/*
* Copyright (c) 1989, 1990, 1991, 1993, 1994, 1995, 1996, 1997
*      The Regents of the University of California.  All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
* the University nor the names of its contributors may be used to endorse
* or promote products derived from this software without specific prior
* written permission.
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*/

#include <sys/cdefs.h>
#ifndef lint
__RCSID("$NetBSD: print-sl.c,v 1.11 2024/09/02 16:15:33 christos Exp $");
#endif

/* \summary: Compressed Serial Line Internet Protocol printer */

#include <config.h>

#include "netdissect-stdinc.h"

#define ND_LONGJMP_FROM_TCHECK
#include "netdissect.h"
#include "extract.h"

#include "ip.h"
#include "tcp.h"
#include "slcompress.h"

/*
* definitions of the pseudo- link-level header attached to slip
* packets grabbed by the packet filter (bpf) traffic monitor.
*/
#define SLIP_HDRLEN 16

#define SLX_DIR 0
#define SLX_CHDR 1

#define SLIPDIR_IN 0
#define SLIPDIR_OUT 1


static u_int lastlen[2][256];
static u_int lastconn = 255;

static void sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
static void compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);

void
sl_if_print(netdissect_options *ndo,
           const struct pcap_pkthdr *h, const u_char *p)
{
       u_int length = h->len;
       const struct ip *ip;

       ndo->ndo_protocol = "slip";
       ND_TCHECK_LEN(p, SLIP_HDRLEN);
       ndo->ndo_ll_hdr_len += SLIP_HDRLEN;

       length -= SLIP_HDRLEN;

       ip = (const struct ip *)(p + SLIP_HDRLEN);

       if (ndo->ndo_eflag)
               sliplink_print(ndo, p, ip, length);

       switch (IP_V(ip)) {
       case 4:
               ip_print(ndo, (const u_char *)ip, length);
               break;
       case 6:
               ip6_print(ndo, (const u_char *)ip, length);
               break;
       default:
               ND_PRINT("ip v%u", IP_V(ip));
       }
}

void
sl_bsdos_if_print(netdissect_options *ndo,
                 const struct pcap_pkthdr *h, const u_char *p)
{
       u_int length = h->len;
       const struct ip *ip;

       ndo->ndo_protocol = "slip_bsdos";
       ND_TCHECK_LEN(p, SLIP_HDRLEN);
       ndo->ndo_ll_hdr_len += SLIP_HDRLEN;

       length -= SLIP_HDRLEN;

       ip = (const struct ip *)(p + SLIP_HDRLEN);

#ifdef notdef
       if (ndo->ndo_eflag)
               sliplink_print(ndo, p, ip, length);
#endif

       ip_print(ndo, (const u_char *)ip, length);
}

static void
sliplink_print(netdissect_options *ndo,
              const u_char *p, const struct ip *ip,
              u_int length)
{
       int dir;
       u_int hlen;

       dir = GET_U_1(p + SLX_DIR);
       switch (dir) {

       case SLIPDIR_IN:
               ND_PRINT("I ");
               break;

       case SLIPDIR_OUT:
               ND_PRINT("O ");
               break;

       default:
               ND_PRINT("Invalid direction %d ", dir);
               dir = -1;
               break;
       }
       switch (GET_U_1(p + SLX_CHDR) & 0xf0) {

       case TYPE_IP:
               ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
               break;

       case TYPE_UNCOMPRESSED_TCP:
               /*
                * The connection id is stored in the IP protocol field.
                * Get it from the link layer since sl_uncompress_tcp()
                * has restored the IP header copy to IPPROTO_TCP.
                */
               lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
               ND_PRINT("utcp %u: ", lastconn);
               if (dir == -1) {
                       /* Direction is bogus, don't use it */
                       return;
               }
               ND_TCHECK_SIZE(ip);
               hlen = IP_HL(ip);
               ND_TCHECK_SIZE((const struct tcphdr *)&((const int *)ip)[hlen]);
               hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
               lastlen[dir][lastconn] = length - (hlen << 2);
               break;

       default:
               if (dir == -1) {
                       /* Direction is bogus, don't use it */
                       return;
               }
               if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
                       compressed_sl_print(ndo, p + SLX_CHDR, ip, length, dir);
                       ND_PRINT(": ");
               } else
                       ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
       }
}

static const u_char *
print_sl_change(netdissect_options *ndo,
               const char *str, const u_char *cp)
{
       u_int i;

       if ((i = GET_U_1(cp)) == 0) {
               cp++;
               i = GET_BE_U_2(cp);
               cp += 2;
       }
       ND_PRINT(" %s%u", str, i);
       return (cp);
}

static const u_char *
print_sl_winchange(netdissect_options *ndo,
                  const u_char *cp)
{
       int16_t i;

       if ((i = GET_U_1(cp)) == 0) {
               cp++;
               i = GET_BE_S_2(cp);
               cp += 2;
       }
       if (i >= 0)
               ND_PRINT(" W+%d", i);
       else
               ND_PRINT(" W%d", i);
       return (cp);
}

static void
compressed_sl_print(netdissect_options *ndo,
                   const u_char *chdr, const struct ip *ip,
                   u_int length, int dir)
{
       const u_char *cp = chdr;
       u_int flags, hlen;

       flags = GET_U_1(cp);
       cp++;
       if (flags & NEW_C) {
               lastconn = GET_U_1(cp);
               cp++;
               ND_PRINT("ctcp %u", lastconn);
       } else
               ND_PRINT("ctcp *");

       /* skip tcp checksum */
       cp += 2;

       switch (flags & SPECIALS_MASK) {
       case SPECIAL_I:
               ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
               break;

       case SPECIAL_D:
               ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
               break;

       default:
               if (flags & NEW_U)
                       cp = print_sl_change(ndo, "U=", cp);
               if (flags & NEW_W)
                       cp = print_sl_winchange(ndo, cp);
               if (flags & NEW_A)
                       cp = print_sl_change(ndo, "A+", cp);
               if (flags & NEW_S)
                       cp = print_sl_change(ndo, "S+", cp);
               break;
       }
       if (flags & NEW_I)
               cp = print_sl_change(ndo, "I+", cp);

       /*
        * 'hlen' is the length of the uncompressed TCP/IP header (in words).
        * 'cp - chdr' is the length of the compressed header.
        * 'length - hlen' is the amount of data in the packet.
        */
       ND_TCHECK_SIZE(ip);
       hlen = IP_HL(ip);
       ND_TCHECK_SIZE((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
       hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
       lastlen[dir][lastconn] = length - (hlen << 2);
       ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
}

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