The Tcpdump Group git mirrors - tcpdump/blob - print-chdlc.c

   1 /*
   2  * Copyright (c) 1990, 1991, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 /* \summary: Cisco HDLC printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include "netdissect-stdinc.h"
  29
  30 #include "netdissect.h"
  31 #include "addrtoname.h"
  32 #include "ethertype.h"
  33 #include "extract.h"
  34 #include "chdlc.h"
  35 #include "nlpid.h"
  36
  37 static void chdlc_slarp_print(netdissect_options *, const u_char *, u_int);
  38
  39 static const struct tok chdlc_cast_values[] = {
  40     { CHDLC_UNICAST, "unicast" },
  41     { CHDLC_BCAST, "bcast" },
  42     { 0, NULL}
  43 };
  44
  45
  46 /* Standard CHDLC printer */
  47 void
  48 chdlc_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
  49 {
  50         ndo->ndo_protocol = "chdlc";
  51         ndo->ndo_ll_hdr_len += chdlc_print(ndo, p, h->len);
  52 }
  53
  54 u_int
  55 chdlc_print(netdissect_options *ndo, const u_char *p, u_int length)
  56 {
  57         u_int proto;
  58         const u_char *bp = p;
  59
  60         ndo->ndo_protocol = "chdlc";
  61         if (length < CHDLC_HDRLEN)
  62                 goto trunc;
  63         proto = GET_BE_U_2(p + 2);
  64         if (ndo->ndo_eflag) {
  65                 ND_PRINT("%s, ethertype %s (0x%04x), length %u: ",
  66                        tok2str(chdlc_cast_values, "0x%02x", GET_U_1(p)),
  67                        tok2str(ethertype_values, "Unknown", proto),
  68                        proto,
  69                        length);
  70         }
  71
  72         length -= CHDLC_HDRLEN;
  73         p += CHDLC_HDRLEN;
  74
  75         switch (proto) {
  76         case ETHERTYPE_IP:
  77                 ip_print(ndo, p, length);
  78                 break;
  79         case ETHERTYPE_IPV6:
  80                 ip6_print(ndo, p, length);
  81                 break;
  82         case CHDLC_TYPE_SLARP:
  83                 chdlc_slarp_print(ndo, p, length);
  84                 break;
  85         case ETHERTYPE_MPLS:
  86         case ETHERTYPE_MPLS_MULTI:
  87                 mpls_print(ndo, p, length);
  88                 break;
  89         case ETHERTYPE_ISO:
  90                 /* is the fudge byte set ? lets verify by spotting ISO headers */
  91                 if (length < 2)
  92                     goto trunc;
  93                 if (GET_U_1(p + 1) == NLPID_CLNP ||
  94                     GET_U_1(p + 1) == NLPID_ESIS ||
  95                     GET_U_1(p + 1) == NLPID_ISIS)
  96                     isoclns_print(ndo, p + 1, length - 1);
  97                 else
  98                     isoclns_print(ndo, p, length);
  99                 break;
 100         default:
 101                 if (!ndo->ndo_eflag)
 102                         ND_PRINT("unknown CHDLC protocol (0x%04x)", proto);
 103                 break;
 104         }
 105
 106         return (CHDLC_HDRLEN);
 107
 108 trunc:
 109         nd_print_trunc(ndo);
 110         return (ND_BYTES_AVAILABLE_AFTER(bp));
 111 }
 112
 113 /*
 114  * The fixed-length portion of a SLARP packet.
 115  */
 116 struct cisco_slarp {
 117         nd_uint32_t code;
 118 #define SLARP_REQUEST   0
 119 #define SLARP_REPLY     1
 120 #define SLARP_KEEPALIVE 2
 121         union {
 122                 struct {
 123                         uint8_t addr[4];
 124                         uint8_t mask[4];
 125                 } addr;
 126                 struct {
 127                         nd_uint32_t myseq;
 128                         nd_uint32_t yourseq;
 129                         nd_uint16_t rel;
 130                 } keep;
 131         } un;
 132 };
 133
 134 #define SLARP_MIN_LEN   14
 135 #define SLARP_MAX_LEN   18
 136
 137 static void
 138 chdlc_slarp_print(netdissect_options *ndo, const u_char *cp, u_int length)
 139 {
 140         const struct cisco_slarp *slarp;
 141         u_int sec,min,hrs,days;
 142
 143         ndo->ndo_protocol = "chdlc_slarp";
 144         ND_PRINT("SLARP (length: %u), ",length);
 145         if (length < SLARP_MIN_LEN)
 146                 goto trunc;
 147
 148         slarp = (const struct cisco_slarp *)cp;
 149         ND_TCHECK_LEN(slarp, SLARP_MIN_LEN);
 150         switch (GET_BE_U_4(slarp->code)) {
 151         case SLARP_REQUEST:
 152                 ND_PRINT("request");
 153                 /*
 154                  * At least according to William "Chops" Westfield's
 155                  * message in
 156                  *
 157                  *      https://web.archive.org/web/20190725151313/www.nethelp.no/net/cisco-hdlc.txt
 158                  *
 159                  * the address and mask aren't used in requests -
 160                  * they're just zero.
 161                  */
 162                 break;
 163         case SLARP_REPLY:
 164                 ND_PRINT("reply %s/%s",
 165                         GET_IPADDR_STRING(slarp->un.addr.addr),
 166                         GET_IPADDR_STRING(slarp->un.addr.mask));
 167                 break;
 168         case SLARP_KEEPALIVE:
 169                 ND_PRINT("keepalive: mineseen=0x%08x, yourseen=0x%08x, reliability=0x%04x",
 170                        GET_BE_U_4(slarp->un.keep.myseq),
 171                        GET_BE_U_4(slarp->un.keep.yourseq),
 172                        GET_BE_U_2(slarp->un.keep.rel));
 173
 174                 if (length >= SLARP_MAX_LEN) { /* uptime-stamp is optional */
 175                         cp += SLARP_MIN_LEN;
 176                         sec = GET_BE_U_4(cp) / 1000;
 177                         min = sec / 60; sec -= min * 60;
 178                         hrs = min / 60; min -= hrs * 60;
 179                         days = hrs / 24; hrs -= days * 24;
 180                         ND_PRINT(", link uptime=%ud%uh%um%us",days,hrs,min,sec);
 181                 }
 182                 break;
 183         default:
 184                 ND_PRINT("0x%02x unknown", GET_BE_U_4(slarp->code));
 185                 if (ndo->ndo_vflag <= 1)
 186                     print_unknown_data(ndo,cp+4,"\n\t",length-4);
 187                 break;
 188         }
 189
 190         if (SLARP_MAX_LEN < length && ndo->ndo_vflag)
 191                 ND_PRINT(", (trailing junk: %u bytes)", length - SLARP_MAX_LEN);
 192         if (ndo->ndo_vflag > 1)
 193             print_unknown_data(ndo,cp+4,"\n\t",length-4);
 194         return;
 195
 196 trunc:
 197         nd_print_trunc(ndo);
 198 }