hdlc.c revision 32381 
1/*
2 *	     PPP High Level Link Control (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 * $Id: hdlc.c,v 1.26 1998/01/06 00:58:31 brian Exp $
21 *
22 *	TODO:
23 */
24#include <sys/param.h>
25#include <netinet/in.h>
26
27#include <stdio.h>
28#include <string.h>
29#include <termios.h>
30
31#include "command.h"
32#include "mbuf.h"
33#include "log.h"
34#include "defs.h"
35#include "timer.h"
36#include "fsm.h"
37#include "hdlc.h"
38#include "lcpproto.h"
39#include "ipcp.h"
40#include "ip.h"
41#include "vjcomp.h"
42#include "pap.h"
43#include "chap.h"
44#include "lcp.h"
45#include "async.h"
46#include "lqr.h"
47#include "loadalias.h"
48#include "vars.h"
49#include "modem.h"
50#include "ccp.h"
51
52struct hdlcstat {
53  int badfcs;
54  int badaddr;
55  int badcommand;
56  int unknownproto;
57}        HdlcStat;
58
59static int ifOutPackets;
60static int ifOutOctets;
61static int ifOutLQRs;
62static int ifInPackets;
63static int ifInOctets;
64
65struct protostat {
66  u_short number;
67  const char *name;
68  u_long in_count;
69  u_long out_count;
70} ProtocolStat[] = {
71  { PROTO_IP, "IP" },
72  { PROTO_VJUNCOMP, "VJ_UNCOMP" },
73  { PROTO_VJCOMP, "VJ_COMP" },
74  { PROTO_COMPD, "COMPD" },
75  { PROTO_LCP, "LCP" },
76  { PROTO_IPCP, "IPCP" },
77  { PROTO_CCP, "CCP" },
78  { PROTO_PAP, "PAP" },
79  { PROTO_LQR, "LQR" },
80  { PROTO_CHAP, "CHAP" },
81  { 0, "Others" }
82};
83
84static u_short const fcstab[256] = {
85   /* 00 */ 0x0000, 0x1189, 0x2312, 0x329b, 0x4624, 0x57ad, 0x6536, 0x74bf,
86   /* 08 */ 0x8c48, 0x9dc1, 0xaf5a, 0xbed3, 0xca6c, 0xdbe5, 0xe97e, 0xf8f7,
87   /* 10 */ 0x1081, 0x0108, 0x3393, 0x221a, 0x56a5, 0x472c, 0x75b7, 0x643e,
88   /* 18 */ 0x9cc9, 0x8d40, 0xbfdb, 0xae52, 0xdaed, 0xcb64, 0xf9ff, 0xe876,
89   /* 20 */ 0x2102, 0x308b, 0x0210, 0x1399, 0x6726, 0x76af, 0x4434, 0x55bd,
90   /* 28 */ 0xad4a, 0xbcc3, 0x8e58, 0x9fd1, 0xeb6e, 0xfae7, 0xc87c, 0xd9f5,
91   /* 30 */ 0x3183, 0x200a, 0x1291, 0x0318, 0x77a7, 0x662e, 0x54b5, 0x453c,
92   /* 38 */ 0xbdcb, 0xac42, 0x9ed9, 0x8f50, 0xfbef, 0xea66, 0xd8fd, 0xc974,
93   /* 40 */ 0x4204, 0x538d, 0x6116, 0x709f, 0x0420, 0x15a9, 0x2732, 0x36bb,
