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

   1 /*
   2  * Copyright (c) 1989, 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: Compressed Serial Line Internet Protocol 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 "extract.h"
  32
  33 #include "ip.h"
  34 #include "tcp.h"
  35 #include "slcompress.h"
  36
  37 /*
  38  * definitions of the pseudo- link-level header attached to slip
  39  * packets grabbed by the packet filter (bpf) traffic monitor.
  40  */
  41 #define SLIP_HDRLEN 16
  42
  43 #define SLX_DIR 0
  44 #define SLX_CHDR 1
  45 #define CHDR_LEN 15
  46
  47 #define SLIPDIR_IN 0
  48 #define SLIPDIR_OUT 1
  49
  50
  51 static u_int lastlen[2][256];
  52 static u_int lastconn = 255;
  53
  54 static int sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
  55 static int compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
  56
  57 u_int
  58 sl_if_print(netdissect_options *ndo,
  59             const struct pcap_pkthdr *h, const u_char *p)
  60 {
  61         u_int caplen = h->caplen;
  62         u_int length = h->len;
  63         const struct ip *ip;
  64
  65         ndo->ndo_protocol = "sl_if";
  66         if (caplen < SLIP_HDRLEN) {
  67                 nd_print_trunc(ndo);
  68                 return (caplen);
  69         }
  70
  71         caplen -= SLIP_HDRLEN;
  72         length -= SLIP_HDRLEN;
  73
  74         ip = (const struct ip *)(p + SLIP_HDRLEN);
  75
  76         if (ndo->ndo_eflag)
  77                 if (sliplink_print(ndo, p, ip, length) == -1) {
  78                         nd_print_trunc(ndo);
  79                         return (caplen + SLIP_HDRLEN);
  80                 }
  81
  82         if (caplen < 1) {
  83                 nd_print_trunc(ndo);
  84                 return (caplen + SLIP_HDRLEN);
  85         }
  86
  87         switch (IP_V(ip)) {
  88         case 4:
  89                 ip_print(ndo, (const u_char *)ip, length);
  90                 break;
  91         case 6:
  92                 ip6_print(ndo, (const u_char *)ip, length);
  93                 break;
  94         default:
  95                 ND_PRINT("ip v%u", IP_V(ip));
  96         }
  97
  98         return (SLIP_HDRLEN);
  99 }
 100
 101 u_int
 102 sl_bsdos_if_print(netdissect_options *ndo,
 103                   const struct pcap_pkthdr *h, const u_char *p)
 104 {
 105         u_int caplen = h->caplen;
 106         u_int length = h->len;
 107         const struct ip *ip;
 108
 109         ndo->ndo_protocol = "sl_bsdos_if";
 110         if (caplen < SLIP_HDRLEN) {
 111                 nd_print_trunc(ndo);
 112                 return (caplen);
 113         }
 114
 115         length -= SLIP_HDRLEN;
 116
 117         ip = (const struct ip *)(p + SLIP_HDRLEN);
 118
 119 #ifdef notdef
 120         if (ndo->ndo_eflag)
 121                 sliplink_print(ndo, p, ip, length);
 122 #endif
 123
 124         ip_print(ndo, (const u_char *)ip, length);
 125
 126         return (SLIP_HDRLEN);
 127 }
 128
 129 static int
 130 sliplink_print(netdissect_options *ndo,
 131                const u_char *p, const struct ip *ip,
 132                u_int length)
 133 {
 134         int dir;
 135         u_int hlen;
 136
 137         dir = GET_U_1(p + SLX_DIR);
 138         switch (dir) {
 139
 140         case SLIPDIR_IN:
 141                 ND_PRINT("I ");
 142                 break;
 143
 144         case SLIPDIR_OUT:
 145                 ND_PRINT("O ");
 146                 break;
 147
 148         default:
 149                 ND_PRINT("Invalid direction %d ", dir);
 150                 dir = -1;
 151                 break;
 152         }
 153         switch (GET_U_1(p + SLX_CHDR) & 0xf0) {
 154
 155         case TYPE_IP:
 156                 ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
 157                 break;
 158
 159         case TYPE_UNCOMPRESSED_TCP:
 160                 /*
 161                  * The connection id is stored in the IP protocol field.
