rtp.cc

Go to the documentation of this file.

/* -*-  Mode:C++; c-basic-offset:8; tab-width:8; indent-tabs-mode:t -*- */
/*
 * Copyright (c) 1997 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 MASH Research
 *  Group at the University of California Berkeley.
 * 4. Neither the name of the University nor of the Research Group 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.
 */

#ifndef lint
static const char rcsid[] =
    "@(#) $Header: /nfs/jade/vint/CVSROOT/ns-2/apps/rtp.cc,v 1.27 2005/08/22 05:08:32 tomh Exp $";
#endif


#include <stdlib.h>

#include "config.h"
#include "agent.h"
#include "random.h"
#include "rtp.h"

int hdr_rtp::offset_;

class RTPHeaderClass : public PacketHeaderClass {
public: 
        RTPHeaderClass() : PacketHeaderClass("PacketHeader/RTP",
                         sizeof(hdr_rtp)) {
        bind_offset(&hdr_rtp::offset_);
    }
} class_rtphdr;

static class RTPAgentClass : public TclClass {
public:
    RTPAgentClass() : TclClass("Agent/RTP") {}
    TclObject* create(int, const char*const*) {
        return (new RTPAgent());
    }
} class_rtp_agent;

RTPAgent::RTPAgent() : Agent(PT_RTP), session_(0), lastpkttime_(-1e6), 
    running_(0), rtp_timer_(this)
{
    bind("seqno_", &seqno_);
    bind_time("interval_", &interval_);
    bind("packetSize_", &size_);
    bind("maxpkts_", &maxpkts_);
    bind("random_", &random_);
}

void RTPAgent::start()
{
        running_ = 1;
        sendpkt();
        rtp_timer_.resched(interval_);
}

void RTPAgent::stop()
{
        rtp_timer_.force_cancel();
        finish();
}

void RTPAgent::sendmsg(int nbytes, const char* /*flags*/)
{
        Packet *p;
        int n;

    assert (size_ > 0);

        if (++seqno_ < maxpkts_) {
        n = nbytes / size_;

                if (nbytes == -1) {
                        start();
                        return;
                }
                while (n-- > 0) {
                        p = allocpkt();
                        hdr_rtp* rh = hdr_rtp::access(p);
                        rh->seqno() = seqno_;
                        target_->recv(p);
                }
                n = nbytes % size_;
                if (n > 0) {
                        p = allocpkt();
                        hdr_rtp* rh = hdr_rtp::access(p);
                        rh->seqno() = seqno_;
                        target_->recv(p);
                }
                idle();
        } else {
                finish();
                // xxx: should we deschedule the timer here? */
        };
}

void RTPAgent::timeout(int) 
{
    if (running_) {
        sendpkt();
        if (session_)
            session_->localsrc_update(size_);
        double t = interval_;
        if (random_)
            /* add some zero-mean white noise */
            t += interval_ * Random::uniform(-0.5, 0.5);
        rtp_timer_.resched(t);
    }
}

/*
 * finish() is called when we must stop (either by request or because
 * we're out of packets to send.
 */
void RTPAgent::finish()
{
        running_ = 0;
        Tcl::instance().evalf("%s done", this->name());
}

void RTPAgent::advanceby(int delta)
{
        maxpkts_ += delta;
        if (seqno_ < maxpkts_ && !running_)
                start();
}               


void RTPAgent::recv(Packet* p, Handler*)
{
    if (session_)
        session_->recv(p, 0);
    else
        Packet::free(p);
}

int RTPAgent::command(int argc, const char*const* argv)
{
    if (argc == 2) {
        if (strcmp(argv[1], "rate-change") == 0) {
            rate_change();
            return (TCL_OK);
        } else if (strcmp(argv[1], "start") == 0) {
                        start();
                        return (TCL_OK);
                } else if (strcmp(argv[1], "stop") == 0) {
                        stop();
                        return (TCL_OK);
                }
    } else if (argc == 3) {
        if (strcmp(argv[1], "session") == 0) {
            session_ = (RTPSession*)TclObject::lookup(argv[2]);
            return (TCL_OK);
        } else if (strcmp(argv[1], "advance") == 0) {
                        int newseq = atoi(argv[2]);
                        advanceby(newseq - seqno_);
                        return (TCL_OK); 
                } else if (strcmp(argv[1], "advanceby") == 0) {
                        advanceby(atoi(argv[2]));
                        return (TCL_OK);
                }       
    }
    return (Agent::command(argc, argv));
}

/* 
 * We modify the rate in this way to get a faster reaction to the a rate
 * change since a rate change from a very low rate to a very fast rate may 
 * take an undesireably long time if we have to wait for timeout at the old
 * rate before we can send at the new (faster) rate.
 */
void RTPAgent::rate_change()
{
    rtp_timer_.force_cancel();
    
    double t = lastpkttime_ + interval_;
    
    double now = Scheduler::instance().clock();
    if ( t > now)
        rtp_timer_.resched(t - now);
    else {
        sendpkt();
        rtp_timer_.resched(interval_);
    }
}

void RTPAgent::sendpkt()
{
    Packet* p = allocpkt();
    lastpkttime_ = Scheduler::instance().clock();
    makepkt(p);
    target_->recv(p, (Handler*)0);
}

void RTPAgent::makepkt(Packet* p)
{
    hdr_rtp *rh = hdr_rtp::access(p);
    /* Fill in srcid_ and seqno */
    rh->seqno() = seqno_++;
    rh->srcid() = session_ ? session_->srcid() : 0;
}

void RTPTimer::expire(Event* /*e*/) {
        a_->timeout(0);
}

---