vjcomp.c revision 13733 
1/*
2 *	       Input/Output VJ Compressed packets
3 *
4 *	    Written by Toshiharu OHNO (tony-o@iij.ad.jp)
5 *
6 *   Copyright (C) 1993, Internet Initiative Japan, Inc. All rights reserverd.
7 *
8 * Redistribution and use in source and binary forms are permitted
9 * provided that the above copyright notice and this paragraph are
10 * duplicated in all such forms and that any documentation,
11 * advertising materials, and other materials related to such
12 * distribution and use acknowledge that the software was developed
13 * by the Internet Initiative Japan, Inc.  The name of the
14 * IIJ may not be used to endorse or promote products derived
15 * from this software without specific prior written permission.
16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
18 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
19 *
20 * $Id: vjcomp.c,v 1.3 1995/05/30 03:51:02 rgrimes Exp $
21 *
22 *  TODO:
23 */
24#include "fsm.h"
25#include "lcpproto.h"
26#include <netinet/in_systm.h>
27#include <netinet/ip.h>
28#include "slcompress.h"
29#include "hdlc.h"
30#include "ipcp.h"
31
32#define MAX_VJHEADER 16	/* Maximum size of compressed header */
33
34struct slcompress cslc;
35
36void
37VjInit()
38{
39  sl_compress_init(&cslc);
40}
41
42void
43SendPppFrame(bp)
44struct mbuf *bp;
45{
46  int type;
47  int proto;
48  int cproto = IpcpInfo.his_compproto >> 16;
49
50#ifdef DEBUG
51  logprintf("SendPppFrame: proto = %x\n", IpcpInfo.his_compproto);
52#endif
53  if (cproto== PROTO_VJCOMP) {
54    type = sl_compress_tcp(bp, (struct ip *)MBUF_CTOP(bp), &cslc, IpcpInfo.his_compproto & 0xff);
55
56#ifdef DEBUG
57    logprintf("type = %x\n", type);
58#endif
59    switch (type) {
60    case TYPE_IP:
61      proto = PROTO_IP;
62      break;
63    case TYPE_UNCOMPRESSED_TCP:
64      proto = PROTO_VJUNCOMP;
65      break;
66    case TYPE_COMPRESSED_TCP:
67      proto = PROTO_VJCOMP;
68      break;
69    default:
70      logprintf("unknown type %x\n", type);
71      pfree(bp);
72      return;
73    }
74  } else
75    proto = PROTO_IP;
76  HdlcOutput(PRI_NORMAL, proto, bp);
77}
78
79static struct mbuf *
80VjUncompressTcp(bp, type)
81struct mbuf *bp;
82u_char type;
83{
84  u_char *bufp;
85  int len, olen, rlen;
86  struct mbuf *nbp;
87  u_char work[MAX_HDR+MAX_VJHEADER];   /* enough to hold TCP/IP header */
88
89  olen = len = plength(bp);
90  if (type == TYPE_UNCOMPRESSED_TCP) {
91    /*
92     * Uncompressed packet does NOT change its size, so that we can
93     * use mbuf space for uncompression job.
94     */
95    bufp = MBUF_CTOP(bp);
96    len = sl_uncompress_tcp(&bufp, len, type, &cslc);
97    if (len <= 0) {
98      pfree(bp);
99      bp = NULLBUFF;
100    }
101    return(bp);
102  }
103  /*
104   *  Handle compressed packet.
105   *    1) Read upto MAX_VJHEADER bytes into work space.
106   *	2) Try to uncompress it.
107   *    3) Compute amount of necesary space.
108   *    4) Copy unread data info there.
109   */
110  if (len > MAX_VJHEADER) len = MAX_VJHEADER;
111  rlen = len;
112  bufp = work + MAX_HDR;
113  bp = mbread(bp, bufp, rlen);
114  len = sl_uncompress_tcp(&bufp, olen, type, &cslc);
115  if (len <= 0) {
116    pfree(bp);
117    return NULLBUFF;
118  }
119  len -= olen;
120  len += rlen;
121  nbp = mballoc(len, MB_VJCOMP);
122  bcopy(bufp, MBUF_CTOP(nbp), len);
123  nbp->next = bp;
124  return(nbp);
125}
126
127struct mbuf *
128VjCompInput(bp, proto)
129struct mbuf *bp;
130int proto;
131{
132  u_char type;
133
134#ifdef DEBUG
135  logprintf("VjCompInput (%02x):\n", proto);
136  DumpBp(bp);
137#endif
138
139  switch (proto) {
140  case PROTO_VJCOMP:
141    type = TYPE_COMPRESSED_TCP;
142    break;
143  case PROTO_VJUNCOMP:
144    type = TYPE_UNCOMPRESSED_TCP;
145    break;
146  default:
147    logprintf("???\n");
148    return(bp);
149  }
150  bp = VjUncompressTcp(bp, type);
151  return(bp);
152}
153