IPSerializer Class Reference

#include <IPSerializer.h>

List of all members.

Public Member Functions
	IPSerializer ()
int	serialize (const IPDatagram *dgram, unsigned char *buf, unsigned int bufsize)
void	parse (const unsigned char *buf, unsigned int bufsize, IPDatagram *dest)

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Detailed Description

Converts between IPDatagram and binary (network byte order) IP header.

Definition at line 27 of file IPSerializer.h.

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Constructor & Destructor Documentation

IPSerializer::IPSerializer

(

)

[inline]

Definition at line 30 of file IPSerializer.h.

{}

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Member Function Documentation

void IPSerializer::parse	(	const unsigned char *	buf,
		unsigned int	bufsize,
		IPDatagram *	dest
	)

Puts a packet sniffed from the wire into an IPDatagram. Does NOT verify the checksum.

Definition at line 107 of file IPSerializer.cc.

{
    const struct ip *ip = (const struct ip *) buf;
    unsigned int totalLength, headerLength;

    dest->setVersion(ip->ip_v);
    dest->setHeaderLength(IP_HEADER_BYTES);
    dest->setSrcAddress(ntohl(ip->ip_src.s_addr));
    dest->setDestAddress(ntohl(ip->ip_dst.s_addr));
    dest->setTransportProtocol(ip->ip_p);
    dest->setTimeToLive(ip->ip_ttl);
    dest->setIdentification(ntohs(ip->ip_id));
    dest->setMoreFragments((ip->ip_off) & !IP_OFFMASK & IP_MF);
    dest->setDontFragment((ip->ip_off) & !IP_OFFMASK & IP_DF);
    dest->setFragmentOffset((ntohs(ip->ip_off)) & IP_OFFMASK);
    dest->setDiffServCodePoint(ip->ip_tos);
    totalLength = ntohs(ip->ip_len);
    headerLength = ip->ip_hl << 2;

    if (headerLength > (unsigned int)IP_HEADER_BYTES)
        EV << "Handling an captured IP packet with options. Dropping the options.\n";
    if (totalLength > bufsize)
        EV << "Can not handle IP packet of total length " << totalLength << "(captured only " << bufsize << " bytes).\n";
    dest->setByteLength(IP_HEADER_BYTES);

    cPacket *encapPacket = NULL;
    switch (dest->getTransportProtocol())
    {
      case IP_PROT_ICMP:
        encapPacket = new ICMPMessage("icmp-from-wire");
        ICMPSerializer().parse(buf + headerLength, std::min(totalLength, bufsize) - headerLength, (ICMPMessage *)encapPacket);
        break;
      case IP_PROT_UDP:
        encapPacket = new UDPPacket("udp-from-wire");
        UDPSerializer().parse(buf + headerLength, std::min(totalLength, bufsize) - headerLength, (UDPPacket *)encapPacket);
        break;
      case IP_PROT_SCTP:
        encapPacket = new SCTPMessage("sctp-from-wire");
        SCTPSerializer().parse(buf + headerLength, (unsigned int)(std::min(totalLength, bufsize) - headerLength), (SCTPMessage *)encapPacket);
        break;
      case IP_PROT_TCP:
        encapPacket = new TCPSegment("tcp-from-wire");
        TCPSerializer().parse(buf + headerLength, (unsigned int)(std::min(totalLength, bufsize) - headerLength), (TCPSegment *)encapPacket);
        break;
      default:
        opp_error("IPSerializer: cannot serialize protocol %d", dest->getTransportProtocol());
    }

    ASSERT(encapPacket);
    dest->encapsulate(encapPacket);
    dest->setName(encapPacket->getName());
}

int IPSerializer::serialize	(	const IPDatagram *	dgram,
		unsigned char *	buf,
		unsigned int	bufsize
	)

Serializes an IPDatagram for transmission on the wire. The checksum is NOT filled in. (The kernel does that when sending the frame over a raw socket.) Returns the length of data written into buffer.

Definition at line 57 of file IPSerializer.cc.

{
    int packetLength;
    struct ip *ip = (struct ip *) buf;

    ip->ip_hl         = IP_HEADER_BYTES >> 2;
    ip->ip_v          = dgram->getVersion();
    ip->ip_tos        = dgram->getDiffServCodePoint();
    ip->ip_id         = htons(dgram->getIdentification());
    ip->ip_off        = htons(dgram->getFragmentOffset());
    ip->ip_ttl        = dgram->getTimeToLive();
    ip->ip_p          = dgram->getTransportProtocol();
    ip->ip_src.s_addr = htonl(dgram->getSrcAddress().getInt());
    ip->ip_dst.s_addr = htonl(dgram->getDestAddress().getInt());
    ip->ip_sum        = 0;

    if (dgram->getHeaderLength() > IP_HEADER_BYTES)
        EV << "Serializing an IP packet with options. Dropping the options.\n";

    packetLength = IP_HEADER_BYTES;

    cMessage *encapPacket = dgram->getEncapsulatedMsg();
    switch (dgram->getTransportProtocol())
    {
      case IP_PROT_ICMP:
        packetLength += ICMPSerializer().serialize(check_and_cast<ICMPMessage *>(encapPacket),
                                                   buf+IP_HEADER_BYTES, bufsize-IP_HEADER_BYTES);
        break;
      case IP_PROT_UDP:
        packetLength += UDPSerializer().serialize(check_and_cast<UDPPacket *>(encapPacket),
                                                   buf+IP_HEADER_BYTES, bufsize-IP_HEADER_BYTES);
        break;
      case IP_PROT_SCTP:    //I.R.
        packetLength += SCTPSerializer().serialize(check_and_cast<SCTPMessage *>(encapPacket),
                                                   buf+IP_HEADER_BYTES, bufsize-IP_HEADER_BYTES);
        break;
      case IP_PROT_TCP:        //I.R.
        packetLength += TCPSerializer().serialize(check_and_cast<TCPSegment *>(encapPacket),
                                                   buf+IP_HEADER_BYTES, bufsize-IP_HEADER_BYTES,
                                                   dgram->getSrcAddress(), dgram->getDestAddress());
        break;
      default:
        opp_error("IPSerializer: cannot serialize protocol %d", dgram->getTransportProtocol());
    }

    ip->ip_len = htons(packetLength);

    return packetLength;
}

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

• IPSerializer.h
• IPSerializer.cc