/*
 *	       Input/Output VJ Compressed packets
 *
 *	    Written by Toshiharu OHNO (tony-o@iij.ad.jp)
 *
 *   Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the Internet Initiative Japan, Inc.  The name of the
 * IIJ may not 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 MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * $Id: vjcomp.c,v 1.3 1995/05/30 03:51:02 rgrimes Exp $
 *
 *  TODO:
 */
#include "fsm.h"
#include "lcpproto.h"
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include "slcompress.h"
#include "hdlc.h"
#include "ipcp.h"

#define MAX_VJHEADER 16	/* Maximum size of compressed header */

struct slcompress cslc;

void
VjInit()
{
  sl_compress_init(&cslc);
}

void
SendPppFrame(bp)
struct mbuf *bp;
{
  int type;
  int proto;
  int cproto = IpcpInfo.his_compproto >> 16;

#ifdef DEBUG
  logprintf("SendPppFrame: proto = %x\n", IpcpInfo.his_compproto);
#endif
  if (cproto== PROTO_VJCOMP) {
    type = sl_compress_tcp(bp, (struct ip *)MBUF_CTOP(bp), &cslc, IpcpInfo.his_compproto & 0xff);

#ifdef DEBUG
    logprintf("type = %x\n", type);
#endif
    switch (type) {
    case TYPE_IP:
      proto = PROTO_IP;
      break;
    case TYPE_UNCOMPRESSED_TCP:
      proto = PROTO_VJUNCOMP;
      break;
    case TYPE_COMPRESSED_TCP:
      proto = PROTO_VJCOMP;
      break;
    default:
      logprintf("unknown type %x\n", type);
      pfree(bp);
      return;
    }
  } else
    proto = PROTO_IP;
  HdlcOutput(PRI_NORMAL, proto, bp);
}

static struct mbuf *
VjUncompressTcp(bp, type)
struct mbuf *bp;
u_char type;
{
  u_char *bufp;
  int len, olen, rlen;
  struct mbuf *nbp;
  u_char work[MAX_HDR+MAX_VJHEADER];   /* enough to hold TCP/IP header */

  olen = len = plength(bp);
  if (type == TYPE_UNCOMPRESSED_TCP) {
    /*
     * Uncompressed packet does NOT change its size, so that we can
     * use mbuf space for uncompression job.
     */
    bufp = MBUF_CTOP(bp);
    len = sl_uncompress_tcp(&bufp, len, type, &cslc);
    if (len <= 0) {
      pfree(bp);
      bp = NULLBUFF;
    }
    return(bp);
  }
  /*
   *  Handle compressed packet.
   *    1) Read upto MAX_VJHEADER bytes into work space.
   *	2) Try to uncompress it.
   *    3) Compute amount of necesary space.
   *    4) Copy unread data info there.
   */
  if (len > MAX_VJHEADER) len = MAX_VJHEADER;
  rlen = len;
  bufp = work + MAX_HDR;
  bp = mbread(bp, bufp, rlen);
  len = sl_uncompress_tcp(&bufp, olen, type, &cslc);
  if (len <= 0) {
    pfree(bp);
    return NULLBUFF;
  }
  len -= olen;
  len += rlen;
  nbp = mballoc(len, MB_VJCOMP);
  bcopy(bufp, MBUF_CTOP(nbp), len);
  nbp->next = bp;
  return(nbp);
}

struct mbuf *
VjCompInput(bp, proto)
struct mbuf *bp;
int proto;
{
  u_char type;

#ifdef DEBUG
  logprintf("VjCompInput (%02x):\n", proto);
  DumpBp(bp);
#endif

  switch (proto) {
  case PROTO_VJCOMP:
    type = TYPE_COMPRESSED_TCP;
    break;
  case PROTO_VJUNCOMP:
    type = TYPE_UNCOMPRESSED_TCP;
    break;
  default:
    logprintf("???\n");
    return(bp);
  }
  bp = VjUncompressTcp(bp, type);
  return(bp);
}
