source: libpacketdump/link_9.c @ ac7037b

/* Decoder for PPP with HDLC frames */

#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <inttypes.h>
#include <dlfcn.h>
#include "libtrace.h"
#include "libpacketdump.h"

typedef struct libtrace_hdlc_t {
        uint8_t address;        /** Always 0xff */
        uint8_t control;        /** Always 0x03 */
        uint16_t protocol;
} libtrace_hdlc_t;


DLLEXPORT void decode(int link_type UNUSED,const char *packet,unsigned len)
{
        libtrace_hdlc_t *frame = (libtrace_hdlc_t *)packet;

        printf(" PPP:");
        if (len >= 1)
                printf(" Address: 0x%02x", frame->address);
        else {
                printf("[|Truncated]\n");
                return;
        }
        
        if (len >= 2)
                printf(" Control: 0x%02x", frame->control);
        else {
                printf("[|Truncated]\n");
                return;
        }
        
        if (len >= 4) {
                printf(" Protocol: 0x%04x\n", ntohs(frame->protocol));
                
                /* PPP protocols do not match ethertypes, so we have to
                 * convert
                 *
                 * XXX develop decoders for PPP protocols so this can be
                 * done generically 
                 */
                if (ntohs(frame->protocol) == 0x0021) {
                        decode_next(packet + 4, len - 4, "eth", 0x0800);
                } 
        }
        else {
                printf("[|Truncated]\n");
                return;
        }
        

        return;
}