/*
 * Copyright (C) 1993-2001 by Darren Reed.
 *
 * See the IPFILTER.LICENCE file for details on licencing.
 *
 * $Id: ipft_pc.c,v 1.10 2004/02/07 18:17:40 darrenr Exp $
 */
#include "ipf.h"
#include "pcap-ipf.h"
#include "bpf-ipf.h"
#include "ipt.h"

#if !defined(lint)
static const char rcsid[] = "@(#)$Id: ipft_pc.c,v 1.10 2004/02/07 18:17:40 darrenr Exp $";
#endif

struct  llc     {
        int     lc_type;
        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.
 */

static  struct  llc     llcs[] = {
        { DLT_NULL, 0, 0, 0 },
        { DLT_EN10MB, 14, 12, 2 },
        { 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, 0, 0, 0 },
#ifdef DLT_ATMRFC1483
        { DLT_ATMRFC1483, 0, 0, 0 },
#endif
        { DLT_RAW, 0, 0, 0 },
#ifdef  DLT_ENC
        { DLT_ENC, 0, 0, 0 },
#endif
#ifdef  DLT_SLIP_BSDOS
        { DLT_SLIP_BSDOS, 0, 0, 0 },
#endif
#ifdef  DLT_PPP_BSDOS
        { DLT_PPP_BSDOS, 0, 0, 0 },
#endif
#ifdef  DLT_HIPPI
        { DLT_HIPPI, 0, 0, 0 },
#endif
#ifdef  DLT_HDLC
        { DLT_HDLC, 0, 0, 0 },
#endif
#ifdef  DLT_PPP_SERIAL
        { DLT_PPP_SERIAL, 4, 4, 0 },
#endif
#ifdef  DLT_PPP_ETHER
        { DLT_PPP_ETHER, 8, 8, 0 },
#endif
#ifdef  DLT_ECONET
        { DLT_ECONET, 0, 0, 0 },
#endif
        { -1, -1, -1, -1 }
};

static  int     pcap_open __P((char *));
static  int     pcap_close __P((void));
static  int     pcap_readip __P((char *, int, char **, int *));
static  void    swap_hdr __P((pcaphdr_t *));
static  int     pcap_read_rec __P((struct pcap_pkthdr *));

static  int     pfd = -1, swapped = 0;
static  struct llc      *llcp = NULL;

struct  ipread  pcap = { pcap_open, pcap_close, pcap_readip, 0 };

#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, i;

        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) {
                (void) close(fd);
                return -2;
        }

        for (i = 0; llcs[i].lc_type != -1; i++)
                if (llcs[i].lc_type == ph.pc_type) {
                        llcp = llcs + i;
                        break;
                }

        if (llcp == NULL) {
                (void) close(fd);
                return -2;
        }

        pfd = fd;
        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;

        l = llcp;

        /* 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;

                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;
}