/*
 *	Copyright (c) 1993-1997 JSC Rinet, Novosibirsk, Russia
 *
 * Redistribution and use in source forms, with and without modification,
 * are permitted provided that this entire comment appears intact.
 * Redistribution in binary form may occur without any restrictions.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' WITHOUT ANY WARRANTIES OF ANY KIND.
 */

/* interfaces.h -- network interface data-link level routines */

#ifdef	HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/param.h>
#include <sys/types.h>
#ifdef	HAVE_SYS_MBUF_H
#include <sys/mbuf.h>
#endif
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#ifdef	HAVE_NET_SLIP_H
#include <net/slip.h>
#include <net/slcompress.h>
#endif

#include <pcap.h>
#include "trafshow.h"

u_char *snapend;

/* Link-level header length */
#ifndef	ETHER_HDRLEN
#define	ETHER_HDRLEN	sizeof(struct ether_header)
#endif

#ifndef	SLIP_HDRLEN
#ifdef	SLC_BPFHDR
#define	SLIP_HDRLEN	SLC_BPFHDR	/* if _BSDI_VERSION >= 199510 */
#else
#define	SLIP_HDRLEN	16	/* bpf slip header length */
#endif
#endif

#ifndef	PPP_HDRLEN
#ifdef	SLC_BPFHDR
#define	PPP_HDRLEN	SLC_BPFHDR	/* if _BSDI_VERSION >= 199510 */
#else
#define	PPP_HDRLEN	4	/* sizeof(struct ppp_header) */
#endif
#endif

#ifdef	DLT_C_HDLC
#ifndef	CHDLC_HDRLEN
#define	CHDLC_HDRLEN	4	/* sizeof(struct cisco_hdr) */
#endif
#endif

#ifndef	NULL_HDRLEN
#define	NULL_HDRLEN	4	/* loopback header length */
#endif

/*
 * This is the interface depended routines for ethernet, slip, ppp and lo.
 *	'p' is the points to the packet,
 *	'length' is the length of the packet,
 *	'caplen' is the number of bytes actually captured.
 */
void
if_ether(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;

	if (caplen < ETHER_HDRLEN) return;

	snapend = p + caplen;
	if (eflag ||
	    ntohs(((struct ether_header *)p)->ether_type) == ETHERTYPE_IP)
		display(p, p + ETHER_HDRLEN, length - ETHER_HDRLEN);
}

void
if_slip(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;

	if (caplen < SLIP_HDRLEN) return;

	snapend = p + caplen;
	display(NULL, p + SLIP_HDRLEN, length - SLIP_HDRLEN);
}

void
if_ppp(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;
	register hdrlen = 0;
	u_short type;
	u_char *packetp;

	if (caplen < PPP_HDRLEN) return;

	packetp = p;
	snapend = p + caplen;

#ifdef	SLC_BPFHDRLEN
	p += SLC_BPFHDRLEN;	/* pointer to link level header */
#endif
	/* PPP address and PPP control fields may be present (-acfc) */
	if (p[0] == 0xff && p[1] == 0x03) {
		p += 2;
		hdrlen += 2;
	}
	/* Retrive the protocol type */
	if (*p & 01) {	/* Compressed protocol field (pfc) */
		type = *p++;
		hdrlen++;
	} else {	/* Un-compressed protocol field (-pfc) */
		type = ntohs(*(u_short *)p);
		p += 2;
		hdrlen += 2;
	}
	if (type == 0x21) {	/* IP protocol */
#ifdef	SLC_BPFHDR
		p = packetp + SLC_BPFHDR;	/* skip bpf pseudo header */
		hdrlen = SLC_BPFHDR;
#endif
		display(NULL, p, length - hdrlen);
	}
}

#ifdef	DLT_C_HDLC
void
if_chdlc(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;

	if (caplen < CHDLC_HDRLEN) return;

	snapend = p + caplen;
	if (ntohs(*(u_short *)(p + 2)) == 0x0800) /* IP protocol */
		display(NULL, p + CHDLC_HDRLEN, length - CHDLC_HDRLEN);
}
#endif

#ifdef	DLT_RAW
void
if_rawip(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;

	snapend = p + caplen;
	display(NULL, p, length);
}
#endif

void
if_null(user, h, p)
	char *user;
	struct pcap_pkthdr *h;
	register u_char *p;
{
	u_int caplen = h->caplen;
	u_int length = h->len;
  	u_int family;

	memcpy(&family, p, sizeof(family));
	snapend = p + caplen;
	if (family == AF_INET)
		display(NULL, p + NULL_HDRLEN, length - NULL_HDRLEN);
}

/*
 * hardware depended funtions table.
 */
static struct if_func {
	void (*f)();
	int type;
} if_funcs[] = {
	{	if_ether,	DLT_EN10MB	},	/* Ethernet */
#ifdef	DLT_IEEE802
	{	if_ether,	DLT_IEEE802	},	/* IEEE 802 */
#endif
	{	if_slip,	DLT_SLIP	},	/* SLIP */
#ifdef	DLT_SLIP_BSDOS
	{	if_slip,	DLT_SLIP_BSDOS	}, /* libpcap stupid fake */
#endif
	{	if_ppp,		DLT_PPP		},	/* PPP */
#ifdef	DLT_PPP_BSDOS
	{	if_ppp,		DLT_PPP_BSDOS	}, /* libpcap stupid fake */
#endif
#ifdef	DLT_C_HDLC
	{	if_chdlc,	DLT_C_HDLC	},	/* Cisco HDLC */
#endif
#ifdef	DLT_RAW
	{	if_rawip,	DLT_RAW		},	/* raw IP */
#endif
	{	if_null,	DLT_NULL	},	/* loopback */
	{ NULL, 0 },
};

/*
 * Assign data link type to interface function.
 */
pcap_handler
lookup_if(type)
	int type;
{
	struct if_func *p;

	for (p = if_funcs; p->f != NULL; ++p)
		if (type == p->type) return p->f;
	error(0, "unknown data link type 0x%x", type);

	/* NOTREACHED */
	return 0;
}