tap.cc

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/*
 * Copyright (c) 1997, 1998 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 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/emulate/tap.cc,v 1.14 2001/05/15 21:19:27 alefiyah Exp $ (UCB)";
#endif

#include "tap.h"

static class TapAgentClass : public TclClass {
 public:
        TapAgentClass() : TclClass("Agent/Tap") {}
        TclObject* create(int, const char*const*) {
                return (new TapAgent());
        }
} class_tap_agent;

TapAgent::TapAgent() : Agent(PT_LIVE), net_(NULL)
{
        bind("maxpkt_", &maxpkt_);
}

//
// link in a network to the agent.  Assumes net_ is non-zero
//
int
TapAgent::linknet()
{
        int mode = net_->mode();
        int rchan = net_->rchannel();
        int wchan = net_->schannel();

        unlink();
        if (mode == O_RDONLY || mode == O_RDWR) {
                // reading enabled?
                if (rchan < 0) {
                        fprintf(stderr,
                "TapAgent(%s): network %s not open for reading (mode:%d)\n",
                            name(), net_->name(), mode);
                        return (TCL_ERROR);
                }
                link(rchan, TCL_READABLE);
                TDEBUG3("TapAgent(%s): linked sock %d as READABLE\n",
                        name(), rchan);
        } else if (mode != O_WRONLY) {
                if (mode == -1) {
                        fprintf(stderr,
                           "TapAgent(%s): Network(%s) not opened properly.\n",
                                name(), net_->name());
                        fprintf(stderr,
                           "(choose: readonly, readwrite, or writeonly)\n");
                } else {
                        fprintf(stderr,
                            "TapAgent(%s): unknown mode %d in Network(%s)\n",
                                name(), mode, net_->name());
                }
                return (TCL_ERROR);
        }

        if (mode == O_WRONLY || mode == O_RDWR) {
                // writing enabled?
                if (wchan < 0) {
                        fprintf(stderr,
                        "TapAgent(%s): network %s not open for writing\n",
                            name(), net_->name());
                        return (TCL_ERROR);
                }
        }
        return (TCL_OK);
}

int
TapAgent::command(int argc, const char*const* argv)
{
        Tcl& tcl = Tcl::instance();

        if (argc == 2) {
                if (strcmp(argv[1], "network") == 0) {
                        tcl.result(name());
                        return(TCL_OK);
                } 
        }
        if (argc == 3) {
                if (strcmp(argv[1], "network") == 0) {
                        net_ = (Network *)TclObject::lookup(argv[2]);
                        if (net_ != 0) {
                                return(linknet());
                        } else {
                                fprintf(stderr,
                                "TapAgent(%s): unknown network %s\n",
                                    name(), argv[2]);
                                return (TCL_ERROR);
                        }
                        return(TCL_OK);
                }       
        }
        return (Agent::command(argc, argv));
}

/*
 * Receive a packet off the network and inject into the simulation.
 */
void
TapAgent::recvpkt()
{

        if (net_->mode() != O_RDWR && net_->mode() != O_RDONLY) {
                fprintf(stderr,
                  "TapAgent(%s): recvpkt called while in write-only mode!\n",
                  name());
                return;
        }

        if (maxpkt_ <= 0) {
                fprintf(stderr,
                  "TapAgent(%s): recvpkt: maxpkt_ value too low (%d)\n",
                  name(), maxpkt_);
                return;
        }

        // allocate packet and a data payload
        Packet* p = allocpkt(maxpkt_);

        // fill up payload
        sockaddr addr;  // not really used (yet)
        double tstamp;
        int cc = net_->recv(p->accessdata(), maxpkt_, addr, tstamp);
        if (cc <= 0) {
                if (cc < 0) {
                        perror("recv");
                }
                Packet::free(p);
                return;
        }

        TDEBUG4("%f: Tap(%s): recvpkt, cc:%d\n", now(), name(), cc);

        // inject into simulator
        hdr_cmn* ch = HDR_CMN(p);
        ch->size() = cc;

        /*
         * if the time-stamp on the pkt is sufficiently far in the future,
         * put it in the scheduler instead of forwarding it immediately.
         * This can happen if we are pulling packet from a trace file
         * and we don't want them to be dispatched until later
         *
         * this agent assumes that the time stamps are in absolute
         * time, so adjust it to relative time here
         */

        double when = tstamp - now();

        if (when > 0.0) {
                TDEBUG5("%f: Tap(%s): DEFERRED PACKET %f secs, uid: %d\n",
                        now(), name(), when, p->uid_);
                ch->timestamp() = when;
                Scheduler::instance().schedule(target_, p, when);
        } else {
                TDEBUG4("%f: Tap(%s): recvpkt, writing to target: %s\n",
                        now(), name(), target_->name());
                ch->timestamp() = now();
                target_->recv(p);
        }
        return;
}

void
TapAgent::dispatch(int)
{
        /*
         * Just process one packet.  We could put a loop here
         * but instead we allow the dispatcher to call us back
         * if there is a queue in the socket buffer; this allows
         * other events to get a chance to slip in...
         */
#ifdef notdef
Scheduler::instance().sync();   // sim clock gets set to now
#endif
        recvpkt();
}

/*
 * SIM -> Live
 *
 * Receive a packet from the simulation and inject into the network.
 * if there is no network attached, call Connector::drop() to send
 * to drop target
 */

void
TapAgent::recv(Packet* p, Handler*)
{
        (void) sendpkt(p);
        Packet::free(p);
        return;
}

int
TapAgent::sendpkt(Packet* p)
{
        if (net_->mode() != O_RDWR && net_->mode() != O_WRONLY) {
                fprintf(stderr,
                    "TapAgent(%s): sendpkt called while in read-only mode!\n",
                    name());
                return (-1);
        }

        // send packet into the live network
        hdr_cmn* hc = HDR_CMN(p);
        if (net_ == NULL) {
                fprintf(stderr,
                 "TapAgent(%s): sendpkt attempted with NULL net\n",
                 name());
                drop(p);
                return (-1);
        }
        if (net_->send(p->accessdata(), hc->size()) < 0) {
                fprintf(stderr,
                    "TapAgent(%s): sendpkt (%p, %d): %s\n",
                    name(), p->accessdata(), hc->size(), strerror(errno));
                return (-1);
                        
        }
        TDEBUG3("TapAgent(%s): sent packet (sz: %d)\n",
                name(), hc->size());
        return 0;
}

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