 162                  * Get it from the link layer since sl_uncompress_tcp()
 163                  * has restored the IP header copy to IPPROTO_TCP.
 164                  */
 165                 lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
 166                 ND_PRINT("utcp %u: ", lastconn);
 167                 if (dir == -1) {
 168                         /* Direction is bogus, don't use it */
 169                         return 0;
 170                 }
 171                 ND_TCHECK_SIZE(ip);
 172                 hlen = IP_HL(ip);
 173                 ND_TCHECK_SIZE((const struct tcphdr *)&((const int *)ip)[hlen]);
 174                 hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
 175                 lastlen[dir][lastconn] = length - (hlen << 2);
 176                 break;
 177
 178         default:
 179                 if (dir == -1) {
 180                         /* Direction is bogus, don't use it */
 181                         return 0;
 182                 }
 183                 if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
 184                         if (compressed_sl_print(ndo, p + SLX_CHDR, ip,
 185                                                 length, dir) == -1)
 186                                 goto trunc;
 187                         ND_PRINT(": ");
 188                 } else
 189                         ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
 190         }
 191         return 0;
 192 trunc:
 193         return -1;
 194 }
 195
 196 static const u_char *
 197 print_sl_change(netdissect_options *ndo,
 198                 const char *str, const u_char *cp)
 199 {
 200         u_int i;
 201
 202         if ((i = GET_U_1(cp)) == 0) {
 203                 cp++;
 204                 i = GET_BE_U_2(cp);
 205                 cp += 2;
 206         }
 207         ND_PRINT(" %s%u", str, i);
 208         return (cp);
 209 }
 210
 211 static const u_char *
 212 print_sl_winchange(netdissect_options *ndo,
 213                    const u_char *cp)
 214 {
 215         int16_t i;
 216
 217         if ((i = GET_U_1(cp)) == 0) {
 218                 cp++;
 219                 i = GET_BE_S_2(cp);
 220                 cp += 2;
 221         }
 222         if (i >= 0)
 223                 ND_PRINT(" W+%d", i);
 224         else
 225                 ND_PRINT(" W%d", i);
 226         return (cp);
 227 }
 228
 229 static int
 230 compressed_sl_print(netdissect_options *ndo,
 231                     const u_char *chdr, const struct ip *ip,
 232                     u_int length, int dir)
 233 {
 234         const u_char *cp = chdr;
 235         u_int flags, hlen;
 236
 237         flags = GET_U_1(cp);
 238         cp++;
 239         if (flags & NEW_C) {
 240                 lastconn = GET_U_1(cp);
 241                 cp++;
 242                 ND_PRINT("ctcp %u", lastconn);
 243         } else
 244                 ND_PRINT("ctcp *");
 245
 246         /* skip tcp checksum */
 247         cp += 2;
 248
 249         switch (flags & SPECIALS_MASK) {
 250         case SPECIAL_I:
 251                 ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
 252                 break;
 253
 254         case SPECIAL_D:
 255                 ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
 256                 break;
 257
 258         default:
 259                 if (flags & NEW_U)
 260                         cp = print_sl_change(ndo, "U=", cp);
 261                 if (flags & NEW_W)
 262                         cp = print_sl_winchange(ndo, cp);
 263                 if (flags & NEW_A)
 264                         cp = print_sl_change(ndo, "A+", cp);
 265                 if (flags & NEW_S)
 266                         cp = print_sl_change(ndo, "S+", cp);
 267                 break;
 268         }
 269         if (flags & NEW_I)
 270                 cp = print_sl_change(ndo, "I+", cp);
 271
 272         /*
 273          * 'hlen' is the length of the uncompressed TCP/IP header (in words).
 274          * 'cp - chdr' is the length of the compressed header.
 275          * 'length - hlen' is the amount of data in the packet.
 276          */
 277         ND_TCHECK_SIZE(ip);
 278         hlen = IP_HL(ip);
 279         ND_TCHECK_SIZE((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
 280         hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
 281         lastlen[dir][lastconn] = length - (hlen << 2);
 282         ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
 283         return 0;
 284 trunc:
 285         return -1;
 286 }