inet::ICMP Class Reference

ICMP module. More...

#include <ICMP.h>

Inheritance diagram for inet::ICMP:

Public Member Functions
virtual void	sendErrorMessage (IPv4Datagram *datagram, int inputInterfaceId, ICMPType type, ICMPCode code)
	This method can be called from other modules to send an ICMP error packet in response to a received bogus packet. More...
virtual void	sendErrorMessage (cPacket *transportPacket, IPv4ControlInfo *ctrl, ICMPType type, ICMPCode code)
	This method can be called from other modules to send an ICMP error packet in response to a received bogus packet from the transport layer (like UDP). More...

Protected Types
typedef std::map< long, int >	PingMap

Protected Member Functions
virtual void	processICMPMessage (ICMPMessage *)
virtual void	errorOut (ICMPMessage *)
virtual void	processEchoRequest (ICMPMessage *)
virtual void	processEchoReply (ICMPMessage *)
virtual void	sendEchoRequest (PingPayload *)
virtual void	sendToIP (ICMPMessage *, const IPv4Address &dest)
virtual void	sendToIP (ICMPMessage *msg)
virtual bool	possiblyLocalBroadcast (const IPv4Address &addr, int interfaceId)
virtual int	numInitStages () const override
virtual void	initialize (int stage) override
virtual void	handleMessage (cMessage *msg) override

Protected Attributes
PingMap	pingMap

Detailed Description

ICMP module.

Member Typedef Documentation

typedef std::map<long, int> inet::ICMP::PingMap

protected

Member Function Documentation

void inet::ICMP::errorOut ( ICMPMessage *  icmpmsg )

protectedvirtual

Referenced by processICMPMessage().

{
    send(icmpmsg, "errorOut");
}

void inet::ICMP::handleMessage ( cMessage *  msg )

overrideprotectedvirtual

{
    cGate *arrivalGate = msg->getArrivalGate();

    // process arriving ICMP message
    if (!strcmp(arrivalGate->getName(), "localIn")) {
        EV_INFO << "Received " << msg << " from network protocol.\n";
        processICMPMessage(check_and_cast<ICMPMessage *>(msg));
        return;
    }

    // request from application
    if (!strcmp(arrivalGate->getName(), "pingIn")) {
        EV_INFO << "Received " << msg << " from upper layer.\n";
        sendEchoRequest(check_and_cast<PingPayload *>(msg));
        return;
    }
}

void inet::ICMP::initialize ( int  stage )

overrideprotectedvirtual

{
    cSimpleModule::initialize(stage);

    if (stage == INITSTAGE_NETWORK_LAYER_2) {
        IPSocket socket(gate("sendOut"));
        socket.registerProtocol(IP_PROT_ICMP);
    }
}

virtual int inet::ICMP::numInitStages ( ) const

inlineoverrideprotectedvirtual

{ return NUM_INIT_STAGES; }

bool inet::ICMP::possiblyLocalBroadcast ( const IPv4Address &  addr, int  interfaceId  )

protectedvirtual

Referenced by sendErrorMessage().

{
    if ((addr.getInt() & 1) == 0)
        return false;

    IIPv4RoutingTable *rt = getModuleFromPar<IIPv4RoutingTable>(par("routingTableModule"), this);
    if (rt->isLocalBroadcastAddress(addr))
        return true;

    // if the input interface is unconfigured, we won't recognize network-directed broadcasts because we don't what network we are on
    IInterfaceTable *ift = getModuleFromPar<IInterfaceTable>(par("interfaceTableModule"), this);
    if (interfaceId != -1) {
        InterfaceEntry *ie = ift->getInterfaceById(interfaceId);
        bool interfaceUnconfigured = (ie->ipv4Data() == nullptr) || ie->ipv4Data()->getIPAddress().isUnspecified();
        return interfaceUnconfigured;
    }
    else {
        // if all interfaces are configured, we are OK
        bool allInterfacesConfigured = true;
        for (int i = 0; i < (int)ift->getNumInterfaces(); i++)
            if ((ift->getInterface(i)->ipv4Data() == nullptr) || ift->getInterface(i)->ipv4Data()->getIPAddress().isUnspecified())
                allInterfacesConfigured = false;

        return !allInterfacesConfigured;
    }
}

void inet::ICMP::processEchoReply ( ICMPMessage *  reply )

protectedvirtual

Referenced by processICMPMessage().