94   /* 48 */ 0xce4c, 0xdfc5, 0xed5e, 0xfcd7, 0x8868, 0x99e1, 0xab7a, 0xbaf3,
95   /* 50 */ 0x5285, 0x430c, 0x7197, 0x601e, 0x14a1, 0x0528, 0x37b3, 0x263a,
96   /* 58 */ 0xdecd, 0xcf44, 0xfddf, 0xec56, 0x98e9, 0x8960, 0xbbfb, 0xaa72,
97   /* 60 */ 0x6306, 0x728f, 0x4014, 0x519d, 0x2522, 0x34ab, 0x0630, 0x17b9,
98   /* 68 */ 0xef4e, 0xfec7, 0xcc5c, 0xddd5, 0xa96a, 0xb8e3, 0x8a78, 0x9bf1,
99   /* 70 */ 0x7387, 0x620e, 0x5095, 0x411c, 0x35a3, 0x242a, 0x16b1, 0x0738,
100   /* 78 */ 0xffcf, 0xee46, 0xdcdd, 0xcd54, 0xb9eb, 0xa862, 0x9af9, 0x8b70,
101   /* 80 */ 0x8408, 0x9581, 0xa71a, 0xb693, 0xc22c, 0xd3a5, 0xe13e, 0xf0b7,
102   /* 88 */ 0x0840, 0x19c9, 0x2b52, 0x3adb, 0x4e64, 0x5fed, 0x6d76, 0x7cff,
103   /* 90 */ 0x9489, 0x8500, 0xb79b, 0xa612, 0xd2ad, 0xc324, 0xf1bf, 0xe036,
104   /* 98 */ 0x18c1, 0x0948, 0x3bd3, 0x2a5a, 0x5ee5, 0x4f6c, 0x7df7, 0x6c7e,
105   /* a0 */ 0xa50a, 0xb483, 0x8618, 0x9791, 0xe32e, 0xf2a7, 0xc03c, 0xd1b5,
106   /* a8 */ 0x2942, 0x38cb, 0x0a50, 0x1bd9, 0x6f66, 0x7eef, 0x4c74, 0x5dfd,
107   /* b0 */ 0xb58b, 0xa402, 0x9699, 0x8710, 0xf3af, 0xe226, 0xd0bd, 0xc134,
108   /* b8 */ 0x39c3, 0x284a, 0x1ad1, 0x0b58, 0x7fe7, 0x6e6e, 0x5cf5, 0x4d7c,
109   /* c0 */ 0xc60c, 0xd785, 0xe51e, 0xf497, 0x8028, 0x91a1, 0xa33a, 0xb2b3,
110   /* c8 */ 0x4a44, 0x5bcd, 0x6956, 0x78df, 0x0c60, 0x1de9, 0x2f72, 0x3efb,
111   /* d0 */ 0xd68d, 0xc704, 0xf59f, 0xe416, 0x90a9, 0x8120, 0xb3bb, 0xa232,
112   /* d8 */ 0x5ac5, 0x4b4c, 0x79d7, 0x685e, 0x1ce1, 0x0d68, 0x3ff3, 0x2e7a,
113   /* e0 */ 0xe70e, 0xf687, 0xc41c, 0xd595, 0xa12a, 0xb0a3, 0x8238, 0x93b1,
114   /* e8 */ 0x6b46, 0x7acf, 0x4854, 0x59dd, 0x2d62, 0x3ceb, 0x0e70, 0x1ff9,
115   /* f0 */ 0xf78f, 0xe606, 0xd49d, 0xc514, 0xb1ab, 0xa022, 0x92b9, 0x8330,
116   /* f8 */ 0x7bc7, 0x6a4e, 0x58d5, 0x495c, 0x3de3, 0x2c6a, 0x1ef1, 0x0f78
117};
118
119u_char EscMap[33];
120
121void
122HdlcInit()
123{
124  ifInOctets = ifOutOctets = 0;
125  ifInPackets = ifOutPackets = 0;
126  ifOutLQRs = 0;
127}
128
129/*
130 *  HDLC FCS computation. Read RFC 1171 Appendix B and CCITT X.25 section
131 *  2.27 for further details.
