modules/up/src/Core/network/ICMProbe.cc

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FUNCTIONS

This source file includes following functions.
  1. icmprobeTimerHandler
  2. ICMProbe
  3. ICMProbe
  4. send
  5. handleTimer
  6. receive

//
// $Id: ICMProbe.cc,v 1.1.1.1 2000/03/10 16:32:19 engin Exp $
//
// Author(s): Ramesh Govindan

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

extern "C" {
#include <sys/types.h>
#include <netinet/in_systm.h>
#include <netinet/in.h>
#include <netinet/ip.h>
}

#include "util/Types.hh"
#include "util/Trail.hh"
#include "util/Handler.hh"
#include "util/Buffer.hh"
#include "sys/File.hh"
#include "sys/Pipe.hh"
#include "sys/Time.hh"
#include "sched/Timer.hh"
#include "sched/Dispatcher.hh"

#include "network/ICMProbe.hh"
#include "network/Headers.hh"
#include "network/Network.hh"

// Constants
static const unsigned char      UDPProtocol = 17;

// Locals
static TraceCode        traceICMProbe("net");
static TimeShort        maxWait(10, 0);
static unsigned int     probeNumber = 0x80000000;

static void
icmprobeTimerHandler(void* ptr,
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                   void*)
{
    ((ICMProbe*) ptr)->handleTimer();
}

ICMProbe::ICMProbe(Address* a,
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                   Handler& cb,
                   int hc,
                   Address* v)
   : ListNode()
{
    done = cb;
    to = *a;
    hopcount = hc;
    if (v) {
        via = *v;
    }
    timer = NULL;
    result = ICMProbeResultNone;
    residualHops = 0;
    network->pendingICMProbes.append(this);
    probeId = 0;
    lastRtt = InfiniteInterval;
    sent = 0;
}

ICMProbe::~ICMProbe()
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{
    network->pendingICMProbes.remove(this);
    if (timer) {
        delete timer;
    }
}

void
ICMProbe::send()
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{
    Handler     th(icmprobeTimerHandler, this);
    Handler     nh(NULL, NULL);
    Buffer*     buf;
    IP*         ip;
    IPOptLSRR*  ipopt;
    ICMP*       icmp;
    RawSocket*  raw;
    U32*        t;
    TimeLong    at;
    Address     srcaddr;

    responder.set(0);
    result = ICMProbeResultNone;
    sent++;
    network->icmprobesSent++;

    // Send packet
    raw = new RawSocket(nh, nh, RawSocketICMP);
    if (via.get()) {
        buf = new Buffer(sizeof(IP) + sizeof(IPOptLSRR) + sizeof(ICMP) + 8);
    } else {
        buf = new Buffer(sizeof(IP) + sizeof(ICMP) + 8);
    }
    buf->zeroFill();

    ip = (IP*) buf->contents;
    ip->headerLength = via.get() ? 
        (sizeof(IP) + sizeof(IPOptLSRR)) >> 2 :
         sizeof(IP) >> 2;
    ip->version = 4;
    ip->typeOfService = 0;
    ip->totalLength = (ip->headerLength << 2) + sizeof(ICMP);
    ip->identifier = 0;
    ip->fragmentOffset = 0;
    ip->timeToLive = hopcount;
    ip->protocol = IPPROTO_ICMP;
    ip->source = (network->interfaces.head())->address.get();
    ip->destination = (via.get()) ? via.get() : to.get();
    ip->hton();
    ip->checksum = 0;
    ip->checksum = network->cksum((U16*) ip, ip->headerLength << 2);

    if (via.get()) {
        IPOptLSRR*      lsrr;

        lsrr = (IPOptLSRR*) (ip + 1);
        lsrr->nullopt = IPOPT_NOP;
        lsrr->lsrropt = IPOPT_LSRR;
        lsrr->length = sizeof(U32) + 3;
        lsrr->pointer = IPOPT_MINOFF;
        lsrr->gateway = to.get();
        lsrr->hton();
        icmp = (ICMP*) (lsrr + 1);
    } else {
        icmp = (ICMP*) (ip + 1);
    }

    ASSERT(probeNumber != 0xffffffff);  // Wrap around
    probeNumber++;
    probeId = probeNumber;

    icmp->type = ICMPTypeEcho;
    icmp->code = 0;
    icmp->gateway = probeNumber;
    icmp->hton();
    icmp->checksum = 0;
    icmp->checksum = network->cksum((U16*) icmp, sizeof(ICMP) + 8);

    dispatcher.systemClock.sync();
    sentAt = dispatcher.systemClock;

    raw->sendTo(buf->contents, buf->size, to, 0);

