ipelement.hh

/*
 * ipelement.hh - Provides several methods that can be used by elements to manage IP packets
 *
 * Romain Gaillard.
 */
 
#ifndef MIDDLEBOX_IPELEMENT_HH
#define MIDDLEBOX_IPELEMENT_HH
 
#include <click/config.h>
#include <click/glue.hh>
#include <click/element.hh>
 
CLICK_DECLS
 
class IPElement
{
public:
    inline uint16_t packetTotalLength(Packet* packet) const;
 
    inline uint16_t getIPHeaderOffset(Packet* packet) const;
 
    inline void setPacketTotalLength(WritablePacket* packet, unsigned length) const;
 
    inline const uint32_t getDestinationAddress(Packet* packet) const;
 
    inline const uint32_t getSourceAddress(Packet* packet) const;
 
    inline void computeIPChecksum(WritablePacket* packet) const;
};
 
inline uint16_t IPElement::packetTotalLength(Packet *packet) const
{
    const click_ip *iph = packet->ip_header();
 
    return ntohs(iph->ip_len);
}
 
inline uint16_t IPElement::getIPHeaderOffset(Packet *packet) const
{
    return (((const unsigned char *)packet->ip_header()) - packet->data());
}
 
inline void IPElement::setPacketTotalLength(WritablePacket* packet, unsigned length) const
{
    click_ip *iph = packet->ip_header();
    iph->ip_len = htons(length);
}
 
 
inline void IPElement::computeIPChecksum(WritablePacket *packet) const
{
    click_ip *iph = packet->ip_header();
 
    //unsigned plen = ntohs(iph->ip_len) - (iph->ip_hl << 2);
    unsigned hlen = iph->ip_hl << 2;
 
    iph->ip_sum = 0;
    iph->ip_sum = click_in_cksum((const unsigned char *)iph, hlen);
}
 
inline const uint32_t IPElement::getSourceAddress(Packet* packet) const
{
    const click_ip *iph = packet->ip_header();
 
    return *(const uint32_t*)&iph->ip_src;
}
 
inline const uint32_t IPElement::getDestinationAddress(Packet* packet) const
{
    const click_ip *iph = packet->ip_header();
 
    return *(const uint32_t*)&iph->ip_dst;
}
 
CLICK_ENDDECLS
#endif