132 */
133inline u_short
134HdlcFcs(u_short fcs, u_char * cp, int len)
135{
136  while (len--)
137    fcs = (fcs >> 8) ^ fcstab[(fcs ^ *cp++) & 0xff];
138  return (fcs);
139}
140
141inline u_short
142HdlcFcsBuf(u_short fcs, struct mbuf *m)
143{
144  int len;
145  u_char *pos, *end;
146
147  len = plength(m);
148  pos = MBUF_CTOP(m);
149  end = pos + m->cnt;
150  while (len--) {
151    fcs = (fcs >> 8) ^ fcstab[(fcs ^ *pos++) & 0xff];
152    if (pos == end && len) {
153      m = m->next;
154      pos = MBUF_CTOP(m);
155      end = pos + m->cnt;
156    }
157  }
158  return (fcs);
159}
160
161void
162HdlcOutput(int pri, u_short proto, struct mbuf * bp)
163{
164  struct mbuf *mhp, *mfcs;
165  struct protostat *statp;
166  struct lqrdata *lqr;
167  u_char *cp;
168  u_short fcs;
169
170  if ((proto & 0xfff1) == 0x21)		/* Network Layer protocol */
171    if (CcpFsm.state == ST_OPENED)
172      if (CcpOutput(pri, proto, bp))
173        return;
174
175  if (DEV_IS_SYNC)
176    mfcs = NULLBUFF;
177  else
178    mfcs = mballoc(2, MB_HDLCOUT);
179
180  mhp = mballoc(4, MB_HDLCOUT);
181  mhp->cnt = 0;
182  cp = MBUF_CTOP(mhp);
183  if (proto == PROTO_LCP || LcpInfo.his_acfcomp == 0) {
184    *cp++ = HDLC_ADDR;
185    *cp++ = HDLC_UI;
186    mhp->cnt += 2;
187  }
188
189  /*
190   * If possible, compress protocol field.
191   */
192  if (LcpInfo.his_protocomp && (proto & 0xff00) == 0) {
193    *cp++ = proto;
194    mhp->cnt++;
195  } else {
196    *cp++ = proto >> 8;
197    *cp = proto & 0377;
198    mhp->cnt += 2;
199  }
200  mhp->next = bp;
201  while (bp->next != NULL)
202    bp = bp->next;
203  bp->next = mfcs;
204  bp = mhp->next;
205
206  lqr = &MyLqrData;
207  lqr->PeerOutPackets = ifOutPackets++;
208  ifOutOctets += plength(mhp) + 1;
209  lqr->PeerOutOctets = ifOutOctets;
210
211  if (proto == PROTO_LQR) {
212    lqr->MagicNumber = LcpInfo.want_magic;
213    lqr->LastOutLQRs = HisLqrData.PeerOutLQRs;
214    lqr->LastOutPackets = HisLqrData.PeerOutPackets;
215    lqr->LastOutOctets = HisLqrData.PeerOutOctets;
216    lqr->PeerInLQRs = HisLqrSave.SaveInLQRs;
217    lqr->PeerInPackets = HisLqrSave.SaveInPackets;
218    lqr->PeerInDiscards = HisLqrSave.SaveInDiscards;
219    lqr->PeerInErrors = HisLqrSave.SaveInErrors;
220    lqr->PeerInOctets = HisLqrSave.SaveInOctets;
221    lqr->PeerOutLQRs = ++ifOutLQRs;
222    LqrDump("LqrOutput", lqr);
223    LqrChangeOrder(lqr, (struct lqrdata *) (MBUF_CTOP(bp)));
224  }
225  if (!DEV_IS_SYNC) {
226    mfcs->cnt = 0;
227    fcs = HdlcFcsBuf(INITFCS, mhp);
228    fcs = ~fcs;
229    cp = MBUF_CTOP(mfcs);
230    *cp++ = fcs & 0377;		/* Low byte first!! */
231    *cp++ = fcs >> 8;
232    mfcs->cnt = 2;
233  }
234  LogDumpBp(LogHDLC, "HdlcOutput", mhp);
235  for (statp = ProtocolStat; statp->number; statp++)
236    if (statp->number == proto)
237      break;
238  statp->out_count++;
239
