN_RPT_TIME / 2. * 1000.;
	rint_ = rint;
	rt_.msched(int(fmod(double(random()), rint) + rint * .5 + .5));
}

SessionManager::~SessionManager()
{
	delete pktbuf_;
}

u_int32_t SessionManager::alloc_srcid(u_int32_t addr) const
{
	timeval tv;
	::gettimeofday(&tv, 0);
	u_int32_t srcid = u_int32_t(tv.tv_sec + tv.tv_usec);
	srcid += (u_int32_t)getuid();
	srcid += (u_int32_t)getpid();
	srcid += addr;
	return (srcid);
}

extern char* onestat(char* cp, const char* name, u_long v);

char* SessionManager::stats(char* cp) const
{
	cp = onestat(cp, "Bad-RTP-version", badversion_);
	cp = onestat(cp, "Bad-RTPv1-options", badoptions_);
	cp = onestat(cp, "Bad-Payload-Format", badfmt_);
	cp = onestat(cp, "Bad-RTP-Extension", badext_);
	cp = onestat(cp, "Runts", nrunt_);
	Crypt* p = dh_.net()->crypt();
	if (p != 0) {
		cp = onestat(cp, "Crypt-Bad-Length", p->badpktlen());
		cp = onestat(cp, "Crypt-Bad-P-Bit", p->badpbit());
	}
	/*XXX*/
	if (ch_.net() != 0) {
		Crypt* p = ch_.net()->crypt();
		if (p != 0) {
			cp = onestat(cp, "Crypt-Ctrl-Bad-Length", p->badpktlen());
			cp = onestat(cp, "Crypt-Ctrl-Bad-P-Bit", p->badpbit());
		}
	}
	*--cp = 0;
	return (cp);
}

int SessionManager::command(int argc, const char*const* argv)
{
	Tcl& tcl = Tcl::instance();
	char* cp = tcl.buffer();
	if (argc == 2) {
		if (strcmp(argv[1], "active") == 0) {
			SourceManager::instance().sortactive(cp);
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "local-addr-heuristic") == 0) {
			strcpy(cp, intoa(LookupLocalAddr()));
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "stats") == 0) {
			stats(cp);
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "nb") == 0) {
			sprintf(cp, "%u", 8 * nb_);
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "nf") == 0) {
			sprintf(cp, "%u", nf_);
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "np") == 0 ||
		    strcmp(argv[1], "ns") == 0) {
			sprintf(cp, "%u", np_);
			tcl.result(cp);
			return (TCL_OK);
		}
	} else if (argc == 3) {
		if (strcmp(argv[1], "name") == 0) {
			Source* s = SourceManager::instance().localsrc();
			s->sdes(RTCP_SDES_NAME, argv[2]);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "email") == 0) {
			Source* s = SourceManager::instance().localsrc();
			s->sdes(RTCP_SDES_EMAIL, argv[2]);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "random-srcid") == 0) {
			sprintf(cp, "%u", alloc_srcid(inet_addr(argv[2])));
			tcl.result(cp);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "data-net") == 0) {
			dh_.net((Network*)TclObject::lookup(argv[2]));
			return (TCL_OK);
		}
		if (strcmp(argv[1], "ctrl-net") == 0) {
			ch_.net((Network*)TclObject::lookup(argv[2]));
			return (TCL_OK);
		}
		if (strcmp(argv[1], "max-bandwidth") == 0) {
			double bw = atof(argv[2]) / 8.;
			rtcp_inv_bw_ = 1. / (bw * RTCP_SESSION_BW_FRACTION);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "confid") == 0) {
			confid_ = atoi(argv[2]);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "data-bandwidth") == 0) {
			/*XXX assume value in range */
			bps(atoi(argv[2]));
			return (TCL_OK);
		}
		if (strcmp(argv[1], "mtu") == 0) {
			mtu_ = atoi(argv[2]);
			return (TCL_OK);
		}
		if (strcmp(argv[1], "loopback") == 0) {
			loopback_ = atoi(argv[2]);
			return (TCL_OK);
		}
	}
	return (Transmitter::command(argc, argv));
}

void SessionManager::transmit(pktbuf* pb)
{
	mh_.msg_iov = pb->iov;
	dh_.net()->sendmsg(mh_);
}

u_char* SessionManager::build_sdes_item(u_char* p, int code, Source& s)
{
	const char* value = s.sdes(code);
	if (value != 0) {
		int len = strlen(value);
		*p++ = code;
		*p++ = len;
		memcpy(p, value, len);
		p += len;
	}
	return (p);
}

int SessionManager::build_sdes(rtcphdr* rh, Source& ls)
{
	int flags = RTP_VERSION << 14 | 1 << 8 | RTCP_PT_SDES;
	rh->rh_flags = htons(flags);
	rh->rh_ssrc = ls.srcid();
	u_char* p = (u_char*)(rh + 1);
	p = build_sdes_item(p, RTCP_SDES_CNAME, ls);

