source: examples/tracedump/ip_17.cc @ 5d6ebe1

#include <stdio.h>
#include <stdint.h>
#include <dlfcn.h>
#include <map>
#include "tracedump.h"
#include <netinet/udp.h>
#include <netinet/in.h>

#define STRUCT udp

#define SAFE(x) \
        ((unsigned int)len>=((char*)&STRUCT->x-(char*)STRUCT+sizeof(STRUCT->x))) 
#define DISPLAY_EXP(x,fmt,exp) \
        if (SAFE(x)) \
                printf(fmt,exp); \
        else \
                return; 

#define DISPLAY(x,fmt) DISPLAY_EXP(x,fmt,STRUCT->x)

#define DISPLAYS(x,fmt) DISPLAY_EXP(x,fmt,htons(STRUCT->x))
#define DISPLAYL(x,fmt) DISPLAY_EXP(x,fmt,htonl(STRUCT->x))
#define DISPLAYIP(x,fmt) DISPLAY_EXP(x,fmt,inet_ntoa(*(struct in_addr*)&STRUCT->x))


extern "C"
void decode(int link_type,char *packet,int len)
{
        struct udphdr *udp = (struct udphdr*)packet;
        printf(" UDP:");
        DISPLAYS(source," Source %i")
        DISPLAYS(dest," Dest %i")
        printf("\n UDP:");
        DISPLAYS(len," Len %u");
        DISPLAYS(check," Checksum %u");
        printf("\n");
        if (htons(udp->source) < htons(udp->dest)) 
                decode_next(packet+sizeof(*udp),len-sizeof(*udp),"udp",htons(udp->source));
        else
                decode_next(packet+sizeof(*udp),len-sizeof(*udp),"udp",htons(udp->dest));
        return;
}