240  LogPrintf(LogDEBUG, "HdlcOutput: proto = 0x%04x\n", proto);
241
242  if (DEV_IS_SYNC)
243    ModemOutput(pri, mhp);
244  else
245    AsyncOutput(pri, mhp, proto);
246}
247
248/* Check out the latest ``Assigned numbers'' rfc (rfc1700.txt) */
249static struct {
250  u_short from;
251  u_short to;
252  const char *name;
253} protocols[] = {
254  { 0x0001, 0x0001, "Padding Protocol" },
255  { 0x0003, 0x001f, "reserved (transparency inefficient)" },
256  { 0x0021, 0x0021, "Internet Protocol" },
257  { 0x0023, 0x0023, "OSI Network Layer" },
258  { 0x0025, 0x0025, "Xerox NS IDP" },
259  { 0x0027, 0x0027, "DECnet Phase IV" },
260  { 0x0029, 0x0029, "Appletalk" },
261  { 0x002b, 0x002b, "Novell IPX" },
262  { 0x002d, 0x002d, "Van Jacobson Compressed TCP/IP" },
263  { 0x002f, 0x002f, "Van Jacobson Uncompressed TCP/IP" },
264  { 0x0031, 0x0031, "Bridging PDU" },
265  { 0x0033, 0x0033, "Stream Protocol (ST-II)" },
266  { 0x0035, 0x0035, "Banyan Vines" },
267  { 0x0037, 0x0037, "reserved (until 1993)" },
268  { 0x0039, 0x0039, "AppleTalk EDDP" },
269  { 0x003b, 0x003b, "AppleTalk SmartBuffered" },
270  { 0x003d, 0x003d, "Multi-Link" },
271  { 0x003f, 0x003f, "NETBIOS Framing" },
272  { 0x0041, 0x0041, "Cisco Systems" },
273  { 0x0043, 0x0043, "Ascom Timeplex" },
274  { 0x0045, 0x0045, "Fujitsu Link Backup and Load Balancing (LBLB)" },
275  { 0x0047, 0x0047, "DCA Remote Lan" },
276  { 0x0049, 0x0049, "Serial Data Transport Protocol (PPP-SDTP)" },
277  { 0x004b, 0x004b, "SNA over 802.2" },
278  { 0x004d, 0x004d, "SNA" },
279  { 0x004f, 0x004f, "IP6 Header Compression" },
280  { 0x0051, 0x0051, "KNX Bridging Data" },
281  { 0x0053, 0x0053, "Encryption" },
282  { 0x0055, 0x0055, "Individual Link Encryption" },
283  { 0x006f, 0x006f, "Stampede Bridging" },
284  { 0x0071, 0x0071, "BAP Bandwidth Allocation Protocol" },
285  { 0x0073, 0x0073, "MP+ Protocol" },
286  { 0x007d, 0x007d, "reserved (Control Escape)" },
287  { 0x007f, 0x007f, "reserved (compression inefficient)" },
288  { 0x00cf, 0x00cf, "reserved (PPP NLPID)" },
289  { 0x00fb, 0x00fb, "compression on single link in multilink group" },
290  { 0x00fd, 0x00fd, "1st choice compression" },
291  { 0x00ff, 0x00ff, "reserved (compression inefficient)" },
292  { 0x0200, 0x02ff, "(compression inefficient)" },
293  { 0x0201, 0x0201, "802.1d Hello Packets" },
294  { 0x0203, 0x0203, "IBM Source Routing BPDU" },
295  { 0x0205, 0x0205, "DEC LANBridge100 Spanning Tree" },
296  { 0x0207, 0x0207, "Cisco Discovery Protocol" },
297  { 0x0209, 0x0209, "Netcs Twin Routing" },
298  { 0x0231, 0x0231, "Luxcom" },
299  { 0x0233, 0x0233, "Sigma Network Systems" },
300  { 0x0235, 0x0235, "Apple Client Server Protocol" },
301  { 0x1e00, 0x1eff, "(compression inefficient)" },
302  { 0x4001, 0x4001, "Cray Communications Control Protocol" },
303  { 0x4003, 0x4003, "CDPD Mobile Network Registration Protocol" },