	/*
	 * We always send a cname plus one other sdes
	 * There's a schedule for what we send sequenced by sdes_seq_:
	 *   - send 'email' every 0th & 4th packet
	 *   - send 'note' every 2nd packet
	 *   - send 'tool' every 6th packet
	 *   - send 'name' in all the odd slots
	 * (if 'note' is not the empty string, we switch the roles
	 *  of name & note)
	 */
	int nameslot, noteslot;
	const char* note = ls.sdes(RTCP_SDES_NOTE);
	if (note) {
		if (*note) {
			nameslot = RTCP_SDES_NOTE;
			noteslot = RTCP_SDES_NAME;
		} else {
			nameslot = RTCP_SDES_NAME;
			noteslot = RTCP_SDES_NOTE;
		}
	} else {
		nameslot = RTCP_SDES_NAME;
		noteslot = RTCP_SDES_NAME;
	}
	u_int seq = (++sdes_seq_) & 0x7;
	switch (seq) {

	case 0:  case 4:
		p = build_sdes_item(p, RTCP_SDES_EMAIL, ls);
		break;

	case 2:
		p = build_sdes_item(p, noteslot, ls);
		break;
	case 6:
		p = build_sdes_item(p, RTCP_SDES_TOOL, ls);
		break;
	default:
		p = build_sdes_item(p, nameslot, ls);
	}
	int len = p - (u_char*)rh;
	int pad = 4 - (len & 3);
	len += pad;
	rh->rh_len = htons((len >> 2) - 1);
	while (--pad >= 0)
		*p++ = 0;

	return (len);
}

void SessionManager::send_report()
{
	send_report(0);
}

void SessionManager::send_bye()
{
	send_report(1);
}

/*XXX check for buffer overflow*/
/*
 * Send an RTPv2 report packet.
 */
void SessionManager::send_report(int bye)
{
	SourceManager& sm = SourceManager::instance();
	Source& s = *sm.localsrc();
	rtcphdr* rh = (rtcphdr*)pktbuf_;
	rh->rh_ssrc = s.srcid();
	int flags = RTP_VERSION << 14;
	timeval now = unixtime();
	s.lts_ctrl(now);
	int we_sent = 0;
	rtcp_rr* rr;
	/*
	 * If we've sent data since our last sender report send a
	 * new report.  The MediaTimer check is to make sure we still
	 * have a grabber -- if not, we won't be able to interpret the
	 * media timestamps so there's no point in sending an SR.
	 */
	MediaTimer* mt = MediaTimer::instance();
	if (s.np() != last_np_ && mt) {
		last_np_ = s.np();
		we_sent = 1;
		flags |= RTCP_PT_SR;
		rtcp_sr* sr = (rtcp_sr*)(rh + 1);
		sr->sr_ntp = ntp64time(now);
		HTONL(sr->sr_ntp.upper);
		HTONL(sr->sr_ntp.lower);
		sr->sr_ts = htonl(mt->ref_ts());
		sr->sr_np = htonl(s.np());
		sr->sr_nb = htonl(s.nb());
		rr = (rtcp_rr*)(sr + 1);
	} else {
		flags |= RTCP_PT_RR;
		rr = (rtcp_rr*)(rh + 1);
	}
	int nrr = 0;
	int nsrc = 0;
	/*
	 * we don't want to inflate report interval if user has set
	 * the flag that causes all sources to be 'kept' so we
	 * consider sources 'inactive' if we haven't heard a control
	 * msg from them for ~32 reporting intervals.
	 */
	u_int inactive = u_int(rint_ * (32./1000.));
	if (inactive < 2)
		inactive = 2;
	for (Source* sp = sm.sources(); sp != 0; sp = sp->next_) {
		++nsrc;
		int received = sp->np() - sp->snp();
		if (received == 0) {
			if (u_int(now.tv_sec - sp->lts_ctrl().tv_sec) > inactive)
				--nsrc;
			continue;
		}
		sp->snp(sp->np());
		rr->rr_srcid = sp->srcid();
		int expected = sp->ns() - sp->sns();
		sp->sns(sp->ns());
		u_int32_t v;
		int lost = expected - received;
		if (lost <= 0)
			v = 0;
		else
			/* expected != 0 if lost > 0 */
			v = ((lost << 8) / expected) << 24;
		/* XXX should saturate on over/underflow */
		v |= (sp->ns() - sp->np()) & 0xffffff;
		rr->rr_loss = htonl(v);
		rr->rr_ehsr = htonl(sp->ehs());
		rr->rr_dv = (sp->handler() != 0) ? sp->handler()->delvar() : 0;
		rr->rr_lsr = htonl(sp->sts_ctrl());
		if (sp->lts_ctrl().tv_sec == 0)
			rr->rr_dlsr = 0;
		else {
			u_int32_t ntp_now = ntptime(now);
			rr->rr_dlsr = htonl(ntp_now - sp->lts_ctrl().tv_sec);
		}
		++rr;
		if (++nrr >= 31)
			break;
	}
	flags |= nrr << 8;
	rh->rh_flags = htons(flags);
	int len = (u_char*)rr - pktbuf_;
	rh->rh_len = htons((len >> 2) - 1);

