/*
 * (C)opyright 1993-1996 by Darren Reed.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and due credit is given
 * to the original author and the contributors.
 */
#include <stdio.h>
#include <string.h>
#if !defined(__SVR4) && !defined(__GNUC__)
#include <strings.h>
#endif
#include <sys/types.h>
#include <sys/time.h>
#include <stdlib.h>
#include <unistd.h>
#include <stddef.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/param.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip_var.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>
#include <net/if.h>
#include "ip_fil.h"
#include "ipf.h"
#include "ipt.h"
#include "pcap.h"

#ifndef	lint
static	char	rcsid[] = "$Id: ipft_pc.c,v 1.4 1996/07/18 04:59:23 dm Exp $";
#endif

struct	llc	{
	int	lc_sz;	/* LLC header length */
	int	lc_to;	/* LLC Type offset */
	int	lc_tl;	/* LLC Type length */
};

/*
 * While many of these maybe the same, some do have different header formats
 * which make this useful.
 */
#define	DLT_MAX	10

static	struct	llc	llcs[DLT_MAX+1] = {
	{ 0, 0, 0 },	/* DLT_NULL */
	{ 14, 12, 2 },	/* DLT_E10MB */
	{ 0, 0, 0 },	/* DLT_EN3MB */
	{ 0, 0, 0 },	/* DLT_AX25 */
	{ 0, 0, 0 },	/* DLT_PRONET */
	{ 0, 0, 0 },	/* DLT_CHAOS */
	{ 0, 0, 0 },	/* DLT_IEEE802 */
	{ 0, 0, 0 },	/* DLT_ARCNET */
	{ 0, 0, 0 },	/* DLT_SLIP */
	{ 0, 0, 0 },	/* DLT_PPP */
	{ 0, 0, 0 }	/* DLT_FDDI */
};

static	int	pcap_open(), pcap_close(), pcap_readip();

static	int	pfd = -1, s_type = -1, swapped = 0;

struct	ipread	pcap = { pcap_open, pcap_close, pcap_readip };

#define	SWAPLONG(y)	\
	((((y)&0xff)<<24) | (((y)&0xff00)<<8) | (((y)&0xff0000)>>8) | (((y)>>24)&0xff))
#define	SWAPSHORT(y)	\
	( (((y)&0xff)<<8) | (((y)&0xff00)>>8) )

static	void	swap_hdr(p)
pcaphdr_t	*p;
{
	p->pc_v_maj = SWAPSHORT(p->pc_v_maj);
	p->pc_v_min = SWAPSHORT(p->pc_v_min);
	p->pc_zone = SWAPLONG(p->pc_zone);
	p->pc_sigfigs = SWAPLONG(p->pc_sigfigs);
	p->pc_slen = SWAPLONG(p->pc_slen);
	p->pc_type = SWAPLONG(p->pc_type);
}

static	int	pcap_open(fname)
char	*fname;
{
	pcaphdr_t ph;
	int	fd;

	if (pfd != -1)
		return pfd;

	if (!strcmp(fname, "-"))
		fd = 0;
	else if ((fd = open(fname, O_RDONLY)) == -1)
		return -1;

	if (read(fd, (char *)&ph, sizeof(ph)) != sizeof(ph))
		return -2;

	if (ph.pc_id != TCPDUMP_MAGIC) {
		if (SWAPLONG(ph.pc_id) != TCPDUMP_MAGIC) {
			(void) close(fd);
			return -2;
		}
		swapped = 1;
		swap_hdr(&ph);
	}

	if (ph.pc_v_maj != PCAP_VERSION_MAJ || ph.pc_type > DLT_MAX) {
		(void) close(fd);
		return -2;
	}

	pfd = fd;
	s_type = ph.pc_type;
	printf("opened pcap file %s:\n", fname);
	printf("\tid: %08x version: %d.%d type: %d snap %d\n",
		ph.pc_id, ph.pc_v_maj, ph.pc_v_min, ph.pc_type, ph.pc_slen);

	return fd;
}


static	int	pcap_close()
{
	return close(pfd);
}


/*
 * read in the header (and validate) which should be the first record
 * in a pcap file.
 */
static	int	pcap_read_rec(rec)
struct	pcap_pkthdr *rec;
{
	int	n, p;

	if (read(pfd, (char *)rec, sizeof(*rec)) != sizeof(*rec))
		return -2;

	if (swapped) {
		rec->ph_clen = SWAPLONG(rec->ph_clen);
		rec->ph_len = SWAPLONG(rec->ph_len);
		rec->ph_ts.tv_sec = SWAPLONG(rec->ph_ts.tv_sec);
		rec->ph_ts.tv_usec = SWAPLONG(rec->ph_ts.tv_usec);
	}
	p = rec->ph_clen;
	n = MIN(p, rec->ph_len);
	if (!n || n < 0)
		return -3;

	return p;
}


#ifdef	notyet
/*
 * read an entire pcap packet record.  only the data part is copied into
 * the available buffer, with the number of bytes copied returned.
 */
static	int	pcap_read(buf, cnt)
char	*buf;
int	cnt;
{
	struct	pcap_pkthdr rec;
	static	char	*bufp = NULL;
	int	i, n;

	if ((i = pcap_read_rec(&rec)) <= 0)
		return i;

	if (!bufp)
		bufp = malloc(i);
	else
		bufp = realloc(bufp, i);

	if (read(pfd, bufp, i) != i)
		return -2;

	n = MIN(i, cnt);
	bcopy(bufp, buf, n);
	return n;
}
#endif


/*
 * return only an IP packet read into buf
 */
static	int	pcap_readip(buf, cnt, ifn, dir)
char	*buf, **ifn;
int	cnt, *dir;
{
	static	char	*bufp = NULL;
	struct	pcap_pkthdr rec;
	struct	llc	*l;
	char	*s, ty[4];
	int	i, n;

	do {
		if ((i = pcap_read_rec(&rec)) <= 0)
			return i;

		if (!bufp)
			bufp = malloc(i);
		else
			bufp = realloc(bufp, i);
		s = bufp;

		if (read(pfd, s, i) != i)
			return -2;

		l = &llcs[s_type];
		i -= l->lc_sz;
		s += l->lc_to;
		bcopy(s, ty, l->lc_tl);
		s += l->lc_tl;
	} while (ty[0] != 0x8 && ty[1] != 0);
	n = MIN(i, cnt);
	bcopy(s, buf, n);
	return n;
}