304  { 0x4021, 0x4021, "Stacker LZS" },
305  { 0x8001, 0x801f, "Not Used - reserved" },
306  { 0x8021, 0x8021, "Internet Protocol Control Protocol" },
307  { 0x8023, 0x8023, "OSI Network Layer Control Protocol" },
308  { 0x8025, 0x8025, "Xerox NS IDP Control Protocol" },
309  { 0x8027, 0x8027, "DECnet Phase IV Control Protocol" },
310  { 0x8029, 0x8029, "Appletalk Control Protocol" },
311  { 0x802b, 0x802b, "Novell IPX Control Protocol" },
312  { 0x802d, 0x802d, "reserved" },
313  { 0x802f, 0x802f, "reserved" },
314  { 0x8031, 0x8031, "Bridging NCP" },
315  { 0x8033, 0x8033, "Stream Protocol Control Protocol" },
316  { 0x8035, 0x8035, "Banyan Vines Control Protocol" },
317  { 0x8037, 0x8037, "reserved till 1993" },
318  { 0x8039, 0x8039, "reserved" },
319  { 0x803b, 0x803b, "reserved" },
320  { 0x803d, 0x803d, "Multi-Link Control Protocol" },
321  { 0x803f, 0x803f, "NETBIOS Framing Control Protocol" },
322  { 0x8041, 0x8041, "Cisco Systems Control Protocol" },
323  { 0x8043, 0x8043, "Ascom Timeplex" },
324  { 0x8045, 0x8045, "Fujitsu LBLB Control Protocol" },
325  { 0x8047, 0x8047, "DCA Remote Lan Network Control Protocol (RLNCP)" },
326  { 0x8049, 0x8049, "Serial Data Control Protocol (PPP-SDCP)" },
327  { 0x804b, 0x804b, "SNA over 802.2 Control Protocol" },
328  { 0x804d, 0x804d, "SNA Control Protocol" },
329  { 0x804f, 0x804f, "IP6 Header Compression Control Protocol" },
330  { 0x8051, 0x8051, "KNX Bridging Control Protocol" },
331  { 0x8053, 0x8053, "Encryption Control Protocol" },
332  { 0x8055, 0x8055, "Individual Link Encryption Control Protocol" },
333  { 0x806f, 0x806f, "Stampede Bridging Control Protocol" },
334  { 0x8073, 0x8073, "MP+ Control Protocol" },
335  { 0x8071, 0x8071, "BACP Bandwidth Allocation Control Protocol" },
336  { 0x807d, 0x807d, "Not Used - reserved" },
337  { 0x80cf, 0x80cf, "Not Used - reserved" },
338  { 0x80fb, 0x80fb, "compression on single link in multilink group control" },
339  { 0x80fd, 0x80fd, "Compression Control Protocol" },
340  { 0x80ff, 0x80ff, "Not Used - reserved" },
341  { 0x8207, 0x8207, "Cisco Discovery Protocol Control" },
342  { 0x8209, 0x8209, "Netcs Twin Routing" },
343  { 0x8235, 0x8235, "Apple Client Server Protocol Control" },
344  { 0xc021, 0xc021, "Link Control Protocol" },
345  { 0xc023, 0xc023, "Password Authentication Protocol" },
346  { 0xc025, 0xc025, "Link Quality Report" },
347  { 0xc027, 0xc027, "Shiva Password Authentication Protocol" },
348  { 0xc029, 0xc029, "CallBack Control Protocol (CBCP)" },
349  { 0xc081, 0xc081, "Container Control Protocol" },
350  { 0xc223, 0xc223, "Challenge Handshake Authentication Protocol" },
351  { 0xc225, 0xc225, "RSA Authentication Protocol" },
352  { 0xc227, 0xc227, "Extensible Authentication Protocol" },
353  { 0xc26f, 0xc26f, "Stampede Bridging Authorization Protocol" },