	if (bye)
		len += build_bye((rtcphdr*)rr, s);
	else
		len += build_sdes((rtcphdr*)rr, s);

	ch_.send(pktbuf_, len);

	rtcp_avg_size_ += RTCP_SIZE_GAIN * (double(len + 28) - rtcp_avg_size_);

	/*
	 * compute the time to the next report.  we do this here
	 * because we need to know if there were any active sources
	 * during the last report period (nrr above) & if we were
	 * a source.  The bandwidth limit for rtcp traffic was set
	 * on startup from the session bandwidth.  It is the inverse
	 * of bandwidth (ie., ms/byte) to avoid a divide below.
	 */
	double ibw = rtcp_inv_bw_;
	if (nrr) {
		/* there were active sources */
		if (we_sent) {
			ibw *= 1./RTCP_SENDER_BW_FRACTION;
			nsrc = nrr;
		} else {
			ibw *= 1./RTCP_RECEIVER_BW_FRACTION;
			nsrc -= nrr;
		}
	}
	double rint = rtcp_avg_size_ * double(nsrc) * ibw;
	if (rint < RTCP_MIN_RPT_TIME * 1000.)
		rint = RTCP_MIN_RPT_TIME * 1000.;
	rint_ = rint;
	rt_.msched(int(fmod(double(random()), rint) + rint * .5 + .5));

	sm.CheckActiveSources(rint);
}

int SessionManager::build_bye(rtcphdr* rh, Source& ls)
{
	int flags = RTP_VERSION << 14 | 1 << 8 | RTCP_PT_BYE;
	rh->rh_flags = ntohs(flags);
	rh->rh_len = htons(1);
	rh->rh_ssrc = ls.srcid();
	return (8);
}

void SessionManager::recv(DataHandler* dh)
{
	u_int32_t addr;
	/* leave room in case we need to expand rtpv1 into an rtpv2 header */
	u_char* bp = &pktbuf_[4];
	int cc = dh->recv(bp, 2 * RTP_MTU - 4, addr);
	if (cc <= 0)
		return;

	rtphdr* rh = (rtphdr*)bp;
	int version = *(u_char*)rh >> 6;
	if (version != 2) {
		++badversion_;
		return;
	}
	bp += sizeof(*rh);
	cc -= sizeof(*rh);
	demux(rh, bp, cc, addr);
}

void SessionManager::demux(rtphdr* rh, u_char* bp, int cc, u_int32_t addr)
{
	if (cc < 0) {
		++nrunt_;
		return;
	}
	u_int32_t srcid = rh->rh_ssrc;
	int flags = ntohs(rh->rh_flags);
	if ((flags & RTP_X) != 0) {
		/*
		 * the minimal-control audio/video profile
		 * explicitly forbids extensions
		 */
		++badext_;
		return;
	}

	/*
	 * Check for illegal payload types.  Most likely this is
	 * a session packet arriving on the data port.
	 */
	int fmt = flags & 0x7f;
	if (!check_format(fmt)) {
		++badfmt_;
		return;
	}