    TRACE(traceICMProbe, "icmprobe to %s:%d\n", to.name(), hopcount);

    delete raw;
    delete buf;
    
    if (timer) {
        delete timer;
    }
    at = dispatcher.systemClock;
    at = at + maxWait;
    timer = new Timer(th, at);

    return;
}

void
ICMProbe::handleTimer()
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{
    TRACE(traceICMProbe, "icmprobe failed to %s\n", to.name());

    timer = NULL;
    network->icmprobesTimedOut++;
    done.callBack((void*) this);
    lastRtt = InfiniteInterval;
    return;
}

Boolean
ICMProbe::receive(IP* ip)
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{
    ICMP*               icmp;
    unsigned short      sum;
    IP*                 iip;
    int                 datalen;

    // Verify signature to see if it is for us
    icmp = (struct ICMP*) ((char*) ip + (ip->headerLength << 2));
    if (icmp->type != ICMPTypeTimeExceeded &&
        icmp->type != ICMPTypeDestinationUnreachable &&
        icmp->type != ICMPTypeEchoReply)
        return false;

    if (icmp->type == ICMPTypeTimeExceeded ||
        icmp->type == ICMPTypeDestinationUnreachable) {

       datalen = ip->totalLength - (ip->headerLength << 2) - sizeof(ICMP);
       if (datalen < sizeof(IP))
          return false;         // Malformed response, discard

       iip = (struct IP*) (icmp + 1);
       iip->ntoh();

       if (datalen < ((iip->headerLength << 2) + 2 * sizeof(unsigned long)))
          return false;         // Timestamp not there, discard

       if (iip->destination != to.get())
          return false;

       ICMP* icmpi = (ICMP*) (((char*) iip) + (iip->headerLength<<2));
       icmpi->ntoh();

       if (icmpi->gateway != probeNumber) // it is not the pkt we sent
          return false;
    }

    dispatcher.systemClock.sync();
    lastRtt = dispatcher.systemClock - sentAt;

    switch (icmp->type) {
    case ICMPTypeEchoReply:
       if (ip->source != to.get()) {
          return false;
       }
       if (icmp->gateway != probeNumber) {
          return false;
       }
        
       responder.set(ip->source);
       residualHops = 0;
       result = ICMProbeResultReachedNode;

       TRACE(traceICMProbe, "received icmprobe for %s:%d from %s\n",
             to.name(), hopcount, responder.name());
       done.callBack((void*) this);
       break;

    case ICMPTypeTimeExceeded:
       if (iip->timeToLive <= 1) {
          responder.set(ip->source);
          result = ICMProbeResultTimeExpired;
          TRACE(traceICMProbe, "received icmprobe for %s:%d from %s\n",
                to.name(), hopcount, responder.name());
       } else {
          responder.set(ip->source);
          ERROR("unexpected ttl %d in ICMP TimeExceeded from %s\n",
                iip->timeToLive, responder.name());
          result = ICMProbeResultDontCare;
       } 
       done.callBack((void*) this);
       break;

    case ICMPTypeDestinationUnreachable:
       residualHops = iip->timeToLive;
       responder.set(ip->source);
       switch (icmp->code) {
       case ICMPUnreachNet:
       case ICMPUnreachHost:
          result = ICMProbeResultUnreachable;
          break;
          
       case ICMPUnreachProto:
       case ICMPUnreachPort:
          result = ICMProbeResultReachedNode;
          break;
          
       case ICMPUnreachSrtFail:
          result = ICMProbeResultSourceRouteFailed;
          break;
          
       case ICMPUnreachNeedFrag:
       default:
          result = ICMProbeResultDontCare;
          break;
       }
       TRACE(traceICMProbe, "received icmprobe for %s:%d from %s\n",
             to.name(), hopcount, responder.name());
       done.callBack((void*) this);
       // FallThrough
       
    default:
       break;
    }
    return true;
}

//  Copyright (c) 1994 by the University of Southern California.
//  All rights reserved.
//
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//  and other materials related to such distribution and use acknowledge
//  that the software was developed by the University of Southern
//  California and/or Information Sciences Institute.
//  The name of the University of Southern California may not
//  be used to endorse or promote products derived from this software
//  without specific prior written permission.
//
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//  PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES,
//  INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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