async.c revision 50479 
1/*
2 *	             PPP Async HDLC Module
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 * $FreeBSD: head/usr.sbin/ppp/async.c 50479 1999-08-28 01:35:59Z peter $
21 *
22 */
23#include <sys/types.h>
24
25#include <string.h>
26#include <termios.h>
27
28#include "layer.h"
29#include "mbuf.h"
30#include "log.h"
31#include "defs.h"
32#include "timer.h"
33#include "fsm.h"
34#include "lqr.h"
35#include "hdlc.h"
36#include "lcp.h"
37#include "proto.h"
38#include "async.h"
39#include "throughput.h"
40#include "ccp.h"
41#include "link.h"
42#include "descriptor.h"
43#include "physical.h"
44
45#define MODE_HUNT 0x01
46#define MODE_ESC  0x02
47
48void
49async_Init(struct async *async)
50{
51  async->mode = MODE_HUNT;
52  async->length = 0;
53  async->my_accmap = async->his_accmap = 0xffffffff;
54  memset(async->cfg.EscMap, '\0', sizeof async->cfg.EscMap);
55}
56
57void
58async_SetLinkParams(struct async *async, struct lcp *lcp)
59{
60  async->my_accmap = lcp->want_accmap;
61  async->his_accmap = lcp->his_accmap | lcp->want_accmap;
62}
63
64/*
65 * Encode into async HDLC byte code
66 */
67static void
68async_Encode(struct async *async, u_char **cp, u_char c, int proto)
69{
70  u_char *wp;
71
72  wp = *cp;
73  if ((c < 0x20 && (proto == PROTO_LCP || (async->his_accmap & (1 << c))))
74      || (c == HDLC_ESC) || (c == HDLC_SYN)) {
75    *wp++ = HDLC_ESC;
76    c ^= HDLC_XOR;
77  }
78  if (async->cfg.EscMap[32] && async->cfg.EscMap[c >> 3] & (1 << (c & 7))) {
79    *wp++ = HDLC_ESC;
80    c ^= HDLC_XOR;
81  }
82  *wp++ = c;
83  *cp = wp;
84}
85
86static struct mbuf *
87async_LayerPush(struct bundle *bundle, struct link *l, struct mbuf *bp,
88                int pri, u_short *proto)
89{
90  struct physical *p = link2physical(l);
91  u_char *cp, *sp, *ep;
92  struct mbuf *wp;
93  int cnt;
94
95  if (!p || mbuf_Length(bp) > HDLCSIZE) {
96    mbuf_Free(bp);
97    return NULL;
98  }
99
100  cp = p->async.xbuff;
101  ep = cp + HDLCSIZE - 10;
102  wp = bp;
103  *cp++ = HDLC_SYN;
104  while (wp) {
105    sp = MBUF_CTOP(wp);
106    for (cnt = wp->cnt; cnt > 0; cnt--) {
107      async_Encode(&p->async, &cp, *sp++, *proto);
108      if (cp >= ep) {
109	mbuf_Free(bp);
110	return NULL;
111      }
112    }
113    wp = wp->next;
114  }
115  *cp++ = HDLC_SYN;
116
117  cnt = cp - p->async.xbuff;
118  mbuf_Free(bp);
119  bp = mbuf_Alloc(cnt, MB_ASYNCOUT);
120  memcpy(MBUF_CTOP(bp), p->async.xbuff, cnt);
121  log_DumpBp(LogASYNC, "Write", bp);
122
123  return bp;
124}
125
126static struct mbuf *
127async_Decode(struct async *async, u_char c)
128{
129  struct mbuf *bp;
130
131  if ((async->mode & MODE_HUNT) && c != HDLC_SYN)
132    return NULL;
133
134  switch (c) {
135  case HDLC_SYN:
136    async->mode &= ~MODE_HUNT;
137    if (async->length) {		/* packet is ready. */
138      bp = mbuf_Alloc(async->length, MB_ASYNCIN);
139      mbuf_Write(bp, async->hbuff, async->length);
140      async->length = 0;
141      return bp;
142    }
143    break;
144  case HDLC_ESC:
145    if (!(async->mode & MODE_ESC)) {
146      async->mode |= MODE_ESC;
147      break;
148    }
149    /* Fall into ... */
150  default:
151    if (async->length >= HDLCSIZE) {
152      /* packet is too large, discard it */
153      log_Printf(LogWARN, "Packet too large (%d), discarding.\n",
154                 async->length);
155      async->length = 0;
156      async->mode = MODE_HUNT;
157      break;
158    }
159    if (async->mode & MODE_ESC) {
160      c ^= HDLC_XOR;
161      async->mode &= ~MODE_ESC;
162    }
163    async->hbuff[async->length++] = c;
164    break;
165  }
166  return NULL;
167}
168
169static struct mbuf *
170async_LayerPull(struct bundle *b, struct link *l, struct mbuf *bp,
171                u_short *proto)
172{
173  struct mbuf *nbp, **last;
174  struct physical *p = link2physical(l);
175  u_char *ch;
176  size_t cnt;
177
178  if (!p) {
179    log_Printf(LogERROR, "Can't Pull an async packet from a logical link\n");
180    return bp;
181  }
182
183  last = &nbp;
184
185  log_DumpBp(LogASYNC, "Read", bp);
186  while (bp) {
187    ch = MBUF_CTOP(bp);
188    for (cnt = bp->cnt; cnt; cnt--) {
189      *last = async_Decode(&p->async, *ch++);
190      if (*last != NULL)
191        last = &(*last)->pnext;
192    }
193    bp = mbuf_FreeSeg(bp);
194  }
195
196  return nbp;
197}
198
199struct layer asynclayer =
200  { LAYER_ASYNC, "async", async_LayerPush, async_LayerPull };
201