	SourceManager& sm = SourceManager::instance();
	u_int16_t seqno = ntohs(rh->rh_seqno);
	Source* s = sm.demux(srcid, addr, seqno);
	if (s == 0)
		/*
		 * Takes a pair of validated packets before we will
		 * believe the source.  This prevents a runaway
		 * allocation of Source data structures for a
		 * stream of garbage packets.
		 */
		return;
	
	timeval now = unixtime();
	s->lts_data(now);
	s->sts_data(rh->rh_ts);

	int cnt = (flags >> 8) & 0xf;
	if (cnt > 0) {
		u_char* nh = (u_char*)rh + (cnt << 2);
		while (--cnt >= 0) {
			u_int32_t csrc = *(u_int32_t*)bp;
			bp += 4;
			Source* cs = sm.lookup(csrc, srcid, addr);
			cs->lts_data(now);
			cs->action();
		}
		/*XXX move header up so it's contiguous with data*/
		rtphdr hdr = *rh;
		rh = (rtphdr*)nh;
		*rh = hdr;
	} else
		s->action();

	/*
	 * This is a data packet.  If the source needs activation,
	 * or the packet format has changed, deal with this.
	 * Then, hand the packet off to the packet handler.
	 * XXX might want to be careful about flip-flopping
	 * here when format changes due to misordered packets
	 * (easy solution -- keep rtp seqno of last fmt change).
	 */
	PacketHandler* h = s->handler();
	if (h == 0)
		h = s->activate(fmt);
	else if (s->format() != fmt)
		h = s->change_format(fmt);

	/*
	 * XXX bit rate doesn't include rtpv1 options;
	 * but v1 is going away anyway.
	 */
	int dup = s->cs(seqno);
	s->np(1);
	s->nb(cc + sizeof(*rh));
	if (dup)
		return;
	if (flags & RTP_M)
		s->nf(1);

	int hlen = h->hdrlen();
	cc -= hlen;
	if (cc < 0) {
		s->runt(1);
		return;
	}
	if (!s->mute())
		h->recv(rh, bp + hlen, cc);
}

void SessionManager::parse_rr_records(u_int32_t, rtcp_rr*, int,
				      const u_char*, u_int32_t)
{
}
				      
void SessionManager::parse_sr(rtcphdr* rh, int flags, u_char*ep,
			      Source* ps, u_int32_t addr)
{
	rtcp_sr* sr = (rtcp_sr*)(rh + 1);
	Source* s;
	u_int32_t ssrc = rh->rh_ssrc;
	if (ps->srcid() != ssrc)
		s = SourceManager::instance().lookup(ssrc, ssrc, addr);
	else
		s = ps;

	s->lts_ctrl(unixtime());
	s->sts_ctrl(ntohl(sr->sr_ntp.upper) << 16 |
		    ntohl(sr->sr_ntp.lower) >> 16);

	int cnt = flags >> 8 & 0x1f;
	parse_rr_records(ssrc, (rtcp_rr*)(sr + 1), cnt, ep, addr);
}

void SessionManager::parse_rr(rtcphdr* rh, int flags, u_char* ep,
			      Source* ps, u_int32_t addr)
{
	Source* s;
	u_int32_t ssrc = rh->rh_ssrc;
	if (ps->srcid() != ssrc)
		s = SourceManager::instance().lookup(ssrc, ssrc, addr);
	else
		s = ps;

	s->lts_ctrl(unixtime());
	int cnt = flags >> 8 & 0x1f;
	parse_rr_records(ssrc, (rtcp_rr*)(rh + 1), cnt, ep, addr);
}

int SessionManager::sdesbody(u_int32_t* p, u_char* ep, Source* ps,
			     u_int32_t addr, u_int32_t ssrc)
{
	Source* s;
	u_int32_t srcid = *p;
	if (ps->srcid() != srcid)
		s = SourceManager::instance().lookup(srcid, ssrc, addr);
	else
		s = ps;
	if (s == 0)
		return (0);
	/*
	 * Note ctrl packet since we will never see any direct ctrl packets
	 * from a source through a mixer (and we don't want the source to
	 * time out).
	 */
	s->lts_ctrl(unixtime());

	u_char* cp = (u_char*)(p + 1);
	while (cp < ep) {
		char buf[256];

		u_int type = cp[0];
		if (type == 0) {
			/* end of chunk */
			return (((cp - (u_char*)p) >> 2) + 1);
		}
		u_int len = cp[1];
		u_char* eopt = cp + len + 2;
		if (eopt > ep)
			return (0);