354  { 0xc281, 0xc281, "Proprietary Authentication Protocol" },
355  { 0xc283, 0xc283, "Proprietary Authentication Protocol" },
356  { 0xc481, 0xc481, "Proprietary Node ID Authentication Protocol" }
357};
358
359#define NPROTOCOLS (sizeof protocols/sizeof protocols[0])
360
361static const char *
362Protocol2Nam(u_short proto)
363{
364  int f;
365
366  for (f = 0; f < NPROTOCOLS; f++)
367    if (proto >= protocols[f].from && proto <= protocols[f].to)
368      return protocols[f].name;
369    else if (proto < protocols[f].from)
370      break;
371  return "unrecognised protocol";
372}
373
374void
375DecodePacket(u_short proto, struct mbuf * bp)
376{
377  u_char *cp;
378
379  LogPrintf(LogDEBUG, "DecodePacket: proto = 0x%04x\n", proto);
380
381  /*
382   * If proto isn't PROTO_COMPD, we still want to pass it to the
383   * decompression routines so that the dictionary's updated
384   */
385  if (CcpFsm.state == ST_OPENED)
386    if (proto == PROTO_COMPD) {
387      if ((bp = CompdInput(&proto, bp)) == NULL)
388        return;
389    } else if ((proto & 0xfff1) == 0x21)	/* Network Layer protocol */
390      CcpDictSetup(proto, bp);
391
392  switch (proto) {
393  case PROTO_LCP:
394    LcpInput(bp);
395    break;
396  case PROTO_PAP:
397    PapInput(bp);
398    break;
399  case PROTO_LQR:
400    HisLqrSave.SaveInLQRs++;
401    LqrInput(bp);
402    break;
403  case PROTO_CHAP:
404    ChapInput(bp);
405    break;
406  case PROTO_VJUNCOMP:
407  case PROTO_VJCOMP:
408    bp = VjCompInput(bp, proto);
409    if (bp == NULLBUFF) {
410      break;
411    }
412    /* fall down */
413  case PROTO_IP:
414    IpInput(bp);
415    break;
416  case PROTO_IPCP:
417    IpcpInput(bp);
418    break;
419  case PROTO_CCP:
420    CcpInput(bp);
421    break;
422  default:
423    LogPrintf(LogPHASE, "Unknown protocol 0x%04x (%s)\n",
424              proto, Protocol2Nam(proto));
425    bp->offset -= 2;
426    bp->cnt += 2;
427    cp = MBUF_CTOP(bp);
428    LcpSendProtoRej(cp, bp->cnt);
429    HisLqrSave.SaveInDiscards++;
430    HdlcStat.unknownproto++;
431    pfree(bp);
432    break;
433  }
434}
435
436int
437ReportProtStatus(struct cmdargs const *arg)
438{
439  struct protostat *statp;
440  int cnt;
441
442  statp = ProtocolStat;
443  statp--;
444  cnt = 0;
445  fprintf(VarTerm, "    Protocol     in        out      Protocol      in       out\n");
446  do {
447    statp++;
448    fprintf(VarTerm, "   %-9s: %8lu, %8lu",
449	    statp->name, statp->in_count, statp->out_count);
450    if (++cnt == 2) {
451      fprintf(VarTerm, "\n");
452      cnt = 0;
453    }
454  } while (statp->number);
455  if (cnt)
456    fprintf(VarTerm, "\n");
457  return (0);
458}
459
460int
461ReportHdlcStatus(struct cmdargs const *arg)
462{
463  struct hdlcstat *hp = &HdlcStat;
464
465  if (VarTerm) {
466    fprintf(VarTerm, "HDLC level errors\n\n");