{
    IPv4ControlInfo *ctrl = check_and_cast<IPv4ControlInfo *>(reply->removeControlInfo());
    PingPayload *payload = check_and_cast<PingPayload *>(reply->decapsulate());
    payload->setControlInfo(ctrl);
    delete reply;
    long originatorId = payload->getOriginatorId();
    auto i = pingMap.find(originatorId);
    if (i != pingMap.end()) {
        EV_INFO << "Sending " << payload << " to upper layer.\n";
        send(payload, "pingOut", i->second);
    }
    else {
        EV_WARN << "Received ECHO REPLY has an unknown originator ID: " << originatorId << ", packet dropped." << endl;
        delete payload;
    }
}

void inet::ICMP::processEchoRequest ( ICMPMessage *  request )

protectedvirtual

Referenced by processICMPMessage().

{
    // turn request into a reply
    ICMPMessage *reply = request;
    reply->setName((std::string(request->getName()) + "-reply").c_str());
    reply->setType(ICMP_ECHO_REPLY);

    // swap src and dest
    // TBD check what to do if dest was multicast etc?
    IPv4ControlInfo *ctrl = check_and_cast<IPv4ControlInfo *>(reply->getControlInfo());
    IPv4Address src = ctrl->getSrcAddr();
    IPv4Address dest = ctrl->getDestAddr();
    // A. Ariza Modification 5/1/2011 clean the interface id, this forces the use of routing table in the IPv4 layer
    ctrl->setInterfaceId(-1);
    ctrl->setSrcAddr(dest);
    ctrl->setDestAddr(src);
    ctrl->setTimeToLive(0); // if the TTL is set to 0 here, IP resets it to the default TTL

    sendToIP(reply);
}

void inet::ICMP::processICMPMessage ( ICMPMessage *  icmpmsg )

protectedvirtual

Referenced by handleMessage(), and sendErrorMessage().

{
    switch (icmpmsg->getType()) {
        case ICMP_DESTINATION_UNREACHABLE:
            errorOut(icmpmsg);
            break;

        case ICMP_REDIRECT:
            errorOut(icmpmsg);
            break;

        case ICMP_TIME_EXCEEDED:
            errorOut(icmpmsg);
            break;

        case ICMP_PARAMETER_PROBLEM:
            errorOut(icmpmsg);
            break;

        case ICMP_ECHO_REQUEST:
            processEchoRequest(icmpmsg);
            break;

        case ICMP_ECHO_REPLY:
            processEchoReply(icmpmsg);
            break;

        case ICMP_TIMESTAMP_REQUEST:
            processEchoRequest(icmpmsg);
            break;

        case ICMP_TIMESTAMP_REPLY:
            processEchoReply(icmpmsg);
            break;

        default:
            throw cRuntimeError("Unknown ICMP type %d", icmpmsg->getType());
    }
}

void inet::ICMP::sendEchoRequest ( PingPayload *  msg )

protectedvirtual

Referenced by handleMessage().

{
    cGate *arrivalGate = msg->getArrivalGate();
    int i = arrivalGate->getIndex();
    pingMap[msg->getOriginatorId()] = i;

    IPv4ControlInfo *ctrl = check_and_cast<IPv4ControlInfo *>(msg->removeControlInfo());
    ctrl->setProtocol(IP_PROT_ICMP);
    ICMPMessage *request = new ICMPMessage(msg->getName());
    request->setByteLength(4);
    request->setType(ICMP_ECHO_REQUEST);
    request->encapsulate(msg);
    request->setControlInfo(ctrl);
    sendToIP(request);
}

void inet::ICMP::sendErrorMessage ( IPv4Datagram *  datagram, int  inputInterfaceId, ICMPType  type, ICMPCode  code  )

virtual

This method can be called from other modules to send an ICMP error packet in response to a received bogus packet.

It will not send ICMP error in response to broadcast or multicast packets – in that case it will simply delete the packet. Kludge: if inputInterfaceId cannot be determined, pass in -1.

Referenced by inet::IPv4FragBuf::purgeStaleFragments(), and sendErrorMessage().

{
    Enter_Method("sendErrorMessage(datagram, type=%d, code=%d)", type, code);

    // get ownership
    take(origDatagram);

    IPv4Address origSrcAddr = origDatagram->getSrcAddress();
    IPv4Address origDestAddr = origDatagram->getDestAddress();

    // don't send ICMP error messages in response to broadcast or multicast messages
    if (origDestAddr.isMulticast() || origDestAddr.isLimitedBroadcastAddress() || possiblyLocalBroadcast(origDestAddr, inputInterfaceId)) {
        EV_DETAIL << "won't send ICMP error messages for broadcast/multicast message " << origDatagram << endl;
        delete origDatagram;
        return;
    }