		if (type >= RTCP_SDES_MIN && type <= RTCP_SDES_MAX) {
			memcpy(buf, (char*)&cp[2], len);
			buf[len] = 0;
			s->sdes(type, buf);
		} else
			/*XXX*/;

		cp = eopt;
	}
	return (0);
}

void SessionManager::parse_sdes(rtcphdr* rh, int flags, u_char* ep, Source* ps,
				u_int32_t addr, u_int32_t ssrc)
{
	int cnt = flags >> 8 & 0x1f;
	u_int32_t* p = (u_int32_t*)&rh->rh_ssrc;
	while (--cnt >= 0) {
		int n = sdesbody(p, ep, ps, addr, ssrc);
		if (n == 0)
			break;
		p += n;
	}
	if (cnt >= 0)
		ps->badsdes(1);
}

void SessionManager::parse_bye(rtcphdr* rh, int flags, u_char* ep, Source* ps)
{
	int cnt = flags >> 8 & 0x1f;
	u_int32_t* p = (u_int32_t*)&rh->rh_ssrc;

	while (--cnt >= 0) {
		if (p >= (u_int32_t*)ep) {
			ps->badbye(1);
			return;
		}
		Source* s;
		if (ps->srcid() != rh->rh_ssrc)
			s = SourceManager::instance().consult(*p);
		else
			s = ps;
		if (s != 0)
			s->lts_done(unixtime());
		++p;
	}
}

/*
 * Receive an rtcp packet (from the control port).
 */
void SessionManager::recv(CtrlHandler* ch)
{
	u_int32_t src;
	int cc = ch->recv(pktbuf_, 2 * RTP_MTU, src);
	if (cc <= 0)
		return;

	rtcphdr* rh = (rtcphdr*)pktbuf_;
	if (cc < int(sizeof(*rh))) {
		++nrunt_;
		return;
	}
	/*
	 * try to filter out junk: first thing in packet must be
	 * sr, rr or bye & version number must be correct.
	 */
	switch(ntohs(rh->rh_flags) & 0xc0ff) {
	case RTP_VERSION << 14 | RTCP_PT_SR:
	case RTP_VERSION << 14 | RTCP_PT_RR:
	case RTP_VERSION << 14 | RTCP_PT_BYE:
		break;
	default:
		/*
		 * XXX should further categorize this error -- it is
		 * likely that people mis-implement applications that
		 * don't put something other than SR,RR,BYE first.
		 */
		++badversion_;
		return;
	}
	/*
	 * at this point we think the packet's valid.  Update our average
	 * size estimator.  Also, there's valid ssrc so charge errors to it
	 */
	rtcp_avg_size_ += RTCP_SIZE_GAIN * (double(cc + 28) - rtcp_avg_size_);
	u_int32_t addr = src;

	/*
	 * First record in compount packet must be the ssrc of the
	 * sender of the packet.  Pull it out here so we can use
	 * it in the sdes parsing, since the sdes record doesn't
	 * contain the ssrc of the sender (in the case of mixers).
	 */
	u_int32_t ssrc = rh->rh_ssrc;
	Source* ps = SourceManager::instance().lookup(ssrc, ssrc, addr);
	if (ps == 0)
		return;

	/*
	 * Outer loop parses multiple RTCP records of a "compound packet".
	 * There is no framing between records.  Boundaries are implicit
	 * and the overall length comes from UDP.
	 */
	u_char* epack = (u_char*)rh + cc;
	while ((u_char*)rh < epack) {
		u_int len = (ntohs(rh->rh_len) << 2) + 4;
		u_char* ep = (u_char*)rh + len;
		if (ep > epack) {
			ps->badsesslen(1);
			return;
		}
		u_int flags = ntohs(rh->rh_flags);
		if (flags >> 14 != RTP_VERSION) {
			ps->badsessver(1);
			return;
		}
		switch (flags & 0xff) {

		case RTCP_PT_SR:
			parse_sr(rh, flags, ep, ps, addr);
			break;

		case RTCP_PT_RR:
			parse_rr(rh, flags, ep, ps, addr);
			break;

		case RTCP_PT_SDES:
			parse_sdes(rh, flags, ep, ps, addr, ssrc);
			break;

		case RTCP_PT_BYE:
			parse_bye(rh, flags, ep, ps);
			break;

		default:
			ps->badsessopt(1);
			break;
		}
		rh = (rtcphdr*)ep;
	}
}