467    fprintf(VarTerm, "FCS: %u  ADDR: %u  COMMAND: %u  PROTO: %u\n",
468	    hp->badfcs, hp->badaddr, hp->badcommand, hp->unknownproto);
469  }
470  return 0;
471}
472
473static struct hdlcstat laststat;
474
475void
476HdlcErrorCheck()
477{
478  struct hdlcstat *hp = &HdlcStat;
479  struct hdlcstat *op = &laststat;
480
481  if (memcmp(hp, op, sizeof laststat)) {
482    LogPrintf(LogPHASE, "HDLC errors -> FCS: %u ADDR: %u COMD: %u PROTO: %u\n",
483	      hp->badfcs - op->badfcs, hp->badaddr - op->badaddr,
484      hp->badcommand - op->badcommand, hp->unknownproto - op->unknownproto);
485  }
486  laststat = HdlcStat;
487}
488
489void
490HdlcInput(struct mbuf * bp)
491{
492  u_short fcs, proto;
493  u_char *cp, addr, ctrl;
494  struct protostat *statp;
495
496  LogDumpBp(LogHDLC, "HdlcInput:", bp);
497  if (DEV_IS_SYNC)
498    fcs = GOODFCS;
499  else
500    fcs = HdlcFcs(INITFCS, MBUF_CTOP(bp), bp->cnt);
501  HisLqrSave.SaveInOctets += bp->cnt + 1;
502
503  LogPrintf(LogDEBUG, "HdlcInput: fcs = %04x (%s)\n",
504	    fcs, (fcs == GOODFCS) ? "good" : "bad");
505  if (fcs != GOODFCS) {
506    HisLqrSave.SaveInErrors++;
507    LogPrintf(LogDEBUG, "HdlcInput: Bad FCS\n");
508    HdlcStat.badfcs++;
509    pfree(bp);
510    return;
511  }
512  if (!DEV_IS_SYNC)
513    bp->cnt -= 2;		/* discard FCS part */
514
515  if (bp->cnt < 2) {		/* XXX: raise this bar ? */
516    pfree(bp);
517    return;
518  }
519  cp = MBUF_CTOP(bp);
520
521  ifInPackets++;
522  ifInOctets += bp->cnt;
523
524  if (!LcpInfo.want_acfcomp) {
525
526    /*
527     * We expect that packet is not compressed.
528     */
529    addr = *cp++;
530    if (addr != HDLC_ADDR) {
531      HisLqrSave.SaveInErrors++;
532      HdlcStat.badaddr++;
533      LogPrintf(LogDEBUG, "HdlcInput: addr %02x\n", *cp);
534      pfree(bp);
535      return;
536    }
537    ctrl = *cp++;
538    if (ctrl != HDLC_UI) {
539      HisLqrSave.SaveInErrors++;
540      HdlcStat.badcommand++;
541      LogPrintf(LogDEBUG, "HdlcInput: %02x\n", *cp);
542      pfree(bp);
543      return;
544    }
545    bp->offset += 2;
546    bp->cnt -= 2;
547  } else if (cp[0] == HDLC_ADDR && cp[1] == HDLC_UI) {
548
549    /*
550     * We can receive compressed packet, but peer still send uncompressed
551     * packet to me.
552     */
553    cp += 2;
554    bp->offset += 2;
555    bp->cnt -= 2;
556  }
557  if (LcpInfo.want_protocomp) {
558    proto = 0;
559    cp--;
560    do {
561      cp++;
562      bp->offset++;
563      bp->cnt--;
564      proto = proto << 8;
565      proto += *cp;
566    } while (!(proto & 1));
567  } else {
568    proto = *cp++ << 8;
569    proto |= *cp++;
570    bp->offset += 2;
571    bp->cnt -= 2;
572  }
573
574  for (statp = ProtocolStat; statp->number; statp++)
575    if (statp->number == proto)
576      break;
577  statp->in_count++;
578  HisLqrSave.SaveInPackets++;
579
580  DecodePacket(proto, bp);
581}
582