    // don't send ICMP error messages response to unspecified, broadcast or multicast addresses
    if ((inputInterfaceId != -1 && origSrcAddr.isUnspecified())
            || origSrcAddr.isMulticast()
            || origSrcAddr.isLimitedBroadcastAddress()
            || possiblyLocalBroadcast(origSrcAddr, inputInterfaceId)) {
        EV_DETAIL << "won't send ICMP error messages to broadcast/multicast address, message " << origDatagram << endl;
        delete origDatagram;
        return;
    }

    // do not reply with error message to error message
    if (origDatagram->getTransportProtocol() == IP_PROT_ICMP) {
        ICMPMessage *recICMPMsg = check_and_cast<ICMPMessage *>(origDatagram->getEncapsulatedPacket());
        if (!isIcmpInfoType(recICMPMsg->getType())) {
            EV_DETAIL << "ICMP error received -- do not reply to it" << endl;
            delete origDatagram;
            return;
        }
    }

    // assemble a message name
    char msgname[80];
    static long ctr;
    sprintf(msgname, "ICMP-error-#%ld-type%d-code%d", ++ctr, type, code);

    // debugging information
    EV_DETAIL << "sending ICMP error " << msgname << endl;

    // create and send ICMP packet
    ICMPMessage *errorMessage = new ICMPMessage(msgname);
    errorMessage->setType(type);
    errorMessage->setCode(code);
    errorMessage->encapsulate(origDatagram);

    // ICMP message length: the internet header plus the first 8 bytes of
    // the original datagram's data is returned to the sender.
    //
    // NOTE: since we just overwrite the errorMessage length without actually
    // truncating origDatagram, one can get "packet length became negative"
    // error when decapsulating the origDatagram on the receiver side.
    // A workaround is to avoid decapsulation, or to manually set the
    // errorMessage length to be larger than the encapsulated message.
    int dataLength = origDatagram->getByteLength() - origDatagram->getHeaderLength();
    int truncatedDataLength = dataLength <= 8 ? dataLength : 8;
    errorMessage->setByteLength(8 + origDatagram->getHeaderLength() + truncatedDataLength);

    // if srcAddr is not filled in, we're still in the src node, so we just
    // process the ICMP message locally, right away
    if (origSrcAddr.isUnspecified()) {
        // pretend it came from the IPv4 layer
        IPv4ControlInfo *controlInfo = new IPv4ControlInfo();
        controlInfo->setSrcAddr(IPv4Address::LOOPBACK_ADDRESS);    // FIXME maybe use configured loopback address
        controlInfo->setProtocol(IP_PROT_ICMP);
        errorMessage->setControlInfo(controlInfo);

        // then process it locally
        processICMPMessage(errorMessage);
    }
    else {
        sendToIP(errorMessage, origDatagram->getSrcAddress());
    }
}

void inet::ICMP::sendErrorMessage ( cPacket *  transportPacket, IPv4ControlInfo *  ctrl, ICMPType  type, ICMPCode  code  )

virtual

This method can be called from other modules to send an ICMP error packet in response to a received bogus packet from the transport layer (like UDP).

It will not send ICMP error in response to broadcast or multicast packets – in that case it will simply delete the packet. The ICMP error packet needs to include (part of) the original IPv4 datagram, so this function will wrap back the transport packet into the IPv4 datagram based on its IPv4ControlInfo.

{
    Enter_Method("sendErrorMessage(transportPacket, ctrl, type=%d, code=%d)", type, code);

    IPv4Datagram *datagram = ctrl->removeOrigDatagram();
    int inputInterfaceId = ctrl->getInterfaceId();
    delete ctrl;
    take(transportPacket);
    take(datagram);
    datagram->encapsulate(transportPacket);
    sendErrorMessage(datagram, inputInterfaceId, type, code);
}

void inet::ICMP::sendToIP ( ICMPMessage *  msg, const IPv4Address &  dest  )

protectedvirtual

Referenced by processEchoRequest(), sendEchoRequest(), and sendErrorMessage().

{
    IPv4ControlInfo *controlInfo = new IPv4ControlInfo();
    controlInfo->setDestAddr(dest);
    controlInfo->setProtocol(IP_PROT_ICMP);
    msg->setControlInfo(controlInfo);
    sendToIP(msg);
}

void inet::ICMP::sendToIP ( ICMPMessage *  msg )

protectedvirtual

{
    // assumes IPv4ControlInfo is already attached
    EV_INFO << "Sending " << msg << " to lower layer.\n";
    send(msg, "sendOut");
}

Member Data Documentation

PingMap inet::ICMP::pingMap

protected

Referenced by processEchoReply(), and sendEchoRequest().

---

The documentation for this class was generated from the following files:

• ICMP.h
• ICMP.cc